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Strawberry and cranberry response to growth regulators and fertilizers McArthur, David Albert James 1987

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STRAWBERRY AND CRANBERRY RESPONSE TO GROWTH REGULATORS AND FERTIL IZERS by DAVID ALBERT JAMES tic ARTHUR B . S c . ( A g r . ) , The U n i v e r s i t y oi B r i t i s h C o l u m b i a , 1983 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES (Depar tment of P l a n t S c i e n c e ) We a c c e p t t h i s t h e s i s as con- forming to t he r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1987 ©Dav id A l b e r t James M c A r t h u r , 1987 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of Plant Science The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 A p r i l , 1987 Date DE-fin/ft-n i i ABSTRACT The growth tnd y i t l d response of strawberry (Frtgtrit X ananasia Duch.) and cranbarry (Kaccj'ni'ua ncrocarpon A i t . ) to var ious growth i n h i b i t o r s , but e s p e c i a l l y to paclobutrazol (PP333), and f e r t i l i z e r s were inves t iga ted in glasshouse and f i e l d s t u d i e s . PP333 decreased vegetat ive growth in a rate-dependent manner in both strawberry and cranberry . PP333 delayed f r u i t r ipen ing in strawberry and decreased f r u i t set and frui t s i z e in cranberry . PP333 decreased po l len g e m i n a t i o n of strawberry. So i l res idues of PP333 were b i o l o g i c a l l y ac t ive when Measured 11 weeks after a p p l i c a t i o n in the strawberry study and when Measured af ter 50 weeks in a cranberry study. In a f i e l d study with cranberry , PP333 caused a decrease in vegetat ive growth and an increase in f lowering in the next season after treatment. Two-dimensional p a r t i t i o n i n g was used to account for yield v a r i a t i o n from treatment e f f e c t s on adjusted yield v a r i a t e s . The t russ number was the most important cont r ibutor to yield v a r i a t i o n in the strawberry, but was not a f fec ted by treatments. PP333 made a substant ia l cont r ibu t ion to yield v a r i a t i o n in strawberry through i t s e f fec t on frui t development and r i p e n i n g . In the cranberry , f ru i t set was the major contr ibutor to yield v a r i a t i o n and PP333 inf luenced yield s u b s t a n t i a l l y through i t s e f fec t on f r u i t se t . > In glasshouse studies,PP333 decreased shoot e longat ion in cranberry within 3 weeks of a p p l i c a t i o n , and increased the number of branches on primary shoots. Buds were formed within 7 weeks of treatment and some of the buds contained f lowers . Shoot growth was greater with a high rate of NPK f e r t i l i z e r than with the low f e r t i l i z e r rate and was greater in peaty s o i l than in sandy s o i l . While bud set was not modified by s o i l type or i i i f e r t i l i z e r r a t e , high NPK f e r t i l i z e r decreased f l o r a l i n d u c t i o n . Some e f f e c t s of PP333 treatment were decreased by g i b b e r e l l i c a c i d , but genera l ly these e f f e c t s Here not reversed. In a f i e l d study with the cranberry, PP333 increased flower bud set for f lowering and non-f lowering upr ights but s l i g h t l y decreased f l o r a l induct ion for non-f lowering upr igh ts . i v TABLE OF CONTENTS Paoe ABSTRACT i i LIST OF TABLES vi LIST OF FIGURES xi LIST OF SYMBOLS AND ABBREVIATIONS x i i ACKNOWLEDGEMENTS xv CHAPTER 1 - GENERAL INTRODUCTION 1 CHAPTER 2 - LITERATURE REVIEW 6 A. Growth habit b B. Runnering and genet ics • 8 C. Runnering and plant growth regula tors 8 D. Growth regula tors and mineral n u t r i t i o n 9 E. Growth and y i e l d r e l a t i o n s . . . . 10 CHAPTER 3 - EFFECT OF FERTILIZER, PACLOBUTRAZOL AND CHLORMEQUAT DN STRAWBERRY 13 Introduct i on 13 Mater ia ls and Methods 14 A. Strawberry growth response 14 B. Pol len germinat ion. 15 C. Bioassay for PP333 s o i l residues 16 Results and Discussion 17 A. Strawberry growth response 17 B. Pol len germination 2B C. Bioassay for PP333 s o i l residues 28 CHAPTER 4 - STRAWBERRY YIELD RESPONSE TO FERTILIZER, PACLOBUTRAZOL AND CHLORMEQUAT 30 In t roduct ion . . 30 Mater ia ls and Methods • 31 A. Strawberry * 31 B. S t a t i s t i c a l methods 32 Results and Discussion 32 A. Number of crowns •• 35 B. Leaf area 35 C. Number of t russes 38 D. Number of f lowers 38 E. Number of f r u i t s 41 F. Number of runner crowns 41 G. Number of r ipe f r u i t s 43 H. Number of achenes per f r u i t 43 I. Y ie ld response 45 V Page CHAPTER 5 - CRANBERRY RESPONSE TO GROWTH REGULATORS, FERTILIZER AND SOIL TYPE 48 Introduct ion • 48 Mater ia ls and Methods 49 A. Experiment 1. 1984 49 B. Experiment 2. 1984 50 (i) Bioassay for PP333 s o i l residues 51 C. Experiment 3. 1985 51 Results and Discussion 52 A. Experiment 1. 1984 52 B. Experiment 2. 1984 59 (i) Bioassay for PP333 s o i l residues 64 C. Experiment 3. 1985 66 CHAPTER 6 - CRANBERRY YIELD RESPONSE TO NITROGEN AND PACLOBUTRAZOL 76 I ntroduct i on 76 Mater ia ls and Methods 78 A. F i e l d experiments 78 B. S t a t i s t i c a l methods 79 Results and Discussion 80 A. 19B4 - Indiv idual f lowering uprights 80 B. 1985 - Indiv idual shoots 84 C. Unadjusted y i e l d components 86 D. Adjusted y i e l d components. . . 90 E. E f fec t of shoot type on bud s e t . . . . 94 F. Runner growth 100 CHAPTER 7 - GENERAL DISCUSSION 102 A. E f f e c t s of i n h i b i t o r s of GA-biosynthesis on vegetat ive growth and y i e l d . . . . . . . . . . . . 102 B. E f f e c t s of f e r t i l i z e r rate on vegetat ive growth and y i e l d . . . . . . 114 C. Y ie ld components • 123 D E f f e c t s of treatments on y i e l d components 124 E. Interact ions between PP333 and growth regulator treatments '125 F. Potent ia l use of PP333 in strawberry and cranberry • • 126 CHAPTER 8 - SUMMARY 129 CHAPTER 9 - REFERENCES 131 vi LIST DF TABLES CHAPTER 3 Paoe Table I. E f fec t of f e r t i l i z e r on number of runners in 'Totem' and 'Shuksan' strawberry 18 Table II. E f fec t of PP333 and CCC on number of runners in 'Totem' and 'Shuksan' strawberry 19 Table III. ANOVA (percentage of to ta l sums of squares) of e f f ec t of f e r t i l i z e r and growth regula tors on runner number in 'Totem' and 'Shuksan' strawberry 20 Table IV. E f fec t of f e r t i l i z e r , PP333 and CCC on to ta l leaf area in 'Totem' and 'Shuksan' strawberry. 22 Table V. E f fec t of PP333 and CCC on canopy t r a i t s and leaf senescence in 'Totem' and 'Shuksan' strawberry 23 Table VI. ANOVA (percentage of to ta l sums of squares) of e f fec t of f e r t i l i z e r , PP333 and CCC on canopy t r a i t s and leaf senescence of 'Totem' and 'Shuksan' strawberry 24 Table VII. E f fec t of PP333 and CCC on y i e l d , a t t r i b u t e s of y i e l d and harvest index of 'Totem' and 'Shuksan' strawberry 26 Table VIII . ANOVA (percentage of to ta l sums of squares) of e f fec t of f e r t i l i z e r , PP333 and CCC on y i e l d , a t t r i b u t e s of y i e l d and harvest index of 'Totem' and 'Shukan' strawberry 27 Table IX. So i l residue of PP333 (mg l" 1) 11 weeks af ter f o l i a r a p p l i c a t i o n to strawberry p lants with B. napus 'Westar' as a bioassay plant 29 CHAPTER 4 Table I. Sums of squares for e f f e c t s of f e r t i l i z e r , PP333 and CCC on vegetat ive and y i e l d var ia tes of s t r a w b e r r y . . . 33 Table II. Y ie ld v a r i a t i o n in glasshouse 'Totem' and 'Shuksan' strawberry p lants expressed as incremental cont r ibu t ions of successive adjusted orthogonal var ia tes to R z . Treatment e f f e c t s Dn var ia tes were p a r t i t i o n e d by ANOVA 34 v i i Table III. Table IV. Table V. Table VI. Table VII. CHAPTER 5 Table I. Table II. Table III. Table IV. Table V. Table VI. Table VII. F»ge E f fec t of f e r t i l i z e r rate on unadjusted and adjusted orthogonal var ia tes of strawberry. 36 E f fec t of PP333 and CCC on unadjusted and adjusted orthogonal var ia tes of strawberry 37 E f fec t of PP333 and CCC on unadjusted and adjusted orthogonal var ia tes of s t r a w b e r r y . . . 39 Cu l t i va r d i f f e rences in unadjusted and adjusted orthogonal var ia tes of s t r a w b e r r y . . . 40 E f fec t of PP333 and CCC on unadjusted and adjusted orthogonal var ia tes of s t r a w b e r r y . . . 44 Vegetat ive a t t r i b u t e s of rooted runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry in Experiment 1 53 Rate of primary shoot e longat ion and number of buds set per plant for rooted runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry treated with SADH and PP333 in Experiment 1. 55 E f f e c t of SADH and PP333 on vegetat ive a t t r i b u t e s of rooted runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry in Experiment 1 56 E f fec t of SADH and PP333 on shoot a t t r i b u t e s and bud set of rooted runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry in Ex per i ment 1 . . . . 57 E f fec t of f e r t i l i z e r rate and s o i l type on shoot a t t r i b u t e s and flower bud set of rooted runner cut t ings of ' M c F a r l i n ' ' and 'Ben Lear ' cranberry in Experiment 2 60 E f fec t of PP333 and f e r t i l i z e r rate or s o i l - t y p e on shoot a t t r i b u t e s and flower bud set of rooted runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry in Experiment 2 62 E f fec t of PP333 on shoot a t t r i b u t e s and bud set of rooted runner cu t t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry in Experiment 2 63 Table VIII . Table IX. Table X. Table XI. Table XII. Table XIII. Table XIV. Table XV. CHAPTER 6 Table I. Table II. Table III. Table IV. v i i i Page E f fec t of GA 3 and PP333 on germination and seedl ing length of B. napus 'Westar' af ter 48-hr incubat ion 65 B. napus 'Westar ' , bioassay of s o i l in cranberry experiment 2, 50 weeks af ter treatment with PP333 67 Shoot a t t r i b u t e s of rooted uprights and runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry in Experiment 3 68 Rate of primary shoot e longat ion for rooted unr ights and cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry treated with PP333 and GA 3 in Experiment 3 69 Shoot a t t r i b u t e s and bud set of rooted upr ights and runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry treated with PP333 and GA 3 in Experiment 3 70 Rate of primary shoot e longat ion for rooted upr ights and cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry t reated with PP333 and AC 94,377 in Experiment 3 71 Shoot a t t r i b u t e s and bud set of rooted uprights and runner cu t t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry treated with PP333 and AC 94,377 in Experiment 3 . . . . . . . 72 Shoot a t t r i b u t e s and bud set of rooted upr ights and runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry t reated with PP333 and NAA in Experiment 3 73 Shoot a t t r i b u t e s and bud set in 1984 f lower-ing upr ights of ' M c F a r l i n ' and 'Bergman' > cranberry t reated with ni trogen and P P 3 3 3 . . . ; » 81 Flowering and f r u i t i n g a t t r i b u t e s in 19B4 for f lowering upr ights of ' M c F a r l i n ' and 'Bergman' cranberry t reated with ni trogen and PP333 B3 Rate of shoot e longat ion in 1985 for 'Bergman' cranberry 85 Shoot a t t r i b u t e s and bud set in 1985 for 'Bergman' cranberry bog 87 ix Page Table V. Flowering and f r u i t i n g a t t r i b u t e s in 1985 for 'Bergman' cranberry 88 Table VI. Geometric means of y i e l d components for ' M c F a r l i n ' and 'Bergman' cranberry 89 Table VII. E f fec t of PP333 and nitrogen on geometric means of y i e l d components ' M c F a r l i n ' and 'Bergman' c r a n b e r r y . . . . . 91 Table VII I . Y ie ld v a r i a t i o n in ' M c F a r l i n ' and 'Bergman' cranberry expressed as incremental c o n t r i b -ut ions to R 2 with treatment e f f e c t s pa r t i t ioned by ANOVA 92 Table IX. Means of adjusted y i e l d components of ' M c F a r l i n ' and 'Bergman' cranberry 93 Table X. E f fec t of PP333 and nitrogen on adjusted means of y i e l d components of ' M c F a r l i n ' and 'Ben Lear ' cranberry 95 Table XI. Number of runners and upr ights ( U i j ) per dm2 for ' M c F a r l i n ' and 'Bergman' cranberry in 1984 96 Table XII. Buds per shoot for runners and upr ights ( Uxj) in 1984 for ' M c F a r l i n ' and 'Bergman' cranberry t reated with nitrogen and PP333 97 . Table XIII. Flower buds per bud in 1984 for ' M c F a r l i n ' and 'Bergman' cranberry treated with nitrogen and PP333 98 Table XIV. Runner growth and upright production in 1984 for ' M c F a r l i n ' and 'Bergman' cranberry treated with ni trogen and PP333 101 APPENDIX Table A . I . Chapter 3. The e f fec t of f e r t i l i z e r on growth-of 'Totem' and 'Shuksan' strawberry * 142 Table A . I I . Chapter 3. The e f fec t of PP333 on growth of 'Totem' and 'Shuksan' strawberry. 143 Table A. I I I . Chapter 6. Shoot a t t r i b u t e s and bud set of rooted upr ights and runner cut t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry treated with with PP333 and ABA in experiment 3 144 X Page Table A. IV. Chapter 5. The e f fec t of PP333 on shoot growth of ' M c F a r l i n ' and 'Ben Lear ' cranberry 145 Table A.V. Chapter 6. The e f fec t of PP333 and f e r t i l i z e r on ehoot growth of ' M c F a r l i n ' and 'Ben Lear ' cranberry 146 xi LIST OF FIGURES CHAPTER 7 Figures Page 1.1. The e f fec t of PP333 on whole plant dry weight of strawberry 103 1.2. The e f fec t of PP333 on runnering in strawberry 103 1.3. The e f fec t of PP333 on crown number of strawberry 105 1.4. The e f fec t of PP333 on y i e l d of s t r a w b e r r y . . . 105 2 .1 . The e f fec t of PP333 on whole plant dry weight of cranberry 107 2.2. The e f fec t of PP333 on shoot number of cranberry 107 2.3. The e f fec t of PP333 on y i e l d of c r a n b e r r y . . . . 110 3 .1 . The e f fec t of PP333 and NPK on whole plant dry weight of strawberry 117 3.2. The e f fec t of PP333 and f e r t i l i z e r on runnering on runnering in strawberry 117 3.3. The e f fec t of PP333 and f e r t i l i z e r on crown number of strawberry 119 3.4. The e f fec t of PP333 and f e r t i l i z e r on y i e l d of strawberry 119 4 .1 . The e f fec t of PP333 and f e r t i l i z e r on cranberry shoot dry weight 120 4.2. The e f fec t of PP333 and f e r t i l i z e r on shoot number of cranberry 120 4.3. The e f fec t of PP333 and f e r t i l i z e r on y i e l d of c r a n b e r r y . . . * 122 LIST OF SYMBOLS AND ABBREVIATIONS xi i ABA - a b s c i s i c acid AC 94377 - l - (3 -chlorophthal imido)-cyclohexanecarboxamide a . i . - ac t i ve ingredient AMO-1618 - 2-i sopropyl -4-d imethyl ami no-5-roethylphenyl-1-pi peri dene carboxylate methyl ch lo r ide ANOVA - ana lys is of variance B - number of f r u i t s per plant or upright Bg - 'Bergman' BL - 'Ben Lear ' C - c u l t i v a r Cr - number of crowns per plant D - dev ia t ion DA - number of developed achenes per f r u i t F - number of f lowers per plant or upr ight ; in the ANOVA t a b l e , F = f e r t i l i z e r 6A 3 - g i b b e r e l l i c acid 3 G A 1 9 - g i b b e r e l l i c acid 19 GA - g i b b e r e l l i n s H.I. - harvest index = r a t i o of dry weights of the f r u i t and whole plant IAA - l W - i n d o l e - 3 - a c e t i c acid L - l inear trend LA - leaf area per plant (ei ther with or without leaves of runners) log - logarithm Lp - leaf number i n i t i a t e d by parent plant crowns x i i i Lr - to ta l leaf number on runner p lants Ls - number of senescent leaves per plant McF - ' M c F a r l i n , NAA - 1-napthal eneacetamide NS - not s i g n i f i c a n t at f < 0.05 PL - p e t i o l e length (cm) PP333 - paclobutrazol PPFD - photosynthet ic photon f lux density Q - quadrat ic trend RB - number of r ipe f r u i t s per plant RCr - runner crown number per plant Res - res idua l v a r i a t i o n from TDP S - number of seeds per f r u i t for the cranberry; in the strawberry S = 'Shuksan' SADH - damino2ide SYCA - sequent ia l y i e l d component ana lys is T - number of t russes per plant in Chapter 4; in Chapter 3, T = 'Totem' TDP - Two-dimensional p a r t i t i o n i n g U - to ta l number of upr ights per dm2 U* - number of f lowering upr ights in 1984 per dm2 LU-f - number of upr ights per dm2 that flowered in both 1983 and 1984 U*v - number of upr ights per dm2 that flowered in 1984 but not 1983 Uv - number of non-f lowering uprights per dm2 in 1984 Uv-f - number of upr ights per dm2 that flowered in 1983 but not 1984 xiv Uw - number of upr ights per dm2 that did not flower in 1983 or 1984 W.P. - wettable powder X 2 - adjusted leaf area per plant without runner leaf area X 3 - adjusted number of t russes per plant X* - adjutted number of f lowar i per plant X s - adjusted number of f r u i t s per plant X 6 - adjusted number of runner crowns per plant X 7 - adjusted number of r ipe f r u i t per plant X 8 - adjusted number of developed achenes per f r u i t XX - v a r i a t i o n due to cross-products Y - to ta l r ipe f r u i t f resh weight. ACKNOWLEDGEMENTS I extend s incere thank6 to Dr. 6eorge W. Eaton for the many oppor tun i t ies to learn and the encouragement he has provided me during the las t four years . The f i n a n a c i a l support I received from Dr. Eaton is g r a t e f u l l y acknowledged. I thank Dr. Peter A. J o l l i f f e for h is he lp fu l suggestions and const ruc t ive c r i t i c i s m . I thank my other committee members, Dr. Iain E .P . -Tay lor , Dr. C. Norton and Dr. V. C. Runeckles for the i r he lpfu l suggest ions. Thanks are extended to Heinz Knoedler of Be l l Farms, and to Bruce May for the i r cooperation and the cranberry mater ia l . I am very grate fu l to C h r i s t i n e Seaman for her pa t ience , help and understanding during the more d i f f i c u l t times of th is t h e s i s . The research was supported by NSERC 6rants awarded to Dr. G.W. Eaton. CHAPTER 1. GENERAL INTRODUCTION 1 TNO important components for the management of many f r u i t crops to ensure high y i e l d s are the establishment of v igorous , ear ly f r u i t i n g plants and maximizing p lant ing dens i ty . Of ten , f e r t i l i z e r s , e s p e c i a l l y N, P and K, are recommended to promote plant growth so that the plant f i l l s i t s a l loca ted space q u i c k l y , to form a high number of potent ia l y i e l d bearing s t r u c t u r e s , and to replace the mineral nu t r ien ts los t through f r u i t production (Province of B r i t i s h Columbia Min is t ry of A g r i c u l t u r e and F i s h e r i e s , 1987a; 1987b). However, i t i s a common observat ion that between ind iv idua l - p l a n t s , c u l t i v a r s , s p e c i e s , loca t ions or years that p lants are qui te va r iab le in the i r response to f e r t i l i z e r s (Shoemaker, 1978j Teskey and Shoemaker, 1978). Of ten, i t i s d i f f i c u l t to prevent p lants from becoming too vegeta t ive , and as a r e s u l t , f r u i t q u a l i t y and quanti ty can be decreased, while the amount of pruning required can be increased . The June-bearing strawberry and the cranberry are two examples of important f r u i t crops in B r i t i s h Columbia. P lant ings of strawberry and cranberry in B .C. each had to ta l farm gate revenues of about $ 9 m i l l i o n per year between 1981 and 1984 (Province of B r i t i s h Columbia Min is t ry of A g r i c u l t u r e and F i s h e r i e s , 1986). While d i f f e r e n t in appearance and growth h a b i t , both strawberry, a herbaceous p e r e n n i a l , and cranberry , a woody p e r e n n i a l , are responsive to mineral supplements, e s p e c i a l l y n i t r o g e n , and tend to produce undesirable l a te or excessive runner growth when f e r t i l i z e d (Cannell et a l . , 19611 Tor io and Eck, 1969; B la t t and Crouse, 1970). 2 In both strawberry and c ranb i r ry c u l t u r a l systems, runner removal i i c o s t l y and d i f f i c u l t . In strawberry, a c u l t i v a t o r equipped with spec ia l d isks can be used between rows to t r i e runners, but runner reaoval within rows must be done by hand. In high densi ty p lant ings of strawberry, an add i t iona l problem of runner-pruning can be an o v e r - s t i e u l a t i o n of crown branching and a decrease in f r u i t f resh weight (Popenoe and Swartz, 1985; Swartz et a l . , 1985). In cranberry , a dry harvest mechanical p icker equipped with spec ia l blades i s used to pick up and tr im runners on the sur face of the bog, but t h i s method can damage upr igh ts . Some hand raking and pruning genera l ly are requ i red . An a l t e r n a t i v e method to pruning for the contro l of excessive vegetat ive growth would be of commercial b e n e f i t . Plant growth retardants such as chlormequat [ 2 - c h l o r o - H , N , H -trimethylethanammonium c h l o r i d e , (CCC)] and daminozide tbutanedioic acid mono(2,2-dimethylhydrazide) , (SADH)] decrease vegetat ive growth by i n h i b i t i n g g i b b e r e l l i n <6A) b iosynthes is (Dicks, 1980). In a d d i t i o n , these chemicals sometimes increase flower bud production of woody plants and are p o s s i b l e a l t e r n a t i v e s to pruning for contro l of vegetat ive growth in t ree f u i t s (Batjer et a l . , 1964; Hodlibowska, 1965; Wi l l i ams, 1972) and in ornamentals (Stuar t , 1961; Cathey, 1975 ). CCC i s widely used in Europe to contro l lodging in cerea ls grown with high ni trogen l e v e l s in in tens ive cropping systems (Lawrence 1984). Some studies suggest that these growth retardants may be useful a lso in strawberry or cranberry product ion . For example, in strawberry, f o l i a r sprays of CCC decreased runnering and increased the number of l a t e r a l crowns (Buttr idge et a l . , 1966). SADH appl ied at f u l l bloom at 2500 mg l _ x decreased winter in ju ry of cranberry (Doughty and Sheer, 1969) and at 1500 mg l _ x increased flower bud set for cranberry without 3 a f f e c t i n g y i e l d (Lenhardt and Eaton, 1976). Studies with both woody and herbaceous plants suggest that some of the observed e f f e c t s of growth i n h i b i t o r s on plants may not be a consequence of the i n h i b i t i o n of 6A-b iosynthes is on ly , but a lso Bight be the r e s u l t of induced changes in the l e v e l s of other endogenous plant growth regu la tors (Skene, 1968; F le tcher and Arno ld , 1986). Paclobutrazol r / -C <4-chl orophenyl) methyl !)-«*- (1,1-dimethyl e t h y l ) - 1 H -1 , 2 , 4 - t r i a z o l e - l - e t h a n o l , (PP333)3 i s a r e l a t i v e l y new growth retardant that i n h i b i t s BA-b iosynthes is (Da lz ie l and Lawrence, 1985; Hedden and Graebe, 1985). PP333 has been shown to decrease vegetat ive growth of ornamentals (Goulston and Shear ing, 1985), deciduous f r u i t t rees (Shearing et a l . , 19B6), orange trees (Swie t l i k , 1986) and berry crops (Wample et a l . , 1983; Haage, 1986; Stang and Weis, 1984). PP333 increased flower bud set in apple (Tukey, 1981) and increased the f i r s t flower f l u s h for orange (Iwahori and Tominaga, 1986). PP333 was e f f e c t i v e at lower concentrat ions than CCC and SADH, and i t s e f f e c t s are more pers is ten t (Quinlan, 1981; Copas and Wi l l i ams, 1983; Atkinson and C r i s p , 1982). PP333 has potent ia l as an a l t e r n a t i v e method to pruning in strawberry (Stang and Weis, 1984) and cranberry . The primary pupose of t h i s thes is was to inves t iga te the p o s s i b i l i t y that excessive runnering promoted by high NPK f e r t i l i z e r l e v e l s in e i ther the strawberry or the cranberry could be decreased by PP333 without causing detr imental e f f e c t s to general plant growth and y i e l d . ' It was a lso hoped that the response to f e r t i l i z e r could be s h i f t e d from vegetat ive to reproduct ive aspects of plant growth. The use of both strawberry and cranberry p lants in t h i s t h e s i s o f f e r s the advantages of having two d iverse plant types that are important in f r u i t production in B . C . ; the i r general growing requirements are well known; the p lants are 4 s n a i l and e a s i l y managed under glasshouse c o n d i t i o n s ! and, although the p lants are from two d i f f e r e n t f a a i l i e s , they can be considered as examples of p lants that respond to NPK f e r t i l i z e r by producing an undesirable amount of vegetat ive growth. A r e l a t i v e l y new method for i n v e s t i g a t i n g reasons for y i e l d v a r i a t i o n , two-dimensional p a r t i t i o n (TDP), was used to c l a r i f y plant growth and y i e l d r e l a t i o n s (Eaton et a l . , 1986). TDP combines the processes of sequent ia l y i e l d component a n a l y s i s (SVGA) and ana lys is of var iance (ANOVA) in a convenient form that allows i d e n t i f i c a t i o n of important cont r ibu tors to y i e l d v a r i a t i o n . TDP a lso provides an assessment of how treatments a f fec t y i e l d through adjusted y i e l d v a r i a b l e s . S p e c i f i c ob jec t ives of t h i s study were as fo l lows: 1) To determine a dose-response r e l a t i o n s h i p for PP333 on plant dry weight and f r u i t f resh weight in strawberry or cranberry . 2) To compare the e f f e c t s PP333 with CCC on vegetat ive growth of strawberry, or PP333 with SADH on vegetat ive growth of cranberry . 3) To determine the e f fec t of var ied f e r t i l i z e r rate on growth and y i e l d of the strawberry or the cranberry and to determine i f the e f f e c t s of PP333 modified those of the f e r t i l i z e r . 4) To determine the cont r ibu t ion of vegetat ive and y i e l d va r iab les to y i e l d v a r i a t i o n , and to assess the i n d i r e c t e f f ec t of treatment on y i e l d through adjusted y i e l d components. 5 5) To determine i f the e f f e c t s of PP333 on cranberry can be modified by other exogenously-appl ied growth r e g u l a t o r s , s p e c i f i c a l l y : a. 6A S [ < i * , 2 y M * * i 4 t y « 1 0 / 8 > - 2 , 4 a , 7 - t r i h y d r o x y - l - m e t h y l - B -methy leneg ibb -3 -ene - l , 10 -d ica rboxy l i c ac id 1 ,4a- lactone)3j b. AC 94,377 (1 - (3 -ch lorophtha l imi do)-eye 1ohexanecarboxamide), a compound that has e f f e c t s on plant growth s i m i l a r to 6A (Butt le and Bchre iner , 19B2)| c . NAA (1-naphthaleneacetamide)| d. or a b s c i s i c ac id (ABA) ( [S -<Z , f ) J -E5 - (1 -hydroxy -2 ,6 ,6 -t r i me thy l -4 -oxo -2 -cyc lohexen - l - y l ) - 3 -methy l -2 ,4 -pen tad ieno ic a c i d ) . This information might be useful i f reversa l of some e f fec t of PP333 were required under f i e l d c o n d i t i o n s . 6) As the r e s u l t s of these studies may be considered in decid ing the p r a c t i c a l use of PP333 in commercial production of f r u i t c rops , the e f f e c t s of PP333 on other f a c t o r s that might in f luence y i e l d , such as po l len germination and the a c t i v i t y of PP333 s o i l r e s i d u e s , were i n v e s t i g a t e d . • > CHAPTER 2 LITERATURE REVIEW 6 This t h e s i s was wri t ten as a s e r i e s of journal papers (Chapters three to s i x ) , each with i t s own i n t r o d u c t i o n , methods, and r e s u l t s and d i s c u s s i o n s e c t i o n s . Much oi the l i t e r a t u r e pert inent to t h i s thes is has been introduced and discussed within each oi these four chapters , but , due to the space cons t ra in ts imposed by the journal format, a f u l l d iscuss ion of the l i t e r a t u r e was not p o s s i b l e . Therefore , l i t e r a t u r e not i n c l u d e d , or only b r i e f l y d iscussed in Chapters three to six i s introduced here for the purpose of provid ing background information on t h i s t h e s i s as a whole. A. Browth habit The June-bearing strawberry, Fragria X an art ass a Duch. , i s a hybrid of F. virginiana Duch. and F. chiloerisis (L.) Duch. Both of these parent p lants o r i g i n a t e in North America but the l a t t e r i s found a lso in South America. Both are qui te va r iab le in growth c h a r a c t e r i s t i c s and hab i ta t . F. virqiniaria i s found in meadows and F. chiloens is i s found sometimes in land but mostly on beaches and on mountain slopes (Scott and Lawrence, 1975). Their h y b r i d , the June-bearing strawberry i s a low perennial herb with very short stems c a l l e d crowns from which develop a shallow root system, leaves and i n f l o r e s c e n c e s . Elongate stems c a l l e d runners (stolons) develop from some of the a x i l l a r y buds of new leaves that develop in the spr ing and summer. Runner crowns genera l ly are produced at advent i t ious buds at every second node of these stems. Branch crowns can develop a lso from the leaf a x i l l a r y buds but do so more in the la te summer. Flower buds d i f f e r e n t i a t e from the crown growing point in the 7 f a l l and grow out the the fo l lowing s p r i n g . D e t a i l s of plant Morphology and development have been descr ibed (Darrow, 1966). The cranberry , Vacciniua aacr ocar pon A i t . i s a low woody plant nat ive to open bogs and swamps of eastern North America. Some commercial c u l t i v a r s , such as ' M c F a r l i n ' , are r e l a t i v e l y recent wi ld- type s e l e c t i o n s , although breeding programs have re leased some useful c u l t i v a r s , such as 'Bergman' ( B a l l e t t a , 1975). The plant has a shallow root system and produces slender runners (vines) that sprawl along the ground with l a t e r a l buds producing s h o r t , v e r t i c a l stems c a l l e d upr igh ts . The leaves are small and have a s c l e r o p h y l l o u s , xeromorphic nature. This i s suggested to be an adaptation for more e f f i c i e n t nutr ient (N,P) r e c y c l i n g , although i t a lso appears to improve the p l a n t ' s water use e f f i c i e n c y (Smal l , 1972| Smal l , 1973). vegetat ive or mixed (f lowering) buds form on upr ights and runners in the la te summer and grow out in the fo l lowing Hay. The f lowers open s e q u e n t i a l l y during June and Ju ly and about t h i s time the induct ion of next y e a r ' s f lowers occurs (Roberts and Struckmeyer, 1943; Eaton and Lenhardt, 1976; Eaton, 197S). F l o r a l induct ion i s thought to compete with current flower and f r u i t development for plant nut r ien ts and growth regu la tors and t h i s r e s u l t s in a tendency for upr ights to bear f lowers and f r u i t in a l te rnate years (Lenhardt and Eaton, 1976; Eaton, 1978). F r u i t develop at the base of the new shoots and are considered strong ' s i n k s ' due to the i r high leve l of r e s p i r a t i o n and to the high concentrat ions of growth regu la tors present in the developing seeds (Zeevart et a l . , 1979). 8 B. Runnering and genet ics The strawberry has been the focus of much breeding research to iaprove i t s a d a p t a b i l i t y to c u l t u r a l systems ( C h i l d e r s , 1983). In Fragaria vesca, the runnering character i s simply inher i t ed and dominant (Brown and Nareing, 1965). In the c u l t i v a t e d strawberry, the runnering t r a i t i s more complex, but non-runnering i s h e r i t a b l e (Corbett and Header, 1965). Breeding to a l t e r the runnering habit of strawberry to su i t s p e c i f i c plant t r a i n i n g systems i s s t i l l in progress. The cranberry has only recent ly been brought in to c u l t i v a t i o n and much of the success of the cranberry industry has been a r e s u l t of matching the c u l t u r a l condi t ions to meet the requirements of the p lant . As a r e s u l t , the cranberry i s often grown in renovated peat bogs. L i t t l e work has been publ ished on the cranberry runnering charac te r , although minimizing runner growth has been l i s t e d as a modern breeding ob jec t ive ( G a l l e t t a , 1975). C. Runnering and plant growth regu la tors Plant growth regu la tors were impl icated in contro l of runnering of strawberry when f o l i a r a p p l i c a t i o n of g i b b e r e l l i c ac id (6A 3) was found to promote formation and growth of runners (Thompson and 6 u t t r i d g e , 1959). Levels of G A - l i k e substances were higher in apices of runners than crowns ( P o r l i n g i s and Boynton, 1961), and increased in crowns af ter a period of c h i l l i n g , before shoot growth commenced (Avigdor i -Avidov et a l . , 1977). Increased leaf growth and g i b b e r e l l i c ac id (GAi«> concentrat ion were measured in strawberry p lants grown with an 11-hr l i g h t per iod i f an add i t iona l 3-hr night break was given with low leve l l i g h t (Uematsu and Katsura , 1983). 6A appl ied to recent ly l a i d down meristems promoted runner ing , while GA plus a cy tok in in were required to promote runnering 9 of i n h i b i t e d l a t e r a l meristems (Bratin and Kender, 19B5). Involvement for BA in cranberry runnering i s not c l e a r l y e s t a b l i s h e d , but GA- l i ke substances Mere involved in bud-shoot growth af ter terminat ion of dormancy (Eady and Eaton, 1972). GA 3 increased shoot e longat ion and decreased flower bud set of cranberry (Devlin and Demoranvi l le , 1967). S imi lar to 8A 3 t reatments, high nitrogen f e r t i l i z e r rates increased runner ing , upright length and decrease flower bud set (Eck, 1976). An e f fec t of ni t rogen on competit ion between runner and f r u i t growth for nu t r ien ts and growth regula tors has been suggested (Eck, 1976). These studies suggest the p o s s i b i l i t y f l o r a l induct ion can be i n h i b i t e d by an e f fec t of ni t rogen on growth regula tors that e i ther promote or i n h i b i t flower bud se t . D. 6rowth regula tors and mineral n u t r i t i o n Mineral n u t r i t i o n may be involved in or in f luence the a c t i v i t y of endogenous plant growth r e g u l a t o r s . High plant ni t rogen l e v e l s can induce shoot growth of prev ious ly i n h i b i t e d l a t e r a l buds, poss ib ly through an e f fec t on auxin a c t i v i t y (Mclntyre, 1968). F luc tua t ions in ni t rogen supply to potato can cause s to lons to a l te rnate between stolon growth (high N) and t u b e r i z a t i o n (low N). This e f fec t can be mimicked by a l te rnate a p p l i c a t i o n of GA which induces s to lon growth or a b s c i s i c acid which induces tuber growth (Krauss and Marschner, 1976). High nitrogen f e r t i l i z e r s fed to plant roots can increase s to lon growth for potato in a fashion s i m i l a r to exogenous GA (Battelmacher and Marschner, 1979), and can increase G A - l i k e substances in tomato (Rajagopal and Rao, 1974). High plant ni t rogen l e v e l s a lso increased cy tok in in l e v e l s in sunflower (Wagner and Michae l , 1971) and potato (Sattelmacher and Marschner, 1978). The source of ni t rogen appears important, for ammonium 10 i t • n i t rogen source i i l e t * e f f e c t i v e et increas ing cy tok in in l e v e l s than n i t r a t e (Salama and Hareing, 1978; Horgan and Mareing, 1980; Dar ra l l and Nareing, 1981). Both 6A and cy tok in ins can in f luence the i n h i b i t o r y e f f e c t of auxin in l a t e r a l bud growth ( P h i l l i p s , 1969| P h i l l i p s , 1971| Moolley and Hareing, 1972). These s tudies i n d i c a t e an i n t e r a c t i o n between Mineral n u t r i t i o n and plant growth substances in the contro l of bud dormancy and l a t e r a l shoot Morphology. E. Growth and y i e l d r e l a t i o n s In the strawberry, crown number and l ea f area per plant were p o s i t i v e l y cor re la ted to y i e l d in the spaced plant c u l t u r a l systems (Sproat et a l . , 1935; Bedard et a l . , 1971; Gooding et a l . , 1975; Guttr idge and Anderson, 1981). S i m i l a r l y , in matted-row c u l t u r a l systems, ea r ly runner crown format ion, crown densi ty and leaf area were important y i e l d components (Hancock et a l . , 1983). Current season's y i e l d per plant and f r u i t number were inverse ly cor re la ted to the number of runners produced, p o s s i b l y through a competi t ion for nut r ien ts between vegetat ive and reproduct ive growth (Bedard et a l . , 1971; Nahdan and N a i s t e r , 1984). The number of f lowers and t russes per plant were observed to be h ighly and p o s i t i v e l y cor re la ted with y i e l d (Abbott et a l . , 1970). In high density p l a n t i n g s , such as in the r ibbon row system, overst imula t ion of crown branching decreased y i e l d , poss ib ly by a negative e f f e c t from shading on f r u i t set (Swartz et a l . , 1985).' In both the spaced plant and matted row systems, ni t rogen and phosphorus f e r t i l i z e r s are important to ensure adequate crown and leaf formation (Abbott, 1968; Shoemaker, 1978). Adequate crown development i s e s s e n t i a l for good flower bud set in the f a l l and y i e l d in the fo l lowing season. An increase in the number of t russes per plant together with a 11 decrease in the number of f lowers per t russ benef i ts y i e l d as f r u i t s i z e i s genera l ly greatest for primary f lowers (Darrow, 1966). While N, P and K f e r t i l i z e r s are recommended for good plant development and cropping (Shoemaker, 1978), high N rates have been observed to decrease current season's y i e l d through a negative e f fec t on f r u i t set or f lowers per t russ (Way and White, 1968). This may have been through the over-s t imula t ion of vegetat ive growth, and thus crowding and leaf shading. The maximum fresh weight of f r u i t was found to depend upon the number of i n i t i a t e d achenes and the amount of receptac le development per achene (Abbott et a l . , 1970). However, p o l l i n a t i o n and f e r t i l i z a t i o n are required to r e a l i z e t h i s maximum s i z e and the f i n a l f r u i t s i z e i s genera l ly determined by the number of developed achenes (N i tsch , 1950). The growth r e g u l a t o r , IAA (1H- indo le -3 -ace t ic a c i d ) , produced mainly by the achenes, exerts primary contro l over f r u i t enlargement, although GA a lso appears to be required (N i tsch , 1950; Thompson, 1964; L i s et a l . , 1978; Archbold and Dennis, 1984). In the cranberry , upright densi ty and growth were cor re la ted with y i e l d and an optimum densi ty of between 21.5 and 32.3 per dm2 was suggested (Roberts and Struckmeyer, 1942). Competition for l i g h t and nut r ients by weeds i n f e s t i n g a cranberry f i e l d was observed to decrease upright d e n s i t y , proport ion of upr ights f lower ing , f lowers per upright and f r u i t set (Hicks et a l . , 1968). These r e s u l t s genera l ly were confirmed in another study, although f lowers per upright and f r u i t set were not decreased (Yas and Eaton, 1982). Using SYCA, upright d e n s i t y , proport ion of upr ights f lower ing , f lowers per upr igh t , f r u i t set and berry s i z e were shown to be important cont r ibu tors to y i e l d v a r i a t i o n , although some v a r i a b i l i t y between l o c a t i o n s , c u l t i v a r s and years sampled was noted (Eaton and Kyte, 1978; 12 Eaton and MacPheraon, 1978j 8hawa at a l . , 19811 Yas and Eaton, 1982). In SYCA, p o t t n t i a l y i e l d components form a log add i t i ve model. Each component in the model, in i t s assumed order of morphological development, i s added sequent ia l l y in to a mul t ip le regress ion and the increment in R 2 i s c a l c u l a t e d . This al lows component compensation and an estimate of environmental in f luences to be determined. Component compensation has been detected between f r u i t set and f lowers per upr ight ; upright densi ty and proport ion of upr ights f lowering (Shawa et a l . , 1981); upright densi ty and f r u i t se t ; and upright density and f r u i t s i z e (Eaton and Kyte, 197B). A general p o s i t i v e e f fec t of an unknown environmental fac tor on both f lowers per upright and proport ion of upr ights f lowering was detected a lso (Eaton and Kyte, 1978). 13 CHAPTER 3 EFFECT OF FERTILIZER, PACLOBUTRAZOL AND CHLORHEQUAT ON STRAWBERRY INTRODUCTION In new strawberry p l a n t i n g s , f e r t i l i z a t i o n i s necessary to e s t a b l i s h and maintain the plant canopy. High ni t rogen l e v e l s can overst imulate both leaf production and runner ing. Ear ly runner production i s des i rab le in matted-row c u l t u r a l systems but runner removal eventual ly may become necessary to prevent overcrowding and to promote formation of l a t e r a l crowns. Late-rooted runners are l ess product ive than those root ing ear ly and compete for ass imi la tes during flower i n d u c t i o n . Control over plant vigor and runner i n i t i a t i o n would be of commercial b e n e f i t . Runner formation in strawberry plants i s long-day dependent and i s enhanced by high N l e v e l s , warm temperatures and a long w i n t e r - c h i l l i n g period (Darrow, 1937; Durner et a l . , 1984). Numerous reports impl icate g i b b e r e l l i n s (6A) or GA- l i ke substances as promoters of runner i n i t i a t i o n and development (Thompson and Gut t r idge , 1959; P o r l i n g i s and Boynton, 1961; Av igdor i -Av idov et a l . , 1977; Uematsu and Katsura , 19B3). Several s tudies ind ica te i n t e r a c t i o n s between mineral nut r ients and plant growth substances in bud dormancy and l a t e r a l shoot morphology (Hc lntyre , 1968; Woolley and Wareing, 1972; Rajagopal and Rao, 1974). Chemical regu la t ion of plant vegetat ive growth has not been adopted in strawberry cu l tu re but appears to have p o t e n t i a l . Exogenous cy tok in ins promote l a t e r a l crown formation in some strawberry c u l t i v a r s (Braun and Render, 19B5). F o l i a r sprays with 4% CCC can increase the number of l a t e r a l crowns and y i e l d and decrease runner ing, p o s s i b l y through a decrease in the leve l of 6A (Guttr idge et a l . , 1966). PP333 and CCC i n h i b i t 6A b iosynthes is and may a l t e r the l e v e l s of other endogenous plant hormones such as cy tok in ins in grapevines (Skene, 196B) and ethylene in apple (Hang and S t e f f e n s , 1985) and may delay leaf senescence in tomato, bean and b r o c c o l i (Halevy et a l . , 1965) and soybean (Upadhyaya et a l . , 1985). The dose responses of strawberry to PP333 have been inves t iga ted (Stang and He is , 1984; Atkinson et a l . , 1985; Ramina et a l . , 1985; Braun and 6ar th , 1986). Low rates of PP333 decreased runnering and vegetat ive growth without reducing y i e l d , although a delay in r ipening was noted (Stang and He is , 1984; Ramina et a l . , 1985). C u l t i v a r d i f f e rences in dose response to PP333 have a lso been reported (Atkinson et a l . , 1985; Braun and Garth , 1986). This study compared PP333 with CCC for contro l of f e r t i l i z e r -st imulated vegetat ive growth of two June-bearing strawberry c u l t i v a r s . Two further s tudies were conducted to determine the e f fec t of PP333 on po l len germination and the a c t i v i t y of PP333 residues in the s o i l as these may be important f ac to rs in determining i t s commercial use fu lness . MATERIALS AND METHODS A. Strawberry growth response There were 32 treatments c o n s i s t i n g of the combinations of 2 c u l t i v a r s , 2 l e v e l s of f e r t i l i z e r and 8 growth retardant so lu t ions randomly arranged in each of 6 complete b l o c k s . 15 On 29 Feb. 1984, dormant crowns of 'Bhuktan' and 'Totem' Mire planted in a mix of s o i l , p e r l i t e and peat ( B i l i l v/v/v) in 19-cn pots which Mere randomized on a glasshouse bench with a temperature maintained at about 2S°C (day) / 20°C (n ight ) . On 5 Mar. 1984, B cool f luorescent lamps (100 W each) Mere placed in each block 27 cm above the crowns to give a d a i l y 12-hr photoperiod a l te red to 16 hr a f ter 3 weeks. The l i g h t s Mere ra ised B weeks l a t e r to avoid shading. Plants were f e r t i l i z e d biweekly for 16 week with 45 mg per a p p l i c a t i o n (Peter 's Pro fess iona l 20N-B.7P-16.6K with 0.05X Mg and Fe, Mn, Zn, Cu, B, Mo) per pot or 1B0 mg/pot. Growth retardants in a 0.1X Tween'20 so lu t ion were appl ied at the beginning of the nyctoperiod as shoot sprays to runoff (25 ml /p lant ) on 27 Mar. (prebloom) and again 2 week la te r ( f u l l bloom). The PP333 used was a 25X a . i . suspension (ICI Americas from Chipman Inc.) and was appl ied at concentrat ions of 0, 10, 46, 215 or 1000 mg l - 1 a . i . CCC was appl ied at 0, 215, or 1000 mg l _ l on ly , as previous reports had ind icated that such high rates would be required to decrease runnering of strawberry (Gut t r idge, 1966). F r u i t was harvested when r i p e . Plants and the i r runners were allowed to develop u n t i l 3 June 1984 when the senesced leaves were counted. B. Pol len germination Pol len was c o l l e c t e d from f ie ld -grown 'Totem' and 'Shuksan' p lants and stored in a des iccator at 4°C for several weeks. Pol len was then placed on s l i d e s coated with a 10% sucrose and 0.75X agar medium and randomized in 15 complete b l o c k s . S l i d e s were sprayed with PP333 at 0, 10, 46, 215 or 1000 mg l _ l a . i . in 0.1X Tween'20 and incubated for 2 hours at 21°C with cool white f luorescent l i g h t . Po l len germination 16 was determined for 100 gra ins on each e l i d e and analyzed with a n a l y s i s of var iance . C. Bioassay for PP333 s o i l residues After the f i n a l harvest , s o i l f roe the pots of 'Totem' f e r t i l i z e d with high NPK from each of the 6 blocks was a i r dr ied and s i f t e d through a 6 mm (1/4 in) screen for bioassay of PP333. S o i l samples of 125 g were t rans fe r red to 172-ml (6 oz) polystyrene foam cups. For a bioassay standard, s o i l from contro l pots had 6 ml of PP333 at 0, 10, 46, 215 or 1000 mg 1 _ 1 0.1X Tween'20 added to cups within the i r o r i g i n a l blocks and both standard and test cups were made up to 145 g with 0.1X Tween'20 s o l u t i o n . The next day seeds of Brassi'ca napus ' M e s t a r ' , 12 per cup, were sown 1.5 cm deep and the cups were made up to 165 g with d i s t i l l e d water and 15 mg of 20N-8.7P-16.6K with micronutr ients was added to each cup. The cups were placed in a growth chamber at 27°C on a 14-hr photoper iod. The cups were placed 30 cm below cool white f luorescent tubes and incandescent bulbE prov id ing a PPFD of 500y^mol s _ 1 m ~ 2 . The cup sample weight was made up tD 165 g with d i s t i l l e d water d a i l y and the seedl ings thinned to the most uniform 10 (Santelmann et a l . , 1971). Record was kept of d iurnal water loss over the 18th day per iod and at f i n a l harvest shoot measurements were taken. Shoot length and to ta l water evapotranspired over the IB day per iod were used to determine the e f f e c t s of known amounts of PP333 on evapotranspi ra t ion and shoot l eng th , and these r e s u l t s were used to estimate PP333 concentrat ions in the s o i l from strawberry p lants t reated with PP333. Mean s o i l pH was 6.7 for 16 randomly sampled cups at the end of the b ioassay. 17 In the presentat ion of r e s u l t s and the i r d iscuss ion in t h i s and each of the fo l lowing chapters , e f f e c t s of t reataents on the Measured var ia tes re fer to those that were s t a t i s t i c a l l y s i g n i f i c a n t with P < 0.05. RESULTS AND DISCUSSION A. Strawberry growth response Plants grown at the greater rate of f e r t i l i z a t i o n had increased root and shoot dry weight, number of leaves , l a t e r a l crowns (Appendix Table A.I) and runners in comparison with plants at the lower rate (Table I). Increases in runner production were only evident in the la te weeks of the experiment. Leaf senescence was decreased (P=5.7X) and f r u i t r ipen ing delayed with NPK at 180 mg/pot in comparison with 45 mg/pot. 'Shuksan' produced more runners in the period up to 19 Apr. Af ter 19 A p r . , 'Totem' produced more runners u n t i l 26 Hay when s i g n i f i c a n t c u l t i v a r d i f f e rences in runner numbers disappeared (Tables II and I I I ) . PP333 at 46, 215 or 1000 mg l - 1 was more e f f e c t i v e in decreasing runner number than CCC at 215 or 1000 mg l " 1 . 'Totem' was more responsive to PP333 than 'Shuksan' while the reverse was true for CCC. The ear ly runner production of 'Shuksan' and the shorter pers is tence of CCC, r e l a t i v e to PP333, in the s o i l poss ib ly expla in d i f f e rences in c u l t i v a r s e n s i t i v i t y to CCC (Jung, 1964; Kuhn, 1964). S i m i l a r l y , the la te r runner production of 'Totem' and the longer res idua l a c t i v i t y of PP333 could expla in the greater s e n s i t i v i t y of 'Totem' to PP333. Leaves of p lants t reated with PP333 appeared darker green than leaves of contro l p l a n t s . This e f fec t has been a t t r ibu ted to increased TABLE I E f f e c t of f e r t i l i z e r on number of runners in 'Totem' and 'Bhuksan' strawberry. NPK treatment 5-19 Apr. 20 Apr . -26 Hay Total Low 1.74 1.98 3.72 High 1.79 2.60 4.40 S i g n i f i c a n c e NS ### et* NS • not s i g n i f i c a n t , or # P < 0.05, ** P < 0 .01, #«« P < 0.001. 19 TABLE II E f f e c t of PP333 and CCC on number of r u n n t r i in 'Totem' and 'Bhuksan' s t rawber ry 1 . Treatment 5- 19 Apr. 20 Apr .-26 Hay Total Totem Shuksan Totem Bhuksan Totem Bhuksan PP333 (mg l" 1) 0 2.7 3.3 4.0 1.8 6.7 5.1 10 2.0 2.3 4.3 2.7 6.3 5.0 46 1.1 2.3 1.4 1.6 2.5 3.8 215 0.2 1.2 0.1 0.9 0.3 2.1 1000 0.0 0.1 0.0 0.2 0.0 0.3 CCC (mg l" 1 ) 0 2.4 2.5 3.6 3.3 6.0 5.8 215 2. 1 2.1 4.8 2.B 6.8 4.9 1000 1.3 2. 1 3.8 2.3 5.1 4.3 • F o l i a r sprays of 25 ml 2 week pr io r to and at f u l l bloom. See Table III for ANOVA. TABLE III ANOVA (percentage of to ta l sums of aquares) of e f f ec t of f e r t i l i z e r and growth regu la tors on runner number in 'To ten ' and 'Shuksan' strawberry Source df 5-19 Apr. 20 Apr . -26 Hay Total Block 5 2 1 0 C u l t i v a r (C) 1 4* * * 0 F e r t i l i z e r (F) 1 0 3* * * 2 * * * Control vs . PP333 1 IB*** 6*## 17### PP333 log l inea r 1 l©**# 22*** 33* * * PP333 log quadrat ic 1 0 2** 1«* PP333 dev ia t ion 1 0 0 0 Control vs . CCC 1 2* 0 1* 215 vs . 1000 CCC 1 1 1* 1**« PP333 vs . CCC 1 3** 19*** 19*** C X F e r t i l i z e r 1 0 0 0 C X Control vs . PP333 1 0 3«*« 2* * * C X PP333 log l inea r 1 0 I* 1* C X PP333 log quadrat ic 1 1 2** 2* * * C X PP333 dev ia t ion 1 0 0 0 C X Control vs . CCC 1 0 1* 1* C X 215 vs. 1000 CCC 1 1 0 0 C X PP333 vs . CCC 1 0 1 1«* F e r t i l i z e r X Retardant 7 2 2 1 C X F X Retardant 7 1 1 1 Error 155 49 31 17 Total (X) 191 100 100 100 Sum of squares 334 750 1236 NS « not s i g n i f i c a n t , or * P < 0.05, * * P < 0.01, * * * P < 0.001. 21 ch lo rophy l l content per uni t leaf area (Bankhla i t a l . , 1985). PP333 decreased root dry weight and t russ length of p lants (Appendix Table A . I I ) . PP333 at 215 or 1000 eg l ~ l resu l ted in shortened new leaf p e t i o l e s and produced very compact p lants with leaves c lus te red at t he i r centres (Stang and Weis, 1984). S imi la r e f f e c t s for CCC were not apparent, although there was some i n t e n s i f i e d leaf greening at 1000 mg ] - » . Both CCC and PP333 decreased to ta l leaf area by decreasing runner leaf number but PP333 was more e f f e c t i v e (Tables IV and VI) . PP333 decreased area per leaf but CCC did not (Appendix Table A . I I ) . The increment in to ta l leaf area promoted by NPK at 180 mg/pot r e l a t i v e to 45 mg/pot was almost l o s t at the greater ra tes of PP333. P lants t reated with 46 mg l " 1 of PP333 and the higher NPK rate s t i l l had considerable canopy development and a greater to ta l leaf area than plants treated only with the low NPK r a t e , despi te a decrease in runner number caused by PP333. This increase in to ta l leaf area apparently resu l ted from an increase in number of leaves i n i t i a t e d and in a decrease in leaf senescence for parent p lants due to both high NPK and PP333 (Tables V and VI) . The PP333 induced delay in senescence i s reminiscent of both responses to CCC (Halvey et a l . , 1965) and the well-known e f f e c t s of exogenous c y t o k i n i n s . Delayed leaf senescence may re la te to an increased a v a i l a b i l i t y of nut r ien ts and the i n h i b i t i o n of ' s i n k s ' , such as runners and f r u i t s , which compete for nu t r ien ts (Leopold and Kriedemann, 1975). PP333 decreases endogenous polyamine content , i n h i b i t s ethylene b i o s y n t h e s i s , delays a senescence- l inked r i s e in peroxidase a c t i v i t y (Upadhyaya et a l . , 1985j Wang and S t e f f e n s , 1985). CCC has been reported to delay senescence for tomato, bean, and TABLE IV E f fec t of f e r t i l i z e r , PP333 and CCC on to ta l leaf area in 'Totem' and 'Shuksan' s t rawberry 1 NPK 2 Treatment Low High PP333 <mg l" 1) 0 1582 2042 10 1545 1808 46 1272 1745 215 1034 1178 1000 721 801 CCC (mg I"1) 0 1579 2139 215 1610 1936 1000 1520 1954 'See Table VI for ANOVA. Leaf area in cm 2 . 2Low and high NPK were 45 mg and 180 mg per pot of 20N-8.7P-16.6K respect i ve ly . TABLE V E f f e c t of PP333 end CCC on canopy t r a i t s and leaf senescence in 'Totem' and 'Bhuksan' s t rawberry 1 LA 1 Lp Lr PL Ls Treatment T S T B T S T S T S PP333 (mg 1"M 0 1958 1666 15 18 15 24 11 10 3 4 10 1659 1694 16 20 13 21 9 10 2 2 46 144B 1569 17 20 8 17 7 B 1 3 215 976 1236 21 21 0 10 4 6 1 I 1000 631 B90 21 23 0 1 3 3 0 0 CCC (mg I"1) 0 1936 1781 15 19 17 25 10 10 2 3 215 1917 1628 16 IB 14 23 11 10 3 3 1000 1765 1709 16 22 10 17 10 10 3 4 'See Table VI for ANOVA. LA = leaf area per plant (cm 2 ) , Lp ° leaf number on parent p l a n t s , inc lud ing senescent l eaves , Lr B leaf number on runner p l a n t s , PL * p e t i o l e length (cm), Ls B number of senescent l eaves , T • Totem, S • Shuksan. TABLE VI ANOVA (percentage of to ta l I U I I of squares) of e f fec t of f e r t i l i z e r , PP333 and CCC on canopy t r a i t s and leaf senescence of 'Totem' and 'Bhuksan' strawberry Source df LA 1 Lp Lr PL Ls Block 5 2* 3 3«» 3««« 2 C u l t i v a r (C) 1 0 10##* 15*** 0 6 * * « F e r t i l i z e r (F) 1 13*** 5* * * 2 * * * 1* 1 Control vs . PP333 1 14*** 5* * * 14*** 19*** 13*** PP333 log l inea r 1 2B**« 6*** 21* * * 35*** 15*** PP333 log quadrat ic 1 1* O 0 0 0 PP333 dev ia t ion 1 0 1 0 0 0 Control vs . CCC 1 1* 0 1** 0 0 215 vs . 1000 CCC 1 0 2* 1*» 0 0 PP333 vs . CCC 1 IB*** 2* 12*** 25** * 17*** C X F e r t i l i z e r 1 0 0 0 0 0 C X Control vs . PP333 1 2 * * * 0 0 2* * * 0 C X PP333 log l inea r 1 1* 1 1 0 0 C X PP333 log quadrat ic 1 0 0 1* 0 2** C X PP333 dev ia t ion 1 0 0 0 0 0 C X Control vs . CCC 1 0 0 0 0 0 C X 215 vs . 1000 CCC 1 0 1 0 0 0 C X PP333 vs . CCC 1 2 * * * 1 0 1** 1 F X Control vs . PP333 1 1* 0 0 0 0 F X PP333 log l inea r 1 1* 0 0 0 0 F X PP333 log quadrat ic 1 0 0 0 0 0 F X PP333 dev ia t ion 1 1* 0 0 0 1 F X Control vs . CCC 1 0 0 0 0 0 F X 215 vs. 1000 CCC 1 0 0 0 0 0 F X PP333 vs. CCC 1 1* 0 0 0 0 C X F X Retardant 7 1 1 0 1 1 Error 155 15 60 27 13 39 Total (X) 191 100 100 100 100 100 Sum of squares (xl0~ 3 ) 43000 4. 791 23.04 1.B2 0.4B NS = not s i g n i f i c a n t , or * P < 0.05, * * P < 0.01, * * « P < 0. 001. 1 LA «= leaf area per plant (cm 2 ) , Lp = leaf number on parent p lants inc lud ing senescent l eaves , Lr • leaf number on runner p l a n t s , PL » p e t i o l e length (cm), Ls B number of senescent leaves . 25 b r o c c o l i (Halvey et a l . , 1965), but t h i s e f fec t was not observed during the present study at the ra tes used. Y ie ld per plant dec l ined with increas ing PP333 rates but , despi te a large decrease in y i e l d at the highest r a t e , Mas not s i g n i f i c a n t l y d i f f e r e n t f roe con t ro ls or p lants t reated with CCC (Tables VII and VI I I ) . A delay in r ipen ing caused by PP333 (Stang and Ne is , 1984) could account for our observat ion of a decrease in y i e l d . A decrease in r ipe f r u i t number Mas p a r t i a l l y of faet by an increase in f r u i t f resh weight compared to con t ro ls and plants t reated with CCC. Although contro l values were not included in a s t a t i s t i c a l test of s i g n i f i c a n c e in the trend ana lys is due to the use of log concent ra t ions , our observat ions suggest that the low concentrat ions of PP333 may have increased y i e l d . Others a lso have reported increases in f resh weight of f r u i t with PP333 (Stang and Weis, 1984; Ramina et a l . , 1985). CCC increased y i e l d for 'Shuksan' through an increase in f r u i t f resh weight, but decreased y i e l d s l i g h t l y for 'Totem' (Table VI I ) . F r u i t s from plants t reated with PP333 had more achenes per r ipe f r u i t r e l a t i v e to con t ro ls and plants t reated with CCC (Table VI I ) . Seed abort ion was not inves t iga ted in the present study but PP333 has been reported to decrease seed abort ion in ryegrass (Hampton and Hebblethwaite, 19B5). PP333 delayed r ipening of both c u l t i v a r s but more so in the case of 'Totem' f r u i t than 'Shuksan ' . Unripe f r u i t s from plants with PP333 often had large plump achenes and l i t t l e receptac le development. The harvest index (HI), the r a t i o of f r u i t dry weight to plant dry weight, was decreased by PP333 only at 1000 eg l " 1 (Table VI I ) . At low rates vegetat ive growth was more s e n s i t i v e to PP333 than was f r u i t 26 TABLE VII Effect of PP333 and CCC on y ie ld , attributes of yield and harvest index of 'Totem' and 'Shuksan' strawberry 1 Yield Ripe f ru i t No. achenet No. ripe No. unripe Harvest (g) fresh wt(g). per f rui t f ru i ts f ru i ts index Treatment (ag I"1) T S T S T S T S T S T S PP333 0 IB.7 22.6 2.7 3.7 12.1 23.5 6.5 5.B 1.6 0.3 7.0 6.B 10. 27.7 36.5 4.2 5.0 36.9 41.7 6.9 7.2 3.5 0.6 9.1 10.6 46 27.2 23.2 4.5 4.7 43.8 35.1 5.8 4.7 3.4 1.3 10.5 7.8 215 21.4 IB.8 4.7 5.5 46.4 53.2 5.0 3.4 4.8 i.B 12.1 B.8 1000 6.0 1.8 2.9 1.8 43.5 21.6 1.6 0.3 10.3 3.8 3.7 1.2 CCC 0 22.2 19.3 2.5 3.3 16.9 19.2 7.3 6.2 0.B 0.6 7.2 5.7 215 16.2 34.0 2.4 4.1 10.e 26.B 6.5 e.o 1.3 1.2 6.0 9.7 1000 19.0 30.7 2.4 4.3 13.0 29.1 7.3 6.4 1.2 1.3 7.2 8.4 •Bee Table VIII for ANOVA, T •> Totem, 5 « Shuksan. 27 TABLE VIII ANOVA (percentage of total sues of squares! of effect of f t r t l l i z t r , PP333 and CCC on y i e l d , attr ibutes of yield and harvest index of 'Totea' and 'Bhuksan' strawberry. Ripe No. f ru i t achenes No. No. Yield fresh per ripe unripe Harvest Bource df (g) wt (g) f ru i t f ru i ts f ru i ts index Block 5 6«» 1 2 10*»« 2 8*« Cultivar (C) 1 t 4*# 1 1 fit** 0 Fer t i l i ze r (F) 1 0 0 0 0 It 1 Control vs. PP333 1 0 2* 10»*» 2* 6*t* 0 PP333 log linear 1 17«»» 7»»» 0 17«»* 13*»» 10**« PP333 log quadratic 1 1 7*** 2* 0 3t# 6*t* PP333 deviation 1 0 2» 2« 0 0 3«« Control vs. CCC 1 1 0 0 0 0 1 215 vs. 1000 CCC 1 0 0 0 0 0 0 PP333 vs. CCC 1 1 4«» 13»** 8*t* 8*** 0 C X Fe r t i l i ze r 1 0 0 0 0 1 0 C X Control vs. PP333 1 0 1 1 0 1« 0 C X PP333 log linear 1 1 1 1 0 2* 1 C X PP333 log quadratic 1 0 0 0 0 1* 1 C X PP333 deviation 1 0 1 2« 0 0 0 C X Control vs. CCC 1 2* 1 0 0 0 I C X 215 vs. 1000 CCC 1 0 0 0 1 0 0 C X PP333 vs. CCC 1 t 2« 2* 0 5*** 1» F X Control vs. PP333 1 0 0 0 0 0 0 F X PP333 log linear 1 0 2* 2* 0 0 0 F X PP333 log quadratic 1 0 1 1« 0 0 0 F X PP333 deviation 1 1 0 0 1 1 1 F X Control vs. CCC 1 0 0 0 0 0 0 F X 215 vs. 1000 CCC 1 0 0 0 0 0 0 F X PP333 vs. CCC 1 0 0 0 0 0 0 C X F X Retardant 7 5 6 4 2 2 4 Error 155 61 5B 55 55 45 59 Total U) 191 100 100 100 100 100 100 Sum of squares 57478 692 93202 2652 2376 0.49 NS «= not s ign i f i can t , or » P < 0.05, ** P < 0.01, *«# P < 0. 001. 28 development. Neither the NPK e f fec t nor the PP333 X NPK e f f e c t s upon HI Mere s i g n i f i c a n t . B. Pol len oermination PP333 decreased germination of po l len in the present study ( P « 0 . 1 X ) . B i b b e r e l l l n s have been found in po l len and nay be involved in g e m i n a t i o n (Stanley and L i n s k i n s , 1974). The e f fec t of PP333 on po l len germinat ion, e s p e c i a l l y at 1000 mg l " 1 , may have contr ibuted to a delay in f r u i t development. C. Bioassay for PP333 s o i l residues At the end of the experiment, small amounts of PP333 remaining in the s o i l were detected by bioassay even though there Mas l i t t l e d i rec t s o i l a p p l i c a t i o n of the material (Table IX). Leaves of B. napus seedl ings exposed to PP333 M e r e darker green than those of seedl ings not exposed to PP333. Cotyledons on seedl ings exposed to PP333 Mere observed to be re ta ined longer than on other s e e d l i n g s , which suggested PP333 delayed senescence . While seedl ing emergence, mean seedl ing dry weight and leaf area a l l detected PP333 r e s i d u e s , only evapotranspi ra t i on and shoot length were reported as they were more s e n s i t i v e i n d i c a t o r s . A h a l f - l i f e estimate of 3 to 6 months (Pickard et a l . , 19B3) and s o i l a c t i v i t y of at l eas t 1 year have been reported (Copas and Wi l l i ams, 1983). The present f ind ings suggest that a small amount of PP333 remained ac t ive in the s o i l for at least 11 weeks, the per iod from the l a s t a p p l i c a t i o n of PP333 to the beginning of the bioassay in our experiment. TABLE IX S o i l residue of PP333 (eg l - 1 ) 11 weeks af ter f o l i a r a p p l i c a t i o n to strawberry p lants with B, napus 'Westar' i s a bioassay p lant . Estimated concentrat ions of PP333 (eg 1~M in s o i l using two d i f f e r e n t va r iab les PP333 (eg l ~ l > Shoot length Evapotranspi ra t ion 0 0.0 0.0 10 0.0 0.2 46 0.0 0.6 215 0.1 0.7 1000 2.7 5.4 CHAPTER 4 STRAWBERRY YIELD RESPONSE TO FERTILIZER, PACLOBUTRAZOL AND CHLORHEQUAT 30 INTRODUCTION Recent research on chemical contro l of excessive plant vigour ind ica tes paclobutrazol at r e l a t i v e l y low rates eay e f f e c t i v e l y suppress runner fo rea t ion of strawberry without detr imental e f f e c t s on overa l l plant growth and y i e l d (Stang and Weis, 1984; Atkinson et a l . , 1985; Ramina et a l . , 19B5; Braun and Garth , 1986). The dose-response to PP333 in strawberry eay depend on c u l t i v a r type (Atkinson et a l . , 1985; Braun and 6ar th , 1986). The r e l a t i o n s h i p between vegetat ive and reproduct ive var ia tes as a f fec ted by PP333 and aspects of plant c u l t u r e , but has not been thoroughly i n v e s t i g a t e d . High rates of f e r t i l i z a t i o n (NPK) are often used in strawberry p lant ings for rapid canopy establ ishment , but excessive runner formation may be promoted under these condi t ions (Cannell et a l . , 1961; B la t t and Crouse, 1970). Runner removal can be d i f f i c u l t and c o s t l y , e s p e c i a l l y with h igh-dens i ty uniform p lant ing systems. Plant N status has been cor re la ted with l e v e l s of endogenous g i b b e r e l l i n s (GA) (Rajagopal and Rao, 1974) and high 6A l e v e l s appear to favour runner formation in a x i l l a r y buds (Thompson and Gut t r idge , 1959; P o r l i n g i s and Boynton, 1961; Wool ley and Wareing, 1972). Thus, 6 A - i n h i b i t o r s such as PP333 may be a useful adjunct to high NPK for rapid and economical establishment of p l a n t i n g s . One problem of evaluat ing treatments i s the p o s s i b l e opposi te e f f e c t s on i n d i v i d u a l var ia tes of p lants that tend to cancel any benef i t to y i e l d . While ANOVA can be used to assess treatment e f f e c t s on plant 31 var ia tes i t does not show the i r d i r e c t con t r ibu t ion to y i e l d . Sequential y i e l d component a n a l y s i s (SYCA) measures the cont r ibu t ions of plant va r ia tes or y i e l d components to y i e l d v a r i a t i o n but does not provide an assessment of treatment e f f e c t s . Recently the two methods Mere combined to p a r t i t i o n adjusted orthogonal cont r ibu tors to y i e l d by l i n e a r regress ion ana lys is in one dimension and v a r i a t i o n among treatments and other fac to rs of the experimental design in a second dimension in a combined TDP (Eaton et a l . , 1986). Our study uses both ANOVA and TDP for determination of the e f f e c t s of PP333 and CCC on vegetat ive and f r u i t growth of strawberry p lants grown with a low and high rate of NPK. MATERIALS AND METHODS A. Strawberry Treatments consis ted of a l l 32 combinations of 2 c u l t i v a r s , 2 l e v e l s of f e r t i l i z e r and 8 treatment s o l u t i o n s , randomly arranged in each of 6 complete b locks . Experimental design and some r e s u l t s have been reported prev ious ly (McArthur and Eaton, 1987a or Chapter 3) . 'Shuksan' and 'Totem' dormant crowns were grown in a mix of s o i l , peat and p e r l i t e (8:1:1 v / v / v ) in a glasshouse at 25°C (day) / 20°C (night) with supplemental f luorescent l i g h t i n g (16-hr photoper iod) . Plants were f e r t i l i z e d f o r t n i g h t l y for 16 weeks with a low (45 mg/pot) or a high (180 mg/pot) rate of 20N-8.7P-16.6K with micronut r ien ts . Growth retardants in a 0.1X Tween'20 s o l u t i o n were appl ied as shoot sprays to runoff (25 ml /p lant ) on 27 March at prebloom and again two weeks la te r at f u l l - b l o o m . PP333 rates were 0, 10, 46, 215 or 1000 mg 1 _ 1 from a 25X a . i . suspension (ICI Americas v ia Chipman Inc.) 32 and CCC rataa were 0, 215, or 1000 ng l - 1 . F r u i t s ware harvested when uniformly red . Plants and the i r runners were allowed to develop u n t i l 3 June 1984 (95 days) . Data col 1 acted from each plant included C r , LA, T, F , 6, RCr, RB, DA, Y. B. S t a t i s t i c a l methods Treatment e f f e c t s were f i r s t examined using ANOVA on the unadjusted vegetat ive and reproduct ive plant va r ia tes (Table I). The v a r i a t e s , Cr , LA, T, F, B, RCr, RB, DA, were then orthogonal ized with success ive var ia tes being r e c a l c u l a t e d as r e s i d u a l s from mul t ip le regress ions upon e a r l i e r independent va r iab les (Eaton and Kyte, 1978; Nei lson and Eaton, 19B3). Y ie ld was then regressed upon these adjusted v a r i a b l e s . The R 2 for each of these adjusted orthogonal independent var iab les corresponds to i t s incremental con t r ibu t ion to y i e l d v a r i a t i o n during ontogenesis. Treatment and error sources of v a r i a t i o n for each orthogonal independent var iab le were p a r t i t i o n e d by ANOVA. The r e s u l t s of ANOVA were then used to a l l o c a t e R 2 p r o p o r t i o n a l l y (Table II) (Eaton et a l . , 1986). The r e s u l t s from ANOVA in the text re fer to the unadjusted var ia tes while the r e s u l t s from TDP, which incorporates ANOVA, re fer to the adjusted orthogonal v a r i a b l e s ( X i ) . RESULTS AND DISCUSSION ANOVA and TDP are not s t r i c t l y comparable because the procedures are appl ied to d i f f e r e n t v a r i a t e s , but the information about treatment e f f e c t s from each complement each other . ANOVA gives information about a var ia te which may be s i m i l a r to that for other a t t r i b u t e s upon which i t depends. TDP gives new information on a var ia te which cannot be 33 TABLE I Bum of i q u t r n f o r e f f e c t s of f e r t i l i z e r , PP333 and CCC on v e g e t a t i v e and y i e l d v a r i a t e s o f • t r a w b e r r y S o u r c t of v a r i a t i o n df C r 1 LA T F B RCr RB DA Y B l o c k e* 3# 15* 11* 9* 3# 10* 2 6* C u l t i v a r (C) 1 3» 2» 0 8* 7* 5* 1 1 1 F e r t i l i z e r <F) 1 3* 10* 0 0 1 2* 0 0 0 C o n t r o l v i . PP333 1 1 8* 1 1 0 16* 2t 10t 0 PP333 l o g l i n e a r 1 2 17* 0 0 0 24» 17t 0 17t PP333 l o g q u a d r a t i c 1 0 0 i 1 1 0 0 2t 1 PP333 d e v i a t i o n 1 0 0 0 0 0 0 0 2t 0 C o n t r o l v s . CCC 1 0 0 0 0 0 2* 0 0 1 215 v s . 1000 CCC 1 0 0 0 0 0 2* 0 0 0 PP333 v s . CCC 1 1 12* 0 0 0 14* 8* 13* 1 C X F 1 1 0 0 1 1 0 0 0 0 C X C o n t r o l v s . PP333 1 0 5# 0 0 1 0 0 1 0 C X PP333 l o g l i n e a r 1 3* 1* 3* 1 2* 0 0 1 1 C X PP333 l o g q u a d r a t i c 1 0 0 0 0 0 1* 0 0 0 C X PP333 d e v i a t i o n 1 0 0 0 0 0 0 0 2t 0 C X C o n t r o l v s . CCC 1 0 0 0 0 0 0 0 1 2t C X 215 v s . 1000 CCC 1 0 1* 0 0 0 0 1 0 0 C X PP333 v s . CCC 1 3* It 2* 5* 4* 0 0 2t 1 F X C o n t r o l v s . PP333 1 0 0 0 0 0 0 0 0 0 F X PP333 l o g l i n e a r 1 0 0 0 0 0 0 0 2t 0 F X PP333 l o g q u a d r a t i c 1 0 0 1 0 0 0 0 It 0 F X PP333 d e v i a t i o n 1 2» 1 1 1 2« 0 1 0 1 F X C o n t r o l v s . CCC ] 0 0 0 0 0 It 0 0 0 F X 215 v s . 1000 CCC 1 0 0 0 0 0 0 0 0 0 F X PP333 v s . CCC 1 0 I* 0 0 0 0 0 0 0 C X F X R e t a r d a n t 7 3 1 2 2 3 3« 2 4 5 E x p e r i m e n t a l E r r o r 155 69 34 72 66 68 2B 55 55 61 T o t a l U> 191 100 100 100 100 100 100 100 100 100 * Cr « number of c rowns per p l a n t , LA = l e a f a r e a per p a r e n t p l a n t l e u 3 ) , T = number of t r u s s e s per p l a n t , F = number of f l o w e r s per p l a n t , B • number of f r u i t s per p l a n t , RCr= number of r u n n e r c rowns per p l a n t , RB = number of r i p e f r u i t s pe r p l a n t , DA = number of a c h e n e s per f r u i t , Y = t o t a l f r e s h w e i g h t of f r u i t pe r p l a n t ( g ) . t P < 0.05. T o t a l sums of s q u a r e s were 118, 23571000, 100, 6608, 4729, 2264, 2652, 93202 and 57478 r e s p e c t i v e l y . 34 TABLE II Yi e l d v a r i a t i o n in glasshouse 'Totem' and 'Shuksan' strawberry plants expressed as incremental contributions of successive adjusted orthogonal vari a t e s to R2. Treatment e f f e c t s on varia t e s were p a r t i t i o n e d by ANOVA Adjusted y i e l d v ariables Source of v a r i a t i o n df Cr 1 X 2 x 3 X« X s X b X, Block 5 0.4i 0. 1 1.7» 0.1 0. 3 0. 0 1.3* C u l t i v a r (C) 1 0.1» 0. 1* 0 .6* 1.3* 0. 0 0. 1* 0.2 F e r t i l i z e r (F) 1 0.2# 0. 4* 0.4 0.0 0. 1 0.0 1.5* Control vs. PP333 1 0.0 0. 6* 0.1 0.0 0. 0 0. 1* 0.0 PP333 log l i n e a r 1 0.1 1. 3* 0.2 0.0 0. 0 0. 2* 0.9* PP333 log quadratic 1 0.0 0. 1« 0.3 0.0 0. 1 0. 1* 0.5* PP333 deviation 1 0.0 0. 0 0.1 0.0 0. 1 0. 0 0.2 Control vs. CCC 1 0.0 0. 0 0.1 0.0 0. 1 0. 1* 0.0 215 vs. 1000 CCC 1 0.0 0. 0 0.1 0.2* 0. 1 0. 1* 0.0 PP333 vs. CCC 1 0.0 0. 9# 0.0 0.0 0. 0 0. 1* 0.4* C X F e r t i l i z e r 1 0.0 0. 0 0.0 0.0 0. 0 0. 0 0.0 C X Control vs. PP333 1 0.0 0. 3« 0.0 0.0 0. 3 0. 1* 0.0 C X PP333 log l i n e a r 1 0.1» 0. 2* 0.3 0.0 0. 2 0. 1* 0.0 C X PP333 log quad 1 0.0 0. 0 0.3 0.0 0. 1 0. 1* 0.3* C X PP333 deviation 1 0.0 0. 0 0.1 0.0 0. 0 0. 0 0.0 C X Control vs. CCC 1 0.0 0. 0 0.2 0.0 0. 2 0. 0 0.0 C X 215 vs. 1000 CCC 1 0.0 0. 1* 0.1 0.1* 0. 2 0. 0 0.2 C X PP333 vs. CCC 1 0.1* 0. 1* 0.2 0.1* 0. 0 0. 1* 0.0 F X Control vs. PP333 1 0.0 0. 1* 0.1 0.0 0. 0 0. 0 0.0 F X PP333 log l i n e a r 1 0.0 0. 0 0.0 0.0 0. 0 0. 0 0.1 F X PP333 log quad 1 0.0 0. 0 0.3 0.0 0. 0 0. 0 0.0 F X PP333 deviations 1 0. 1* 0. 0 0.1 0.0 0. 1 0. 0 0.0 F X Control vs. CCC 1 0.0 0. 0 0.4 0.0 0. 1 0. 1* 0.0 F X 215 vs. 1000 CCC I 0.0 0. 0 0.0 0.0 0. 0 0. 0 0. 1 F X PP333 vs. CCC I 0.0 0. 1* 0.0 0.0 0. 0 0. 0 0.0 C X F X Retardant 7 0. 1 0. 0 1.0 0.3 0. 5 0. 1 0.5 Experimental Error 155 2.8 1.5 : 22.5 4.0 12. 9 0. 9 10.4 X X 0.2 0.3* 2.0 6.4* 0.3* 0.2* -1.8 1.0 0.4* 0.0 -2.8 0.2 1.3* 0.1* -2.3 0.0 1.3* 0.0 12.8 16.B* 0.4* 0.0 -0.4 0.9 0.0 0.0 -0.1 0.3 0.0 0.1 0.1 0.5 0.0 0.0 -0.5 0.0 1.3* 0.0 -1.9 0.8 0.0 0.0 -0.1 0.1 0.0 0.0 -0.6 0.2 0.0 0.0 -0.2 0.7 0.2 0.0 -0.5 0.3 0.2 0.0 -0.2 0.2 0.4* 0.0 1.4 2.2* 0.0 0.0 -0.5 0.2 0.1 0.0 0.6 1.4 0.0 0.0 -0.2 0.0 0.1 0.0 -0.2 0.0 0.0 0.0 -0.2 0.2 0.0 0.0 1.0 1.3 0.0 0.1 -0.5 0.0 0.1 0.0 -0.3 0.0 0.1 0.1 0.0 0.3 0.2 0.3 1.7 4.7 9.4 3.1 -6.3 61.2 Total Q> 191 4.1* 5.9*29.1* 6.3*15.6* 1.9*16.8*15.8* 4.5* 0.0 100.0 'Cr = number of crowns per plant, X 2 = adjusted leaf area (cm2) per plant, X s = adjusted number of trusses per plant, X , « adjusted number of flowers per plant, X s c adjusted number of f r u i t s per plant, X 6 = adjusted number of runner crowns per plant, X7 = adjusted number of ri p e f r u i t s per plant, > X e = adjusted number of developed achenes per f r u i t , Res = residual v a r i a t i o n ] X X = v a r i a t i o n due to cross-products between variables) Y • t o t a l fresh weight of f r u i t per plant (g). * P < 0.05. Si g n i f i c a n c e in the treatment row r e f e r s to ANOVA and in the t o t a l row refer s to regression a n a l y s i s . 35 predic ted from e a r l i e r va r ia tes in the developmental or a n a l y t i c sequence. With TDP the modi f ica t ion of y i e l d components by treatments i s examined and the assumed pathway by which treatments in f luence y i e l d i s c l a r i f i e d . C u l t i v a r and treatment e f f e c t s were detected in t h i s study for both unadjusted var ia tes with ANOVA and for adjusted var ia tes with TDP. In a d d i t i o n , each of the orthogonal independent var ia tes contr ibuted s i g n i f i c a n t l y to the regress ion model descr ib ing sources of y i e l d v a r i a t i o n (Table I I ) . A. Number of crowns Adjusted crown number accounted for 4.IX of y i e l d v a r i a t i o n . The high rate of NPK increased number of crowns s l i g h t l y (Table I I I ) . CCC had no e f fec t on crown branching poss ib ly because the rates of CCC used in our study were too low (6ut t r idge , 1966). 'Totem' had more crowns than 'Bhuksan' and the number of crowns for 'Totem' increased with PP333 concentrat ions (Table IV). Crown number was increased as a r e s u l t of a PP333-induced decrease in runnering in another study (Braun and Garth, 19B6) and c u l t i v a r d i f f e rences were a lso observed. The importance of number of crowns as a cont r ibutor to y i e l d v a r i a t i o n would be expected to increase in subsequent seasons. B. Leaf area » Adjusted leaf area accounted for 5.9X of y i e l d v a r i a t i o n . S imi lar to the c u l t i v a r d i f f e rences in response to PP333 observed by others (Atkinson et a l . , 19B5), leaf area and adjusted leaf area for parent p lants were decreased by PP333 but more for 'Totem' than 'Shuksan' (Table IV). High NPK increased both leaf area and adjusted leaf area and t h i s promotive e f fec t was greater for CCC treated plants r e l a t i v e to PP333 TABLE III E f fec t of f e r t i l i z e r rate on unadjusted and adjusted orthogonal var ia tes of strawberry 1 20N-8.7P-16.6K (mg/pot) C r 2 RCr X * RB XT DA X e 45 2.1 4.5 -0 .3 5.4 0.6 29.4 -13.9 180 2.4 5.4 0.3 5.7 -0 .6 30.0 13.9 S ign i f i cance • « ««* NS NS «*« NS « 'See Tables I and II for ANOVA. 2 C r = number of crowns per p l a n t , RCr, X & • unadjusted and adjusted number of runner crowns per pi ant, RB., X 7 = unadjusted and adjusted number of r ipe f r u i t s per p lant , DA, X B unad jus ted and adjusted number of developed achenes per f r u i t , NS = Not s i g n i f i c a n t , or « P < 0.05, »« P < 0.01, * « * P < 0.001. 37 TABLE IV Effect of PP333 and CCC on unadjusted and adjusted orthogonal variates of strawberry 1 Treatment (ag I" 1) PP333 0 10 46 215 1000 0 215 1000 Tot tn Cr 2 LA X. B RCr X* RB I T DA 2.2 2.2 2.3 2.B 2.9 1568 1315 1210 954 632 2.2 14B5 2.1 1524 2.1 1391 370 116 -1 -333 -666 286 336 203 1.1 1.3 1.2 1.2 1.6 -0.1 0.1 -0.1 -0 .4 0.2 -0.1 -0.1 -0.1 9.7 12.7 10.9 11.3 15.1 9.2 9.4 9.1 1.0 3.1 1.9 1.8 2.3 0.5 1.3 1.1 B. 1 10.4 9.3 9.B 11.9 8.1 7.B 8.5 -0.4 -0.4 -0.1 •0.3 -0.3 0.0 -0.6 0.6 6.4 9.6 3.0 0.4 0.0 7.2 6.3 4.5 -0.2 0.7 -1.7 -2.1 -0.3 O.B -0.3 -1.6 6.5 -0 .4 12.1 6.9 -0 .2 36.9 5.B 0.1 43.8 0.5 46.4 -2 .5 43.5 5.0 1.6 -61 50 96 32 -51 . 1 7.3 6.5 7.3 0.2 16.9 0.0 10.6 -21 •63 0.6 13.0 -74 16.7 .2 27.7 .2 27.2 .1 21.4 .5 5.9 .3 22.2 .4 16.2 .0 19.0 Treatment (•q I ' M PP333 Shuksan CCC Cr LA X 2 T X 3 F X . B X s RCr X* RB X 7 DA Xe Y 0 1.9 1141 -25 0.9 -0.1 6.1 -1 .6 6.0 0.7 6.6 2.9 5.6 0.0 23.5 -26.9 22.6 10 2.3 1267 57 1.5 0.3 6.8 - 2 . 3 7.6 0.4 7.0 1.7 7.2 0.7 41.7 61.4 36.5 46 2.0 1151 -26 1.2 0.1 6.9 -2.1 5.9 -0.1 5.5 0.2 4.7 0. 1 35.1 35.3 23.2 215 2.0 1015 -162 1.1 0.0 6.3 - 1 . 9 5.2 -0.1 2.6 - 2 . 0 3.4 0.3 53.2 58.7 IB. 6 1000 2.1 655 -333 1.0 0.0 5.5 - 2 . 3 4.1 - 0 . 5 0.3 -3 .7 0.3 -0 .9 21.6 -16 .9 l .B 0 2.2 1324 125 1.2 0.0 6.5 - 0 . 5 6.8 -0 .6 6.4 2.6 6.2 0.3 19.2 -44.9 19.3 215 2.0 1134 -44 1.3 0. 1 10.3 1.0 9.2 0.5 7.5 2.6 8.0 1.1 28.6 7.0 40.0 1000 2.3 1317 96 1.6 0.4 6.6 - 3 . 3 7.8 0.4 5.6 0.5 6.4 0.0 29.1 1.2 30.7 1 See tab les 1 and 2 for a n a l y s i s of v a r i a n c e . 2 C r = number of crowns per p lant ) LA, X 2 = unadjusted , adjusted leaf area (cm 2) per p lant ) T, X 3 a unad justed , ad justed number of t r u s s e s per pi ant | F , X. = unadjusted, adjusted nunber of f lowers per p lant ) B, X s • unad justed , adjusted number of f r u i t s per p lant ) RCr, X* • unad jus ted , adjusted number of runner crowns per p lant ) RB, Xy = unadjusted , adjusted number of r i p e f r u i t s per p lant ) DA, X„ = unadjusted , adjusted nuaber of developed achenes per f r u i t , Res » r e s i d u a l v a r i a t i o n ) XX * v a r i a t i o n due to c r o s s - p r o d u c t s between v a r i a b l e s ! Y = t o t a l f resh weight of f r u i t per p lant (g) . 38 t reated p lants (T tb l t V) . High NPK and PP333 s l i g h t l y increased leaf number and delayed leaf senescence but PP333 at 215 mg l - 1 decreased area per leaf (HcArthur and Eaton, 1987a or Chapter 3) . For adjusted leaf a rea , the promotive e f fec t of the high rate of NPK Mas decreased for PP333 t reated p lants compared to c o n t r o l s . Plants t reated with the 46 mg 1~* ra te of PP333 plus high NPK had s a t i s f a c t o r y canopy development, greater leaf area and fewer runner crowns than cont ro l p lants with low NPK (Table V) . The promotive e f fec t of high NPK was genera l ly los t and canopy development severely r e s t r i c t e d with PP333 at 215 mg 1"». C. Number of t russes The most substan t ia l cont r ibutor to y i e l d v a r i a t i o n in TDP was the adjusted number of t russes per plant which accounted for 29.1%, most of which was experimental e r r o r . Truss number per plant was s l i g h t l y i n -creased by PP333 at high rates for 'Totem' but was increased for 'Shuksan' only at low rates (Table IV). Af ter taking into account d i f f e rences in crown number and leaf area , there were no treatment e f f e c t s for adjusted t russ number. 'Totem' had a lower adjusted t russ number than 'Shuksan'which ind ica tes that although 'Totem' had more crowns, the number of t russes per crown was greater for 'Shuksan' (Table VI) . D. Number of f lowers Adjusted flower number per plant accounted for 6.3X of y i e l d v a r i a -t ion a f ter previous v a r i a b l e s had been cons idered . Both ANOVA and TDP showed 'Totem' had more f lowers than 'Shuksan' thus , i n d i c a t i n g 'Totem' had more f lowers per t russ (Table VI) . Both analyses ind ica ted a s l i g h t TABLE V Ef fect of PP333 end CCC on unadjusted end adjusted orthogonal var ia tes of strawberry 1 20N-B.7P-t6.eK <45 mg/pot) Treatment L A 2 X 2 B X 3 RCr DA Xe PP333 (mg 1" 0 1212 35 6.B 0. 1 6.9 1.4 16.5 -58.7 10 1226 27 9.0 0.1 5.8 0.8 37.0 51.5 46 1030 -114 5.6 -0 .5 3.6 -1 .6 37.3 45.6 215 959 -273 8. 1 0.3 1.1 -2.4 45.7 43.5 1000 721 -47B 6.9 -0 .7 0.0 -2.7 43.2 -33.4 CCC (mg I"') 0 1243 55 6.6 -0.2 6.7 1.2 17.6 -54.6 215 1202 36 8.4 -0.4 6.8 1.5 16.4 -59.6 1000 1159 -18 7.7 0.4 5. 1 -0.2 21.8 -45.2 20N-I 3.7P-16.6K (180 mg/pot) Treatment LA X * B X s RCr X * DA X e PP333 (mg 1" 1 ) 0 149B 310 7.3 0.2 B. 1 1.4 19. 1 -29.2 10 1356 146 9.2 -0 . 1 7.0 1.6 41.6 80. 1 46 1330 87 9.6 0.3 4.9 -0 . 1 41.6 85.9 215 1010 -222 6.9 0. 1 2. 1 - l . B 53.9 47.2 1000 766 -521 9. 1 -0 . 1 0.3 -1.4 21.9 -37.0 CCC (mg I"') 0 1566 356 8.3 -0 .3 8.9 2.5 18.5 -11.6 215 1456 257 8.5 0.3 7.0 0.8 23.2 3. 2 1000 1548 316 8.6 0.6 5.3 -1.0 20.2 ••21.b 'See Tables 1 and II for ANOVA. ~A, X z = unadjusted and adjusted 1 leaf area (cm') per p lant , B, X r , = unadjusted and adjusted number of f r u i t s per p lan t , RCr, X & = unadjusted and adjusted number of runner crowns per p lan t , DA, X s = unadjusted and adjusted number of developed achenes per f ru i t , TABLE VI Cu l t i va r d i f fe rences in unadjusted and adjusted orthogonal var iates of strawberry Cu l t i va r T l X 3 F X * DA X, Totem 1.2 -0 . 1 10.9 1.6 27.9 -11.6 Shuksan 1.2 0.1 7.6 -1.6 31.5 11.6 S ign i f i cance NS • «•• # # » NS * l T , X 3 - unadjusted and adjusted number of trusses per p lant , F , X * - unadjusted and adjusted number of f lowers per p lan t , DA, Xe - unadjusted and adjusted number of developed achenes per f r u i t . NS = Not s i g n i f i c a n t , or » P < 0.05, »* P < 0.01, * « * P < 0.001. 41 increase in flower number for 'Totem' t reated with PP333 and a s im i la r increase for 'Shuksan' but with CCC instead (Table IV). These r e s u l t s i n d i c a t e the decreased vegetat ive growth caused by the growth retardants allowed improved development of l a te r developed flower buds. The large proport ion for experimental error (100R2 «= 4.OX) poss ib ly r e l a t e s to f a c t o r s such as plant vigour during the previous induct ive cyc le (Robertson and Hood, 1954). Improved evaluat ion of treatment e f f e c t s on f lowering would requi re a period of short days and rest to induce reproduct ive a t t r i b u t e s . E. Number of f r u i t Adjusted f r u i t number per plant accounted for 15.6X of y i e l d v a r i a -t i o n . 'Totem' produced more f r u i t s than 'Shuksan' and f r u i t number for 'Shuksan' decreased with increas ing rates of PP333 (Table IV). F e r t i l i -zer rate appeared to have some i n t e r a c t i v e e f fec t with PP333 a l s o , with high NPK genera l ly increas ing f r u i t number (Table V) . There was no c u l t i v a r or treatment e f fec t upon adjusted f r u i t number af ter accounting for the cont r ibu t ion of previous var iab les such as flower number (Table V) . An ANOVA (not shown) detected no s i g n i f i c a n t c u l t i v a r or treatment e f f e c t s upon the number of be r r i es per flower and these f ind ing together i n d i c a t e no treatment e f f e c t s on or c u l t i v a r d i f f e rences for f r u i t set that in f luenced y i e l d v a r i a t i o n . The large res idua l var iance in the adjusted number of f r u i t s (Table II) may r e f l e c t the l im i ted p o l l i n a t i o n under glasshouse c o n d i t i o n s . F. Number of runner crowns The adjusted number of runner crowns or p l a n t l e t s produced per plant made a small but s i g n i f i c a n t con t r ibu t ion to y i e l d v a r i a t i o n 42 < 1OOR3-1.951). The number of runner crowns was increased by NPK (Table I I I) . This i s s i m i l a r to other reports of improved runnering with the use of f e r t i l i z e r s (Blat t and Crouse, 1970$ T a f a z o l i and Bhaybany, 1978; Breen and Mar t in , 1981; McArthur and Eaton, 19B7a or Chapter 3 ) . However, TDP ind ica ted no such e f fec t upon adjusted runner crowns per plant s ince runner formation depended upon new leaf development which was a lso promoted by high NPK. An ANOVA (not shown) a lso ind icated no s i g n i f i c a n t e f fec t of NPK rate on runners per l e a f . Increased runnering or runner crown production in our study then, appears to be an aspect of increased vegetat ive vigour and i t i s u n l i k e l y that the observed reponse to high NPK was as a r e s u l t of an in f luence on f a c t o r s that decrease ap ica l dominance or contro l l a t e r a l shoot morphology. The promotive e f fec t of high NPK on runner crown formation was decreased by CCC (Table V) . This e f fec t was not observed on the number of runners (McArthur and Eaton, 19B7a or Chapter 3) but for both unadjusted and adjusted runner crown number. CCC appeared to delay development of runner crowns. E i ther of CCC or PP333 decreased both unadjusted and adjusted runner crown number, but PP333 was more e f f e c t i v e than CCC. 'Totem' had a smaller number of unadjusted or adjusted runner crowns than 'Shuksan' because of i t s l a t e r peak of runner production (McArthur and Eaton, 1987a or Chapter 3) . Perhaps because of t h i s la te r runner product ion a l s o , 'Totem' was more responsive than 'Shuksan' to PP333. PP333 near ly prevented production of runner crowns at 215 mg l " 1 in 'Totem' but at 1000 mg l - 1 in 'Shuksan' (Table IV). Comparison of PP333 and CCC on the adjusted number of runner crowns ind ica ted 'Totem' was more responsive to both PP333 and CCC than 'Shuksan ' . 43 6. Number of r ipe f r u i t * The adjusted number of f r u i t s that r ipened per plant accounted for 16.8% of y i e l d v a r i a t i o n . Both unadjusted and adjusted nuabers of r ipe f r u i t s decreased with increas ing rates of PP333 but not with CCC (Table VI I ) . P lants t reated with PP333 had fewer r i p e f r u i t s than untreated p l a n t s . TDP detected a s l i g h t increase in adjusted r i p e f r u i t number at low rates of PP333, e s p e c i a l l y for 'Totem' , but there was a large decrease at 1000 mg l - 1 (Table IV). The percentage of r ipe f r u i t s per f r u i t (ANOVA not shown) was B5X in cont ro ls and 56X in PP333 treated p l a n t s , i n d i c a t i n g a s i g n i f i c a n t (p=0.001) delay in r ipen ing due to PP333. That NPK delayed r ipening a lso was ind ica ted by TDP which showed a s i g n i f i c a n t decrease in adjusted number of r ipe f r u i t s at the high rate of NPK (Table I I I ) . In sunf lower, a s i m i l a r N e f fec t upon delayed f i n a l y i e l d was a t t r ibu ted to increased l e v e l s of endogenous cy tok in in (Wagner and H i c h a e l , 1971). H. Number of achenes per f r u i t Adjusted achene number per f r u i t accounted for 15.8V. of y i e l d v a r i a -t i o n . Both unadjusted and adjusted achene numbers per f r u i t were increased by PP333 (Table VII) with a high at 215 mg l " 1 of PP333 but not by CCC. Decreased seed abort ion caused by PP333 may have been a fac tor in our study as reported in ryegrass (Hampton and Hebblethwaite, 1985). The adjusted number of achenes per f r u i t was greater for 'Shuksan' than 'Totem' (Table VI) and was increased in 'Shuksan' by CCC but decreased in 'Totem' (Table IV). PP333 increased unadjusted achene number but at the high NPK rate a sharp decrease was observed at 1000 eg l " 1 . This was l i k e l y a r e s u l t of a general i n h i b i t i o n of f r u i t r ipen ing by both NPK and PP333 (Table V) . Adjusted achene number per TABLE VII E f fec t of PP333 and CCC on unadjusted and adjusted orthogonal var ia tes of strawberry 1 Treatment RB 2 X 7 DA X e Y PP333 (mg I"1) 0 6.1 -0.2 17.5 -44.0 20.6 10 7.0 0.3 39.5 65. B 32. 1 46 5.3 0.1 39.5 65.7 25.2 215 4.2 0.4 49.5 45.4 20. 1 1000 1.0 -1.7 33.0 -35.2 3.9 CCC (mg 1-M 0 6.7 0.3 1B.0 -33. 1 20.7 215 7.3 0.5 20.0 -28.2 25. 1 1000 6.B 0.3 21.0 -36.4 24.9 •See Tables I and II for ANOVA. 2 R B , X 7 = unadjusted and adjusted number of r ipe f r u i t s per p lan t , DA, X e = unadjusted and adjusted number of developed achenes per f r u i t , Y = tota l fresh weight of f r u i t per plant (g). 45 f r u i t increased for p lants t reated with the high rate of NPK (Table I I I ) , and R a y be re la ted to our observat ion that high NPK a lso delayed f r u i t r i p e n i n g . The s i m i l a r e f f e c t s of high NPK and PP333 on achene number and f r u i t r ipen ing suggest that both n a y increase the leve l of endogenous c y t o k i n i n s . Increased N status has been cor re la ted with increased cy tok in in l e v e l s in shoots (Noolley and Wareing, 1972) and seeds, and delays in seed r ipening (Wagner and Michae l , 1971). Both CCC (Skene, 1968) and the t r i a z o l e fung ic ide t r iadimefon (Fletcher and Arno ld , 1986) have been reported to increase endogenous l e v e l s of cy tok in ins in p lan ts . Like PP333, both CCC and tr iadimefon are i n h i b i t o r s of GA b iosynthes is and have s i m i l a r e f f e c t s . I. Y ie ld Response The dec l ine in f resh weight of r ipe f r u i t per plant (y ie ld) with increas ing rates of PP333 (Table VII) accounted for 16.BX of the v a r i a -t ion in y i e l d . Although y i e l d for PP333 treated plants was not s i g n i f i -cant ly d i f f e r e n t from cont ro ls or p lants t reated with CCC, PP333 at 1000 mg l " 1 s u b s t a n t i a l l y decreased y i e l d . CCC increased y i e l d for 'Shuksan' but decreased i t s l i g h t l y for 'Totem' (Table IV). CCC has decreased runnering and promoted crown formation but not y i e l d during the season in which i t was appl ied (Gut t r idge, 1966). Y i e l d increases in fo l lowing seasons were a t t r ibu ted to t h i s e f fec t on number of crowns. No e f fec t of NPK upon y i e l d was ev ident . Varying rates of f e r t i l i z e r can increase current season's y i e l d in strawberry, but r e s u l t s depend on c u l t i v a r , r a t e , t im ing , amounts and NPK r a t i o s used ( K i r s c h , 1959; Voth et a l . , 1961; Rodgers et a l . , 1985). Using TDP, i t was p o s s i b l e to i d e n t i f y the most important 46 cont r ibutor to y i e l d v a r i a t i o n from among the adjuated y i e l d v a r i a b l e s . This component Mas the number of trusses per plant fol lowed by the number of r ipe f r u i t s per p l a n t , number of achenes per f r u i t and the number of f r u i t s per plant (Table I I) . The other adjusted var iab les a l l made s i g n i f i c a n t con t r ibu t ions but account for minor amounts of y i e l d v a r i a t i o n . PP333 accounted for a substan t ia l port ion of y i e l d va r ia t ion and TDP Mas useful in c l a r i f y i n g how PP333 in f luenced y i e l d i n d i r e c t l y through i t s e f f e c t s on y i e l d v a r i a b l e s . Delayed f r u i t r ipen ing by PP333 l i k e l y accounts for the decrease in y i e l d of f resh Height of r ipe f r u i t in our study. Stang and Weis (1964) a lso found no e f fec t on y i e l d with low rates of PP333 but did note a delay in f r u i t r i p e n i n g . Component compensation was observed and, for example, PP333 increased the adjusted number of achenes per f r u i t but decreased many of the e a r l i e r adjusted v a r i a b l e s . The large p o s i t i v e value for PP333 trend ana lys is i n d i c a t e s that PP333 l i k e l y a f fec ted many of the components in a s i m i l a r f a s h i o n , poss ib ly due to i n h i b i t i o n of GA b i o s y n t h e s i s . The small but s t i l l s i g n i f i c a n t e f fec t of PP333 on the adjusted var iab les number of runner crowns, number of r ipe f r u i t s and achene number per f r u i t suggests PP333 had an a d d i t i o n a l , d i f f e r e n t effect other than the general one on GA b iosynthes is suggested here. CCC increased the number of achenes per f r u i t and t h i s e f fec t accounted for the higher y i e l d of 'Shuksan' treated with CCC in^the present study. Neither c u l t i v a r nor f e r t i l i z e r rate a f fected y i e l d , but component compensation was i n d i c a t e d . Thus, Mhile 'Totem' had more crowns and f lowers per p l a n t , 'Shuksan' had more t russes and achenes per f r u i t , the l a t t e r observat ion i n d i c a t i n g better f r u i t se t . These c u l t i v a r d i f f e rences o f fse t each other so that y i e l d was not a f f e c t e d . In a s i m i l a r f a s h i o n , the decrease in the number of ripe f r u i t caused by 47 the higher NPK rate appeared to be o f fse t in y i e l d by an increase in achenes per f r u i t . In genera l , vegetat ive growth was more responsive than f r u i t growth to low rates of PP333. Since PP333 at 46 ng l ' 1 and at e i ther NPK rate decreased runnering without causing any detr imental e f f e c t s to canopy development or decreasing y i e l d , PP333 does appear to have potent ia l as an a l t e r n a t i v e to pruning for contro l of runnering in strawberry. Hence, PP333 might be used as an adjunct to high f e r t i l i z e r rates to promote rapid canopy development without the problem of excessive runner ing. The e a r l i e r report of i n h i b i t i o n of strawberry po l len germinat ion, a long period of s o i l a c t i v i t y for PP333 residues and detrimental e f f e c t s of PP333 at high concentrat ions (McArthur and Eaton, 1987a or Chapter 3) suggests some caution must be exerc ised in f i e l d a p p l i c a t i o n s . CHAPTER 5 CRANBERRY RESPONSE TO GROWTH REGULATORS, FERTILIZER AND SOIL TYPE INTRODUCTION Rapid canopy establishment and promotion of f lowering are two major ob jec t ives that can c o n f l i c t with each other in f r u i t crop systems. In cranberry bogs f e r t i l i z e r use i s essen t ia l to obtain an optimum density of upr ights and to promote the i r f lowering of them. However, vine growth i s more responsive to f e r t i l i z e r than upright growth (Eck, 1971) and increas ing rates of ni trogen can decrease the number of f lowering upr ights and y i e l d (Eaton, 1971a; Eck, 1976). The cranberry has a narrow range between d e f i c i e n c y and overst imulat ion of vine growth (Torio and Eck, 1969) which may vary with environmental condi t ions and the age of the bog (Dana, 196Ba, 1968b). Control over the balance between the growth of product ive upr ights and vines would be of commercial b e n e f i t . Mineral nut r ients may in f luence some' aspects of plant growth by a l t e r i n g the l e v e l s and r a t i o s of endogenous plant growth regulators (Rajagopal and Rao, 1974; Horgan and Wareing, 1980; Dar ra l l and Wareing, 1981). Mineral n u t r i t i o n and growth regula tors appear to be involved in the contro l of l a t e r a l shoot morphology (Mclntyre, 1968; Woolley and Wareing, 1972). G i b b e r e l l i n s (GA) or GA- l i ke substances are impl icated as promotors of shoot growth in the cranberry (Eady and Eaton, 1972 ). Appl ied GA 3 increases vine and upright e longat ion and decreases flower bud set in a manner s i m i l a r to that of o v e r - f e r t i l i z a t i o n with ni trogen (Devlin and Demoranvi11e, 1967; Mainland and Eck, 1968). Chemical regu la t ion of vegetat ive growth has been invest iga ted ex tens ive ly for f r u i t t rees (Ouinlan, 1981; Wi l l iams, 1984) and 49 ornamentals (Cathey, 1975). Research on i n h i b i t o r s of 6A b iosynthes is such as SADH and PP333 i n d i c a t e good growth contro l and promotion of f lowering can be achieved with PP333 at very low rates r e l a t i v e to other growth retardants such as SADH (Shearing et a l . , 1986). PP333 or other retardants nay be of value for cranberry systems; for example, SADH appl ied to f i e l d cranberry p lants decreased winter damage (Doughty and Scheer, 1969), s l i g h t l y decreased upright l eng th , improved flower bud set and did not a f fec t y i e l d during the current season (Lenhardt and Eaton, 1976). However, the dose-response r e l a t i o n s h i p of PP333 for cranberry and the poss ib le modifying e f fec t of f e r t i l i z e r rate on PP333 have not been thoroughly i n v e s t i g a t e d . This study was undertaken to determine the e f f e c t s of several growth re ta rdan ts , f e r t i l i z e r rate and type of s o i l on vegetat ive growth of two commercial cranberry c u l t i v a r s grown in a g lasshouse. In the f i r s t experiment, SADH was shown to be r e l a t i v e l y i n e f f e c t i v e in comparison with PP333 and was not included in l a te r experiments. The rates of PP333 and f e r t i l i z e r , and type of s o i l were var ied to determine the treatment i n t e r a c t i o n s . The f i n a l ob jec t ive was to determine i f the growth response to PP333 could be modified by B A 3 ; AC 94,377; NAA; or ABA. MATERIALS AND METHODS A. Experiment 1. 1984 Treatments cons is ted of a l l 20 combinations of 2 c u l t i v a r s and 6 l e v e l s of PP333 or 4 l e v e l s of SADH, randomly arranged in each of 8 complete b locks . On 2 Feb. 1984, 1 to 2 -year -o ld wood of runners of ' M c F a r l i n ' and 'Ben Lear ' cranberry were c o l l e c t e d from a commercial cranberry f i e l d . 50 C u t t i n g ! 8-cm long w i n i n s i r t i d 4-cn dttp in sand in • hiatad glasshouse • i c t bid ind allowed to root . On 10 Mar. , each rooted cut t ing wac placed in sand in a 9-cm pot on a tray of f i n e sand. Trays were placed on a bench with d iurna l temperatures between 16 and 28°C. One cool white f luorescent lamp (100 N) per block was set 28-cm above the s h o o t - t i p s to give a d a i l y 16-hr photoper iod. At the end of the experiment, photosynthet ic photon f lux densi ty (PPFD) was measured at s h o o t - t i p height to be 350/tmol m~s s " 1 . Beginning 16 Mar. , p lants were f e r t i l i z e d weekly for 14 weeks with 20 mg/pot of 20N-8.7P-16.6K (67. as N03" + 47. as NH4* + 10'/. as urea) with micronut r ien ts . Growth retardants in a 0.17. Tween'20 so lu t ion were appl ied as shoot and sand sprays to runoff (6 ml/pot) during the nyctoperiod on 6 and 27 A p r i l . The PP333 used was a 257. a . i . suspension (ICI Americas) and was appl ied at concentrat ions of 0, 75, 150, 300, 600, 1200 mg l _ l a . i . The SADH used was the 5X B-Nine formulat ion and was appl ied at 0, 300, 600, 1200 mg l _ l a . i . Pe r iod ic measurement of the main shoot ( f i r s t primary) was made and plants were allowed to develop u n t i l a f i n a l harvest in l a te J u l y . Bud set and flower bud set were r e s p e c t i v e l y the percentage of shoots with a terminal bud and the percentage of those terminal buds that were f l o r a l . A l l data were examined with ana lys is of var iance (ANOVA). Separate contro l values for SADH and PP333 were pooled and therefore not a l l cont rasts were or thogonal . B. Experiment 2. 19B4 Treatments cons is ted of a l l 32 combinations of 2 c u l t i v a r s , 2 s o i l types , 2 l e v e l s of f e r t i l i z e r and 4 l e v e l s of PP333, randomly arranged in each of 4 complete b locks . Rooted runner cu t t ings of ' H c F a r l i n ' and 'Ben Lear ' cranberry were 51 obtained i s in experiment 1. On 25 Mar. 1984, each rooted cu t t ing Mas placed in a B-cm pot with e i ther peat and s o i l (112 v/v) or sand and soi l (1:2 v/v) and then moved to the glasshouse bench of experiment one. Two cool Mhite f luorescent lamps (100 H each) per block Mere set 28-cm above s h o o t - t i p s to give a d a i l y 16-hr photoperiod u n t i l Oct . a f ter which plants received no supplemental l i g h t i n g . P lants Mere f e r t i l i z e d f o r t n i g h t l y for 30 Meeks beginning 1 Apr. Mith e i ther 8 mg/pot or 30 mg/pot 20N-B.7P-16.6K with micronut r ien ts . On 10 June, pots received a 100-ml s o i l drench of a OA'/, Tween'20 so lu t ion conta in ing 0, 1.25, 2.50 or 5.00 mg a . i . of PP333. On 31 A u g . , a l l ap ica l buds were c o l l e c t e d and examined for f lowers . Plants were allowed to develop fur ther u n t i l Apr. 1985, at which time fur ther bud set was determined. A l l data were examined with ANOVA. (i) Bioassay for PP333 After the f i n a l harvest , pot s o i l for c u l t i v a r s and NPK rates were pooled , and bioassayed for PP333 using the procedure prev ious ly reported (McArthur and Eaton, 1987a or Chapter 3) . The rate of PP333 used for the bioassay standard was 6 ml of 0, 25, 50 or 100 mg I"1 a . i . Mean s o i l pH was 5.4 for sandy s o i l and 5.1 for peaty s o i l . PP333 was observed to decrease seed germination for the bioassay p l a n t , so a fur ther study was undertaken. In each of 4 complete b l o c k s , a l l 8 combinations of PP3333 at 0, 25, 50 or 100 mg l - 1 and BA 3 at 0 or 50 mg l " 1 Mere appl ied to pe t r i d ishes conta in ing f i l t e r paper and 25 seeds of B. napus 'Wester ' . Each dish received 5 ml of treatment so lu t ion and was incubated for 48 hr at 28 °C . Percentage germination and length of 5 seedl ings were determined for each pe t r i d i s h . C. Experiment 3. 1985 Treatments cons is ted of a l l 18 combinations of 2 c u l t i v a r s , 3 l eve ls 52 of PP333 and 3 l e v e l s of t i t h i r B A 3 , AC 94,377, NAA or ABA randomly arranged in each of 4 complete b l o c k s . On 9 Hay 19B5, 1-year-old wood of runners and upr ights of 'Ben Lear ' and ' H c F a r l i n ' cranberry were c o l l e c t e d and rooted as in experiment 1. On 5 J u l y , 2 rooted cut t ings or upr ights were placed into each 9-cm pot conta in ing p e a t i s o i l (1:4) . Cut t ings and upr ights were placed in separate blocks on a glasshouse bench without supplemental l i g h t i n g . PPFD was measured at 4-hr i n t e r v a l s during 20 Aug. and averaged 250yumo) s ~ l m~2 with a maximum of eOOy^ mol s - i m - 2 at s h o o t - t i p he ight . Plants were f e r t i l i z e d weekly with 20 mg/pot of 20N-8.7P-16.aK with micronut r ien ts . PP333 at 0, 50 or 100 mg l " 1 a . i . was appl ied during the mornings of 20 and 27 J u l y . During the nyctoperiod of the same days, 0, 50 or 100 mg l - t of 8 A 3 , AC 94,377, NAA or ABA was a lso a p p l i e d . Growth regula tors were appl ied in a 0.1X Tween'20 so lu t ion as a 10-ml shoot + s o i l drench per plant (20 ml /po t ) . 6 A 3 , NAA and ABA were obtained from Sigma and AC 94,377 was a 507. W.P. obtained from American Cyanamid C o . , U .S .A . The length of the main shoot ( f i r s t primary) to develop and bud set were measured non -des t ruc t i ve ly at 3-weeks i n t e r v a l s and the shoots harvested 23 Sept. 1985. A l l data were examined with ANOVA. RESULTS AND DISCUSSION A. Experiment 1. 1984 Shoot and root dry weights, shoot l eng th , and area per leaf were greater for ' H c F a r l i n ' than 'Ben Lear ' (Table I). No c u l t i v a r d i f fe rence for shoot:root r a t i o was ev ident . The to ta l amount of branching was greater for 'Ben Lear ' as i t developed more branches per primary branch even though ' H c F a r l i n ' had more primary branches per c u t t i n g . In a study 53 TABLE I Vegetative a t t r ibu te ! of rooted runner cutt ings of 'McFar l in ' and 'Ben Lear' cranberry in Experiment i Primary Branches Mean branches per shoot Leaves Area Shoot Root per primary length per per leaf dry wt dry wt Cul t ivar cutt ing branch (cm) shoot (cm2) (mg) (mg) McFarlin 6 1 14 42 0.22 1429 541 Ben Lear 5 2 10 26 0.21 1174 452 Signi f icance • • • • •• • • • • • « P < 0.05, »» P < 0.01, »»« P < 0.001. 54 comparing c u l t i v a r d i f f e r e n c e s in growth habit in the cranberry , ' H c F a r l i n ' produced more upr ights on vine growth that has aged several years than on recent vine growth compared to 'Bergman' (Tallman and Eaton, 1976). The rate of e longat ion for the main shoot increased over time for cont ro l and SADH-treated p lants but decreased for p lants t reated with PP333 (Table II) . The rate of shoot e longat ion was decreased within 3 weeks of a p p l i c a t i o n of PP333 but not of SADH. Bud formation occurred in l a te May and was more common on 'Ben Lear ' than on ' H c F a r l i n ' p lan ts . PP333 increased the number of buds per plant while SADH did not. The buds on contro l and SADH-treated plants renewed growth within several weeks of bud s e t , but did not do so on PP333-treated p l a n t s . Such growth f lushes have been reported for highbush blueberry (Sough et a l . , 1978) and are not uncommon on other woody plants (Kramer and Kozlowski , 1979). SADH had no e f fec t on branching, percentage bud set or root dry weight (Tables III and IV). The e f f e c t s of SADH on shoot dry weight and area per leaf were v a r i a b l e , as were d i f f e rences in c u l t i v a r response to SADH for shoot length and leaves per shoot. Weak or t r a n s i t o r y e f f e c t s on shoot growth of glasshouse cranberry p lants t reated with repeat sprays of SADH at 1500 mg l " 1 with no surfactant have been observed (Lenhardt, 1976). Repeated sprays at the same rate with a sur factant s l i g h t l y decreased length and increased flower bud set of cranberry upr ights in the f i e l d (Lenhardt and Eaton, 1976). Rates of SADH in the present study were perhaps too low to e l i c i t responses reported with other woody plants (Batjer et a l . , 1964; Doughty and Scheer, 1969). Plant growth was responsive to PP333 and even the lowest rate decreased root and shoot dry weight by approximately 50% (Table I I I) . The shooti root r a t i o was decreased but to a l esser extent , i n d i c a t i n g a 55 TABLE II Rate of primary shoot elongation and number of buds set per plant for rooted runner cuttings of 'McFar l in ' and 'Ben Lear' cranberry treated with SADH and PP333 in Experiment 1 Rate of shoot elongation (mm/day) No. buds/plant Treatment 27 Apr i l (mg l~l> 3-26 Apr i l to 14 May 15-30 May June 12 Cont ro l 1 1.3 1.7 4.6 0.2 SADH 300 0.7 0.B 3.9 0.2 600 1.2 1.3 4.0 0.2 1200 1.0 1.1 3.9 0.1 SADH trend NS NS Cult ivar X SADH L NS Date X SADH NS PP333 75 0.4 0. 1 0.1 1.3 150 0.5 0.1 0. 1 1.9 300 0.4 0.1 0.1 1.9 600 0.5 0.1 0. 1 2.4 1200 0.4 0.0 0.2 2.9 P333 trend L,Q L Cult ivar X PP333 NS L SADH vs. PP333 »•» • #* Date L,D Date X PP333 LL,LQ •Controls for SADH and PP333 were pooled, so contrasts are not orthogonal. NS = not s i g n i f i c a n t , or * • * P < 0.001. L = l inear trend, or 0 = quadratic trend or D = deviation s ign i f icant at P < 0.05. 56 TABLE I I I Effect of SADH end PP333 on vegetati ve attr ibutes of rooted runner cuttings of 'HcFar l in ' and 'Ben Lear' cranberry in Experiment 1 Primary Branches branches per Treatoent per pri eary Shoot dry Root dry Shoot.* rool <mg 1-*) cutting branch wt (ng) Mt (mg) rat io Control 1 5 1 1892 669 2 .9 SADH 300 5 1 1663 549 3.8 600 6 1 2202 662 3.4 1200 6 1 2065 697 3.0 SADH trend NS NS D NS NS Cultivar X SADH NS NS NS NS NS PP333 75 6 2 798 369 2 .3 150 6 2 778 461 l.B 300 6 2 691 325 2. 1 600 6 3 608 324 2 .0 1200 6 2 426 241 1.8 P333 trend NS LQ L,Q L,B L Cultivar X PP333 NS Q NS NS NS SADH vs. PP333 NS « * * *** t i t t * t ' C o n t r o l s fo r SADH and PP333 were p o o l e d , so c o n t r a s t s are not o r t h o g o n a l . NS = not s i g n i f i c a n t , or «#* P < 0 .001 . L = l i n e a r t r e n d , or Q = q u a d r a t i c t rend or D = d e v i a t i o n s i g n i f i c a n t at P < 0 . 0 5 . > 57 TABLE IV Ef f e c t of SADH and PP333 on shoot a t t r i b u t e s and bud set of rooted runner cuttings of 'McFarlin' and 'Ben Lear' cranberry in Experiment 1 Shoot length Leaves Area per Bud per Flower buds (ca) per shoot leaf (c«2) shoot (X) per bud U ) Treataent (ag I" 1) McF1 BL 2 McF BL McF BL McF BL McF BL C o n t r o l 3 27 16 59 33 0.3 0.3 0 1 0 0 SADH 300 22 15 47 31 0.2 0.2 0 0 0 0 600 28 21 64 40 0.3 0.3 0 0 0 0 1200 19 24 48 48 0.3 0.2 4 0 0 0 SADH t r e n d NS SADH v s . PP333 »*« C X SADH v s . PP333 NS NS • «* NS ««« • ** NS C u l t i v a r X SADH L L NS NS NS HcF BL McF BL McF BL McF BL McF BL PP333 75 8 2 36 29 0.2 0.2 2 33 0 3 150 2 1 33 21 0.2 0.2 9 65 0 7 300 2 1 34 23 0.2 0.2 10 53 0 2 600 1 1 25 15 0.2 0.2 19 74 6 3 1200 1 1 20 13 0.2 0.1 55 86 1 4 PP333 trend L,Q L,B L ,e L NS Cult i v a r X PP333 NS NS NS Q NS t NS ' M c F a r l i n 2 B e n L e a r . ' C o n t r o l s f o r SADH and PP333 were p o o l e d , so c o n t r a s t s a r e not o r t h o g o n a l NS = not s i g n i f i c a n t , or * * » P < 0 . 0 0 1 . L = l i n e a r t r e n d , or Q = q u a d r a t i c t r e n d or D = d e v i a t i o n s i g n i f i c a n t at P < 0 . 0 5 . » 5 8 greater i n h i b i t i o n by PP333 of shoot than root growth n has been observed with t r i a l i on apple t rees (Atkinson and C r i s p , 1982). The number of branches on primary branches was increased by PP333, and more for 'Ben Lear ' than ' H c F a r l i n ' . S i m i l a r l y , increased secondary growth due to PP333 was observed with apple t rees (Tukey, 1981). Perhaps t h i s increased branching i s a response to increased l e v e l s of endogenous cy tok in in (Will iams and S t a h l y , 19&8). G A - i n h i b i t o r s can increase endogenous l e v e l s of cy tok in ins in some woody (Skene, 1968) and herbaceous plants (F letcher and Arnold 1986). There was no e f fec t of e i ther PP333 or SADH on the number of primary branches, perhaps because l a t e r a l growth was already st imulated by removal of the shoot apex in s t i k i n g the c u t t i n g . The number of leaves per shoot and area per leaf were s u b s t a n t i a l l y decreased by PP333, but i t appeared that f a c t o r s involved in shoot e longat ion were the most responsive to PP333 (Table IV). These r e s u l t s were s im i la r to those observed on apple seedl ings (Swiet l ik and M i l l e r 1985). Increases in bud set and flower bud set which were n e g l i g i b l e for control and SADH-treated plants were concomitant with the i n h i b i t i o n of shoot e longat ion by PP333. Growth responses s i m i l a r to those r e s u l t i n g from PP333 have been observed for r e l a t i v e l y high rates of SADH on f r u i t t rees (Batjer et a l . , 1964) and highbush blueberry (Shutak, 1968), chlormequat c h l o r i d e (CCC) on pear t rees (Modiibowska, 1965), CCC or phosfon on rhododendron (Stuart , 1961) and ethephon alone or with SADH on young apple t rees (Wi l l iams, 1972). PP333 was observed to induce ear ly bud set in raspberry (Maage , 1986) and 4 to 6 weeks af ter a p p l i c a t i o n in apple , (Lever et a l . , 1983). PP333 has increased the number of flower buds of f r u i t t rees (Tukey, 1981), and rhododendron (Shanks, 1981), 59 Bud set induced by PP333 Mas greater for 'Ben Lear ' than ' H c F a r l i n ' . While Many of the buds set appeared to be of the large Mixed type, d i s s e c t i o n of the buds showed only 1 to 7% contained f lowers (Table IV). Flower buds Mere genera l ly only found at the apices of the older primary shoots from the cu t t ing piece and not from secondary branches. V i s i b l e flower bud formation was not completely synchronous among shoots , and the re fo re , i f a longer per iod had been allowed for development of f l o r a l i n i t i a l s , the flower bud count may have been greater . In commercial cranberry bogs, growth from terminal buds of upr ights begins in ear ly May, and flower induct ion i s thought to begin in l a te June, about 7 to 8 weeks la te r (Roberts and Struckmeyer, 1943; Eaton, 197B). Buds and flower i n i t i a l s are f i r s t observable in ear ly and la te August r e s p e c t i v e l y , approximately 6 to B weeks af ter i n d u c t i o n . Our observat ions on flower bud numbers suggest that some vegetat ive growth and development were required before flower buds were se t . It a lso appears tha t , as in the f i e l d , only some of the e l i g i b l e shoots would develop flower buds. While the exact number of days to flower bud set was not determined in t h i s study, bud formation was observed approximately 15 weeks af ter the i n i t i a t i o n of growth from a x i l l a r y buds of cu t t ing p i e c e s . This was a lso 10 weeks af ter the photoperiod was adjusted to 16-hr, or 7 weeks af ter PP333 a p p l i c a t i o n . B. Experiment 2. 1984 ' H c F a r l i n ' p lants had greater shoot dry weight than 'Ben Lear ' (Table V) . The d i f f e r e n c e s between c u l t i v a r s in shoot length and number in the f i r s t experiment were not observed in the second. E i ther high NPK or peaty s o i l increased the number of shoots , shoot dry weight but not shoot length compared to low NPK or sandy s o i l (Table TABLE V Effect of f t r t i l i z t r r a t i and s o i l type on shoot at tr ibutes and flower bud set of rooted runner cuttings of 'McFar l in ' and 'Ben Lear' cranberry in Experiment 2 Treatment NPK ra te 1 (eg/pot) Total no. shoots Shoot dry wt (ng) Bud set per shoot (X) Flower buds per bud (X) McF2 BL 3 HcF BL McF BL McF BL B 30 17 27 16 23 1498 1234 2938 205B 39 38 67 5B 13 26 4 10 Cul t i var NPK C. X NPK NS #** NS *»» * * « • * • •» NS NS #•» • * * NS Soi l type McF BL McF BL McF BL McF BL Sandy (S) Peaty (P) IB 26 16 23 1722 1161 2714 2131 41 37 62 63 8 14 9 22 Sandy vs. Peaty Cul t ivar X S vs.P NPK X S vs. P • * * NS NS • •# NS NS NS NS NS NS NS NS ^ O N - B ^ P 2 McFar l in NS = not -16.6K. 3Ben Lear, s ign i f icant , or «* P < 0.01, *«« P < 0. 001. L = l inear trend, or Q = quadratic trend or D = deviation s ign i f icant at P < 0.05. 61 V) . ' M c F a r l i n ' appeared more responsive to tht high NPK r a t i and made greater gains in shoot dry weight than 'Ben L e a r ' . While nei ther f e r t i l i z e r rate nor s o i l type had any e f fec t on PP333-induced bud f o r a a t i o n , flower bud set was sharply decreased by high NPK (Tables V and VI) . P a r a d o x i c a l l y , peaty s o i l did not have a s i m i l a r e f f ec t to high NPK on flower bud se t . Increased rates of ni trogen as ammonium s u l f a t e have increased the number of runners , runner length and decreased the number of f lowering upr ights in a young bog over a 5-yr per iod (Eck, 1976). Increased rates of N, P and K a lso increased the number of runners and runner length but only ni trogen as ammonium n i t r a t e decreased y i e l d in a young bog (Eaton, 1971b). Nitrogen appears to have a va r iab le e f fec t on f lowering in other plant species (Kramer and Kozlowski , 1979; Bernier et a l . , 1981). The promotion of bud formation by PP333 was accompanied by a 507. decrease in shoot dry weight (Table VI) . While the promotive e f fec t of high ni trogen rate and peaty s o i l were evident for PP333-treated p l a n t s , the e f f e c t s were great ly decreased. For example, the shoot dry weight for plants treated with the low rates of PP333 and high NPK were s imi la r to contro l values at the low NPK, but PP333-treated plants were very compact with leaves over lapping and reset ted at the ends of the shoots. While leaf number decreased r a p i d l y with increas ing rates of PP333, shoot length appeared to be the vegetat ive a t t r i b u t e most responsive to PP333. Shoot length for PP333-treated plants was decreased to 107. of the shoot length for contro l p lants regard less of NPK rate or s o i l type. The number of shoots per plant in PP333-treated plants was double that of con t ro ls (Table VI I ) . This was l i k e l y due to an increase in branching for primary branches with PP333 as in the f i r s t study. PP333 again increased bud set and flower bud se t . 'Ben Lear ' was again more TABLE VI Effect of PP333 and f e r t i l i z e r rate or to i l - t ype on shoot at tr ibutes and flower bud tet of rooted runner cutt ings of 'HcFar l in ' and 'Ben Lear' cranberry in Experiment 2 PP333 X fertilizer Shoot length Shoot dry Bud set per Flower buds (cm) wt (eg) shoot (%) per bud U) PP333 < tig/pot) Low1 High Low High Low High Low High 0 29 31 2136 4186 17 15 0 0 1.25 3 3 1195 2102 69 63 26 13 2.50 4 3 1104 1933 61 56 30 8 5.00 3 3 1027 1772 65 59 22 8 PP333 trend I.- B,D D,D L ,Q,D L, D,D PP333 X NPK NS L,Q NS Q PP333 X soil PP333 (mg/pot) Sandy Peaty Sandy Peaty Sandy Peaty Sandy Peaty 0 23 36 2276 4046 15 17 0 0 1.25 3 3 1278 2019 67 65 19 20 2.50 4 2 1200 1837 57 59 17 21 5.00 3 3 1011 17B8 66 58 9 22 PP333 X so i l L,Q L ,Q NS NS Cult ivar X PP333 NS NS D D l 8 or 30 mg per pot 20N-8.7P-16.6K. NS = not s ign i f i can t or L = l inear trend, or Q = quadratic trend or D - deviation s ign i f icant at P < 0.05. TABLE VII Ef fect of PP333 on shoot at tr ibutes and bud set of rooted runner cutt ings of 'McFar l in ' and 'Ben Lear' cranberry in Experiment 2 Total no. Leaves Bud set per Flower buds shoots per shoot shoot (X) per bud set (X) PP333 (•g/pot) McF1 BL 2 McF BL McF BL McF BL 0 13 11 42 39 10 21 0 0 1.25 26 22 26 20 45 B7 10 29 2.50 26 25 23 19 4B 68 16 22 5.00 24 22 22 17 52 72 9 22 PP333 L,Q,D L,Q,D L,Q,D L,Q Cult ivar X PP333 NS NS D NS •McFarlin 2Ben Lear. NS = not s ign i f icant or L = l inear trend, or Q = quadratic trend or D = deviation s ign i f i can t at f < 0.05. 64 responsive to PP333 for bud set end flower bud set than ' M c F a r l i n ' . There was some bud set but no flower fo rea t ion by contro l p l a n t s . These vegetat ive buds were observed a f ter supplemental l i g h t i n g was discont inued in Nov. 1984 and nay have resu l ted from short days and tub -opt ina l growing c o n d i t i o n s . Bud set was f i r s t observed about 24 weeks af ter the i n i t i a t i o n of shoot growth, 19 weeks af ter the photoperiod was adjusted to 16 h r , or B weeks af ter treatment with PP333. Bud set in p lants treated with PP333 in t h i s second experiment was s i m i l a r to that obtained in plants treated with PP333 at 1200 mg I"1 in experiment 1. After taking in to account d i f f e rences in method of a p p l i c a t i o n and sand vs . s o i l for a root medium, the amount of PP333 taken up by these plants may have been s i m i l a r . D i f fe rences between these plants in flower bud set might be accounted for by the longer per iod allowed for vegetat ive growth before treatment with PP333; 16 weeks af ter i n i t i a t i o n of shoot growth and 13 weeks af ter the photoperiod was adjusted to 16 hr . That PP333 was appl ied several weeks before the time of year when flower bud induct ion i s thought to occur na tu ra l l y may have in f luenced flower bud format ion. Another p o s s i b l e in f luence may have been the longer period allowed for bud development. (i) Bioassay for PP333 Seed germination of B. napus 'Nestar ' was decreased by PP333 but not by PP333 with 6A 3 (Table VI I I ) . PP333 may prevent seed germination by i n h i b i t i o n of the 6A b iosynthes is required for s t imula t ion o f ^ - a m y l a s e a c t i v i t y (Gilnour and MacMi l lan, 1984). Seedl ing length decreased with increas ing PP333 concentrat ion and was s l i g h t l y increased by the presence of GA 3 . There was no i n t e r a c t i o n between PP333 and BA 3 and t h i s suggests that the 6A 3 rate was inadequate or that PP333 i n h i b i t e d e i ther TABLE VIII Effect of 6A 3 and PP333 on geminat ion and seedling length of B. titpus 'Westar' after 48-hr incubation Germination (X) Seedling length (cm) 6A 3 (mg 1~ » > GA, (mg I"1) PP333 (ag l" 1) 0 50 0 50 0 87 91 2 2 25 44 84 1 1 50 28 86 1 2 100 33 91 1 1 PP333 trend L,D L, Q,D BA, 0 vs. 50 mg 1- 1 * * » «» PP333 X 6A 3 L,Q NS NS = not s i g n i f i c a n t , or »» P < 0.01, ««« P < 0.001. L = l inear t rend, or Q = quadratic trend or D = deviation s ign i f i can t at P < 0.05. 66 g i b b e r e l l i n s or processes involved in e longat ion ( D a l i i e l and Lawrence, 1 9 8 5 ) . Both eean ahoot length and to ta l evapotranspi ra t ion of the seedl ings of B. napus 'Neater ' were i n h i b i t e d in sandy or peaty s o i l s which had been treated with PP333 50 weeks p r io r to the bioassay (Table IX). While the type of s o i l appeared to a f fec t r e s u l t s and i n t e r a c t i o n s were s i g n i f i c a n t , these r e s u l t s appear to be confounded by d i f f e rences in s o i l volume in the cups. A report of s o i l a c t i v i t y of PP333 for at least 1 year (Copas and Wi l l i ams, 19B3) i s cons is tent with the r e s u l t s of the present study. C. Experiment 3. 1985 As in our other experiments above, shoot dry weight was greater for ' M c F a r l i n ' than 'Ben Lear ' (Table X) but no d i f f e r e n c e in shoot length was observed. The number of shoots was greater for ' M c F a r l i n ' than 'Ben L e a r ' . Most of the shoots observed were primary branches from the cut t ing piece and l i t t l e secondary branching was ev ident . Rooted upr ights of 'Ben Lear ' had s l i g h t l y more ber r i es than those of ' M c F a r l i n ' . No d i f f e rences in f lowers per upright and bud set were evident . As in experiment 1 and 2, PP333 decreased the rate of shoot e longa t ion , shoot l eng th , to ta l shoot dry weight and increased bud set (Tables XI, XII, XII I , XIV and XV). Bud formation was observed as ear ly as 7 weeks a f ter i n i t i a t i o n of shoot growth from a x i l l a r y buds, but before PP333 a p p l i c a t i o n . These buds renewed growth q u i c k l y . Formation of new buds, which were apparently dormant, occurred 7 weeks af ter PP333 treatment, or 14 weeks a f ter the i n i t i a t i o n of growth. PP333 i n h i b i t e d shoot e longat ion within 3 weeks of a p p l i c a t i o n and in each subsequent 3 week period (Table XI). GA 3 increased shoot e longat ion 3 weeks af ter a p p l i c a t i o n and in each subsequent 3 week per iod . In the TABLE IX 8. napus 'Wester' , b ioauay of so i l in cranberry experiment 2, 50 weeks after treatment with PP333 Original PP333 treatment (mg/pot) Shoot length (cm) Evapotranspiration (ml) peaty sandy peaty sandy 0 1.25 2.50 5.00 8 6 1 1 1 1 0 1 234 199 196 201 171 149 147 135 Control vs. PP333 Peaty vs. sandy Soi l X PP333 #»# * «*« • •« t * » NS NS « not s i g n i f i c a n t , or * P < 0.05, «« P < 0.01, * « * P < 0.001. 68 TABLE X Shoot at tr ibutes of rooted uprights and runner cutt ings of 'HcFar l in ' and 'Ben Lear' cranberry in Experiment 3 Shoot Total no. length Shoot dry No. No. Bud set per Cul t ivar shoots (cm) wt (ng) flowers berr ies shoot (V.) HcFarlin 5 6 2B9 2 0.3 16 Ben Lear 3 8 240 2 0.5 12 Signi f icance »» NS *«» NS « NS NS = not s i g n i f i c a n t , or « P < 0.05, «* P < 0.01, * « * P < 0.001. TABLE XI Rate of primary shoot elongation for rooted uprights and cutt ings of 'HcFar l in ' and 'Ben Lear' cranberry treated with PP333 and 6A 3 in Experiment 3 PP333 (mg GA, (mg I"1) Rate of shoot elongati on (mm/day) 19 July to B Aug. 9--30 Aug. 31 Aug to 23 • Sept. 0 0 0.8 0.7 0.7 50 0 0.4 0.2 0.1 100 0 0.6 0.2 0. 1 0 50 4.1 1.2 0.6 50 50 1.2 0.6 0.2 100 50 1.9 0.5 0.5 0 100 3. 1 2.0 0.7 50 100 2.6 0.B 0.B 100 100 2.0 1.1 0.4 PP333 trend L,D L,D L,D GA-s trend L,D L L PP333 X BA 3 LD NS NS Cult ivar X PP333 NS NS NS Cult ivar X BA, NS L NS GA, vs AC 94,377 *** NS NS Cult ivar X 6 A 3 vs. AC 94,377 NS L NS NS = not s i g n i f i c a n t , or «*« P < 0.001. L = l inear trend or D = deviation s ign i f icant at f < 0.05. TABLE XII Shoot at t r ibutes and bud set of rooted uprights and runner cutt ings oi 'McFar l in ' and 'Ben Lear ' cranberry treated with PP333 and GA3 in Experiment 3. Shoot Shoot Bud set PP333 6A 3 Total length dry wt per shoot (tig l" 1) (mg l~ l) no. shoots (cm) (mg) (X) 0 0 5 B 349 9 50 0 6 3 279 43 100 0 4 4 255 29 0 50 4 16 379 3 50 50 4 7 262 1 100 50 4 11 230 0 0 100 4 17 335 0 50 100 4 13 284 6 100 100 4 12 274 1 PP333 trend NS L,D L,D L,D GA3 trend L L,D NS L PP333 X GA3 DL DD NS NS Cult ivar (C) X PP333 NS NS NS NS Cult ivar X 6 A 3 NS NS NS NS BA 3 vs AC 94,377 NS *#« NS NS C X GA3 vs. AC 94,3772 NS NS NS NS NS = not s i g n i f i c a n t , or «»* P < 0.001. L = l inear trend or D = deviation s ign i f icant at P < 0.' TABLE XIII Rati of primary shoot i longat ion for rooted uprights and cutt ings of 'McFar l in ' and 'Ben Lear' cranberry treated PP333 and AC 94,377 in Experiment 3 Rate of shoot elongation (mm/day) PP333 AC 943477 19 July 31 Aug. (mg l" l> (mg 1-') to 8 Aug. 9-30 Aug. to 23 Sept. 0 0 1.4 1.5 0.7 50 0 0.7 0.3 0.1 100 0 0.5 0.2 0. 1 0 50 2.5 2. 1 1.3 50 50 1.1 0.5 0.1 100 50 1.2 0.4 0.1 0 100 1.9 1.0 0.3 50 100 1.2 0.7 0.4 100 100 1.2 0.2 0.2 AC 94,377 trend L,D NS NS Cul t i var X AC 94,377 NS D NS PP333 X AC 94,377 DD NS LD NS <* not s i g n i f i c a n t . L = l inear trend, or D e deviation s ign i f icant at P < 0.05. TABLE XIV Shoot at tr ibutes and bud set of rooted uprights and runner cutt ings of 'HcFar l in ' and 'Ben Lear' cranberry treated with PP333 and AC 94,377 in Experiment 3 Total Shoot Shoot Bud set PP333 AC 94,377 no. 1ength dry Kt per (mg l - » ) (ng l" 1) •hoots (cn) (ng) •hoot (X) 0 0 4 9 355 4 50 0 5 4 255 42 100 0 5 3 232 36 0 50 4 IB 332 0 50 50 4 7 272 IB 100 50 5 5 306 11 0 100 4 10 356 0 50 100 4 8 281 6 100 100 4 7 280 8 AC 94,377 trend NS L,D NS L PP333 X AC 94,377 NS LD NS NS Cul t i var X AC 94,377 NS D NS NS NS = not s i g n i f i c a n t . L = l inear t rend, or Q = quadratic trend or D = deviation s ign i f icant at P < 0.05. TABLE XV Shoot a t t r ibute* and bud let of rooted upright! and runner cutt ings of 'McFar l in ' and 'Ben Lear' cranberry treated with PP333 and NAA in Experiment 3 Total Shoot Shoot Bud set PP333 NAA no. length dry wt per (mg 1-M (mg shoots (cm) (eg) shoot (X) 0 0 5 8 412 6 50 0 5 4 235 33 100 0 4 3 174 26 0 50 4 5 215 3 50 50 4 3 143 9 100 50 4 3 120 15 0 100 4 4 167 2 50 100 3 4 126 2 100 100 4 4 150 17 NAA trend NS NS L,D L PP333 X NAA NS LL LL NS NS = not s i g n i f i c a n t . L = l inear trend, or Q 5 quadratic trend or D = deviation s ign i f icant at P < 0.05. 74 • f i rst p e r i o d , BA 3 at 50 ng 1 ~ 1 Mas the most e f f e c t i v e at increas ing shoot e longat ion of p lants i f they Mere not t reated K i t h PP333. 6A 3 at 100 mg 1 _ 1 Mas the most e f f e c t i v e at i nc reas ing shoot e longat ion for p lants t reated with PP333. Genera l l y , the response of plant growth to 6A 3 was in several ways opposite to the response to PP333 (Table XII) . 6A 3 decreased the number of shoots and bud set and increased shoot length but un l ike P333 had no e f fec t on shoot dry weight. The e f f e c t s of combined PP333 and 6A 3 on shoot length and bud set were s i m i l a r to the e f f e c t s of GA 3 a lone , but a small e f fec t of PP333 was s t i l l ev ident . In c o n t r a s t , the e f fec t of PP333 plus 6A 3 on shoot dry weight was s i m i l a r to the e f fec t of PP333 alone. These r e s u l t s support the suggestions that the e f fec t of PP333 on plant growth i s not simply due to i n h i b i t i o n of GA 3 b iosynthes is (Dalz ie l and Lawrence, 19B5; Wang and S t e f f e n s , 19B5). AC 94,377 exhib i ted some growth regulator proper t ies s i m i l a r to G A 3 , but the response of the p lants to GA 3 was genera l ly greater than the response to AC 94,377 at equal concentrat ions (Table XII and XIV). S imi lar f ind ings have been observed for AC 94,377 in a number of 6A bioassays (Sut t le and Schre iner , 19B2). AC 94,377 increased the rate of shoot e longat ion and, as with 6 A 3 , t h i s e f fec t decreased with time (Table XII I ) . AC 94,377 had no e f fec t on the number of shoots or shoot dry weight, but increased shoot length and decreased bud set (Table XIV). The e f f e c t s of PP333 plus AC 94,377 on shoot length and bud set were s i m i l a r to the e f f e c t s of AC 94,377 alone but a small e f f ec t from PP333 was s t i l l ev ident . In c o n t r a s t , the e f fec t of PP333 plus AC 94,377 on shoot dry weight was s i m i l a r to the e f fec t of PP333 alone. AC 94,377 was reported to st imulate shoot e longat ion of l e t tuce hypocotyls in the presence of AMD-161B and CCC (Sutt le and Schre iner , 19B2). 75 Shoot growth was poor at a resu l t of treatments with NAA and the rates used appeared to be excessive (Doughty, 1962). NAA had no e f fec t on the number of shoots but decreased shoot l eng th , to ta l shoot dry weight, end bud set (Table XV). PP333 plus NAA decreased shoot length and shoot length and shoot dry weight more than i f e i ther was appl ied alone. This suggests the two substances decreased growth by d i f f e r e n t mechanisms. A b s c i s i c ac id had no v i s i b l e e f fec t on shoot growth or bud set and did not in te rac t with PP333, therefore the r e s u l t s are not presented (Appendix Table A . I I I ) . Nhi le some r e s u l t s i n d i c a t e that continuous exposure to ABA may have been more e f f e c t i v e in inducing bud formation compared to per iod ic sprays , r e s u l t s with ABA on woody plants are often v a r i a b l e . This i s poss ib ly due to poor penetrat ion or rapid metabolism (Nooden and Weber, 197B). > , 76 CHAPTER 6 CRANBERRY YIELD RESPONSE TO NITROSEN AND PACLOBUTRAZOL INTRODUCTION Runnering in the cranberry ie responsive to ni trogen f e r t i l i z a t i o n and there i s a narrow range between d e f i c i e n c y and overst imulat ion (Addoots and Hounce 1932, Tor io and Eck 1969). This range may vary with environmental condi t ions and age of the bog (Dana 196Ba, 1968b). Hence, problems with overcrowding and with harvest operat ions caused by excessive runnering are common. Nitrogen f e r t i l i z a t i o n i s necessary for maintaining the plant canopy and c ropp ing , but besides i t s e f fec t on runner ing, o v e r - a p p l i c a t i o n a lso can decrease f r u i t qua l i t y and in the year a f ter a p p l i c a t i o n i t can decrease the number of f lowering upr ights and y i e l d (Eaton, 1971a; Eck, 1976). Mineral nut r ients may in f luence some aspects of plant growth by a l t e r i n g the l e v e l s or r a t i o s of endogenous plant growth substances (Woolley and Nareing, 1972; Rajagopal and Rao 1974; Horgan and Nareing, 1980; Dar ra l l and Nareing, 1981). S i b b e r e l l i n s (6A) or GA- l i ke substances are impl icated as promotors of shoot growth in cranberry (Eady and Eaton, 1972) and the i r concentrat ions may be in f luenced by plant ni t rogen concentrat ions (Krauss and Marschner, 1976). Appl ied 6A 3 t increases f r u i t s e t , runner and upright e longat ion and decreases bud set (Devlin and Demoranvil le 1967; Mainland and Eck, 1968). Flowering and y i e l d are decreased in the fo l lowing year as a consequence. Growth retardants such as chlormequat, SADH, and PP333 which decrease g i b b e r e l l i n b iosynthes is of p lants (Dicks, 19B0; Hedden and Sraebe, 1985) can decrease vegetat ive growth and increase flower bud set 77 of woody plants (Stuar t , 1961; Shutak, 1968; Shanks, 1981). These types of compounds may be an e f f e c t i v e Means for contro l of vegetat ive growth and f lowering for cranberry . A SADH spray of 2500 eg 1~*, appl ied 2 weeks af ter bloom on cranberry decreased winter in jury (Doughty and Sheer, 1969), and 2 sprays of SADH at 1500 mg I - 1 at f u l l bloom increased lower bud set without any s i g n i f i c a n t e f fec t on y i e l d (Lenhardt and Eaton, 1976). SADH appears to have some potent ia l for decreasing a l te rnate bearing (Lenhardt and Eaton, 1976). A l ternate bearing for the cranberry has been suggested, as non-f lowering uprights were observed to set more flower buds than f lowering upr ights (Lenhardt and Eaton, 1976) and the y i e l d components, f lowers per leaf number and f r u i t s e t , were negat ive ly cor re la ted to the number of flower buds (Eaton et a l . , 1983). In a glasshouse study, flower buds were formed for plants t reated with f o l i a r sprays of PP333 with rates as low as 75 mg l ~ l while no buds were set for p lants t reated with SADH at 1200 mg 1~* (HcArthur and Eaton, 1987b or Chapter 5) . Thus, low rates of f o l i a r - a p p l i e d PP333 may be more e f f e c t i v e than SADH as an a l t e r n a t i v e to pruning for control of runnering in cranberry and may benef i t y i e l d by decreasing a l ternate bear ing. Sequential y i e l d component ana lys is (SYCA) has been used in cranberry to i d e n t i f y important y i e l d components and the i r cont r ibu t ion to y i e l d v a r i a t i o n (Eaton and Kyte, 1978; Eaton and MacPherson, 1978; Shawa et a l . , 1981). Recent ly , the use of SYCA was expanded by incorpora t ing ana lys is of var iance (ANOVA) in to SYCA to assess treatment e f f e c t s on the orthogonal y i e l d components (Eaton et a l . , 1986). C u l t i v a r d i f f e rences in y i e l d for ind iv idua l upr ights have been re la ted to d i f f e r e n c e s in orthogonal or adjusted components by t h i s method of two-dimensional p a r t i t i o n i n g (TDP) (Baumann and Eaton, 1986). The present study was undertaken to determine the vegetat ive and y i e l d 78 response of cranberry to PP333 in the f i e l d . Nitrogen f e r t i l i z a t i o n Mas var ied to determine i f i t Mould increase runnering and to see i f t h i s e f f e c t Mould bemodified by PP333. TDP Mas used to Measure the c o n t r i b u t i o n of each y i e l d component to y i e l d , and assess treatment e f f e c t s upon these c o n t r i b u t i o n s . MATERIALS AND METHODS A. F i e l d Experiments Treatments consis ted of a l l 6 combinations of 2 l e v e l s of ni trogen and 3 l e v e l s of PP333 randomly arranged in each of 4 complete b locks . This experiment Mas conducted in 1984 in each of a commercial bog of ' H c F a r l i n ' or 'Bergman'. F e r t i l i z e r <4.8N-17P-17.2K) Mas appl ied on 5 May 1984 at 146 or 179 kg h a - 1 to the ' M c F a r l i n ' or 'Bergman' bog r e s p e c t i v e l y . The d i f f e r e n t f e r t i l i z e r rates of NPK appl ied confounds c u l t i v a r d i f f e rences with loca t ion and f e r t i l i z e r r a t e s . Both bogs received supplemental Mg, S, B and Cu during the summer of 1984. Both bogs Mere Met harvested. On 5 June 1984, a 9 m X 14 a area that Mas r e l a t i v e l y f ree of weeds and with a uniform upright densi ty was chosen in each bog. Twenty-four 1-m2 p lo ts with 1 m between each adjacent plot were marked out in both bogs and 5 f lowering upr ights per plot were tagged for i n d i v i d u a l shoot and y i e l d measurements. On 26 June 1984, randomly-assigned p l o t s rece ived granular n i t rogen (34-0-0) (as ammonium n i t ra te ) at a rate of 60 kg h a - 1 (6 g m - 2 ) . On 26 June 1984 ( fu l l -b loom) and again on 10 July 1984, PP333 was appl ied at 0, 75, 150 mg l " 1 a . i . in 0.1% Tween'20 as a shoot spray to run-of f (500 ml s r 2 ) . PP333 was obtained as a 25% a . i . suspension ( ICI -Americas) . 79 On 2 Oct. 1984, tagged upr ights Mere c o l l e c t e d , frozen end stored for several Months. Length, leaf number, leaf a rea , shoot dry Height, terminal bud type, flower nueber, to ta l seed number and to ta l f r u i t f resh Height for current season's growth of each upright were determined. On 4 Oct. 1984, a sample of a l l shoots and f r u i t was c o l l e c t e d from within a 4 dm2 quadrat randomly placed in each p l o t . The number of runners o r i g i n a t i n g in the current year wi thin the sample area was determined. Uprights were sorted in to 4 ca tegor ies : Uv«, U « v , U««, by the i r f lowering status in the current and the previous year. New upr ights were included in the category U w The to ta l number of f lowers for each shoot type, to ta l number of f r u i t s and to ta l f r u i t f resh weight per sample were determined. A subsample of 10 upr ights from each shoot type was used to estimate bud set and flower bud set within p l o t s . Large plump buds were rated as flower buds while small buds were considered as vegeta t ive . Dn 7 May 1985, 5 randomly-selected upr ights with terminal buds were tagged in each plot of the 'Bergman' bog. Per iod ic growth and y i e l d measurements were made for i n d i v i d u a l shoots u n t i l l a te July 1985. On 4 Oct. 1985, shoots and the i r f r u i t were c o l l e c t e d and measured as in 1984. B. S t a t i s t i c a l methods Ana lys is of var iance with i n d i v i d u a l degree of freedom tes ts was used to determine d i f f e rences between c u l t i v a r s , shoot types, and the e f f e c t s of ni t rogen and PP333 on vegetat ive and y i e l d a t t r i b u t e s . Number of upr ights (U), number of f lowering upr ights ( U « ) , number of f lowers (F ) , number of f r u i t s (B) and to ta l f r u i t f resh weight (Y) from the 4 dm2 samples were used to compute the r a t i o s U (upright densi ty per dm 2 ) , U*/U (proport ion of upr ights which f lowered) , f/U< (f lowers per f lowering u p r i g h t ) , B/F ( f r u i t s e t ) , Y/B ( f r u i t s ize) and Y (y ie ld per dm 2 ) . 80 References in t h i text to bud l i t and flower bud set re fer to percentage of upr ights with a terminal bud and percentage of those buds that were f l o r a l r e s p e c t i v e l y . Treatment e f f e c t s for the unadjusted r a t i o s were f i r s t examined with ANOVA, then the natural logarithms of the r a t i o s were computed and the r e s u l t s analyzed with TDP which combines mul t ip le regress ion with ANOVA (Eaton et a l . , 1966). Each va r iab le cont r ibu t ing to y i e l d for the add i t i ve model! log (U) + log (UWU) + log (F/U*> + log (B/F) + log (Y/B)= log (Y/dm 2) was orthogonal ized (Winer, 1971) with success ive va r iab les being r e c a l c u l a t e d as r e s i d u a l s from mul t ip le regress ions upon e a r l i e r independent v a r i a b l e s (Eaton and Kyte, 197B). Y i e l d was then regressed upon these adjusted y i e l d components. The R 2 for each of these adjusted y i e l d components corresponds to i t s incremental cont r ibu t ion to y i e l d v a r i a t i o n in the regress ion model and r e f l e c t s i t s independent e f fec t on y i e l d v a r i a t i o n as i t developed. Treatment and error sources of v a r i a t i o n for each orthogonal independent y i e l d component were p a r t i t i o n e d by ANOVA. The r e s u l t s of ANOVA were then used to a l l o c a t e R 2 proport i onal1y. RESULTS AND DISCUSSION A. 1984 - Indiv idual f lowering upr iohts Vegetat ive growth and bud set for f lowering upr ights were greater in ' M c F a r l i n ' than in 'Bergman', even though the l a t t e r bog received more f e r t i l i z e r (Table I). A previous study ind ica ted ' M c F a r l i n ' tends to be more responsive to f e r t i l i z a t i o n than some c u l t i v a r s and t h i s poss ib ly expla ins c u l t i v a r d i f f e rences here (McArthur end Eaton, 1987b or 81 TABLE I Shoot attribute 's end bud set in 1984 for flowering uprights of 'HcFarl in' and 'Bergman' cranberry treated with nitrogen and PP333 Shoot Leaves Area per Shoot dry Buds per Flower buds length (cn) per shoot leaf (ca 2) wt (g> shoot (X) per bud (X) PP333 (ag l -« ) McF eg 2 McF Bg McF Bg McF Bg McF Bg McF Bg 0 e 6 37 33 0.20 0.13 0.16 0.11 43 8 5 5 75 B 7 36 32 0.18 0.13 0.16 0.13 83 55 3B 38 150 8 8 37 33 0.19 0.14 0.17 0.13 83 70 58 55 Cultivar (C> • t * » * te* • #* »«* NS PP333 trend NS NS D L L,D L C X PP333 L,D NS D D NS NS Nitrogen (N) NS NS NS NS NS NS N X PP333 NS NS NS NS NS NS 'HcFarlin 'Bergman. NS = Not s igni f icant , or « P < 0. 05, *» P < 0. 01 and «•« P < 0. 001. L « Linear trend or D » deviation signif icant at P < 0 .05 . 82 Chapter 5 ) , No c u l t i v a r d i f f e rence for flower bud tet was observed. Nitrogen had l i t t l e e f fec t on any of the f i n a l shoot measurements, bud set or y i e l d in 1984 or 1985. A l o c a l i z e d N e f f e c t to se lec ted p lo ts would probably have required a f o l i a r a p p l i c a t i o n of N, consider ing the t r a i l i n g nature of the runners within the bog canopy. S imi lar to observat ions on apple (Tukey, 1981) and rhododendron (Shanks 1981), PP333 increased bud set and flower bud set on upr ights for both c u l t i v a r s (Table I) . PP333 did not i n h i b i t upright growth or increase branching as in an e a r l i e r study (HcArthur and Eaton,1987b or Chapter 5 ) , poss ib ly because i t was appl ied la te in the f lowering stage and a f ter f r u i t set when the most rapid phase of upright growth had passed. Some s i g n i f i c a n t i n t e r a c t i o n s between PP333 and c u l t i v a r suggest shoot growth was s l i g h t l y promoted for 'Bergman' but not ' H c F a r l i n ' , although t h i s seems u n l i k e l y . Both c u l t i v a r s were s i m i l a r in the i r y i e l d a t t r i b u t e s for ind iv idua l f lowering upr ights in 1984. Bergman had more seeds per f r u i t (S/B) than ' H c F a r l i n ' (Table I I) . Others have a lso reported number of seeds per f r u i t as greater for 'Bergman' than ' H c F a r l i n ' (Baumann and Eaton, 1986), but i t i s not poss ib le to separate genetic and environmental in f luences in f i e l d s tudies when l o c a t i o n and management systems are confounded with c u l t i v a r e f f e c t s . The number of f lowers was unaffected by PP333, probably s ince flower induct ion would have occurred during the previous season (Table* II). PP333 decreased f r u i t set ( B / F ) , f r u i t s i ze (Y /B) , f r u i t enlargement (Y/S) and y i e l d per upright (Y / IM in 1984. S imi la r e f f e c t s were observed for f r u i t set and y i e l d of plum (Webster and Quin lan , 1984). Decreased f r u i t s i z e was observed as a r e s u l t of PP333 on apple (Tukey, 1981). However, these r e s u l t s are contrary to those reported for 83 TABLE II F l o o r i n g and frui t ing attr ibute! in 1964 for flowering upright! of 'McFarlin' and 'Bergman' cranberry treated with nitrogen and PP333 F/UV B/F Y/B (g) S/B ' Y/S <g> Y/U,<g) PP333 (mg I"1) McF2 Bg 3 McF Bg McF Bg McF Bg McF Bg McF Bg 0 5 4 0.53 0.52 1.1 1.1 13 15 0. 09 0.07 2.6 2.4 75 4 5 0.45 0.40 0.6 0.6 13 15 0. 05 0.05 1.3 1.1 150 5 4 0.39 0.43 0.5 0.7 13 15 0. 04 0.05 1.0 1.2 Cultivar <C> NS NS NS f NS NS PP333 trend NS L L,D NS L,D t -.D C X PP333 NS NS L NS L NS Nitrogen (N) NS NS NS NS NS NS N X PP333 NS D NS NS NS NS ' u \ * number of flowering uprights; F • number of flowers; B • number of f ru i ts ; S = number of seeds; Y = total f rui t fresh weight. 2McFarlin 'Bergman. NS = Not s igni f icant , or « P < 0.05, «» P < 0.01 and ««* P < 0.001. L = Linear trend or D = deviation signif icant «t P < 0.05. 84 strawberry (McArthur end Eaton, 19B7* or Chapter 3) where PP333 appl ied at f u l l bloom did not in f luence f r u i t se t . PP333 had no e f fec t on seeds per f r u i t (S/B) for f r u i t s that did s e t . Seed enlargement (Y/S) for ' H c F a r l i n ' was decreased more by PP333 than for 'Bergman', and t h i s appeared to account for a s i m i l a r d i f f e rence in f r u i t s i z e (Y/B). G i b b e r e l l i c ac id st imulates some f r u i t development in cranberry (Devlin and Demoranvi11e, 1967) and GA b iosynthes is in po l len during germination and in developing seeds are important for s t imula t ion of f r u i t growth and continued development (Goodwin, 197B). The decrease in f r u i t set by PP333 in the present study may have been due to a decrease in GA b iosynthes is at e i ther stage. PP333 decreased po l len germination in strawberry (McArthur and Eaton, 19B7a or Chapter 3) and a s i m i l a r e f f ec t in cranberry may be p o s s i b l e . The fact that some f r u i t set took place may r e f l e c t the normal v a r i a t i o n in the t iming of flower opening between i n d i v i d u a l cranberry u p r i g h t s , and i n d i v i d u a l f lowers on an upr igh t , or v a r i a t i o n in the amount of PP333 de l ivered to ind iv idua l f lowers . B. 19B5 - Indiv idual shoots The terminal buds from upr ights that were tagged in May 1985, did not a l l become f lowering upr igh ts . Shoot types were 57. runners, 11% non-f lowering upr ights (3% U w , B'/. U v « ) , and 65% f lowering upr ights (5BV. U « v , 27X U « « ) . Inc lusion of runners and non-f lowering upr ights appeared to r e s u l t in an overest imat ion for some vegetat ive a t t r i b u t e s and a s l i g h t underestimation for some y i e l d a t t r i b u t e s compared to to the r e s u l t s in 1984. In 1985, the rate of e longat ion for 'Bergman' shoots decreased uniformly from mid May u n t i l l a te July (Table I I I ) . PP333 appl ied in TABLE III Rate of shoot 1 elongation in 19B5 for 'Bergnan' cranberry 1984 Rate of ihoot elongation (an/day) in 1985 PP333 12 to 19 May 2 to 16 to 30 Jun.to 14 to <mg l - M 18 May to 1 Jun. 15 June 29 June 13 July 20 July 0 2. 1 1.9 1.6 1.2 0.9 1. 1 75 2.1 1.7 1.1 0.7 0.4 0.1 150 1.6 1.7 1.0 0.5 0.2 0.0 PP333 trend L Ni trogen NS Nitrogen X PP333 NS Date L Date X PP333 L Date X nitrogen NS 'Shoot types M e r e 5% runners, 3X U w , 8% U v , , 58"/. U , v , 272 Upright (U,j) c l a s s i f i e d by i « current flowering status ( v = non-flowering or • = flowering) and j = flowering status previous season. NS * Not s i g n i f i c a n t , or L = Linear trend s igni f icant at f ( 0.05. 8 6 1984 decreased the r t t e of e longat ion in 1985, with the i n h i b i t o r y e f fec t increas ing over the per iod of t h i s study. F ina l shoot length , area per l e a f , and shoot dry weight of the tagged shoots in 1985 were a lso decreased'by PP333 (Table IV). The number of l eaves , nueber of branches, and bud set were not s i g n i f i c a n t l y a f fec ted by the treatments in the previous year. The r e s u l t s on runner branching discussed l a te r and a previous study (McArthur and Eaton, 1987b or Chapter 5) ind ica te an increase in branching occurs when PP333 i s appl ied during the period of shoot e longat ion . Uprights t reated with PP333 in 1984 had a higher number of f lowers in 1985, poss ib ly as i t was appl ied at about the time of flower induct ion (Table V) (Lenhardt and Eaton, 1976; Eaton, 1978). Other y i e l d a t t r i b u t e s were not a f fec ted . These observat ions on growth and f lowering in 1985 suggest PP333 had an e f fec t on bud growth the previous summer and that the decreased shoot growth observed was not due to PP333 res idues . In a woody perennial p l a n t , e f f e c t s that p e r s i s t in to the fo l lowing year are not n e c e s s a r i l y the same as (or due to) ac t ive chemical s o i l res idues which are detectable by b ioassay. This cranberry bog was f looded for several weeks during harvest in 1964 and t h i s may have dispersed any r e s i d u e s . C. Unadjusted y i e l d components Upright densi ty (U) was s i m i l a r for c u l t i v a r s . ' H c F a r l i n ' had a higher proport ion of upr ights f lowering <U*/U) compared to 'Bergman' (Table VI) . 'Bergman' had more f lowers per f lowering upright ( F / U « > , f r u i t set (B/F) and f r u i t s i z e (Y/B) than ' H c F a r l i n ' . No c u l t i v a r d i f f e r e n c e was observed for f i n a l y i e l d . PP333 had no e f fec t on U, U*/U or F /U* as might be expected for 87 TABLE IV 6hoot' a t t r ibute ! and bud aet in 1785 for 'Bergman' cranberry bog 19B4 Treatmenti Shoot Leaves Area Shoot Buds Flower PP333 length per per leaf dry No. per buds per (mg l-»> (cm) shoot (cm2) wt (g) branches shootm bud ('/.) 0 12 43 0.15 0. IB 0.2 38 8 75 7 40 0. 13 0.13 0.4 35 5 150 6 36 0.11 0.11 0.4 40 3 PP333 trend L NS L L NS NS NS Ni trogen NS NS NS NS NS NS NS Nitrogen X PP333 NS NS D NS NS NS D 'Shoot types were 5X runners, 3X l l „ , 87. U v « , 5BX U f v, 27X U f « . Upright (U 4 J ) c l a s s i f i e d by i = current flowering status ( v = non-flowering or f = flowering) and j = flowering status previous season. NS = Not s i g n i f i c a n t , or L = l inear trend or D = deviation s igni f icant at P < 0.05. TABLE V Flowering and f ru i t ing attributes in 1985 for 'Bergman' cranberry 1 PP333 (eg l" 1) F / U * 2 B/F V/B (g) S/B Y/S <g> Y/U* (g) 0 3.1 0.39 0.9 14 0.05 l .B 75 3.9 0.44 1.0 13 0.08 2.0 150 4.9 0.37 1.0 15 0.07 2.1 PP333 trend L NS NS NS NS NS Ni trogen NS NS NS NS NS NS Nitrogen X PP333 NS NS NS NS NS NS 'Shoot types were 5X i r u n n e r B , 3X Uv„, B% U 56'/. U,v, 27X U,,. Upright <Uu> c l a s s i f i e d by , • current flowering status ( v B non-flowering i Dr f c flowering) and j = flowering status previ ous season. 2U< * number of flowering uprights; F = number of flowers; 8 = number of f ru i ts ; S « number of seeds; Y = total f ru i t fresh weight. NS ° not s i g n i f i c a n t , L = l inear trend s igni f icant at P < 0.05. TABLE VI Geometric means of y1•1d components ior 'McFarl in ' and 'Bergman' cranberry Cult ivar U l F/u , B/F Y/B (g) Y (g) McFar1i n Bergman 59 62 0.41 0.27 3.1 0.26 3.3 0.31 0.76 0.94 15.4 16.5 Signif icance NS »»» ft* • ft NS 'U = no. of uprights per dm2 area, u\ • no. of flowering uprights, F » no. of f lowers, B B no. of f r u i t s , Y * total f ru i t fresh weight per dm2 area. NS = Not s i g n i f i c a n t , or # P < 0.05, *# P < 0.01 and * » * P < 0.001. 90 these components Mere l a r g e l y determined by fac tors during the previous season and PP333 was appl ied during and soon af ter f lowering (Table VI I ) . S imi la r to the r e s u l t s for i n d i v i d u a l tagged u p r i g h t s , PP333 great ly decreased f r u i t set ( B / F ) , f r u i t s i z e (Y/B) and y i e l d (Y/dm 3 ) . D. Adjusted y i e l d components No d i f f e r e n c e s in y i e l d for c u l t i v a r s or nitrogen rate were observed, however, y i e l d was af fected s u b s t a n t i a l l y by PP333 (Table VI I I ) . The largest cont r ibutor to y i e l d v a r i a t i o n in the regression model was the adjusted f r u i t set (66.2*/.), fol lowed by the adjusted f r u i t s i z e (17.AX) and the adjusted number of f lowers per f lowering upright (9.4X). F r u i t set has been i d e n t i f i e d often as a major source of y i e l d v a r i a t i o n (Eaton and Kyte, 1978; Shawa et a l . , 1981). Upright densi ty and the proport ion of upr ights f lowering made minor con t r ibu t ions suggesting the areas sampled were qui te uniform for these components. By two-dimensional p a r t i t i o n i n g of sum of squares for bog y i e l d , c u l t i v a r d i f f e rences for the adjusted number of f lowers per f lowering upright (F/Uf) made a s i g n i f i c a n t cont r ibu t ion (1.3X) to y i e l d v a r i a t i o n (Table VII I ) . The adjusted proport ion of upr ights f lowering (Uf/U> made a s i g n i f i c a n t cont r ibu t ion (1.4X), s im i l a r to flowers per f lowering upr ight . The negative value for cross-products of c u l t i v a r s (-2.8X) cance l led out any e f f e c t s of e a r l i e r components. Thus i t appeared that while ' H c F a r l i n ' had a higher proport ion of upr ights f lower ing , 'Bergman' had more f lowers per upright f lowering (Table IX) and there was no net d i f f e r e n c e in y i e l d for c u l t i v a r s . This may be an example of c u l t i v a r y i e l d component compensation (Adams, 1967), however, s ince the two bogs received s l i g h t l y d i f f e r e n t ra tes of f e r t i l i z e r , i t a lso i s poss ib le that the extra f e r t i l i z e r in the 'Bergman' bog favoured better flower and TABLE VII Effect of PP333 and nitrogen on geometric means of y ie ld components 'HcFarl in'and 'Bergman' cranberry PP333 (mg l->) U 1 U«/U F/U, B/F Y/B (g) Y (g) 0 57 0.33 3.3 0.47 1. 05 29.9 75 63 0.33 3.2 0.20 0. 77 B.9 150 61 0.35 3.2 0.20 0. 74 9.0 PP333 trend NS NS NS L,D L L,D Cult ivar X PP333 NS N5 NS NS NS NS Nitrogen X PP333 NS NS NS NS NS NS l U e no. of uprights per dm2 area, U« » no. of flowering uprights, F = no. of flowers, B * no. of f r u i t s , Y • total f ru i t fresh weight per dm2 area. NS « Not s ign i f i can t , or L • l inear trend or D = deviation s igni f icant at P < 0.5. TABLE VIII Yield variation in 'McFarl in ' and 'Bergman' cranberry expressed ae incremental contributions to R 2 with treatment effects partit ioned by ANOVA Adjusted y ie ld components1 Source of variation df U 2 u,/u F/U, B/F Y/B XX InY Cultivar (C) 1 0 1#»* 1»* 0 0 -3 0 Block within C 6 1 0 2 3 2 -2 6 Nitrogen (N) 1 0 0 0 0 1 -2 0 PP333 l inear (L) i 0 0 0 29*** 2* 18 48*** PP333 deviation <D) 1 0 0 0 l i t * * 0 5 16*** N X L 1 0 0 0 0 1 -1 0 N X D 1 0 0 0 0 0 0 0 C X N 1 0 0 0 0 0 -1 0 C X L 1 0 0 0 0 0 -1 0 C X D 1 0 0 0 0 0 0 0 C X N X P 2 0 0 1» 2 1 -4 I Experimental error 30 2 1 5 19 11 -11 28 Total U) 47 4 3 9* 66***18*** 0 100 •The a d j u s t e d y i e l d components are the l o g - t r a n s f o r m e d , o r t h o g o n a l i r e d and s c a l e d y i e l d components. The t o t a l sum of squares fo r InY was 25.4 2 U = no. u p r i g h t s per dm 2 a r e a , LW = no. f l o w e r i n g u p r i g h t s , F = no. f l o w e r s B = no. f r u i t s , Y = t o t a l f r u i t f r e s h weight per dm 3 , XX = v a r i a t i o n due to c r o s s p roduc ts between ad jus ted y i e l d components * P < 0.05, * * P < 0.01 and * * * P < 0.001. S i g n i f i c a n c e in the t reatment row r e f e r s to ANOVA and in the t o t a l row r e f e r s to r e g r e s s i o n a n a l y s i s . 93 TABLE IX Meant of adjusted y ie ld components' of 'HcFar l in ' and 'Bergman' cranberry Cult ivar U 2 U*/U F/U* B/F Y/B InY HcFarlin 4.1 0.21 -0.034 -0.0057-0.034 2.5 Bergman 4.1 -0.21 0.034 0.0057 0.034 2.5 Signif icance NS •« NS NS NS 'The means of the adjusted yie ld components are residuals from regression using logarithm.-transformed yield components. 2 U = no. uprights per dm2 areat 1) « no. uprights, LU * no. flowering uprights, F • no. flowers, B = no. f r u i t s , Y • total f ru i t fresh weight per dm2. NS = Not s ign i f i can t , « P < 0.05, •» P < 0.01 and * * * P < 0.001. 94 f r u i t development. The i n h i b i t o r y e f fec t of PP333 on f r u i t set (B/F) accounted for a substant ia l amount of t o t a l y i e l d v a r i a t i o n (29% and 11%) (Tables VIII and X). PP333 a lso decreased f r u i t s i z e (Y/B) and t h i s eade a small but s i g n i f i c a n t con t r ibu t ion to y i e l d v a r i a t i o n af ter taking in to account e a r l i e r y i e l d components. The e f fec t of PP333 on f r u i t s i z e (Y/B) may be re la ted to the observed e f fec t of PP333 on f r u i t enlargement (Y/S) (Table I I) . Large p o s i t i v e values (17.6% and 5.3%) for the cross-products for RP333 trends ind ica te PP333 decreased both f r u i t set (B/F) and f r u i t s i ze (Y/B) in a s i m i l a r fashion (Table VI I I ) . This was poss ib ly through the i n h i b i t i o n of GA b i o s y n t h e s i s . PP333 has been reported to a f fec t other aspects of plant growth and metabolism besides GA b iosynthes is (Da lz ie l and Lawrence, 19B5, Wang and S t e f f e n s , 1985). These other processes may have a ro le in f r u i t set and f r u i t s i z e . That there was a small but s i g n i f i c a n t independent cont r ibu t ion of adjusted f r u i t s i ze to y i e l d v a r i a t i o n can be in terpreted as an i n d i c a t i o n that the ro le of PP333 in f r u i t enlargement was due to addi t iona l i n h i b i t o r y e f f e c t s not act ing upon e a r l i e r components such as f r u i t set (Table VI I I ) . E. E f fec t of shoot type on bud set No c u l t i v a r d i f f e rences were observed for the numbers of runners and vegetat ive upr igh ts . ' M c F a r l i n ' had more f lowering upr ights than 'Bergman' as was ind ica ted above (Table XI) . Bud set was great ly in f luenced by shoot type and PP333 (Tables XII and XII I ) . Uprights had a higher frequency of bud set and flower bud set than runners. Uprights that flowered the current season ( U « v , set fewer buds and flower buds than upr ights that had not flowered ( U w , Uv«> TABLE X Effect ol PP333 and nitrogen on adjusted means of yield components1 of 'HcFar l in ' and 'Bergman' cranberry PP333 (eg I"1) U 2 U«/U F/U, B/F Y/B lnY 0 4.0 -0.01B 0.014 0.54 0. 12 3.3 75 4. 1 -0.03 -0.006 -0.28 -0 . 17 2. 1 150 4.1 -0.05 -0.007 -0.26 -0 . 1 2.1 PP333 trend NS NS NS L|D L L,D Cult i var X PP333 NS NS NS NS NS NS Ni trogen X PP333 NS NS NS NS NS NS 'The means of the adjusted y ie ld components are residuals from regression using logarithm.-transformed yie ld components. 2 U • no. uprights, lU = no. flowering uprights, F = no. flowers, B » no. f r u i t s , Y = total f ru i t fresh weight. NS = Not s ign i f i can t , L = Linear trend or D = deviation s igni f icant at P < 0.05. 96 TABLE XI Numbers of runners and uprights ( U u M per dm3 for 'HcFar l in ' and 'Bergman' cranberry in 1984 No. vegetative No. flowering uprights per dm2 uprights per dm2 Cult ivar U , v No. runners Total no. shoots HcFarlin 27 7 20 5 2 61 Bergman 36 9 15 2 1 63 Signif icance NS NS » • NS NS ' C l a s s i f i c a t i o n of upright (U,j) by flowering status ( v B non-flowering or « « flowering) * • current and } * previous season. NS = Not s ign i f i can t , or # P < 0.05, «* P < 0.01 and « * * P < 0.001. V TABLE XII Budi per ihoot for runntri end uprights iUi,1) in 19B4 for 'McFarl in ' and 'Bergman' cranberry treated with nitrogen and PP333 Buds per shoot (X) PP333 -(mg l" 1) Runner Uw Uvf U « v U«« 0 44 Bl 66 49 61 75 74 95 96 66 86 150 69 94 93 89 85 Cult i var NS PP333 trend L,D Cult ivar X PP333 NS Ni trogen NS Nitrogen X PP333 NS Runner vs Uprights * * * Uw vs Uvf NS Ufv vs U«« NS Uv vs U« ««* Uv vs Uf x PP333 l in «* ' C l a s s i f i c a t i o n of upright (Uij) by flowering status (v B non-flowering or « = flowering) i = current and j = previous season. NS = Not s i g n i f i c a n t , or * P < 0.05, «* P < 0.01 and * * * P < 0.001. L c Linear trend or deviation (D) s igni f icant at P < 0.05. TABLE XIII Flower bud* per bud in 1984 for 'HcFarlin* and 'Bergean' cranberry treated with nitrogen and PP333. Flower buds per bud (X) PP333 -(ng 1~M Runner Uw 1 Uv* U«„ U*« 0 44 67 BO 51 53 75 49 52 73 51 55 150 ' 65 52 64 52 65 C u l t i v a r NS PP333 trend NS C u l t i v a r X PP333 NS Ni trogen NS Nitrogen X PP333 NS Runner vs Uprights « « « Uw vs U v* ##• U*v vs U*« NS Uv vs U* ** Uv vs Uf X PP333 l i n « « ' C l a s s i f i c a t i o n of upright <Ui,> by flowering status (v = non-flowering or « = flowering) i » current and i - previous season. NS = Not s i g n i f i c a n t , or * P < 0.05, ** P < 0.01 and *** P < 0.001. 99 as r t p o r t t d prev ious ly (Lenhardt and E i t o n , 1976) Eaton, 1 9 7 8) . S imi lar to the reported e f fec t of SADH at 1500 mg l " 1 (Lenhardt and Eaton, 1976), PP333 great ly increased bud set for a l l shoot types but more for the f lower ing upr ights than non-f lowering upr ights (Table XII) . In a d d i t i o n , the f l o r a l induct ion for non-f lowering upr ights was decreased s l i g h t l y by PP333 (Table XII I ) . It i s a new observat ion that upr ights that did not flower in the current season (Uw, U v<) were l ess l i k e l y to set flower buds i f they had not flowered in the past season (Uw) (Table XII I ) . This ind ica tes that although there i s a tendency for a l t e r n a t i o n in f lower ing , some shoots p e r s i s t in the vegetat ive condi t ion for several years . This may be e i ther because such shoots are too vegetat ive to set flower buds or because they are too weak. P333 may have increased bud set by a number of mechanisms. Decreasing crop load as occurred in our study can s u b s t a n t i a l l y increase flower bud set for t ree f r u i t s (Davis, 1957). This promotive e f fec t on bud set was a t t r ibu ted to the removal o f , or i n h i b i t i o n of developing seeds (Chan and C a i n , 1967). Seeds are both powerful s inks for nut r ien ts and sources of growth r e g u l a t o r s , poss ib ly 6A, that can i n h i b i t f l o r a l i n i t i a t i o n (Sachs, 1977; Buban and Faust , 1982). Inh ib i to rs of 6A biosynthes is have been observed to increase bud set in woody plants genera l ly (Stuar t , 1961; Batjer et a l . , 1964; Wi l l i ams, 1972 ). Some reports i n d i c a t e B A - i n h i b i t o r s , such as CCC or t r i ad imefon , increase the leve l of endogenous cy tok in in (Skene, 1968; F le tcher and Arno ld , 1986) or a b s c i s i c ac id (ABA) (Asare-Boamah, 1986). Both cy tok in ins and ABA appear to be involved in flower bud set (Nooden and Weber, 1978; Bernier et a l . , 1981). 100 F. Runner growth 'Bergman' had more upr ights per runner than ' H c F a r l i n ' (0.2 vs . 2.7} P < 0.01) . ' H c F a r l i n ' produces more upr ights on runner growth that has aged several years than on recent growth compared to 'Bergman' (Tallman and Eaton, 1976). PP333 did decrease runner length and shoot dry weight, and increased the number of upr ights per runner (Table XIV). Runners were l i k e l y more a f fec ted than upr ights in t h i s study as they continued growth la te r in the season than upr igh ts . Both the r e s u l t s of t h i s study and a previous report (McArthur and Eaton, 1987b or Chapter 5) i n d i c a t e that PP333 may be useful in the contro l of excessive runnering and a l te rnate bearing in the cranberry . However, the dramatic decrease in y i e l d by PP333 through i t s e f f e c t s on f r u i t set and f r u i t s i z e ind ica tes that more research into the optimum time for i t s a p p l i c a t i o n i s requ i red . In t h i s study, TDP was useful in c l a r i f y i n g the most important cont r ibu tors to y i e l d v a r i a t i o n and the pathway through which treatments and c u l t i v a r s inf luenced y i e l d . The low rate of f l o r a l induct ion ind icated for 'Bergman' in 19B3 provides p r a c t i c a l information to the commercial grower and revea ls a need to re -eva luate the current f e r t i l i z e r rates or other c u l t u r a l p r a c t i c e s that might r e s t r i c t f l o r a l induct ion and thus y i e l d . TABLE XIV Runner growth and upright production in 1984 for 'McFarlin and 'Bergman' cranberry treated with nitrogen and PP333 PP333 Runner (eg l-«> length (cm) Runner dry wt (eg) Uprights per runner 0 2B 331 0.9 75 20 268 2.6 150 19 254 0.9 PP333 trend L L D Cult ivar X PP333 NS NS NS Ni trogen NS NS NS Nitrogen X PP333 NS NS NS NS = Not s ign i f i can t , or L = Linear trend or deviation (D) s igni f icant at P < 0.05. CHAPTER 7 102 GENERAL DISCUSSION As an aid to t h i s d i s c u s s i o n , several f igures have been developed to depict the dose-response of the strawberry or the cranberry to PP333. The f igures were derived from data presented in e a r l i e r chapters , and they w i l l f a c i l i t a t e comparisons between species and among treatments. Numbering protocol of the f igures r e f l e c t s comparisons of the e f f ec ts of PP333 on vegetat ive and f r u i t growth within a species (Figures 1.1 to 1.4 for the strawberry, or Figures 2.1 to 2.3 for the cranberry ) , and between species (Figure 1 vs. F igure 2). F igures 3 and 4 are s imi la r comparisons, but consider the e f f e c t s of NPK leve l and PP333. A. E f f e c t s of i n h i b i t o r s of 6A-b iosynthes is on vegetat ive growth and y i e l d Vegetat ive and f r u i t growth in e i ther the strawberry (Chapter 3 and 4) or the cranberry (Chapter 5 and 6) decreased with the increas ing concentrat ions of PP333 a p p l i e d . Runnering was decreased in the strawberry, and runner growth was decreased in the cranberry. These f ind ings are s imi la r to those reported on the e f f ec ts of PP333 in the strawberry (Stang and Weis, 1984) and on PP333 in woody perennia ls (Tukey, 1981; Shanks, 1981). A l s o , i t was observed that some of the e f f ec ts of PP333 d i f f e r e d between the strawberry and the cranberry . In the strawberry, dry weight per plant did not d i f f e r between c u l t i v a r s , and decreased as the concentrat ion of PP333 increased (Figure 1.1). Runner number was decreased by PP333 a l s o , and poss ib ly accounts for a substant ia l por t ion of the loss in plant dry weight (Figure 1.2). However, leaf growth a lso was responsive to PP333, as ind icated by area Figure 1.1. The effect of PP333 on whole plant dry weight of strawberry. Figure 1 . 2 . The effect of P P 3 3 3 on runnering in strawberry. Runners per plant 8 i 10 46 215 1000 P P 3 3 3 (mg/l) * Totem x Shuksan per l e a l and p e t i o l e l e n g t h , and t h e e f f e c t s of PP333 on leavnt c o n t r i b u t e d t o a l o s s i n p l a n t d ry we igh t ( C h a p t e r 3 and Append ix T a b l e A . I I ) . These o b s e r v a t i o n s r e f l e c t a r e q u i r e m e n t f o r G A - b i o s y n t h e s i s i n bo th r u n n e r and l e a f deve lopmen t ( G u t t r i d g e and Thompson, 1 9 6 3 ) . Root g rowth was a l s o d e c r e a s e d by P P 3 3 3 , but as some p rob lem was e x p e r i e n c e d i n c o l l e c t i n g t h e r o o t s , i t was p o s s i b l e t h a t t h e s e r e s u l t s might not be r e l i a b l e . T h e r e f o r e , c o m p a r i s o n s between t h e e f f e c t s of PP333 on r o o t g rowth and shoo t g rowth were not p o s s i b l e . However , t h e s e f i n d i n g s i n d i c a t e t h a t p r o b l e m s w i t h use of PP333 f o r c o n t r o l of r u n n e r i n g i n the s t r a w b e r r y may be t h a t t h e e f f e c t s a r e not s p e c i f i c o n l y t o r u n n e r deve lopmen t and t h a t t he s i d e e f f e c t s of e x c e s s i v e c o n c e n t r a t i o n s a r e d e t r i m e n t a l t o p l a n t g r o w t h . However , a t a low c o n c e n t r a t i o n of PP333 (46 mg l - 1 ) , r unne r g rowth appea red t o be more r e s p o n s i v e than l e a f g r o w t h , and i n t h i s s t u d y , t h e s i d e e f f e c t s of PP333 at low c o n c e n t r a t i o n s on p l a n t g rowth were not a p p a r e n t l y d e t r i m e n t a l . C u l t i v a r by PP333 i n t e r a c t i o n s on r u n n e r i n g ( F i g u r e 1 . 2 ) , crown number ( F i g u r e 1 . 3 ) , r o o t d ry we igh t and l e a f deve lopmen t ( C h a p t e r 3 and Append ix T a b l e A . I I ) i n d i c a t e d ' T o t e m ' and ' S h u k s a n ' d i f f e r e d i n t h e i r r e s p o n s i v e n e s s t o P P 3 3 3 , but i n bo th c u l t i v a r s , PP333 at 46 mg l ~ l d e c r e a s e d r u n n e r i n g and t he s i d e e f f e c t s d i d not appear to be d e t r i m e n t a l t o e i t h e r c u l t i v a r . The s l i g h t i n c r e a s e i n crown number o b s e r v e d f o r ' T o t e m ' p l a n t s t r e a t e d w i t h PP333 may be b e n e f i c i a l t o y i e l d i n t he f o l l o w i n g year by i n c r e a s i n g s i t e s f o r f l o w e r i n d u c t i o n , but PP333 d i d not have a s i m i l a r e f f e c t on ' S h u k s a n ' , and a p p e a r e d t o s l i g h t l y d e c r e a s e crown number f o r ' S h u k s a n ' . The c u l t i v a r i n t e r a c t i o n w i t h PP333 f o r t he number of r u n n e r s s u g g e s t t h a t ' S h u k s a n ' was a b l e t o p r o d u c e more r u n n e r s t h a n ' T o t e m ' as t he c o n c e n t r a t i o n of PP333 i n c r e a s e d . S i m i l a r o b s e r v a t i o n have been r e p o r t e d by o t h e r s ( A t k i n s o n et a l . , 1 9 8 6 ) , and t h e s e Figure 1.3. The effect of PP333 on crown number of strawberry. Crowns per plant . 1.5 -1.0 -0.5 0.0' 10 46 215 PP333 (mg/l) * Totem x Shuksan 1000 Figure 1.4. The effect of PP333 on yield of strawberry. Fruit fresh weight per plant (g) 46 215 PP333 (mg/l) 1000 * Totem 2 Shuksan 106 d i f f e r e n c e s may be due to d i f fe rences in timing of runner i n i t i a t i o n (Chapter 3) . In the strawberry, f r u i t f resh weight per plant (y ie ld) appeared to be increased by PP333 at 10 or 46 mg 1~* compared to c o n t r o l s , but no s i g n i f i c a n c e test was performed to confirm th is as a 0 leve l of PP333 could not be included in trend ana lys is using log sca le concentrat ions (Chapter 3). Y ie ld decl ined with increas ing PP333 concentrat ions (Figure 1.4). This resu l t appeared to be due a delay in f r u i t r i p e n i n g , and in t h i s study, few f r u i t ripened on plants t reated with 1000 mg l " 1 of PP333 (Chapter 3). PP333 unaccountably increased the number of achenes per f r u i t , and poss ib ly because of t h i s , f r u i t s i ze was increased. The observat ion that PP333 i n h i b i t e d pol len germination i s d i f f i c u l t to r e c o n c i l e with the observat ion of increased achene development for plants treated with PP333, but i t may be that PP333 was appl ied at a time af ter f e r t i l i z a t i o n had already occurred , or when some pol len was not exposed, thus permit t ing normal germinat ion. The increase in achene number was poss ib ly as a resu l t of a decrease in achene abor t ion , and may be due to a decrease in competit ion for nut r ients between vegetat ive and reproduct ive ' s i n k s ' . That th is may be so i s ind icated by the general decrease in vegetat ive growth already discussed and also by the observed delay in leaf senescence for plants treated with PP333. PP333 decreased ethylene b iosynthes is and increased the l e v e l s of polyamines that delay senescence in apple seedl ings and may have had s im i la r e f f e c t s in the strawberry f r u i t (Steffens and Wang, 1986). Comparison of the e f f e c t s of PP333 Dn vegetat ive and f r u i t growth in the strawberry suggests that both are a f fected in a s im i la r manner. Two observat ions suggest that fur ther research should be conducted in the assessment of the use of PP333 as an a l t e r n a t i v e to pruning. These are Figure 2.1. The effect of PP333 on whole plant dry weight of cranberry. Ory weight per plant (g) Figure 2.2. The effect of PP333 on shoot number of cranberry. Shoots per plant 20 i • 200 400 600 800 1000 1200 1400 PP333 (mg/l) McFarlin 2 Ben Lear that PP333 i t 46 ng l " 1 decreased runntr ing without any detrimental e f f e c t s on leaf growth, and PP333 nay have increased y i e l d when appl ied at 10 or 46 eg l " 1 . In glasshouse s tudies with the cranberry , ' H c F a r l i n ' had a greater dry weight per plant than 'Ben L e a r ' , but dry weights for both were great ly decreased at the lowest concentrat ion of PP333 (Figure 2 .1 ) , and, as evident from an e f fec t on shoot length , within 3 weeks of a p p l i c a t i o n (Chapter 5) . Both shoot and root dry weights were decreased, but shoot growth was more responsive to PP333, as observed by the decrease in the shoot i root r a t i o with increas ing concentrat ions of PP333. This nay be due to the nethod of a p p l i c a t i o n , but other s tudies ind ica te that shoot growth i s genera l ly more responsive than root growth to i n h i b i t o r s of GA-b iosynthes is (Froggatt et a l . , 1982). The decrease in shoot dry weight in the cranberry was even though shoot number was increased by PP333, with a s i g n i f i c a n t i n t e r a c t i o n i n d i c a t i n g shoot number was increased more for 'Ben Lear ' than for ' H c F a r l i n ' (Figure 2 .2 ) . Shoot e longat ion was apparently more responsive than leaf development, as suggested by the observat ions that area per l e a f , leaves per shoot (Chapter 5 ) , and leaves per plant (Appendix Table A.IV) were decreased less by PP333 in comparison to mean shoot length and shoot length per p lan t . It was observed that many of the leaves overlapped each other on shoots of cranberry plants t reated with PP333. This f ind ing suggests that a decrease in photosynthesis may r e s u l t from leaves shading each other . Leaf crowding a lso may increase leaf s u s c e p t i b i l i t y to diseases by i n h i b i t i n g a i r flow around stems and leaves . Besides the i n h i b i t i o n of shoot a t t r i b u t e s mentioned above, PP333 had profound e f f e c t s on other aspects of plant growth. For example, PP333 increased branching, and bud set within 7-8 weeks. Under the glasshouse 109 condi t ions used in th is study, shoot and runner growth of untreated plants was vigorous and bud set was minimal. The reason for th is aspect of a l tered growth habit induced by PP333 has not been invest igated in cranberry , but i t i s a general observat ion that GA concentrat ions are higher in plants when growing rap id ly under long photoperiods and warm temperatures (Goodwin, 1978). A l s o , i n h i b i t o r s of GA-biosynthesie have been observed to decrease shoot e longat ion and induce bud set of woody plants grown under s im i la r growth condi t ions (Chapter 5) . In the present study, the r e s u l t s suggest that i n h i b i t i o n of GA b iosynthes is induced bud s e t , but i t was not poss ib le to determine i f buds were formed in d i rec t response to an i n h i b i t i o n of GA-biosynthesis in plants treated with PP333, or by another e i ther d i rec t or i n d i r e c t e f fec t of PP333 on another aspect of plant phys io logy . In the f i e l d study of cranberry , vegetat ive growth was less responsive to PP333 than f r u i t growth (Chapter 6). Y ie ld decl ined with increas ing rates of PP333 (Figure 2 .3 ) . The response of f r u i t to PP333 in th is study was more s imi la r to that of p lants in the glasshouse study (Figure 2.1) mentioned above than that of the upr ights the f r u i t were c o l l e c t e d from (Chapter t>). This appeared to be a consequence of the timing of PP333 a p p l i c a t i o n , as most of the upright growth and e longat ion , except bud s e t , was completed about the time of f u l l bloom (Chapter 6) . The r e s u l t s from the glasshouse studies with cranberry suggest e a r l i e r a p p l i c a t i o n would have decreased upright length s u b s t a n t i a l l y . PP333 decreased runner growth, poss ib ly as runners continue growing la te r in the season than upr ights . A l s o , shoot growth in the season subsequent to that of PP333 a p p l i c a t i o n was decreased, which ind icated an e f fec t by PP333 during the bud development stage of upr ights . That there were some e f f e c t s on vegetat ive growth ind ica ted PP333 was absorbed by upr igh ts , and 110 Figure 2.3. The effect of PP333 on yield of cranberry. 3.0 i 2.5. 2.0 1.5 1.0 0.5 0.0 Fruit fresh weight (g/upright) : ---i 1 i * McFarlin 50 100 PP333 (mg/l) 3 Bergman 150 200 > th is observat ion suggested that the lack of an e f fec t on shoot elongation in year of a p p l i c a t i o n was due to timing of a p p l i c a t i o n . As in the glasshouse s t u d i e s , PP333 increased bud set of upr ights in the f i e l d , but t h i s was without decreasing shoot length , and a lso regard less of shoot type (Chapter 6) . That the i n h i b i t i o n of shoot e longat ion is not required for bud set to occur , suggests PP333 might be appl ied la te r than in th is study to avo id , i f p o s s i b l e , the negative e f f e c t s on f r u i t development. Studies on growth regulators in f r u i t or f r u i t seeds i n d i c a t e that GA-biosynthesis may be greater or more important to f r u i t development at various times during the season (Goodwin, 1978). If f r u i t growth i s not i n h i b i t e d by PP333, a potent ia l benef i t of using PP333 in the f i e l d w i l l be increased flower bud se t . The per iod of f l o r a l induct ion i s suggested to las t from about the last week of June to the f i r s t week of July (Roberts and Struckmeyer, 1943; Eaton, 1978), and the t iming of PP333 a p p l i c a t i o n may have to be within t h i s period for the best r e s u l t s . This may l i m i t the potent ia l benef i t of PP333 on bud se t , but fur ther i n v e s t i g a t i o n is required to determine the e f fec t of spray t iming on upright and f r u i t growth. P o s s i b l y , an e a r l i e r a p p l i c a t i o n of PP333 before f lowering and at a lower concentraion may increase bud set without detrimental e f f e c t s on upright e longat ion or f r u i t growth. PP333 decreased f l o r a l induct ion for non-f lowering uprights but not f lowering uprights (Chapter 6). This observat ion suggests that PP333 may have had an e f fec t on the r e d i s t r i b u t i o n o f , or competit ion for nutr ients or growth regu la tors that are essent ia l for f l o r a l i nduc t ion . A l t e r n a t i v e l y , PP333 may have simply promoted bud set of upr ights af ter the period for f l o r a l i nduc t ion . The promotion of flower bud set by f lowering upr ights and the decrease in f r u i t s i z e and set by PP333 suggests an involvement of GA in the a l te rnate bearing of cranberry as has 112 been ind icated for other f r u i t crops (Chan and C a i n , 1967; Eaton, 1978; Monselise and Boldschmidt, 19B2). As discussed above, PP333 decreased vegetat ive and f r u i t growth in a s i m i l a r manner in e i ther the strawberry or the cranberry , but some d i f f e rences were observed in the respnsiveness between vegetat ive and f r u i t growth. S i m i l a r l y , the strawberry, a herbaceous perennial and the cranberry , a woody p e r e n n i a l , d i f f e r e d in the i r response to PP333 in various ways. P o s s i b l y , the d i f f e rences in response to PP333 rates observed in the strawberry and the cranberry r e f l e c t d i f fe rences in the nature of these two diverse s p e c i e s , such as in uptake, t r a n s l o c a t i o n and metabolism of PP333, but other fac to rs may have confounded these r e s u l t s . Comparison of these two f r u i t p lants in the i r response to PP333 is d i f f i c u l t as the i r c u l t u r a l management was d i f f e r e n t . For example, the strawberry plants f r u i t e d ins ide a greenhouse without p o l l i n a t o r s , while the e f f e c t s of PP333 on f r u i t in the cranberry were determined in a f i e l d with p o l l i n a t o r s present . PP333 was appl ied to both species as a f o l i a r spray without covering the pot s o i l su r face , but, s ince the cranberry plants were grown in sand and the strawberry plants in s o i l , PP333 may have reached the cranberry p l a n t s ' roots more e a s i l y . This may be a factor in d i f f e rences in the degree of responsiveness as PP333 i s more r a p i d l y taken up and t rans located by roots than by shoots (Froggatt et a l . , 1982). In a d d i t i o n , the cranberry p lants produced by s t r i k i n g cut t ings were s u b s t a n t i a l l y smaller than the strawberry crowns obtained, and in the cranberry , only the current growth was included in plant dry weight. Thus, these d i f f e rences confound comparisons of responsiveness to actual rates of PP333 between the strawberry and the cranberry. Some of the e f f e c t s of PP333 in the strawberry appeared to be q u a l i t a t i v e l y d i f f e r e n t than those in the cranberry and appeared to be unrelated to the i r c u l t u r a l treatment. For example, despite a very a l igh t increase in crowns for one c u l t i v a r in the strawberry, the general e f fec t of PP333 was to decrease the number of l a t e r a l branches by decreasing runner ing. Conversely , PP333 increased the number of branches in the cranberry . This d i f fe rence between strawberry and cranberry suggests that PP333, e i ther d i r e c t l y or i n d i r e c t l y , acted in an opposite fashion on fac to rs that control l a t e r a l bud outgrowth for these two spec ies . Poss ib ly GA has a d i f f e r e n t ro le in each plant type. GA might promote shoot e longat ion of the cranberry runner, but might a lso be a factor in the i n h i b i t i o n of l a t e r a l bud outgrowth. The increased number of uprights on cranberry runners in the f i e l d treated with PP333 supports t h i s suggestion (Chapter 6). In the strawberry, GA might be required to promote runner or crown bud outgrowth and appeared to be also required for shoot e longat ion . Observations during these studies a lso suggest that f r u i t of the cranberry might be more responsive to PP333 than f r u i t of the strawberry. IAA was suggested to be the primary growth regulator involved in strawberry f r u i t enlargement and development (N i tsch , 1950)), while GA appeared to have a minor ro le in receptac le development (Thompson, 1964). Few studies have invest igated the e f f e c t s of GA on f r u i t development in the cranberry , but GA appears to play an important ro le in f r u i t development (Develin and Demoranvi11e, 1967). The r e s u l t s of Chapters 3 and 6 suggest that GA has a ro le in f r u i t development in both the strawberry or cranberry , but 6A may have a larger ro le in f r u i t development in the cranberry than in the strawberry. In the strawberry, c u l t i v a r d i f f e rences in vegetat ive growth and response to PP333 or CCC were observed, but general ly vegetat ive growth was more responsive to PP333 than to CCC (Chapter 3) . CCC had l i t t l e 114 e f fec t on plant growth, but s l i g h t l y decreased runner ing. Some of the e f f e c t s of PP333 reported here are s imi la r to those reported for CCC at much higher concentrat ions (Buttr idge et a l . , 1966). At equal concentrat ions (mg l " 1 ) , PP333 decreased runnering more than CCC and, at the concentrat ions in t h i s study, appeared to have more b i o l o g i c a l a c t i v i t y than CCC. Although both PP333 and CCC i n h i b i t SA-b iosyn thes is , the i r mode of act ion d i f f e r s (Dicks, 1980; Hedden and Braebe, 1985). A l s o , some studies ind ica te that CCC may be rap id ly metabolized in plants (Lawrence, 1984), while PP333 may be slowly metabolized (S te r re t t , 1985). These two fac tors might have contr ibuted to the observed d i f fe rences between CCC and PP333 in th is study. In the cranberry , PP333 was e f f e c t i v e at the lowest concentrar t ion a p p l i e d , while SADH had no e f fec t at i t s highest concent ra t ion . As mentioned above, PP333 may be slowly metabol ized, but SADH a lso appears to be slowly metabolized (Lawrence, 1984). Therefore , t h i s was un l i ke ly to have been a factor in the d i f f e ren t responsiveness to each chemical in the cranberry . Their d i f f e r e n t mode of act ion poss ib ly accounts for the e f fec t i veness of PP333 compared to SADH at the concentrat ions used in th is thes is (Dicks, 1980; Hedden and Braebe, 1985). B. E f f e c t s of f e r t i l i z e r rate on vegetat ive growth and y i e l d Under glasshouse c o n d i t i o n s , vegetat ive growth for e i ther |he strawberry (Chapter 3; Appendix Table A . I ) , or the cranberry (chapter 5) was promoted by the higher rate of NPK f e r t i l i z e r a p p l i c a t i o n . The increased root and shoot dry weight, leaf area and crown number for strawberry and increased shoot dry weight and shoot number for cranberry suggest that in new f i e l d p lant ings of e i ther crop, the higher f e r t i l i z e r a p p l i c a t i o n rate would be des i rab le as i t would st imulate more rapid plant 1 1 5 and ctnopy development. Increases in number of crowns in strawberry end in number of branches in cranberry should have a p o s i t i v e in f luence on y i e l d in the fo l lowing season as both are potent ia l s i t e s for flower development for the subsequent season. In es tab l ished p lant ings of e i ther strawberry or cranberry , the benef i ts of the higher f e r t i l i z e r level may p o t e n t i a l l y be o f fse t by the undesirable e f f e c t s . For example, an increased number of runners and runner crowns per strawberry plant in the l a t t e r period of growth can increase labour costs for pruning (Chapter 3 and 4) . If l e f t unpruned, la te runner crowns are less product ive and crowd estab l ished crowns (Shoemaker, 197S). The e f fec t of a high rate Df NPK f e r t i l i z e r a p p l i c a t i o n on a mature f i e l d of c ranberr ies is more l i k e l y to increase runner growth than upright production and, as in strawberry, t h i s i s l i k e l y to r e s t r i c t y i e l d . In the f i e l d study with cranberry , no e f fec t of N f e r t i l i z a t i o n was observed e i ther for vegetat ive or f r u i t growth (Chapter 6). The t r a i l i n g nature of runners often r e s u l t s in upr ights in one sect ion of a bog being several metres from i t s vine roo ts . Since the N treatment was appl ied to randomly assigned p lo ts only 1 m2 in area , i t may not have been poss ib le to detect a l o c a l i z e d N e f f e c t . Poss ib ly e i ther larger p lo ts or a s p l i t -plot design would have improved detect ion of N e f f e c t s . In the strawberry, f r u i t growth was less responsive to the rate of » NPK f e r t i l i z e r than vegetat ive growth. The only s i g n i f i c a n t e f fec t of the high NPK on f r u i t growth was to increase the number of unripe f r u i t l e f t at the end of the study (Chapter 3). This observa t ion , and the delay in leaf senescence observed, suggest the high f e r t i l i z e r leve l may have increased the leve l of endogenous cy tok in ins in the plants or decreased the competi t ion between ' s i n k s ' for nut r ients (Leopold and Kriedemann, 1 1 6 i975; Zeevart et a l . , 1979; Marschener, 1983). A comparison between strawberry and cranberry for the response of f r u i t growth to f e r t i l i z e r l e v e l s was not poss ib le as only vegetat ive cut t ings were used in the glasshouse cranberry f e r t i l i z e r study and, as mentioned, the N treatment in the cranberry f i e l d study did not produce any s i g n i f i c a n t response. In the glasshouse studies with cranberry , vegetat ive growth was promoted by peaty s o i l compared to sandy s o i l and there was no s i g n i f i c a n t i n t e r a c t i o n between s o i l type or f e r t i l i z e r rate (Chapter 5). The increased number of shoots and shoot dry weight promoted by these treatments suggests tha t , during the f i r s t year of growth of a new f i e l d p l a n t i n g , canopy establishment would be improved with a high rate of rate of f e r t i l i z e r a p p l i c a t i o n , but decreased by sanding. Sanding i s sometimes recommended during bog establishment to leve l depress ions , and to st imulate root ing (Shoemaker, 1978). Genera l ly , the e f f e c t s of f e r t i l i z e r level on the growth of e i ther the strawberry or cranberry in t h i s thes is confirm those that have been reported in the l i t e r a t u r e (Chapters 1 and 2) . In the strawberry, dry weight per plant was increased by the high NPK f e r t i l i z e r l e v e l , but t h i s promotive e f fec t decreased as the concentrat ion of PP333 increased (Figure 3 .1) . This s i g n i f i c a n t f e r t i l i z e r by PP333 i n t e r a c t i o n is s i m i l a r to that for leaf area per plant and resul ted because the high f e r t i l i z e r concentrat ion increased the number of leaves for the parent crown and root dry weight when PP333 was appl ied at low r r a t e s , but th is promotive e f fec t was diminished by PP333 at 215 or 1000 mg l - 1 (Chapter 3; Appendix Table A . I I ) . Thus, i t appeared that the potent ia l benef i ts of an increased rate of f e r t i l i z e r a p p l i c a t i o n on leaf development and plant growth were decreased and lost at high concentrat ions of PP333 because the i n h i b i t o r y e f f ec ts of PP333 were not s p e c i f i c to runner ing. It a lso appeared that PP333 did not modify the 117 Figure 3.1. The effect of PP333 and NPK on whole plant dry weight of strawberry. Dry weight per plant (g) 10 * Low NPK 46 215 PP333 (mg/l) * High NPK 1000 Figure 3.2. The effect of PP333 and fertilizer on runnering in strawberry. Runners per plant 8 i 4 -2 -0 -10 46 215 1000 PP333 (mg/l) * Low NPK * High NPK 118 e f f e c t s of f e r t i l i z e r rate on runnering or crown branching (Figures 3.3 and 3 .4) . This suggests that the increased rate of f e r t i l i z e r does not increase runnering by increas ing BA l e v e l s . Instead, runnering appears to be promoted by increased leaf production as the r a t i o of runners to leaves does not change with the rate of f e r t i l i z e r a p p l i c a t i o n (Chapter 4). Although the benef i t of high f e r t i l i z e r leve l was lost at high rates of PP333, at the low concentrat ion of 46 mg l " 1 , runnering appeared to be i n h i b i t e d more than leaf development and leaf area was greater than for control plants grown with a low f e r t i l i z e r ra te . Thus, low rates of PP333 may be a useful adjunct to high rates of f e r t i l i z e r a p p l i c a t i o n to promote rapid canopy development without excessive runner growth. Y ie ld was decreased by PP333 in a concentrat ion dependent manner in both the strawberry and the cranberry , and NPK leve l did not modify the e f fec t of PP333 on y i e l d (Chapter 3; Figure 3.4) . Thus, i t appeared that PP333 did not s h i f t f e r t i l i z e r - s t i m u l a t e d vigor from vegetat ive to f r u i t growth. S i g n i f i c a n t i n t e r a c t i o n s between PP333 and f e r t i l i z e r for f r u i t s i ze and achene number per f r u i t resu l ted because these a t t r i b u t e s were increased by PP333 up to 215 mg 1 _ 1 , but at 1000 mg l " 1 PP333 plus high NPK decreased f r u i t s i ze and achene number in an add i t i ve fashion by a delay on f r u i t r ipening (Chapter 3). Dry weight per shoot was increased in the cranberry by the high NPK , but, as in the strawberry, t h i s promotive e f fec t diminished with increas ing concentrat ions of PP333 (Chapter 5; Figure 4 .1 ) . The s i g n i f i c a n t f e r t i l i z e r by PP333 i n t e r a c t i o n in shoot dry weight was l a r g e l y as a r e s u l t of the e f fec t of PP333 on stem growth (stem dry weight) and not leaf development (Appendix Table A . V ) . Leaf dry weight was decreased by PP333, but no i n t e r a c t i o n between NPK concentrat ion and PP333 was observed. Figure 3.3. The effect of PP333 and fertilizer on crown number of strawberry Crowns per plant 119 10 * Low NPK 46 215 PP333 (mg/l) * High NPK 1000 Figure 3.4. The effect of PP333 and fertilizer on yield of strawberry. Fruit fresh weight per plant (g) 10 * Low NPK 46 215 PP333 (mg/l) * High NPK 1000 Figure 4.1. The effect of PP333 and fertilizer on cranberry shoot dry weight Shoot dry weight (g) 51 4 -0 1 2 3 4 5 6 PP333 (mg/pot) * Low NPK * High NPK Figure 4.2. The effect of PP333 and fertilizer on shoot number of cranberry. Shoots per plant 40 | 1 0 1 2 3 4 5 6 PP333 (mg/pot) * Low NPK * High NPK 121 The number of shoots per plant was increased by both the high NPK and PP333, but no i n t e r a c t i o n was evident (Figure 4 .2 ) . This observat ion suggests that NPK or PP333 increased l a t e r a l bud outgrowth by d i f f e r e n t mechanisms. S i m i l a r l y , in the strawberry, leaf senescence was decreased by both high NPK or PP333 without any i n t e r a c t i o n between them. These responses in both the cranberry or the strawberry suggest that the p l a n t s ' cy tok in in l e v e l s were increased but t h i s was not confirmed. Increased plant cy tok in in l e v e l s were found in grapevines treated with CCC (Skene, 1968). P o s s i b l y , a side e f fec t of PP333 was a decrease on the competit ion for nut r ients between ' s i n k s ' that involved cy tok in ins or other growth r e g u l a t o r s . In the cranberry , peaty s o i l and, in a s imi la r manner, the high f e r t i l i z e r rate both st imulated shoot growth. This observat ion was not unexpected but made more i n t e r e s t i n g when one had a s i g n i f i c a n t i n t e r a c t i o n with PP333 the other did not. While neither peaty s o i l nor high NPK af fected bud s e t , the high NPK decreased f lowering (Chapter 5). This may have been by a l t e r i n g competit ion for nut r ients or growth regulators necessary for f l o r a l induct ion between vegetat ive and reproduct ive ' s i n k s ' , and is s im i la r to some other reported f ind ings (Bernier et a l . , 1981). This observat ion could be an important one to cranberry growers who must decide what kind and how much of a f e r t i l i z e r they must add to the i r f i e l d s each year to improve flower production and a cropping. Unfor tunate ly , no e f fec t of ni trogen was apparent on'growth or f r u i t i n g of upr ights or runners in the f i e l d (Chapter 6; Figure 4 .3 ) , so the e a r l i e r observat ions of an i n t e r a c t i o n between f e r t i l i z e r rate and PP333 on f l o r a l induct ion in the glasshouse study (Chapter 5) could not be conf irmed. Further i n v e s t i g a t i o n of the e f f e c t s on f l o r a l induct ion in the cranberry of the amount of NPK f e r t i l i z e r , t iming of a p p l i c a t i o n and 122 Figure 4.3. The effect of PP333 and fertilizer on yield of cranberry. Fruit fresh weight (g/upright) 3.0 i 2.5 2.0 1.5 1.0 0.5 0.0 i * i - i * __j * Low NPK 50 100 PP333 (mg/l) * High NPK 150 200 123 t h e s o u r c e o f n i t r o g e n i n t h e NPK a p p e a r s t o be w a r r a n t e d . C . Y i e l d c o m p o n e n t s In t h e s t r a w b e r r y , t h e m a i n c o n t r i b u t o r s t o y i e l d v a r i a t i o n w e r e , i n o r d e r o f i m p o r t a n c e : t h e n u m b e r o f t r u s s e s p e r p l a n t , f o l l o w e d by t h e n u m b e r o f r i p e f r u i t s p e r p l a n t , number o f a c h e n e s p e r f r u i t a n d t h e n u m b e r o f f r u i t s p e r p l a n t ( C h a p t e r 4 ) . T h e o t h e r a d j u s t e d v a r i a b l e s a l l made s i g n i f i c a n t c o n t r i b u t i o n s b u t a c c o u n t e d f o r m i n o r a m o u n t s o f y i e l d v a r i a t i o n . T h u s , u n d e r t h e c o n d i t i o n s o f t h i s s t u d y , y i e l d was m o s t l i m i t e d by e n v i r o n m e n t a l f a c t o r s d u r i n g t h e p r e v i o u s s e a s o n t h a t i n f l u e n c e d t h e p l a n t ' s a b i l i t y t o r e s p o n d t o f l o r a l i n d u c t i o n , a n d f a c t o r s d u r i n g t h e c u r r e n t g r o w i n g p e r i o d t h a t i n f l u e n c e d f r u i t d e v e l o p m e n t , s u c h a s p o l l i n a t i o n . P o s s i b l y , t h e r e l a t i v e l y s m a l l c o n t r i b u t i o n o f c r o w n n u m b e r t o y i e l d v a r i a t i o n i n t h i s s t u d y w o u l d b e e n i n c r e a s e d i n a s u b s e q u e n t s e a s o n i f t h e p l a n t s h a d b e e n m a i n t a i n e d , a s c r o w n s a r e t h e p o t e n t i a l s i t e s f o r t r u s s a n d f l o w e r b u d d e v e l o p m e n t . In t h e c r a n b e r r y , f r u i t s e t was t h e m a i n c o n t r i b u t o r t o y i e l d v a r i a t i o n f o l l o w e d by f r u i t s i z e a n d f l o w e r s p e r f l o w e r i n g u p r i g h t ( C h a p t e r 6 ) . T h e s e f i n d i n g s a r e s i m i l a r t o t h o s e i n t h e s t r a w b e r r y s t u d y a n d many o t h e r s t u d i e s , i n t h e s e n s e t h a t f a c t o r s t h a t i n f l u e n c e t h e a b i l i t y o f p l a n t s t o r e s p o n d t o f l o r a l i n d u c t i o n o r t h e p r e s e n c e o f p o l l i n a t o r s o f t e n c o n t r i b u t e t o y i e l d v a r i a t i o n . U p i g h t d e n s i t y a n d p r o p o r t i o n o f u p r i g h t s d i d n o t make s i g n i f i c a n t c o n t r i b u t i o n s t o y i e l d v a r i a t i o n , b u t t h e means f o r u p r i g h t d e n s i t y i n t h i s t h e s i s w e r e s u b s t a n t i a l l y h i g h e r c o m p a r e d t o t h o s e i n some r e p o r t s ( E a t o n a n d K y t e , 1 9 7 8 ; Y a s a n d E a t o n , 1 9 8 2 ) . T h e u n a d j u s t e d m e a n s f o r p r o p o r t i o n o f u p r i g h t s f l o w e r i n g w e r e s l i g h t l y l o w c o m p a r e d t o some r e p o r t s ( E a t o n a n d K y t e , 1978) b u t h i g h e r t h a n i n o t h e r s ( Y a s a n d E a t o n , 1 9 8 2 ) . A l o w 124 proport ion of upr ights f lowering sometimes occurs in crowded stands of upr ights due to the e f f e c t s of shading on photosynthesis . Such an e f fec t appeared poss ib le in the f i e l d s in the present study. D. E f f e c t s of treatments on y i e l d components In the atrawberry, tha r e a u l t i from TDP provided new information on the e f f e c t s of NPK on runner ing, and confirmed some of the f ind ings discussed e a r l i e r . An increase in the number of runner crowns per plant with high NPK was not through an increase in the number of runners formed per leaf as might be expected with a promotion of runnering with growth regulators l i k e GA 3 and cy tok in in (Braun and Kender, 1985). Instead, as there were more leaves formed with the high NPK, there was a proport ionate increase in runners and thus, runner crowns formed (Chapter 3 and 4). This does not ru le out the p o s s i b i l i t y of a growth regulator i n t e r a c t i o n with nutr ient l e v e l s on runner production (Woolley and Wareing, 1972) but i t does appear from these r e s u l t s that the strawberry plant maintains some balance between leaf and runner formation at d i f f e ren t l e v e l s of s o i l f e r t i l i t y that does not n e c e s s a r i l y involve an e f fec t of growth regula tors on l a t e r a l bud i n h i b i t i o n . In the strawberry, PP333 accounted for a substant ia l port ion of y i e l d v a r i a t i o n and TDP was useful in c l a r i f y i n g how treatment e f f e c t s inf luenced y i e l d i n d i r e c t l y by act ions on y i e l d components (Chapter 4). There were many small cont r ibu t ions by treatments to y i e l d v a r i a b i l i t y , some of which o f fse t each other and, thus ind icated component compensation. It was not p o s s i b l e to sort the i n t e r a c t i o n s between these components as the values were computed as a remainder from the row sums of squares, and therefore a s i g n i f i c a n c e test was not performed (Baumann and Eaton, 1986). The e f fec t of PP333 on leaf area , number of r ipe f r u i t and 125 number of achenes per f r u i t were more c l e a r l y d i s t i n g u i s h a b l e as having an e f fec t on y i e l d v a r i a t i o n . Leaf development at the high concentrat ion of PP333 appl ied appeared to be r e s t r i c t e d and thus, PP333 might have decreased y i e l d by decreasing the amount of photosynthesis taking p lace . The delaying e f fec t of PP333 on berry development accounted for a major con t r ibu t ion to the decrease in y i e l d observed as was also shown by TDP. In the cranberry , TDP a t t r ibu ted a substant ia l amount of y i e l d v a r i a t i o n in the f i e l d study to the PP333 i n h i b i t i o n of f r u i t set (Chapter 6). Although i t was not poss ib le to sort the cont r ibut ions of each component of the value for the c r o s s - p r o d u c t s , i t might be i n f e r r e d , s ince there was l i t t l e e f fec t of PP333 on upright vegetat ive growth, that f r u i t s i ze accounted for much of th is value. Therefore , i t i s reasonable to conclude that the e f fec t of PP333 on f r u i t s i ze appeared to be of a s imi la r nature to that of PP333 on f r u i t se t . A small but s i g n i f i c a n t independent e f fec t of PP333 on f r u i t s i ze suggests again , as in the strawberry study (Chapter 3), that PP333 may inf luenced y i e l d by some e f fec t other than a decrease in BA b i o s y t h e s i s . E. In teract ions between PP333 and growth regulator treatments Some of the e f f e c t s of PP333 were decreased or reversed by BA 3 treatment, such as with seed germination in B. napus (Chapter 3) , and for bud set and shoot e longat ion in the cranberry (Chapter 5) . AC 94,377 a lso decreased some of the e f f e c t s of PP333 in the cranberry , but i t was less e f f e c t i v e than GA 3 at equal concentrat ions (mg l " 1 ) . It was not poss ib le to determine i f AC 94,377 was act ing on plant growth the same as 6 A 3 , and unfor tunate ly , i t s mode of act ion has not been repor ted . These f ind ings ind ica te that some e f f e c t s of PP333 can be decreased, but i t was also observed that nei ther AC 94,377 nor GA 3 decreased the e f fect Df PP333 on 126 shoot dry weight. In a d d i t i o n , p lants treated with e i ther GA 3 or AC 94,377 did not resume the i r normal appearance. This might have been due to excessive concentrat ions of these two chemicals , but these and various other observat ions in t h i s thes is ind ica te that PP333 may be a f fec t ing growth by a means other than the i n h i b i t i o n of SA-b iosyn thes is . Such observat ions include a delay in leaf senescence and f r u i t r ipening) increased leaf product ion; increased achene set (or a decrease in achene abort ion) (Chapter 3); treatment e f f e c t s on the orthogonal ized y i e l d components af ter the e f fec t of PP333 on e a r l i e r components had been considered (Chapters 4 and 6); and the increased branching of shoots in the cranberry . PP333 has been reported as being capable of a l t e r i n g various aspects of plant phys io logy , e i ther d i r e c t l y or as a consequence of the i n h i b i t i o n of GA b iosynthes is (Da lz ie l and Lawrence, 1984; Rademacher et a l . , 1985; Stef fens and Wang, 1986; Wang et a l . , 19B6). Although not invest iga ted for PP333, i t has been demonstrated that some i n h i b i t o r s of GA-biosynthesis increase the plant l e v e l s of cy tok in in (Skene, 1968; F letcher and Arno ld , 1986). It was not poss ib le e i ther in the strawberry or in the cranberry tD a t t r ibu te a l l of the e f f e c t s Df PP333 s p e c i f i c a l l y to the i n h i b i t i o n of GA-b iosynthes is . F. Potent ia l use of PP333 in strawberry and cranberry The r e s u l t s from Chapter 3 suggest PP333 at 46 mg 1 _ 1 decreased runnering more e f f e c t i v e l y than CCC at 1000 mg 1 _ 1 . Since such' a low rate of PP333 decreases runnering without causing any detr imental e f f e c t s to canopy development or decreasing y i e l d , PP333 appears to have potent ia l as an a l t e r n a t i v e tD pruning for control of runnering in strawberry. Hence, PP333 might be used as an adjunct to a high rate of f e r t i l i z e r app l i ca t ion to promote rapid canopy development without increas ing labour requirements 127 for per iod ic runner removal. Further research towards a su i tab le range of concentrat ions of PP333 in strawberry should consider l e v e l s between 25 and 100 mg l " 1 . The a p p l i c a t i o n of low concentrat ions of PP333 about f u l l bloom did not have any detr imental e f f e c t s on y i e l d , but an e a r l i e r or l a te r a p p l i c a t i o n may prove to be super io r . A l s o , s o i l a p p l i c a t i o n may decrease the e f f e c t s of PP333 on f r u i t r ipen ing and pol len germination Since s o i l residues were ac t ive a few months af ter a p p l i c a t i o n , care fu l management of a p p l i c a t i o n rates would be requ i red . The e f f e c t s of PP333 at low concentrat ions on f l o r a l induct ion of strawberry have not been repor ted , but, s ince crown branching was s l i g h t l y increased in th is study, some b e n e f i c i a l e f f e c t s on f lowering in subsequent seasons could be possi b le . In the cranberry , PP333 promoted bud set and flower bud set under glasshouse c o n d i t i o n s . Since bud set and f l o r a l induct ion normally are d i f f i c u l t to a t ta in in c ranber r ies grown in a glasshouse, PP333 might be an aid to study the i n t e r a c t i o n of mineral n u t r i t i o n , and other environmental f a c t o r s such as temperature, photoper iod, and water s t r e s s , on bud set and f l o r a l i n d u c t i o n . In woody ornamentals grown in g lasshouses, PP333 might be useful to increase the number D f flower buds and branches per p l a n t , and to decrease shoot length. Other growth i n h i b i t o r s are used for these purposes at present , but PP333 appears to be e f f e c t i v e at lower concentrat ions than e i ther CCC or SADH. The r e s u l t s of a p p l i c a t i o n of PP333 to f i e l d cranberr ies again ind icated PP333 was e f f e c t i v e at inducing bud set (Chapter 6). However, the t iming of a p p l i c a t i o n appeared to be a c r i t i c a l factor in th is study as a p p l i c a t i o n at f u l l bloom had l i t t l e e f fec t on current shoot growth and resu l ted in a large decrease in f r u i t s e t , f r u i t s i z e and y i e l d . PP333 might be useful in cranberry production for the control of 128 runner growth as an a l t e r n a t i v e to pruning or as an agent to contro l a l te rnate bear ing , but fur ther research i s required to determine an appropriate t ine for a p p l i c a t i o n . A concentrat ion range between 25 and 100 mg l - 1 i s suggested as being appropriate in the cranberry. PP333 might be of value in new plant ings of cranberry a f ter a desired •mount of canopy has been developed. Condit ions in the cranberry that favour vegeative growth often decrease the development of f lowering upr ights . PP333 might be used to st imulate upright and bud development, while i n h i b i t i n g runner growth. App l ica t ion of PP333 would be less time consuming that runner pruning and damage to uprights would be decreased. Research in to the use of PP333 in apple , cherry , grape, ornamentals and other woody f r u i t crops ind ica te PP333 has much potent ia l use in h o r t i c u l t u r e . CHAPTER 8 SUMMARY 129 PP333 appl ied i s i f o l i a r spray to strawberry p lants grown in a glasshouse decreased vegetat ive growth and y i e l d in a concentrat ion dependent manner. Vegetat ive growth was more responsive to PP333 than f r u i t development, but a delay in f r u i t r ipening was observed, e s p e c i a l l y when PP333 was appl ied at 215 or 1000 mg l " 1 . Runnering was decreased by PP333, but at 215 or 1000 mg 1 _ 1 , leaf development was i n h i b i t e d . PP333 at 46 mg l " 1 decreased runnering without any apparent detr imental e f f e c t s to leaf development or y i e l d . Shoot growth and the shoot i root r a t i o for cranberr ies grown in a glasshouse was decreased by PP333 in a concentrat ion dependent manner. Cranberry p lants t reated with a range of PP333 from 75 to 1200 mg l - 1 set buds under non- induct ive c o n d i t i o n s . A l s o , PP333 increased the number of branches per p lant . PP333 appl ied to f i e l d c ranber r ies at f u l l bloom decreased f r u i t s e t , f r u i t s i z e and y i e l d . PP333 increased bud set for both f lowering or non-f lowering upr igh ts . PP333 appeared to have an e f fec t on bud development that c a r r i e d over in to the fo l lowing growing season. CCC decreased runnering in strawberry, but PP333 was more e f f e c t i v e at lower concent ra t ions . SADH did not have any e f fec t on cranberry , while PP333 e f f e c t i v e l y i n h i b i t e d growth at 75 mg 1 _ 1 , the lowest concentrat ion a p p l i e d . In the strawberry, a p p l i c a t i o n of a high concentrat ion of NPK f e r t i l i z e r st imulated vegetat ive growth and runner ing , but not f r u i t growth. PP333 decreased the promotive e f fec t of NPK on leaf area , but not runner ing. No i n t e r a c t i o n between NPK leve l and PP333 on y i e l d was 130 observed. PP333 t t 46 ug 1 _ 1 d i c r t m d runner production but did not appear to i n h i b i t the promotive e f fec t of the high NPK on leaf development so that the leaf canopy was not det r imenta l ly a f f e c t e d . In the cranberry , both peaty s o i l and high NPK increased shoot number and did not a f fec t bud set of p lants t reated with P P 3 3 3 . However, high NPK decreased f l o r a l i n d u c t i o n . No e f fec t of ni t rogen was observed in the f i e l d cranberry study. Two-dimensional p a r t i t i o n i n g (TDP) provided new information on the e f f e c t s of PP333 and NPK f e r t i l i z e r on strawberry growth and y i e l d . Major cont r ibutors to y i e l d v a r i a t i o n were the adjusted y i e l d va r iab les t russ number, number of r ipe f r u i t , achene number per f r u i t and f r u i t number. Y i e l d was not decreased overa l l by PP333, but decreased in a concentrat ion dependent manner due to a PP333-induced delay in f r u i t r i p e n i n g . In the cranberry , the major cont r ibu tors tD y i e l d v a r i a t i o n were the f r u i t set and f r u i t s i z e . PP333 decreased y i e l d through i t s e f f e c t s on these two y i e l d components. In the cranberry , 6A 3 and AC 94,377 decreased the e f f e c t s of PP333 on shoot e longat ion or bud set but did not have any e f fec t on the decrease in plant dry weight caused by PP333. The rates of NAA appl ied were s l i g h t l y phytotoxic while ABA had no e f f e c t . In the strawberry, po l len germination was decreased by PP333. So i l res idues were a c t i v e 11 weeks a f ter treatement a p p l i c a t i o n . In the cranberry , s o i l res idues of PP333 were ac t ive 50 weeks af ter treatment a p p l i c a t i o n . CHAPTER 9 REFERENCES 1 3 1 Abbott , A . J . , 1968. GroNth of the strawberry plant in r e l a t i o n to ni t rogen and phosphorus n u t r i t i o n . J . H o r t i c . S c i . , 431 491-504. Abbott , A . J . , Best , 6.R. and Webb, R . A . , 1970. The r e l a t i o n of achene number to berry weight in strawberry f r u i t . J . H o r t i c . S c i . , 45i 215-222. Adams, H .N . , 1967. 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D . , Sankhla, N. and Smith, B . N . , 1985. E f fec t of paclobutrazol on the a c t i v i t i e s of some enzymes of ac t iva ted oxygen metabolism and l i p i d peroxidat ion in senescing soybean leaves . J . Plant P h y s i o l . , 121: 453-461 . Voth, V . , P roebs t ing , E . L . , S r . and Br inghurs t , R . S . , 1961. Response of s t rawberr ies to ni trogen in southern C a l i f o r n i a . Proc. Am. Soc. H o r t i c . S c i . , 78: 270-274. Wagner, H. and Michae l , 6 . , 1971. The in f luence of var ied ni trogen supply on the production of cy tok in ins in the roots of sunflower p l a n t s . Biochem. P h y s i o l . P f l anzen , 162: 147. Wahdan, H.A. and Waister , P . D . , 1984. Flower i n i t i a t i o n , f r u i t production and vegetat ive devlopment in non-induced strawberry p lants exposed to outdoor cond i t ions in Scot land . J . H o r t i c . S c i . , 59: 187-196. Wample, R . L . , Schnabel , B and Ahmedullah, M., 1984. Response of f i v e c u l t i v a r s of Vitis v in Hen to pac lobutrazol - a new growth r e g u l a t o r . Hor tScience, 18: 793 ( abs t rac t ) . Wang, S .Y. and S t e f f e n s , 6 . L . , 1985. E f f e c t of paclobutrazol on water s t ress - induced ethylene b iosynthes is and polyamine accumulation in apple seedl ing leaves . Phytochemistry, 24: 2185-2190. 141 Hang, S . Y . , S te f fene , 6 . L . and Faust , M., 1986. E f f e c t of paclobutrazol on c e l l Mall polysacchar ide composition of the apple t ree . Phytochea is t ry , 25: 2493-2496. May, D.M. and Mhite, B . C . , 1968. The in f luence of v igor and ni trogen status on the f r u i t f u l n e s s of Talisman strawberry p l a n t s . J . H o r t i c . S c i . , 43: 409-419. Webster, A .D. and Quin lan , J . D . , 1984. Chemical contro l of tree growth of plum (Prunus dottstict I .) . I . Pre l iminary atudiea with the growth retardant paclobutrazol (PP333). J . H o r t i c . S c i . , 59: 367-375. Wi l l i ams , H.W., 1972. Induction of spur and flower bud formation in young apple t rees with chemical growth re ta rdants . J . Am. Soc. H o r t i c . S c i . , 97: 210-212. Wi l l i ams, H.W., 1984. Use of b ioregulants to control vegetat ive growth of f r u i t t rees and improve f r u i t i n g e f f i c i e n c y . In R.L . Org and F.R. Rutt ige ( E d i t o r s ) , B ioregu lants : chemistry and uses. American Chemical S o c , pp. 93-99, Wi l l i ams, M.W. and S tah ly , E . A . , 1968. E f f e c t of cy tok in ins on apple shoot development from a x i l l a r y buds. Hor tSc ience , 3: 68-69. Winer, B . J . , 1971. S t a t i s t i c a l p r i n c i p l e s in experimental des ign , 2nd e d i t i o n . McGraw-Hi l l , N.Y.,907 pp. Woolley, D . J . and Wareing, P . F . , 1972. The i n t e r a c t i o n between growth promoters in ap ica l dominance. II. Enviromental e f f e c t s on endogenous cy tok in in and g i b b e r e l l i n l e v e l s in Solavuw audi gen a. New P h y t o l o g i s t , 71: 1015-1025. Yas, A.M. and Eaton, B . W . , 1982. E f f e c t of cot ton-grass on the y i e l d components of cranberry . S c i e n t i a H o r t i c , 18: 125-129. Zeevart , J . A . D . , Swanson, C . A . , Fe l lows, R . J . , Ho, L . C , Shannon, J . C and Good, N . E . , 1979. Regulation of a s s i m i l a t e p a r t i t i o n i n g . In P a r t i t i o n i n g of a s s i m i l a t e s , Michigan State U n i v . , pp. 14-17. APPENDIX A  DATA CITED IN CHAPTERS BUT NOT SHOWN TABLE A.I Chapter 3. The e f fec t of f e r t i l i z e r on growth of 'Totee ' and 'Shuksan'strawberry F e r t i l i z e r No. No. Shoot dry Root dry Plant dry treatment crowns leaves wt (g) wt (g) wt (g) Low1 2.1 32 23.0 5.9 28.8 High 2.4 37 27.3 7.4 34.7 S i g n i f i c a n c e • « ##* «*« «» ««« •Low and high f e r t i l i z e r were 45 eg and 160 mg per pot of 20N-B.7P-16.6K of NPK r e s p e c t i v e l y . #« P < 0.01, » * * P < 0.001. TABLE A.11 Chapter 3 . Thi e f f ec t of PP333 on growth of 'Totem' and 'Bhuksan' strawberry Area per Truss Root dry leaf (cm3) length (cm) wt (g) PP333 (eg l" 1 ) Totem Shuksan Totem Shuksan Totem Shuksan 0 65 40 12 10 7.4 6.9 10 59 42 13 12 10.7 6.8 46 ' 59 43 11 9 8.5 5.7 215 46 40 10 10 4.9 5.6 1000 31 37 7 B 4.3 3.7 Control vs . PP333 «#* NS NS PP333 log l inea r *## *#* #** PP333 log quadrat ic *•« NS NS C X contro l vs . PP333 #** NS NS C X PP333 log l i n e a r *«« NS * C X PP333 log quadrtaic * NS NS NPK X PP333 log l inea r NS NS « NS = not s i g n i f i c a n t , or * P < 0.05, #* P < 0.01, ••* P < 0.001. TABLE A . I l l Chapter 6. Shoot a t t r i b u t e s and bud Bet of rooted upr ights and runner cu t t ings of ' M c F a r l i n ' and 'Ben Lear ' cranberry t reated with PP333 and ABA in Experieent 3 Total Bhoot Shoot Bud set PP333 ABA no. length dry wt per (eg I ' M (eg 1-M shoots (ce> (eg) shoot (X) 0 0 4 7 337 2 50 0 4 4 243 29 100 0 5 3 258 43 0 50 4 7 349 4 50 50 5 3 246 24 100 50 5 3 224 21 0 100 5 7 380 2 50 100 5 3 217 2b 100 100 5 4 218 27 ABA trend NS NS NS NS PP333 X ABA NS NS NS NS NS = not s i g n i f i c a n t . TABLE A.IV Chapter 5. The e f fec t of PP333 on ahoot growth of ' M c F a r l i n ' and 'Ben Lear* cranberry Total PP333 No. leaves shoot length (eg l - * ) per plant per plant (ce) 0 444 202 75 447 70 150 3B9 25 300 ' 399 21 600 347 20 1200 273 17 PP333 l inea r »»» «*# PP333 quadrat ic NS #•# C X PP333 l i n e a r NS NS C X PP333 quad. NS NS NS = not s i g n i f i c a n t , or # P < 0.05, * * P < 0 .01, «## P < 0.001. TABLE A.V Chapter 6. The e f fec t of PP333 end f e r t i l i z e r on ihoot growth of ' H c F a r l i n ' and 'Ben Lear ' cranberry Stem dry wt/plant (g) Leaf dry wt/plant (g) PP333 <mg/pot) Low NPK High NPK Low NPK High NPK 0.00 1.29 2.66 0.64 1.52 1.25 0.35 0.64 0.B5 1.46 2.50 0.34 0.53 0.76 1.40 5.00 0.36 0.57 0.67 1.20 PP333 l inear » * * * PP333 quadrat ic * * * NS NPK X PP333 l inear * • * NS NPK X PP333 quadrat ic * * • NS 'Low and high f e r t i l i z e r were 45 mg and 180 mg per pot of 20N-B.7P-16.6K of NPK r e s p e c t i v e l y . NS = not s i g n i f i c a n t , or * * P < 0 .01, #*« P < 0.001. 

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