Open Collections

UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Some effects of cool temperatures on flower production, pollen production and pollen germination in certain… Daubeny, Hugh Alexander 1955

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1955_A4 D2 S6.pdf [ 4.23MB ]
Metadata
JSON: 831-1.0106363.json
JSON-LD: 831-1.0106363-ld.json
RDF/XML (Pretty): 831-1.0106363-rdf.xml
RDF/JSON: 831-1.0106363-rdf.json
Turtle: 831-1.0106363-turtle.txt
N-Triples: 831-1.0106363-rdf-ntriples.txt
Original Record: 831-1.0106363-source.json
Full Text
831-1.0106363-fulltext.txt
Citation
831-1.0106363.ris

Full Text

SOME EFFECTS OF COOL TEMPERATURES ON FLOWER PRODUCTION, POLLEN PRODUCTION AND POLLEN GERMINATION IN CERTAIN LINES OF THE TOMATO (Lycopersicon esculentum. M i l l . ) by HUGH ALEXANDER DAUBENY A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN AGRICULTURE in the Department of Horticulture We accept t h i s thesis as conforming to the standard required from candidates for the degree of MASTER OF SCIENCE IN AGRICULTURE Members of the Di v i s i o n of Plant Science THE UNIVERSITY OF BRITISH COLUMBIA May 1955 ABSTRACT Most commercial tomato v a r i e t i e s require r e l a -t i v e l y high temperatures for f r u i t set and development, and t h i s requirement l i m i t s tomato production i n Canada. There are, however, certain newer v a r i e t i e s which are reported to set f r u i t at cool temperatures (below 55° F.). One such variety, Puck^ a non-commercial type, was con-trasted with the commercial v a r i e t i e s , Bonny Best and 498. Replicated f i e l d and greenhouse experiments were conducted to ascertain the f r u i t setting character of Puck, and cyto-l o g i c a l and h i s t o l o g i c a l studies were done on some aspects of t h i s character. The r e s u l t s are as follows. Puck flowered e a r l i e r and produced more blossoms than the com-mercial v a r i e t i e s and thus had a greater opportunity for f r u i t set at cool, temperatures. Individual Puck blossoms produced more pollen at cool temperatures than did the i n d i v i d u a l blossoms of the commercial v a r i e t i e s . The study on pollen formation i n the d i f f e r e n t l i n e s grown at the cool temperatures showed meiosis to be r e l a t i v e l y normal i n the pollen mother c e l l s , and that pollen degenerated p r i o r to anthesis. A much higher per cent of Puck pollen than Bonny Best pollen was able to germinate at cool temper-atures, and f r u i t set at these temperatures was l a r g e l y parthenocarpic. These r e s u l t s show that Puck has useful c h a r a c t e r i s t i c s which contribute to f r u i t set at cool temper-atures and which can be used i n a plant breeding programme. ACKNOWLEDGEMENT The writer wishes to express his thanks to Dr. C. A* Hornby, Associate Professor of Horticulture and Chairman of the Thesis Committee, for supervision of the experimental work and for valuable assistance i n the preparation of the thesi s . Acknowledgement i s given to the other members of the Thesis Committee; Dr. V. C. Brink, Professor of Agronomy, for his advice i n the preparation of the thes i s ; Dr. K. Cole, Instructor, Department of Biology and Botany, for her help i n the h i s t o l o g i c a l work, and also to Dr. A. F. Barss, Professor Emeritus of Horticulture, Dr. G. H. Harris, Professor of Horticulture, and Dr. F. Dickson, Professor, Department of Biology and Botany. Thanks are also expressed to Mr. J . J. Woods, Superintendent, Saanichton Experimental Station, and Mr. R. M. Adamson, H o r t i c u l t u r i s t at the Station, for t h e i r help and cooperation with the f i e l d experiment. The writer i s indebted to the following organ-izations for f i n a n c i a l assistance during the course of the work: B r i t i s h Columbia E l e c t r i c Railway Company, B r i t i s h Columbia Sugar Refining Company and the Vancouver B'nai B ' r i t h H i l l e l Foundation. i i TABLE OF CONTENTS Page INTRODUCTION 1 LITERATURE REVIEW 3 MATERIALS AND METHODS 14 A. Materials 14 B. Methods . 18 1. Greenhouse experiments 18 (a) 1953-1954 experiment 18 (b) 1954-1955 experiment 20 2. F i e l d experiment 21 3. H i s t o l o g i c a l and c y t o l o g i c a l experiments 23 (a) Meiosis 23 (b) Pollen v i a b i l i t y 25 (c) Pollen production 29 RESULTS 29 1. Greenhouse experiments 29 (a) 1953-1954 experiment 29 (b) 1954-1955 experiment 33 2. F i e l d experiment 39 3. H i s t o l o g i c a l and c y t o l o g i c a l experiments 44 (a) Meiosis 44 (b) Pollen v i a b i l i t y 52 (c) Pollen production ................. 59 DISCUSSION 60 i i i Page SUMMARY AND CONCLUSIONS 71 APPENDIX 73 LITERATURE CITED 81 iv INTRODUCTION There are two main temperature requirements f o r the successful growth, development and f r u i t i n g of a tomato plant i n a commercial planting* These requirements are, f i r s t , a f r o s t - f r e e period greater than three and one-half months, and second, a r e l a t i v e l y warm temperature. In the tomato growing regions of B r i t i s h Columbia the f r o s t - f r e e period i s usually of adequate duration. A l i m i t i n g factor i s the cool temperature existing just a f t e r the plants are set i n the f i e l d i n the spring. Under such conditions the f i r s t truss, and sometimes the second, f a i l to set f r u i t . This lack of early f r u i t set prevents the grower supplying the e a r l i e r and more l u c r a t i v e market, as well as. l i m i t i n g the t o t a l y i e l d possible under the e x i s t i n g conditions. The grower, therefore, would benefit i f f r u i t would set consistently i n cool weather, p a r t i c u l a r l y i n June. It has been reported from several sources (12, 14, 16) that a non-commercial English variety, Puck, could set f r u i t at temperatures too low f o r most commercial var-i e t i e s to do so. The purpose of t h i s investigation was to determine the character or group of characters c o n t r o l l i n g t h i s mechanism with the hope that i t might be transferred to the desirable commercial v a r i e t i e s grown i n Canada. -2-The transfer of t h i s character to commercial var-i e t i e s would be of value for two reasons. F i r s t , i t would increase the early and the t o t a l y i e l d of these v a r i e t i e s i n the areas where they are now grown. Second, i t would extend the area of commercial tomato production i n Canada* Tomato growing would become p r o f i t a b l e i n areas where the temperatures are too cool f o r adequate early f r u i t set i n the existing v a r i e t i e s , p a r t i c u l a r l y areas characterized by warm temperatures i n the l a t t e r part of the growing season. It was necessary to confirm the character of set-t i n g f r u i t at cool temperatures and then determine the mechanisms c o n t r o l l i n g t h i s character. Because fr u i t , set-t i n g i s a result of a complex sequence of developments, only cer t a i n of these developments could be investigated. These studies were l i m i t e d to flower production, pollen production and pollen germination which were believed to be probable l i m i t i n g factors for f r u i t set at cool temperatures. It i s necessary to understand each of these developments, and probably others, i n order to effect recombinations through hybridization to obtain genotypes which w i l l be ac-ceptable as commercial tomato v a r i e t i e s . LITERATURE REVIEW The failure of tomato plants to set f r u i t could be due to a disruption in the normal sequence of f l o r a l development and f r u i t set. The steps involved in this sequence are as follows: 1. Floral induction 2. Floral i n i t i a t i o n 3. Floral development 4. Pollination 5. Fertilization Each step i s affected differently by. the variations in growing conditions. Floral induction and i n i t i a t i o n There are conflicting results reported on the i n -fluence of temperature, nutrient supply, and the amount of light on f l o r a l induction and i n i t i a t i o n in the tomato and related crops. Lewis (26) reported that a temperature of 50° F., compared with temperatures of 77° F. and 86° F., during the period from the expansion of the cotyledons to the appearance of the f i r s t inflorescence gave an increase in flower production. Calvert (10) observed similar re-sults with the variety Ailsa Craig. Went (40), however, stated that low night temperatures, as well as low light intensities, did not materially increase or decrease the - 4 -number of f l o r a l primordia initiated per inflorescence. Initiation, according to Went, is primarily a morphological process influenced by internal organization and genetic constitution, rather than by external factors. Cochran (11), however, observed that higher temperatures resulted in the formation of a greater number of flower buds in pepper, a crop with requirements similar to those of the tomato. White (42) stated that the number of blossom buds formed was lower in nitrogen starved tomato plants, than those re-ceiving adequate nitrogen. According to Howlett (18), f l o r a l primordia were differentiated over a photoperiod of 4 to 24 hours. He obtained no indication that a smaller number of f l o r a l primordia were induced and initiated under a shorter photoperiod. Supplemental illumination, however, for tomato plants grown under a short photoperiod resulted in more buds reaching anthesis. Buds tended to absciss on plants grown without the extra illumination.' Floral development The development of a tomato flower can be consid-ered in three stages: (a) Development of the perianth (b) Development of the stamens (c) Development of the p i s t i l (a) Development of the perianth Z i e l i n s k i (44) described f a s c i a t i o n i n the p e r i -anth of the tomato flower. This phenomenon was the r e s u l t of unfavourable environmental conditions, such as r e l a t i v e l y low temperatures of 45° F. to 55° F., high nitrogen l e v e l , low l i g h t i n t e n s i t y , and prolonged drought followed by abundant moisture, int e r a c t i n g with certain genotypes. Sepals may or may not be present i n fasciated flowers and, i f present, exist i n numbers as high as eighty. Such sepals often become p e t a l - l i k e . Petals also can be absent or can occur i n exaggerated numbers. Both the petals and sepals can be present i n more than one whorl. (b) Development of the stamens Unfavourable environmental factors i n t e r a c t i n g with diff e r e n t genotypes cause abnormal stamen development. For instance, Howlett (17) found that a carbohydrate d e f i -ciency resulted i n male s t e r i l i t y . In some cases he ob-served that the procession of the chromosomes at meiotic anaphase was i r r e g u l a r and the two homologous groups f a i l e d to separate completely. In most cases buds from carbohy-drate def i c i e n t plants showed normal meiosis with microspore tetrads degenerating a f t e r the second telophase. In n i t r o -gen deficient plants there was much less male s t e r i l i t y than - 6 -in carbohydrate deficient plants. According to Judkins (20), pollen exhibited a lower v i a b i l i t y during periods of low light intensities. Lesley and Lesley (25) claimed that pollen abortion could also occur from the effect of high temperature. Schneck (36) compared English with American var-ieties and found in the former more viable pollen was con-sistently produced and less was required for f e r t i l i z a t i o n since fewer seeds were produced. Fasciation, described by Zielinski (44), also af-fects the stamens, and often results in adhesion of stamens to the corolla or calyx and cohesion of the antheridial f i l a -ments. Rudimentary anther sacs with aborted pollen are also a common result of fasciation. Several gene mutations influence normal pollen development. Lesley and Lesley (25) described a mutant where many of the pollen mother cells degenerated before meiosis. Those pollen mother cells which did not degener-ate showed abnormalities in meiosis that resulted in an un-even distribution of chromosomes and consequently complete pollen s t e r i l i t y . Rick (33) discovered two mutants where pollen mother cells degenerated prior to mid-prophase of meiosis. In one of these the development of the sporogen-ous tissue was largely impaired in premeiotic stages, while in the other, degeneration occurred sometimes in the early p rophase . Soost (39) r e p o r t e d on f i v e mutants , each o f which showed s t e r i l i t y due to one o f f i v e n o n - a l l e l i c a s y n a p t i c genes . In a s tudy o f two o f these he found p a i r i n g to be v a r i a b l e i n the prophase stage o f pachytene and d i a k i n e s i s and i n the metaphase s t a g e . The r e s u l t i n g u n i v a l e n t s underwent i r r e g u l a r d i s t r i b u t i o n a t the anaphase o f both the f i r s t and second d i v i s i o n s . T h i s r e s u l t e d i n the f o rma t i on o f m i c r o n u c l e i and abo r t ed p o l l e n . Soost (39) thought the a c t i o n of these a s y n a p t i c genes i n the tomato cou ld be i n f l u e n c e d c o n s i d e r a b l y by t empera tu re . A t a r e l a t i v e l y h i g h temperature o f 92° F. the genes exe r t ed a maximum e x p r e s s i o n . The author s t a t e d t h a t t h i s c o n c l u -s i o n was open to c r i t i c i s m because i t was d i f f i c u l t to e s t a b l i s h the t ime r e l a t i o n s h i p s i n v o l v e d i n the m e i o t i c p rocess and t h e r e f o r e maximum e x p r e s s i o n o f the gene might have r e s u l t e d from the e f f e c t s o f low temperature p r e c e d i n g the h i ghe r t empera tu re , s i n c e tempera tures i n the greenhouse were not u n i f o r m . In some mutants , m e i o s i s proceeded n o r -m a l l y but the p o l l e n degenerated b e f o r e m a t u r i t y . R i ck (33) found a mutant where the m i c rospo res degenerated s h o r t l y a f t e r f o rma t i on o f m i c rospo re t e t r a d s . L e s l e y and L e s l e y (24) d i s c o v e r e d another mutant where p o l l e n development was a r r e s t e d j u s t p r i o r to a n t h e s i s . -8-Pollen can be produced normally, but may not be released from the anthers due to morphological abnormali-t i e s . One such example i s the mutant described by Larson and Paur (21) where the connate form of the petals resulted i n considerable c o n s t r i c t i o n of the anthers and tended to hold them i n close contact with the p i s t i l and thus pre-vented rupture of the stromium and the subsequent release of the pollen. Leopold and Scott (23) used a morphological s e l f - s t e r i l e s t r a i n of the John Baer v a r i e t y . The stamens i n t h i s s t r a i n c h a r a c t e r i s t i c a l l y developed a brown rin g of necrotic tissue at the a n t h e r i d i a l t i p s which e f f e c t i v e l y prevented any pollen from reaching the stigmatic surface. (c) Development of the p i s t i l Unfavourable environmental fa c t o r s , i n t e r a c t i n g with d i f f e r e n t genotypes, can cause abnormal p i s t i l develop-ment i n the tomato flower. Rick (34) described two types of female s t e r i l i t y i n the tomato due to n u t r i t i o n a l fac-t o r s . In the f i r s t type, the megaspores degenerated im-mediately a f t e r meiosis. In the second type, an embryo sac mother c e l l was not formed and the nucellus remained undif-ferentiated. Rick attributed these conditions to a lowering of the nutrient l e v e l within the plant since the proportion of s t e r i l e ovules usually decreased as conditions became more - 9 -f a v o u r a b l e . S i m i l a r l y , Howlett (17) found t h a t severe n i t r o g e n d e f i c i e n c y r e s u l t e d i n female s t e r i l i t y . Environmental f a c t o r s markedly i n f l u e n c e s t y l a r development. Burk (9) reported t h a t a short photoperiod and a low l i g h t i n t e n s i t y r e s u l t e d i n s t y l a r e l o n g a t i o n before anther dehiscence. Howlett (18) found that an ex-c e s s i v e amount of carbohydrates a l s o caused s t y l a r elonga-t i o n . According to Smith (37)» the i n t e r a c t i o n of high temperature w i t h low humidity c o n t r i b u t e d to s t y l a r e l o n -g a t i o n . A number of workers (5, 9, 18) have described two types of s t y l a r development i n tomatoes. The f i r s t type i n c l u d e s those, which under adverse c o n d i t i o n s , show elonga-t i o n of the s t y l e above the a n t h e r i d i a l . cone. This condi-t i o n prevents s e l f - p o l l i n a t i o n . The second type does not show t h i s e longation and thus i s s e l f - p o l l i n a t e d . Howlett (18) c l a s s i f i e d most of the American v a r i e t i e s i n t o the f i r s t group and most of the E n g l i s h v a r i e t i e s i n t o the second group. Of the known causes of u n f r u i t f u l n e s s i n the tomato, s t y l a r elongation i s the most d i f f i c u l t to e x p l a i n . Johnson and H a l l (19) p o s t u l a t e d t h a t under high l i g h t i n -t e n s i t i e s e longation was due to an excessive production of the auxin, i n d o l - a c e t i c a c i d , since the high i n t e n s i t y des-troyed i t s enzyme i n a c t i v a t o r , i n d o l - a c e t i c - o x i d a s e . Under -10-low l i g h t i n t e n s i t i e s the excessive auxin was thought to be due to a lack of synthesis of the i n a c t i v a t o r . The p i s t i l , as was the case with the other f l o r a l parts of the tomato, can become fasciated (44)• The re-sults of t h i s f a s c i a t i o n are p a r t i a l to complete d i s t o r t i o n of the p i s t i l l a t e parts. In the ovary of fasciated flowers the locules often are increased i n number and the ovules become aborted and rudimentary. Sometimes up to seven p i s -t i l s are formed i n a single flower, and frequently at l e a s t one of these p i s t i l s i s f u n c t i o n a l . The f r u i t s set by fasciat;ed . flowers are usually highly i r r e g u l a r i n form. Poll inat ion Germination of pollen and growth of the pollen tubes down the s t y l a r t i s s u e are influenced by environmental f a c t o r s . Smith (37) reported that the maximum growth rate of tomato pollen tubes occurred at 70° F., with 85° F. 50° F., and 100° F» giving progressively decreased rates. Per-centage of pollen germination was found to be very poor at 100° F. and only f a i r at 50° F. Even under the optimum temperature conditions of 70° F., according to Smith, pollen tube growth was slow with only one twenty-fifth of the s t y l a r length being traversed i n twenty-four hours. This slow growth rate increased the chances of the stigma, s t y l e , - l i -ana pollen being destroyed by unfavourable conditions. Judkins (20) presented data which conflicted with that of Smith's. He stated that, at a temperature of 70° F., an appreciable number of pollen tubes had penetrated to the ovary at the end of twenty-four hours. Bonn (2) found, with a limited amount of experi-mental work, that the pollen produced by a late line did not give f r u i t set under a daily minimum temperature of 54° F. to 59° F. and a daily maximum temperature of 63.5° F. to 66.5° F. In contrast to this, the pollen produced in an early line did give f r u i t set under similar conditions. He concluded that the c r i t i c a l temperature, differentiating pollen germination, tube growth and/or f e r t i l i z a t i o n in these two tomato lines, occurred between 55° F. and 65° F. Fer t i l i z a t i o n Smith (37) reported that f e r t i l i z a t i o n occurred between 82 and 94 hours after pollination at a temperature between 60° F. and 75° F. Richardson and Currence (32), however, claimed without giving temperature conditions, that a period of 24 hours was required for pollen to germin-ate, grow through the style, and f e r t i l i z e sufficient ovules to produce some seed and f r u i t . Leopold and Scott (23) said that the failure of undeveloped, unabscissed flowers to set f r u i t and grow, - 1 2 -despite p o l l i n a t i o n or the use of a f r u i t - s e t t i n g agent, was due to a l i m i t a t i o n i n organic nutrient material* Such flowers often occur on clusters which have already set sev-e r a l f r u i t . They also claimed that the ovaries, as well as the s t y l e s , pollen v i a b i l i t y and pollen tube growth, were sensit i v e to temperature. Furthermore, they concluded that the capacity of a tomato ovary to set f r u i t was strongly dependent upon the mature leaves on the plant. They postu-lated that t h i s dependence may explain the lack of f r u i t set on the f i r s t and second flower c l u s t e r s , when the leaf number i s low, as i s the case i n the f i e l d at time of transplanting. Nitsch ( 2 9 ) claimed that most v a r i e t i e s of toma-toes w i l l produce parthenocarpic f r u i t s at a r e l a t i v e l y low temperature, but not at a high temperature. Osborne and Went ( 3 0 ) also found parthenocarpic f r u i t at a low temperature, with a high l i g h t i n t e n s i t y . Lesley and Les-ley ( 2 5 ) , however, reported that parthenocarpic f r u i t was formed at a comparatively high temperature and a long photoperiod. It appears, therefore, that parthenocarpic f r u i t s are induced under a number of conditions on either side of the optimum. There are a number of reports on the i n t e r a c t i o n of environment and genotype on f r u i t set, without elabora-t i o n as to what s p e c i f i c f l o r a l mechanisms are involved* -13-Went (40) reported that the minimum night temperature f o r f r u i t set i n tomatoes was 59° F. There must be, however, considerable v a r i e t a l response to minimum and optimum night temperatures because Learner and Wittwer (22) found that 70° F. was the optimum temperature f o r f r u i t setting and f r u i t growth i n the v a r i e t i e s John Baer and Rutgers, compared to 60° F. f o r the va r i e t y Early Chatham. The l a s t named yielded an appreciable number of f r u i t at night temperature below 60° F. and produced some f r u i t at a minimum night tempera-ture 40° F. Went and Cosper (41) observed Earliana 498 to set appreciable f r u i t at a night temperature of 56° F,, i n contrast to the Beefsteak and Stone v a r i e t i e s . They also reported that day temperature modified only s l i g h t l y , the response to night temperature. They noted that there was a marked c o r r e l a t i o n , e s p e c i a l l y i n Beefsteak and Stone, i n y i e l d of ripe f r u i t with a high minimal temperature of at least 56° F. one month before ripening. This time co-incides with the period of f r u i t set. Obviously there are many factors which can i n t e r -act to prevent f r u i t set i n tomatoes grown at lower temper-atures. -14-MATERIALS AND METHODS A. Materials This study, as outlined already, was intended to ascertain the reason for some tomato lines setting f r u i t at temperatures lower than those required by most common var-ie t i e s . The following varieties were used in the experi-ments. Puck Puck was introduced in England in 1948 by M . B. Crane (12) who described i t as a dwarf bush variety that produced an early and a heavy crop. Heydecker (16) stated that Puck had a main stem and side shoots sturdy enough to keep the fruit off the ground. (Dwarf types are like stan-dard types in producing three leaves between each truss, but differ from them by their much shorter habit, thicker dark green leaves and thicker stems capable of standing unsupported until fruiting time. Bush types, on the other hand, produce less than three leaves between each truss and have a more spreading, less upright growth habit than do the dwarf types). Heydecker described the f r u i t of Puck as medium in size and possessing the uniform colour gene. He thought that the self-restricting growth habit, with a -15-l i m i t e d number of a x i l l a r y branches contributed to very early cropping and that i n England Puck appeared to be i d e a l for cloche gardening because the plants could be grown under cloches u n t i l the harvesting of the very early crop. In the United States, F r a z i e r (14) described the va r i e t y as one with the unusual c h a r a c t e r i s t i c of setting f r u i t at a temperature below 55° F. when grown i n the Wil-lamette Valley i n Oregon. Puck was thus chosen as a pos-s i b l e source of tolerance to low temperatures. The parentage of Puck was complex. This v a r i e t y was a selection from the F2 of a cross between V i c t o r , an American bush type, and F i r s t - i n - t h e - F i e l d , a dwarf type (6). Victor originated from a cross between A l l r e d and Break 0' Day and was described by Yeager (43) as a v a r i e t y with the f i r s t f r u i t ripening at the same time as that of Earliana and outyielding Earliana during the f i r s t few weeks of early production. F i r s t - i n - t h e - F i e l d was described by Brown (6) as a dwarf var i e t y of unknown o r i g i n introduced i n England i n 1944. The v a r i e t y appeared to be synonymous with L i l l i p u t , Premier, Q77 arid very similar to a Russian introduction, Stambovoi Alpapsv. A l l these possess the typ-i c a l c h a r a c t e r i s t i c s of dwarf types, three'leaves between each inflorescence, small size of plant with stout stems and thick, dark green leaves. Puck was selected to combine -16-the stout stem of the dwarf type with the bush type charac-t e r . The f i r s t s e l e ction was made i n the F 2 and the only further selection was for y i e l d . Bonny Best Puck was compared to Bonny Best, a popular second early variety which has been used extensively i n past i n -vestigations. Boswell ( 3 ) stated that the time required for maturation of Bonny Best f r u i t was lengthened consider-ably under cool or other unfavourable conditions. Typically, there are four or f i v e flowers per c l u s t e r , with two or three f r u i t s being set per c l u s t e r . Because Bonny Best has been used i n previous work, the v a r i e t y was included i n these experiments to enable comparison with e a r l i e r work. Earliana Earliana i s one of the e a r l i e s t important tomato v a r i e t i e s grown i n B r i t i s h Columbia. The number of flowers per cluster i s seven to nine with normally three or four f r u i t s being set per cluster ( 3 ) . This va r i e t y can be re-garded as the popular early commercial tomato v a r i e t y and thus was chosen for comparison with Puck. The s t r a i n of Earliana used i n t h i s work was Morse's Special 498 and w i l l subsequently be referred to as 4 9 8 . -17-Gem Gem, a new variety, was described as producing a small and compact plant of determinate growth habit and thus s u i t a b i l i t y for close planting ( l ) . Recent verbal reports from the Okanagan Valley suggested that Gem could set f r u i t during periods of cool temperature; therefore, i t was chosen fo r comparison with Puck, as well as for a possible a d d i t i o n a l source of the f r u i t setting character at cool temperatures. Ear l y Chatham Early Chatham i s a very early bush type, which i s grown f a i r l y extensively i n B r i t i s h Columbia i n home gardens. Bowser (4) described the f r u i t as e a r l i e r ripening than that of both Victor and 498. This v a r i e t y was included i n t h i s study because of i t s reputed e a r l i n e s s . Puck x 498 and 498 x Puck These r e c i p r o c a l crosses, made i n the summer of 1953 at The University of B r i t i s h Columbia were studied to secure some knowledge of the pattern of inheritance of the alleged f r u i t setting character i n Puck. They were also an attempt to combine the earliness of 498 with the f r u i t setting character of Puck. -18-B. Methods The investigations included greenhouse and f i e l d experiments. 1. Greenhouse experiments (a) 1953-1954 experiment The f i r s t experiment was done in the greenhouse during the winter of 1953-1954 to compare the fru i t setting a b i l i t y of Puck and Bonny Best as affected by contrasting a relatively cool temperature with the more optimum range for tomatoes. The temperature in both the warm and the cool greenhouse was recorded by thermographs. Temperatures be-tween 50° and 55° F. in the cool house and between 65° and 70° F. in the warm house were maintained as closely as possible. The benches in each house were along the outside wall of the respective houses. The plants were grown in a randomized block experiment with four replications in each house. The blocks consisted of two plots with three plants in each plot. The plants were l | feet apart in plots and 1 foot apart in parallel rows. Each block was a single row, thus giving an arrangement which would sample any var i a b i l i t y which might have existed due to the plants being grown adjacent to the glass. - 1 9 -Seeds of Bonny Best and Puck were sown on Nov-ember 2, 1953. The seedlings were pricked o f f i n f l a t s on November 2 4 t h . A l l plants at these stages were kept under the warm temperature condition. On December l S t h , the plants were placed under the d i f f e r e n t i a l temperature con-d i t i o n s . On January 4, 1954, two plants of Puck and one plant of Bonny Best were replaced i n the warm house, and two plants of Puck and one Plant of Bonny Best i n the cool house. Each bench was then watered with one gallon of Chesthunt compound to control damping-off organisms. From March 10th u n t i l A p r i l 22nd, a l l plants i n the plots i n the cool house were hand-pollinated with pollen produced under the warmer temperature. P o l l i n a t i o n s were done every t h i r d or fourth day during t h i s period. On March 22nd, a f t e r a period of sunny weather, an examination of flowers for abnormalities on the second truss of the plants was made. In the cool house every plant i n the bench was examined for abnormalities, whereas i n the warm house only plants i n two of the four blocks were examined, because a l l plants were exhibiting normal flowers. At the beginning of May, the following data were taken: 1. Total f r u i t set on a l l plots i n the warm and the cool temperature. -20-2. Pollen production and s t y l a r elongation for ten flowers from each plot i n the cool temperature. 3. F r u i t set was recorded on twelve plants each of the two v a r i e t i e s , Puck and Bonny Best, previously used for h i s t o l -o g i c a l studies. These plants were suitable, since no f r u i t set for a period of one month p r i o r to May 1st had been removed. (b) 1954-1955 experiment A second experiment i n the greenhouse was carried out during the winter of 1954-1955. At t h i s time, for both Puck and Bonny Best grown at the cool temperature, the ef-fects of hand-pollination, with pollen produced at the warm temperature were compared to no p o l l i n a t i o n . The plot arrangement for t h i s experiment was the same as i n 1953-1954. Treatments were designated as follows: (1) Warm temperature, with no hand p o l l i n a t i o n s . (2) Cool temperature, with no hand p o l l i n a t i o n s . (3) Cool temperature with hand p o l l i n a t i o n s , using pollen produced at the warm temperature. Seeds of Puck and Bonny Best were sown on Septem-ber 28th and pricked o f f on October 19th. U n t i l the time of transplanting the seedlings were grown at the warm temper-ature. Plants of each var i e t y were placed i n the benches under the respective temperature conditions on November 11th. - 2 1 -In the warm house part of an extra bench was used for s i x plants of Puck and six plants of Bonny Best to be used as pollen sources. A l l plot plants, with the exception of those of Puck, were pruned to a single stem. At f i v e day i n t e r v a l s the number of blossoms and the number of f r u i t set were recorded for each plot at both temperature conditions. The f i r s t data i n the warm house were taken December 1 1 t h ; while the f i r s t data i n the cool house were taken February 1, 1 9 5 5 . The l a s t complete blos-som and f r u i t set count was made on February 2 1 s t i n the warm house and on May 1 s t i n the cool house. In the cool house the f i r s t hand p o l l i n a t i o n s , using pollen produced under warm temperature conditions were done on February 9 t h . Subsequently, hand p o l l i n a t i o n s were done every fourth day, u n t i l March 6 t h , a f t e r which date they were done every second day. The l a s t hand p o l l i n -ations were done on A p r i l 1 9 t h . A l l plants were shaken every day to dislodge the pollen. At the cool temperature, on May 2 n d , ten f r u i t s of each variety from each treatment were selected and ex-amined for seed. A l l f r u i t selected was mature green or f u l l y r i p e . 2• F i e l d experiment Three v a r i e t i e s of tomato plus the F i r e c i p r o c a l crosses of two of these v a r i e t i e s were used, namely; 1 . Puck -22-2. 498,3. Puck x 498,4. 498 x Puck, 5* Bonny Best. The f i e l d experiment was located at the Experi-mental Station, Saanichton, British Columbia* The s o i l was a sandy loam. The plants were set out in a Latin Square design, with five replications, giving a total of 25 plots in five blocks and five rows. Between each plot, within a row, there was a check plant of Puck. A. guard row was used around the entire experiment. The seed was sown A p r i l 1, 1954. The plants were pricked off in fla t s after two weeks. The f l a t s were l e f t in the greenhouse u n t i l a few days prior to transplanting, when they were moved to a cold frame. Field planting was done on May 16th. Plants of Bonny Best, 498, and the re-ciprocal crosses were pruned and trained to a single stem* Puck plants were not pruned. Beginning on June 1st, when the f i r s t flower at anthesis was noted on a plot plant, a count of the number of flowers at anthesis and the number of fr u i t set in each plot was made every five days. From July 12th u n t i l July 31st this count was made at seven day intervals. After July 31st one count of f r u i t set per plot was made on Aug-ust 21st and the number of ripe f r u i t per plot recorded u n t i l September 11th. A l l counts were for the f i r s t four trusses only. A complete record of temperature conditions on the station was obtained for the period from May 15, 1954 to September 11, 1954. - 2 3 -3* Histological and cytological experiments During the winter of 1954-1955 cytological stud-ies were done on seven different lines of tomatoes, namely; 1. Puck, 2. 498, 3 . Puck x 498, 4. 498 x Puck, 5. Bonny Best, 6. Early Chatham, and 7* Gem. Plants for these stud-ies had been raised (a) from cuttings taken from the f i e l d September 18, 1954, rooted in sand and potted up October 8th and (b) from seeds of a l l lines, except 498 x Puck, sown September 28th and pricked off October 19th. The seedlings were potted up November 11th. At this time an equal distribution of plants from each line was made to each temperature condition. One plant of each line raised from seed was planted in additional bench space in the cool house. (a) Meiosis The meiotic process in a l l the varieties was stud-ied at the two temperature conditions. Pollen smears were made using acetocarmine to stain the chromosomes. At f i r s t the method reported by Brown (7) was used to make the pollen mother c e l l smears. Since this procedure did not stain clearly, modifications were made, and the following technique was found to be the most satisfactory. -24-1. Buds were k i l l e d and fixed for two hours in a solution of three parts ethyl alcohol to one part acetic acid. 2. Buds were stored in 70 per cent alcohol u n t i l used. 3. Buds were washed in d i s t i l l e d water for 15 minutes. 4. Anthers were removed from bud in a drop of d i s t i l l e d water on a slide. Bud debris was removed and d i s t i l l e d water was taken up with a blotter. 5* Anthers were dissected in a drop of acetocarmine on slides. The acetocarmine contained iron rust. 6. Cover slips were placed and then pressed onto the dis-sected anthers. 7. Slides were then heated gently. 8. Slides were sealed temporarily with na i l polish. Semi-permanent preparations were sealed with gum mastic. Preliminary work was done to determine the size of bud that would show meiosis in the different varieties at the two temperature conditions. In smears that showed meiosis proceeding, 40 to 60 pollen mother ce l l s , chosen at random, were observed. The stage of division and abnormalities, i f any, were re-corded for each c e l l examined. Altogether approximately 200 slides were prepared. Camera lucida drawings were made of the more commonly occurring irregularities. - 2 5 -(b) Pollen v i a b i l i t y Acetocarmine and iodine-potassium iodide solu-t i o n were each used to ascertain percentages of viable and non-viable or aborted po l l e n . Acetocarmine was used as described f o r studying meiosis, except that a l l anther debris was removed, because at t h i s stage the pollen was completely free within the anthers. A preliminary pro-cedure, similar to that used with acetocarmine,was used with the iodine solution. For both the acetocarmine and the iodine t e s t s , flowers at anthesis were used. In each flower examined, three samples,of 1 0 0 pollen grains each, were drawn at ran-dom and observed. Pollen i n these samples was c l a s s i f i e d as 1. viable, 2. intermediate or doubtful and 3 . non-viable or aborted. In the cool house flowers were taken f o r each variety from both the potted plants and the special plants i n the bench. Due to v a r i a b i l i t y i n counts from these mixed samples, flowers from each var i e t y were l a t e r separ-ated as to whether they were from plants that were growing i n the pots, or else from plants growing i n the bench. Only a few counts were made i n the warm house, since r e s u l t s were consistent, with a l l v a r i e t i e s producing over 96 per cent viable pollen. On A p r i l 13th ten flowers of Puck and ten -26-flowers of Bonny Best at anthesis were taken from plot plants i n the cool house and examined for percentage of viable pollen grains. This procedure was repeated on A p r i l 13th. During the. .winter of 1953-1954, comparisons were made of pollen germination and pollen tube growth i n Puck and Bonny Best grown at the two temperatures. A l l pollen used was produced i n the warm house. For t h i s study 50 plants each of both v a r i e t i e s were potted.up on December 18th and subsequently grown at the warm temperature and subjected to a 12-hour l i g h t period. On February 4th, one-half of the plants of each v a r i e t y were placed i n the cool temperature house under a 12-hour l i g h t period. The procedure for the p o l l i n a t i o n s was a follows. 1. Flowers were emasculated before the petals were reflexed and t h i s operation was done with a pair of tweezers, so that the anthers, petals, and sepals were removed as a cone. 2. Pollen was transferred on the f l a t t i p of a pair of tweezers to the stigmatic surfaces of the emasculated flowers. (Puck pollen produced at the warm temperature was used to p o l l i n a t e Puck stigmatic surfaces on plants at both tempera-tures). Bonny Best p o l l i n a t i o n s were done s i m i l a r l y . 3« The po l l i n a t e d flowers were now is o l a t e d with a size 00 or a size 0 g e l a t i n capsule. -27-4. Following a period of 24 hours, the po l l i n a t e d stigmas and t h e i r s t y l a r columns were removed and placed i n a v i a l containing a drop of water. The styles were dissected, stained and mounted following a modification of Buckholtz's (&) procedure: 1. The styles were severed at the ovary and within 15 minutes a f t e r removal from the plant were dissected along one side with a fine sewing needle and placed i n b o i l i n g water for two minutes. 2. The styles were next placed i n a k i l l i n g and f i x i n g solution consisting of 96 cc. of 50 per cent alcohol and 4 cc. of 6 per cent formalin with a drop of safranin added. 3. After a period of at least two hours i n the k i l l i n g and f i x i n g solution, the styles were washed i n running water for an hour. 4. The styles were next placed on a glass s l i d e and some of the c o r t i c a l tissue removed by scraping with a needle. 5. The styles were now placed i n the stain for three minute The stain was prepared by mixing eight parts of 1 per cent aqueous acid fuschin and two parts of 1 per cent aqueous l i g h t green. This reagent stained the tissues very darkly and d i f f e r e n t i a t i o n was poor. For l a t e r work the stain was -28-d i l u t e d to four parts of water to one part of stai n and the tissues were more e a s i l y d i f f e r e n t i a t e d because they were not so dark. 6. Next the tissues were destained i n 80 per cent l a c t i c a cid u n t i l no more stai n came out, which usually required a period of ten minutes. 7 . The stained styles were then placed i n 85 per cent l a c t i c acid p r i o r to mounting. 8 . The styles were mounted on a glass s l i d e i n 85 per cent l a c t i c a c i d . A f t e r pressure was applied to the cover s l i p i t was sealed with gum arable i n x y l o l . 9 . The mounted styles were l e f t to clear for 24 hours p r i o r to examination. A count of the number of both germinated pollen grains and non-germinated grains was made for each stigmatic surface. Also an attempt was made to trace pollen tube growth down the s t y l a r tissue and to measure the lengths of the tubes. Pollen germination studies were made during the winter of 1954-1955 using an acetocarmine s t a i n to d i f f e r -entiate between germinated and non-germinated grains. The procedure was the same as that used with a l l the aceto-carmine work. - 2 9 -(c) Pollen production Macroexaminations for pollen production at both temperatures on plants for the c y t o l o g i c a l studies were made every f i f t h day beginning November 12, 1954. Equal numbers of plants of each v a r i e t y were used for t h i s study. Five blossoms at anthesis were taken from each var i e t y at the two d i f f e r e n t temperature conditions and examined for pollen by scraping the inner surface of the anthers with a needle. Any white powdery material on the needle was i n -dica t i v e of pol l e n . At the cool temperature i t was not always possible to get f i v e blossoms from each v a r i e t y at anthesis at one timej therefore, only the number at anthesis could be examined. R E S U L T S 1. Greenhouse experiments (a) 1953-1954 experiment Observations made on March 22nd of the flowers on the second truss of the plants of Bonny Best and Puck growing i n the benches i n the cool house showed that a larger per cent of Bonny Best flowers were abnormal than was the case for Puck flowers. The 36 flowers of Bonny Best at anthesis were c l a s s i f i e d into the following categories: - 3 0 -1. Flower:: normal, st y l e not elongated, s l i g h t f a s c i a t i o n , 41.7 per cent. 2. Flower abnormal, style elongated, some f a s c i a t i o n and increase i n number of f l o r a l parts, 36.1 per cent. 3« Flower abnormal, st y l e elongatedj anthers aborted, some f a s c i a t i o n , 13.9 per cent. 4« Flower abnormal, style elongated, anthers aborted, petals aborted, 5»5 per cent. 5. Flower abnormal, st y l e elongated, gross f a s c i a t i o n of a l l parts, 2.7 per cent. There were 107 flowers of Puck at anthesis. Only f i v e of these were abnormal with three of these occurring on one plant and showing s l i g h t l y elongated st y l e s and reflexed petals, a condition which would most l i k e l y prevent s e l f -p o l l i n a t i o n . The other two flowers were fas c i a t e d . In contrast to Bonny Best, where 2.7 per cent of the flowers examined showed pollen, 39»2 per cent of the Puck flowers did so. Seven f r u i t s were counted on the second trusses of Bonny Best plants and eleven f r u i t s on the second trus-ses of Puck plants. In Table 1, i t i s seen that 85 per cent of the Fuck flowers examined at the cool temperature showed some pollen, whereas only 25 per cent of the Bonny Best flowers did. The plants which had been previously used i n h i s t o l -o g i c a l work showed 6 f r u i t set on Bonny Best compared to 35 set on Puck. -31- c Table 1. Pollen production and stigmatic surface position i n 40 flowers each of Puck and Bonny Best, grown at the cool temperature Puck Bonny Best Pollen abundant Stigmatic surface beneath a n t h e r i d i a l cone 33 0 Stigmatic surface at a n t h e r i d i a l cone 0 0 Stigmatic surface above a n t h e r i d i a l cone 0 0 Pollen scarce Stigmatic surface beneath a n t h e r i d i a l cone 1 10 Stigmatic surface at a n t h e r i d i a l cone 0 0 Stigmatic surface above a n t h e r i d i a l cone 0 0 Pollen n i l Stigmatic surface beneath a n t h e r i d i a l cone 6 22 Stigmatic surface at a n t h e r i d i a l cone 0 2 Stigmatic surface above a n t h e r i d i a l cone 0 6 It i s shown by inspection of data i n Tables 2 and 3 that both Puck and Bonny Best set more f r u i t at the warm temperature than at the cool temperature. Table 2. Number of f r u i t set on Puck and Bonny Best grown at the cool temperature Puck Bonny Best Total Block 1 53 35 88 Block 2 60 3 0 9 0 Block 3 63 37 100 Block 4 52 38 9 0 Total 228 140 368 Analysis of variance -Source S.S. D.F. Mean Square F Required F Total 1092 7 5% 1% Variety 9 6 8 1 9 6 8 3 6 . 2 9 10.13 34.12 Block 44 3 14.67 Error 80 3 26.67 L.S.D. between varie t y t o t a l s at odds of 1 9 : 1 i s 46.46 L.S.D. between variety t o t a l s at odds of 9 9:1' i s 85.32. -32-In Table 2, i t i s seen that Puck set more f r u i t at the cool temperature than Bonny Best and the difference was highly s i g n i f i c a n t . Because hand p o l l i n a t i o n s were done at the cool temperature i n both v a r i e t i e s , i t i s not possible to determine from these data whether Puck would have set more f r u i t than Bonny Best had no pollen been ap-p l i e d to the stigmas. Table 3. Numbers of f r u i t on Puck and Bonny Best grown at the warm temperature Puck Bonny Best Total Block 1 88 52 140 Block 2 124 64 188 Block 3 63 76 139 Block 4 96 66 162 Total 371 258 629 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 3,781.88 7 - 5% 1% Variety 1,596.13 1 1,596.13 3.43 10.13 34.12 Block 790.13 3 263.38 Error 1,395.62 3 465.21 L.S.D. between v a r i e t y t o t a l s at odds of 19:1 i s 194.01 L.S.D. between v a r i e t y t o t a l s at odds of 99:1 i s 356.30. In Table 3 i s i s shown that there were no s i g n i f i -cant differences between the two v a r i e t i e s i n the amount of f r u i t set at the warm temperature. -33-(b) 1954-1955 experiment The effect of temperature on the number of flower buds induced and i n i t i a t e d i n both v a r i e t i e s i s shown i n Tables 4 and 5 for cool and warm temperatures respectively. Table 4. Number of flower buds formed on f i r s t four trusses of Puck and Bonny Best grown at the cool temperature Truss 1 Truss 2 Truss 3 Truss 4 Total Puck Block 1 46 30 32 34 142 Block 2 35 42 40 34 151 Block 3 40 40 27 36 143 Block 4 40 37 37 41 155 Total 161 149 136 145 591 Bonny Best Block 1 19 27 17 25 88 Block 2 25 22 22 43 112 Block 3 23 25 26 42 116 Block 4 19 23 36 36 114 Total £6 97 101 146 430 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 2,130.72 31 5% .1% Variety 810.03 1 810.03 6.32 10.13 34.12 Truss 220.59 3 73.53 Block 112.59 3 37.53 Varietyx Truss 384.35 3 128.12 3-38 3.86 6.99 V a r i e t y x B l o c k 45.85 3 15.28 3.86 6.99 Truss x Block 216.04 9 24.04 Error 341.27 9 37.92 L.S.D. between var i e t y x truss t o t a l s at odds of 19:1 i s 45.63 L.S.D. between var i e t y x truss t o t a l s at odds of 99:1 i s 56.60 / -34-In comparing the two v a r i e t i e s grown at the cool temperature, there were no s i g n i f i c a n t differences among fourth trusses and the differences among t h i r d trusses, although greater, were s t i l l not s i g n i f i c a n t ; whereas the differences among second trusses were s i g n i f i c a n t , and f o r f i r s t trusses were highly s i g n i f i c a n t i n favour of Puck. If the mean square of the error had been used as the t e s t -ing term, .the differences between the v a r i e t i e s would have been s i g n i f i c a n t ; however, the f i r s t order i n t e r a c t i o n , v a r i e t y x truss, i s approaching s i g n i f i c a n t and when used as the t e s t i n g term the primary effects of v a r i e t i e s are non-significant, as shown i n Table 4. Thus, v a r i e t a l dif-i ference under the conditions of t h i s experiment i s shown by the f i r s t two trusses only. Table 5» Number of flower buds formed on the f i r s t four trusses of Puck and Bonny Best grown at the warm temperature Truss 1 Truss 2 Truss 3 Truss 4 Total Puck Block 1 20 8 12 38 78 Block 2 19 22 29 15 85 Block 3 22 16 28 19 85 Block 4 22 24 21" 14 81 Total 83 70 90 86 329 Bonny Best Block 1 13 13 16 18 60 Block 2 9 14 10 12 45 Block 3 11 19 14 23 67 Block 4 9 12 17 19 57 Total 42 58 57 72 229 -35-Analysis of variance Source S.S. D.F. Mean Square F Required F Total 1,335.88 31 43.09 5% 1% Variety- 312.50 1 312.50 12.30 10.13 34.12 Truss 92.63 3 30.88 Block 31.38 3 10.46 Variety x Truss 76.25 3 2.5.41 3.86 6.99 Varietyx Block 40.50 3 13.50 3.86 6.99 Truss x Block 351.87 9 39.09 Error 430.75 9 47.86 L.S.D. between variety t o t a l s at odds of 19:1 i s 90.68 L.S.D. between var i e t y t o t a l s at odds of 99:1 i s 166.53 Data i n Table 5 show that Puck had produced more blossoms than Bonny Best on the f i r s t four trusses at the warm temperature, and the difference was s i g n i f i c a n t . Data i n Tables 4 and 5 show that there was an increase i n the number of flower buds induced and i n i t i a t e d at the cool temperature as compared to the warm temperature. These r e s u l t s confirm the reports of Lewis (26) and Calvert (10). As seen by inspection of data i n Table 6, hand p o l l i n a t i o n increased the amount of f r u i t set at the cool temperature, with the increase being much greater f o r Puck than for Bonny Best. Data on f r u i t set at the cool temperature f o r Puck and Bonny Best with no p o l l i n a t i o n s i s given i n Table 7 and s i m i l a r l y data on f r u i t set with hand p o l l i n a t i o n s i s given i n Table 8. -36-Table 6. F r u i t set at the cool temperature on Puck and Bonny Best plants comparing hand p o l l i n a t i o n with no p o l l i n a t i o n Variety Treatment Number of f r u i t Puck hand p o l l i n a t i o n 553 Bonny Best hand p o l l i n a t i o n 196 Puck no^pollination 313 Bonny Best no p o l l i n a t i o n 167 Table 7. Number of f r u i t set for non-pollinated treatment of Puck and Bonny Best grown at the cool temperature Puck Bonny Best Total Block 1 Block 2 Block 3 Block 4 21 109 31 152 31 50 42 44 • 52 159 73 196 Total 313 167 480 Analysis of variance Source S.S. D.F. Mean Square F Required F Total Variety Block Error 14,784.00 7 2,664.50 1 7,065.00 3 5,054.50 3 2,664.50 2,355.00 1,684.83 1.58 1.40 5% 1% 10.13 34.12 9.28 29.46 L.S.D. between var i e t y t o t a l s at odds of 19:1 i s 369.4 L.S.D. between var i e t y t o t a l s at odds of 99:1 i s 678.4. In Table 7 i t i s seen that the difference i n f r u i t set between the two v a r i e t i e s i s not s i g n i f i c a n t . Also, the difference i n blocks i s not s i g n i f i c a n t . There i s , however, great v a r i a b i l i t y between Puck blocks. In blocks -37-1 and 3, the small amount of f r u i t set was probably the result of aphid i n f e s t a t i o n , which was l o c a l i z e d and per-sistent, despite spraying and fumigation. Bonny Best plants were not nearly as susceptible to aphid i n j u r y as Puck plants. The presence of aphids may have v i t i a t e d " these r e s u l t s . Table 8. Number of f r u i t set i n p o l l i n a t e d treatment of Puck and Bonny Best grown at the cool temperature Puck Bonny Best Total Block 1 126 47 173 Block 2 147 47 194 Block 3 142 48 190 Block 4 138 54 192 Total 553 196 749 Analysis of variance Source S.S. D.F. Mean Square F Required F 16 5% 1% Total ,205.88 7 Variety 15 ,931.13 1 15,931.13 353.0810,13 34.12 Block 139.38 3 46.46 Error 135.37 3 45.12 L.S.D. between variety t o t a l s at odds of 19:1 i s 60.4 L.S.D. between v a r i e t y t o t a l s at odds of 99:1 i s 110.9. In Table 8 i t i s seen that hand p o l l i n a t i o n s at the cool temperature gave highly s i g n i f i c a n t differences between the two v a r i e t i e s i n favour of Puck. It had been noted from macroexaminations for po l -len production that Bonny Best produced l i t t l e pollen at -38-the cool temperature; therefore, i t was suspected that the f r u i t set was l a r g e l y parthenocarpic. It was thought, how-ever, that the f r u i t set from hand po l l i n a t e d flowers of Bonny Best would contain seed, but an examination of f r u i t from both Puck and Bonny Best from non-pollinated and hand-po l l i n a t e d flowers as shown i n Table 9 did not substantiate t h i s expectation. Table 9. Eff e c t s of hand p o l l i n a t i o n on the formation of parthenocarpic f r u i t i n Puck and Bonny Best grown at the cool temperature Variety Treatment _ Number of Number of f r u i t f r u i t examined parthenocarpic Puck no p o l l i n a t i o n 10 7 Bonny Best no p o l l i n a t i o n 10 10 Puck hand p o l l i n a t i o n 10 0 Bonny Best hand p o l l i n a t i o n 10 9 The outstanding feature shown i n Table 9 i s that Bonny Best f r u i t , , with one exception, was parthenocarpic, despite the fact that pollen had been applied. A l l Puck f r u i t , under similar conditions, had seed. The difference between the two v a r i e t i e s shows that Puck pollen applied to the stigmatic surfaces was better able to germinate, grow down the st y l e s , and f e r t i l i z e the ovules, than was Bonny Best pollen. These re s u l t s are comparable to the observations of Bohn (2). -39-2. F i e l d experiment The 1954 season was conducive to satisfactory-growth of tomatoes i n the f i e l d . The temperatures, a l -though not optimum f o r commercial tomato production, were too warm to permit Puck to demonstrate i t s alleged capacity to set and develop f r u i t at consistently cool temperatures. It was not possible to take measurements on y i e l d data due to the high incidence of both l a t e b l i g h t and blossom end r o t . Table 10. F i r s t flower production i n a l l l i n e s , compared with Puck Variety Date Number of blossoms Total number of blossoms on Puck at t h i s time Puck 498 Puck x 498 498 x Puck Bonny Best June 1 June 19 June 10 June 6 June 23 1 6 2 3 3 61 18 7 138 Table 11. F i r s t f r u i t set i n a l l l i n e s , compared with Puck Number W u m b e r °f f r u i t Interval between Date - f set on Puck at f i r s t blossom oi i r u r c t h i g t i m e a n d f r u i t s e t Variety Puck June 14 2 498 June 28 1 Puck x 498 June 23 1 498 x Puck June 19 3 Bonny Best July 3 15 40 19 4 59 13 days 9 days 13 days 13 days 10 days -40-Table 12. F i r s t ripe f r u i t i n a l l l i n e s Variety Date Number of ripe f r u i t Puck- August 13 1 498 August 13 4 Puck x 498 August 21 1 498 x Puck August 21 7 Bonny Best August 13 1 In Tables 10 and 11 i t i s shown that Puck pro-duced flowers and set f r u i t e a r l i e r than a l l of the other l i n e s ; however, Table 12 shows that Puck did not ripen f r u i t any e a r l i e r than Bonny Best and 498. Table 13• Blossom production and f r u i t set on the f i r s t four trusses f o r the f i e l d experiment with cumulative data recorded as an average per plot of eight plants Blossom production Variety June 28 July 18 July 31 August 21 Puck 69.8 233.0 299.0 498 24.6 146.8 261.4 -Puck x 498 28.8 158.2 261.2 -498 x Puck 37.8 147.2 230.2 -Bonny Best 10.4 92.2 175.0 — L.S.D. ( 5 % ) 8.41 20.10 30.40 _ L.S.D. (136) 11.79 28.17 42.55 — F r u i t set Variety June 28 July 18 July 31 August 21 Puck 8.0 56.4 144.4 150.2 498 2.0 42.8 87.8 161.4 Puck x 498 1.2 51.0 136.0 253.2 498 x Puck 7.2 46.0 114.4 215.2 Bonny Best 0.0 32.0 52.6 137.2 L.S.D. (5#) 3.49 15.60 26.97 27.51 L.S.D. (1$) 4.89 21.83 37.79 38.49. -41-The analysis of data which are summarized i n Table 13 i s given i n the appendix. June 28 was the l a s t date for which there was no f r u i t set i n Bonny Best and, therefore, t h i s date shows the earliness of the other l i n e s . F r u i t set by July 18 would be i n d i c a t i v e of early y i e l d , i f s i x weeks i s considered as the average time between f r u i t set and ripe f r u i t . F r u i t set between July 18 and July 31 would be i n d i c a t i v e of mid-season y i e l d . F r u i t set up to August 21 would be i n d i c a t i v e i n an average season of t o t a l y i e l d . In Table 13 i t i s noted that on June 28 Puck had produced more blossoms than a l l the other v a r i e t i e s , whereas Bonny Best had fewer blossoms than the others. These d i f f e r ences were highly s i g n i f i c a n t , and were maintained i n the July 18 and July 31 data. On June 28 there were no s i g n i f -icant differences between the number of blossoms produced by 498 and the hybrid, Puck x 498. The hybrid 498 x Puck, however, had produced a larger number of blossoms r e s u l t i n g i n a highly s i g n i f i c a n t increase over 498 and a s i g n i f i c a n t increase over Puck x 498. On July 18, however, there were no s i g n i f i c a n t differences among the three l i n e s , while on July 31 Puck x 498 and 498 had produced s i g n i f i c a n t l y more blossoms than 498 x Puck, thus reversing the trend evident on June 28. July 31 was the f i r s t date where there was no highly s i g n i f i c a n t difference i n the number of blossoms -42-produced i n Puck, as compared to Puck x 498. From Table 13 i t i s noted that by June 28, Puck and the Hybrid 498 x Puck had set more f r u i t than the other v a r i e t i e s and the increases were highly s i g n i f i c a n t . By July 18 the differences i n f r u i t set between Bonny Best and Puck were s t i l l highly s i g n i f i c a n t . There was, however, no s i g n i f i c a n t difference i n the amount of f r u i t set i n Puck, 498, and the r e c i p r o c a l crosses of these two v a r i e t i e s , although the difference between 498 and Puck was approaching s i g n i f i c a n c e . By July 31 the f r u i t set i n Puck and i n Puck x 498 was greater than the f r u i t set i n both 498 and Bonny Best, and these differences were highly s i g n i f i c a n t . The increase i n the amount of f r u i t set i n Puck x 498 as compared to 498 x Puck was approaching the s i g n i f i c a n t l e v e l . By August 21 the f r u i t set i n Puck x 498 was greater than i n a l l other l i n e s and these differences were highly s i g n i f i c a n t i n a l l cases, with the exception of 498 x Puck where the difference was approaching the highly s i g n i f i c a n t l e v e l . This, also, i s a reversal i n the trend evident on June 28, where 498 x Puck had set more f r u i t than Puck x 498. The analysis of the data which are summarized i n Table 14 i s given i n the appendix. -43-Table 14. Ripe f r u i t u n t i l September 11, recorded as an average per plot of eight plants Variety- Number of f r u i t Puck 30.2 498 32.4 Puck x 498 44.6 498 x Puck 36.6 Bonny Best 38.4 L.S.D. at odds of 19:1 i s 12.77 L.S.D. at odds of 99:1 i s 17.90. By September 11, as seen in Table 14, 498 had produced s i g n i f i c a n t l y more ripe f r u i t than Puck. There were no s i g n i f i c a n t differences among the other v a r i e t i e s , although the difference between 498 and Bonny Best ap-proached sign i f i c a n c e . Table 15. Temperature records i n degrees Fahrenheit f o r duration of f i e l d experiment , , Date Ave. min. temp. Ave. max. temp. Low min. temp. High max. temp. May 27 June 1 44.90 61.70 40.00 68.00 June 1 - June 6 43.42 59.00 40.50 65.00 June 6 - June 10 47.40 60.30 45.50 64.00 June 10 - June 14 48.40 61.20 45.50 64.00 June 14 - June 19 45.66 58.66 41.50 61.50 June 19 - June 23 46.80 63.50 44.00 70.00 June 23 - June 28 49.17 65.75 44.00 73.00 June 28 - July 3 49.42 63.75 44.50 72.00 July 3 - July 7 49.90 67.20 44.50 72.00 July 7 - July 12 50.83 64.25 48.00 68.00 July 12 - July 18 49.93 67.86 48.00 73.00 July 18 - July 24 50.36 65.64 47.00 70.00 July 24 - July 31 48.19 69.62 46.00 74.00 -44-The temperatures were not taken d i r e c t l y from the area of the p l o t s , but were recorded at a central point on the experimental s t a t i o n . Minimum grass temperatures were also recorded at t h i s point and were usually several degrees lower than the minimum temperature; thus, the tomato plants were probably exposed to lower temperatures than shownin Table 15. In addition to blossom production and f r u i t setting observations for the f i e l d experiment, there were two obser-vations made on other aspects of plant and f r u i t development. F i r s t , at the time of transplanting i t was noted that plants of the r e c i p r o c a l crosses were larger than the plants of either parent. Second, the f r u i t set i n both the r e c i p r o c a l crosses and i n the Puck parent was generally smooth and even i n form, compared to the very i r r e g u l a r shaped f r u i t which was c h a r a c t e r i s t i c of 498. The f r u i t of Bonny Best was i n -termediate i n form between the two types. 3. H i s t o l o g i c a l and c y t o l o g i c a l experiments (a) Meiosis ( l ) Warm temperature The average per cent of normal meiosis from exam-inat i o n of flower buds grown at the warm temperature was 96 per cent. These buds included f i v e from Puck, four from Bonny Best, and three from Gem. Buds of Puck showing meiosis - 4 5 -ranged i n length from 4.0 mm. to 4.9 mm., while i n Bonny Best the length was from 2.5 mm. to 5*1 mm. and i n Gem from 4*5 mm. to 5.0 mm. (2) Cool temperature The average per cent of normal meiosis i n flower buds from a l l l i n e s grown at the cool temperature was much more variable than at the warm temperature. Table 16. Average per. cent of normal meiosis i n pollen mother c e l l s of buds of Puck and Bonny Best grown at the cool temperature Variety No. of buds examined Per cent normal meiosis Average temperature range within 24 hours pr i o r to k i l l i n g and f i x i n g Puck Bonny Best 10 8 s a . 5 65.0 6.20° F. 6.44° F. Data i n Table 16 show 23 per cent more abnormal meiotic d i v i s i o n s i n Bonny Best pollen mother c e l l s than i n Puck. At t h i s cool temperature buds of Puck, showing meiosis i n pollen mother c e l l s , had an average length of 3.4 mm. with a range of 3.0 mm. to 3.8 mm., while buds of Bonny Best had an average length of 4.0 mm. with a range of 2.7 mm. to 5.4 mm • The range of temperature f l u c t u a t i o n , within 24 hours prior to removing buds for k i l l i n g and f i x i n g was 2° - 4 6 -to 10° F. for Puck and 4° to 10.5° F. for Bonny Best. A greater temperature fluctuation gave an increase in the number, of irregular meiotic divisions in Puck. For example a fluctuation of 13° F. in the cool house within 24 hours prior to k i l l i n g and fixing gave only 27•9 per cent normal meiosis in three buds examined. These buds ranged in length from 2.3 mm. to 2.5 mm. A fluctuation of 14° F. produced 18 hours prior to k i l l i n g and fixing, by the tran-sfer of one plant of Puck from the cool temperature to the warm temperature for 2\ hours, resulted in 72.06 per cent normal meiosis in four buds examined. In this second ex-ample i t should be noted that the temperature fluctuation is in a warmer range than in the f i r s t example. Bonny Best pollen mother cells were more variable in response to temperature fluctuations than Puck. For example a tempera-ture range of 6° F. within 24 hours prior to k i l l i n g and fixing gave 22.0 per cent normal meiosis in a bud of Bonny Best, while a similar range for a different bud gave 77»5 per cent normal meiosis. A temperature fluctuation of 10.5° F. at the cool temperature gave only 31»6 per cent normal meiosis in the pollen mother cells of s t i l l another Bonny Best bud. In contrast, in the Puck buds examined the per cent of normal meiosis was only reduced drastically by temperature fluctuations of 13° to 14° F. -47-normal Cool temperatures did not greatly reduce/meiosis i n the other l i n e s , as shown i n Table 17. Table 1?. Average percentage of normal meiosis i n pollen mother c e l l s of four l i n e s of tomatoes grown at the cool temperature Line Number of buds examined Number of buds showing meiosis Per cent normal meiosis Average length of bud showing meiosis 498 5 2 89.6 3.6 mm. Puck x 498 6 2 87.8 3.6 mm. 498 x Puck 3 0 - -Gem 3 3 82.9 4*1 mm• Early Chatham 5 3 86.9 3.5 mm. Regarding Table 17, the buds examined which were not showing meiosis a l l had numerous normal appearing t e t -rads. Thus, i t can be assumed that a large proportion of the meiotic d i v i s i o n s were normal. Meiosis i n the pollen mother c e l l s of the l i n e s 498, Early Chatham, and Puck x 498 did not appear to be affected by fluctuations i n temperatures, since a change of 13° F. within 24 hours pr i o r to k i l l i n g and f i x i n g did not reduce the per cent of normal meiosis i n any one l i n e . The greatest temperature f l u c t u a t i o n within 24 hours, recorded for Gem, was 10° F. and t h i s did not reduce the per cent of normal meiosis. -48-There were f i v e stages where meiotic i r r e g u l a r i t i e s occurring at lower temperatures were easy to observe i n the pollen mother c e l l s . These stages, the type of abnormality and the per cent of the type out of 360 abnormal pollen mother c e l l s examined are as follows. (1) Prophase I, diplotene or diakinesis showing fragmenta-t i o n of the chromosomes, 6 per cent. (2) Prophase I, diakinesis showing i r r e g u l a r p a i r i n g , with the resultant appearance of bivalents and univalents, 40 per cent. (3) Metaphase I or I I showing lagging chromosomes or pre-mature migration of the chromosomes, 13 per cent. ( 4 ) Anaphase I or II showing non-simultaneous separation of chromosomes, 37 per cent. (5) Telophase I or II showing more than 12 chromosomes or chromatids respectively, 4 per cent. These abnormalities are i l l u s t r a t e d i n figures 1 to 3. The percentages or meiotic i r r e g u l a r i t i e s recorded for any of the v a r i e t i e s grown at the cool temperature were not high enough to explain the lack of pollen observed i n macroexaminations; therefore, i t was assumed that pollen degenerated a f t e r the formation of the tetrads. - 4 9 -Figure 1 . Normal meiosis i n p o l l e n mother c e l l s of the . tomato (x 1 9 0 0 ) . A. Prophase'I. D i a k i n e s i s showing 1 2 pairs' of chromosomes. B. Anaphase I . Showing simultaneous sepa r a t i o n . C. Telophase I . Showing two groups of chromosomes. D. Metaphase I I . Showing chromosome groups i n two d i f f e r e n t planes. -50-Figure 2. Abnormal meiosis, induced by low temperatures, i n p o l l e n mother c e l l s of the tomato (x 1900). A. Prophase X. B. Prophase I . C. Anaphase I . D. Anaphase I . Diplotene showing fragmentation of chromo-somes and n u c l e o l i . D i a k i n e s i s showing a u n i v a l e n t ( u ) . Showing non-simultaneous se p a r a t i o n . Showing e i t h e r non-simultaneous sep a r a t i o n of chromosomes or l a g g i n g chromosomes. -51-Figure 3. Abnormal m e i o s i s , induced by low temperatures, . i n p o l l e n mother c e l l s of the tomato (x 1900). A* Telophase I * Showing r e s u l t s of asynapsis or desynapsis. B. Anaphase I I . Showing non-simultaneous sepa r a t i o n . C. Telophase I I . Showing i r r e g u l a r groupings of chromosomes. -52-(b) Pollen v i a b i l i t y Both actocarmine and iodine-potassium iodide d i f -ferentiated c l e a r l y between viable and non-viable p o l l e n . Pollen of flowers taken at anthesis showed d i s t i n c t d i f -ferences when stained with acetocarmine. Viable pollen containing cytoplasm stained a red colour. Non-viable or aborted pollen, containing no cytoplasm did not st a i n and appeared colourless and s h r i v e l l e d . There was an i n t e r -mediated condition where there was a small amount of cyto-plasm i n some of the pollen grains. Such grains stained a l i g h t red and were f a i r l y common i n flowers at the cool temperature taken p r i o r to anthesis. Figure 4 i l l u s t r a t e s the difference between viable and aborted pollen using acetocarmine s t a i n . Pollen of flowers taken at anthesis also showed d i s t i n c t differences when stained with iodine-potassium iodide solution. Viable pollen stained a dark blue-red to black colour, whereas non-viable pollen stained a pale yellow colour and also appeared s h r i v e l l e d . A l l pollen from flowers p r i o r to anthesis stained a yellow colour; however, there was an intermediate condition, where the pollen stained a brown colour. The stage at which the pollen degenerated follow-ing telophase II was varia b l e . For instance i n several buds -53-of Bonny Best degeneration was observed immediately a f t e r the formation of the microspore t e t r a d s . In the m a j o r i t y of buds of a l l l i n e s , however, degeneration occurred much l a t e r and no i n f r e q u e n t l y , j u s t p r i o r to a n t h e s i s . A l l counts were made, t h e r e f o r e , on flowers at anthesis i n order to insure that maximum degeneration would have occurred. Figure 4 » Microphotograph of acetocarmine smear pr e p a r a t i o n of normal or v i a b l e p o l l e n (dark stained bodies) and aborted or non-viable p o l l e n ( l i g h t s t a i n e d bodies) from anthers of flowers of Puck grown at the cool temperature (X515) -54-The pollen v i a b i l i t y counts, showing the e f f e c t of the cool temperatures are presented i n Table 18. There was a large amount of v a r i a b i l i t y i n these r e s u l t s , sub-sequently i t was r e a l i z e d that conditions for plant growth i n the cool house varied and, that i n sampling for micro-scopic examination, the several growing conditions had not been considered. Table 18. Average per cent of viable pollen produced by s i x tomato l i n e s grown under variable environmental con-diti o n s at the cool temperature Line Number of flowers examined Per cent normal pollen (ave.) Range of viable pollen i n per cent Puck 30 19.4 0.0 - 86.6 498 16 2.1 0.0 - 21.6 Puck x 498 19 6.6 .3 : - 35.3 Bonny Best 15 10.1 0.0 - 88.0 Gem 25 12.4 0.0 - 85.0 E a r l y Chatham 12 2.2 0.0 - 13.5 The variations i n growing conditions arose from di f f e r e n t s o i l conditions and from d i f f e r e n t positions of the plants within the cool house. Plants were grown i n benches of s o i l along the sides of the cool house and i n pots on benches i n the centre of the house. There were more nutrients available to the plants i n the benches due -55-to a larger volume of s o i l . Also a warmer temperature existed around the s o i l benches because the heating pipes were underneath and thus raised the temperature on the surface of the benches at least 2° F. higher than the rest of the house. Furthermore, the temperature around the roots of the plants in the benches was probably higher than on the surface, since the roots were that much closer to the pipes. This temperature difference would .contribute to an increased nutrient uptake for plants in the benches. The plants in the pots were more restricted for volume of s o i l and did not have the temperature advantage. Since there was this vari a b i l i t y in conditions, the next sample of buds was restricted to bench plants as shown in Table 19 and the following sample to pot plants as shown in Table 20. Table 19. Average per cent viable pollen produced by toma-to lines grown in benches of s o i l at the cool temperature Number of _ . , Range of viable Line flowers P e r c e n t formal pollen in per cent i l o w e r s 1" X" examined P o l l e n ^ a v e ^ Puck 10 498 10 Puck x 498 10 Bonny Best 10 Gem 10 Early Chatham 10 49.3 24.7 15.5 45.6 15.1 3.4 3.3 .3 1.0 3.0 0.0 0.0 79.5 81.0 75.3 91.0 56.0 10.0 - 5 6 -In Table 19, i t i s seen that the amount of viable pollen produced by Bonny Best i s considerably higher than that observed from macroexaminations of other plants. There seems to be a reasonable explanation for t h i s high amount. The flowers of Bonny Best for the microscopic ex-amination came from the spe c i a l plant of the variety grown i n the bench for t h i s purpose. This plant, which was not pruned, was grown on the outside of the bench adjacent to the glass wall and had one shoot that consistently produced flowers, which hung over the bench. Such a position placed these flowers i n the warm a i r current from the pipes. This a i r was considerably warmer than a i r elsewhere along the bench. Macroexaminations of the flowers from t h i s shoot also revealed abundant quantities of pollen and the data in Table 19 support t h i s f a c t ; thus, the conditions f o r the Bonny Best plant were not representative of the cool temperature. The data i n Table 20 s t i l l shovr a higher per cent of viable pollen for Bonny Best than had been reported by previous macroexamination. Also, a higher per cent of viable pollen i n Puck x 498 i s noted than was reported i n Tables 18 and 19. There were no s a t i s f a c t o r y explanation, for the inconsistencies i n both l i n e s , other than lack of precise control of environment. - 5 7 -Table 2 0 . Average per cent of viable pollen produced by-s i x tomato l i n e s grown i n pots at the cool temperature Line Number of flowers examined Per cent normal pollen (ave.) Range of vi a b l e pollen i n per cent Puck 1 0 8 . 1 . 6 2 0 . 6 4 9 8 1 0 5 . 0 1 . 0 1 1 . 6 Puck x 4 9 8 1 0 3 2 . 0 1 . 6 - 6 6 . 6 Bonny Best 1 0 8 . 1 0 . 0 2 9 . 9 Gen 1 0 2 . 3 . . 6 6 . 6 Early Chatham 1 0 1 . 9 . 3 4 . 6 Because of the apparent inconsistencies reported for Bonny Best and Puck i n the three previous sampling pro-cedures, a f i n a l sample of buds was taken at random from the plants i n the benches which had r e l a t i v e l y uniform con-d i t i o n s . The r e s u l t s , i n Table 2 1 , indicated that under cool temperatures, a l l other conditions being equal, Puck produced about 2 2 per cent more viable pollen than Bonny Best. The per cent for Bonny Best i s frequently so low that, 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 may not occur for suc-cessful f r u i t set. Table 2 1 . Average per cent of viable pollen produced by twenty flowers each of Puck and Bonny Best grown i n benches at the cool temperature Line A p r i l 13 A p r i l 16 Average Range of viable pollen in per cent Puck Bonny Best 33.0 2 . 9 16.8 2 . 2 2 4 . 9 2 . 5 .6 - 83.0 .3 - 10.0 -58- • Pollen germination The germination of pollen was successfully e s t i -mated with either of two stains. Acid fuschin - l i g h t green stained ungerminated pollen grains of a dark fuschia colour; newly germinated grains stained a l i g h t e r colour; while grains which had germinated sometime previous to k i l l i n g and f i x i n g stained a very pale blue colour. It was not possible to trace the pollen tubes down the sty l e using t h i s method, since the portion of the pollen tube containing cytoplasm stained a dark fuschia colour, similar to the s t y l a r t i s s u e . Acetocarmine stained ungerminated pollen grains a red colour. Newly germinated grains were a l i g h t e r red i n colour, while grains which had germinated sometime previous to k i l l i n g and f i x i n g were colourless. It was not possible to d i f f e r e n t i a t e pollen tubes from st y l a r tissue using acetocarmine. Since both stains were equally e f f e c t i v e , the counts on pollen germination using acid fuschin, l i g h t green and those using acetocarmine were combined. Table 22. Average per cent germination of pollen of Puck and Bonny Best tomatoes as affected by temperature Variety Temperature Number of flowers examined Average per cent germination Puck warm 6 75.5 Bonny Best warm 5 81.9 Puck cool 5 87.5 Bonny Best cool 7 33.0 -59-In Table 22 i t i s shown that Puck pollen, pro-duced at a temperature of 60° to 65° F.,can germinate better at a temperature of 50° to 55° F. than Bonny Best pollen under similar conditions. The lowest per cent germination i n Bonny Best at the cool temperature occurred on stigmatic surfaces of fasciated s t y l e s . (c) Pollen production Under the warm temperature, flowers of a l l l i n e s consistently produced pollen. Under the cool temperature, the number of flowers producing pollen was reduced i n a l l l i n e s as noted i n Table 2 3 . This reduction i n pollen was s u f f i c i e n t l y great to resu l t i n many flowers maturing no pollen which could be detected by macroexamination. Table 23. Pollen production, throughout the winter of 1954-1955, as determined by macroexamination i n seven d i f f e r e n t l i n e s of tomatoes grown at the cool temperature Number of Per cent of flowers Line flowers examined producing examined pollen Puck 82 46.34 498 34 32.35 Puck x 498 74 44.59 498 x Puck 53 54.72 Bonny Best 22 27.27 Gem 47 31.91 Early Chatham 58 17.24 Since an equal number of plants were used i n each l i n e , the number of blossoms recorded i n Table 23 i s an i n -dicat i o n of the e f f i c i e n c y of the d i f f e r e n t l i n e s to produce blossoms at the cool temperature. -60-DISCUSSION Several important differences between Puck and Bonny Best v a r i e t i e s were shown i n blossom production and f r u i t set at cool temperatures (50° to 55° F.) i n the greenhouse experiments. F i r s t , Puck produced more blos-two soms on the f i r s t / trussesthan did Bonny Best, and the greater number of blossoms would give a greater opportunity for a larger number of f r u i t to set. This s i t u a t i o n may give the appearance of greater early f r u i t . s e t t i n g character to a casual observer. The second difference was the produc-t i o n of about eighteen to twenty trusses per plant of Puck i n contrast to the f i v e or s i x developed by Bonny Best during the same period. Thus, Puck had an advantage i n t o t a l number of blossoms per plant. A t h i r d difference was that Puck produced a far greater number of normal blossoms than Bonny Best, and normal blossoms are more l i k e l y tp set and to develop regular f r u i t than w i l l ab-normal blossoms. F i n a l l y , i n both experiments, Puck set and developed more f r u i t at the cool temperature than did Bonny Best, which may of course be pa r t l y due to tempera-ture effect on production of normal blossoms as well as the effect on subsequent p o l l i n a t i o n and development. Individual blossoms of Puck appeared to have one i n i t i a l advantage for f r u i t set over Bonny Best blossoms, -61-namely, the production of more pollen. The microscopic ex-aminations to ascertain pollen v i a b i l i t y , however, revealed that there was a great deal more v a r i a b i l i t y i n pollen production i n d i f f e r e n t l i n e s under cool temperature con-di t i o n s than was evident from the r e s u l t s of macroexamina-ti o n s . The microscopic examinations showed that s l i g h t environmental variations had an important effect on pollen production and these effects would probably be representa-t i v e of f i e l d conditions. The differences i n pollen pro-duction between l i n e s of tomatoes could be dependent on genotypic differences i n exploiting the microenvironment. For example, since pollen production i s affected by carbo-hydrate l e v e l within the plant (17)i the available n u t r i -ents and t h e i r absorption would be very important. Sligh t fluctuations i n other, environmental factors, such as r e l a -t i v e humidity, l i g h t i n t e n s i t y and temperature, might mod-i f y pollen production either d i r e c t l y or i n d i r e c t l y . Despite the great v a r i a b i l i t y i n pollen production, there are two i n t e r e s t i n g trends which emerge from both the micro and macroexaminations. - F i r s t , Puck consistently produced, to a greater or lesser extent, more pollen than a l l the other l i n e s . Second, the r e c i p r o c a l crosses of Puck x 498 and 498 x Puck produced more pollen at the cool temperature than the other l i n e s , excluding Puck. Pollen -62-production i n Puck x 498 was intermediate between the two parents. This suggests p a r t i a l dominance of the' character of pollen production. A difference between viable and non-viable p o l -len and thus a difference i n the amount of functional pol-len developed may be related to starch synthesis. It was observed that viable grains stained dark blue colour with iodine-potassium iodide and thus contained starch. Non-viable or aborted pollen at anthesis, and a l l pollen p r i o r to anthesis, Slowed an absence of starch, i n d i c a t i n g that viable pollen grains synthesized starch as they matured, whereas non-viable pollen grains did not. These observa-tion s , i n view of Howlett's (17) statement that male ster-i l i t y resulted from a carbohydrate deficiency, could mean that there was not a suitable l e v e l of simple sugar a v a i l -able for starch synthesis i n the pollen grains of male s t e r i l e plants. The observations of starch synthesis i n viable pollen grains confirm Maheshwari's (28) general statement on the synthesis of starch as functional pollen grains mature, and contradicts Lesley and Lesley's (24) conclusion that starch was hydrolyzed to sugars as functional grains mature. One difference between the non-viable and the viable pollen grains appears to be that the l a t t e r can synthesize starch as they mature; however, i t cannot be -63-concluded that t h i s i s the only difference between the two types of pollen grains. Probably there are several d i f -ferences of a biochemical nature between the two types. Various genotypes may control these biochemical processes leading to production of normal pollen i n d i f f e r e n t ways. It was not possible to make a comparison of per cent germination of the viable pollen produced by Puck and Bonny Best at the cool temperature, because of the lack of Bonny Best pollen. The pollen germination t e s t s , therefore, had to u t i l i z e pollen produced at the warm temperature and thus i t can only be inferred that Puck pollen produced at the cool temperature would germinate better at the cool temperature than Bonny Best pollen pro-duced and germinated under similar conditions. It i s int e r e s t i n g to note that pollen applied to fasciated styles of Bonny Best showed a r e l a t i v e l y low per cent germination, whereas the single non-fasciated style of Bonny Best examined showed a high per cent pollen germination. Possibly the stigmatic surface or more spec-i f i c a l l y , the stigmatic f l u i d of a fasciated s t y l e does not have the appropriate properties to permit optimum germina-t i o n . The majority of styles of Bonny Best at the cool temperature was fasciated and thus per cent pollen germina-t i o n was lowered. -64-The lowered pollen germination may explain the parthenocarpic f r u i t produced by Bonny Best at the cool temperature despite hand p o l l i n a t i o n s . Both v a r i e t i e s were able to produce parthenocarpic f r u i t at the cool temperature, but Puck w i l l produce f r u i t with seed when there i s pollen a v a i l a b l e . Meiosis As was the case with pollen v i a b i l i t y at the cool temperature, the occurrence of normal meiosis was variable and no doubt sensitive to microenvironment. Each type of abnormality observed could have resulted from one of several causes. For instance, i r r e g u l a r p a i r i n g at diakinesis (Figure 2, B), r e s u l t i n g i n univalents as well as bivalents, was the r e s u l t of either asynapsis or desynap-s i s . The l a t t e r occurs when the paired chromosomes f a l l apart i n late pachytene or early diplotene, whereas asynap-s i s occurs when there i s a complete lack of pai r i n g i n early prophase. It i s d i f f i c u l t to say which of these phenomena are involved here. The characters of asynapsis and desynap-s i s are extremely variable and are markedly influenced by temperature. L i , Pao, and L i (27) found that desynapsis i n pollen mother c e l l s of wheat was shown at lower tempera-tures, with the bivalent frequency increasing with r i s e s i n temperature. Goodspeed and Avery (15) described asynapsis -65-Nicotiana s y l v e s t r i s and found i t to be a function of the phys i o l o g i c a l conditions i n the c e l l under the influence of both genetic factors and environmental factors. High a i r temperature accompanied by low humidity induced ex-treme asynapsis i n plants which under conditions of a higher humidity and lo\*er temperature showed l i t t l e or no asynapsis. $oost ( 3 9 ) , using tomatoes, found an asynaptic gene which gave r i s e to variable p a i r i n g at pachytene and resulted i n aborted pollen. He assumed that a temperature of 92° F. caused a greater amount of asynapsis than a temperature of 55° F. In the examples mentioned both asyn-apsis and desynapsis have been at t r i b u t e d to a single re-cessive gene. The variable appearance of univalents i n the l i n e s studied here would suggest that asynapsis or desynap-si s was controlled by a number of genes which are greatly influenced by external conditions. Asynapsis or desynapsis could also be the cause of the meiotic i r r e g u l a r i t y i l l u s t r a t e d i n Figure 2, D. In t h i s case i t i s d i f f i c u l t to know whether the two chrom-osomes which are not lined-up are lagging from the meta-phase plate or whether they are separating prematurely. The two chromosomes may well be univalents that did not mi-grate to the metaphase plate. Asynapsis or desynapsis could also have led to the abnormality i l l u s t r a t e d i n Figure 2, C. / -66-The chromosome, which i s out of l i n e , however, could have separated prematurely. Such an uneven placement of chromo-somes during anaphase could lead to a si t u a t i o n l i k e that i l l u s t r a t e d i n Figure 3, C. This l a t t e r abnormality also could have resulted from univalents rounding up and form-ing groups of n u c l e i i containing less than twelve chromo-somes. The ultimate r e s u l t of t h i s would be aborted pollen. Fragmentation of chromosomes, as i l l u s t r a t e d i n Figure 2, A, was the most prevalent abnormality occurring when there was a greater than usual f l u c t u a t i o n i n temper-ature; for instance, i t was common i n pollen mother c e l l s of Puck when they were subject to a change i n temperature from 49° to 62° F. within 24 hours p r i o r to k i l l i n g and f i x -ing. These re s u l t s are similar to those of Sax (35), who found that a marked temperature f l u c t u a t i o n caused frag-mentation i n Tradescantia pollen mother c e l l s . It i s of inte r e s t to note that a temperature fl u c t u a t i o n of 56° to 70° F. within 24 hours pr i o r to k i l l i n g and f i x i n g gave only 23 per cent normal meiosis compared to 70 per cent abnormal meiosis for a f l u c t u a t i o n of 49° to 62° F. It appears that fluctuations at a warmer temperature do not a f f e c t meiosis to the same degree as fluctuations at a cooler.temperature. The greater per cent of abnormal meiotic d i v i s i o n s following a f l u c t u a t i o n i n -67-temperature compared to a constant sub-optimum temperature has been observed for a number of speciesj for instance, Sax (35) found i t i n Tradescantia, Pao and L i (31) i n rye (13) and Emsweller and B r i e r l e y / i n L i l l i u m . From the l i m i t e d amount of data reported here, Bonny Best seems to be more subject to meiotic i r r e g u l a r i t i e s due to temperature f l u c -tuations than the other l i n e s . F i e l d experiment There are two i n t e r e s t i n g trends that emerge from the analysis of blossom production and f r u i t setting a b i l i t y of the f i v e l i n e s studied under f i e l d conditions. The f i r s t of these concerns the performance of Puck. This variety flowered e a r l i e r and subsequently set f r u i t e a r l i e r than the other l i n e s , but did not ripen f r u i t any e a r l i e r . This fact suggests a r e l a t i v e l y long period between f i r s t f r u i t set and f i r s t ripe f r u i t . As the season progressed, the e a r l i e r advantage that Puck possessed with regards to the number of f r u i t set on the f i r s t four trusses was l o s t , and both the hybrids and 498 had more f r u i t ' set than Puck. There are possible explanations for t h i s change. F i r s t , Puck was not pruned to one stem and thus, by August 21st when the differences were most marked, Puck had produced more trusses with f r u i t on them than the other l i n e s . Second, Puck i s inherently small i n growth habit and t h i s - 6 8 -would p o s s i b l y l i m i t f r u i t s e t . Both of these f a c t o r s may have c o n t r i b u t e d to the f a l l i n g - o f f i n f r u i t set i n Puck. The second t r e n d shown concerns the performance of the r e c i p r o c a l c r o s s e s , Puck x 498 and 498 x Puck. On June 28th the cr o s s 498 x Puck had produced s i g n i f i c a n t l y more blossoms than the c r o s s Puck x 498. The former had a l s o set a h i g h l y s i g n i f i c a n t i n c r e a s e i n f r u i t compared to the l a t t e r . By J u l y 18th, however, Puck x 498 had sur-passed 498 x Puck i n both blossom p r o d u c t i o n and i n f r u i t s e t , although the d i f f e r e n c e was not s i g n i f i c a n t . By J u l y 31st, however, Puck x 498 had produced s i g n i f i c a n t l y more blossoms than 498 x Puck, while the i n c r e a s e i n f r u i t set i n Puck x 498 over 498 x Puck approached s i g n i f i c a n c e . On August 23rd the i n c r e a s e i n f r u i t set i n Puck x 498 over 498 x Puck approached a l e v e l of high s i g n i f i c a n c e . Thus, there are obvious d i f f e r e n c e s between the r e c i p r o c a l c r o s s e s . The e a r l y advantages shown by 498 x Puck were not maintained and the advantage was taken over by Puck x 498 l a t e r i n the season. There are s e v e r a l p o s s i b l e reasons f o r t h i s com-p l e x r e l a t i o n s h i p . Cytoplasmic i n h e r i t a n c e appears to be i n v o l v e d . The Puck x 498 cr o s s may have i n h e r i t e d c y t o -plasmic f a c t o r s through the female parent, which enabled the p l a n t to produce a g r e a t e r number of blossoms, which gave a g r e a t e r o p p o r t u n i t y f o r f r u i t s e t . Along w i t h t h i s - 6 9 -feature, factors for lateness may have been inherited, be-cause Puck did not mature f r u i t as quickly as the other l i n e s . Also, Puck x 498 f r u i t did not mature quite as early as 498 x Puck f r u i t . The early advantage of the cross 498 x Puck over Puck x 498 might have been due to an environmental f a c t o r , rather than a genetical one. When 498 was used as the female parent there were very few seeds per f r u i t as com-pared to the number of seeds when Puck was used as the female parent. Richardson and Gurrence (32) found that a reduction i n the number of seeds i n a tomato f r u i t i n -creased i n d i v i d u a l seed weight. The seed of the cross 498 x Puck, therefore, may have been heavier than the seed of the reciprocal.-cross Puck x 498, because Puck gave a par-t i c u l a r l y large number of seeds per f r u i t . The i n i t i a l l y heavier seed of 498 x Puck may have resulted i n an early advantage for th i s l i n e . A f i n a l i n t e r e s t i n g point noted i n the f i e l d experiment i s that the minimum temperatures are well below the 59° F. reported by Went (40) as minimum for f r u i t set i n tomatoes. Learner and Wittwer (22) had modified t h i s report by stating that there was v a r i e t a l response to min-imum temperatures; for example, Ear l y Chatham set appre-ciable f r u i t at night temperatures as low as 40° F., whereas the v a r i e t i e s John Baer and Rutgers required higher temperatur -70-f o r f r u i t set. It i s possible that a l l the l i n e s studied here f a l l into the same class as Early Chatham. By the time Bonny Best had produced blossoms and begun to set f r u i t , however, the lowest minimum temperature recorded was 44.5° F. and thus, i t i s not possible to say whether i t would have, set f r u i t at a temperature of 40° F. It i s also possible that the maximum temperature and the length of time of maximum temperature would tend to offset the effects of low night temperatures, although Went and Cosper (41) claimed that day temperature modified only s l i g h t l y the response to night temperature. It has been frequently assumed by plant breeders that f r u i t set i s a r e l a t i v e l y simple character. The re-sults reported here have indicated that f r u i t set at a r e l a t i v e l y cool temperature i s p a r t i a l l y controlled by blossom production, pollen production and pollen germina-t i o n (or the properties of the stigmatic surface a f f e c t i n g germination of the p o l l e n ) . These.steps are only part of a complete sequence, which would include f l o r a l induction, f l o r a l i n i t i a t i o n , f l o r a l development, including develop-ment of the stamens (formation of pollen mother c e l l s , meiosis and maturation of pollen), and development of the p i s t i l s (formation of embryo sac mother c e l l s , meiosis, and maturation of ovules, as well as style and stigma de-velopment), p o l l i n a t i o n , including germination of pollen -71-and growth of pollen tubes down the st y l e , f e r t i l i z a t i o n and f i n a l l y , development of the embryo. Failur e of any one of these steps to proceed successfully could r e s u l t i n lack of f r u i t . Obviously the f r u i t setting character i s not simple, but extremely complex. A va r i e t y with max-imum e f f i c i e n c y i n setting f r u i t at cool temperatures would have a l l appropriate components of the f r u i t - s e t t i n g char-acter. Puck showed three of these components and further investigations would be required to determine how many more useful components i t possesses. Regardless of how many such useful components Puck possesses, the vari e t y would not be completely desirable because i t has genes which con-tribu t e to la t e ripening of f r u i t and low t o t a l y i e l d . A breeding program would have to evolve around the idea of obtaining as many as possible of the useful components of the f r u i t setting character from Puck, and combining these with desirable characters from other v a r i e t i e s . Such a variety would give greater early and t o t a l y i e l d s i n the present tomato growing regions and also extend the area of pr o f i t a b l e tomato culture i n Canada. SUMMARY AND CONCLUSIONS Most commercial tomato v a r i e t i e s require r e l a -t i v e l y high temperatures for f r u i t set and development, and th i s requirement l i m i t s tomato growing i n the Canadian - 7 2 -a g r i c u l t u r a l areas. There are, however, certain newer var-i e t i e s which are reported to set f r u i t at cool temperatures (below 5 5 ° F.). One such variety, Puck, a non-commercial type was contrasted with the popular commercial v a r i e t i e s , Bonny Best and 4 9 B . Replicated f i e l d and greenhouse ex-periments were done to ascertain the f r u i t setting character of Puck and c y t o l o g i c a l and h i s t o l o g i c a l studies.were con-ducted on some aspects of t h i s character. The re s u l t s are summarized as follows. ( l ) It was found that Puck flowered e a r l i e r and produced more blossoms than the commercial var-i e t i e s and thus had a greater opportunity for f r u i t set at cool temperatures. ( 2 ) It was also found that i n d i v i d u a l Puck blossoms were able to produce more pollen at cool temperatures than were the i n d i v i d u a l blossoms of the com-mercial v a r i e t i e s . ( 3 ) The study on pollen formation i n the d i f f e r e n t l i n e s grown at cool temperatures showed that meiosis was r e l a t i v e l y normal i n the pollen mother c e l l s and that the pollen degenerated p r i o r to anthesis. ( 4 ) A much higher.percentage of Puck pollen than Bonny Best pollen was able to germinate at cool temperatures and f r u i t set i n Bonny Best at these temperatures was l a r g e l y parthenocarpic. These results show that Puck has useful c h a r a c t e r i s t i c s which contributed to f r u i t set at cool temperatures. These c h a r a c t e r i s t i c s could be u t i l i z e d i n a plant breeding pro-gram to improve f r u i t set i n desirable commercial v a r i e t i e s and thus, extend the season and area of tomato production i n Canada. -73-APPENDIX Analysis of data for Table 13 Blossom production u n t i l June 28 Row 1 Row 2 Row 3 Row 4 Row 5 Total Block 1 A 74 E 38 C 21 B 12 D 29 174 Block 2 B 14 C 22 D 42 E 22 A 65 165 Block 3 C 36 A 74 B 8 D 38 E 18 174 Block 4 D 42 B 11 E 38 A 60 C 26 177 Block 5 E 28 D 38 A 76 C 18 B 7 167 Total 194 183 185 150 145 857 Variety Total Mean A - Puck 349 69.8 B - Bonny Best 52 10.4 C - 498 123 24.6 D - 498 x Puck 189 37.8 E - Puck X 498 144 28.8 Analysis oi ' variance Source S.S. D.F. Mean Square F Required F Total 10, 707.04 24 5* 1% Variety 9,840.24 4 2,460.06 65.79 3.26 5.41 Block 21.04 4 5, .26 Row- 397.04 4 99.26 Error 448.72 12 37.39 L.S.D. between v a r i e t y means at odds of 19:1 i s 8.41 L.S.D. between variety means at odds of 99:1 i s 11.79. -74-F r u i t set u n t i l June 28 Row 1 Row 2 Row 3 Row 4 Row 5 Total Block 1 A 9 E 2 C 0 B 0 D 3 14 Block 2 B 0 G 0 D 6 E 0 A 12 18 Block 3 C 0 A 5 B 0 D 4 E 0 9 Block 4 D 11 B 0 E 3 A 4 C 1 19 Block 5 E 1 D 12 A 10 C 0 B 0 23 Total 21 19 19 8 16 83 Variety Total Mean A - Puck 40 8.0 B - Bonny Best 0 0.0 C - 498 1 .2 D - 498 x Puck 36 7.2 E - Puck x 498 6 1.2 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 431.44 24 5% 1% Variety 311.04 4 77.76 12.17 3.26 5.41 Block 22.64 4 5.66 Row 21.04 4 5.26 Error 76.72 12 6.39 L.S.D, between var i e t y means at odds of 19:1 i s 3.49 L.S.D. between var i e t y means at odds of 9 9 s l i s 4.89. -75-Blossom production u n t i l July 18 Row 1 Row 2 Row 3 Row 4 Row 5 Total Block 1 A 212 E 159 C 147 B 95 0 135 748 Block 2 B 86 C 137 D 149 E 133 A 240 745 Block 3 C 176 A 226 B 86 D 145 E 156 789 Block 4 D 143 B 99 E 166 A 244 C 134 786 Block 5 E 177 D 164 A 243 C 140 B 95 819 Total 794 785 791 757 760 3887 Variety Total Mean A - Puck 1165 233 B - Bonny Best 461 92.2 C - 498 734 146.8 D - 498 x Puck 736 147 .2 E - Puck x 498 791 158.2 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 54,394.24 24 5% 1% Variety 50,825.04 4 12,706.26 59.49 3.26 5.41 Block 770.64 4 192.66 Row .247.44 4 61.86 Error 2,551.12 12 212.59 L.S.D. between variety means at odds of 19:1 i s 20.10 L.S.D. between variety means at odds of 99:1 i s 28.17. -76-F r u i t set u n t i l July 18 Row 1 Row 2 Row 3 Row 4 Row 5 Total Block 1 A 41 E 51 C 30 B 26 D 43 191 Block 2 B 43 C 47 D 50 E 47 A 79 266 Block 3 C 45 A 28 B 28 D 41 E 60 202 Block 4 D 50 B 41 E 58 A 66 C 49 264 Block 5 E 39 D 46 A 68 C 43 B 22 218 Total 218 213 234 223 253 1141 Variety Total Mean A - Puck 282 56.4 B - Bonny Best 160 32.0 C - 498 214 42.8 D - 498 x Puck 230 46.0 E - Puck x 498 255 51.0 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 4,409.76 24 5% 1% Variety 1,693.76 4 423.44 3.31 3.26 5.41 Block 976.96 4 244.24' 1.91 Row 202.16 4 50.54 Error 1,536.88 12 128.03 L.S.D, between variety means at odds of 19:1 i s 15.60 L.S.D. between variety means at odds of 99:1 i s 21.83. -77-Blossom p r o d u c t i o n u n t i l J u l y 31 Row 1 Row 2 Row 3 Row 4 Row 5 T o t a l B lock 1 A 286 E 255 C 252 B 165 D 214 1172 B lock 2 B 178 C 254 D 231 E 240 A 293 1196 B lock 3 (3 ' -330 A 315 B 177 D 239 E 238 1299 B lock 4 D 218 B 169 E 283 A 307 C 218 1195 B lock 5 E 290 D 249 A 294 C 253 B 186 1272 T o t a l 1302 1242 1237 1204 1149 6134 V a r i e t y T o t a l Mean A - Puck 1495 299-0 B - Bonny Best 875 175.0 C - 498 1307 261.4 D - 498 x Puck 1151 230.2 E - Puck x 498 1306 261.2 A n a l y s i s o f Va r i ance Source S .S . D .F . Mean Square F Requ i r ed F T o t a l 53 ,625.76 24 5% 1% V a r i e t y 42 ,828.96 4 10 ,707 .24 29.33 3.26 5.41 B lock 2 ,443.76 4 610.94 Row 2 ,512.56 4 628.14 E r r o r 5,840.48 12 486.71 L . S . D . between v a r i e t y means a t odds of 19:1 i s 30.41 L . S . D . be tween-var i e t y means a t odds o f 99:1 i s 42.55. -78-F r u i t set u n t i l July 31 Row 1 Row 2 Row 3 Row 4 Row 5 Total Block 1 A 131 E 137 C 95 B 52 D 125 540 Block 2 B 53 C 90 D 117 E 118 A 150 528 Block 3 C 106 A 107 B 43 D 119 E 148 523 Block 4 D 98 B 57 E 167 A 171 C 82 575 Block 5 E 110 D 113 A 163 C 66 B 58 510 Total 498 504 585 526 563 2676 Variety A - Puck B - Bonny Best C - 498 D - 498 x Puck E - Puck x 498 Total 722 263 439 572 680 Mean 144.4 52.6 87.8 114.4 136.0 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 34,330.96 24 5% 1% Variety 28,112.56 4 7,028.14 18.37 3.26 5.41 Block 488.56 4 122.14 Row 1,138.96 4 284.74 Error 4,590.88 12 382.57 L.S.D. between variety means at odds of 19:1 i s 26.97 L.S.D. between variety means at odds of 99:1 i s 37.79. -79-Fruit set u n t i l August 21 Row 1 Row 2 Row 3 Row 4 Row 5 Total Block 1 A 160 E 267 C 156 B 141 D 203 927 Block 2 B 115 C 148 D 242 E 269 A 156 930 Block 3 C 173 A 114 B 120 D 216 £ 219 842 Block 4 D 200 B 150 £ 238 A 174 G 158 920 Block 5 £ 273 D 215 A 147 C 172 B 160 967 Total 921 894 903 972 896 4586 Variety Total Mean A - Puck 751 150.2 B - Bonny Best 686 137.2 C - 498 807 161.4 D - 498 x Puck 1076 215.2 E - Puck x 498 1266 253.2 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 55,322.16 24 5% 1% Variety 48,019.76 - 4 .12,004.94 30.14- 3.26 5.41 Block 1,680.56 4 420.14 Row 841.36 4 210.34 Error 4,780.48 12 398.37 L.S.D, between variety means at odds of 19:1 is 27.51 L.S.D. between variety means at odds of 99:1 i s 38.49. -80-Analysis of data for Table 14 Ripe f r u i t u n t i l September 11 Row 1 Row 2 Row 3 Row 4 Row 5 Total Block 1 A 16 E 29 C 39 B 33 D 39 156 Block 2 B 36 C 49 D 34 E 28 A 44 191 Block 3 C 42 A 25 B 28 D 38 E 50 183 Block 4 D 35 B 46 E 52 A 29 C 46 208 Block 5 E 33 D 37 A 37 C 47 B . 19 173 Total 162 186 190 175 198 911 Variety Total Mean A - Puck 151 30.2 B - Bonny Best 162 32.4 G - 498 223 44.6 D - 498 x Puck 183 36.6 E - Puck x 498 192 38.4 Analysis of variance Source S.S. D.F. Mean Square F Required F Total 2,120.16 24 5% 1% Variety, 628.56 4 157.14 1.83 3.26 5.41 Block 302.96 4 75.74* Row 156.96 4 39.24 Error 1,031.68 12 85.97 L.S.D. between v a r i e t y means at odds of 19:1 i s 12.77 L.S.D. between var i e t y means at odds of 99:1 i s 17.90. -81-LITERATURE CITED 1. Anonymous. Si x t y - s i x t h annual report of the New York State Agr. Expt. Sta. 1947* 2. Bonn, G. N. A genetic difference i n pollen tube growth i n the tomato. Report of the Tomato Genetics Cooperative No. 5. 1955. 3« Boswell, V. R. Descriptions of types of p r i n c i p a l American v a r i e t i e s of tomatoes. U.* S„ Dept.. Agr.. .Misc. Pub. 160. 1933. 4. Bowser, P. H. The Early Chatham tomato. Quart. B u l l . Mich. Agr. Expt. Sta. 25:254-248. 1943-5. Bouquet, A. G. B. An analysis of the character of the inflorescence and f r u i t habit of some v a r i e t i e s of greenhouse tomatoes. Cornell Univ. Agr. Expt. Sta. Mem. 139. 1932. 6. Brown, A. G. Personal communication to Dr. C. A. Hornby, January 31, 1955. 7. Brown, S. W. The structure and meiotic behavior of the d i f f e r e n t i a t e d chromosomes of tomato. Genet. 34:437-461. 1949. 8. Buckholtz, J. J. The dissection, staining and mounting of styles i n the study of pollen tube d i s t r i -bution. Stain Tech. 6:13-24. 1931. 9. Burk, E. F. The role of p i s t i l length i n the develop-ment of forcing tomatoes. Proc. Amer. Soc. Hort. S c i . 26:239-240. 1929. 10. Calvert, A. Temperature and truss size i n tomatoes. Grower 39:524-525. 1953-11. Cochran, H. L. Some factors influencing growth and f r u i t setting i n the pepper (Capsicum f r u t e s -cens L . ) . Cornell Univ. Agr. Expt. Sta. Mem. 190. 1936.. 12. Crane, M. B. Thirty-ninth annual report of the John Innes Hort. Inst. 1948. -82-13. Emsweller, S. L. and P. B r i e r l e y . E f f e c t s of high temperature on metaphase pair i n g i n Li l i u m  longiflorum. Bot. Gaz. 105:49-57. 1943. 14. F r a z i e r , W. A. A variety with the unusual a b i l i t y to set f r u i t at low temperatures. Report of the Tomato Genetics Cooperative No. 1. 1951. 15. Goodspeed, T. H. and P. Avery. Trisomic and other types i n Nicotiana s y l v e s t r i s . J. Genet. 38: 382-458. 1939. 16. Heydecker, W. A labour-saving tomato. Grower 29: 469. 1948. 17. Howlett, F. S. The effect of carbohydrate and n i t r o -gen deficiency upon microsporagenesis and the development of the male gametophyte i n the tomato (Lycopersicon esculentum). Amer. Bot. 50:767-803^1936. 18. Howlett, F. S. The modification of flower structure by environment i n v a r i e t i e s of Lycopersicon  esculentum. J. Agr. Res. 53:79-117. 1939. 19. Johnson, S. P. and W. C. H a l l . Vegetative and f r u i t -ing responses of tomatoes to high temperature and l i g h t i n t e n s i t y . Bot. Gaz. 114:449-460. 1953 -20. Judkins, W. P. Time involved i n pollen tube extension through style and rate of f r u i t growth i n tomato (Lycopersicon esculentum M i l l . ) . Proc. Amer. Soc. Hort. S c i . 37:891-894. 1939. 21. Larson, R. E. and S. Paur. The description and i n h e r i -tance of a f u n c t i o n a l l y s t e r i l e mutant i n tom-ato and i t s probable value i n hybrid tomato seed production. Proc. Amer. Soc. Hort,. Sql.52:355-364. 1948. 22. Learner, E. N. and S. H. Wittwer. Some eff e c t s of photoperiodicity and thermoperiodicity on veget-ative growth, flowering and f r u i t i n g of the tomato. Proc. Amer. Soc. Hort. S c i . 61:373-380.3955. 23. Leopold, A. C. and F. F. Scott. Physiological factors in tomato f r u i t set. Amer. J. Bot. 39:310-317. 1952. -83-24. Lesley, J. W. and M. M. Lesley. Unfruitfulness i n the tomato caused by male s t e r i l i t y . J . Agr. Res. 58:621-630. 1939. 25. Lesley, M. M. and J. W. Lesley. Parthenocarpy i n a tomato d e f i c i e n t for a part of a chromosome and i n i t s aneuploid progeny. Genet. 26:374-386. 1941. 26. Lewis, D. Some factors a f f e c t i n g flower production i n the tomato. J. Hort. S c i . 28:207-219. 1953. 27. L i , H. W., W. K. Pao and G. H. L i . Desynapsis i n the common wheat. Amer. J . Bot. 32:92-101. 1945. 28. Maheshwari, P. An introduction to the embryology of angiosperms. McGraw-Hill. New York. 1950. 29. Nitsch, F. Growth and development i n v i t r o of ex-cised ovaries. Amer. J. Bot. 38:566-576. 1951. 30. Osborne, D. J. and F. W. Went. Climatic factors i n -fluencing parthenocarpy and normal f r u i t set i n tomatoes. Bot. Gaz. 114:312-323. 1953. 31. Pao, W. K. and W. H. L i . Desynapsis and other abnor-malities induced by high temperatures. J. Genet. 48:297-310. 1948. 32. Richardson, R. W. and T. M. Currence. Genetic effects of reduced f e r t i l i z a t i o n i n tomato flowers. Proc. Amer. Soc. Hort. S c i . 62:449-458. 1953.. 33« Rick, C. M. A survey of the cytogenetic causes of unfruitfulness i n tomato. Genet. 30:347-362. 1945-34. Rick, C. M. The development of s t e r i l e ovules i n Lycopersicon esculentum M i l l . Amer. J. Bot. 33:250-256. 1946. 35. Sax, K. Effe c t of variations i n temperature on nuclear and c e l l d i v i s i o n i n Tradescantia. Amer. J . Bot. 24:218-225. 1937. 36. Schneck, H. W. P o l l i n a t i o n of greenhouse tomatoes. N. Y. Agr. Expt. Sta. B u l l . 470. 1928. -84-37» Smith, 0. Relation of temperature to anthesis and blossom drop of the tomato together with a h i s t o l o g i c a l study of the p i s t i l s . J. Agr. Res. 44:183-190. 1932. 38. Smith, 0. P o l l i n a t i o n and l i f e - h i s t o r y studies of the tomato (Lycopersicon esculentum M i l l . ) Cornell Univ. Agr. Expt. Sta. Mem. 184. 1935. 39* Soost, R. K. Comparative cytology and genetics of asynaptic mutants i n Lycopersicon esculentum M i l l . Genet. 34:410-434. 1951. 40. Went, F. W. Plant growth under controlled conditions. II . Thermoperiodicity i n growth and f r u i t i n g of the tomato. Amer. J . Bot. 31:135-150. 1944. 41. Went, F. W. and L. Cosper. Plant growth under con-t r o l l e d conditions. 71. Comparison between f i e l d and air-conditioned greenhouse culture of tomatoes. Amer. J. Bot. 32:643-654. 1945. 42. White, H. E.. Observations of the effect of nitrogen and potassium on the f r u i t i n g of the tomato. Ann. Appl. B i o l . 25:20-49. 1938. 43» Yeager, A. F. The Victor tomato. Quart. B u l l . Mich. Agr. Expt. Sta. 23:3-6. 1940. 44. Z i e l i n s k i , Q. B. Fasciation i n Lycopersicon. I. Genetic analysis of dominance modification. Genet. 33:404-428, 1948. 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0106363/manifest

Comment

Related Items