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A biological method for the determination of turfgrass reserves Marx, Victor Ferenc 1963

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A BIOLOGICAL METHOD FOR THE DETERMINATION OF TURFGRASS RESERVES by VICTOR F. MARX B.S.A. University of B r i t i s h Columbia, 1961 A Thesis Submitted i n P a r t i a l F ulfillment of the Requirements f o r the Degree of Master of Science in Agriculture in the Di v i s i o n of Plant Science V/e accept t h i s thesis as conforming to the standard quired from candidates f o r the degree of Master of Science The University of B r i t i s h Columbia December, 1963 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that per-m i s s i o n f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s representatives.* I t i s understood that, copying or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n p e r mission. Department of The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada. Date [ 7 - \"lt> A B S T R A C T A b i o l o g i c a l m e t h o d f o r t h e m e a s u r e m e n t o f s o d r e s e r v e s was d e v e l o p e d . A t o o l was c o n s t r u c t e d t o o b t a i n s o d c o r e s o f 4" d i a m e t e r a n d 4 " d e e p . The c o r e s w e r e t a k e n f r o m l a w n s c o n t a i n i n g l o c a l b e n t g r a s s e s , b l u e -g r a s s e s , f e s c u e s a n d r y e g r a s s e s , a n d f r o m p u t t i n g g r e e n s c o m p o s e d o f l o c a l b e n t g r a s s s t r a i n s . The c o r e s w e r e k e p t i n a d a r k c h a m b e r . The e t i o l a t e d g r a s s was c l i p p e d p e r i -o d i c a l l y u n t i l t h e r e s e r v e s i n t h e c o r e s became e x h a u s t e d . The o v e n d r y w e i g h t o f c l i p p i n g s f r o m a u n i t c o r e a r e a , t h e s o d r e s e r v e i n d e x , was u s e d a s a m e a s u r e o f r e s e r v e s . The s o d r e s e r v e i n d e x was f o u n d t o v a r y w i t h s p e c i e s and v a r i e t i e s , s o i l c o n d i t i o n s , management p r a c t i c e s , amoun t o f s o l a r r a d i a t i o n , w e a r a n d c o m p a c t i o n , a n d s e a s o n a l c h a n g e s . Summer d o r m a n c y d e p r e s s e d t h e l e v e l o f s o d r e -s e r v e s . I t a p p e a r e d t h a t p h o t o p e r i o d may p l a y some r o l e i n c o n t r o l l i n g summer d o r m a n c y . T h e t u r f q u a l i t y was d i r e c t l y r e l a t e d t o t h e amoun t o f r e s e r v e s ; t h e r e f o r e , t h e s o d r e s e r v e i n d e x may b e u s e d a s one o f t h e o b j e c t i v e m e a s u r e o f t u r f q u a l i t y . The l o c a l i z a t i o n o f r e s e r v e s i n t h e s o i l p r o f i l e v a r i e d s l i g h t l y w i t h t h e s p e c i e s u s e d , b u t t h e r e s u l t s i n d i -c a t e d t h a t o n l y t h e u p p e r one i n c h o f t h e s o i l h o r i z o n h a s a m a j o r r o l e a s a s t o r a g e z o n e f o r u n d e r g r o u n d r e s e r v e s . V. ACKNOWLEDGEMENTS I wish to express my gratitude to Dr. V.C. Brink, Chairman of my thesis com-mittee, for his d i r e c t i o n throughout t h i s study, and also to the other committee members: Dr. E.H. Gardner, Dr. C.A. Hornby, Dr. N.A. McLean, Dr. J.W. N e i l l , Dr. J.J. Richter, and Mr. H. Vaartnou, a l l of the University of B r i t i s h Columbia, Vancouver. Thanks are accorded Mr. D. Clark, the late Mr. G. Croft, Mr. W. McLean, Mr. A . McLeod, Mr. V,'. Rees, and Mr. R. Scott, golf course superintendents of the Van-couver, B.C. area, for t h e i r cooperation. I should l i k e to thank the B r i t i s h Columbia Sugar Refinery Company Limited and the Royal Canadian Golf Association fo r f i n a n c i a l support. i i i . TABLE OF CONTENTS Page I. INTRODUCTION 1 I I . REVIEW OF THE LITERATURE 4 I I I . INVESTIGATIONS 61 A. Materials and methods 61 1. The t u r f coring instrument 61 2. Sampling i n the f i e l d 69 3. Treatments following sampling 70 4. Harvesting of e t i o l a t e d grass 71 5. Drying of grass clippings 72 B. Observations and res u l t s 72 (1) 72 (2) 74 (3) 75 (4) 76 (5) 78 (6) 79 ( a ) 80 (b) 83 (c) 85 (d) , 88 (7) 92 (8) 96 (9) 99 (10) 101 103 IV. DISCUSSION V. SUMMARY AND CONCLUSIONS H g VI. BIBLIOGRAPHY 120 VII. APPENDIX A B C D E F G H I J K L Ni N 137 137 138 139 140 141 143 145 147 149 152 154 154 155 i v . TABLES AND FIGURES Page A. TABLES I. 12 I I . 74 I I I . 76 IV. 78 V. 82 •VI. 82 VII. 84 VIII. 85 IX. 88 X. 88 XI. 90 XII. 91 XIII. 94 XIV. 95 XV. 98 XVI. 98 B. FIGURES 1 63 2 64 3 65 4 66 5 67 6 91a 7 100 I IRTjiODUCTIpJi Turfgrass quality assessment i s d i f f i c u l t because the c r i t e r i a used are many and s u b j e c t i v e . Colour, vigour, u n i f o r m i t y , r e s i s t a n c e to wear and compaction, pest and disease r e s i s t a n c e , and drought r e s i s t a n c e , may a l l , i n some way, r e l a t e to t u r f g r a s s q u a l i t y . There i s one approach to q u a l i t y assessment which r e l a t e s g e n e r a l l y to a l l of the aforementioned c r i t e r i a , v i z . the q u a n t i t y of "reserve food" m a t e r i a l s i n the root and stubble. Because of d i f f i c u l t i e s i n d i r e c t l y determining reserves, which are l a r g e l y carbo-hydrate i n nature, t h e i r determination i s seldom attempted. The s t u d i e s reported here were undertaken with a view t o e x p l o r i n g an i n d i r e c t method f o r determining reserves and hence another method f o r a s s e s s i n g t u r f q u a l i t y . The need f o r o b j e c t i v e and q u a n t i t a t i v e methods f o r assessing t u r f q u a l i t y i s evident. Simple y i e l d determinations are not as u s e f u l i n t u r f g r a s s e v a l u a t i o n as f o r most agronomic and h o r t i c u l t u r a l crops. Colour determination a l s o , although very useful, i s not without d i f f i c u l t y . Healthy s t r a i n s and species of t u r f g r a s s vary widely i n "greenness", i n h e r e n t l y , and from season t o season; furthermore, what i s a " p l e a s i n g green" to some person may not be so t o another. It cannot be denied, however, that colour r e f l e c t s t u r f h e a l t h t o a remarkable 2 d e g r e e ; d i s e a s e d p l a n t s o f t e n show v x r e s c e n c e o r c h l o r o s i s , and t h e n u t r i e n t s t a t u s o f t h e t u r f g r o w t h m e d i a i s o f t e n r e f l e c t e d i n t h e c o l o u r o f t h e grass„ N o n e t h e l e s s , c o l o u r i s d i f f i c u l t t o s p e c i f y and a t t e m p t s t o m e a s u r e i t q u a n t i -t a t i v e l y h a v e n o t b e e n w h o l l y s u c c e s s f u l . F o r some d e c a d e s i t h a s b e e n r e c o g n i z e d t h a t t h e h e a l t h o f a. p e r e n n i a l g r a s s i s v e r y well r e f l e c t e d i n t h e " f o o d r e s e r v e s " o f i t s r o o t s and s t u b b l e . D i s e a s e s , p e s t s , i m p r o p e r c u t t i n g p r a c t i c e s , l o w s o i l f e r t i l i t y , and s o i l c o m p a c t i o n t e n d t o r e d u c e p h o t o s y n t h e s i s and t h e r e s e r v e c a r b o h y d r a t e s i n r o o t and. s t u b b l e o f t u r f o A l t h o u g h t h e r e i s g e n e r a l a c k n o w l e d g e m e n t o f t h e v a l i d i t y o f t h i s o b s e r v a t i o n , a s h a s b e e n p o i n t e d o u t a b o v e , t h e d e t e r m i n a t i o n o f c a r b o h y d r a t e r e s e r v e s i n t u r f i s f r a u g h t with d i f f i c u l t y . The r e m o v a l o f i n t a c t r o o t s f r o m t h e s o i l p r i o r t o a s s a y f o r r e s e r v e c a r b o h y d r a t e , i s a v i r t u a l impossibility„ Even when exhumed w i t h g r e a t c a r e a v e r y l a r g e p e r c e n t a g e o f t h e r o o t i s l o s t . M o r e o v e r , a c e r t a i n p e r c e n t a g e o f t u r f g r a s s r o o t g r a d u a l l y c e a s e s t o f u n c t i o n and d i e s e a c h y e a r ; t h e l i v i n g o r a c t i v e r o o t f r a c t i o n c a n n o t be r e a d i l y d i s t i n g u i s h e d f r o m t h e d e a d r o o t s . S i n c e d i r e c t d e t e r m i n a t i o n o f t u r f g r a s s r e s e r v e s p r e s e n t s many d i f f i c u l t i e s , s e v e r a l w o r k e r s h a v e s o u g h t t o a s s a y them I n d i r e c t l y . R e c e n t l y , B u r t o n and J a c k s o n (1962) h a v e s t i m u l a t e d i n t e r e s t a g a i n i n i n d i r e c t m ethods b y s u c c e s s f u l l y u s i n g t h e d r y m a t t e r p r o d u c e d by 5 s o u t h e r n g r a s s e s g rown w i t h o u t 3 l i g h t as a r e f l e c t i o n of t h e i r reserves. To apply t h e i r approach to t u r f of other species and under other conditions seemed, desirable and t h i s i s the object of these studies. B a s i c a l l y simple, the method r e s t 3 on the assumptions that, (a) following mowing, root groxvth of t u r f ceases and carbo-hydrate reserves are u t i l i z e d i n the production of new a e r i a l growth which can be readily harvested, and (b) t u r f placed i n darkness, or i n weak l i g h t , but under conditions standard for growth, except f o r l i g h t , w i l l produce an amount of a e r i a l dry matter which r e f l e c t s the reserves i n the t u r f . 4 I I . RSVIEV; OF THE LITERATURE D e f i n i t i o n of Reserves The d e f i n i t i o n s used i n the l i t e r a t u r e on reserve substances i n plants lack uniformity and s p e c i f i c i t y . The reader finds such terms as "carbohydrate reserves", "reserve carbohydrates", "reserve materials", "reserve substances", "reserve food", "food reserves", "storage carbohydrates", and so on, used interchangeably. Several authors o f f e r d e f i n i t i o n s depicting the meaning of some of these terms. That carbohydrates are the prime reserves i s generally acknoxvledged. Weinmann (194c) defines "reserve substances" as: "organic materials elaborated by the plant, and stored at certain times i n the more permanent organs of the plant body, to be u t i l i z e d at a l a t e r stage by the plant as a source of energy or as a bui l d i n g material." Troughton (1957) refers to Thomas (1947) i n defining "reserve substances" as follows: "before a substance can be c l a s s i f i e d as reserve food i t must be shown that a preliminary period of accumulation is followed by a. period i n which t h i s substance i s maintained i_n s i t u at a r e l a t i v e l y high concen-t r a t i o n , and that l a t e r , i n association with physiological processes taking place in the immediate v i c i n i t y or elsewhere, the concentration diminishes." 5 Loomis (1932) d i s t i n g u i s h e s between " a c t i v e " and "storage" forms of carbohydrates. As P r i e s t l e y (I962) points out, however, these terms should not be a p p l i e d too r i g i d l y because the l i v i n g plant i s a dynamic e n t i t y i n which r a p i d conversions may occur i n both d i r e c t i o n s between " a c t i v e " and "storage" compounds. Most authors imply carbohydrates, u s u a l l y s o l u b l e forms of carbohydrates, when they use one of the above terms, though the exis t e n c e of non-carbohydrate reserve food substances i s a l s o recognized. The p a r t i c u l a r groups of organic compounds which c o n s t i t u t e the "carbohydrate reserves" of grasses w i l l be de a l t with l a t e r . Studies Revealing the Importance of Reserve Carbohydrates i n  Plants The i n v e s t i g a t i o n of reserve carbohydrates i n plan t s owes much to the fundamental work of Kraus and K r a y b i l l (1913). These authors concluded from chemical, p h y s i o l o g i c a l , and h i s t o l o g i c a l s t u d i e s of the tomato pl a n t t h a t : "the a v a i l a b l e c a rbohydrates...constitute as much of a l i m i t i n g f a c t o r i n growth as the a v a i l a b l e n i t r o g e n and moisture supply. IVhen the opportunity f o r carbohydrate manufacture w i t h i n the plant i t s e l f i s g r e a t l y reduced, or e l i m i n a t e d . . . v e g e t a t i o n i s decreased. Oraber et a l . (1927) were among the f i r s t who studied the reserve carbohydrates of forage p l a n t s . In accordance with Kraus and K r a y b i l l (1913) they found that the p h y s i c a l , chemical, and b i o l o g i c a l responses of a l f a l f a , timothy, bluegrass, and red top, i n d i c a t e that the l a c k of carbohydrate reserves i s a growth l i m i t i n g f a c t o r i n p e r e n n i a l herbaceous p l a n t s . Later Graber (1931) st a t e d t h a t : "the s u r v i v a l of economic p l a n t s . . . [is]dependent upon many i n t e r - r e l a t e d f a c t o r s , but organic reserves are among the most important. Although Graber acknowledged that grasses i n lawns, g o l f courses and pastures may e x i s t f o r many years under management which i s not conducive to the accumulation and maintenance of high l e v e l s of r e s e r v e s , nevertheless, he maintained that t h e i r c a p a c i t y f o r s u r v i v a l i s g r e a t l y reduced under such c o n d i t i o n s , and " a r t i f i c i a l " means must be employed to ensure t h e i r s u r v i v a l . " A r t i f i c i a l " i n t h i s instance would include such items as overwatering and very frequent f e r t i l i -z a t i o n of g o l f greens and home lawns. Graber (1931) reasoned t h a t the low l e v e l of reserves may reduce the a b s o r p t i v e c a p a c i t y of grass and may increase i t s s u s c e p t i b i l i t y to drought, winter i n j u r y , weed encroachment i n s e c t i n j u r y and other hazards. He warned that such secondary e f f e c t s o f t e n i n t e n s i f y the i n f l u e n c e of low reserves on the p r o d u c t i v i t y of the p l a n t s , r e s u l t i n g i n f u r t h e r d i m i n u t i o n of t h e i r reserve materials . Graber et a l . (1927) found that the s u s c e p t i b i l i t y of a l f a l f a t o w i n t e r i n j u r y i s increased by low percentages of dry matter and low concentrations of carbohydrate and n i t r o g e n reserves i n the roots at ivint e r dormancy. 7 Greathouse and Stewart {1934, 1936/a, 1936/b), working with medium red clover, found that winter hardiness i s associated with a high l e v e l of food storage. The findings of other workers, notably those of V a s s i l i e v and V a s s i l i e v (1936), McCarty (1933), L e v i t t and Siminovitch (1940), KcCarty and Price (1942), and Julander (1945), provide further evidence that winter hardiness in plants is associated with the accumu-l a t i o n of carbohydrate reserves. Experiments which exposed plants to f r o s t hardening resulted i n the accumulation of carbohydrates. Julander (1945) postulated that since the hardening process, when plants are preparing for drought, i s e s s e n t i a l l y the same as i n f r o s t hardening, carbohydrate accumulation should also be correlated with drought resistance. Evidence which v e r i f i e s this can be found i n the works of Rosa (1921), Spoehr (1919), V a s s i l i e v and V a s s i l i e v (1936), and Julander (1945). Julander exposed grasses to a temperature of 4 S 0 C and found that they survived when they had previously been hardened to dry conditions and had not been severely clipped. Both of these conditions were conducive to the accumulation of carbohydrate reserves. From the work of the previously mentioned authors and from his own observations Julander concludes that heat resistance i s a measure of drought resistance, and that large accumulations of c o l l o i d a l carbohydrates, es p e c i a l l y levulosans, i s associated with drought resistance. 8 There i s a d i f f e r i n g opinion, however, regarding the cor r e l a t i o n between carbohydrate content and heat, cold and drought resistance. C a r r o l l (1943) studied 15 turfgrass species, taking clippings from the least and most cold and drought hardy species; simple sugar, t o t a l nitrogen, and bound water were determined. Data on sugars were found to be unreliable as c r i t e r i a of the r e l a t i v e hardiness of tu r f species to heat, cold and drought. A notable omission in t h i s work i s the f a i l u r e to determine "available" carbohydrates such as the fructosans. The spring regrowth of grasses when l i g h t and temperature conditions are not favourable to photosynthesis is largely dependent upon the reserve food material accumulated i n the grass plant's storage organs at the end of the previous season. Troughton (1957) i n his review recorded that 70 - 75 percent of the carbohydrate reserves produced annually may be used i n the formation of spring herbage and new root growth. While most authors have found c o r r e l a t i o n betx\*een reserve carbo-hydrate content and spring regrowth of grasses, Baker ( i 9 6 0 ) did not f i n d d i r e c t c o r r e l a t i o n between the stubble carbohydrate content of cocksfoot i n the autumn and i n the regrowth of spring. It i s probably worth noting, however, that photosynthesis was ac t i v e l y proceeding during much of Baker's experimental period and could conceivably have been an uncontrolled factor of importance i n his t r i a l s . Graber (19?-9) found that bluegrass pastures xvith high Q reserves were less severely injured by white grubs, a common pest of midwestern United States s o i l s , than pastures with low reserves. V/eed populations, also, i n his experiments, were ten times higher in pastures with low reserves than in pastures with high reserves. The s u r v i v a l value of reserve carbohydrates of plants growing under environmental conditions which may be termed "extreme", "abnormal", or "adverse" has been demonstrated repeatedly and i s one fact which stands out c l e a r l y i n a large controversial l i t e r a t u r e r e l a t i n g to cold resistance, drought resistance, weed tolerance, and insect and disease tolerance of plants. Studies Concerning the Chemical Nature of Reserves. Various authors consider the following carbohydrates and carbohydrate groups as reserve substances: simple sugars, dextrins, starch, c e l l u l o s e , hemicelluloses, and fructosan. There are authors who dispute the role some of these substances play as reserve food. Albert (1927), Graber et a l . (1927), and Leukel (1927) l i s t sugars, dextrins, starch and hemicelluloses as available carbohydrates i n a l f a l f a and forage grasses. McCarty (1935), (193$), from his study of several range grasses concludes that sugars and starches are the most important storage foods. He states that the acid hydrolizable hemicellulose has only a stru c t u r a l r o l e . Weinmann (19A-3) also believes that the more 1 0 complex polysaccharides, such as pentosans, hemicelluloses, and true c e l l u l o s e s are s t r u c t u r a l materials. Similar opinions are held by Brown ( 1 9 4 3 ) , and Sul l i v a n and Sprague (1953). Other authors, besides the already mentioned Albert, Graber, and Leukel, are of the opinion that hemicellulose may, at times, act as a reserve food. This view i s held by Leukel and Coleman ( 1 9 3 0 ) who base t h e i r opinion on t h e i r study of Pa spa I. ura notatum. I-'orosov ( 1 9 3 9 ) also believed i n the u t i l i z a t i o n of hemicellulose as reserve food. J e f f e r i e s (1916), and Arber ( 1 9 3 4 ) state that c e l l u l o s e acts as a reserve in Molinia caerulea. Sampson and J-icCarty ( 1 9 3 0 ) place sucrose and polysaccharides before monosaccharides as the more important accumulation products i n Stipa pulchra. Morosov ( 1 9 3 9 ) also finds that the disaccharide sucrose i s a more important reserve than the monosaccharides i n three temperate grass species. Rapp (1947) states that i n Sorghum halepense sucrose i s a more important reserve than starch, dextrins or reducing sugars. Weinmann and Reinhold ( 1 9 4 6 ) , on the other hand, f i n d that i n the majority of the 13 South African grasses i n t h e i r study, non-reducing sugars are the p r i n c i p a l reserves. Hany authors regard fructosans as the main food reserve in grasses; other's, however, oppose t h i s view, and the debate i s s t i l l unresolved. De Cugnac ( 1 9 3 1 ) used the presence or absence of fructosan to c l a s s i f y grasses in two groups. The f i r s t group contains fructosan, usually together with sucrose, but without starch. The second includes species 11 which store sucrose with or-without starch, but no fructosan. Of the 3$ species of Gramineae he examined, 23 contained fructosans. Some of these are: Alopecurus ag r e s t i s , Agropyron repens t Agrostis alba, Arrhenatheruin e l a t i u s , A. bulbosum, Dactyiis glomerata, Festuca pratensis, LoMum perenne, and Phleum pratense* The second group with no fructosan includes, among others, Brachypodium pinnaturn, B. sylvaticum r Cynodon dactvlon, Muh.lenbergia s i l v a t i c a . Panic urn stagninum. Sorghum halepense, and Spartina polyst-achya. Reports by Norman (1936), Norman and Richardsonf1937), Archbold (1940), Harper and Ph i l i p s (1943), S u l l i v a n and Sprague (1943), A m i and Pe r c i v a l (1951) point out that fructosan i s the main reserve substance in grasses, vveinmann and Reinhold (1946), on the contrary, report that only i n s i g n i f i c a n t amounts of fructosans occur i n South African grasses, and that non-reducing sugars are the p r i n c i p a l reserves. There may be explanations f o r these apparent contra-dictions,, De Cugnac (1931) pointed out that grasses in cool temperate climates contain fructosans, and the grasses which are adapted to warm regions have no fructosans. Weinmann (194$) implies that the grasses reported as having no fructosan (1946) were warm climate species. Since Weinmann and Reinhold studied roots, they might have overlooked fructosans stored i n other organs of the grasses. In t h e i r study of reserve carbohydrates in orchardgrass, S u l l i v a n and Sprague report fructosan to be the dominant water soluble carbohydrate i n the stubble, and sucrose to be the dominant carbohydrate i n the root. 11a In another paper, S u l l i v a n and Sprague (1943) argue that owing t o imperfect a n a l y t i c a l methods fructosans are often i n c o r r e c t l y reported as d e x t r i n and s t a r c h . In t h e i r o p inion when s t a r c h determination i n grasses i s based on determinations w i t h s a l i v a or other enzymatic reagents i n water s o l u t i o n , f r u c t o s a n may go i n t o s o l u t i o n and hydrolyze i n the subsequent a c i d treatment which of t e n f o l l o w s d i a s t a t i c a c t i o n . In the opi n i o n of these authors: "Carbohydrates r e a d i l y change from one form t o another so that by or d i n a r y methods of a n a l y s i s i t i s impossible t o trace...any p a r t i c u l a r one i n the p l a n t . " L o c a l i z a t i o n of Reserves Carbohydrates are stored i n r o o t s , rhizomes, s t o l o n s , corms, bulbs, stems, l e a f bases, and i n the leaves of the grass. Their r e l a t i v e p r o p o r t i o n may vary w i t h the s p e c i e s , environment and management p r a c t i c e s . Roots and other underground organs, are u s u a l l y g r e a t e r i n s i z e and weight than the a e r i a l part of a p e r e n n i a l herb; they are however on a per gram dry matter b a s i s r e l a -t i v e l y poorer i n reserves than a e r i a l p a r t s . Sprague and S u l l i v a n (195C) give an a n a l y s i s of d i s t r i b u t i o n of carbohydrates i n the bunchgrass orchardgrass, noting t h a t t h i s d i s t r i b u t i o n seems to be t y p i c a l of a l l grasses of s i m i l a r anatomical s t r u c t u r e . ( T a b l e 1). 12 TABLE I. Preliminary Analysis of Orehardgrass to Show  Dis t r i b u t i o n of Carbohydrates in Different Parts of the Plant Sprague and S u l l i v a n (1950) Part of Weight of plant Carbohydrates in % of dry wt. plant part i n % cf wt. Reducing Sucrose Fructosan of entire plant sugars Upper 2/3 14.0 1.4 8.V 7.6 of blades Lower 1/3 12.1 1.2 5.3 22.0 of blades Upper 1/2 9.4 1.9 3 .6 23.7 of stubble Lower 1/2 23.6 0.7 2.6 36.2 of stubble Roots 40.9 1.2 8.9 8.2 Roots are r i c h e r in sucrose than the tops but r e l a -t i v e l y poorer in t o t a l carbohydrate. Since, as the authors point out, over 40 percent of the whole plant's weight i s i n the roots, they contain a large part of the available reserves, esp e c i a l l y of grass grazed or mown. Rhizomes, which are r e a l l y underground stems, of Poa pratensis are reported (Brown (1943) to have a higher percentage of sugars and starch than the roots. Conns and bulbs are found i n certain species of Poa, Meliea, Mo1inla f Festuca, Holcus f Arrhenatherum, Beckmannia, Hordeum. Ehrharta. Phalaris. and Panicurn as reported by Burns (1946). He suggests that these organs in Gramineae are devices 13 f o r ensuring s u r v i v a l over the hot, dry season of the Medi-terranean climate and f o r g i v i n g the grass p l a n t s the much needed food when the growing season recommences; i n a few cases the cold season i s met by the same means. Waters (1915), Wishimura (1922) and Evans (1927) report that the haplocorm of Phleum pratense serves as a storage organ t o provide food f o r growth dur i n g the summer and f o r new growth i n the f o l l o w i n g w i n t e r . J e f f e r i e s (1916) regards the club shaped b a s a l i n t e r -nodes of M o l i n i a caerulea as a storage organ supplying food f o r e a r l y s p r i n g growth. The conns of Arrhenatherum avenaceum are considered by Jenkin (1931) to be the means by which the plant overwinters. The above statement paints a general p i c t u r e of the l o c a l i z a t i o n of reserves i n underground organs, of grasses; a more comprehensive p o r t r a y a l i s given by Weinmann (194$) and Troughton (1957). Stem and l e a f bases, together with the sheaths are often r e f e r r e d to as "stubble". The stubble has more reserve substances on the percentage b a s i s than any other part of the grass. This i s ass o c i a t e d with abundant meristematic t i s s u e s found i n t h i s r e g i o n . Loeb (1924-) and Janse (1925) point out that the meristematic regions make heavy demands on food reserves. Sampson and McCarty (1930) report that food "deposited", polysaccharides mostly, i n the stem bases of S t i p a pulchra i s p r o p o r t i o n a t e l y g r e a t e r than i n the -roots. Jones (1933) p o i n t s out t h a t some s p e c i e 3 of grasses have enlarged l e a f bases which 14 f u n c t i o n as storage organs of food m a t e r i a l s . Sprague and S u l l i v a n (1950) are of the opinion that stubble i s the major storage organ of grasses. I n t h e i r t a b l e , presented p r e v i o u s l y , f r u c t o s a n content appears to be the major reserve food source, and stubble contains more f r u c t o s a n than the r o o t s and tops together. In a l a t e r paper of S u l l i v a n and Sprague (1953) t h i s observation i s repeated. V/aite and Boyd (1953 ) report carbo-hydrates to be more abundant i n stems than i n leaves of grasses. S i m i l a r observations are reported by Baker (1955) and Baker and Garwood (1961). This l a t e r paper records r e s u l t s obtained with cocksfoot. T o t a l s o l u b l e carbohydrates i n roots of cocksfoot di d not exceed 4 percent throughout the season, but i n the herbage reached a maximum of 10 percent, and i n the stubble a maximum of lb 1 percent: f r u c t o s a n i n stubble was 16.6 percent at i t s highest l e v e l . I t i s appropriate t o point out here t h a t major meristematic regions a s s o c i a t e d with regrowth of leaves and with t h e i r movement are lo c a t e d at l e a f bases and are c l e a r l y a s s o ciated with nodal food r e s e r v e s . Troughton (1957) warns against a f a l l a c y which may be encountered when i n t e r p r e t i n g carbohydrate data based on percentages without due account f o r the a c t u a l s i z e or weight of the organ. Most workers study only concentrations which represent r e l a t i v e amounts of carbohydrates. Organs, such as r o o t s , may contain large q u a n t i t i e s of reserves even though the percentage i s low (because of the lar g e s i z e of the root system). 15 The l i t e r a t u r e reviewed raises doubts as to the general v a l i d i t y of a coir;:.only held b e l i e f , that the food storage cf grasses i s located underground. It i s true that there are reserve substances i n underground organs; t h e i r r e l a t i v e importance to those stored above the ground, however, needs to be reassessed. Possibly management practices on sportsturf, home lawns and pastures are too root-oriented. The Seasonal Growth Cycle of Grass and Fluctuations of Reserves. Troughton (1957) and V/einmann (194-6) review the limited l i t e r a t u r e on seasonal variations of root reserves and the seasonal growth cycle of grasses. Troughton l i s t s the following sequence i n the seasonal growth cycle of the root; the i n i t i a t i o n and growth of roots, the decay of old roots, and the use the plant makes of the root as a storage organ f o r food reserves, i n i t i a t i o n and growth have been observed most frequently during the autumn and spring; i n r e l a t i v e l y mild climates i t has also been observed, during the summer and winter. Most root growth occurs in the spring, and ceases completely before flowering. Old roots start to decay during flowering of the grass plant. This cycle functions only under conditions where the grass i s allowed to grow undisturbed. As Sprague and Sullivan (1950) point out, i f the grass i s exposed to periodic d e f o l i a t i o n s , i t undergoes several cycles per year. Aldous (1930 a), studying the r e l a t i o n of organic food reserves in the growth of some Kansas plants of the dryland range, found that i n trie grass Andropogon scoparius food 16 reserves decrease at the beginning of the growing season (May) ; then there was a gradual increase during the late spring and early summer; then followed a decrease at the time of secondary herbage growth. A si m i l a r trend was found by Mcl.lvanie (1942) in Agropyron sp1catum. Stapledon and Milton (1930) reported that the root development of Dactylis glomerata was progressive from A p r i l to September. Sturkie (1930) studied Sorghum  halepense and found that the root stocks developed a f t e r the a e r i a l parts had matured. Sampson and McCarty (1930) reported that the growth cycle of Stipa pulchra i s divided into d e f i n i t e i n t e r v a l s , which are characterized by di f f e r e n t growth rates. Flowering, the development of seed, the deposit of carbohydrates i n the perennial organs, and the maturing of herbage i s the regular sequence. A e r i a l growth was negatively related to food accumulation. During rapid growth the u t i l i z a t i o n of food i n the growth process exceeded i t s a v a i l a b i l i t y , r e s u l t i n g i n a low l e v e l of carbohydrates i n the stem bases and roots. This was c h a r a c t e r i s t i c of spring growth. Later, when the growth rate slowed doxvn, c h a r a c t e r i s t i c a l l y a further accumulation of reserves occurred i n the stem, bases and roots. From the findings of Sampson and McCarty i t follows that food accumulation should take place in raid-summer when herbage growth is very slow indeed. This was not the case, however, i n the rhizomes of Agropyron repens, studied by Arny (1932). This author was unable to f i n d any d i s t i n c t changes in the rhizomes during the summer months. His observation i s 17 confirmed by Weinmann (1947) who noticed only i r r e g u l a r fluctuations of reserves i n the rhizomes of Cynodon dactylon. Brown (1943), on the other hand, noticed accumulation of carbohydrates in the rhizomes of Poa pratensis during the hot weather of late spring and early summer. This, however, was true only f o r plants cut f o r hay, but not f o r those which were mown f o r t n i g h t l y . A reduction i n carbohydrate content of both roots and rhizomes took place during the summer drought, a f a r greater loss occurring in the plants which were i r r i g a t e d than i n those which were not. Brown (1943) found that the period most favorable for carbohydrate accumulation i n the roots was between September and November, and i n trie rhizomes from mid-October to November under Missouri conditions. McCarty (1935) found that the bulk of the carbohydrate foods was produced near the end of the season in Slymus ambiguus and Muhlenberg!a graci 1is , and the accumulation of reserves was completed by mid-September (under Utah conditions). McCarty (193$), and McCarty and Price (1942) studied the growth cycle of Bro_mu.s carinatus and Agropyron  trachycaulum under Utah conditions and reported that there were three inte r v a l s i n adventitious root growth: (1.) Immediately preceeding snow disappearance, (2.) At the conclusion of current seasonal shoot growth, (3.) At the close of snow-free period i n autumn. The growth of herbage and adventitious roots made previously to the disappearance of snow and i n early spring was found to consume approximately 70-75 percent of the sugar and. the starch accumulated during the previous autumn. The carbo-18 hydrate l e v e l was lowest at the time of most active herbage growth, and the maximum was reached i n the autumn when herbage growth ceased. Similar variations were reported by Weinmann (1940), and V'einmann and Reinhold (1946) i n South .African grasses. The general trend i n herbage and root growth observed by these authors was also noted by Mcllvanie (1942) i n Agropyron spicatum. He also reported that the greatest r e l a t i v e amounts of reducing sugars in the roots were associated with rapid, herbage growth. Sucrose reached i t s maximum during d i f f e r e n t i a t i o n . "Reserve polysaccharides" were highest at the rest period p r i o r to secondary growth. Harper and F h i l l i p s (1943), studying the storage organs of timothy i n New Hampshire, found that there was a rapid increase in fructosan content while the flower heads were being formed during June. Then followed a plateau which ended in a s l i g h t decline in October. There were no d i s t i n c t trends i n the variations in glucose, fructose and sucrose content. At the end of winter a great decrease was observed in the concentration of fructosan, and s l i g h t increases were noted i n the percentages of sugars. Rapp (1947) studied the variations of sucrose, reducing sugars, starch and dextrine in young plants of Sorghum halepense. During the early stages of growth metabolic reactions favored the formation of glucose to support the young sprouts. Carbohydrate reserves were depleted before shooting. As the plants developed, sucrose became the dominant carbohydrate and remained well into the growing season. After maturity was reached, the reserves in the top were trans-ported as glucose to the rhizome where i t was reconverted to 19 sucrose f o r winter storage. Baker and Garwood (1961) found marked fluctuations of t o t a l carbohydrates i n the stubble of cocksfoot, and these variations were correlated with seasonal development. Maximum carbohydrate content was obtained i n October. The formation of new roots and the decay of old ones i s related to seasonal growth. Sprague (1933) studied Kentucky bluegrass and c o l o n i a l bentgrass and observed that new roots were formed i n the spring. His results indicate that at least one half of the root system i s generated anew i n spring. After maximum root weight i s reached, root weight i s decreasing at the time of heavy top growth. On Rhode Island, Stuckey (1941) studied the seasonal root growth of 12 species of grasses. I t was formd that in some species the whole root system was regenerated annually with active production of new growth beginning i n October. Growth continued slowly through the winter, then increased rapidly a f t e r the spring thaw i n March, ana reached i t s maximum i n March-April. After mid-June root formation ceased, and then • new roots did not form u n t i l October. Most of the old roots disintegrated soon a f t e r the new roots were formed. In some species, however, only a few r o o t 3 were formed a f t e r spring, and only a small percentage of the old roots died. Similar observations were made by V.'eaver and Zink (1946) i n Nebraska who studied 10 pasture and range grasses and. found that a large proportion of the roots survived one, two, and even three seasons. 20 The c o n f l i c t i n g evidence presented by these authors regarding the dying and decaying of old roots suggests that either there i s difference among grasses i n t h i s regard, depending on genetical factors inherent in the species studied and perhaps depending also on environmental factors, or that perhaps the present methods of studying grass roots are not r e l i a b l e enough to prodiice conclusive evidence concerning the seasonal formation and replacement of roots. Brink (1962) pointed out that observations could be quite unreliable where one is required to d i s t i n g u i s h between l i v i n g , dying and dead roots in a t u r f p r o f i l e . Future research should emphasize the separation of l i v i n g root tissues from dying and dead ones. Ecolog i c a l Factors Influencing, the Accumulation of Organic Reserves in the Grass The Effect of S o i l F e r t i l i t y S o i l f e r t i l i t y is undoubtedly related to the accumu-l a t i o n of reserves i n grasses. Nightingale (1927), i n accordance with Kraus and K r a y b i l l (1913), stated that a r e l a t i v e decrease in nitrogen supply causes carbohydrate accumulation, but further decrease in nitrogen and increase i n carbohydrates makes for the accumulation of nitrogen as protein and. leads to the suppression of vegetation. iveinmann (194c), who reviewed the l i t e r a t u r e on the effects of nutrients and f e r t i l i z e r s on the underground develop-ment of grasses, summarized the findings of Aldous (1930a), Harrison (1931), Willard and KcClure (1932) as follows: 21 "The abundance of nitrogen may, at certain stages of the plant's l i f e cycle or under conditions of severe d e f o l i a t i o n , lead to an increased u t i l i z a t i o n of carbohydrate reserves, and even to the reduction i n root weight. Under conditions of protec-t i o n , on the other hand, the plant w i l l be able to restore i t s reserves... The increase i n t o t a l leaf area, and hence i n t o t a l photosynthetic a c t i v i t y , which is usually associated with improved s o i l f e r t i l i t y , may ultimately re s u l t i n an increased accumulation of reserves and higher root weights. Graber (1931) studied bluegrass reserves under various f e r t i l i z e r and cutting treatments and found that without f e r t i l i z a t i o n bluegrass with "high" reserves produced nearly three times the amount of dry matter obtained from "low" reserve grass. 'With f e r t i l i z a t i o n the y i e l d s from "high" reserve grass were 1.6 times higher than those obtained from low reserve grass. From t h i s Graber concluded that "although the s o i l may be abundantly supplied with mineral nutrients, the plant may be d e f i c i e n t i n organic materials f o r the greatest expression of i t s productive capacity." The E f f e c t of Physical S o i l Conditions Physical s o i l properties influence the accumu-l a t i o n of carbohydrate reserves i n d i r e c t l y , inasmuch as these conditions condition the development of the underground storage organs. Weaver (1919) reported that root penetration, root length, and the amount of root branching were reduced when plants were grown in compact s o i l s . Laird (1930) observed that a 3 inch layer of clay on sandy s o i l improved the root growth of two v a r i e t i e s of Bermuda grasses. Lamba et a l . (1949) 22 reported that aeration of s o i l caused an increase i n the root weights of Bromus inermis. The extent of s o i l aeration depends on the amount of s o i l pore space. Kmoch (1952) reported that the root weight of turfgrasses increased with increasing pore space. Both Lamba et a l . (1949) and Kmoch (1952) found that l i g h t , sandy s o i l s produced high root weights, and heavy s o i l s adversely affected root growth. The Influence of Water Water deficiency in plants causes poor* growth; consequently, the size of photosynthetic tissue i s reduced, which, in turn, r e s u l t s in a reduction of carbohydrates produced and stored. Troughton (1957) reviewed the work of Kauter (1933), Bailey (.1940), Langley and Fisher (1939), and Shively and -veaver ^1939) on the eff e c t of water on the growth of plants and accumulation of reserves. Kauter (1933), who grew various species of grasses at s o i l moisture contents ranging from 40 to 100 percent, i s quoted as recognizing that species d i f f e r i n t h e i r responses to water deficiency. At the end of the growing season two wetland grasses, Alopecurus  pratensis and Agrostis alba. had made the most root growth at 100 percent water capacity; Lol.ium i t a Ileum, Festuca pratensis, Fhle.um pratense, and Trisetum flavescens at S5 percent, Dactylis glomerata at 70 percent, and Arrhenatherum e l a t i u s at 55 percent. A l l species, except Dactylis glomerata, made the most herbage growth at 85 pefcent. Bailey (1%0) grev; 3 grass species at 19 to 30 percent s o i l water content. Plants grown at 30 percent produced more root and shoot weight than those grown at lower moisture contents. Variations i n s o i l moisture content were found to influence the shoot growth to a greater extent than the root growth. Langley and Fisher (1939) reported sim i l a r results with B u l b i l i s dactyloides. Shively and Weaver ( 1939) found thr.t the amount of underground material produced by several species of grass decreased with decreasing p r e c i p i t a t i o n . Madison (I962d) studied the e f f e c t s of i r r i g a t i o n frequency on Seaside and Highland bent grasses and reported that frequent i r r i g a t i o n , 5 times per week, increased plant population and the concentration of chlorophyll, but decreased verdure (quantity of green turf) and rooting. It would be interesting to know to "what extent i s the plant able to compensate f o r the reduction i n the quantity of photosynthetic tissue through the increase i n the amount of chlorophyll, The Influence of Temperature Troughton (1957) reviewed the l i t e r a t u r e on temperature effects on root growth and noted that d i f f e r e n t species have been shown to have d i f f e r e n t optimum temperatures for root growth. The optimum temperature at which Poa pratensis and Poa compressa produced the most root growth was found to be 24 lower by Brown (1939) than the optimum temperature where the highest herbage weight was gained,. Similar results were reported by Kauter (1933) with Lolium italicum, Festuca  pratensis, and Phieum pratense. and by Sprague (1944) with Bromus iner;;.is. Harrison (1934), and Barrow (1939), on the other hand, found that the optimum temperature f o r root and top growth was the same in the species studied by them. Harrison (1934) grew Kentucky bluegrass at various temperatures. At ?0 ° F, the bluegrass was supplied with nitrogen and defoliated p e r i o d i c a l l y . The growth at f i r s t was rapid and resulted in the exhaustion of reserve carbohydrates. Then growth became less and l e s s . Towards the end of the experiment the "plus nitrogen, and SO degree" temperature plants were .producing no more growth than the "no nitrogen" plants at the same temperature. The t i p s of rhizomes of the nitrogen f e r t i l i s e d plants died, but those which received no f e r t i l i z e r a f t e r return to normal temperature turned slowly upward and emerged above the s o i l . Harrison's work indicated that there are interactions between temperature and s o i l f e r t i l i t y factors. The high nitrogen content of the s o i l probably aggravates a condition within the plant i n which concentrations of certain nitrogenous compounds are approaching the l e v e l of t o x i c i t y . Harrison reported that i t was possible to k i l l plants at high temperatures by continuous f e r t i l i z a t i o n with "nitrogen". The accumulation 25 of nitrogenous compounds i n grass tissues at high temperatures were reported by Altergott (1937), S u l l i v a n and Sprague (1949), and others. Altergott suggested that the death of a. plant at high temperature was caused by the accumulation of ammonia. Sullivan and Sprague (1949) also ascribed the accumulation of nitrogenous compounds as one factor causing death. Another death-causing factor at high temperature, they pointed out, i s the excessive rate of r e s p i r a t i o n which leads to the exhaustion of reserve carbohydrates. Brown (1939) defined one effect of r e s p i r a t i o n as follows: "The decrease in growth rate with r i s i n g temperat\;re above the optimum, but below the maximum, i s conditioned by the i n -creased r e s p i r a t i o n or other factors. The increased r e s p i r a t i o n , because i t i s not accompanied by a s i m i l a r increase i n photosynthesis, reduces the net assimi-l a t i o n of carbonaceous food materials or other f a c t o r s . Bukey and Weaver (1939) studied the underground reserves of several p r a i r i e grasses and observed that summer drought reduced the reserves i n the roots of several Andropogon spp. C a r r o l l (1943) examined the e f f e c t s of drought, temper-ature and nitrogen on 15 turfgrass species and found that most injured by drought were Poa t r i v i a l i s and P. nemoralis; least . injured were Poa nratensis. Festuca rubra, F„ r. var. f a 1 l a x , Agrostis tenuj . 3, and A. cfinina. A r e l a t i o n s h i p between drought and nitrogen was observed by t h i s author, noting that the species from the high nitrogen section were less able to withstand s o i l drought than the same species from low nitrogen plots. Julander (1945), who studied drought resistance in range grasses, also 26 reported species differences in drought resistance. Kentucky bluegrass was the least r e s i s t a n t , followed by slender wheat-grass, smooth brome; blue stem was intermediate; buffalo grass was outstandingly r e s i s t a n t ; Bermuda grass, when watered, showed good resistance to heat. Julander did not find any major change in carbohydrates during drought, but noted that during drought, when growth i s stimulated by p a r t i a l d e f o l i a t i o n or by the addition of water, carbohydrates are l o s t . The Influence of Light The accumulation of reserves i s affected by both the duration of l i g h t and the i n t e n s i t y of l i g h t . The photoperiodic responses of grasses have received r e l a t i v e l y l i t t l e attention in l i t e r a t u r e . Troughton (1957) reviewed the work of Watkins (1940), Olmsted (1943), Benedict (1940), Sprague (1944), and Lovvorn (1945) on the e f f e c t s of photoperiod on herbage grasses. The highlights of his review are presented here. Watkins (1940) grew Bromus inermis at 5.5, 15, and l o hours daylengths. He found that the weights of roots were smallest at the short day treatment and equal at the other two treatments. The weights of the hay and the rhizomes increased with both increases i n daylength. Olmsted (1943) grew 6 species of the genus Bouteloua with 12, and 16 hours daylengths. After 5 months of t r e a t -ment there was a positive c o r r e l a t i o n between the dry weights of roots and treatment. Benedict (1940) found that af t e r 4 months, plants of Andropogon furcatus. Bouteloua g r a c i l i s . and Pan1cum virgatum produced greater dry weights of roots when grown at 20 hours daylength than those plants receiving only 8 hours of l i g h t . Andropogon S m i t h i i was unaffected by day-len g t h . Sprague (1944) exposed 6 species of grasses to 9 and 16 hours of daylengths f o r 6 weeks a f t e r emergence. Pla n t s grown at 16 hours had a smaller percentage of t h e i r weight i n the roots than had those with s h o r t e r daylength. Lovvorn (1945) reported, i n t e r a c t i o n s between daylength, temperature, and root development. The e f f e c t of reduced l i g h t i n t e n s i t y on p l a n t s has been studied by many workers. N i g h t i n g a l e (192?) observed t h a t the r a p i d groxvth of high carbohydrate, short day s a l v i a p l a n t s , when kept i n complete darkness, was associated with a decrease i n carbohydrates and an increase i n the n i t r a t e - f r e e s o l u b l e nitrogen f r a c t i o n . The response of the cotton plant to va r i o u s l i g h t i n t e n s i t i e s was studied by a. great number of workers, . among them, Ewing (1913), Mason (1922), Berkeley (1931), Knight (1935), Dunlop (1943), Tharp (1942), Eaton and R i g l e r (1945), and Eaton and Srgl e (1954). Although the work of these authors has l i t t l e d i r e c t bearing t o the study of l i g h t i n t e n s i t y responses i n grasses, they are valuable i n grass s t u d i e s inasmuch as the t r a n s f e r of the general p h y s i o l o g i c a l p r i n c i p l e s and techniques i s p o s s i b l e . One of the f i r s t s t u d i e s on the l i g h t i n t e n s i t y response of grasses was conducted by Graber e_t al_. (1927). They grew grass i n a dark room and measured the weight of new growth produced i n the dark. I t was found that the y i e l d obtained v a r i e d according to management treatments previous t o dark c o n d i t i o n s . I t was observed that p l a n t s l o s t carbohydrates C O i n the dark, the loss being 20 to 67 percent of the o r i g i n a l dry weight. The gain i n shoot weight was found to be 9 to 16 percent of the o r i g i n a l weight. I t was estimated that the unaccounted-for part of the reserves was lost i n r e s p i r a t i o n . Reid (1933) studied the e f f e c t s of shade on the growth of velvet bent and Metropolitan creeping bent grasses. The grasses were subjected to several degrees of shade at various times of the day. It was found that s l i g h t shade increased top growth, but heavier shade reduced i t . Shade affected root growth more than top growth, the reduction in root weight being more than in top weight. Similar observations were reported by Watkins (1940) with Bromus inermis. L'atkins reduced sunlight to about 7 percent cf i t s "ordinary" in t e n s i t y and found that the weights of roots and rhisom.es were greatly reduced, but the top growth was only s l i g h t l y affected by the shade. The chemical compo-s i t i o n a f t e r shade exposure was l i t t l e altered in-the. roots,, except for a decrease in sugar content; rhizomes, stubble, and top, however, showed a marked decrease in carbohydrates and an increase in nitrogen content. Watkins also found a r e l a t i o n s h i p between nitrogen f e r t i l i z e r and shade; i n combination the two factors increased the loss of carbohydrates i n the rhizome, stubble, and tops. Thomas and H i l l (1937) studied the influence of clouds on the rate of photosynthesis of a l f a l f a and wheat grown under f i e l d conditions. They found that the rate of photosynthesis of a l f a l f a i s a l i n e a r function of the sunlight i n t e n s i t y up to about 50 percent of the normal maximum i n Utah. Greater i n t e n s i t i e s were not found to increase the rate of photosynthesis appreciably. Only 16.5 percent of the net carbon dioxide assimilated could be accounted for top growth; the remainder, suggested Thomas and h i l l , was probably stored in the roots. This experiment was conducted towards the end of the growing 'season; therefore, these figures are applicable only to the end phase of the growth cycle. In the wheat, i t was found that 83.3 percent of the net assimilation goes into the top growth. This difference i n the accumulation of reserves between a l f a l f a and wheat i s no doubt related to the perennial and annual growth habits of these plants respectively. Benedict (1941) studied the growth of range grasses in reduced l i g h t i n t e n s i t i e s In Wyoming and found that shade, ranging between 28 and 70 percent of f u l l sunlight, decreased the root and top weights qf Affropyron cristatum, A. smith i i , and Bouteloua g r a c i l i s . .Distinct changes in. root/top ratios were not obtained. S u l l i v a n and Sprague (1943) grew perennial rye-grass in dark and found that the rates of loss of soluble carbohydrates in the dark were si m i l a r to the loss occurring i n the control plants grown in f u l l l i g h t , except that no re-storage occurred i n the dark. In the dark, fructosan disappeared e n t i r e l y a f t e r 22 days in the stubble, and a f t e r 16 days i n the roots. The soluble carbohydrates found aft e r 36 days i n the dark were: 0.22# sucrose and 0.41$! glucose i n the stubble, 0.15'p sucrose 30 and 0 .07^ f r u c t o s e i n the r o o t s . There was no i n d i c a t i o n that c e l l u l o s e , pentosan, or' l i g n i n , once elaborated, were r e u t i l i z e d as "food". In a l a t e r report S u l l i v a n and Sprague (1949) observed that p l a n t s at high temperatures behave i n some respects l i k e plants placed i n darkness. Both environ-mental c o n d i t i o n s lead to a rapid d i s s i p a t i o n of carbohydrate reserves and to the d i g e s t i o n of p r o t e i n . The n i t r o g e n metabolism, i n the two s i t u a t i o n s however, i s d i f f e r e n t . P l a n t s i n darkness accumulate a high concentration of n i t r a t e s which disappear l a t e r when the p l a n t s are dying. This i s an important observation because i t makes l e s s l i k e l y one hypothesis concerning the death of plan t s i n dark, v i z . t h a t death i s caused by the accumulation of t o x i c q u a n t i t i e s of nitrogen compounds. K i t c h e l l (1954) grew Lolium perenue under - 700 and 2000 foot-candle l i g h t i n t e n s i t i e s f o r 10 hours each day, and at two temperatures, 50°and 65°F. Highest root and shoot weights were gained at 2000 foot-candles with the temperature at 50°F. Least growth was produced at 700 foot-candles with the temperature at 65°F. In another experiment, M i t c h e l l ( 1 9 5 5 ) found that Lolium perenne, D a c t y l i s glomerata f and Pa spa 1 urn d i l a turn. when grown i n shade, had a lower p r o p o r t i o n of t h e i r weight i n the roots thsn p l a n t s grown i n the open. S i m i l a r r e s u l t s were observed by M i t c h e l l (1954) i n c l i p p i n g t r i a l s with Lolium perenne. In a l a t e r paper Bathurst and 'Mi t c h e l l ( I 9 5 6 ) a l s o reported that the reduction i n l i g h t i n t e n s i t y lowered the a v a i l a b l e carbohydrates i n pasture p l a n t s . Burton et a l . (1959) reported that the y i e l d of Cynodon dactylon, when grown under 64, 43, and 29 percent of normal l i g h t at midday, decreased with increase i n shade, the rate of decrease being much faster when "nitrogen" was applied at the rate of 1600 lbs/acre than when i t was applied at the rate of 200 lbs/acre. The shade-nitrogen interaction was found to be highly s i g n i f i c a n t . With no shade the high-nitrogen plots proiuced 5,US lbs. more dry matter per acre than low-nitrogen plots, whereas with the heaviest shade the high nitrogen plots yielded I 6 5 2 l b s . less than the heavily shaded low-nitrogon plots. The application of nitrogen thus proved to be harmful. The p o s s i b i l i t y of nitrogen t o x i c i t y was ruled out by the authors. Chemical analysis i n the above-ground organs did not show toxic amounts of nitrogen. Under heavy shade and 16C0 l b s . nitrogen per acre plants contained 25.7 percent snore crude protein and 29.6 percent less available carbohydrates than the control plants. It i s the authors' opinion that: "Apparently proteins were formed at the expense of carbohydrates, perhaps in this case as a mechanism to keep nitra t e and ammonia nitrogen from building up within the plant to toxic l e v e l s . It seems possible that the available carbohydrates l e f t a f t e r protein synthesis (6,4^) were inadequate to support the rate of growth as high as that measured at the low nitrogen l e v e l (9.1$ carbohydrates at 200 lbs/acre) The root and rhizome yie l d s decreased as shade increased, there being less than half as much y i e l d under the •5 0 s -heaviest shade as under f u l l l i g h t by the end cf the season 0 Below-ground reserves decreased as shade treatment increased, giving indexes of 2.2, 1 .6, and 0.1 for the respective shade treatments. The dry matter y i e l d per year on the high nitrogen plots decreased with Increasing shade, y i e l d i n g 63.2$ of control ( f u l l l i g h t ) under 64$ l i g h t i n t e n s i t y , 42.1$ of control under 43$ l i g h t , and 29.$$ of control under 29$ l i g h t . From these data a remarkably close c o r r e l a t i o n seems to exist between l i g h t i n t e n s i t y and dry matter production. At the low nitrogen l e v e l , shading resulted In increased moisture percentage in the grass, and also Increased percentages of l i g n i n (this was also reported by Sullivan and Sprague 1943 ), crude protein, true protein, phosphorus, calcium, ami magnesium. Cellulose percentage apparently was unchanged. Available carbohydrates in plants heavily shaded decreased to 57.6 percent of control. At the high nitrogen l e v e l shading had r e l a t i v e l y .less effect than at the low nitrogen l e v e l in the chemical composition of the grass. Available carbohydrates decreased to 76.2 percent of control as compared to a decrease to 56.7 percent of control at low nitrogen. The report of Burton et £l. (1959) confirms the findings of other authors reviewed here e a r l i e r regarding the interaction e f f e c t s of l i g h t and f e r t i l i t y l e v e l s . Y i e l d decline of shaded grass i s accentuated by heavy f e r t i l i z e r a p p l i c a t i o n . Burton and Jackson (1962) studied Coastal Bermuda grass, Fensacola bahia, common d a l l i s , prostrate d a H i s , and carpet grasses under three l i g h t i n t e n s i t i e s : 33, 66, and 100 percent of normal l i g h t . It was found that reduction i n l i g h t i n t e n s i t y also reduced the "sod reserve index"' of the grasses. The term "sod reserve index." was invented by these authors to express the dry matter production of grass in darkness. Its exact d e f i n i t i o n and explanation w i l l be given l a t e r in t h i s paper. Troughton (I960), working with young Lolium perenne plants, noticed that a decrease i n l i g h t i n t e n s i t y or s o i l water reduced the growth of the plant as a whole, but that reduction in. l i g h t decreased root growth more':• than shoot growth, while a decrease in the water supply had the opposite e f f e c t . Gordon et a l . (1962) grew orchardgrass under shade which was .50 percent of the normal l i g h t i n t e n s i t y . It was noticed that shading decreased the percentage of dry matter and increased nitr a t e content more than the application of nitrogen f e r t i l i z e r did. There was no change in the crude protein content. Shading also reduced the sugar content more than nitrogen alone. The authors assumed that the sugar content was reduced by an increased r e s p i r a t i o n rate r e s u l t i n g from an increased demand fo r nitr a t e reduction. Juska (I963) stu-sied the shade tolerance of bent-grasses, te s t i n g 11 bentgrasses under 70 percent l i g h t . S i g n i f i c a n t differences were noted between v a r i e t i e s i n t h e i r 34 response to shade. In general, v a r i e t i e s which performed best in sunlight performed best under shade. .3.ojae.. Hanagoicent Practices Xnfluencing the A c c u m u l a t i o n of Organic Reserves _in. Grass The foregoing review demonstrated the role of s o i l f e r t i l i t y and wotar i n the accumulation of carbohydrates; therefore, 1 itt. !»* More has to be added here. The influence of these management practices on reserves i s already made clear. Since the review of Troughton (1957) numerous papers have been published, on f e r t i l i z a t i o n research, but only a few of these may be mentioned here. Kennedy (195$) reported that f e r t i l i z i n g timothy with 25 l b s . of nitrogen per acre increased i t s production by 300 l b s . , and that the next 25 l b s . increment produced a 1300 l b s . increase. When orchardgrass was f e r t i l i z e d with 200 l b s . nitrogen per acre, i t increased root development over the no-nitrogen treatment. Oswalt et a_l. (1959) studied the root growth of brornegrass and orchardgrass under c l i p p i n g and f e r t i l i z e r treatments and reported that nitrogen f e r t i l i z a t i o n increased dry matter production and decreased root weight. It was suggested that since top yiel d s increased, even though there was a decline in. root development, the e f f i c i e n c y of root system was increased by the nitrogen •application. Burton et a l . (1959) applied 1600 l b s . and 200 l b s . nitrogen per acre on Bermudagrass and found that the high nitrogen reduced the t o t a l available carbohydrates. Baker (I960) investigated th? effect of auturrm uianage"nent and nitrogen f e r t i l i z e r on ?arly spring growth of «t general purpose ley and found that spring nitrogen s i g n i f i -cantly increased tho y i e l d s of early spring grass. The response to f e r t i l i z e r ranged from 9 to 28 poun.is of dry matter per pound of nitrogen applied. Autumn nitrogen was found to increase autvn.'in ana spring y i e l d s s i g n i f i c a n t l y , but autumn grazing and f e r t i l i s e r reduced the percentage of soluble carbohydrates i n the roots and stubble in November; nevertheless, the f a l l -f e r t i l i z e d swards s t i l l made the most growth next spring. Baker concluied that "any autumn treatment that encourages plant vigour and b u i l d up of reserves w i l l benefit spring growth." Baker himself r e a l i z e d , however, that autumn a p p l i -cation of nitrogen, even though i t encourages vigorous growth, could deplete the organic reserves, and quoted Sullivan and Sprague (1953) to t h i s e f f e c t . Baker's explanation of the problem i s that even though f a l l a p p l i c a t i o n of nitrogen reduced the reserves, i t increased growth, r e s u l t i n g i n larger t i l l e r s which,were possibly contributing to the larger spring y i e l d •loss (1962), "<f-plying several f e r t i l i z e r treatments to putting greens, reported that plots receiving 20 pounds nitrogen per 1000 square feet had the lowest root y i e l d s and 36 those receiving less nitrogen had higher root y i e l d s . One plot, however, where 20 pounds nitrogen, no phosphorous, and 8 pounds of potash were applied produced the highest root y i e l d among the high nitrogen plots, indicating that even though nitrogen tended to decrease root y i e l d s , high potassium could act as a buffer. It was also noted, that the lowest root y i e l d s were recorded on plots which received phosphorous and no potash. Goss (1963) indicated that a survey of putting greens located west of the Cascade Mountains in Washington State, consistently showed potash deficiency, most probably due to the leaching effect of high p r e c i p i t a t i o n . From the above observations and esp e c i a l l y those of Goss, i t may be seen that f e r t i l i z e r studies conducted i n various regions may have s p e c i f i c aspects s t r i c t l y related to the area where the tests are performed. Results and con-clusions from f e r t i l i z e r t r i a l s should be evaluated i n the terms of a p a r t i c u l a r ecological area. Madison (1962d) reported that nitrogen f e r t i l i z e r increased population density of Highland and Seaside bent-grasses. Y i e l d i n mg, dry weight per square dm. increased with increasing nitrogen but f e r t i l i t y differences were reduced when y i e l d per plant comparisons were made. It was noted that f e r t i l i z e r increased y i e l d s by increasing the population density rather than by increasing the size of the grass. High f e r t i l i t y l e v e l s also increased chlorophyll. Rooting, on the other hand, was reduced by high nitrogen rates. 37 Frequent i r r i g a t i o n increased the population of the Seaside and Highland s t r a i n s , but only increased Highland y i e l d ; i t decreased root development, dry weight, and chlorophyll. Thus the general effect of frequent i r r i g a t i o n proved to be dele-terious. In another paper Madison and Hagan (1962) reported that frequent i r r i g a t i o n reduced the root system, of bluegrass t u r f . M i t c h e l l (1962) studied the influence of nitrogen and I r r i g a t i o n on the root and top growth of forage crops, including orchardgrass. He found that nitrogen f e r t i l i z a t i o n decreased the root system as measured by methylene blue absor-ption; nevertheless, nitrogen also increased the root a c t i v i t y as i t was indicated by the increased absorption of methylene blue per gram of dry root t i s s u e . Dry matter production of the orchardgrass herbage was s i g n i f i c a n t l y increased by nitrogen a p p l i c a t i o n . There were, however, actions on the grass of combined f e r t i l i z e r and mowing, which caused the loss of plants. There was no evidence that the death of plants was attributable to disease organisms. I t was noted that loss was more pronounce! where cutting height was lower than 2 inches. Although there was no suggestion put forward by the author to explain the mechanism of t h i s e f f e c t , i t may be assumed that since both f e r t i l i z a t i o n and mowing are known to increase growth at the expense of reserve carbohydrates, the combined stimulating e f f e c t of these treatments caused the death of the grass by depleting the reserves beyond "the 33 point of no return". Irrigation and r a i n f a l l , too, possibly-contributed to growth stimulation and carbohydrate depletion, for Mitchel l observed that r a i n f a l l was relat ively high in 1958 and 1959 when mortality occurred. Supplemental i rr igat ion was reported to have reduced root growth as measured by methylene blue absorption and by root weights. Brink and Weibe (i960) found that overv/atering of golf course greens was common on the Lower Mainland of Br i t i sh Columbia. The adverse effect of excessive i rr igat ion should be thoroughly appreciated in lawn and sports-turf management on the Pacific Northwest and other l ike places where high prec ip i -tation is supplemented by generous i rr igat ion in the bel ief that plenty of water w i l l produce better tur f . One consequence of this practice is that reserves become dangerously depleted as a result of growth stimulation of tops and retardation in root development; compaction from play and implement operations more readily occurs on over irrigated so i l s , which in turn, also adversely affects the accumulation of reserves. Effects of Grazing and Mowing on the Accumulation of Reserves Grazing or mowing of turf removes part, usually a major part, of the photosynthetic tissue of a grass; On a pr ior i grounds i t is obvious that both the frequency and the height at which the grass is cut influence the accumulation of reserves; the more frequent and the more severe the clipping the more pronounced is the decline in food storage. If the reduction in the amount of carbohydrates produced equals the 39 amount needed for current growth, the grass survives indef inite ly , provided there is already enough storage food to meet emergency situations when external conditions are unfavorable for photo-synthesis. If , however, the defoliation removes most of the photosynthetic tissue and the remaining tissue is unable to f u l f i l l completely the plant's current need for food, the grass has to draw upon i t s reserves, and depletion of carbohydrates occurs in the storage organs. I f through frequent clipping the reserves are steadily depleted, the grass eventually w i l l die. In practice, the defoliation is seldom carried far enough to cause death. Sports turf and home lawns, although clipped frequently and closely, usually retain some reserves; a low level of reserves, i t may be presumed,is often insuf f i -cient to carry the grass through periods of climatic adversity or to help the grass to recover after injuries or from wear and s o i l compaction, pest and disease attack. The depletion of reserves through the removal of photosynthetic tissue is only one facet in reducing the carbo-hydrate reserves in the grass. Mowing and similar treatments stimulate new top growth at the expense of reserve carbohydrates; also, usually, mowing results in a cessation of root growth,* (Crider 1 9 5 5 ) . Defoliation, i t is commonly known, promotes vegetative growth of aer ia l parts and tends to prevent "reproductive 40 development". The turf as i t i s generally managed is not allowed to enter the growth phase when storage accumulation usually takes place v i z . in the late summer and the f a l l . Inasmuch as the accumulation of reserves is prevented and root development is reduced, the winter-hardiness of grass is lowered and poor spring growth often results , (Graber et a l . 1927.) While defoliation usually stimulates vegetative growth, i t may be assumed that under severe cutting treatments, growth is prevented or slowed before the actual exhaustion of reserves commences. This could happen when low cutting removes meristematic tissues. This is l ike ly to occur when, under reduced l ight intensit ies , internodes are elongated and meristeras are sparse, placed high and are removed by mowing. Sampson (1914) was one of the f i r s t to study the harmful effects of defoliation in grasses. He reported that the vegetative growth of Festuca v ir idula decreased as a result of harvesting three times annually for three years. Sarvis (1923) observed that clipping of Stipa comata and Stipa minor lowered the vigour of these grasses and increased their mortality. Sampson and Malmsten (1926) found that carbohydrates decreased as a result of defoliation in Stipa  lettermani f Agropyron violaceum f and Bromus polyanthus. Sampson and McCarty (1930) studied Stipa pulchra in Utah and found that harvesting at the time of flower stalk production and seed maturity tended to prolong vegetative growth and curbed the accumulation of carbohydrates„ 41 Graber et a l . (1927) reported that 22 mowings a year of Poa pratensis reduced the productivity of the grass; close cutting reduced subsequent productivity more than t a l l cutting. Graber (1929) l a t e r observed i n Wisconsin, where permanent bluegrass pastures had been grazed for more than 30 years, that insect injury from white grubs (Phyllophaga  spp.) and weed i n f e s t a t i o n appeared much more extensive i n pastures which had low organic reserves due to premature grazing and low s o i l f e r t i l i t y . On experimental plots where reserves were a r t i f i c i a l l y depleted by frequent and close mowings, weed encroachment was 10 times higher than on plots where only one cutting was applied and, therefore, where reserves were higher. In a l a t e r paper Graber (1931) once more reported s i m i l a r observations on weed encroachment and concluded: "The maximum competitive e f f i c i e n c y of bene-f i c i a l grasses , as measured by invasions of other plants among them, occurred generally when optimum f e r t i l i t y was combined with those practices of cutting or grazing which maintained a productive l e v e l of reserve foods i n such grasses. In this paper Graber also reported the re s u l t s of cutting and f e r t i l i z e r treatments on Poa pratensis p l o t s . On f e r t i l i z e d s o i l where nitrogen was applied at the rate of 110 lbs/acre, 6 clippings at a 1 inch height produced only 3&%> of the amount of dry matter obtained with one cutting on the control pl o t s . On u n f e r t i l i z e d s o i l , 6 cuttings at 1 inch height produced 43$ of the amount of dry matter obtained by one cutting. Graber's conclusion regarding these r e s u l t s are summed up as follows: 42 "Frequent and close removal of tops make a heavy draft on the supplies of available nitrogen so that i t may become a l imit ing factor. When regeneration is constantly stimulated by a f er t i l e s o i l or by abundant mineral, especially nitrogen f e r t i l i z a t i o n , the carbohydrate reserves are rapidly con-sumed and they become the l imit ing factor. Graber also recorded growth recovery on the treated plots and found that on plots cut 6 times, growth recovery was faster than on plots cut only once. On the f e r t i l i z e d plots the difference was more obvious. Graber attributed this to et iolat ion and to the inhibi t ion of bud development on the rhizomes because of the competition by the dense growth above. It was noted that subsequent regeneration on the plots cut once, occurred mostly from dormant buds. Cutting and f e r t i -l i z ing treatments (probably through influencing the speed of recovery and competitiveness of the bluegrass) were found to have effect on weed encroachment. On unfert i l ized s o i l weeds were 10 times more abundant on plots cut 6 times than on those cut only once in the previous year. On f er t i l i z ed plots, when cut 6 times in the previous year, weed encroachment was only 1/7 of the weed population found on the unferti l ized plot cut 6 times. Aldous (1930 a,b) studied the relat ion of organic food reserves to the growth of Andropogon scoparius. Sorgastrum nutajoa, Bouteloua curtinendula f and B. hirsuta and reported that the amount of food reserves decreased with the frequency of cutting and was inversely proportional to the height of cut. 43 He also found that increasing the interval between clippings early in the season resulted in a greater concentration of carbohydrates than increasing i t later in the season. Parker and Sampson (1931) grew Bromus hordeaceus and Stipa pulchra in water culture for 120 days. They observed that these grasses produced less dry matter when harvested at 15 day intervals than when harvested terminally. Smallest yields were recorded when herbage was removed at the time when the growth rate was at i t s maximum. McCarty (1935) studied Elymus ambiguus and Muhlen-bergla grac i l i s , applying two cutting treatments. The f i r s t group was clipped on June 24, and the other was harvested on August 27 at seed maturation. It was found that the amount of herbage growth, made subsequent to clipping treatment, and the concentration of accumulated carbohydrates, were roughly proportional to the number of days between the date of cl ipping and the end of the annual growth cycle. Similar results were reported by McCarty and Price (1942) as a result of their work with mountain forage crops in Utah. The concentration of reserves in the roots and stubble at the end of the growing season was related to the amount of herbage present throughout the growing period, and the time between the last defoliation and the end of the season. The concentration of reserves became less as the interval between the time of clipping and the end of the season decreased. Clipping of herbage at 1 inch height prevented the accumulation of reserves and also stimulated 44 regrowth at the expense of previously stored carbohydrates. With orchardgrass Sprague and Sullivan (1950 and 1953), reported that clipping resulted in the removal of an increasing proportion of the reserve substances as the clipping was made closer to the ground leve l . This was explained by the fact that the lower zones are richer in fructosan, the main reserve substance in grasses. It was observed that after each cutting the fructosan and sucrose concentration of the stubble and roots decreased. The authors suggested that the carbonaceous matter for the new leaf tissue, produced during the f i r s t few days after cutting, was obtained primarily from the reserves, hence the reason for the decline in reserves after cutting. This hypothesis was supported by the fact that new leaves were produced in almost equal amounts in both l ight and dark during the f i r s t few days of recovery. Crider (1955) observed that roots of orchardgrass stopped growing when tops were cut. The percentage of roots that stopped growth was proportional to the amount of herbage removed. This root growth stoppage occurred within 24 hours after defol iat ion. Root growth started again when top recovery was well advanced. The effect of f i r s t cl ipping on root growth was not so pronounced as subsequent defoliations. There was s t i l l some root elongation after the f i r s t cut, but the second clipping was followed by an unusually long pause in root growth. In species of grass, other than orchardgrass studied by Crider, 45 root growth stoppage following clipping was even more pronounced. Ward and Blaser (1961) removed the leaves of ind i -vidual orchardgrass plants and observed the response for 35 days following. It was found that the residual leaf area lef t after clipping greatly influenced the rate of regrowth. Drake et a l . (I963) studied the effects of nitrogen f e r t i l i z a t i o n and harvest management on orchardgrass and found that yields were increased by early i n i t i a l harvest, by a 3 inch cutting height and by 400 lbs. per acre of nitrogen. Interactions between these factors were highly s ignif icant . Cutting at the height of 1.5 inches prevented the expression of nitrogen response. At the time of f i r s t harvest, the stage of maturity showed more correlation with yield than with the cutting height, but the height of cut became more important in the subsequent harvests. I tal ian ryegrass studies were recently reported by Maeda (1961), and Ehara and Maeda ( I 9 6 I ) . Clipping decreased carbohydrates in roots and stubble, but the f i r s t cl ipping caused more loss of reserves in these organs than did subsequent cl ippings. During recovery, paral le l with advancing new top growth, a rapid reduction in the quantity of root and stubble reserves took place, the reduction being greater in the stubble than in the roots. One to two weeks elapsed before sufficient photosynthetic tissue was formed to produce carbohydrates in 46 excess of the amount required for current growth. Close correlations were found between root and stubble reserves and the rate of regrowth. Under cool conditions there were higher concentrations of root and stubble reserves at the time of clipping than under warm conditions. New shoot growth was more rapid immediately after the defoliation in the cooler temperature than in the warm temperature. The post-harvest decrease of reserves was faster at the higher temperature. Forage studies on perennial ryegrass are of much interest to turf specialists since Lolium perenne can be used on athletic f ie lds and on lawns as well as for forage. Sullivan and Sprague (1943) reported that after harvesting perennial ryegrass, the concentration of i t s root and stubble reserves rapidly decreased for 11 days, then remained the same or increased s l ight ly for another 11 days, then increased rapidly during the following 6 days. In a later paper, Sullivan and Sprague (1949) reported that the reduction of root reserves after the defoliation of perennial ryegrass was intensified by increasing temperature over a range of 50 to 90° F. The stubble showed a s imilar, but not so d is t inct , trend. Alberda (1955) studied the variations in the carbo-hydrate reserves of perennial ryegrass and found that carbo-hydrate concentration decreased following defol iat ion. He also noted that when defoliation coincides with the seasonal decline of carbohydrates in the spring, this decline is intensif ied. 47 Bluegrasses are used for pasture as well as for sportsturf and lawns, and much of the bluegrass l i terature is of interest to a wide technical public. Graber (1931), as previously mentioned, found that clipping Kentucky bluegrass at a height of 1 inch lowers i ts reserves. He concluded that: "An uncut remnant of one to one and a half inch of the f o l i a r parts of the grasses is decidedly more effective in maintaining a satisfactory level of reserves than a half inch of such growth.' In another paper Graber and Ream (1931) reported that frequent clipping of Poa pratensis at 1/2 inch height reduced i ts reserves. Ahlgren (1938) found that clipping Kentucky bluegrass at 1.5 inches height every time i t reached 4-5 inches increased the concentration of carbohydrates in the rhizomes during the period from June to November. Harrison ( 1 9 3 D , Darrow (1939), Spencer et aj.. (1949) reported that frequent clipping of Kentucky bluegrass below 3/4 inches was detrimental to the production of roots, rhizomes, herbage, and seed. Juska et_ a l . (1955) investigated the effects of cl ipping on the productivity of Merion Kentucky bluegrass and found that highest yields were obtained when i t was clipped at 2 inches height. Cutting heavily f er t i l i z ed plots at 3/4 inches inhibited root and rhizome development. 43 In another experiment, Juska and Hanson (1961) studied the growth of Merion and common Kentucky bluegrasses cl ipping at 1 inch and 2 inches, and at 1 and 5 mowings a week. It was found that clipping at the 2 inches height produced more root, rhizome and top growth than 1 inch cl ipping, and one weekly cl ipping produced more growth in these organs than 5 clippings a week. It was also observed that cutting height influenced the quantity of roots to a greater degree than cutting frequency. Sullivan (1962) observed that clipping Kentucky bluegrass at 1/2 inch gave lower yields than clipping at 2 inches height. Davis (1961) studied 18 varieties of Kentucky blue-grass and reported that a l l of the varieties contained less weed when mowed at 2 inches height than when mowed at 3 / 4 inches height. This increased competitiveness, of course, might not be due to the higher carbohydrate content under the high cut, but could also have resulted from the shading effect of the t a l l grass over the weeds, provided they were of prostrate nature. It must be pointed out, however, that according to many practical turf experts, "ta l l" mowing usually encourages invasion of certain weed species, and the name and morphological characteristics of weeds are important to know. I f we assume that the invading weeds were so prostrate in habit that even the 3 / 4 inches allowed them to retain most of their photosynthetic 49 tissue while the grass was deprived of them, and therefore starved, then the weeds' relative morphological advantage over the bluegrass is the answer to the problem. Since, however, most weeds are such that a 3/4 inches mowing height causes v i t a l damage by removing the leaves, the hypothesis just elabor-ated above is not l ike ly to be true; consequently, the explan-ation probably l ies in the f i r s t assumption, i . e . weed invasion at the 2 inches mowing height was restricted by the increased competitiveness of the grass, which is due to the higher concen-tration of carbohydrates and the shading effect of "tal l" grass. Madison (1962a) conducted tests to observe the in -vasion of Bermudagrass in lawns planted to temperate season turf species at Davis, Cal i fornia . It was found that blue-grasses showed a better resistance to invasion at 1/2 inch mowing height than at 1 and 3/4 inches height, even though close clipping produced a thin turf . Madison*s results thu3 seem to contradict the evidence presented by Davis. This may be easily solved i f we are satisf ied with the carbohydrate based explanation in the previous case, and accept Madison's own explanation in the lat ter case. Madison attributed the slower invasion of Bermuda-grass into the bluegrass turf at 1/2 inch mowing height to morphological factors. At this cutting height mowing removes the invading stolons of the Bermudagrass so that "Bermuda-grass establishes and consolidates i t s beachheads more slowly." 50 Youngner (1962) mowed 5 cool season lawn mixtures at 1/2"; some of the mixtures had Kentucky bluegrass in them as principal component. Wear resistance was the prime object of the test . It was found that resistance of a l l grasses to wear was reduced by 3 years of mowing at the 1/2 inch level as compared to mowing at 2 inches. Youngner suggested that restr ic ted root development under close mowing is the possible cause of reduced wear resistance. Other turf species, besides Poa pratensis. have also received a great deal of attention in l i terature . It is impossible to review a l l of them in this space save a few, reporting the most recent observations. Roberts and Bredakis ( i 9 6 0 ) studied the root develop-ment of bentgrass, bluegrass and fescue and reported, among other observations, that mowing height influenced the f e r t i l i z e r response of these species. Youngner (1962) in his wear-test experiments used several other cool season turf species besides the afore-mentioned Poa pratensis. These, too, showed greater resistance to wear when they were mown at 2 inches height for three years as .compared to mowing at 1/2 inch. Burton and Deal (1962) applied shade and clipping height treatments on southern turfgrass species, v i z . Bermuda-, zoysia-, Pensacola bahia-, and St. Augustine grasses. Each grass maintained a better sod when cut at a height of 2 and 1/4 51 inches than when mown at a height of 1 and 1/4 inches. Madison (1962a), as mentioned previously, studied the invasion of Bermudagrass into cool season lawns. Besides Kentucky bluegrass, which was referred to e a r l i e r , he tested several bentgrasses and Alta fescue. It was found that mowing at 1/2 inch height helped Seaside and Congressional bents to resist Bermuda-grass invasion better than mowing at 1 and 3/4 inches. Highland bent and Astoria bent were least able to resist invasion, and cutting height had no significant influence on invasion as reported with the bluegrasses. Alta fescue was favored over the Bermuda-grass by higher mowing. Subsequent papers by Madison (1962 b,c ,d , ) reported mowing height, mowing frequency and other management treatment experiments on several turf grasses. He found (1962b) that when Alta fescue was mowed at 1/2 inch, yie ld was reduced and the turf became thin and heavily invaded by weeds. When mown higher, y ie ld increased and the turf was free from weeds. Seaside and Highland bents gave higher means at the low cut of 1/4 inches and 1/2 inches respectively than at higher cuts, but i t was noted that the grasses responded differently to mowing height in the different seasons. "Seaside at the two highest cuts and Highland at the highest cut maintained yields from March to May-June, whereas yields of Alta at a l l mowing heights decreased in the heat of May-June. At the lowest mowing height, Seaside yields were also reduced in May-June and only Highland maintained y ie ld ." In another paper Madison (1962c) reported that longer intervals ' 52 between mowings increased y ie lds . Seaside bentgrass turf, when given a rest period of 1 to 5 days per week, increased yields as compared to mowing 5 times a week. The longer the rest from mowing, the higher the yield was found to be. Two or three consecutive days of rest were more effective than the same time spread through the week. In a study of the combined effects of mowing, i rr iga t ion , and nitrogen treatments on the population, y i e ld , rooting and cover of Seaside and Highland bentgrasses, Madison (1962d) found that shorter and more frequent mowing increased the yie ld of turf in contradiction to forage study reports by many other workers who observed that frequent mowing at shorter heights decreased y ie ld of forage grasses. When the "product" of turf , the verdure, was compared to the product of forage, the y i e ld , results were para l l e l . Madison introduced the term Verdure "to symbolize quantitatively the green grass on the ground that equates to the stubble of forage but i s the product of the turf grass culture." To summarize the foregoing reviews of l i terature on the study of the various factors influencing the accumulation of reserves Madison (1962d) may be conveniently quoted: "Carbohydrate accumulation is favored by such influences as cool temperatures, low available moisture, low nitrogen, high potassium, and high l ight levels. Conversely, reduction of carbohydrate content is favored by plent i ful water and nutrients, high nitrogen, high temperature, respiration, shade, and defol iat ion. Endogenous factors may also be involved. For example, mowing stimulates a burst of growth, and frequent low mowing w i l l produce a lowered ratio of mature to juvenile t issue. 53 The Measurement of Reserves Aldous (1930a) in his study of food reserves in pasture plants suggested that " . . . a determination of. . .storage . . .reserves throughout the growing season appears to provide one of the principal indexes to the growing requirements of plants." There have been numerous attempts to determine the grass reserves by chemical analysis. Heinze and Murneek (1940) compared several methods of sugar determination and found that Bertrand's (1906) method was the most accurate, but the Shaffer-Somogyi (1933) method was nearly as accurate and more convenient. Weinmann (1947), Sullivan (1951), Mays and Washko (1962), Smith (1962) are others who have offered methods for carbohydrate determination in grasses. Chemical determinations, however desirable they might seem, present several d i f f i cu l t i e s which make these methods impractical for the quantitative study of grass reserves. For one thing, the analysis requires the removal of a sample of roots and other underground organs together with the above ground parts. This disturbs the growth of the remaining sod, thus making i t useless for continued observations. During the removal of underground parts, even with the most careful exhu-mation and washing, many of the finer roots are lost . The root sample undergoing chemical analysis usually includes old root parts which are already dead at the time of exhumation and, therefore, no longer part of the grass. A quantitative analysis, 54 where v i t a l parts are not accounted for because of loss and because inactive parts are included, thus has l i t t l e use. Since direct chemical determinations with present day techniques seldom lead to satisfactory results , indirect approaches might be used instead. A method which would ensure continued observations by leaving the turf 's underground organs undisturbed would be most useful. Furthermore, a method based on the assumption that the weight of the above ground product, the herbage yield of the grass, reflects the quantity and concen-trat ion of the carbohydrate reserves, has promise. There have been several attempts to determine the reserves of grasses by weighing the dry matter produced in the absence of l i ght . Under conditions optimum for growth except the l ight , the grass continues to grow, using previously accumu-lated carbohydrates as energy and as a supply for building new structural material. The amount of new growth produced in darkness depends on the amount of carbohydrate reserves. The earliest report on the use of dark chambers in determining gras3 reserves is by Graber et a l . (1927) as mentioned ear l i er . It w i l l be remembered that these authors found that y ie ld varied according to management previous to dark conditions. Since the pre-dark treatments obviously affected the accumulation of reserves, the "aftermath" yield produced in the dark correlated well with the amount.of carbohydrates. 55 Sullivan and Sprague (1953) studied the relat ion of carbohydrate reserves to the aftermath yie ld of orchard-grass. A range of carbohydrate levels was established in the grass by varying the environmental conditions of temperature and l ight and by varying the frequency of c l ipping. After the determination of carbohydrate levels in samples, they were clipped uniformly and placed together for recovery. The yields produced after 25 and 40 days were compared. "The evidence obtained did not show that the production of after-math yield is dependent very largely on the level of carbo-hydrate storage." Juska and Hanson (1961) studied the growth of Merion and common Kentucky bluegrasses in dark to obtain a measure of root reserves. The method consisted of taking 40 cores, 2 inches in diameter and 3 inches deep, for each treatment. 20 of these were placed in a dark chamber, and the other 20 were used to obtain t i l l e r counts. The cores were packed in sand and watered as needed. Pre-dark treatments consisted of weekly or more frequent defoliations, and clipping at 1 and 2 inches. Data included the weight and number of t i l l e r s per gram of re-growth material and the number of t i l l e r s per gram of roots. It was found that weekly mowing produced more carbohydrates whether measured by the new dry matter produced or calculated on a t i l l e r number basis. It was noted that cores taken in October i 9 6 0 produced less regrowth than cores taken in October 1959, after a period of prolonged drought when leaf growth was 56 greatly inhibited. It was suggested by the authors that the rapid growth in I960 might have contributed to the reduction of reserves. They referred to Graber (1931) who also observed that the stimulation of top growth during periods favorable to growth reduced root reserves more rapidly than they could be synthesized by the leaves of the plant. It was the opinion of the authors that when grass is grown in dark, "the regrowth material may be considered as an indication of root, rhizome, and crown reserves since the regrowth is derived from stored materials." Burton and Jackson (1962) studied the accumulation of sod reserves in several southern grasses grown under three l ight intensit ies , 100, 66, and 33 percent of normal l ight at Tifton, Georgia. They obtained 6 inch sod plugs with a tool made from a piece of 6 inch pipe turned down on a lathe to a sharp cutting edge for easier penetration into the s o i l . A foot stand and a handle were welded to the cutter for easier operation. The plugs were removed from the s o i l by rocking the tool into the sod to the desired depth, and turning the handle to break the bottom of the plug. After removing the tool from the sod, the plugs were pushed out, weighed and trimmed to a uniform weight. Then these plugs were placed in No. 10 cans. The weights of s o i l and can were determined when held at 60 percent water holding capacity. Later, when watering, the containers were placed on a scale and brought up to this weight by adding the required amount of water. The plugs were placed 57 in a dark chamber under uniform ambient a i r temperatures and provided with a l l requirements for optimum growth except l ight . A l l new growth was harvested once a month, dried, and weighed. The data obtained were expressed as a "sod reserve index". This term was invented by the authors and defined as follows: "The sod reserve index is defined as the grams of new dry matter produced per unit area that is allowed to exhaust i t s e l f in the dark with adequate s o i l moisture. Since photosynthesis is prevented, the growth produced must be related to the quantities of carbohydrates and other energy-producing materials stored in any organs upon which the plant may draw for recovery. . . the main use for this method is to give a relative evaluation of sod reserve differences asso-ciated with variations in the environment or heredity of material tested. * Using this method, i t was found that the three l ight intensity treatments applied previous to sampling for dark room tests reduced the sod reserve index in proportion to the reduction in l ight intensity. Differences were significant in 4 out of 7 cases. Since only 2 plugs were taken from each plot, large sampling errors were detected, the value of the coefficient of var iab i l i ty ranging from 31 to 86 for sample pairs . In 1962, the same year as Burton and Jackson published their paper, there was another report on a similar method by Sprague et a l . (1962) entit led: "Regrowth of grasses in darkness indicates relative energy accumulation." This paper was read at the 1962 annual meeting of the American Society of Agronomy. Since only abstracts are available and since only a passing reference may be found to i t in the report of Drake et a l . (1963), i t is not possible to comment on i t . It should be 58 pointed out, however, that the method was not invented by Sprague as Drake et a l . assumed, but by Burton and Jackson as established by the pr ior i ty of their publication in 1962. Drake et a l . (1963) obtained sod plugs, 3 inches in diameter and 4 inches deep, each containing 1 orchardgrass plant. These plugs were placed in a dark room for 10 days. At the end of this period new leaf growth was measured. The data collected indicated that the greatest carbohydrate reserves were produced by treatments of 3 inch height of cut and high nitrogen applications. Although there were highly significant differences between treatment effects, there were no inter-actions detected in the data recorded by the dark room exhaustion method, but there were interactions observed when yield data from plots grown in light were analyzed. The authors concluded from their observations that: "It appears that carbohydrate reserve as i n -fluenced by such management factors as stage of maturity at i n i t i a l harvest, height of cutting and associated so i l temperatures, and rate of f e r t i l i z e r nitrogen applied may be the key factor to the rapid recovery by and high yields of Orchardgrass. The l i terature which has been reviewed up to this point tends to support the hypothesis that yie ld or vigour of grass depends mainly on i t s reserve content, which, in turn, is dependent on ecological factors and management practices. Madison ( I960) suggested that there are some d i f f i -culties in using yield data for turfgrass evaluation. Again, Madison and Hagan (1962) pointed out that: 59 "In contrast to pasture studies, yields of turfgrass do not direct ly express the effects of treatments. The amount of plant surviving beneath the cutter bar may be more pertinent information.. . "In a forage 3tudy, with comparatively longer periods between mowings, the stubble left is a small percentage of the yield and may repre-sent an unusable fract ion. With turfgrasses, that are mowed frequently, the "usuable crop" is the portion that passes beneath the cutter bar and is lef t behind. Practices that favor the portion remaining are not necessarily those that can be evaluated by weighing that is re-moved. Madison (1962d) felt that there existed a need for a term describing the part of the grass which remains beneath the cutter bar of the lawn mower: "For lack of a suitable term, I have chosen to use verdure in this paper when referring to the l iv ing grass above the ground not removed by mowing. Both quantitative and qualitative concepts are carried by verdure. and as vert (English law) i t carries - the concept of the tota l amount of green growth. Verdure was determined by hand shearing an area after regular mowing to remove the effective photosynthesizing leaf surface. A stubble was l e f t , so not a l l the organic matter was removed from the s o i l surface. Rapid regrowth indicated that many growing points remained after this shearing. In shearing to a uniform depth to remove green leaves, brown dead leaves were included in the material removed. Thus, though verdure is not exactly defined, no d i f f i cu l ty was experienced in getting reproducible results , since hand shears tended to "bottom" on the thatched stolons as the last green leafiness was removed. Madison in this paper used both yield and verdure measurements to compare treatment effects. Both the verdure 60 and the yie ld of Highland bentgrass were highest under high f e r t i l i t y conditions, but mowing and i rr iga t ion , while i n -creasing y ie ld , decreased verdure. This, in Madison's opinion, also indicates that "yield is often inappropriate for evalu-ating treatments on turfgrass." It was found that yields and verdure were both high because the f e r t i l i z e r treatment increased the number while plants remained about the same size; irr igat ion and cutting, on the other hand, resulted in more and smaller plants which gave high y ie ld but reduced verdure. Madison pointed out that a short dense turf having a high population is desirable on putting greens, and that this turf condition can be achieved by providing high f e r t i l i t y , increased i r r i -gation and mowing frequency and low cutting height. Since these treatments, except the f e r t i l i z e r , were shown to produce low verdure values, a good putting green cannot have a high verdure. Of course, Madison did not say that high verdure means high turf quality. Perhaps high and low verdure values can be equally acceptable for a good quality turf depending upon the purpose for which the turf is intended. Both yield and verdure are useful measures of turf-grass quality, and both methods of measurement could be used singularly and in combination. As far as the measurement of reserves is concerned, the carbohydrate reserve index method, described by Burton and Jackson (1962), appears to be one of the best means for the determination of grass reserves, and, indirect ly , one of the most useful indexes of turf quality. 61 I I I . INVESTIGATIONS  A. MATERIALS AND METHODS Although several workers have used the yie l d s of et i o l a t e d foliage as an index of the reserves i n clipped t u r f , f o r the most part, they have used the approach casually. The need for a more methodical study of the technique i s amply shown in a review of relevant l i t e r a t u r e . The report which follows i s an attempt to examine the approach and to determine i t s useful-ness as another technique by which the functions of the under-ground and surface organs of turfgrasses may be studied. 1. The Turf Coring Instrument The instruments usually used to obtain t u r f cores for experimental purposes are patterned a f t e r the greens' hole cutter. Although t h i s tool i s very handy for sampling when a quick assessment of t u r f condition i s required, i t may not y i e l d cores suitable for the study of reserves on l i v e t u r f samples. The turning-twisting action during the lowering of the t o o l into the sod breaks many of the roots within the core, thus depriving the grass plant of some of i t s underground re-serve supply. Another d i f f i c u l t y associated with t h i s sampling process i s the removal of the t u r f core from the t o o l . As the core i s -ejected from the t o o l with the aid of a foot pedal, i t i s subjected to considerable compaction. A further problem with cores obtained i n t h i s manner i s that they have to be 62 t r a n s f e r r e d t o a s u i t a b l e c o n t a i n e r t o p r e v e n t t h e i r d i s -i n t e g r a t i o n a n d d r y i n g o u t . I f t h e c o r e s a r e t a k e n i n c o a r s e t e x t u r e d s o i l s t h e y may f a l l a p a r t d u r i n g t h e t r a n s f e r , e s p e c i a l l y w h e n t h e t u r f i s y o u n g a n d h a s a s p a r s e r o o t s y s t e m . To o v e r c o m e t h e s e d i f f i c u l t i e s , a t u r f c o r i n g i n s t r u -ment ( F i g s . 1, 2, a n d 5), b a s e d o n a s o i l c o r i n g t o o l u s e d b y s o i l s c i e n t i s t s , was c o n s t r u c t e d t o o b t a i n u n d i s t u r b e d s o i l s a m p l e s . T h i s t o o l i s made o f a h e a v y s t e e l p i p e w i t h a s h a r p c u t t i n g edge a t one e n d . A f i t t i n g m e t a l l i d , w h i c h s e r v e s a s a p o u n d i n g p l a t f o r m , c o v e r s t h e t o p p a r t o f t h e p i p e . A r o u n d m e t a l r o d i s w e l d e d t o t h e c e n t r e o f t h e l i d . On t h i s r o d a s l i d i n g w e i g h t c a n be moved up a n d d o w n . The l i f t i n g a n d d r o p p i n g o f t h e w e i g h t d r i v e s t h e t o o l i n t o t h e s o i l , a n d t h e c o r e s a r e , t h e r e f o r e , n o t e x p o s e d t o t w i s t i n g . When t h e d e s i r e d d e p t h i s r e a c h e d , t h e t o o l i s t u r n e d a r o u n d w i t h t h e h a n d l e s t o b r e a k o f f t h e b o t t o m o f t h e c o r e , t h e n t h e s a m p l e r i s l i f t e d o u t o f t h e s o d . S i n c e t h i s t w i s t i n g r e s u l t s i n a s h e a r i n g s t r e s s w h i c h c o u l d b r e a k r o o t s e v e n a b o v e t h e p l a n e o f s h e a r i n g , a c a l c u l a t e d d i s t a n c e i s l e f t b e t w e e n t h e c u t t i n g e d g e a n d t h e i n t e n d e d b o t t o m o f t h e c o r e . The e x c e s s s o i l a n d damaged r o o t s a r e c u t o f f f r o m t h e b o t t o m o f t h e c o r e a f t e r i t i s t a k e n o u t o f t h e s a m p l i n g t o o l . The s o i l s a m p l e r a c c o m m o d a t e s a s t e e l t u b i n g c y l i n d e r w h i c h f i t s i n t o t h e c o r i n g t o o l . When s a m p l i n g i s c o m p l e t e d , b o t h t h e t u r f c o r e a n d t h e c y l i n d e r a r e r e m o v e d a s a u n i t f r o m t h e t u r f s a m p l e r , t h e c y l i n d e r r e m a i n i n g p e r m a n e n t l y a r o u n d t h e 63 Fir,. 1. The Coring Instrument 6 4 F i g . 2. Parts of the Coring Instrument Front row: Back row: handle rod locking bar s l i d i n g weight pounding platform with guiding rod for s l i d i n g weight the main part of the t o o l core holder cylinder 65 F i g . 3. Steel cylinder Cedar blocks to support short cores Clipping shears with welded walls 66 F i g . 4 CORING INSTRUMENT ALL DIMENSIONS IN . INCHES SECTION A-A MAIN PART OF TOOL 4i O.D. : CYLINDER £ THICK WALL CORE HOLDER CYLINDER S C A L E ' I. F U L L S I Z E L O C K I N G B A R 67 • F i g . 5 ' CORING INSTRUMENT - I N CO (SO' W E L D SECT ION B-B POUNDING PLATFORM WITH GUIDE ROD 3 D. § i ' t i \ •t. SECTION C-C SLIDING . WEIGHT 14 8 , HANDLE ROD 6 8 core as a plant pot. The use of a cylinder in this manner not only obviates the risky transfer of the turf core into a container but i t also eliminates the necessity of pushing the core out of the sampler with force. When the sampler is turned upside down, the cylinder with the core in i t simply sl ips out. Since the cylinder functions as a pot, the core surface l ies approximately below the brim of the cylinder to provide for the retention of water. Another advantage of having a brim is that i t serves as a guide when harvesting with the clipping shears. As the watering of the samples in the growth chamber creates humid conditions, the cylinders are given a cadmium coating to prevent rusting. The use of cardboard, p last ic , and t in tubings in place of coated steel cylinders would lower the cost; however, they do not retain shape, or may be fractured while being forced into the s o i l . Putting greens excepted, most sods contain sharp stones which, at times, r ip or deform non-steel tubings; small stones sometimes get caught between the inner tool wall and the cylinder, and they may damage a card-board or plastic tube. The steel cylinders, because they retain their shape, can be used again after proper washing and s t e r i l i z i n g . Near the top of the instrument, just above the cylinder, two openings are provided on opposite sides of the tool into which a bar can be inserted to lock the cylinder into position while driving the corer into the sod. Another pair of openings accommodate another bar, a round rod reaching across the tool and well beyond i ts walls to provide handles for pulling the tool out of the sod. These handles are also 69 useful when the t o o l i s being driven down as they provide a means of adding weight by stepping on them. The t u r f corer t o o l requires cleaning a f t e r use and sharpening of the cutting edge with a "ball-pane" hammer and a round f i l e a f t e r 50-75 samplings, depending on s o i l conditions, and sharpening on the lathe af t e r about 300 samplings. I f frequent use of t h i s t o o l i s anticipated i t may be necessary to provide for a replaceable cutting end, made of high quality s t e e l . Repeated sharpenings may bring the cutting edge too close to the bottom of the core, thus decreasing the o r i g i n a l l y calculated minimum distance necessary for safety from shearing stress. 2. Sampling; i n the F i e l d P r i o r to each sampling lawns and experimental plots of established turves were given uniform mowing at the height of 3/4 of an inch for a l l turfgrass species on a l l sampling dates regardless of the season. On putting greens lower mowing heights were applied consistent with the mowing heights on regular greens. Although the optimum mowing height varies with the species and with the season, the adherence to a uni-form pre-sampling mowing height was necessary to give a uniform start for the subsequent growth i n the dark chamber. Locations for sampling were randomly selected, except that obviously diseased spots, weeds, and uneven surfaces were avoided. Pre-sampling treatments and management history were recorded where such data were ava i l a b l e . 70 3. Treatments Following Sampling Once the cores were sampled, they were trimmed to size by removing any excess s o i l from the bottom that extruded from the sleeve. Also, at the top of the sleeve the core surface was adjusted, when necessary, so that i t was set l e v e l and 1/2 inch below the brim of the cylinder. In several experi-ments where the object was the study of l o c a l i z a t i o n of reserves, various core lengths were used; therefore, to accommodate cores which were shorter than the cylinders, round wooden blocks ( F i g . 3) of various heights were made to f i t into the cylinders as supports. The cores with containing cylinders were put on enamel trays and were moved into a dark room where they were kept under standard temperature and moisture conditions. To avoid disease attack i t was necessary to reduce surface moisture a f t e r watering. This was accomplished by putting out the trays with the samples i n open a i r a f t e r n i g h t f a l l following each watering, and moving them back into the chamber next morning. This practice allowed some photosynthetic a c t i v i t y during the early morning hours. Since, however, watering was required only at 2-4 days i n t e r v a l s , the early morning photosynthesis did not exceed 8 or 10 hours per week. I t i s not l i k e l y that i t could appreciably a l t e r the r e l a t i v e carbohydrate concen-t r a t i o n i n the samples. However, i t may have prolonged somewhat the period during which the exhaustion of reserves took place. 71 U. Harvesting of Et i o l a t e d Grass Grass elongation i n dark.is faster than i n l i g h t because, i n addition to the meristematic growth that occurs under both conditions, darkness also results i n increased c e l l elongation. I f reserves are s u f f i c i e n t l y high, the new growth i n the dark may amount to f i v e to six inches i n the f i r s t ten days. Since the preliminary tests showed that the exhaustion of reserves may take 3 0 to 4 0 days a f t e r the beginning of the dark treatment, i t was found necessary to remove the new growth several times during the experiments to prevent the lodging of long grass shoots. The longer grass shoots are allowed to grow the larger w i l l be the r e l a t i v e t r a n s p i r a t i o n a l loss of water and the r e l a t i v e r e s p i r a t i o n a l loss of carbohydrate reserves; standardization of c l i p p i n g i n t e r v a l s i s therefore necessary. Frequent c l i p p i n g , on the other hand, increases experimental error due to uncontrollable variations i n c l i p p i n g height and other errors associated with the handling of samples. Frequent c l i p p i n g also r e s u l t s i n greater damage to grass tiss u e s , increased r e s p i r a t i o n and hence greater losses of carbohydrate reserves. Clipping frequency of ten day i n t e r v a l s was accepted as standard, except i n experiments 1 and 2 which were explora-tory t r i a l s , and i n experiment 9 which was also a preliminary test. For the purpose of harvesting, a pair of c l i p p i n g shears ( F i g . 3) was equipped with metal sides along the edges of the blades to r e t a i n the harvested grass. 72 5. Drying of Grass Clippings Since the oven dry weight i s the basis on which the res u l t s are expressed, i t i s of paramount importance that the drying procedure be standard. There was no appreciable d i f f e r -ence when the r e s u l t s of 12 and 16 hours drying time at 80° were compared (when both drying periods were tested at 80°). There were, however, 2 to 3 percent differences when 80 and 100 degrees overnight drying temperatures were employed. The data reported i n t h i s paper were obtained with the following drying procedure. The clippings were coll e c t e d i n small aluminum f o i l pans and were dried i n an e l e c t r i c oven at atmospheric pressure at 80° for 16 hours, as suggested by Greenhill (I960). Accord-ing to t h i s author, a more accurate technique for drying herbage samples would be to dry them over P2O5 at 40°. Inasmuch as the samples were many and the f a c i l i t i e s for P2O5 drying limited, the s l i g h t l y less s a t i s f a c t o r y f i r s t procedure was adopted as standard. B. OBSERVATIONS AND RESULTS (1) A preliminary experiment was conducted i n May-June, 1962. Two cores were obtained from each of four selected lawns i n the Vancouver-Point Grey area on May 15, 1962. Descriptive comments on the four locations follow: Location "A", a well kept bluegrass-fescue lawn; 73 looked a f t e r by two resident gardeners on a private estate; weekly mowing; bimonthly f e r t i l i z e r applications; sprinkling every other day; upland location; heavy shade from large trees; parts of the lawn receive some sunshine for several hours in mid-afternoon. Location "B". a poorly kept lawn of fescue and bent grasses; lawn mowed once or twice a month; f e r t i l i z e d once a year; watered once a week or les s ; fungicides or chemical weed-k i l l e r not used; upland location; northern exposure; receives direct sunlight for 2 to 3 hours i n the morning. Location "C", a well groomed lawn on the U.B.C. campus with professional maintenance practices; composed mostly of perennial bluegrass with some fescue; upland,location, s l i g h t l y sloping northward but receiving d i r e c t sunshine a l l day; s o i l i s somewhat compacted from student t r a f f i c . Location "Dn, another U.B.C. campus location with lawn composition and maintenance practices as at location "C"; not a prestige location, and i t may occasionally s u f f e r from neglect during peak working periods; d i r e c t sunshine i s about 4 hours less than at location "C"; compaction i s about the same as at "C". In t h i s preliminary experiment the main concern was the handling of the t u r f coring instrument. I t was found to be rather heavy; as a factor i n sampling convenience t h i s f a c t i s not to be overlooked. Although one man can carry the t o o l , i t i s very h e l p f u l i f another can carry the cylinders, replace 74 cores or f i l l the holes with s o i l and pack samples. The eight cores were placed i n the dark room; the harvesting of e t i o l a t e d grass took place a f t e r 20 days growth, on June 4, 1962. The obtained sod reserve indexes, the averages for two cores for each location, are given i n Table I I . : Table I I . Sod reserve index means (exp. 1) Location Sod reserve index "A" 52.0 "B" 81.5 " C " 145.0 " D " 214.5 The basic data and calculations are given i n Appendix A. S t a t i s t i c a l calculations follow the procedures of Steel and Torrie (I960) The re s u l t s were encouraging i n that they indicated that the method offered a suitable range of v a r i a t i o n , and differences i n management and environment appeared to be refl e c t e d i n the sod reserve indexes. (2) Another t r i a l was designed to further the develop-ment of a standard sampling technique. During the sampling tests an unforeseen problem was encountered i n lowering the t u r f corer instrument into the sod. As the s o i l of the sampling area was g l a c i a l t i l l and outwash, stones were abundant i n the s o i l . When the lawns were established, the larger stones were 75 usually removed, but many of the smaller stones remained. These stones made the core sampling rather troublesome, and a good core could be obtained only a f t e r 4 or 5 attempts. The cutting edge of the tool required frequent sharpening on these locations. Eight cores were obtained from an area of 2 x 2 feet on a recently established (2 year old) lawn on the U.B.C. campus. The lawn i s composed of perennial and annual blue-grasses and fescues. The area i s rather poorly drained. Direct sunshine i s received during the early morning and late afternoon hours. Maintenance practices were s i m i l a r to those of locations "C" and "D" i n experiment No. 1. Cores were obtained on June 7, and harvesting took place on July 6, 1962. The average sod reserve index of the 8 cores a f t e r 30 days growth i n dark was 208 milligrams. The standard devi-ation was +_ 22.45, and the c o e f f i c i e n t of v a r i a t i o n was 10.8%. (The basic data and calculations are given i n Appendix B). The c o e f f i c i e n t of v a r i a b i l i t y i s lower than any given by Burton and Jackson (1962) i n t h e i r study. Again, the r e s u l t s encouraged further t e s t i n g . (3) This experiment was designed to study the l o c a l i -zation of reserves i n the t u r f core and to f i n d out more about the adequacy of a four inch standard core depth. Cores were obtained from the same location as i n the previous experiment, and were trimmed to four d i f f e r e n t sizes, v i z . 1, 2, 3 , and 4 76 inches of s o i l core. There were eight cores at each depth. No wooden cores were used i n t h i s experiment to support the tu r f cores shorter than 4 inches; but vermiculite was added to f i l l the cylinders containing the short cores. Cores were taken from the lawn on June 28, and were grown i n the dark f o r 20 days; two harvests were taken at 10 days i n t e r v a l , July 6 and July 16, 1962. The arithmetic means of the sod reserve indexes of the 4 treatments are given i n Table I I I . : Table I II . Treatment means (Exp. 3) Treatments Sod reserve index 1 inch core depth 329 .7 2 " " " 349.2 3 " " " 405.5 4 " " " 350.5 Analysis of variance did not show a s i g n i -f i c a n t difference. (Appendix C). Although a negative result such as t h i s i s a weak base, i t provides some support for the b e l i e f that the reserves i n a t u r f , managed as t h i s was, are l o c a l i z e d i n the upper few inches of the v e r t i c a l p r o f i l e and that a core four inches deep i s adequate f o r sportsturf reserve index determinations. (4) Inasmuch as the b e l i e f i s general that carbohydrate reserves are well d i s t r i b u t e d i n the root-crown system of 77 g r a s s e s , and inasmuch as t h e p r e v i o u s experiment i n d i c a t e d l o c a l i z a t i o n of. most o f t h e r e s e r v e s i n the upper i n c h or f r a c t i o n o f an i n c h o f t h e s o i l p r o f i l e , a c o n f i r m a t o r y s t u d y was made. Cores were t a k e n from a U.B.C. campus lawn, t h i s time from a d i f f e r e n t l o c a t i o n t h a n t h o s e o f t h e p r e v i o u s e x p e r i m e n t . I t was e s t a b l i s h e d l a r g e l y t o Kentucky b l u e g r a s s o f unknown age. The l o c a t i o n was not shaded. Three c o r e l e n g t h s , (of 1, 2, and 3 inches),not f o u r as p r e v i o u s l y , were used i n t h i s e x p e r i m e n t . S i n c e t h e r e was much v a r i a t i o n from c o r e t o core i n t h e p r e v i o u s e x p e r i m e n t , g r e a t e r c a r e was e x e r c i s e d i n s a m p l i n g c o r e s f o r t h i s e x p e r i m e n t . I n s t e a d o f random s e l e c t i o n o f samples, u n i f o r m i t y was t h e g u i d i n g p r i n c i p l e i n o b t a i n i n g c o r e s . The number o f r e p l i -c a t i o n s was 8. As t h e r e was r e a s o n t o s u s p e c t t h a t i n t h e p r e v i o u s experiment t h e 20 days growth p e r i o d d i d not exhaust c o m p l e t e l y t h e r e s e r v e s , the c o r e s were kept i n dark f o r 3 0 days. Dark t r e a t m e n t s t a r t e d on August 18; c o r e s were c l i p p e d t h r e e t i m e s a t 10 days i n t e r v a l s , v i z . on August 28, September 7, and September 17, 1962. The a r i t h m e t i c means of the t h r e e t r e a t m e n t s , r e p r e -s e n t i n g 8 r e p l i c a t e s and based on the t o t a l s o f the t h r e e h a r v e s t d a t e s are g i v e n i n T a b l e IV.: • Table IV. Treatment means (Exp. 4)  Treatments Sod reserve index 1 inch core depth 149.7 2 " " " 165.0 3 " " » 180.0 The analysis of variance, again, did not show s i g n i f i c a n t differences {Appendix D). ( 5 ) The object of t h i s preliminary experiment was to investigate the ef f e c t of f e r t i l i t y differences on the accumu-l a t i o n of reserves. On a home lawn, the same as described i n the f i r s t experiment as location "A", ten f e r t i l i z e r treatments were applied during the l a s t week of June, 1962. The various f e r t i l i z e r mixes were applied i n conjunction with topdressing treatments. Treatment No. 10 received neither f e r t i l i z e r nor topdressing. The lawn area had varying shade conditions, treatments Nos. 1 to 5 receiving the least amount of l i g h t . The available land was limi t e d , and therefore, plots were not well arranged or suitably r e p l i c a t e d . Although f e r t i l i t y differences were observed among plots following f e r t i l i z e r treatments.for about 6 to 8 weeks, at 10 weeks to the eye they had disappeared. No differences i n green weight, of any importance, were noted on the 10th week. It was hoped, nonetheless, that differences might s t i l l be detected i n the carbohydrate reserves. To ascertain t h i s , 79 three cores were taken from each of the ten plots on September 9, 1962, and were placed in the dark room. Harvesting took place 10 and 20 days l a t e r , on September 19, and September 29, 1962. Analysis of variance did not reveal s t a t i s t i c a l l y s i g n i f i c a n t differences i n sod reserve indexes. (Appendix E). Although i t i s doubtful i f perceptible differences between plots i n the f e r t i l i z e r t r i a l s persisted much beyond eight weeks, and although i t i s even less l i k e l y that sod reserves were much altered by the f e r t i l i z e r s used, d i f f e r -ences attributable to differences i n hours of sunshine may have been perceptible. Plots 1 to 5 received much less incident r a d i a t i o n than did plots 6 to 10. The mean sod reserve index for plots 1 to 5 was 47 .6 mgs. and the mean sod reserve index fo r the sunnier plots, 6 to 10, was much higher at 67.3 mgs. The difference i s s t a t i s t i c a l l y s i g n i f i c a n t . (Appendix E, second analysis of variance). (6) Four golf courses were selected i n Vancouver, repre-senting a variety of s o i l conditions and management practices, with a view to following the sod reserve index through the winter season. Three greens were chosen on each course and one fairway on one of the courses. Three cores were taken from each of the selected greens and from the fairway on every sampling date. Although the selection of a coring location on a green was large l y without r e s t r i c t i o n , coring near holes was avoided to in t e r f e r e with play as l i t t l e as possible. This, 80 of course, means that the samples were obtained from the less compacted and worn parts of the greens. Care was also taken to avoid the incl u s i o n of holes i n the core when sampling was preceded by a e r i f i c a t i o n ; thus the cores were extracted from the small area l e f t out by the a e r i f y e r . This was necessary to provide uniformity i n green-to-green comparisons. Spots with annual bluegrass intrusions were also avoided i n sampling, so that a l l greens at the four clubs provided samples with perennial t u r f . The fairway sample contained Kentucky bluegrass and some annual bluegrass. The f i r s t sampling i n the f a l l of 1962 apart, a l l cores were taken on the same day on the four golf courses. The golf courses are under the management of super-intendents who have been trained i n the old school of turfgrass management; each has "graduated" from the lawn mower; t h e i r work i s highly regarded. Their management records are.not detailed, or are not kept at a l l ; information on management practices and greens history was obtained from them o r a l l y . A b r i e f description of the courses and t h e i r management i s given below. (a) McCleery Golf Course, a public course, operated by the Vancouver Parks Board; located on a lowland area (Ladner s o i l s e r i e s ) , near the Fraser River. The course i s 4 years old, but i s well known and well used. There are approximately 80,000 rounds played on i t every year, and i t i s xopen f o r play a l l year round. As a consequence, compaction of greens i n winter from heavy play is quite common. Drainage i s adequate. A new super-81 intendent was appointed recently, and unfortunately, he did not i n h e r i t the well kept records of the previous superin-tendent. As a consequence, very l i t t l e i s known of manage-ment practices on th i s course. There are 6 permanent and 5 temporary labourers on the maintenance s t a f f . Although records of f e r t i l i z e r used i n the e a r l i e r years of the golf course are not available, i t i s known that 10:20:10 f e r t i l i z e r was applied frequently. Presently applied rates are 60 to 100 pounds of 6:8:10 f e r t i l i z e r per green, applied intermittently to replace nutrients used by growth and l o s t through leaching. L i t t l e or no topdressing was used u n t i l now, according to the present superintendent. Water i s applied by overhead i r r i -gation 3 nights' a week for 4 to 6 hours each time in the summer season. Mowing of greens varies from 1 to 4 times each week, and mowing height between 1/4 and 5/16 of an inch depending on the season. For the control of certain diseases PMAS i s sprayed on greens about once a month. The only record of a disease problem i s dated on A p r i l 16, 1963: "Red thread and Copper spot on almost a l l greens a f t e r a long s p e l l of wet weather." The only other problem referred to i s the already mentioned compaction during winter play; t h i s was e s p e c i a l l y serious on a practice green, one of those which were sampled i n these experiments. The practice green, greens No. 11 and 18, and a poorly drained part of the fairway near the practice green were sampled on October 27, and December 7 in 1962, and February 12, February 27, and March 14 i n 1963. 82 The arithmetic means of sod reserve indexes for the various sampling dates are given i n Table V.: Table V. Sampling date means (Exp. 6a) Sampling date Sod reserve index October 27 323.5 December 7 446.5 February 12 363.2 February 27 391.0 March 14 451.3 Using the Duncan's multiple range test the means were compared and the s t a t i s t i c a l l y s i g n i f i c a n t differences noted (Table VI): Table VI. Differences among; sampling date means (Exp. 6a) Sampling dates Differences March 14 minus October 27 128.3 ** " " " February 12 86.6 » » " February 27 60.8 " " " December 7 5.3 December 7 " October 27 123.0 ** " " " February 12 82.3 " " " February 27 55.5 February 27 " October 27 67.5 " » " February 12 27.3 February 12 " October 27 39.7 (Basic data and analysis of variance i n Annendix F.) 83 (b) Point Grev Golf and Country Club, This i s another lowland (Ladner s o i l series) course along the Fraser River, It i s about 30 years old, and i s a private club; therefore, the play i s not as heavy as on McCleery. Maximum number of rounds played per day does not exceed 250. Nevertheless, at thi s club, too, play goes on a l l year. Drainage i s a problem, espe c i a l l y during winter and early spring. Since the water l e v e l i n the Fraser River r i s e s and f a l l s with the t i d e , the drainage system on the course, which i s emptied into the r i v e r , i s usable only at low t i d e . Often the low l y i n g parts of the course are under water. The course i s managed by a superinten-dent with a l i f e long experience i n golf course operation. He commands a labor force of 5 permanent and 4 temporary men. F e r t i l i z e r i s used as follows: March 80 l b s . 6:8:6: f e r t i l i z e r per green A p r i l 80 " "Milorganite" " " June 30 " 6:8:6, mixed with 30 l b s . "Milorganite" per green July 10 " Ammonium n i t r a t e per 1000 sq. f t . October 20 " "Milorganite" per green November to March same as in October Greens are topdressed twice a year i n A p r i l and August. A mixture of 50 percent Nicholson loam and 50 percent sand i s applied at the rate of 1 cubic yard per green. Sprink-l i n g during summer season occurs 3 nights per week from 8 p.m. to 8 a.m. Mowing i s accomplished 2 to 6 times each week, de-pending on the season. Cutting at 3/8 of an inch for summer, 84 and 1/2 of an inch for winter i s customary. For disease control "Semesan" was applied at the rate of 1 pound per green in February, March, and June i n the current season. Although not recorded by the superintendent, anthracnose i n f e c t i o n was observed on greens Nos.3 and 15 at the f i r s t sampling of these greens on November 2, 1962. By the second sampling date, December 7, the disease had spread widely over these greens, but by the time of the t h i r d sampling date, February 12, the disease had cleared. Lime was not applied i n the current season. A e r i f i c a t i o n was undertaken i n March and June. V e r t i -cutting was performed once a month. To prevent compaction, temporary greens were used in January and February. The super-intendent was of the opinion that i n 1963 the greens looked better than usual. 2, December 7, 1962, and February 12, February 27, and March 14, 1963. The arithmetic means of sod reserve indexes on the various sampling dates are given i n Table VII.: Greens No. 3 , 14, and 15 were sampled on November Table VII. Sampling date means (Exp. 6b) Sampling date Sod reserve index November 2 199.5 December 7 313.5 February 12 241.3 February 27 March 14 150.5 135.0 85 The differences among means and the significance of these differences are given i n Table VIII.: Table VIII. Differences among sampling date means (Exp. 6b) Sampling dates Differences December 7 minus February 27 163.0 tt tr tt March 14 128.5 ft tt tt November 2 114.0 tt tt tt February 12 72.2 February 12 tr February 27 90.8 t» n tt March 14 56.3 tt tt n November 2 41.8 November 2 tt February 27 49.0 tt tt tt March 14 14.5 March 14 tt February 27 34.5 (Basic data and calculations are given i n Appendix 6) (c) Shaughnessy Golf and Country Club. This private course i s three years old. I t i s located close to the previous two courses near the Fraser River, but i t i s an upland course. The s o i l i s a sandy loam (Alderwood or Nicholson s o i l s e r i e s ) . The average number of plays i s estimated to be 100 rounds per day. This club, too, i s open for play a l l year around. The superintendent, with l i f e l o n g experience i n golf course manage-ment, has a labor force of 5 permanent and 5 temporary men. Other superintendents believe that t h i s course has the best t u r f i n the region. 86 F e r t i l i z e r i s applied according to the following schedule: March 120 l b s . 10:20:10 per green A p r i l f e r t i l i z e r , not s p e c i f i e d May- Sulphate of ammonia, quantity not recorded June 13:16:10 f e r t i l i z e r Tt August 40 l b s . Sulphate of ammonia per green September 120 l b s . 10:20:10 per green Topdressing i s applied 3 to 4 times per year with a mixture of 75 percent "good compost" and 25 percent f i n e sand, applied at the rate of 1.5cu. yds. per green. (This practice very probably i s the source of management troubles on t h i s course, f o r the frequent and heavy rate of topdressing and high proportion of organic matter i n the mixture results i n the formation of a tight layer on the sod.) There are no l i v i n g roots 3/4 of an inch below the surface. The organic matter i n the s o i l i s already high due to the presence of dead but undecomposed stolons between 1 and 2 inches below the surface. These stolons were planted there 4 years ago as a means of vegetative propagation of the very c a r e f u l l y selected strains of Highland bentgrass. The stolons were covered with s o i l , and produced a t u r f of excellent qua l i t y , unparalleled i n the Vancouver area. Unfortunately, the aforementioned topdress-ing practice seems to have i n i t i a t e d a decline i n the t u r f quality. Heavy thatch was quite obvious on the f i r s t sampling date, November 2, 1962, and v i s i b l y increased as the winter months passed. The t u r f peeled with even the most gentle p u l l i n g . 37 Spikes on the g o l f e r s 1 shoes, the bouncing of the b a l l s , even lawn mowers marred the putting green surface. V e r t i c u t t i n g i s done now twice a month, but i s not very e f f e c t i v e . I f anything, i t increases the roughness of the putting surface. A e r i f i -cation i s undertaken twice a month to accelerate the decompo-s i t i o n of inactive organic matter. The superintendent observed that the root growth i s so much accelerated around the holes that a day or two a f t e r the a e r i f i c a t i o n treatment the new roots f i l l i n the holes. The course has a good drainage system. Sprinkling i s applied 3 nights a week during the summer season. Mowing is done between 2 and 6 times per week, depending on the season. The cutting height i s unchanging, remaining 1/4 of an inch. Lime i s applied every other year at the rate of 50 pounds per green. The l a s t lime ap p l i c a t i o n was given i n A p r i l , 1962. Temporary greens are used when necessary,, although there were no temporary greens i n the winter when the experiments were conducted. According to the superintendent the good drainage system allows play at a l l times. Greens Nos. 12, 14, and 15 were sampled on November 10, December 7 i n 1962, and February 12, February 27, and March 14, 1963. The arithmetic means of the sod reserve indexes representing the various sampling dates are given i n Table IX.: 88 Table IX. Sampling date means (Exp, 6c) Sampling date Sod reserve index November 10 472.6 December 7 490.4 February 12 462.6 February 27 372.6 March 14 395.4 The differences among means and t h e i r s i g n i f i c a n c e are given i n Table X. Table X. Differences among sampling date means (Exp. 6c) Sampling dates Differences December 7 minus February 27 117,8 * " " " March 14 95 .0 " " " February 12 27.8 " " " November 10 17.8 November 10 11 February 27 100.0 " " " March 14 77.2 " " " February 12 10.0 February 12 " February 27 9 0 . 0 " " " March 14 67.2 March 14 " February 27 22.8 (d) The University Golf Course. This course i s located on the University Endowment Lands i n the West Point Grey area, an upland location with highly variable s o i l and drainage. 39 The club i s p r i v a t e l y owned and has operated as a public course for over 30 years. The superintendent i s reluctant to disclose figures on the number of rounds played per day or year. The course i s open f o r play a l l year around, but temporary greens are sometimes used during f r o s t y weather. While the experiments were conducted, temporary greens were i n use i n January and February, 1963. I t was noted at various sampling dates that the course was over-played. Signs of severe compaction were observed during the winter months, even while, according to the superintendent, temporary greens were i n use. The labor force consisted of 4 permanent and one temporary worker; t h i s was the smallest labor force of the four. F e r t i l i z e r was used as follows: Spring 120 l b s . 10:20:10 per green August « " " " " October 60 " " " " Twice a year a three gallon p a i l of ammonium ni t r a t e is given each green; time of application varies with the weather. Topdressing i s given i n the spring, but the amount or kind of topdressing material was not recorded. Prior to topdressing, a e r i f i c a t i o n i s undertaken i n the spring. Lime i s applied every other year. On the f i r s t sampling date, November 13, 1963, lime had been applied, and, i n the writer's view, the quantity applied was excessive. According to the superintendent, 4 buckets of a g r i c u l t u r a l lime were applied per green. Mowing of greens varied between 2 and 5 times per 90 week depending on the season; mowing height varied between 3/16 and 3/4 of a n inch. Sprinkling was undertaken 3 nights per week during the summer. Drainage of most greens i s poor; the greens were saturated at every sampling date. No fungi-cides or weedkillers were applied i n the current season. 13, and December 7 i n 1962, and February 12, February 27, and March 14 i n 1963. Arithmetic means of sampling date sod reserve indexes are given i n Table XI.: Greens Nos. 6, 8, and 11 were sampled on November Table XI. Sampling date means (Exp. 64) Sampling date Sod reserve index November 13 233.8 December 7 241.6 February 12 115.0 February 27 157.4 March 14 205.1 The differences between the arithmetic means of the indexes for the f i v e sampling dates are given i n Table XII.: 91 Table XII. Differences among sampling; date means (Exp, 6d) Sampling dates Differences December 7 minus February 12 126.6 Tt n tr February 27 84.2 tt tt rr March 14 36.5 tt rr rr November 13 3 .6 November 13 February 12 123.0 t! tt » „ February 27 80.6 tt rr tt March 14 32.9 March 14 February 12 90 .1 rr tt February 27 47.7 February 27 February 12 42.4 Although sod reserve index was found to vary to a great extent from core to core and from green to green within each golf course, the indexes tended to be c h a r a c t e r i s t i c of the i n d i v i d u a l golf course as can be seen i n the accompanying graphs (Fig, 6 ) . The graph , based on the arithmetic means of sod reserve indexes obtained with 5 sampling dates, shows that the sod reserve indexes tend to characterize a golf course and also shows para l l e l i s m i n the seasonal behaviour of the indexes. P i g . 6 S e a s o n a l v a r i a t i o n s i n t h e s o d r e s e r v e i n d e x o f g r e e n s a t f o u r V a n c o u v e r a r e a g o l f c o u r s e s . 92 (7) Experiment 7 was undertaken to study the l o c a l i -zation of reserves i n the underground organs of turfgrasses with the same but by now more competently handled technique as i t was used i n experiments 3 and 4. In addition, the responses of several species of turfgrasses to the technique were studied. The cores i n t h i s experiment, and also i n Exp. 8, were taken from the experimental t u r f plots of the University of B r i t i s h Columbia. The plots were established i n the f a l l of I960 on a sandy loam s o i l of the Nicholson s e r i e s . Before sowing, ground limestone had been applied at the rate of 1000 pounds per acre. F e r t i l i z e r was applied at the rate of 1200 pounds of 8:10:6 per acre on September 8, I960. On September 9, I960, the plots were established to pure stands of the following species: Chewings fescue 1 pound per 150 square feet Highland bentgrass 1 " " 3 5 0 " " Merion K. bluegrass 1 " " 200 " " Perennial ryegrass 1 " " 100 " " After seeding, the area was covered with peat moss l/U of an inch thick. Subsequent f e r t i l i z e r applications were the following: A p r i l 7, 1961 800 pounds of 10:20:10 per acre September 14, 1961 900 " " " " " 93 May 14, 1962 800 pounds of 10:20:10 per acre October 12, 1962 400 " " " " " A p r i l 24, 1963 700 " " 8:10:6 » " For weed control 2-4 D was applied once a year. No fungicides were applied. Overhead i r r i g a t i o n was provided with an under-ground i n s t a l l a t i o n of rotary type s p r i n k l e r s . The amount of water and the frequency of application varied as required for optimum growth. Mowing practices followed the pattern of home lawn management, mown at the height of 3/4 of an inch or 1 inch where or when necessary, every 10 to 14 days or as often as required. A rotary type mower was used. To remove thatch v e r t i c u t t i n g was undertaken with a "Reno-thin" machine on A p r i l 11, 1963. The plots were abandoned for experimental uses soon a f t e r seeding because of the imminence of construction i n the area; for "appearance sake" the plots were maintained as "lawn". Cores f o r experiment No. 7 were sampled on May 7, I 9 6 3 . Each of the cores of the 4 species of t u r f grasses were trimmed to 4 lengths, v i z . 4, 2, 1, and 1/2 inches. The design was such that a 4 x 4 f a c t o r i a l analysis could be undertaken. The cores shorter than 4 inches were placed on wooden supporting platforms of various heights, f i t t e d into the cylinders so that the surface of the t u r f core remained 1/2 of an inch below the 94 brim of the containing cylinder. Holes were d r i l l e d through the wooden blocks to aid drainage. Each treatment was repeated 6 times, thus the t o t a l number of cores was 96. The cores remained i n the dark from May 7 to June 6; they were harvested at ten day intervals on May 17, May 27, and June 6, 1963. It was found that the perennial ryegrass did not produce growth a f t e r the f i r s t harvest; therefore, i t was omitted from the analysis of thi s experiment. Arithmetic means of treatments, based on the t o t a l s of 3 harvest dates and 6 r e p l i c a t i o n s are given i n Table XIII.: Table XIII. Treatment means (Exp. 7) A. Species B. Core lengths 1/2" 1" 2" 4" A. Means Fescue 81.8 116.3 161.5 133 .6 123.4 Bentgrass 125.5 159 .8 205.8 165.0 164.0 Bluegrass 171.8 216.6 262.8 296.5 236.9 B. Means 126.3 164.4 210.0 198.3 174.8 The analysis of variance (Appendix J) showed highly s i g n i f i c a n t differences attributable to both species and core length, but no si g n i f i c a n t i n t e r a c t i o n s . Treatment differences are given i n Table XIV.: 95 Table X I V , T r e a t m e n t mean d i f f e r e n c e s ( E x p . 7) A . S p e c i e s D i f f e r e n c e s C . C o r e L e n g t h D i f f e r -B l u e g r a s s - F e s c u e = 113.0 * * e n c e s W i t h i n S p e c i e s B l u e g r a s s - B e n t g r a s s = 72.9 ** £ § I S i £ i 2 " " V 2 " - 79.7 ** O t h e r d i f f e r e n c e s n . s B e n t g r a s s - F e s c u e = 40.1 B e n t g r a s s : 2" - 1/2" = 80.3 * B. C o r e l e n g t h D i f f e r e n c e s 0 t h e r d i f f e r e n c e s n . s 2" - 1/2" = 83.7 * * B l u e g r a s s : 4" - 2" = 33.7 2" - 1" - 45.6 V' - 1" = 79.9 ** 2" - 4" = 11.7 4 " " 1 / 2 " = 1 2 4 ' 7 4" - 1/2" = 72.0 * ' 2 " - 1 " = ^ 6 ' 2 4« - i « - 33.9 2" - 1/2" = 91.0 1" - 1/2" = 38.1 ! " " V 2 " - 44.8 The d i f f e r e n c e s b e t w e e n t h e s o d r e s e r v e i n d e x e s o f M e r i o n K e n t u c k y b l u e g r a s s and t h e o t h e r t w o s p e c i e s w e r e h i g h l y s i g n i f i c a n t . The d i f f e r e n c e b e t w e e n c h e w i n g s f e s c u e a n d h i g h l a n d b e n t was n o t s i g n i f i c a n t . D u n c a n ' s m u l t i p l e r a n g e t e s t s h o w e d h i g h l y s i g n i -f i c a n t d i f f e r e n c e s b e t w e e n 2 i n c h e s a n d 1/2 o f a n i n c h t r e a t -m e n t s , a n d s i g n i f i c a n t d i f f e r e n c e s b e t w e e n i n d e x e s f o r t h e 4 i n c h a n d 1/2 i n c h c o r e l e n g t h s . O t h e r d i f f e r e n c e s w e r e n o t s i g n i f i c a n t . S i n c e t h e s e c o m p a r i s o n s w e r e made b e t w e e n c o r e l e n g t h i n d e x m e a n s , w h i c h w e r e t h e a v e r a g e s o f t h e t h r e e s p e c i e s c o r e l e n g t h m e a n s , t h e c o m p a r i s o n m i g h t h a v e b e e n o b s c u r e d b y v a r i a b l e s p e c i e s r e s p o n s e t o c o r e l e n g t h t r e a t m e n t s . T h e r e was some i n t e r a c t i o n e f f e c t b e t w e e n t h e t w o f a c t o r s w h i c h i n d i -c a t e s t h a t a n o b s c u r i n g e f f e c t c o u l d e x i s t , e v e n t h o u g h t h e F 96 value for i n t e r a c t i o n was not s i g n i f i c a n t s t a t i s t i c a l l y . Since the available data also allowed treatment to treatment comparisons within each of the three species, these were calculated and presented under "C" i n Table XIV. In t h i s analysis, too, the fescue and bent grasses show remarkable s i m i l a r i t y , v i z . a highly s i g n i f i c a n t difference between 2 inch and 1/2 inch treatments, other differences being non-significant. Blue-grass showed highly s i g n i f i c a n t differences between 4 inch and 1/2 inch, between 4 inch and 1 inch, and between 2 inch and 1/2 inch treatments. (8) Since the study of l i t e r a t u r e made i t clear that carbohydrate storage i s not e n t i r e l y confined to the under-ground organs of grasses, and inasmuch as the crown or stubble part of grasses i s of significance i n food storage, i t seemed desirable to conduct an experiment which.would test whether or not the sod reserve index determination would be greatly i n -fluenced by c l i p p i n g the e t i o l a t e d tissues at d i f f e r e n t heights and frequencies. I f the food reserves stored i n the above ground organs are s i g n i f i c a n t , then i t may be important to know how the mowing height and mowing frequency a f f e c t the reserves. Cores of Merion Kentucky bluegrass were obtained from the university t u r f plots on July 2, 1963. The following treatments were: applied: Clipping heights, 0 .5 and 1.5 inches Clipping frequencies, 1, 2, 3, and 6 times i n 6 weeks 97 The c l i p p i n g height and cl i p p i n g frequency treat-ments were combined f o r a 2 x 4 f a c t o r i a l analysis. Each treatment was repeated 6 times. On the l a s t c l i p p i n g date, on August 13, 1963, a l l cores were harvested at the 0.5 inch l e v e l so that a l l new growth since the beginning of dark treatment, could be accounted f o r . As i t turned out, however, an error had been made when c l i p p i n g a l l the cores of the control (one harvest at the end of 6 weeks) at the 0.5 inch l e v e l , thus leaving one c l i p p i n g height treatment out of the f a c t o r i a l arrangement. For t h i s reason the data (Appendix K), were analyzed as a 2 x 3 f a c t o r i a l instead of the intended 2 x 4 , the 3 l e v e l s of clipping frequency containing 2, 3, and 6 clippings i n 6 weeks. Another, a non f a c t o r i a l analysis, was made to include the 1 c l i p p i n g frequency at 0.5 inch height treatment; t h i s analysis was carried out as a simple analysis of variance with 7 treatments. It should be noted that cores i n t h i s experiment were i n darkness f o r 42 days, a longer period than those f o r cores i n other experiments. The reason lay i n the fact that Merion Kentucky bluegrass continued to grow longer than the other grasses. Treatment means of sod reserve indexes obtained a f t e r 42 days growth are given i n Table XV.: 98 Table XV, Sod reserve Indexes for Merion Kentucky blue-grass clipped at two heights and four frequencies Frequency Clipping height (inches) over s i x weeks n c •, c 1 500 2 524 490 3 546 489 6 599 491 The f i r s t analysis of variance ( f a c t o r i a l ) showed a highly s i g n i f i c a n t F f o r height differences but the second analysis (7 treatments) did not y i e l d a s i g n i f i c a n t F value, (The explanation probably l i e s i n the obscuring e f f e c t s , the frequency variance, and the i n t e r a c t i o n variance.) The s t a t i s t i c a l l y s i g n i f i c a n t mean differences are given i n Table XVI.: Table XVI. S i g n i f i c a n t treatment mean differences (Exp. 8) Treatment means Difference 599 minus 489 110 * 599 " 490 109 * 599 " 491 108 * 599 " 500 99 * In other words, cl i p p i n g six times i n six weeks at 0.5 inches produced a s i g n i f i c a n t l y higher sod reserve index than c l i p p i n g at any frequency at 1.5 inches, or c l i p p i n g once at 0.5 inches. 99 (9) In t h i s experiment, and i n the next one, reserves under summer c o n d i t i o n s were studied i n f i e l d p l o t s . Portable dark chambers were constructed and placed over f i e l d p l o t s to study the exhaustion of reserves under quasi f i e l d c o n d i t i o n s . Two sets of these chambers were made, each c o n s i s t -ing of two u n i t s , an inner chamber to exclude l i g h t , and a l a r g e r , t e n t - l i k e s t r u c t u r e , placed over the f i r s t u n i t to reduce heat accumulation. Frames were constructed of 2" x 2" lumber and black polyethylene sheets. Dimensions of the inner u n i t were as f o l l o w s : o v e r a l l l e n g t h , 10 f e e t ; width, 4 f e e t ; height, 27 inches. The a c t u a l experimental area under the u n i t was 6 x 4 f e e t . The 2 fe e t e x t r a length at each end, which add up to the t o t a l of 10 f e e t , i ncluded the l i g h t t r a ps which allowed a i r movement through the dark chamber but no l i g h t entry. The base of the frame rested on a ground frame, made of 2 x 4. The ground frame was lowered i n t o the sod at the beginning of the experiment and remained there. The dark chamber, which f i t t e d i n t o the ground frame i n such a way that l i g h t could not enter along the l i n e of contact, was o c c a s i o n a l l y removed f o r i n s p e c t i o n , harvest, and f o r overnight s p r i n k l i n g . The outside u n i t was 14 fe e t long, 6 f e e t and 3 inches wide. The height of i t s v e r t i c a l w a l l was 33 inches, upon which was a 20 inch high s l o p i n g r o o f . This s t r u c t u r e was a l s o covered with dark polyethylene, except at the two ends and from the ground t o 18 inches high along the sides t o permit a i r c i r c u l a t i o n . Figure No. 7 shows the dark chamber and the canopy i n the f i e l d . 100 Fig, 7. l o r t a b l e dark chamber in the f i e l d The chambers were placed on the experimental tur f plots at U.B.C. which were described e a r l i e r . Highland bent and perennial ryegrass plots were used i n th i s experiment which started on June 2 5 ; plots were harvested a month l a t e r , on July 2 5 , 1 9 6 3 . P a r a l l e l with the dark treatment, control plots receiving normal l i g h t were marked out and harvested at the end of the experiment. Basic data and calculations are presented i n Appendix L. Data are presented i n grams/square foot. The perennial ryegrass did not produce appreciable growth in the dark. The few ryegrass shoots which managed to survive and grow could not be taken into account because i n -truders from adjacent plots, mostly Kerion Kentucky bluegrass 101 and some Chewings fescue and Highland bent grasses, c o n s t i -tuted more than half of the scarce growth under the dark chamber. The control plot of ryegrass produced more than twice the dry matter of the bentgrass control, v i z . 5.75 and 2.62 grams per square foot respectively. The y i e l d of the eti o l a t e d Highland bent grass was 63 percent more than the dry weight of the l i g h t control, v i z . 4.27 and 2.62 grams per square foot. (10) This was another f i e l d experiment with the previously described dark chamber. This time Merion Kentucky bluegrass, mown closely before the t r i a l started, was used. In one t r e a t -ment the "dark" and " l i g h t " plots were harvested on the 10th and 20th days and i n the other treatment the "dark" and " l i g h t " plots were harvested on the 20th day. Only one of the dark chambers was used t h i s time. The area under the chamber was divided into 4 sub-plots, 2 x 3 feet each, to provide 2 r e p l i -cations for both c l i p p i n g frenuency treatments. Another blue-grass area, receiving f u l l l i g h t , was marked out for control plot, containing 4 subplots of 2 x 3 feet. Dark treatment started on July 27, 1963; harvest dates were August 6 and 16. The data and calculations f o r t h i s experiment are presented i n Appendix M. The arithmetic means of treatments are given in Table XVII.: 102 Table XVII, Treatment means f o r experiment 10 (gms/sq. f t . ) B. Clinping frequency treatments A. Light treatments Cut once Cut twice Natural l i g h t 9.12 8.42 No l i g h t 8.40 3.41 Differences between the means are not great, although, grass grown under natural l i g h t produced s l i g h t l y more dry matter than that grown i n darkness, a response to be expected o n i* P r i o r i grounds. Also s l i g h t l y more dry matter was prodticed from plots cut once, again a response to be expected on a p r i o r i grounds. 103 IV. DISCUSSION The vigour of turfgrass under normal growth con-ditions and i t s s u r v i v a l under stress conditions, such as drought, extreme temperatures, severe d e f o l i a t i o n , insect and disease attack, and competition from weeds, has been shown i n a number of studies to be associated with the amount of "food reserves" accumulated by the grass plant. Although t h i s knowledge has been available f o r two or three decades, i t s significance, i t appears,.is not yet f u l l y appreciated. Intensive studies to investigate the effects of management practices, and edaphic, cli m a t o l o g i c a l and genetical factors i n the accumulation of "reserves" do not appear to have been made. Funds and time are rarely available f o r the time-honoured techniques. The simpler techniques used i n this study are not unduly expensive of time or funds. The f i r s t attempts to determine indexes were explora-tory. It was quickly ascertained that the common greens' plugger was an unsatisfactory t o o l ; the to o l ultimately developed possessed many obvious advantages over equipment used by other workers. The chief obstacle to i t s use would be stony s o i l . V a r i a t i o n among re p l i c a t e cores obtained with the t o o l was reduced somewhat with practice. The high inherent v a r i a b i l i t y of turf i n the f i e l d - attributable to variations 104 in s o i l , species, l i g h t and disease fa c t o r s , and to in e q u a l i -t i e s i n management - i s a major but unavoidable obstacle. Admittedly, some improvement i n the control of error could be gained by obtaining reserve indexes from cores placed i n dark chambers with better temperature, moisture and humidity controls. The sod reserve index means of the f i r s t experiment show an association between the amount of l i g h t and the accumu-l a t i o n of reserves; the lowest reserve index was obtained from a lawn with heavy shade (location "A"); well kept lawns i n f u l l sun (locations "C" and "D"), produced indexes about four times as high as " A ™ s . I t may be said that the lawn with the lowest index, 52 mgs. at "A", looked just as good, i f not better than the lawns with high indexes. It i s suggested that good t u r f quality i s not always associated with high reserves; i t should be r e c a l l e d however, that lawn "A" was more intensively managed than the others. Had lawn "A" received the same management treatments as "C" and "D", i t may well have been a poor lawn. Lawn "B", which received the least attention as f a r as manage-ment i s concerned, produced higher index (by 60%) than "A" due to i t s more favourable exposure to l i g h t . The l i g h t influence on reserve accumulation i s obscured when "C" and "D" are compared. While "C" produced 145.0 rngs., "D" gave 214.5 mgs., even though the di r e c t sunshine i t received d a i l y was 4 hours less than that received at "C". The explanation may be that the "C" l o c a t i o n was i n the path of student t r a f f i c and the compaction was l i m i t i n g the accumulation of reserves. 105 Another factor which contributed to the higher index at "D" was the fact that not being i n a "prestige" location, i t may have "suffered" occasional neglect i n maintenance at peak work periods, v i z . less s p r i n k l i n g and mowing. Since excessive and frequent s p r i n k l i n g and mowing deplete reserves, i t i s quite probable that the occasional "neglect" benefitted lawn "D". The intensive management practices may have added to the effects of shade i n slowing the accumulation of reserves which gave lawn "A" a low index. It was mentioned previously that t h i s lawn received bi-monthly f e r t i l i z e r applications, weekly mowings and sprink-l i n g every other day. Such practices would tend to deplete reserves even i n f u l l sunlight. The l i m i t i n g effect of shade on the accumulation of reserves was also obvious i n the f i f t h experiment where the sod reserve index obtained from the cores of heavily shaded plots was only 70 percent of the index produced by the less shaded p l o t s . Although the l i m i t i n g effect of shade on the accumu-l a t i o n of reserves i s to be expected under many circumstances, the findings of these preliminary experiments showed that the' method i s sensitive enough to reveal differences i n sod reserve indexes caused by various l i g h t conditions. The demonstration of differences i n sod reserve 106 i n d e x e s a t t r i b u t a b l e t o f e r t i l i t y d i f f e r e n c e s was not s u c c e s s f u l perhaps as a r e s u l t o f t h e 10 weeks l o n g t ime l a g between t h e a p p l i c a t i o n of f e r t i l i z e r and t h e t i m e o f c o r i n g . S p r i n k l i n g and r a i n may have l e a c h e d much o f the f e r t i l i z e r which was not removed by the l u s h growth i n i t i a t e d by t h e f e r t i l i z e r a p p l i c a t i o n . The u s e f u l n e s s o f t h e sod r e s e r v e i n d e x as a r e f l e c -t i o n o f e c o l o g i c a l d i f f e r e n c e s and management c o n d i t i o n s i s apparent i n F i g u r e 6 where the f l u c t u a t i o n s o f sod r e s e r v e i n d e x e s o f t h e greens o f f o u r g o l f c o u r s e s are p l o t t e d o v er a p e r i o d o f f i v e months. The r a t i n g s t o be accorded th e f o u r g o l f c o u r s e s a r e as f o l l o w s : 1. Shaughnessy 2 . M c C l e e r y 3. P o i n t Grey k. U n i v e r s i t y T h i s o r d e r , based on t h e g r a p h s , c o r r e s p o n d s w i t h t h e o r d e r i n which t h e s e g o l f c o u r s e s a r e r a t e d s u b j e c t i v e l y a c c o r d i n g t o p u t t i n g g r een q u a l i t y . The i n t e n s i t y o f manage-ment r a t i n g s a r e i n t h e same o r d e r . The p a r a l l e l b e h a v i o r o f t h e sod r e s e r v e i n d e x e s from th e f o u r c o u r s e s i s n o t a b l e . The d e c l i n e o f sod r e s e r v e s i n the e a r l y s p r i n g which i s l a t e r f o l l o w e d by an i n c r e a s e , may be e a s i l y e x p l a i n e d on the most p r o b a b l e b a s i s t h a t t h e g r a s s draws h e a v i l y on i t s r e s e r v e s d u r i n g s p r i n g r e c o v e r y . 107 The Shaughnessy course led the others on the basis of subjective judgments as well as in sod reserve index. A thatch problem, no doubt, w i l l eventually, and probably soon, become a serious obstacle i n play, and the t u r f quality may decline. The course i s r e l a t i v e l y new. McCleery, also a r e l a t i v e l y new course, produced sod reserve indexes almost as high as those of Shaughnessy during the f a l l , and surpassed Shaughnessy on the l a s t two sampling dates. This excellence of the greens i n t h i s course i s even more remarkable when the heavier play on t h i s public course i s taken into consideration. Compaction was a noticeable factor on the University course. Yet on the l a s t two sampling dates i n the spring, i t , too, produced s l i g h t l y higher sod reserve indexes than the somewhat superior Point Grey course. It may be speculated that compaction, a condition- on golf courses and other sports t u r f s , i s conducive to the build up of reserves i n early spring and hence accelerates spring recovery. This may be explained by the better heat conductivity of compacted s o i l , which allows fa s t e r thawing and e a r l i e r resuming of growth a c t i v i t i e s . Meteorological records at the University of B r i t i s h Columbia Weather Station show ground f r o s t 4 inches deep between January 11 and February 4. Thus the thawing i n the region of core depth was completed 8 days prior to the t h i r d sampling date a f t e r which the growth a c t i v i t i e s of grass increased. The temperature, however, was s t i l l beloxv that of the optimum fo r photosynthesis, 108 thus causing the grass to draw upon i t s reserves. On the compacted s o i l , because i t warmed more quickly, photosynthesis could have started e a r l i e r , thus allowing some accumulation of reserves or just providing enough carbohydrates f o r current growth and preserving previously accumulated reserves. Another possible explanation for the r e l a t i v e l y higher sod reserve index obtained from the compacted s o i l i s that, contrary to the above elaborated theory, the beginning of spring growth was delayed on the compacted s o i l , thus the reserves accumulated the previous f a l l remained unused while they were u t i l i z e d i n the early growth of grass on the less compacted s o i l . The high sod reserve index of the Shaughnessy greens, where root growth only occurs i n the upper 3/4 of an inch of the s o i l , i s inconsistent with the conventional concept of the role roots play i n the l i f e of t u r f grass. It i s customary to stress the importance of grass roots found i n the upper 6 inches of the s o i l p r o f i l e . Yet the observations on the greens of Shaughnessy course show that the grass i s able to store a l l the reserves i t needs i n the upper 3/4 of an inch of the s o i l p r o f i l e - and perhaps above the s o i l l e v e l . This observation conforms with the r e s u l t s of other i n q u i r i e s into the l o c a l -i z a t i o n of reserves made by t h i s author; experiments 3, 4, and 7 were undertaken to study the l o c a l i z a t i o n i n the s o i l horizon, and one of the objectives of experiment 8 was the study of l o c a l i z a t i o n i n the above-ground portion of the grass. 1 0 9 The r e s u l t s of the second and t h i r d experiments indicate that most of the reserves, or rather, most of the determinable reserves expressed i n the terms of sod reserve index, are located i n the storage organs of the grass which are i n and above the upper one inch of the s o i l horizon. This conclusion i s based on the evidence that a one inch thick s l i c e of sod produced a sod reserve index which was not s i g n i f i c a n t l y lower than the indexes produced by longer core lengths. Because the conclusion based on the results of the second and t h i r d experiments may modify somewhat our knowledge about t u r f grass and t u r f grass roots, and because i t may also a f f e c t conventional management practices, i t seemed desirable to confirm t h i s finding by an additional investigation, experiment 7. Experiment 7, unlike i t s predecessors 2 and 3, core showed highly s i g n i f i c a n t differences between Alengths. This, however, does not contradict the findings of the previous experiments. Only the 1/2 inch treatment, which was not applied i n the previous experiments, produced sod reserve indexes highly s i g n i f i c a n t l y lower than the other treatments. These re s u l t s support the view that, of the reserves stored underground, only those located i n the upper one inch of the s o i l horizon are s i g n i f i c a n t in r e u t i l i z a t i o n . This, of course, does not imply that i n water uptake and nutrient uptake deeper roots might not be of importance; nor does i t mean that the results can be extended to pasture and hayland t u r f . 110 Experiment 7 indicated that there are differences among species of grasses i n regards to the amount of reserves they accumulate. Although t h i s i s not a f i r s t record, i t i s confirmatory and i t shows that the reserve index method i s able to detect such differences. Merion Kentucky bluegrass behaved d i f f e r e n t l y r e l a t i v e to reserve accumulation than the other two species; the difference was not s i g n i f i c a n t between Chewings fescue and Highland bentgrass. It was also revealed that species also d i f f e r i n the l o c a l i z a t i o n of reserves. While chewings fescue and highland bent grasses have most of t h e i r determinable sod reserves i n the upper one inch of the s o i l horizon, Merion Kentucky bluegrass, on the other hand, produces most of i t s determinable sod reserves from the upper two inches of the s o i l horizon. Perennial ryegrass performed very poorly in the dark, producing no new growth a f t e r the f i r s t harvest, and the data were omitted from the analysis of experiment 7 to avoid d i s t o r t i o n i n the comparison of the other three species. There are several possible explanations for the f a i l u r e of ryegrass to produce growth i n the dark a f t e r the f i r s t harvest. One cause could be that t h i s species has less reserves than the other grasses, and hence exhaustion takes place sooner. Another cause may be that c l i p p i n g injury prevented further growth even though there might have been enough reserves to support such growth. This injury could have originated when the ryegrass was mown to uniform height with the other species Il l i n the f i e l d p r i o r to core sampling, or a f t e r the 10 days growth i n dark when the etiolated grass was clipped at 1/2 inch height. It i s possible that t h i s low c l i p p i n g removed either important above-ground storage organs or i t removed the meristematic tissues necessary for continuation of growth. Since one accompanying effect of e t i o l a t i o n i s the elongation of internodes, the meristems of e t i o l a t e d grass are higher than usual and, therefore, are l i k e l y to be removed when clipped a f t e r a period of growth i n dark. It may be r e c a l l e d observed that Maeda (1961) and Ehara and Maeda ( 1 9 6 l ) A i n c lipping that studies with I t a l i a n ryegrass^the f i r s t c l i p p i n g caused more loss of reserves i n the roots and stubble than subsequent clippings. They also noted that a f t e r c l i p p i n g a rapid reduc-t i o n i n the quantity of root and stubble reserves took place, the reduction being greater i n the stubble than i n the roots. It may be reasonably concluded that damage to reserve storing organs, e s p e c i a l l y the p a r t i a l removal of the stubble was a factor, or one of the factors, i n the growth stoppage of rye-grass a f t e r the f i r s t harvest i n dark. There i s s t i l l another possible cause for the growth f a i l u r e , v i z . the lack of l i g h t or other conditions associated with the dark room. In experiment 9 where two plots of ryegrass were mown at the same height, 3/4 inch, p r i o r to dark treatment, and one was covered with the f i e l d dark chamber, and the other remained i n f u l l l i g h t . I f pre-dark mowing injured the grass seriously then both plots should have f a i l e d to produce growth. This, however, was not the case, f o r only under the dark treatment the growth of grass 112 stopped, while there was a successful recovery i n the l i g h t ; i n f a c t , the y i e l d was greater than from a s i m i l a r l y treated bentgrass pl o t . The result suggests that not c l i p p i n g but rather the dark treatment was the more detrimental factor i n t h i s experiment. I t i s the opinion of t h i s author that low c l i p p i n g and the dark treatment are both detrimental to the growth of ryegrass i n dark. Although higher c l i p p i n g height would help t h i s grass to continue growth, i t s growth response to dark i t s e l f prevents i t s use i n sod reserve index determi-nation. Although the height of c l i p p i n g appeared to be a c r i t i c a l f a c t o r with ryegrass, i t was found (Exp. 8 ) , that c l i p p i n g height at the 1/2 of an inch l e v e l i s not detrimental to the growth of Merion Kentucky bluegrass. Clipping at t h i s height produced more growth with a l l c l i p p i n g frequencies, ranging from weekly clippings to cl i p p i n g once i n 6 weeks, than clipping at 1.5 inches. This also indicates that the important stubble reserves of t h i s grass are below the 1/2 of an inch c l i p p i n g l e v e l . It i s in t e r e s t i n g to note that c l i p p i n g frequency treatments produced s l i g h t l y more growth with increasing c l i p p i n g frequency. Graber and Ream (1931), Harrison (1931), Darrow (1939), Spencer et a l . (1949), Juska (1955), Juska and Hanson (1961), Sull i v a n (1962) came to the conclusion that lower mowing heights were detrimental to the development of Poa  pratensis . decreased i t s reserves and y i e l d more than higher 113 c l i p p i n g h e i g h t s . I t i 3 w e l l t o point out, however, th a t these workers stud i e d the performance of bluegrass over long periods of time, some of them f o r s e v e r a l years, under the various mowing p r a c t i c e s , while the r e s u l t s of experiment 8 were a r r i v e d at a f t e r 42 days growth period i n the dark chamber. Frequent mowing or c l i p p i n g was a l s o found to be d e t r i m e n t a l to the development of the grass by most authors already quoted, yet experiment 8" d i d not show s i g n i f i c a n t d i f f e r e n c e s among c l i p p i n g f r e q u e n c i e s . There i s at l e a s t one author whose r e s u l t s c o n t r a d i c t the f i n d i n g s of the p r e v i o u s l y quoted workers. Madison (1962 d) reported that the y i e l d of Seaside and Highland bent grasses increased with short and frequent mowing. Views expressed by the m a j o r i t y of workers support the f i n d i n g s of t h i s r e p o r t . A l l other f a c t o r s being equal, frequent and clo s e mowing of t u r f g r a s s tends to exhaust i t s reserves more q u i c k l y than l e s s frequent mowings at higher l e v e l s . I t i s f a i r t o point out, however, that these terms "low" and "high", frequent and infrequent mowing are r e l a t i v e terms and t h e r e f o r e s u s c e p t i b l e to misleading i n t e r p r e t a t i o n s . In Madison's report frequent mowing meant 5 mowings per week, infrequent mowing was one mowing per week. In the author's own experiment frequent mowing meant one mowing per week as compared with l e s s frequent mowings at 2, 3, and 6 weeks i n t e r v a l s . Roberts and Bredakis (I960) reported that a t u r f mowed f r e q u e n t l y at moderate heights produced more y i e l d than 1 1 4 when mown infrequently; infrequent mowing i n thi s case meant one or two mowings per year! I f f a l l a c i o u s conclusions are to be avoided one should r e f r a i n from the l i b e r a l use of the above mentioned terms. There are, however, s t i l l other, and not so e a s i l y avoided, factors leading to contradictory conclusions. Bio-l o g i c a l factors, such as the d i f f e r e n t i a l response of the various species, v a r i e t i e s , and strains of turfgrasses to cl i p p i n g treatments may lead to opposing r e s u l t s v/hen variable taxa are compared. Environmental factors often inte r f e r e with the research and may reverse r e s u l t s of c l i p p i n g treatments. Madison's (1962 b) observation well i l l u s t r a t e s t h i s point. He found that, although low mowing increased the y i e l d of Seaside and Highland bents, t h i s treatment lowered the y i e l d of Seaside during the hot months of May-June while Highland maintained i t s y i e l d . To ensure the success of future experiments involving sod reserve index determination, pre-treatment t r i a l s should determine the v a r i a b i l i t y of the experimental t u r f . Further-more, core sampling should be avoided during c r i t i c a l periods when the t u r f ' s performance i s not the usual due to drought and other environmental conditions. It is d i f f i c u l t to a n t i -cipate when such periods w i l l occur; nevertheless, there are certain regular, seasonally recurring conditions which can be predicted, such as winter dormancy and spring regrowth, when the sod reserve index may not be used r e l i a b l y for the purpose 115 of comparison with sod reserve indexes obtained during favorable growth periods. Summer dormancy of t u r f i s another period when c l i p p i n g or other treatments could produce unex-pected sod reserve indexes. Summer dormancy of turf i s seldom mentioned and an explanation i s rar e l y attempted by tu r f experts. When an explanation i s offered i t i s usually based on the theory that high summer temperature, usually but not necessarily occurring with drought, decreases growth rate by l i m i t i n g the water up-take. There i s good reason to believe that the problem i s more complex than t h i s explanation seems to imply. High temperature may l i m i t many other metabolic a c t i v i t i e s besides water uptake. Furthermore, temperature might not be the only factor causing dormancy in summer. In experiment 9, Highland bent produced 4.27 gms dry matter i n the dark from June 25 to July 25, while the control receiving normal sunlight produced only 2.62 gms, a rather low fi g u r e . Normally the control plots should produce more dry matter than the dark treatment. I t appears that there was some fact o r l i m i t i n g the production of dry matter i n the control. The most obvious explanation i s , of course, the l i m i t i n g effect of l i g h t . I t i s possible that, together with temperature, l i g h t plays some kind of ro l e i n c o n t r o l l i n g summer dormancy; perhaps a photoperiodic response mechanism i s the governing f a c t o r . The long day conditions p r e v a i l i n g in June-July might have indiced the dormancy in Highland bent grass. Another p o s s i b i l i t y i s that the surface temperature of the grass leaves was lower i n the dark than i n the l i g h t even 116 though the a i r temperature in the dark chamber was approxi-mately the same as outside. The higher l e a f surface temper-ature i n l i g h t might have caused the loss of carbohydrates through increased r e s p i r a t i o n or tra n s p i r a t i o n or both. It i s probable that grasses d i f f e r i n t h e i r dormancy responses to s i m i l a r temperature and/or l i g h t conditions. While dormancy was quite obviously demonstrated i n experiment 9 with Highland bent grass, dormancy was not so c l e a r l y observed i n experiment 10 with Kentucky bluegrass. The control plot of bluegrass yielded the same with two harvests at ten days i n t e r -val or s l i g h t l y higher with one harvest a f t e r 20 days than did the dark treatment. Since the r e s u l t s are sim i l a r , the occurrence of dormancy i s not as c l e a r l y demonstrated as i n experiment 9 , but the f a i l u r e of the control to outyield dark treatment to a greater extent proves that there was a dormancy. I t i s int e r e s t i n g that the summer dormancy of t u r f grass can be reversed by the exclusion of l i g h t . Further research w i l l be necessary to investigate the length of dark treatment necessary to break dormancy. I t i s also necessary to determine the l e v e l of l i g h t i n t e n s i t y where the breaking of dormancy takes place; the complete exclusion of l i g h t may not be necessary to break dormancy. This research would have a great si g n i f i c a n c e f o r p r a c t i c a l t u r f management, for i t may lead to the development of a technique which would allow the regulation of dormancy at w i l l . There may be certain ad-vantages i n inducing or stopping dormancy i n p r a c t i c a l t u r f 117 culture. I f an unusually cold and moist summer and autumn weather produces abundant vegetative growth at the expense of "reserve food" the overwintering and spring recovery of grass w i l l be poor. To avoid the depletion of reserves i n such weather i t may be necessary to curb vegetative growth by a r t i f i c i a l l y inducing dormancy when the natural conditions are not favourable to "spontaneous" dormancy. Stopping summer dormancy may be necessary when a vigorous vegetative growth of grass i s desired to f i l l i n bare spots caused by damage from disease, play, and the careless use of t r a c t o r s , mowers and other implements. The practice of overwatering t u r f beyond moisture requirement during the summer, though probably not in t e n t i o n a l , prevents or curbs summer dormancy by keeping the s o i l temperature low. Although the l i m i t i n g of the dormancy may be necessary at times as mentioned above, t h i s widespread practice probably more often causes harm than good. Prevention of summer dormancy prevents the accumulation of reserves and thus weakens the t u r f . Excessive watering also causes increased loss of soluble s o i l nutrients through leaching; physical s o i l proper-t i e s may deteriorate as a re s u l t of overwatering (e.g. compac-t i o n ) . Thus, even when the l i m i t i n g of dormancy i s necessary, the manipulation of l i g h t intensity or photoperiod i s a better method than excessive watering to achieve t h i s goal. Ths cost of l i g h t control, of course, may prohibit i t s widespread use, though i t may be too early to worry about the economy when the actual technique of such l i g h t control has yet to be worked out. 113 V. SUMMARY AND CONCLUSIONS An instrument was constructed to obtain t u r f cores with a minimum of disturbance f o r the quantitative estimation of reserves. Sod reserve index i s defined ( i n sensu Burton and Jackson, 1 9 6 2 ) as the oven dry weight (in mgs.) of eti o l a t e d grass produced by a unit area of cored t u r f . The production of e t i o l a t e d grass, and hence the sod reserve index, was found to be also influenced, to some degree, by several factors other than the actual reserve content: a. Variations due to the genotype of species and v a r i e t i e s . b. The length of time necessary for the exhaustion of reserves varies with species and v a r i e t i e s . c. Certain temporary conditions, such as summer dormancy may l i m i t the optimum expression of reserves as sod reserve index. d. Inadequate environmental control i n the dark chamber may reduce the r e l i a b i l i t y of the index. e. Improper cl i p p i n g height and frequency may depress the productivity of cores (the imposed leve l s of cl i p p i n g height and frequency treatments do not 1 1 9 produce a convincing proof that would support this statement.) The method used proved to be sensitive enough to reveal sod reserve index differences related by: a. Variations i n the duration and i n t e n s i t y of l i g h t , • b. Variations in management and s o i l . c. Variations i n the extent of wear and compaction. d. Genetical differences. e. Seasonal v a r i a t i o n s . 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B u l l . 391. 1936 b Hydration studies i n fresh and dried red clover roots and shoots with reference to physical properties and chemical compo-s i t i o n of tissue. Plant Physiol. 11: 873-380. Greenhill, W.L. I960 Determination of dry weight of herbage by drying method. J. B r i t . Grassland Soc. 15: 48-54. Harper, K.H., and P h i l l i p s , T.G. 1943 The composition of timothy, part I I . Storage organs. N.H. Agr. Exp. Sta. Tech. B u l l . 81. Harrison, CM. 1931 Effect of cutting and f e r t i l i z e r a p p l i -cations on grass development. Plant Physiol. 6: 669-684. 1934 Responses of Kentucky bluegrass to variations i n temperature, l i g h t , cutting and f e r t i l i z i n g . Plant Physiol. 9: 83-106. Heinze, P.H., and Murneek, A.E. 1940 Comparative accuracy and e f f i c i e n c y in determination of carbohydrates i n plant material. Mo. Agr. Exp. Sta. Res. B u l l . 314. Janse, J.M. 1925 Ernahrung, Adventivbildung und P o l a r i t a t . Flora; order- Algem. Bot. 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Lamba, P.S., Ahlgren, H.L., and Muckenhirn, R.J. 1949 Root growth of a l f a l f a , medium red clover, bromegrass, and timothy under various s o i l conditions. Agron. J. 41: 451-458. Lan^ley, B.C., and Fisher, C.E. 1939 Some effects of contour l i s t i n g on native grass pastures. J. Am. Soc. Agron. 31: 972-981. Leukel, V/.A, 1929 Leukel, W.A. 1930 Deposition and u t i l i z a t i o n of reserve foods i n a l f a l f a plants. J. Am. Soc. Agron. 19: 596-623. and Coleman, J.K. Growth behaviour and maintenance of organic foods i n bahiagrass. F l a . Agr. Exp. Sta. B u l l . 219. L e v i t t , J., and Siminovitch, D. 1940 Loeb, J, 1924 Loomis, W.E. 1932 Lovvorn, R.L. 1945 The relationship between f r o s t resistance and the physical state of protoplams. I. The protoplasm as a whole. Can. J. Res. C. 18: 550-561. Theory of regeneration based on mass action. J . Gen. Physiol. 6: 207-214. Growth d i f f e r e n t i a t i o n balance vs. carbohydrate-nitrogen r a t i o . Proc. Am. Soc. Hort. S c i . 29: 240-245. The effect of d e f o l i a t i o n , s o i l f e r t i l i t y , temperature, and length of day on the growth of some perennial grasses. J. Am. Soc. Agron. 37: 570-582. 123 McCarty,, E.C. I935 Seasonal march of carbohydrates in Elymus ambiguus and Muhlenbergia  g r a c i l i s , and t h e i r reaction under moderate grazing use. Plant Physiol. 10: 727-73$. 193$ The r e l a t i o n of growth to the varying carbohydrate content i n mountain brome. U.S. Dep. Agr. Tech. B u l l . 59$. McCarty, E.C, and Price, R. 1942 Growth and carbohydrate content of important mountain forage plants i n central Utah as affected by clip p i n g and grazing. U.S. Dep. Agr. Tech. B u l l . 1$. Mcllvanie, S.K. 1942 Carbohydrate and nitrogen trends i n bluebunch wheatgrass, Agropyron spicatum, with special reference to grazing i n -fluences. Plant Physiol. 17: 540-547. Madison, J.H. I960 The mowing of turfgrass. I. The effect of season, i n t e r v a l , and height of mowing on the growth of seaside bentgrass t u r f . Agron. J. 52: 449-452. 1962 a. The effect of management practices on invasion of lawn t u r f by Bermuda-grass (Cynodon dactylon L.) Proc. Am. Soc. Hort. S c i . $0: 559-564. 1962 b. Mowing of turfgrass. II. Responses of three species of grass. Agron. J . 54: 250-252. 1962 c. Mowing of turfgrass. III. The effect of rest on seaside bentgrass t u r f mowed d a i l y . Agron. J . 54: 252-253. 1962 d. Turfgrass ecology. Effects of mowing, i r r i g a t i o n , and nitrogen treatments of Agrostis p a l u s t r i s Huds. "Seaside" and Agrostis tenuis Sibth. "Highland" on population, y i e l d , rooting, and cover. Agron. J . 54: 407-412. 129 Madison, J.H., and Hagan, R.M. 1962 Extraction of s o i l moisture by Merion bluegrass tur f as affected by i r r i g a t i o n frequency, mowing height, and other c u l t u r a l operations. Agron. J. 54: 157-160. 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Exp. Sta. B u l l . 535. Spoehr, H.A. 1919 The carbohydrate economy of c a c t i . Carnegie Inst. Wash. Publ. 28*7. 132 Sprague, H.B, 1933 Sprague, V.G. Root development of perennial grasses and i t s r e l a t i o n to s o i l conditions. S o i l S c i . 36: 189-209. The effects of temperature and daylength on seedling emergence and early growth of several pasture species. S o i l S c i . Soc. Am. Proc. 8: 287-294. Sprague, V.G., Calson, G.E., Motter, G.A. 1962 Regrowth of grasses i n darkness i n d i -cates r e l a t i v e energy accumulation. Paper presented at I962 Ann. Meeting of Am. Soc. Agron. Div. VII. Sprague, V.G., and Sulli v a n , J.T. 1950 Reserve carbohydrates i n orchardgrass clioped p e r i o d i c a l l y . Plant Physiol. 25: 92-102. Stapledon, R.G., and Milton, W.E.J. 1930 The ef f e c t of di f f e r e n t cutting and manurial treatments on the t i l l e r and root development of cocksfoot. Welsh J. Agr. 6: 166-174. Steel, R.G.D., and Torrie, J.H. I960 Stuckey, I.H, 1941 Sturkie, D.G. 1930 Sull i v a n , E.F. 1962 Sullivan, J.T. 1951 Pr i n c i p l e s and procedures of s t a t i s t i c s , McGraw-Hill, I960, pp. 480. Seasonal growth of grass roots, Am. J . Bot. 28: 486-491. The influence of various top-cutting treatments on root stocks of Johnson grass(Sorghum halepense). J. Am. Soc. Agron. 22: 82-93. Effect of s o i l reaction, c l i p p i n g height, and nitrogen f e r t i l i z a t i o n on the produc-t i v i t y of Kentucky bluegrass sod trans-plants i n pot culture. Agron. J . 54: 261-263. Guide to carbohydrate analyses of forage plants. U.S. Reg. Pasture Res. Lab. Mimeo. 133 S u l l i v a n , J . T . , and Sprague, V . G . I943 Composit ion of the r o o t s and s t u b b l e of p e r e n n i a l ryegrass f o l l o w i n g p a r t i a l de-f o l i a t i o n . 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Watkins, J.M. 1940 The growth habits and chemical compo-s i t i o n of bromegrass, Bromus inermis Leyss., as affected by di f f e r e n t environ-mental conditions. J . Am. Soc. Agron. 32: 527-53$. Weaver, J.E. 1919 The ecological relations of roots. Carnegie Inst. Publ. 2$6. Weaver, J.E., and Zink, E. 1946 Length of l i f e of roots of ten species of perennial range and pasture grasses. Flant Physiol. 21: 201-217. Weinmann, H. 1940 Seasonal changes in the roots of some South African highveld grasses. J. S. Afr. Bot. 6: 131-145. 1947 a. Investigations on the underground re-serves of South African grasses. DSc. Thesis, U. Wits., Johannesburg. 1947 b. Determination of t o t a l available carbo-hydrates i n plants. Plant Physiol. 22: 279-290. 194$ Underground development and reserves of grasses. A review. J. B r i t . Grassland Soc. 3: 115-140. 135 Weinmann, H.^and Reinhold, L. 1946 Reserve carbohydrates i n South African grasses. J. S. Afr. Bot. 12: 57-73. Willard, C.J., and McClure, G . M . 1932 The quantitative development of tops and roots in bluegrass with an improved method of obtaining root y i e l d s . J. Am. Soc. Agron. 24: 509-514. 136 APPENDIX 137 Appendix A Experiment No. 1. Sod reserve indexes of lawn cores from 4 locations, grown in darkness for 20 days. Location Replication "A" "B" "C" "D" a 60 61 130 141 b 44 102 160 288 t o t a l 104 163 290 429 x 52 SI.5 145 214.5 C V . 21.7$ 35.5% 14.6% 48.5% Appendix B Experiment No. 2. Sod reserve indexes of 8 lawn cores f o r 30 days. Replication a 205 b 225 c 205 d 251 e 188 f 220 g 184 h 192 t o t a l 1670 X 208 C V . 10.8 Appendix C Experiment No. 3. Sod reserve indexes of cores of a bluegrass-fescue lawn, sampled on June 28. and harvested twice, on July 6, and 16, 19o2. Treatments: 1, 2, 3, and 4 inches of core depth. Rep l i c a t i o n Treatments 1" 2" 3" 4 " July 6 July 16 Total July 6 July 16 Total July 6 July 16 Total July 6 July 16 Total a 27 81 108 13 208 221 20 290 310 40 299 339 b 154 158 312 34 308 342 80 240 320 40 181 221 c 13 317 330 36 60 96 38 120 156 40 129 169 d 27 40 67 11 157 168 28 118 146 24 89 113 e 111 288 399 136 469 605 115 481 596 90 349 439 f 95 262 357 87 252 339 42 555 597 104 414 518 g 77 428 505 87 420 507 63 328 391 112 371 483 h 108 450 558 85 431 516 117 609 726 102 420 522 T o t a l 2636 2794 3242 2804 Analy s i s of Variance Source of d. f . c 5. S. K. S. F v a r i a t i o n T o t a l 31 973,561 CV. = 51. 3% Treatments 3 25,382 8,460 n.s. Error 28 949,614 33,914 Appendix D Experiment No. 4. Sod reserve indexes of cores of a bluegrass lawn, sampled on August 18, and harvested on August 28, September 7, and 17, 1962. Treatments: 1, 2, and 3 inches of core depth. Replication Treatments 1" 2" 3" Harvest dates Harvest dates Harvest dates Aug.28 Sept.7 Sept.17 Total Aug.28 Sept.7 Sept.17 Total Aug.28 Sept.7 Sept.17 Total a 128 25 15 168 110 15 _ 125 55 29 8 92 b 133 60 40 233 107 10 4 121 121 30 21 172 c 74 59 17 150 155 33 32 220 164 37 25 226 d 97 16 4 117 152 20 — 172 51 21 22 94 e 119 52 25 196 106 50 20 176 119 28 8 155 f 121 32 25 178 108 31 11 140 201 12 8 221 g 51 13 4 68 141 12 4 157 117 29 22 168 h 26 41 21 88 112 69 28 209 221 56 35 312 Totals 1198 1320 1440 Analysis of Variance d. f . S. S. M. S. Source of  v a r i a t i o n T o t a l 23 71,980 C V . = 34.6% Treatment 2 3,660 1,830 n.s. Error 21 68,320 3^253 Appendix E Experiment No. 5. Sod reserve indexes of lawn cores sampled September 9, and grown i n dark for 20 days. 10 f e r t i l i z e r treatments. Replication Treatments Total 1 2 3 4 5 6 7 8 9 10 a 45 31 27 55 52 55 75 89 115 56 600 b 99 53 33 45 39 104 46 72 36 45 572 c 13 69 33 70 51 43 79 76 45 74 553 Total 157 153 93 170 142 202 200 237 196 175 1725 52.3 51.0 31.0 56.6 47.3 67.3 66.6 79.0 65.3 58.3 57.5 Analysis of Variance I. Analysis of Variance I I . (10 F e r t i l i z e r treatments) (Two ra d i a t i o n l e v e l s ) Source of d. f . S. S. M . S. F Source of d. f. S. S. Ni. S. F v a r i a t i o n v a r i a t i o n Total 29 12,758 Total 29 12,758 Treatment 9 4,741 526 1.31 Treatment 1 2,901 2.901 8.24 (n.s. ) Error 20 8,017 400. 8 Error 28 9,857 352 C . V. = 34.7$ C. V. = 32.6$ r-> o Appendix F Experiment No. 6(A). Sod reserve indexes of cores sampled on 5 dates at McCleery Golf Course. Coring Harvest Fairwa y Practice green Green No. 11 Green No. 18 dates dates cores Total cores Total cores Total cores Total a b c • a b c a b c a b c Oct. Nov. 6 166 207 123 262 201 263 280 175 260 251 227 208 27 16 27 17 9 134 117 105 107 65 161 132 156 51 1962 26 _ — — 27 40 33 9 5 14 1076 18 26 7 1076 Total 193 224 132 549 423 353 401 1182 396 245 435 401 409 266 Dec.17 287 422 246 207 224 230 185 186 210 181 289 350 Dec. 27 106 182 160 258 249 182 48 35 117 126 199 113 7. Jan. 7 19 34 20 167 89 72 - - 20 58 56 31 T o t a l 412 638 426 1476 632 562 484 1678 233 221 347 801 365 544 494 1403 Feb. Feb.22 211 232 282 263 240 259 275 334 323 300 319 279 12, Mar. 4 41 19 73 52 75 52 77 67 66 73 70 1963 14 - - - 12 40 26 49 81 19 39 33 26 Total 252 251 334 837 343 332 360 1040 376 492 409 1277 405 425 375 1205 Mar. 9 319 272 263 228 223 378 221 256 231 225 130 180 Feb. 19 78 5*. 37 102 148 146 189 147 160 139 77 122 27. 29 — — - 23 42 31 43 24 24 26 36 20 Apr. 8 - - - - 12 11 11 - 10 - — -Total 397 330 350 1077 353 425 566 1344 464 427 425 1316 390 243 322 955 Mar.24 415 491 367 260 313 266 226 283 296 289 344 382 Mar. Apr. 3 138 85 165 80 94 108 77 63 79 77 70 97 14. 13 52 32 76 14 29 21 14 12 17 19 14 9 23 - - - 11 10 9 - - 7 - - 11 Total 605 608 608 1821 365 446 404 1215 317 358 399 1074 335 428 499 1312 Season Tot a l 1359 2051 1350 5760 2121 2123 2215 6459 1736 1743 2015 5544 1946 2049 1956 5951 TOTAL 3,883 5,358 4,359 4,692 5,422 142 Appendix F (Cont.) Analysis of Variance Source of d f s s # M > s > p v a r i a t i o n Total 59 723,205 Sampling dates 4 144,077 36,019 3.42 * Error 55 579,128 10,529 S d » 41.89 S~ - 29.62 C. V.= 25.9 The least s i g n i f i c a n t ranges calculated for Duncan's multiple-range test for the 0.05 and 0.01 proba-b i l i t y l e v e l s were the following: Probability Value of p 2 3 4 5 0 # 0 5 SSR 2.837 2.987 3.085 3.147 LSR 84.0 88.4 91.3 93.2 SSR 3.775 3.935 4.045 4.133 0.01 LSR 111.8 116.5 H9.8 122.4 Appendix G Experiment No. 6(B). Sod reserve indexes of cores sampled on 5 dates at Point Grey Golf and Country Club. Coring Harvest Green No . 3 Green No. 14 Green No . 15 dates dates cores cores cores T O T 4 1 a b c Total a b c Total a b c Total 1 U i H i Nov. Nov.12 266 224 139 110 115 132 94 169 134 2, " 22 61 85 42 23 31 42 22 25 17 1962 Dec. 3 15 12 14 - - 24 - - -Total 342 321 195 858 133 146 198 477 116 194 151 461 1796 Dec. Dec.17 140 115 155 106 217 148 174 114 245 7. " • 27 116 100 154 136 122 129 87 69 139 Jan. 7. 23 41 88 41 15 42 34 55 17 Total 279 256 397 932 283 354 319 956 295 238 401 934 2822 Feb. Feb.22 237 127 167 77 126 191 198 142 I83 12, Mar. 4 53 48 13 15 29 36 28 30 68 1963 " 14 38 52 - 11 19 - - - 49 Total 328 227 180 735 103 168 227 498 226 172 300 698 1931 Mar. 9 95 68 82 137 114 52 81 122 144 Feb. " 19 28 25 58 154 49 23 29 48 46 27. " 29 - - - - - - - - -Apr* 8 - - - - - • - - - -Total 123 93 140 356 291 163 75 529 110 170 190 470 1355 Mar.24 160 131 135 183 193 174 155 140 159 Mar. Apr. 3 — 21 30 - 26 - 32 29 50 14. " 13 " 23 - - - 28 — 19 — — — Total 160 152 165 477 211 219 193 623 187 169 209 565 166 5 Season t o t a l 1232 1049 1077 3358 1021 1050 1012 3083 934 943 1251 3128 9569 144 Source of var i a t i o n Appendix G (Cont.) Analysis of Variance d. f . S. S. M. Total 44 285 ,719 Sampling date 4 134 ,796 33 ,699 8 . 4 6 *** Error 40 150,923 3 , 9 8 0 S d = 29 . 74 SJJ = 21 .03 C.V. = 2 9 . 6 % The least s i g n i f i c a n t ranges calculated with Duncan's multiple-range test f o r the 0 . 05 and 0 . 0 1 p r o b a b i l i t y levels were the following: Probability Value of p 2 3 4 5 SSR 2 . 8 6 3 . 0 1 3 . 1 0 3 . 1 7 0 .05 LSR 6 0 . 1 63 .3 65 .2 6 6 . 6 SSR 3 . 82 3 . 9 9 4 . 1 0 4 . 1 7 0 . 0 1 LSR 80 .3 8 3 . 9 8 6 . 2 8 7 . 7 Appendix H Experiment No. 6(C). Sod reserve indexes of cores sampled on 5 dates at Shaughnessy Golf and Country Club. Coring Harvest Green No. 12 Green No. 14 Green No. 15 dates dates cores cores cores a b c Total a b c Total a b c Total Nov. Nov.20 220 229 206 218 265 174 270 228 189 10. " 30 207 160 93 154 176 104 326 258 307 1965 Dec.10 31 40 14 45 34 25 85 90 106 Total 45$ 429 313 1200 417 475 303 1195 681 576 602 1359 Dec. Dec.17 113 198 107 69 102 110 208 163 148 7. " 27 221 208 168 143 116 189 243 231 206 Jan. 7 175 96 136 149 180 161 159 190 265 Total 514 502 411 1427 316 398 460 1174 610 534 619 1813 Feb. Feb.22 225 199 211 194 221 177 148 249 203 12, Mar. 4 89 125 112 116 126 137 215 231 194 1965 " 14 112 121 103 145 50 54 169 174 59 Total 426 445 426 1297 455 397 368 1220 532 654 461 1647 Mar. 9 125 81 95 129 — 130 72 149 94 Feb. " 19 161 200 218 - 163 145 263 344 281 27. " 29 58 51 55 39 45 39 108 90 83 Apr. 8 - 17 15 - 9 - 39 22 34 Total 344 349 383 1076 168 217 314 699 482 605 492 1579 Mar.24 198 168 230 300 246 157 170 311 325 Mar. Apr. 3 134 99 84 97 186 122 210 178 103 14. ti 13 8 10 19 7 30 19 18 37 31 » 23 - - - 6 9 9 17 21 -Total 340 277 333 950 410 471 307 1188 415 547 459 1421 Season t o t a l 2082 2002 1866 5950 1766 1958 1752 5476 2720 2966 2633 3319 TOTAL 4,254 4,414 4,164 •p-3,354 3,559 146 Appendix H (Cont.) Analysis of Variance Source of va r i a t i o n d. f . 3 • S • M. S. F Total 583,636 Sampling date 4 95,733 23,933 1.96 n.s. Error 487,903 12,197 S d = 52.06 S x = 36.81 c . v . = 25.1 fo The least s i g n i f i c a n t ranges calculated with Duncan's multiple-range test for the 0.05 p r o b a b i l i t y l e v e l were the following: Value of p 2 3 4 5 SSR 2.86 3.01 3.10 3.17 LSR 105.2 110.7 114.1 116.6 Appendix I Experiment No. 6( on 5 Coring Harvest Green No. dates dates a cores b Nov. Nov.24 122 91 Dec. 4 22 45 1962 " 14 - -Total 144 136 Dec. Dec.17 132 53 7. " 27 37 52 Jan. 7 9 10 Total 178 115 Feb. Feb.22 53 25 1963 Mar. 4 6 5 " 14 - -Total 64 30 Mar. 9 102 125 Feb. " 19 56 76 27. " 29 13 24 Apr. 8 - -Total 171 225 Mar.24 211 155 Mar. Apr. 3 46 36 14. " 13 11 8 " 23 6 -Total 274 199 Season t o t a l 831 705 ). Sod reserve indexes of co ates at University Golf Club. 6 Green No. 8 cores c Total a b c Total 174 270 221 264 60 147 79 89-- 48 42 -234 514 465 342 353 1160 191 131 222 139 25 96 155 133 7 71 61 38 223 516 298 438 310 IO46 34 150 103 73 6 21 27 10 - - 49 -40 134 171 179 83 433 74 104 67 92 76 31 17 35 150 546 135 84 127 346 132 190 133 202 29 57 29 34 - 16 - -161 634 263 162 236 661 808 2344 1332 1205 1109 3646 s sampled Green No, . 11 cores TOTAL a b c To t a l 117 79 137 25 41 27 - 27 15 142 147 179 463 2142 126 79 124 63 74 56 35 26 25 229 179 205 613 2175 105 136 62 26 40 14 18 26 41 149 202 117 468 1035 116 155 72 83 59 18 10 12 -209 226 90 525 1417 144 133 202 33 39 177 133 241 551 1846 906 387 832 2625 8615 148 Appendix I (Cont.) Analysis of Variance Source of va r i a t i o n Total Sampling dates Error C V . d. f . 44 4 40 38.31 27.1 40.7 % S. S. H. S. 371,100 106,886 26,721 264,214 6,605 4.04 ** The least s i g n i f i c a n t ranges calculated with Duncan's multiple-range test f o r the 0.05 and 0.01 prob a b i l i t y l e v e l s were the following: Probability Value of p 2 3 4 5 SSR 2.86 3 .01 3.10 3.17 LSR 77.5 81.5 84.0 85.9 SSR 3.82 3.99 4 .10 4.17 LSR 103.5 108.1 111.1 113.0 0.05 0.01 149 Appendix J Experiment No. 7. Sod reserve indexes of 4 species and 4 core-lengthsy, cored on May 7, 1963. Harvest dates Harvest dates Bent May17 May27 June6 Total Bluegrass Mayl7 May27 June6 Total 4" a 140 35 9 184 4" a 261 62 11 334 b 104 21 6 131 b 184 70 15 269 c 128 16 8 152 c 218 33 29 330 d 104 44 - 143 d 232 40 - 272 e 142 35 13 190 e 194 70 20 284 f 131 46 8 135 f 210 66 14 290 Total 749 197 44 990 Total 1299 391 89 1779 2" a 119 50 7 176 2" a 195 106 21 322 b 133 14 10 157 b 203 24 10 237 c 250 71 27 343 c 241 86 - 327 d 109 25 11 145 d 170 21 - 191 e 138 31 16 185 e 169 39 — 203 f 152 54 13 224 f 201 86 5 292 Total 901 245 39 1235 Total 1179 362 36 1577 1" a 124 49 16 189 1" a 137 78 27 242 b 78 20 20 118 b 109 47 - 156 c 83 30 14 127 c 163 56 19 238 d 97 30 19 146 d 136 45 8 139 e 150 49 32 231 e 211 72 mm 283 f 117 15 16 148 f 140 45 7 192 Total 649 193 117 959 Total 896 343 61 1300 86 18 8 112 a 133 _ 19 152 b 74 17 5 96 b 153 78 14 245 c 118 20 13 151 c 164 55 75 294 d 139 20 - 159 d 125 - - 125 e 112 28 - 140 e 142 - - 142 f 78 11 6 95 f 73 - - 73 Total 607 114 32 753 Total 790 133 108 1031 150 Appendix J . (Continued). Harvest dates Harvest dates Fescue May17 May27 June6 Total Ryegrass Mayl7 May27 June6 Tot 4" a 163 23 4 190 4" a 33 b 135 16 - 151 b 29 c 131 7 - 138 c 28 d 76 6 5 37 d 63 e 107 14 - 121 e 34 f 93 14 3 115 f 49 Total 710 80 12 802 Total 241 2" a 119 15 12 146 2" a 27 b 178 70 - 2^3 b 40 c 105 17 14 126 c 53 d 86 12 _ 93 d 26 e 129 32 4 165 e 36 f 162 19 5 186 f 64 Total 779 165 25 969 Total 246 1" a 101 32 3 136 1" a 74 b 103 - 6 109 b 69 c 92 25 6 123 c 37 d 80 22 4 106 d -e 73 14 - 87 e -f 110 26 4 140 f 30 Total 559 119 23 701 Total 210 a 97 _ 97 s" a 51 b 81 11 3 95 b 48 c 93 — 93 c 77 d 62 - - 62 d 16 e 45 10 • - 55 e 22 f 39 - - 89 f 71 Total 467 21 , 3 491 Total 235 2 151 Appendix J . (Cont.) Analysis of Variance Source of var i a t i o n Total Treatments A. Species B. Core length A x B Error d. f. S. S. M. S. F 71 333,730 (11) (251,446) (22,853) (10.37 **) 2 158,769 79,334 36.01 3 76,505 25,501 11.57 6 16,172 2,695 1.22 n.s. 60 132,284 2,204 s x CV. 27.10 19.16 26.8 % P r o b a b i l i t y 0.05 0.01 Least S i g n i f i c a n t Ranges 2 3 4 SSR 2.83 2.98 3.08 LSR 54.2 57.1 59.0 SSR 3.76 3.92 4.03 LSR 7 2 . 0 75.1 77.2 A p p e n d i x K E x p e r i m e n t N o . 8. S o d r e s e r v e i n d e x e s o f M e r i o n K e n t u c k y b l u e g r a s s c o r e s , c o r e d on J u l y 2. T r e a t m e n t s : 4 c l i p p i n g f r e q u e n c i e s , 2 c l i p p i n g h e i g h t s . C l i p p i n g f r e q u e n c i e s o v e r a 6 v /eeks p e r i o d 6 t i m e s 3 t i m e s t w i c e o n c e J u l y J u l y J u l y J u l y A u g . A u g . T o t a l J u l y J u l y A u g . T o t a l J u l y A u g . T o t a l A u g . 9 16 23 30 6 13 16 30 13 23 13 13 407 503 . . . _.- .. , . 573 1/2" d 190 121 78 97 29 49 564 321 176 89 586 411 174 585 649 466 405 3003 a 53 86 62 59 52 215* 527 145 134 240* 519 160 339* 499 K s n sri s o 99 9"\ 21Q 1.0 m ii.A K9f\ m 9&Q i.9? CO c G +3 0 1 - 1 jC •H Pu bO +3 CL.-H CO • H 0J O rH x: • H 0 rH O a 206 191 118 95 43 37 690 287 102 151 540 400 139 539 b 188 128 99 54 32 16 517 314 152 46 512 239 106 395 c 190 139 102 85 34 26 576 253 161 47 46I 405 159 564  0 1     4 1  6 1 4  e 207 140 139 95 33 . 21 635 272 152 55 479 374 183 557 f 235 153 99 61 38 27 613 411 178 109 698 298 211 509 T o t a l 1216 872 635 437 209 176 3595 1853 921 497 3276 2177 972 3149 a 53 86 62 59 52 215* 527 145 134 240* 519 160 339* 499 b 0 58 59 22 23 39 451 9 31 3 6 26 53 26  422 c 31 47 50 30 45 243 446 114 110 274 498 141 288 429 d 46 70 54 38 18 70 496 122 106 271 499 150 323 473e 93 30 100 53 27 221 574 120 97 139 406 299 376 675 f 52 60 86 21 24 210 453 118 103 266 487 172 274 446 T o t a l 325 401 411 223 189 1398 2947 668 681 1536 2935 1075 1869 2944 IV) * C l i p p i n g h e i g h t i s t h e s a m e , 1/2" f o r a l l c o r e s o n f i n a l h a r v e s t d a t e . 153 Appendix K (Cont.) 3d ' 40.39 = 28.55 C. V. = 13.3 Analysis of Variance I . (Fact o r i a l ) Source of v a r i a t i o n d. f. S. S. M. S. F Total 35 207.067 Treatments (5) (57.214) A. Clipping frequency 2 9.030 4.515 n.s. B. Clipping height 1 39.601 39.601 8.09 ** Interaction A x B 2 8.583 4.291 n.s. Error 30 146.853 4.895 Analysis of Variance II, (Non-factorial) Source of v a r i a t i o n Total Treatments Error d. f. 41 6 35 s. s. 253.156 59.935 193.221 = 42.89 = 30.33 C. V. - 14.2 % Sx Value of p SSR LSR Least S i g n i f i c a n t Ranges 2 3 4 5 2.87 3.02 3.11 3.18 87.2 91.7 94.3 96.6 M. S. 6 3.23 98.1 9.989 1.80 n.s, 5.520 7 3.28 99.4 154 Appendix L Experiment No. 9. Oven-dry weight of grass produced i n f i e l d with and without l i g h t from June 25 to July 25, 1963, Species Highland bent Perennial rye Treatment control dark control dark gms./sq. f t , 2.62 4.27 5.75 • Appendix M Experiment No. 10. Oven-dry weight ( i n gms./sq. f t . ) of bluegrass produced i n f i e l d with and without l i g h t with two c l i p p i n g frequencies between July 27 and August 16, 1963 Light R e p l i -t r e a t - cation ment control dark Harvested once August 16 Clipping treatment Harvested twice August 6 August 16 t o t a l of 2 a 9.43 3.06 4.46 7.52 b 8.81 3.01 6.31 9.32 18.24 6.07 10.77 16.84 a 3.00 3.45 4,. 55 8.00 b 8.30 , 3.90 4.93 3.83 16.80 7.35 9.48 16.83 Appendix N Monthly Means June July Aug. Temperature Mean max. 6 4 . 4 67.7 66.3 Mean min. 51.3 55.6 55.5 Mean av. 58.1 61.7 60.9 Earth temp.A.M47.53 64.43 62.18 means at 411 P .M. 54 .92 76.10 69.73 Hours of Sunshine 287.9 290.2 178.6 Rain (in.) .84 .98 4.29 Snow (in.) Sums of Basic Meteorological Data University of B.C. Weather Station from June 1962 through August 1963 Sept. Oct. Nov. Dec. Jan. Feb. 64.O 56.4 49.1 45.1 37.1 50.4 52.7 48.1 41.6 37.5 29.0 40.5 58.3 52.2 45.3 41.3 33.0 45.4 58.12 51.26 44.97 40.75 33.90 40.87 66.04 55.04 47.12 42.21 34.86 44.33 205.5 101.2 47.1 45.7 84.9 73 o0 2.65 4 .91 8.34 9.11 .72 5.87 3.00 .25 2.15 ecorded at the Mar. Apr. May June July Aug. 48.1 53.0 63 .0 64.6 66 .5 70.1 38.0 42.8 47.9 52.8 55.0 57.4 43. c 47.9 55.4 58.7 60.7 63.7 41.05 47.02 55.85 61.85 62.50 62 .20 46.86 54.46 67.78 72.04 71.74 74.89 120.8 128.0 326.7 207.8 224.0 257.8 3.36 2.91 1.49 1.62 3.10 .68 v n 156 Appendix N. (Cont.) Grass Minimum Temperatures (F) at the University of B.C. Weather Station from November 16, 1962 through A p r i l 15, 1963 Date Nov. Dec. Jan. Feb. Mar. Apr 0 1 30 44 20 31 30 2 32 43 27 32 32 3 30 37 39 27 35 4 36 34 43 28 42 5 40 30 42 26 43 6 37 29 45 27 41 7 44 36 36 28 37 8 46 36 33 30 41 9 30 32 35 31 42 10 31 11 34 30 . 34 11 38 10 31 36 39 12 30 12 32 27 46 13 40 17 32 35 37 14 46 27 42 37 43 15 37 32 32 33 41 16 33 44 28 42 37 17 37 42 33 43 31 18 36 41 23 40 35 19 42 38 20 44 38 20 43 41 23 41 42 21 33 41 24 35 44 22 33 27 31 32 32 23 35 26 25 38 37 24 39 23 27 39 31 25 37 23 25 36 41 26 38 22 21 44 40 27 36 30 22 35 43 28 30 33 18 38 41 29 34 39 11 35 30 32 42 14 34 31 39 19 32 

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