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Floral initiation in Bromus species and the effect of planting time on seed production of Bromus inermis… Clarke, John Mills 1973

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V0' FLORAL INITIATION IN Bromus SPECIES AND THE EFFECT OF PLANTING TIME ON SEED PRODUCTION OF Bromus inermis CLIMATYPES AT BEAVERLODGE, ALBERTA by JOHN MILLS CLARKE B.Sc. ( A g r . ) , U n i v e r s i t y of B r i t i s h Columbia A Thesis Submitted in P a r t i a l F u l f i l m e n t of the Requirements f o r the Degree of Master of Science in the Department o f P l a n t Science We accept t h i s t h e s i s as conforming t o the req u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 19 75 In presenting 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 permission 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 r e p r e s e n t a t i v e s . 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 permission. Department The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada i ABSTRACT The times of f l o r a l i n i t i a t i o n of Bromus inermis v a r i e t i e s C a r l t o n (northern-type) and Redpatch (southern-type) and B. pumpellianus from three l a t i t u d e s were determined under f i e l d c o n d i t i o n s a t Beaverlodge, A l b e r t a . This was done by re c o r d i n g developmental stage of a p i c a l meristems of t i l l e r s during the s p r i n g and f a l l . A dates of seeding t r i a l i n v o l v i n g C a r l t o n and Redpatch was a l s o undertaken. I t was found t h a t both types of B. inermis underwent f l o r a l i n i t i a t i o n in the s p r i n g a t Beaverlodge. Both types s t a r t e d development a f t e r A p r i l 26 of 1971 and 1972. I t was concluded t h a t temperature was the major f a c t o r governing the onset of f l o r a l development in B. inermis. The B. pumpellianus accessions a l l underwent f l o r a l i n i t i a t i o n in the f a l l , p r i o r t o s o i l freeze-up. P o l a r bromegrass, which has both B. inermis and B. pumpellianus a n c e s t r y , behaved in a s i m i l a r manner. There were small d i f f e r e n c e s in the times a t which f l o r a l development s t a r t e d . I t i s probable t h a t day length i s the prime f a c t o r governing f l o r a l i n i t i a -t i o n of B. pumpellianus and P o l a r bromegrass in the f a l l . On the b a s i s of one year's seed y i e l d data, i t was suggested t h a t C a r l t o n and Redpatch should be seeded a f t e r mid-May but before mid-July when grown as seed crops a t Beaverlodge. I t was a l s o found t h a t p l a n t s which produced seed in the year f o l l o w i n g seeding had developed more than one t i l l e r p r i o r t o freeze-up in the year of seeding. Larvae of Hylemya sp. were found t o be damaging t i l l e r bases and a p i c a l meristems of Bromus spp. The extent of the l a r v a l i n f e s t a t i o n v a r i e d s e a s o n a l l y and y e a r l y . i i TABLE OF CONTENTS Page ABSTRACT i TABLE OF CONTENTS i i LIST OF TABLES i i i LIST OF FIGURES i v ACKNOWLEDGMENTS v INTRODUCTION 1 LITERATURE REVIEW 3 I. Genecology 3 II. Genetic D r i f t 6 III. Environmental Physiology 7 a) External Environment 7 b) Internal Environment 11 IV. Apical Development 13 a) Ontogeny 13 b) Inflorescence Development - Rating Systems 13 V. Dates of Seeding 14 MATERIALS AND METHODS 15 I. Plant Material 15 II. Determination of Initiation Time 15 III. Dates of Seeding 17 IV. Insect Damage 17 RESULTS AND DISCUSSION 21 I. Initiation Times 21 II. Dates of Seeding 32 III. Insect Damage 38 SUMMARY 41 LITERATURE CITED 43 i i i LIST OF TABLES TABLE NO. Page 1. C i v f l daylength, d a i l y mean temperature and degree- ? 7 days above 38°F, A p r i l 1971 and 1972 a t Beaverlodge 2. C i v i l daylength (hours) a t Beaverlodge, Smithers, 29 Worsley and M i l e 1019 in September and October. 3. Dates of heading, a n t h e s i s and maturity of Bromus inermis and B. pumpellianus. 29 4. F a l l growth and subsequent seed y i e l d s of Redpatch 33 and C a r l t o n bromegrass seeded a t various dates in 1971. 5. F a l l growth of C a r l t o n and Redpatch bromegrass seeded 36 a t v a r i o u s dates in 1972. 6. May-October p r e c i p i t a t i o n 1971, 1972 and 45-year 36 average a t Beaverlodge. 7. Damage t o Bromus inermis and B. pumpellianus by 39 i n s e c t l a r v a e . iv LIST OF FIGURES Figure No. Page No. 1. Developmental stages of the bromegrass apex 18 2. R e l a t i o n s h i p between stage of apex development and c o l l e c t i o n date, s p r i n g 1971. 22 3. R e l a t i o n s h i p between stage of apex development and c o l l e c t i o n date, F a l l 1971 - Spring 1972. 23 4. R e l a t i o n s h i p between stage of apex development and c o l l e c t i o n date. F a l l 1972. 24 5. 1971 p r e c i p i t a t i o n and 1972 seed y i e l d of C a r l t o n and Redpatch bromegrass seeded a t v a r i o u s dates 34 in 1971. ACKNOWLEDGMENTS v The f i e l d work of the p r o j e c t was c a r r i e d out under the auspices of A g r i c u l t u r e Canada at the Research S t a t i o n , Beaverlodge, A l b e r t a . Laboratory f a c i l i t i e s and o f f i c e space were provided by the Department of P l a n t Science, U n i v e r s i t y of B r i t i s h Columbia and by A g r i c u l t u r e Canada. I am indebted t o Dr. C. R. E l l i o t t of the Research S t a t i o n , Beaverlodge f o r h i s u n t i r i n g a s s i s t a n c e in the planning of the study and in reviewing the manuscript. I a l s o wish t o thank Mr. Maurice H l l t z , • t e c h n i c i a n at the Research S t a t i o n , f o r h i s help in the maintenance of the p l a n t m a t e r i a l and in the c o l l e c t i o n of t i l l e r samples. Thanks are a l s o due t o Dr. V. C. B r i n k , P r o f e s s o r of Agronomy in the Department of P l a n t Science, U n i v e r s i t y of B r i t i s h Columbia, f o r h i s i n v a l u a b l e a s s i s t a n c e in the planning of the p r o j e c t and In prepara-t i o n of the manuscript. I g r a t e f u l l y acknowledge the a s s i s t a n c e of Dr. V. C. Runeckles and Dr. A. J . Renney, Chairman and P r o f e s s o r , r e s p e c t i v e l y , of the Department of P l a n t Science, Dr. L. A. Lowe of the Department of S o i l Science, and Dr. J . R. Maze of the Department of Botany f o r t h e i r a s s i s t a n c e . I am deeply indebted t o these people and many o t h e r s , I n c l u d i n g my w i f e , Frances, who c o n t r i b u t e d personal and t e c h n i c a l a s s i s t a n c e during the course of t h i s p r o j e c t . INTRODUCTION Smooth bromegrass (Bromus inermis Leyss.) i s an important forage grass in Western Canada and in O n t a r i o , where I t i s widely recommended in hay, s i l a g e and pasture mixtures. The "northern types" perform best in western areas, while the "southern-types" are b e t t e r s u i t e d t o O n t a r i o . Bromegrass seed i s produced in Western Canada. Seed y i e l d s of many of the "southern" s t r a i n s have been found t o be i n f e r i o r t o those of "northern" s t r a i n s . In 1971, Canada's production of bromegrass seed was 5,075,000 pounds, of which 3,000,000 pounds were produced in A l b e r t a . The inspected pedigreed seed acreage of bromegrass in Canada in 1971 included 6,525 acres of "northern t y p e " v a r i e t i e s and 2,701 acres of "southern-type" v a r i e t i e s , i n d i c a t i n g t h a t seed production of the "northern-types" i s c o n s i d e r a b l y more Important than t h a t of the southern-types. Exports of bromegrass during the period J u l y 1, 1971 t o June 30, 1972 amounted t o 1,041,416 pounds, most of which went t o the United States and l e s s e r amounts t o Western European c o u n t r i e s . Imports during the same period t o t a l e d 1,164,768 pounds, a l l of which came from the United S t a t e s . An expansion of the production of "southern-type" v a r i e t i e s in Canada would ensure an adequate supply of seed of these v a r i e t i e s t o meet domestic needs. I t could a l s o provide f o r an expansion of bromegrass seed exports t o the United S t a t e s , where "southern-type" v a r i e t i e s are widely used. The Peace R i v e r region of A l b e r t a and B r i t i s h Columbia i s one of Canada's major grass seed producing areas, and has a p o t e n t i a l t o expand i t s present l e v e l of p r o d u c t i o n . However, unless the low seed y i e l d s of "southern-type" bromegrass v a r i e t i e s are improved, there i s r e l u c t a n c e t o expand the present acreage of these v a r i e t i e s . 2 A f i e l d study a t Beaverlodge, A l b e r t a was undertaken t o study the i n i t i a t i o n times of C a r l t o n (northern-type) and Redpatch (southern-type) bromegrass, which are Canadian-bred v a r i e t i e s . A seeding dates t r i a l was a l s o conducted, and v e g e t a t i v e development and seed production of the two v a r i e t i e s were s t u d i e d . The o b j e c t i v e s of the study were t o determine i f the f l o r a l i n i t i a t i o n requirements of southern s t r a i n s were d i f f e r e n t from those of northern s t r a i n s , and i f the d i f f e r e n c e s , i f any, could be the cause of the lower seed y i e l d of the southern s t r a i n s . The responses of the two types t o seeding date were a l s o s t u d i e d . Development of northern areas has created a need f o r the e v a l u a t i o n of domestic and n a t i v e grass species f o r use in re - v e g e t a t i o n of p i p e l i n e , highway, r a i l w a y and powerline r i g h t s - o f - w a y , as well as f o r seeding a i r s t r i p s and i n d u s t r i a l s i t e s . E c o t y p i c races of n a t i v e grasses are known t o e x i s t , and are of importance in a s s e s s i n g the p o t e n t i a l of such s p e c i e s f o r domestication. Genecological s t u d i e s of the more promising species are re q u i r e d before p l a n t breeding programs can be undertaken. B. pumpellianus Scribn. i s n a t i v e t o northern Canada and Alaska and much of the western U.S.A. and i s taxonomicaI Iy and g e n e t i c a l l y s i m i l a r t o B. inermis. By s e l e c t i o n of s u i t a b l e p l a n t t y p e s , well adapted v a r i e t i e s or hybrids could be bred f o r use in northern areas. A f i e l d study was made a t Beaverlodge of the f l o r a l i n i t i a t i o n times of three B. pumpellianus accessions from three d i f f e r e n t l a t i t u d e s . The o b j e c t i v e of the study was t o determine whether f l o r a l i n i t i a t i o n time would vary with l a t i t u d e of o r i g i n . 3 LITERATURE REVIEW I. Genecology Olmstead (1943) reported geographic d i f f e r e n c e s w i t h i n the genus Bouteloua. He c o l l e c t e d f i v e s pecies from A r i z o n a , and one from Montana (13° of l a t i t u d e North of the other sampling s i t e s ) . P l a n t s of each species were exposed t o photoperiods of 16, 12 and 8 hours in a greenhouse t r i a l . The p l a n t s were found t o e x h i b i t s h o r t - and long-day c h a r a c t e r i s -t i c s . S t r a i n s from the northern sampling area tended t o show more long-day c h a r a c t e r i s t i c s . A broader study of t h i s phenomenon was made by Olmstead (1944), using twelve geographic s t r a i n s of Bouteloua curtipendula (Michx.) T o r r . The sampling s i t e s ranged from San Antonio, Texas t o Cannonball, North Dakota - a range of about 17° of l a t i t u d e . P l a n t s of each s t r a i n were exposed t o photoperiods of 9, 13, 16 and 20 hrs in the greenhouse. Southern s t r a i n s (from Texas and Arizona) responded as intermediate o r short day pl a n t s - f l o w e r i n g on 13 hr. days. The s t r a i n s from North Dakota flowered when the day length was g r e a t e r than 14 hours, i n d i c a t i n g t h a t they were long-day p l a n t s . The maximum natural day length i s about 15 hours in the South (Texas), 17 hours in the North (North Dakota). Olmstead a l s o found t h a t with i n c r e a s i n g l a t i t u d e of o r i g i n , internodal e l o n g a t i o n and height growth were i n c r e a s i n g l y surpressed by short photoperiods of 13 and 9 hours. A s i m i l a r study was made of Andropogan saoparius Michx. by Larsen (1947). Samples were taken from twelve p o i n t s from Texas (at 28° 15'N l a t i t u d e ) t o North Dakota ( a t 47° 10'N). P l a n t s from each p o i n t of o r i g i n were exposed to a r t i f i c i a l day lengths of 13, 14 and 15 hours in a green-house. There was no f l o w e r i n g under 13 hour days. Southern s t r a i n s (28-36°) flowered under 14 hour days, w h i l e northern s t r a i n s (39-47°) flowered 4 under 15 hour days. Larsen suggested t h a t the southern s t r a i n s were intermediate In photoperiod response, while the northern s t r a i n s were long-day p l a n t s . McMillan (1956) made a study of c l o n a l m a t e r i a l of f i v e grass species sampled throughout the s t a t e of Nebraska. Among these was Bouteloua gracilis (H.B.K.) Lag. ex Steud. The date of a n t h e s i s was found t o vary with geographical a r e a , being e a r l i e r in the West than in the East. There was a d i f f e r e n c e of 36 days between the e a r l i e s t and l a t e s t . McMillan proposed t h a t t h i s was due t o the length of the growing season - the growing season was s h o r t e r in the West due t o an e a r l i e r and longer dry season. As a r e s u l t of t h i s , n a t u r a l s e l e c t i o n had favoured genotypes which had more r a p i d s p r i n g growth and e a r l i e r seed s e t . McMillan (1967) made a s i m i l a r study of four grass species from a h a b i t a t g r a d i e n t from the Gulf of Mexico in Texas t o the mountains of New Mexico. E l e v a t i o n v a r i e d from s e a - l e v e l t o 2800 meters a t Ranton P a s s 3 New Mexico. The grasses were t r a n s p l a n t e d i n t o a uniform nursery at A u s t i n , Texas. A tendency f o r e a r l i e r f l o w e r i n g and m a t u r i t y in the p l a n t s from the i n l a n d , h i g h - e l e v a t i o n s i t e s was observed. This again was probably a r e s u l t o f the length of the growing season and i t s s e l e c t i v e i n f l u e n c e . L a t i t u d i n a l v a r i a t i o n in Agropyron traahyeaulian ( L i n k ) Malte has been demonstrated (unpublished data, Research S t a t i o n , Beaverlodge). Native p l a n t s were c o l l e c t e d from 53° N l a t i t u d e in A l b e r t a t o 68° N in the Northwest T e r r i t o r i e s and planted in a nursery at Beaverlodge (55° 15' N l a t . ) . P l a n t s c o l l e c t e d above 58° N and e s p e c i a l l y above 61° N matured seed more r a p i d l y a f t e r heading than d i d p l a n t s c o l l e c t e d below 58°. The pl a n t s c o l l e c t e d above 61° N produced much le s s seed than p l a n t s from 53-61° N. With Increasing l a t i t u d e of o r i g i n , t h e re was a decrease In p l a n t 5 height, a decrease in dry matter p r o d u c t i o n , and an increase in the number of leaves per p l a n t . Sonneveld (1966) found v a r i a t i o n in p l a n t s of Lolium perenne L. c o l l e c t e d from o l d permanent grasslands throughout the Netherlands. V a r i a -t i o n s in the p h o t o p e r i o d i c requirements f o r heading were found t o be r e l a t e d t o environmental f a c t o r s . P l a n t s c o l l e c t e d in areas where moisture was l i m i t i n g l a t e in the growing season had a s h o r t e r p h o t o p e r i o d i c r e q u i r e -ment f o r heading. P l a n t s from areas where grazing was g e n e r a l l y i n t e n s i v e e a r l y i n the growing season required a longer photoperiod f o r heading. Wexelsen (1966) c o l l e c t e d p l a n t s of f i f t e e n n a t i v e red c l o v e r populations (Trifolium pvatense L. var. spontaneum WiI Ik.) from e l e v a t i o n s of 200-960 meters above sea l e v e l in the Norwegian E a s t l a n d . When grown at V ollebekk, Norway, there were v a r i a t i o n s between populations in growth type, amount of t i l l e r i n g , t h i c k n e s s of stem, f l o w e r i n g time and hay y i e l d . At higher e l e v a t i o n s there was a tendency toward l i t t l e t i l l e r i n g , f i n e stems, e a r l y f l o w e r i n g , low hay y i e l d s and a creeping growth h a b i t . P o p u l a t i o n s from lower e l e v a t i o n s were more e r e c t , t i l l e r e d b e t t e r , had c o a r s e r stems, flowered l a t e r and had higher y i e l d s . There are a l s o examples of v a r i a t i o n w i t h i n c u l t i v a t e d grasses which can be r e l a t e d t o geographical o r i g i n . The ecotype concept i s of major importance in the production of c u l t i v a t e d crops. The two important c o n s i d e r a t i o n s are p l a n t i n t r o d u c t i o n and seed production. L a t i t u d i n a l ecotypes of many c u l t i v a t e d p l a n t s have been shown t o e x i s t , and the development of l a t i t u d i n a l ecotypes has been demonstrated. E x i s t i n g l a t i t u d i n a l ecotypes are of importance in s e l e c t i n g m a t e r i a l f o r p l a n t i n t r o d u c t i o n , w h i l e the development of such ecotypes i s a concern in the production of b a s i c seed o u t s i d e the area of a d a p t a t i o n . Broue and Kawanabe (1967) stud i e d p l a n t s of f i f t e e n Daotylis 6 glomerata L populations ranging from 34° N l a t i t u d e in Lebanon t o 65° N l a t i t u d e in Norway. The p l a n t s were placed under a 16 hour day in a greenhouse. I t was observed t h a t the time of i n i t i a t i o n under these c o n d i t i o n s became p r o g r e s s i v e l y l a t e r with i n c r e a s i n g l a t i t u d e of o r i g i n . C alder (1964a) s t u d i e d twenty-three populations of D. glomerata ranging from 32°-66° N l a t i t u d e and 40-44° S l a t i t u d e . I t was found t h a t there was some heading in the year of p l a n t i n g , being g r e a t e s t in the p l a n t s from areas of le s s severe w i n t e r s . Heading was l a t e r in p l a n t s from higher l a t i t u d e in the northern hemisphere. The importance of l a t i t u d i n a l ecotypes has been demonstrated in A l a s k a . Klebesadel e t a l (1964) i n v e s t i g a t e d the w i n t e r s u r v i v a l of several Festuoa rubra L. and Poa pratensis L. accessions under c o n d i t i o n s a t Matanuska, Alaska (61° 34'N). Accessions from below 52° N l a t i t u d e had poor w i n t e r s u r v i v a l . Swedish accessions (ca 56° N l a t . ) had r e l a t i v e l y b e t t e r s u r v i v a l , w h i l e s u r v i v a l was best In accessions from above 60° N l a t i t u d e (Alaska and Ic e l a n d ) . S i m i l a r l y , Klebesadel (1970) found t h a t Vhleumpraten.se L. v a r i e t i e s "Climax" from Canada and " C l a i r " from the conterminous United States had poor w i n t e r s u r v i v a l , w h i l e the v a r i e t y "Engmo" from northern Norway s u r v i v e d w e l l . In the same study i t was found t h a t the "southern-type" Bromus inermis Leyss. v a r i e t y "Achenbach" s u r v i v e d very p o o r l y , while a "northern-type" v a r i e t y "Manchar" s u r v i v e d w e l l . II. Genetic Drift There has been c o n s i d e r a b l e study made of the e f f e c t s of seed production o u t s i d e the region of adaptation on v a r i e t a l s t a b i l i t y ( g e n e t i c d r i f t ) . Knowles and C h r i s t i e (1972) compared c e r t i f i e d seed l o t s of L i n c o l n , Saratoga and F i s c h e r bromegrass (Bromus inermis L.) produced in Canada with o r i g i n a l Breeder o r Foundation seed from t h e i r areas of o r i g i n . 7 Forage and seed production were compared at Saskatoon, while forage production was compared at Guelph. In terms of seed y i e l d a t Saskatoon, one l o t of c e r t i f i e d Saratoga y i e l d e d s i g n i f i c a n t l y l e s s than the Foundation or Breeder l o t s . There was l i t t l e d i f f e r e n c e in forage production a t e i t h e r l o c a t i o n . C o r n e l i u s (1947) found t h a t seed source of Andropogan saoparius a f f e c t e d time of m a t u r i t y , forage y i e l d and winter hardiness. Northern ecotypes matured e a r l i e r , had lower forage y i e l d s and were more w i n t e r hardy than southern ecotypes. The e f f e c t s of area of seed production on v a r i e t i e s of legumes have a l s o been s t u d i e d . Smith (1955) t e s t e d the performance of Ranger a l f a l f a grown in Wisconsin from f i r s t generation seed produced in Montana, Washington, C a l i f o r n i a , A r i z o n a , and Mexico. He found t h a t w i n t e r I n j u r y was g r e a t e s t in p l a n t s grown from seed produced a t southern l o c a t i o n s . Laude and Stanford (1960) s t u d i e d a Ladino c l o v e r v a r i e t y over an 8-degree range of l a t i t u d e . They found t h a t parent clones of the v a r i e t y behaved d i f f e r e n t l y a t each l o c a t i o n , w i t h d i s p r o p o r t i o n a t e amounts of seed and p o l l e n being produced. This was a t t r i b u t e d t o a d i f f e r e n t i a l response t o temperature and photoperiod. Dovrat and Waldman (1966) s t u d i e d several northern adapted v a r i e t i e s and types of Trifolium spp. In I s r a e l . P l a n t s grown from f i r s t generation seed produced In I s r a e l were compared w i t h p l a n t s grown from seed imported from the areas of a d a p t a t i o n . I t was found t h a t there were c o n s i d e r a b l e s h i f t s In f l o r a l response. I I I . Environmental Physiology (a) External Environment Photoperiod and temperature a f f e c t p l a n t growth, s u r v i v a l , and r e p r o d u c t i o n . In r e p r o d u c t i v e development, the t r a n s i t i o n of the v e g e t a t i v e apex t o the r e p r o d u c t i v e s t a t e i s u s u a l l y c o n t r o l l e d by environment, as 8 noted by Cooper (1960). Reproductive development in the Gramineae can be d i v i d e d i n t o three stages: 1. f l o r a l i n d u c t i o n , during which the a p i c a l meristem becomes capable of responding t o the photoperiodic s t i m u l u s , 2. f l o r a l i n i t i a t i o n , 3. subsequent development and e l o n g a t i o n of the i n f l o r e s c e n c e (Cooper, 1960). F l o r a l Induction (stage 1) may r e q u i r e s h o r t photoperiod ( a c t u a l l y long nyctoperiod) and/or low temperature. The environmental requirements f o r f l o r a l i n d u c t i o n of Bromus sp. have been s t u d i e d by several workers. Newell (1951) found t h a t B. inermis s e e d l i n g s grown in the greenhouse re q u i r e d a period of short photoperiod ( n a t u r a l day length a t L i n c o l n , Neb.) in order f o r induction t o occur. A combination of short photoperiod and low temperature i n -creased the number of t i l l e r s produced. E l l i o t t (1966) found t h a t B. inermis s e e d l i n g s grown in the greenhouse could be induced by exposure t o short photoperiod (8 hr) at e i t h e r high (70° F) o r low temperatures (35° F ) . Heading was found t o be more uniform when induction was at the low temperature. Newell (1951) reported no in d u c t i o n of B. inermis under long photoperiod (16 h r ) , whereas E l l i o t t (1966) found t h a t c e r t a i n genotypes were induced under 16 hour photoperiod and continuous l i g h t . The time of f l o r a l i n d u c t i o n of B. inermis under f i e l d c o n d i t i o n s has been recorded. Newell (1951) reported t h a t f l o r a l i n d u c t i o n of B. inermis was e s s e n t i a l l y complete by mid-November at L i n c o l n , Nebraska. Evans and W i l s i e (1946) found t h a t at Ames, Iowa B. inermis had undergone ind u c t i o n by mid-October. Knowles (1961) found t h a t the i n d u c t i o n phase 9 was n e a r l y complete by l a t e October a t Saskatoon, Saskatchewan. An October mean temperature of 37.3°F and 36.4°F was reported t o be more favourable f o r i n d u c t i o n than a mean of 43.4°F. At Beaverlodge, A l b e r t a , E l l i o t t (1966) reported t h a t induction of B. inermis in the f i e l d was complete by September 23. E l l i o t t noted t h a t 89 percent of the s p r i n g seeded p l a n t s had undergone both induction and i n i t i a t i o n p r i o r t o September 23 and bore v a r i o u s l y developed heads. F l o r a l i n i t i a t i o n (stage 2) i s the trans f o r m a t i o n of the induced apex from a v e g e t a t i v e t o a p o t e n t i a l l y r e p roductive s t a t e . There i s con-s i d e r a b l e v a r i a t i o n in the environmental requirements f o r i n f l o r e s c e n c e i n i t i a t i o n in perennial grasses. Those from temperate l a t i t u d e s are g e n e r a l l y long-day p l a n t s (Cooper, 1960). The p a r t i c u l a r photoperiod requirements f o r i n i t i a t i o n of a species vary with v a r i e t y and l a t i t u d e of o r i g i n (Cooper, 1960; Broue and Kawanabe, 1967). t The environmental requirements f o r f l o r a l i n i t i a t i o n of Bromus inermis have been s t u d i e d by many workers. Evans and W i l s i e (1946) found reproductive development of B. inermis t o be best under an 18 hour photo-p e r i o d . A northern-type commercial s t r a i n developed we I I a t e i t h e r 60°F or 80°F, but a southern-type, Achenbach, developed best a t 80°F. G a l l (1947) a l s o found heading of B. inermis t o be best under 18 hour days. Knowles (1961) reported t h a t a 17 hour photoperiod in the greenhouse produced a s a t i s f a c t o r y number of i n f l o r e s c e n e s in f i e l d - i n d u c e d B, inermis. Lower temperatures during the e a r l y stages of growth were more s a t i s f a c t o r y than continuous 70°F temperatures in terms of seed y i e l d . E l l i o t t (1966) found t h a t B. inermis underwent i n i t i a t i o n most r a p i d l y under long days (18 hours) a t low o r high temperatures (50°F o r 70°F). I n i t i a t i o n a l s o occurred under 8 hour days a t 70°F, but heading was c o n s i d e r a b l y dealyed. 10 On the b a s i s of these r e s u l t s , E l l i o t t suggested t h a t the day length e f f e c t on f l o r a l i n i t i a t i o n of bromegrasses was cumulative. The times of i n i t i a t i o n of Bromus sp. under na t u r a l environment have been i n v e s t i g a t e d in va r i o u s l o c a t i o n s . G a l l (1947) found f l o r a l primordia in f i e l d grown B. inermis in e a r l y A p r i l a t Chicago. At Beaverlodge, A l b e r t a (55° 15'N l a t . ) E l l i o t t (1966) reported f l o r a l i n i t i -a t i o n in B. inermis on May 8. Canode e t al (1972) in Washington s t a t e found t h a t B. inermis had i n i t i a t e d f l o r a l primordia by February 12. Hodgson (1966) found t h a t Bromus pumpellianus S c r i b n . underwent f l o r a l i n i t i a t i o n in the f a l l in A l a s k a . Winter s u r v i v a l i s an important c o n s i d e r a t i o n in stud y i n g r e -productive development of perennial grasses, as noted by Klebesadel (1971). This i s e s p e c i a l l y t r u e where f l o r a l primordia are i n i t i a t e d in the f a l l (Hodgson, 1966). E l l i o t t (1966) suggested t h a t f a l l i n i t i a t e d B. inermis meristems were k i l l e d by as much as 5°F of f r o s t . Lawrence and Ashford (1964) found t h a t Russian w i l d ryegrass (Elymus junaeus F i s c h . ) i n i t i a t e d i n f l o r e s c e n c e s in the f a l l a t S w i f t Current, Saskatchewan. These f l o r a l primordia were able t o s u r v i v e the w i n t e r . S i m i l a r f i n d i n g s were made by Johnston and MacDonald (1967). Festuoa saabrella T o r r . was found t o undergo f l o r a l i n i t i a t i o n in the f a l l . I t was a l s o noted t h a t the i n i t i a t e d meristems were e l e v a t e d above the root-stem t r a n s i t i o n over w i n t e r . Photoperiod i s known t o a f f e c t w i n t e r s u r v i v a l . This has been demonstrated in a l f a l f a (Medicago spp.) by Bui a, Smith and Hodgson (1956) and by Hodgson (1964) and in sweetclover {Melilotus spp.) by Hodgson and Bula (1956). Klebesadel (1971) i n v e s t i g a t e d the e f f e c t s of nyctoperiod m o d i f i c a t i o n on several grasses, i n c l u d i n g Bromus spp. a t Palmer, A l a s k a , Extension of the nyctoperiod t o 15 hours between August 25 and mid-October 11 (freeze-up) g r e a t l y improved the w i n t e r s u r v i v a l and subsequent a e r i a l growth of B. -inermis. Shortened nyctoperiod (9 hr) r e s u l t e d In complete w i n t e r - k i l l of B. inermis. Winter s u r v i v a l was poor under normal nycto-period (lengthening from 9 t o 15 hours over the p e r i o d ) . A e r i a l growth and head production of n a t i v e B. pumpellianus was reduced by shortened, lengthened and i n t e r r u p t e d n y c t o p e r i o d s . This demonstrates the dependence of Bromus spp. on photoperiod f o r the development of c o l d r e s i s t a n c e . Klebesadel p o i n t s out t h a t the B. inermis s u r v i v e d b e t t e r when exposed t o extended nyctoperiod s i n c e t h i s c l o s e l y approximated d i u r n a l c o n d i t i o n s during autumn a t i t s l a t i t u d e of o r i g i n , b) Internal Environment Genotype Two climatypes of Bromus inermis e x i s t . Knowles and White (1949) reviewed the o r i g i n s and h i s t o r y of the i n t r o d u c t i o n of B. inermis t o North America. What i s designated as "northern" bromegrass in North America i s thought t o correspond t o a "meadow" group o r i g i n a t i n g in moist h a b i t a t s of c e n t r a l and northern regions of the U.S.S.R. The "southern" type corresponds t o a "steppe" group found in the d r i e r steppe and southern areas of the U.S.S.R. Southern s t r a i n s in the United S t a t e s have a r i s e n from i n t r o d u c t i o n s from France and Hungary, w h i l e northern s t r a i n s r e s u l t e d from i n t r o d u c t i o n s from R u s s i a . Knowles and White (1949) reported t h a t northern and southern types of bromegrass produced s i m i l a r amounts of forage when t e s t e d a t nine l o c a t i o n s in Western Canada. Seed y i e l d s of the southern types were found t o be lower than those of northern types. Newell and Keim (1943) found t h a t southern types y i e l d e d more seed than northern types in Nebraska. 12 ^ Noteworthy genotypic v a r i a t i o n s w i t h i n B. -inermis v a r i e t i e s have a l s o been reported. E l l i o t t (1966) demonstrated two d i s t i n c t genotypes w i t h i n the v a r i e t y " C a r l t o n " . A " s p r i n g " genotype which had no requirement f o r s h o r t photoperiod in order t o undergo f l o r a l i n d u c t i o n , and a "w i n t e r " genotype which had s p e c i f i c photoperiod requirements f o r i n d u c t i o n . Three v a r i e t i e s of the B. pumpellianus species are recognized, which are: pumpellianus, arotiaus (Shear) Pors., and villosissimus H u l t . B. pumpellianus i s widely d i s t r i b u t e d in A l a s k a , the Yukon, the Northwest T e r r i t o r i e s as f a r East as Hudson's Bay, in the Canadian P r a i r i e s , and South in the United States as f a r as Colorado in the Rocky Mountains (Hulten, 1968; Hitchcock, 1950). Physiological Age In many perennial grass species i t has been shown t h a t a c e r t a i n p h y s i o l o g i c a l age must be a t t a i n e d before f l o r a l i n d u c t i o n can occur. This i s commonly discussed in terms of j u v e n i l i t y (Sacks, 1972). Calder (1964b) found t h a t Daotylis glomerata r e q u i r e d a j u v e n i l e phase of about f i v e weeks before i n d u c t i o n of the f l o r a l s t a t e could occur. McCown and Peterson (1964) found t h a t four-week-old p l a n t s of Lolium perenne responded t o i n -du c t i v e treatments by producing more heads than d i d p l a n t s grown from germinating seeds exposed t o the same c o n d i t i o n s . Lamp (1952) found t h a t t i l l e r s of Bromus inermis had from 5-14 leaves present before f l o r a l i n i t i a t i o n . He reported t h a t 80 percent of f e r t i l e t i l l e r s s t u d i e d were in the 7-10 leaf range. E l l i o t t (1966) found t h a t f l o w e r i n g culms of B. inermis bore 6 t o 7 leaves when i n i t i a t e d in long days. Flowering culms bore an average of 10 leaves when i n i t i a t e d i n warm, short days, From t h i s i t was concluded t h a t the v e g e t a t i v e apex had at l e a s t 6 t o 7 leaf i n i t i a l s p r i o r t o i n i t i a t i o n , with more where i n i t i t i o n was delayed. 13 IV. Apical Development a) Ontogeny Leaf primordia a r i s e as c r e s c e n t i c ridges a l t e r n a t e l y on e i t h e r side of the veg e t a t i v e a p i c a l meristem in the Gramineae. The t r a n s i t i o n from the ve g e t a t i v e t o the reproductive s t a t e i s marked by the appearance of spike l e t primordia in the "double r i d g e stage". If the i n f l o r e s c e n c e i s a s p i k e , s p i k e l e t primordia a r i s e in the a x i l s of the l e a f i n i t i a l s . In i n f l o r e s c e n c e s with secondary branching, the branch primordia are l e s s numerous, and g e n e r a l l y develop in acropetal s u c c e s s i o n . As the s p i k e l e t s become more developed, flower primordia develop. Development of the f l o r e t s continues as the i n f l o r e s c e n c e elongates (Barnard, 1964). b) Inflorescence Development - Rating Systems Numerous s t u d i e s have been made of the development of the i n f l o r e s c e n c e of Gramineae. Such s t u d i e s n e c e s s i t a t e a system f o r c l a s s i -f y i n g the va r i o u s "stages" in the development. Although the development of the i n f l o r e s c e n c e i s e s s e n t i a l l y a continuous process, c e r t a i n d e f i n i t e stages in the developmental sequence are e v i d e n t . Anderson (1952) developed two s c a l e s f o r r a t i n g i n f l o r e s c e n c e development of oats and b a r l e y . The s c a l e f o r b a r l e y c o n s i s t e d of stages numbered 0 t o 13, 0 being the developing apex in the k e r n e l , and 13 being a n t h e s i s . The s c a l e f o r oats was s i m i l a r , having 11 r a t h e r than 14 stages. J e a t e r (1956) used a s c a l e of 10 t o r a t e the developmental stages of perennial grasses. Stages 1-8 described the development of the apex, stages 9 and 10 were the boot stage and ear emergence r e s p e c t i v e l y . Bommer (1959) used a s c a l e of 6 t o rate developmental stages in several perennial grass s p e c i e s . Stage 1 represented a s h o r t , v e g e t a t i v e apex, w h i l e stage 6 represented the extension of the 14 i n f l o r e s c e n c e . Hodgson (1966) c l a s s i f i e d shoot apices as v e g e t a t i v e , t r a n s i t i o n a l o r rep r o d u c t i v e while studying i n i t i a t i o n times in Alaskan grasses. Johnston and MacDonald (1967) used a s c a l e o f s i x t o rate the development of the i n f l o r e s c e n c e of Festuaa scabrella. Stages 1 and 2 described the ve g e t a t i v e apex, while stages 3 t o 6 described the reproductive apex. L a t t i n g (1972) used a s c a l e of 12 stages t o d e s c r i b e the development of the grass i n f l o r e s c e n c e . Stages 0-7 represented the development of the v e g e t a t i v e and re p r o d u c t i v e apex p r i o r t o e l o n g a t i o n of the i n f l o r e s c e n c e , w h i l e stages 8-11 represented e l o n g a t i o n of the i n f l o r e s c e n c e , emergence, and a n t h e s i s . V. Dates of Seeding R e s u l t s of research i n t o seeding times of grasses can g e n e r a l l y only be a p p l i e d in the area where the research was undertaken. Van Keuren and Canode (1963) s t u d i e d s p r i n g and f a l l seeding of perennial grasses under i r r i g a t i o n a t P r o s s e r , Washington. For Bromus inermis L. they concluded t h a t f a l l seeding (September 23) was b e t t e r than s p r i n g seeding (March 10). In A l a s k a , Klebesadel (1970) found t h a t seed y i e l d s of several Bromus s p e c i e s in the year f o l l o w i n g seeding d e c l i n e d with p r o g r e s s i v e l y l a t e r seeding dates. The d e c l i n e in y i e l d s was dramatic when seeding was done l a t e r than the end of May. 15 MATERIALS AND METHODS I. Plant Material Two Canadian v a r i e t i e s of Bromus inermis were used. These were "Redpatch", a southern type and " C a r l t o n " , a northern type. Foundation seed l o t s were used t o provide the necessary p l a n t m a t e r i a l . The Bromus pumpellianus p l a n t s used came from c o l l e c t i o n s made by H. Vaartnou and W. P r i n g l e of the Research S t a t i o n , Beaverlodge, These p l a n t s had been growing in a hol d i n g nursery a t Beaverlodge f o r three years p r i o r t o the s t a r t of t h i s study. II. Determination of Initiation Time T i l l e r s of Bromus pumpellianus and Bromus inermis were c o l l e c t e d f o r d i s s e c t i o n and r a t i n g of a p i c a l meristems. P l a n t s of B. pumpellianus from three l o c a t i o n s were s t u d i e d . One came from 45 miles East of Smithers, B.C. (54° 35'N l a t . ) , one from 30 miles West of Worsley, A l b e r t a (56° 35'N), and one from M i l e 1019, Alaska Highway, Yukon (60° 46'N). In the s p r i n g of 1971, t i l l e r s of the three B. pumpellianus p l a n t s under study were c o l l e c t e d from two n u r s e r i e s of n a t i v e grasses a t the Research S t a t i o n , Due t o a shortage of m a t e r i a l , sample s i z e s were s m a l l . M a t e r i a l from these p l a n t s was v e g e t a t i v e l y propagated in growth c a b i n e t s and greenhouse in order t o increase the amount of m a t e r i a l a v a i l a b l e f o r study. This m a t e r i a l was t r a n s p l a n t e d t o a small nursery arranged in a 90 x 90 cm spacing. S u f f i c i e n t m a t e r i a l of the three p l a n t s was thus obtained. Subsequent c o l l e c t i o n s of B. pumpellianus t i l l e r s were made from t h i s nursery. In the s p r i n g of 1971 t i l l e r s of B. inermis v a r i e t i e s C a r l t o n and 16 Redpatch were c o l l e c t e d from a nursery e s t a b l i s h e d in 1969. C o l l e c t i o n s in the f a l I of 1971 and the s p r i n g of 1972 were made from the 1971 "dates of seeding" t r i a l . T i l l e r s c o l l e c t e d in the f a l l of 1972 came from the 1972 "dates of seeding" t r i a l . In the f a l l of 1972, t i l l e r s of P o l a r bromegrass, which has both B. inermis and B. pumpellianus parentage (Wilton e t a l . 1966), were added to the t e s t using m a t e r i a l from an e s t a b l i s h e d f i e l d p l o t a t Beaverlodge. T i l l e r samples were collected a t 4-7 day I n t e r v a l s in the s p r i n g . Sampling s t a r t e d as soon as p o s s i b l e a f t e r the s t a r t of growth and con-ti n u e d u n t i l the m a j o r i t y of t i l l e r s c o l l e c t e d had f l o r a l p r i m o r d i a . In the f a l l , sampling s t a r t e d in mid-September and continued u n t i l s o i l freeze-up ( e a r l y November). T i l l e r s were dug from rows or spaced p l a n t s in the f i e l d , placed in l a b e l l e d c o n t a i n e r s , and tr a n s p o r t e d t o the l a b o r a t o r y . Here a l l s o i l was removed by washing with tap water. Ten t i l l e r s were randomly s e l e c t e d from each clump. The s e l e c t e d t i l l e r s were trimmed t o a length of approximately 5 cm, with care being e x e r c i s e d t o ensure t h a t the a p i c a l meristems were not d i s t u r b e d . The t i l l e r s were then placed in 17 x 60 mm l a b e l l e d v i a l s . M a t e r i a l which was t o be d i s s e c t e d immediately was stored in water and r e f r i g e r a t e d (max. 24 h r ) . For longer term sto r a g e , t i l l e r s were placed in Carnoy s o l u t i o n , 3:1 e t h y l a l c o h o l : a c e t i c a c i d . The d i s s e c t i o n of t i l l e r s was performed a t a m a g n i f i c a t i o n of 10X t o 16X using a s t e r e o s c o p i c d i s s e c t i n g microscope. T i l l e r s were s l i c e d l o n g i t u d i n a l l y above the uppermost node. Leaves were c a r e f u l l y peeled back and removed u n t i l the a p i c a l meristem was f u l l y exposed. The meristems were then rated as t o t h e i r stage of development. The r a t i n g s c a l e used was one developed by C. R. E l l i o t t w h i l e s t u d y i n g f l o r a l 17 i n i t i a t i o n in perennial grasses a t Beaverlodge. A s c a l e of 1 t o 8 was used, 1 being a j u v e n i l l e v e g e t a t i v e meristem and 8 being a f u l l y developed f l o r a l primordium (Fi g u r e 1). T i l l e r e l o n g a t i o n beyond one node was a l s o noted. Heading and an t h e s i s dates of C a r l t o n and Redpatch were recorded. The heading dates of the B. pumpellianus p l a n t s were recorded in 1971 and 1972, and the date of a n t h e s i s was noted in 1972. III. Dates of Seeding A dates of seeding t r i a l was seeded a t Beaverlodge in 1971 and again in 1972. This t r i a l c o n s i s t e d of eleven grasses, i n c l u d i n g Bromus inermis v a r i e t i e s C a r l t o n and Redpatch, seeded at approximately two-week i n t e r v a l s from e a r l y May t o October. The 1971 t r i a l had 12 dates from May 6 t o Oct. 13, and the 1972 t r i a l had 8 dates, from May 9 t o September 13. P l o t s were l a i d out in a randomized block d e s i g n , with f o u r r e p l i -c a t i o n s . Each u l t i m a t e p l o t c o n s i s t e d of four 6.2 meter rows spaced 30 cm apa r t . A seed harvest was taken from the 1971 seeding. Seed was harvested and bagged when mature. A f t e r a i r d r y i n g , the samples were threshed and the weight of cl e a n seed determined. A d d i t i o n a l data c o l l e c t e d included heading and f l o w e r i n g dates, harvest dates, and stage of development going i n t o w i n t e r in the year of establishment. IV. Insect Damage Insect larvae were discovered during the course of d i s s e c t i o n to expose a p i c a l meristems. Observations on the extent and l o c a t i o n of damage were made on a l l m a t e r i a l c o l l e c t e d during the f a l l o f 1971 and Developmental stages of the bromegrass aoex. Stages 1-3 vegetative, stages 4-8 reproductive (prior to stem elongation) 19 Figure 1 (continued) during the sp r i n g and f a l I of 1972. Samples of Bromus inermis and B. pumpellianus sod were sent t o the A g r i c u l t u r e Canada Entomology Research I n s t i t u t e in Ottawa. Larvae from these samples were s u c c e s s f u l l y reared t o adulthood and i d e n t i f i e d . 21 RESULTS AND DISCUSSION I. Initiation Times Inflorescence development progressed r a p i d l y in Bromus inermis a f t e r A p r i l 26 in 1971 (Figu r e 2 ) . Redpatch had more r e p r o d u c t i v e meristems than C a r l t o n a t the s t a r t of the sampling ( A p r i l 26), but sub-sequent development of the two v a r i e t i e s was very s i m i l a r , with p r i m o r d i a l development being complete by May 10. The B. pumpellianus accession from 54° 35*N l a t . had no meristems in the rep r o d u c t i v e s t a t e on A p r i l 26. Development was r a p i d a f t e r t h i s time, with peak development being a t t a i n e d by May 5. The accession from 56° 35'N had f u l l y developed p r i -mordia by A p r i l 26, w h i l e the accession from 60° 46'N was f u l l y developed by A p r i I 28. Figure 3 shows the development of B. inermis and B. pumpellianus over the pe r i o d from September 1971 t o May 1972. C a r l t o n and Redpatch had comparatively low percentages of meristems in the re p r o d u c t i v e s t a t e in the f a l l of 1971. The percentages were lower on A p r i l 20, 1972 than they were on November 1, 1971. As in the s p r i n g of 1971, C a r l t o n and Redpatch developed r a p i d l y a f t e r A p r i l 26, with the m a j o r i t y of t i l l e r s sampled having we I I-developed primordia by May 15. The three B. pumpellianus accessions achieved a high l e v e l of repr o d u c t i v e development by November 1, 1971. The accessions from 54° 35'N and 60° 46'N had low percentages of primordia in the rep r o d u c t i v e s t a t e on September 20, but had r i s e n t o 56 and 89$ r e s p e c t i v e l y by November 1. The accession from 56° 35'N had 74$ of i t s a p i c e s in the reproductive phase on September 20, and 100? by November 1. The m a j o r i t y of a p i c e s were s t i l l in the rep r o d u c t i v e phase on A p r i l 20, 1972. The p a t t e r n of development of C a r l t o n and Redpatch in the f a l l of 1972 was s i m i l a r t o t h a t of the f a l l of 1971 (Figu r e 4 ) . The Figure 2. Relationship between stage of development and collection date, spring 1971. » — I — — 1 — , 1—, J t I Sept 2 0 Oct 4 Oct 18 Nov I April 2 0 26 May I 5 10 15 M FALL 1971 SPRING 1972 Figure 3„ Relationship between stage of apex development and collection date, Fall 1971 - Spring 1 24 6 0 Sept 2 9 Oct 13 Nov 9 Figure 4. Relationship between stage of apex development and collection date, Fall 1972. 25 development of B. pumpellianus s t a r t e d out the same as In 1971, t h a t Is the accession from 56° 35'N was r e l a t i v e l y more developed than those from 54° 35'N and 60° 46'N. However, a f t e r an I n i t i a l r i s e in the percentage of meristems in the rep r o d u c t i v e phase, the percentages dropped q u i t e markedly, e s p e c i a l l y in the accessions from 54° 35'N and 60° 46'N. P o l a r bromegrass showed a sharp increase in the percentage of meristems in the re p r o d u c t i v e s t a t e between September 29 and October 13, 1972 ( f i g u r e 4 ) . There was a s l i g h t increase by the next sampling date (November 9 ) . The r e s u l t s i n d i c a t e t h a t Bromus inermis undergoes i n i t i a t i o n in the s p r i n g a t Beaverlodge. This concurs with the f i n d i n g s of E l l i o t t (1966), who reported f l o r a l i n i t i a t i o n of B. inermis by May 8. The time of i n i t i a t i o n of B. inermis i s much l a t e r a t Beaverlodge than a t Chicago, as reported by G a l l (1947) o r a t Pr o s s e r , as reported by Canode e t a l . (1972). This i s t o be expected, due t o the s h o r t e r growing season a t Beaverlodge. There was not a great deal of f a l l i n i t i a t i o n of B. inermis, the maximum being 25% as compared t o the 89% reported by E l l i o t t (1966). There was not a dramatic r e d u c t i o n i n the number of t i l l e r s in the r e -productive s t a t e a f t e r the f i r s t k i l l i n g f r o s t (28°F) as was found by E l l i o t t . The percentage of i n i t i a t e d t i l l e r s was lower In the s p r i n g of 1972 than i t was a t the time of the l a s t c o l l e c t i o n date in the f a l l of 1971, which could i n d i c a t e some k i l l i n g of rep r o d u c t i v e a p i c e s . The f r o s t damage in the f a l l , i f any, may not have been r e a d i l y e v i d e n t , s i n c e the t i l l e r s were placed in p r e s e r v a t i v e a t the time of c o l l e c t i o n , which would prevent the development of damage symptoms. Both C a r l t o n and Redpatch underwent r a p i d r e p r o d u c t i v e develop-ment a f t e r A p r i l 26 in 1971 and 1972. E l l i o t t (1966) found t h a t B. inermis 26 s t a r t e d growth in the s p r i n g when the d a i l y mean temperature was a p p r o x i -mately 38°F. Using 38°F as a base temperature, there were 76 degree-days above t h i s temperature between A p r i l 1 and 26 of 1971, and 15 degree-days between A p r i l 1 and 26, 1972 (Table 1). The day length ( d u r a t i o n of c i v i l l i g h t ) a t Beaverlodge on A p r i l 26 i s 16.2 hours (Table 1). At Chicago (42°N l a t . ) , G a l l (1947) reported the appearance of f l o r a l p rimordia of B. inermis in e a r l y A p r i l . At t h i s time the c i v i l l i g h t d u r a t i o n a t Chicago i s approximately 13.8 hours. At Prosser (46°N l a t . ) , Canode e t a l (1972) reported i n i t i a t i o n of B. inermis by February 12. At t h i s time the c i v i l l i g h t d u r a t i o n i s about 11.3 hours. I t i s thus apparent t h a t B. inermis can undergo i n i t i a t i o n over a c o n s i d e r a b l e range of photoperiod. This concurs with the f i n d i n g s of E l l i o t t (1966), who found t h a t B. inermis underwent i n i t i a t i o n under both 8 and 16 hour photoperiods in the greenhouse. I t would appear t h a t temperature must be the prime f a c t o r governing s p r i n g f l o r a l i n i t i a t i o n in B. inermis. The temperature t h r e s h o l d must be f a i r l y low, s i n c e only 15 degree-days above 38°F in the s p r i n g of 1972 was s u f f i c i e n t t o s t a r t the i n i t i a t i o n process. The i n i t i a t i o n process i s not independent of photoperiod, however. If i t were, B. inermis would have s t a r t e d i n i t i a t i o n by mid-A p r i l a t Beaverlodge in 1971, by which time there had been 17 degree-days above 38°F (Table 1), and the s o i l had thawed. I t would appear t h a t a t sh o r t e r photoperiods a higher temperature i s required f o r i n i t i a t i o n . T h is i s born out by E l l i o t t ' s (1966) r e s u l t s . He found t h a t although B. inermis could be i n i t i a t e d under 8 hour photoperiods, a temperature of 70°F was r e q u i r e d . Under 18 hour photoperiod, i n i t i a t i o n occurred a t both 50° and 70°F. The r e s u l t s show no I n d i c a t i o n t h a t the requirements f o r f l o r a l i n i t i a t i o n of the "southern-type" Redpatch brome are d i f f e r e n t from those I Table 1. C i v i l daylength, d a i l y mean temperatures and degree-days above 38°F, A p r i l 1971 and 1972 at Beaverlodge. 1971 1972 C i v i l l i g h t Date Da i l y mean °F Degree- D a i l y mean Degree-days F days d u r a t i o n hr. A p r i l 1 31 3 14.2 2 32 10 14.3 3 31 9 14.4 4 38 17 14.5 5 41 3 17 14.6 6 44 6 37 14.6 7 36 33 14.7 8 32 28 14.8 9 32 32 14.9 10 22 30 15.0 11 28 30 15.0 12 37 29 15.1 13 32 31 15.2 14 46 8 37 15.3 15 34 31 15.4 16 30 28 15.4 17 33 29 15.5 18 34 36 15.6 19 43 5 44 6 15.7 20 45 7 34 15.8 21 41 3 31 15.8 22 45 7 31 15.9 23 47 9 36 16.0 24 45 7 4 1 3 16.1 25 47 9 40 2 16.2 26 50. Total 12 42 4 76 15 16.2 28 of the "northern-type" C a r l t o n . Seed y i e l d s of many "southern-type" v a r i e t i e s are reported t o be lower than those of "northern-type" v a r i e t i e s at Beaverlodge ( E l l i o t t , 1972). The low-seed y i e l d of "southern-types" may be due t o other y i e l d components which are a d v e r s e l y a f f e c t e d by the northern photoperiod and temperature. I t a l s o could be due to g e n e t i c f a c t o r s - the "southern-types" p o s s i b l y have a lower seed y i e l d p o t e n t i a l , as suggested by Knowles and White (1949). B. pumpellianus undergoes over 50% f l o r a l i n i t i a t i o n in the f a l l a t Beaverlodge, which concurs with Hodgson's (1966) r e s u l t s in A l a s k a . The i n i t i a t i o n process s t a r t e d in September, as i n d i c a t e d in Figures 3 and 4. During September the photoperiod ( c i v i l l i g h t d uration) at Beaverlodge ranges from 15.1 t o 12.9 hours (Table 2 ) . The monthly mean temperature was 42.2°F in 1972, and 46°F in 1971. As can be seen from Table 2, the c i v i l day length a t 54° 35'N l a t i t u d e (Smithers area) and a t 56° 35'N (Worsley area) i s s i m i l a r t o t h a t a t Beaverlodge. The c i v i l day length Is longer in e a r l y September a t 60° 46'N ( M i l e 1019), but Is s i m i l a r by the end of September, Consequently, the three B. pumpellianus accessions had day lengths s i m i l a r t o t h e i r areas of o r i g i n during the period (September) in which they were undergoing f l o r a l i n i t i a t i o n . The 4 degree d i f f e r e n c e in the September mean temper-ature of 1971 and 1972 seems t o have had no e f f e c t on the development p a t t e r n of B. pumpellianus. The d e c l i n e in the percentages of r e p r o d u c t i v e meristems on the November 9, 1972 c o l l e c t i o n date ( F i g u r e 4) was probably not due t o c o l d damage t o I n i t i a t e d meristems, as no evidence of such damage was found during the d i s s e c t i o n s . It i s probable t h a t day length Is the prime f a c t o r governing f l o r a l i n i t i a t i o n In B, pumpellianus In the autumn. The i n i t i a t i o n process Table 2. C i v i l daylength (hours) a t Beaverlodge, Smithers, Worsley and M i l e 1019 in September and October. Location Date Beaverlodge Smithers Worsley M i l e 1019 1 15.1 14.9 15.2 15.7 5 14.8 14.7 14.9 15.3 9 14.5 14.4 14.5 14.9 13 14.1 14.1 14.2 14.5 17 13.8 13.8 13.9 14.1 21 13.5 13.5 13.6 13.8 25 13.2 13.2 13.3 13.4 29 12.9 12.9 12.9 13.0 1 12.8 12.8 12.8 12.8 5 12.5 12.5 12.5 12.5 9 12.2 12.2 12.2 12.2 13 11.9 1 1 .9 11 .9 11.8 17 11 .6 11.7 11 .6 11.4 21 11.3 11 .4 11.3 11.1 25 11.1 11.2 11.0 10.8 29 10.9 10.9 10.8 10.4 Adapted from Table 171 and 172 Smithsonian M e t e o r o l o g i c a l Tables, Smithsonian I n s t i t u t e , Washington, 1963. Table 3. Dates of heading, a n t h e s i s and m a t u r i t y of Bromus inermis and B. pumpellianus. Year V a r i e t y / Heading Date of M a t u r i t y ecotype Date A n t h e s i s 1971 C a r l t o n Redpatch 54°35» 56°35' 60°46f 1972 C a r l t o n Redpatch 54°35' 56°35• 60°46» 2/6 14/7 11/8 2/6 10/7 11/8 25/5 - — 28/5 - -7/6 6/7 21/8 7/6 6/7 21/8 7/6 27/6 -7/6 27/6 -14/6 6/7 -30 s t a r t s under long-day c o n d i t i o n s . This i s born out by the r e s u l t s of Klebesadel (1971), who found t h a t n a t u r a l l y lengthening nyctoperiods (shortening day length 15-9 hours) in the f a l l were necessary f o r proper heading of B. pumpellianus in A l a s k a . Klebesadel a l s o showed w i n t e r s u r v i v a l t o be r e l a t e d t o f a l l n yctoperiod p r i o r t o freeze-up. Temper-ature i s the important f a c t o r in determining the s t a r t of development in the s p r i n g . There i s v a r i a b i l i t y in the behavior of the three B. pumpellianus a c c e s s i o n s . The p l a n t from 54° 35'N (Smithers a r e a ) , f o r example, under-went i n i t i a t i o n i n the s p r i n g of 1971, and in the f a l l of 1971 and 1972. The p l a n t from 56° 35'N (Worsley area) underwent i n i t i a t i o n e a r l i e r than the o t h e r s . This seems t o be c o n t r a r y t o what would be expected -i n i t i a t i o n should be e a r l i e r in the accession from M i l e 1019 due t o the sho r t growing season (54 days) experienced in t h a t area. An expanded study of t h i s type using a l a r g e r number of accessions from v a r i o u s l a t i t u d e s would p o s s i b l y give more c o n s i s t a n t r e s u l t s . P o l a r bromegrass, with i t s mixed B. inermis and B. pumpellianus a n c e s t r y , seems t o behave l i k e B. pumpellianus with respect t o i n i t i a t i o n time. F a l l i n i t i a t i o n , along with c o l d r e s i s t a n c e , make P o l a r well-adapted t o the s h o r t growing season and c o l d w i n t e r s of the North. P o l a r o u t -y i e l d s both C a r l t o n and Redpatch in terms of seed production a t Beaverlodge ( E l l i o t t , 1972). Table 3 shows the heading and an t h e s i s dates of B. inermis and B. pumpellianus in 1971 and 1972. In 1971, C a r l t o n and Redpatch headed a t the same time. The B. pumpellianus accession from the Worsley area headed 8 days e a r l i e r , w h i l e the one from M i l e 1019 headed 5 days e a r l i e r . The date of a n t h e s i s of Redpatch was e a r l i e r than t h a t of C a r l t o n in 1971, but 31 the same in 1972. Heading dates f o r a l l but the B. pumpellianus accession from M i l e 1019 were the same in 1972. The time from heading t o a n t h e s i s was s h o r t e r f o r B. pumpellianus than f o r B. inermis (21 vs 29 days). Knowles and White (1949) reported t h a t southern-types of B. inermis flowered two t o four days l a t e r than the northern-types at Saskatoon. S i m i l a r l y , Klebesadel (1970) reported e a r l i e r a n t h e s i s and maturity in northern-adapted bromegrasses. However, a t Beaverlodge, i t i s reported t h a t the average maturity date of Redpatch i s August 10, as opposed t o August 15 f o r C a r l t o n ( E l l i o t t , 1972). Other southern s t r a i n s , with the exception of "S.A.C." and "Saratoga", matured as l a t e o r l a t e r than C a r l t o n a t Beaverlodge. Newell and Keim (1943) reported northern s t r a i n s t o be l a t e r than southern s t r a i n s in terms of s p r i n g growth in Nebraska. I t would appear t h a t there are both v a r i e t a l and geographic f a c t o r s i n f l u e n c i n g a n t h e s i s and ma t u r i t y dates of the two types of B. inermis. There seems t o be l i t t l e d i f f e r e n c e in heading, a n t h e s i s and matu r i t y dates of C a r l t o n and Redpatch bromegrass. The more rapi d development of B. pumpellianus i s s i m i l a r t o t h a t found in Agropyron traohyaaulum (unpublished data, Research S t a t i o n , Beaverlodge). P l a n t s of A. traohyaaulum from the North matured more r a p i d l y than d i d those from the South. In g e n e r a l , i t appears t h a t n a t i v e perennial grasses of northern regions undergo f l o r a l i n i t i a t i o n in the f a l l and/or mature more r a p i d l y than introduced domestic s p e c i e s . Johnston and MacDonald (1967) suggested t h a t f a l l sampling and in s p e c t i o n of grass species which undergo f l o r a l i n i t i a t i o n in the f a l l c o uld be used t o p r e d i c t a c t u a l o r p o t e n t i a l seed production in the f o l l o w i n g year. Such a procedure could be useful in the case of P o l a r bromegrass and B. pumpellianus. However, I t i s doubtful whether such a 32 procedure could be used t o p r e d i c t a c t u a l production with any degree of accuracy, s i n c e , as in the case of C a r l t o n and Redpatch bromegrass, the degree and time of f l o r a l development were q u i t e s i m i l a r , yet seed y i e l d s were d i f f e r e n t . I I . Dates of Seeding There were no s i g n i f i c a n t d i f f e r e n c e s in the seed y i e l d of C a r l t o n p l o t s seeded between May 6 and J u l y 30, 1971 (Table 4 ) . The y i e l d of the p l o t seeded on August 13 was s i g n i f i c a n t l y lower, and p l o t s seeded a f t e r t h i s date produced no seed. The seed y i e l d s of Redpatch were le s s than those of C a r l t o n , and there was not a sharp demarcation between higher and lower y i e l d i n g p l o t s . Y i e l d s were highest f o r seeding dates between May 19 and June 21. The y i e l d was low f o r the August 13 seeding, and as in the case of C a r l t o n , p l o t s seeded a f t e r t h i s date produced no seed. The y i e l d s of both C a r l t o n and Redpatch followed the same general pat t e r n ( F i g u r e 5 ) . There were increases in y i e l d with p r o g r e s s i v e -ly l a t e r seeding date a f t e r May 1, followed by a sharp drop f o r the J u l y 7 seeding date. The y i e l d s recovered t o near the previous maximum f o r the J u l y 19 date, followed by a sharp d e c l i n e . The sharp d e c l i n e in y i e l d f o r the J u l y 7 seeding date was not r e l a t e d t o any observable d i f f e r e n c e in stand o r developmental stage p r i o r t o freeze-up in the establishment year, P l o t s of C a r l t o n t h a t produced seed in 1972 had developed more than one t i l l e r per p l a n t p r i o r to freeze-up in the f a l l of 1971 (Table 4 ) . The s i t u a t i o n was s i m i l a r f o r Redpatch, except t h a t the August 13 seeding reached only the s i n g l e - t i l l e r , 4 - l e a f stage but s t i l l produced seed In 1972. Lamp (1952) reported t h a t t i l l e r s of B. inermis had 5-14 leaves Table 4 . F a l l growth and subsequent seed y i e l d s of Redpatch and C a r l t o n bromegrass seeded at va r i o u s dates in 1971. Car I ton Redpatch  F a l l 1971 1972 F a l l 1971 1972 Date of I Stage of Heading Harvest Seed Y i e l d % Stage of Heading Harvest Seed Y i e l d Seeding Heading development date date kg/ha Heading development date date kg/ha May 6 5 Many t i 1 l e r s 7 June 21 Aug. 687 a 7 Many t i 1 l e r s 7 June 21 Aug. 227 be 19 4 II ii II it it ii 734 a 9 ii it it II II it 302 ab 28 3 II II ii ti it I I 928 a 2 ii it II it II n 321 ab June 21 Trace Many t i 1 l e r s 7 June 21 Aug. 843 a Trace Many t i 1 l e r s 7 June 21 Aug. 374 a J u l y 7 ii II n n it II I I 569 a - it I I I I ti it II 169 c 19 ii 8 t i 1 l e r s it II ii I I 943 a - ti I I II it ti it 367 a 30 - n II 7 June 21 Aug. 590 a - 2 t i 1 l e r s 7 June 21 Aug. 120 cd Aug. 13 - 2 " I I it it II 64 b - 4 leaves 9 June it it 18 d 25 - 3 leaves no heads - - - 3 " no heads -Sept. 6 - 2 " II II - - - 2 " it ti -17 - 1 leaf * - 1 leaf * Oct. 13 no emergence * no emergence * Means in the same column bearing the same l e t t e r do not d i f f e r s i g n i f i c a n t l y a t the 5% 1 evel of s i g n i f i c a n c e according t o Duncan's M u l t i p l e Range Test. * P l o t s d iscarded due t o incomplete establishment. 1000-May I June I July I August I Sept I Oct I Nov I Date (197!) Figure 5. 1971 precipitation and 1972 seed yield of Carlton and Redpatch bromegrass seeded at various dates in 1971. 35 p r i o r t o i n i t i a t i o n , w h i l e E l l i o t t (1966) s t a t e d t h a t at l e a s t 6 t o 7 leaf i n i t i a l s were necessary p r i o r t o f l o r a l i n i t i a t i o n . I t i s p o s s i b l e t h a t the minimum leaf requirement i s d i f f e r e n t f o r Redpatch. The time of i n i t i a t i o n of the August 13 seeding date of Redpatch was the same as t h a t f o r the e a r l i e r seeding dates, r u l i n g out the p o s s i b i l i t y of s p r i n g i n -d u c t i o n . No p l o t s of C a r l t o n seeded a f t e r J u l y 18 or Redpatch seeded a f t e r J u l y 28, 1972 had surpassed the s i n g l e - t i l l e r stage by freeze-up in the f a l l of 1972 (Table 5 ) . This would suggest t h a t p l o t s seeded a f t e r these dates w i l l produce no seed in 1973. It i s evident t h a t year t o year c l i m a t i c v a r i a t i o n has an e f f e c t on the amount of development in the establishment year. The May t o October p r e c i p i t a t i o n a t Beaverlodge in 1971 and 1972 i s shown in Table 6. P r e c i p i t a t i o n during the May-October period of 1971 exceeded the 45-year average by almost 10 cm. The months of June, J u l y and September exceeded the averages f o r these months, w h i l e the other months were below the averages. May-October p r e c i p i t a t i o n in 1972 was very near the 45-year average, with the months of September and October being above average. In both years the p r e c i p i t a t i o n in May was very much below the average f o r the month. The above-average p r e c i p i t a t i o n of the 1971 growing season seems to have been more f a v o r a b l e f o r the development of bromegrass as compared t o the near-average p r e c i p i t a t i o n of 1972. Although the t o t a l p r e c i p i t a -t i o n of the 1972 growing season was near normal, the low amount of r a i n f a l l in May made moisture c o n d i t i o n s less f a v o r a b l e in the f i r s t p a r t of the season. I t was not u n t i l September t h a t the d e f i c i t was made up. Con-sequently, the response of C a r l t o n and Redpatch in 1971 would perhaps be more normal s i n c e the p r e c i p i t a t i o n r e c e i v e d in the e a r l y p a r t of the growing season was higher. 36 Table 5. F a l l growth of C a r l t o n and Redpatch bromegrass seeded a t v a r i o u s dates in 1972. Date of Seeding Car 1 ton Redpatch % Heading Head- . . , date ing Stage of development i Head-ing Head ing date Stage of development May 9 10 18 J u l y * Many t i 1 l e r s 10 18 J u l y * Many t i 1 l e r s 23 10 9 Aug. II it 10 9 Aug. I I I I June 20 1 28 Aug. ii II 2 10 Sept. I I it J u l y 5 - 3 t i 1 l e r s - - 4 t i 1 l e r s 18 - 2 11 - - 2 11 28 - 3 leaves - - 2 " Aug. 17 - 2 " - - 3 leaves Sept. 13 no emergence no emergence * Anthesis August 28 Table 6 . May-October p r e c i p i t a t i o n 1971, 1972 and 45 year average a t Beaverlodge. 1971 1972 45 year average cm cm cm May 0.18 0.08 4.04 June 17.55 5.41 5.44 J u l y 5.84 5.79 6.20 Aug. 3.89 4.62 4.88 Sept. 9.19 7.54 4.15 Oct. 1 .09 4.45 3.07 Total 37.34 27.89 27.78 37 On the b a s i s of these r e s u l t s , i t could be s a i d t h a t C a r l t o n bromegrass should be seeded before the end of J u l y , and Redpatch should be seeded a f t e r mid-May but before mid-July. Accurate recommendations cannot be made on t h i s amount of data. Three seed crops of bromegrass are normally harvested p r i o r t o r e j u v e n a t i o n or re-seeding. The t h r e e -year average of seed y i e l d c ould q u i t e c onceivably give d i f f e r e n t r e s u l t s than the f i r s t year data alone. The e a r l y seeding dates, f o r example, could be found t o be u n s a t i s f a c t o r y due t o more r a p i d d e c l i n e in seed y i e l d due t o "sod-binding". The optimum date of seeding of bromegrass a t Beaverlodge appears to be d i f f e r e n t from the optimum date in other l o c a t i o n s . Under c o n d i t i o n s of long growing season and i r r i g a t i o n a t P r o s s e r , Washington Van Keuren and Canode (1963) found f a l l seeding of bromegrass p r e f e r a b l e t o s p r i n g seed-ing. On the other hand, Klebesadel (1970) found t h a t under n a t u r a l f i e l d c o n d i t i o n s a t Palmer, A l a s k a , bromegrass should be seeded before the end of May. The k i l l i n g f r o s t - f r e e p eriod a t Beaverlodge i s about 10 days longer than at Palmer (Guitard e t a l . 1965). The longer growing period a t Beaverlodge a l l o w s l a t e r seeding of bromegrass. There was l i t t l e d i f f e r e n c e in the amounts of heading of C a r l t o n and Redpatch in the year of seeding (Table 4 and 5 ) . In both there was no a p p r e c i a b l e heading f o r seeding dates a f t e r May 28, 1971 o r June 20, 1972. The amount of heading in the establishment year was c o n s i d e r a b l y l e s s than the 89 percent reported by E l l i o t t (1966). C a r l t o n and Redpatch seeded on May 9, 1972 s t a r t e d heading by J u l y 18, and flowered by August 28 (Table 5 ) . This represents a time of 72 days from seeding t o heading. The time i n t e r v a l from p l a n t i n g t o head-ing was 78 days f o r C a r l t o n and Redpatch seeded on May 23. For the June 20 seeding date, the p l a n t i n g t o heading time was 69 days f o r C a r l t o n and 82 38 days f o r Redpatch. The average length of the i n t e r v a l from p l a n t i n g t o heading was 73 days f o r C a r l t o n and 78 days f o r Redpatch. E l l i o t t (1966) reported t h a t i t took 91 days from p l a n t i n g t o heading of C a r l t o n bromegrass grown under 18 hour photoperiod and 70°F temperature in the greenhouse. The c i v i l daylength ranges from a low of 15.2 hours on September 1 t o a high of 19.4 hours in June at Beaverlodge. Mean monthly temperatures over the May t o September period of 1972 d i d not exceed 60°F. The f i e l d c o n d i t i o n s encountered during 1972 shortened the p l a n t i n g t o heading i n t e r v a l by 9 t o 22 days. C a r l t o n and Redpatch seeded on May 9 flowered by August 28 (Table 5). The time lapse between heading and a n t h e s i s was 41 days. This i s c o n s i d e r a b l y longer than the 29 day heading t o a n t h e s i s i n t e r v a l f o r C a r l t o n and Redpatch in the s p r i n g of 1972 (Table 3 ) . The length of the seeding t o a n t h e s i s time i n t e r v a l precludes the production of any seed in the establishment year a t Beaverlodge. III. Insect Damage The damage observed in the i n f e s t e d t i l l e r s v a r i e d in s e v e r i t y (Table 7 ) . In g e n e r a l , e n t r y was made in the area j u s t above the a p i c a l meristem. The larvae worked t h e i r way to the centre of the stem, and then proceeded downward toward the meristem in s p i r a l f a s h i o n . Leaf i n i t i a l s surrounding the meristem were damaged, and l a t e r the a p i c a l meristem was damaged. H e a v i l y damaged t i l l e r s were o f t e n almost completely severed. Rot-causing pathogens g e n e r a l l y invaded h e a v i l y damaged t i l l e r s , c o n t r i b u t -ing f u r t h e r t o the damage. D e t a i l e d records of the areas and extent of damage were kept in the f a l l of 1971 and during s p r i n g and f a l l of 1972 (Table 7 ) . Although Table 7. Damage t o Bromus inermis and B. pumpellianus by i n s e c t l a r v a e . Time Species, Total No. Area of Damage No. % of t o t a l P e r i o d v a r i e t y / e c o t y p e t i 1 l e r s Above Around Meri stem t i 1 l e r s t i 1 l e r s c o l l e c t e d meristem meristem destroyed damaged c o l l e c t e d Fa M Bromus inermis 1971 var. C a r l t o n 241 39 4 14 57 24 Redpatch 251 36 2 4 44 18 B. pumpellianus 54°35' 35 6 - - 6 17 56°35' 33 1 - - 1 3 60°46' 37 2 1 - 3 8 Spring B. inermis 1972 Carl ton 418 18 11 14 43 10 Redpatch 409 19 15 20 54 13 B. pumpellianus 54°35' 16 - - - 0 0 56°35' 17 - 1 - 1 6 60°461 45 2 1 1 4 9 Fal 1 B. inermis 1972 Carl ton 146 3 2 1 6 4 Redpatch 145 - t 1 2 1 B. pumpellianus 54°35' 27 1 - - 1 4 56°35» 28 2 - - 2 7 60°46' 29 — — — - 0 vO 40 d e t a i l e d records were not kept in the s p r i n g of 1971, larvae and l a r v a l damage were encountered. Over the period during which records of damage were kept, damage t o C a r l t o n and Redpatch was heavi e s t in the f a l l of 1971, decreased by the s p r i n g of 1972, and was very low by the f a l l of 1972. Damage t o the three Bromus pumpellianus accessions remained somewhat consta n t , w i t h the exception of the accession from 54° 35', which decreased from )7% damaged in the f a l l of 1971 t o 0 in the s p r i n g of 1972. The i n s e c t s reared from sod samples sent t o Ottawa were i d e n t i -f i e d as four species of C h l o r o p i d and as Uylemya ( D e l i a ) extremitata Mai loch. The Ch l o r o p i d s tended t o i n h a b i t the outer leaves, while the Uylemya were found in the centr e s of the t i l l e r s . On the b a s i s of the o b s e r v a t i o n of the damaged meristems and the l o c a t i o n s in the t i l l e r s in which the larvae were found, i t would appear t h a t the Uylemya was r e s p o n s i b l e f o r the damage. Other Uylemya s p e c i e s are the onion maggot, western wheat stem maggot, the seed corn maggot and the cabbage maggot ( E s s i g , 1926; F r o s t , 1959). 41 SUMMARY Development of f l o r a l primordia of the northern and southern climatypes of Bromus inermis, represented by the v a r i e t i e s C a r l t o n and Redpatch, proceeded in a s i m i l a r manner at Beaverlodge. Both underwent i n i t i a t i o n in the s p r i n g . Development s t a r t e d a t the same time f o r both v a r i e t i e s , and the r a t e of development was very comparable. I t was suggested t h a t temperature i s the major f a c t o r determining the f l o r a l i n i t i a t i o n time of B. inermis in the s p r i n g . The lower seed y i e l d of Redpatch bromegrass could not be a t t r i b u t e d t o d i f f e r e n c e s in time o r degree of f l o r a l i n i t i a t i o n , o r t o d i f f e r e n c e s in response t o seeding dates. I t i s p o s s i b l e t h a t the lower seed y i e l d of Redpatch i s due t o other f a c t o r s in the ex t e r n a l environment, o r due t o inherent low seed y i e l d p o t e n t i a I . The three B. pumpellianus accessions underwent f l o r a l i n i t i a t i o n p r i o r to freeze-up in the f a l l . There was some v a r i a b i l i t y in the time of i n i t i a t i o n , but t h i s could not be r e l a t e d t o c l i m a t i c f a c t o r s a t the c o l l e c t i o n s i t e s . I t i s probable t h a t photoperiod i s the prime f a c t o r governing the f a l l i n i t i a t i o n of B. pumpellianus. P o l a r bromegrass, which has both B. pumpellianus and B. inermis a n c e s t r y , was a l s o found t o undergo f l o r a l i n i t i a t i o n in the f a l l , although o n l y very l i m i t e d sampling was c a r r i e d out. The d i s s e c t i o n of t i l l e r s t o determine the stage of development of the a p i c a l meristem could be useful f o r p r e d i c t i n g whether o r not seed w i l l be produced. In the case of grasses which undergo i n i t i a t i o n in the f a l l , such information could be useful f o r determining subsequent management of the stand. In s p r i n g i n i t i a t e d g r a s ses, d i s s e c t i o n could provide some advance warning of heading. The information gained by d i s s e c t i o n t o inspect 42 the apex i s i n s u f f i c i e n t t o a c c u r a t e l y p r e d i c t the amount of seed t h a t w i l l be produced. On the b a s i s of the l i m i t e d data a v a i l a b l e on seeding dates, i t appears t h a t both of the B. inermis v a r i e t i e s s t u d i e d should be seeded a f t e r mid-May but before mid-July a t Beaverlodge. There are probably season-al d i f f e r e n c e s in both p r e c i p i t a t i o n and temperature which would a f f e c t the response t o seeding date. Damage t o f l o r a l primordia by Hylemya larvae could be of economic importance in some years. There appears t o be seasonal v a r i a b i l i t y in the l a r v a l p o p u l a t i o n . Further study i s warranted t o determine the actu a l extent of the l a r v a l i n f e s t a t i o n in commercial bromegrass crops. 43 LITERATURE CITED 1. ANDERSEN, SIGURD. 1952. Methods f o r determining stages of development in b a r l e y and o a t s . P h y s i o l o g i a Plantarum 5:199-210. 2. BARNARD, C. (ed.) 1964. Grasses and Grasslands (p. 64-67). Macmillan and Co. L t d . , London. 3. BOMMER, D. 1959. Uber Zeitpunkt und Verlauf der B l u t e n d i f f e r e n z i e r u n a bei perennierenden Grasern. Z. F. Acker- u. Pflanzenbau 102: 95-118. 4. BROUE, P. and S. KAWANABE. 1967. 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P o l a r brome-grass - A new winterhardy forage f o r A l a s k a . U n i v e r s i t y of A l a s k a . A g r i c u l t u r a l Experiment S t a t i o n , C i r c u l a r 26. 

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