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Association of economic characters in rhizoma alfalfa 1943

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ASSOCIATION of ECONOMIC. CHARACTERS 33T RHIZOMA ALFALFA A Thesis Submitted 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 the Degree of Master of Science i n A g r i c u l t u r e i n the Department of Agronomy* by Catherine J . Eek The U n i v e r s i t y of B r i t i s h Columbia A p r i l 1943 ACKNOWLEDGMENT Gra t e f u l acknowledgment I f here made to Dr. V. G. Brink5 Dr. G. G. Moe, and Dr. A. H. Hutchinson, under whose guidance t h i s paper was w r i t t e n * TABLE OF CONTENTS Page INTRODUCTION 1 REVIEW OF LITERATURE 6 MATERIALS AND METHODS 10 ASSOCIATION OF SEED 'YIELD JnD OTHER CHARACTERS 12 1» A s s o c i a t i o n of Pod Shape and Number of Seeds 12 Per P6d • " 12 13 14 (a) S e l f p o l l i n a t e d a l f a l f a (b) Open p o l l i n a t e d a l f a l f a •  (g,)* _ Seed set i n grams 2. A s s o c i a t i o n of Flower Abundance and Number of Seeds 16 3. Seed S e t t i n g Compared i n Racemes Which Have Been S e l f e d and Open P o l l i n a t e d - 17 4. A s s o c i a t i o n of Flower Color and Seed Y i e l d 20 5. Comparison of Seed Y i e l d f o r Two Successive Years 22 6» D i s t r i b u t i o n of Seed Y i e l d Classes 22 7. Comparison of Seed Y i e l d , P l a n t Heights and 24 Plant Weights i n F i and F 2. 8. Comparison of Seed Y i e l d ' i n Fj_ plants & F 2 Progeny 25 ASSOCIATION OF FACTORS NOT INVOLVING SEED YIELD 27 1. Comparison of Height and.Weight Between F^ & F 2 27 ,2. A s s o c i a t i o n of Y i e l d and Height 29 3. A s s o c i a t i o n of Leaf Spotting Incidence and the Percentage of Ovules Developing on the Racemes. 30 4. A s s o c i a t i o n of Leaf Spotting and Leaf Color 31 5. A s s o c i a t i o n of Leaf Spotting and Flower Abundance 32 6. A s s o c i a t i o n of Stem Thickness and Plant Height 32 7. A s s o c i a t i o n of Height and Spread 33 Page 8 A s s o c i a t i o n of Flower Abundance and Raceme Supportin Ovules 35 9 As s o c i a t i o n of Foliage Colour and Flower Abundance 36 10 A s s o c i a t i o n of Flower Abundance andFlower F a l l 37 FLOWER COLOR INHERITANCE 38 DISCUSSION 41 CONCLUSIONS 43 SUMMARY • " 45 1 ASSOCIATION' CO? ECONOMIC CHARACTERS IN RHIZOMA ALFALFA •' > ;, A l f a l f a j to-days i s one of the world's leading forage crops, I n the regions favoring i t s grovvth, a,nd these are now many,, no crop.used f o r fodder surpasses i t i n general u t i l i t y and y i e l d . For thousands of years a l f a l f a was h i g h l y regarded i n south-western A s i a , i n which area i t was endemic, as forage sine qua hon. Slowly, s e l e c t e d . s t r a i n s made t h e i r way_into the a g r i - c u l t u r a l regions of North A f r i c a , , and southern Europe u n t i l "by the end of the' 19th century a l l of tempera-te -~; E u r a s i a knew i t as a valuahle a d d i t i o n to the forage resources. The value of the crop •was recognized "by the ea r l y white s e t t l e r s i n the Y/estern .hemisphere and, undoubtedly i n many separate occasions the plant was introduced to the new a g r i c u l t u r a l area. However, p r i o r to 1900 i t i s doubtful i f the t o t a l acreage i n "both western continents, exceeded 3 m i l l i o n "acres. Since^that':, date a t r u l y phenomenal expansion i n acreage has taken place e s p e c i a l l y i n the United States, the Argentine, Uraguay, Paraguay, Mexico and i n A u s t r a l i a , In the U.S.A. alone present crop acreage must ..now exceed 20 m i l l i o n acres. . . • C.anada has not "been excluded i n the "march" of a l f a l f a over the glohe. With the development of winter hardy s t r a i n s f o r cooler and more humid areas a l f a l f a acreage spread i n Canada. Ontario, B r i t i s h Columbia and the p r a i r i e provinces now maintain a combined crop area of ij? m i l l i o n acres. In B r i t i s h 'Columbia/ a l f a l f a has become the standard hay and pasture crop i n the c a t t l e ranching and i r r i g a t e d d i s t r i c t s . A l f a l f a , u n l i k e many other forage crops which posses, a few commendable c h a r a c t e r i s t i c s , has to i t s c r e d i t many desir a b l e agronomic features. I t i s t h i s combination or blending of so many desir a b l e agronomic features which account f o r I t s popularity.. A l f a l f a i s a legume and as such i s a.well known source of p l a n t p r o t e i n and a-'highly regarded s o i l enricher. Few crops produce p r o t e i n so e f f i c i e n t l y } from three tons of . a l f a l f a hay (an average crop) 625 pounds of digestable p r o t e i n are obtained' A comparable crop of timothy (1.5 Tons) produces by compai-ison only 90 pounds of digestable p r o t e i n ; a crop of clover . (3 Tkns) , 40Q pounds and a barley crop (50 B u s h e l s ) 5 200 pounds. In common w i t h most legumes, . a l f a l f a w i t h associated FJraobia, f i x e s appreciable q u a n t i t i e s of atmospheric nitrogen and as such plays an important p a r t i n main- t a i n i n g the s o i l n itrogen balance on the farm. The significa,nce of t h i s at the present time i s w e l l por- . trayed by Wilson i n a recent p u b l i c a t i o n . . . . A l f a l f a has a f u r t h e r marked advantage as a forage crop i n that i t i s a perennial and agressive. Once .•established a stand competes e f f e c t i v e l y w i t h weeds and i n most l o c a l i t i e s w i l l maintain i t s e l f w i t h l i t t l e or no care f o r at l e a s t 6 - 7 years. Then again the deep ro o t i n g h a b i t of many s t r a i n s of lucerne has established the crop as a drought t o l e r a n t species. As such i t i s . w e l l known i n the subhumid and a r i d regions of t h i s continent. Recent s e l e c t i o n s of winter hardy s t r a i n s have f u r t h e r advanced i t s reputation as a crop f o r cold dry climates of the north and f a r south. Although the .desirable agronomic features of a l f a l f a f a r outweigh . the undesirable, the crop ..has. c e r t a i n l i m i t a t i o n s which cause the p l a n t breeder concern. For one things the 'plant, as we know i t i n commerce Is a n o t o r i o u s l y poor seed s e t t e r . Seed* as a consequence i s h i g h p r i c e d . In recent years:, too, a t t e n t i o n has been drawn to the increasing.importance of :crown i n j u r y i n standard s t r a i n s and the f a i l u r e of i n j u r e d plants to overcome attacks from i n s e r t s and fungus pests. Then, again coincident, w i t h the expansion of a l f a l f a , acreage i n the world, has come a growing r e a l i z a t i o n of the handicaps i n producti©£l r e s u l t i n g from such diseases as w i l t , l e a f s p o t and v i r u s . The a t t e n t i o n of_the p l a n t breeders,then has been . a t t r a c t e d by the r e c o g n i t i o n of these imperfections and already many programs f o r a l f a l f a Improvement have been undertaken. One of the e a r l i e s t consibus attempts at a l f a l f a • improvement-' through "breeding and s e l e c t i o n has much of i t s ' h i s t o r y l a i d at the U n i v e r s i t y of B r i t i s h Columbia from 1918 onwards. The early objects"of the program was to produce through i n t e r s p e c i f i c h y b r i d i z a t i o n a s t r a i n of a l f a l f a w i t h a crown and root system s u i t a b l e f o r subhumid conditions when a r e l a t i v e l y h i g h water table p r e v a i l e d over much of 'the year. The e a r l y work.on t h i s p r o j e c t has been adequately reviewed by Hoe (23) and only, a, b r i e f reference w i l l be .made'' to i t . With the growing importance of a l f a l f a i n the a g r i c u l t u r a l economy and a 'deeper: r e a l i z a t i o n of i t s problems., i t i s i n conformity that the a l f a l f a improvement programme should change, should broaden i n I t s scope and purpose.'. F i e l d records, some complete, some incomplete,, are a v a i l a b l e i n the programme f o r some twenty years of i t s - h i s t o r y . Therefore i t seemed appropriate at t h i s time to survey these records i n the l i g h t of present knowledge. In a d d i t i o n some records -taken by the author on the l o c a l m a t e r i a l i n the summer of 1941-42 and 1942-43 were studied. P r i n c i p a l l y the report i s a study of- the a s s o c i a t i o n of economic characters i n the a l f a l f a grown at the U n i v e r s i t y of B r i t i s h Columbia. Charactei-s vvere chosen such as seed weight, seed number, pla n t height and the l i k e and t h e i r a s s o c i a t i o n w i t h general c h a r a c t e r i s t i c s such as seed s e t t i n g , p l a n t y i e l d and crown c h a r a c t e r i s t i e s s c r u t i n i z e d . For plant breeding i s not the simple s e l e c t i o n of d e s i r a b l e c h a r a c t e r i s t i c s and the mere i n c o r p o r a t i o n of these i n a s i n g l e desirable s t r a i n . I t i s a study i n i n t e r a c t i o n and li n k a g e , complex to a high degree? the combination of features of merit must i n t i m a t e l y be represented i n many s t r a i n s and not i n one aiohe and the procedure used i n accomplishing t h i s are at once both an a r t and a science. How successful t h i s study i n a s s o c i a t i o n has been, w i l l be f o r the reader to decide; d i f f i c u l t i e s such as incomplete records, poor seed s e t t i n g and the l i k e , hare upset the study from time to time. I t i s hoped however that something has been added to our knowledge of the behaviour of economic characters i n the i n t e r s p e c i f i c h y b r i d a l f a l f a such as that at the U n i v e r s i t y of B r i t i s h Columbia. REVIEW OE LITERATURE At present .the most important problem as f a r as a l f a l f a i s concerned i s the improvement of i t s seed set 7. A large amount of work on t h i s problem has de a l t w i t h the e f f e c t of t r i p p i n g on seed set. Tripping can be brought about by weather, Insects or a r t i f i c i a l means. O f a l l there i n s e c t s studies Megachile species have been found the most s a t i s f a c t o r y . Lejeune and Olson (19) found that honeybees brought about very l i t t l e t r i p p i n g . Hay (13) found that the l a c k of s u i t a b l e i n s e c t s and •unfavourable weather conditions f o r t r i p p i n g contributed to the low seed y i e l d . Clark and Eryer ( 7 ) , Carlson ("6). and Bouthworth (5) conclude that t r i p p i n g increases seed y i e l d . K i r k (17) has developed a s e l f t r i p p i n g (autogamous) a l f a l f a which gives promise of overcoming t h i s d i f f i c u l t y . Various studies have been done on h y b r i d i z a t i o n s as a means to in c r e a s i n g seed y i e l d . Dwyer selected high y i e l d i n g s t r a i n s by inbreeding, then crossed them to regain v i g o r . Englebert (10) found that the seed y i e l d of any s i n g l e hybrid v a r i e d w i t h the environmental conditions. A number of papers have been w r i t t e n on the development of an inbred strain-which w i l l give &, good seed y i e l d K i r k (16) found that.seed y i e l d was•inherited to a c e r t a i n degree. Tysdai and Clark (29), Bolton and Eryer (2) and Southworth (25) found that the general seed y i e l d went down on inbreeding but a few high y i e l d i n g p l a n t s segregated which "bred true f o r t h i s q u a l i t y . S e l f s t e r i l i t y i n a l f a l f a has given r i s e to many studies. B r i n k and Cooper (3) found that there were fewer f e r t i l e ovules i n s e l f e d m a t e r i a l and that the lower ovules were r a r e l y f e r t i l e . Bolton and Fryer (2) working on p o l l e n s t e r i l i t y d ivided i t i n t o two classes: (a) c l e a r empty grains,- (b) normal appearing which d i d not germinate. Brink and Cooper (3)- found a f a i l u r e of f e r t i l i z a t i o n even a f t e r t r i p p i n g . P o l l e n tubes.'were produced and i n some cases f e r t i l e ovules starte d to develop but f a i l e d to mature. The embryos of low seed y i e l d e r s developed more slowly and there was .a'-large percentage of.abor^fesMU ovules. Brink and Cooper (3)' found that f e r t i l i z a t i o n was prevented due to abnormal p o s i t i o n a l r e l a t i o n s h i p between anthers and' stigma. The part of•enviromental e f f e c t must not be overlooked i n relation-; to seed set. Bolton and Fryer (2) found that . s o i l moisture and the .stage.of the seasonal development contributed a great deal to seed set. They found that the normal appearing p o l l e n , mentioned above, would germinate under favorable c l i m a t i c conditions. Preeman (11) cautions that h e r e d i t a r y f a c t o r s can only show up to advantage- i n a s u i t a b l e environment. .-Tysdal and Clark (7) emphasize the e f f e c t of temperature and l i g h t on seed production. • Southworth (25) stresses the e f f e c t of moisture, he con- cludes that there should be s u f f i c i e n t moisture to f i l l the seed a f t e r i t has set but i n the e a r l y stages of 8 development abundant moisture w i l l stimulate the develop- ment of leaves and height at the expense of seed; set. Englebert (10) substantiates Southworth's work $ fi n d i n g , that seed set was better i n years when there was a l i m i t e d r a i n f a l l i n J u l y and poor when there was excessive r a i n f a l l f o r t h i s month. H y b r i d i z a t i o n has been used as another method o f improving a l f a l f a . Among the c h a r a c t e r i s t i c s which have been given s p e c i a l emphasis are disease r e s i s t a n c e , root types, winter h a r d i n e s s s e e d y i e l d and weight of p l a n t s . The cytology of these hybrids has .yielded a great deal •of information of i n t e r e s t g e n e t i c a l l y . The cross i n a l l cases was only successful i f H. f a l a c a t a was used as the p i s t i l l a t e parent. I)wyer (9) found that a cross between M. s a t i v a and M. Lupulina gave a poor forage y i e l d . Southworth (23) i n t r y i n g to develop a s e l f t r i p p i n g v a r i e t y used Iffi. l u p i l i n a , as the p i s t i l l a t e parent because of i t s s e l f g r i p p i n g c h a r a c t e r i s t i c s . The F l and E2 gave a great v a r i e t y of types but a very poor seed y i e l d . I n the E3 a few good _seed producing pl a n t s appear,. A few, s e l f t r i p p i n g v a r i e t i e s appeared i n the E4 but were not s e l f f e r t i l e . I t was not u n t i l the 3?6 that one s e l f t r i p p i n g ^ s e l f f e r t i l e p l a n t appeared. The flower color i n these i n t e r s p e c i f i c cross has provoked considerable i n t e r e s t . ' The Iff., f a l a c a t a i s pure breeding yellow and the M. s a t i v a blue. - The E l and , succeeding generations give a wide v a r i e t y of color from white to yellow and deep purples. Burton (5) found that flower color had no p o s i t i v e c o r r e l a t i o n s with any of a number of other c h a r a c t e r i s t i c s . Hay (13) found that color had no e f f e c t on seed set, while Moe(23) on the other hand suggested that white flowered plants v/ere poor seed y i e l d e r s . Lepper and Odland (20) conclude that flower color i n a l f a l f a was due to three f a c t o r s . •'During the many breeding experiments i n v o l v i n g a l f a l f a , a number of abnormal t i e s have come to l i g h t . Lepper and Odland (19) mention a c r i n k l y . l e a f mutation. Stewart (24) mentions a p e c u l i a r v e g i t a t i v e p r o l i f e r a t i o n , which replaces the a l f a l f a flowers. MeVicar (22) found white seeds were due to a homozygous recessive f a c t o r as a r e s u l t of the absence of a f a c t o r f o r yellow. Black seed required at l e a s t three f a c t o r p a i r s and arose o r i g i n a l l y as a s i n g l e gene mutation. This only very s u p e r f i c i a l l y touches on a few of the l i n e s of i n v e s t i g a t i o n being c a r r i e d on w i t h a l f a l f a . Winter hardiness and disease r e s i s t a n c e are problems which are r e c e i v i n g a great deal.; of a t t e n t i o n i n other parts of the continent. In t h i s vast improvement Work w i t h a l f a l f a many in t e r e s t i n g ' f a c t s are being brought to l i g h t which are c o n t r i b u t i n g g r e a t l y to the improvement -of. a l f a l f a , and p l a n t improvement work i n general. 10 MATERIALS AED METHODS. The materials used i n these studies were the h i g h l y heterozygous population which r e s u l t e d from s i x hybrids of a cross M. f a l a c a t a ( $ ) X M. s a t i v a ( <jp ) . D e t a i l s of the h y b r i d i z a t i o n and subsequent treatment of the progeny are given by Moe (23). "A few of the more important features of t h i s plant m a t e r i a l might be b r i e f l y emphasized. I t should be noted that t h e ' p i s t i l l a t e parent-.in the cross was u s u a l l y the low growing yellow flowered ffi. f a l a c a t a Yar. Don. and that the p o l l e n parent was a t a l l purple flowered v a r i e t y of Grimm one of the Ontario "Variegated type. Seed obtained from the hybrids was grown out and s i x t a l l growing hybrids' were d i f f e r e n t i a t e d from the low growing hybrids. , The hybrids proved to be considerably f e r t i l e and produced some seed i n good seed years both from s e l f e d and open p o l l i n a t e d racemes. . The flower color of the hybrids was variegated but showed a preponderance of yellow pigment. The hybrids were s e l f e d and the seed thus produced was subjected to progeny -row t e s t s . The seed was then taken from these, selected p l a n t s -and- i t s e l f set out i n progeny rows. At t h i s time l i t t l e or no attempt was made to c o n t r o l p o l l i n a t i o n but there was no opportunity f o r admixture of p o l l e n from other s t r a i n s or v a r i e t i e s . The progeny from the F2 and subsequent generations 11 showed an enormous degree of segregation. Many of the selected p l a n t s showed a great v a r i a t i o n as to type of growth, vigor and degree of s t e r i l i t y . ; . Careful s e l e c t i o n of i n d i v i d u a l plant progeny was c a r r i e d on f o r f i v e generations "but at the end of that time there was s t i l l a high degree of segregation; I.e. no s t a b i l i t y of type had, as yet "been established. From the F2 arid succeeding generations the pppulations Yirere the subject of a mass s e l e c t i o n program. In' t h i s work emphasis was placed, on seeking a higher y i e l d i n g a l f a l f a with,the spread c h a r a c t e r i s t i c s of the M. f a l a c a t a parent and the q u a l i t y c h a r a c t e r i s t i c s of the M. s a t i v a . Records were taken by the Department of Agronony on many morpholigical c h a r a c t e r i s t i c s of both the hybrids arid p l a n t s of. subsequent generations. From these records • data on spread, height, seed y i e l d , pod shape and flower color were used. During the summer of 1941 plan t s were selected at f - random from the f i f t h generation m a t e r i a l and Roger's a l f a l f a . ' From there p l a n t s data on pod slaape, number of seeds per pod, seed set, f o l i a g e c o l o r , flower c o l o r , flower f a l l , stem thickness, plant height and degree of l e a f s p o t t i n g , were taken. The f o l l o w i n g s t a t i s t i c a l a n a l y s i s was used as the best method of organizing and i n t e r p r e t i n g t h i s data. EXPERIMENTAL WORK I As s o c i a t i o n of Pod Shape and Number of Seeds Per Pod, (a) S e l f p o l l i n a t e d a l f a l f a It,was thought there might be some a s s o c i a t i o n between the seed y e i l d and the s i z e of the pod, i . e . the number of tw i s t s i n i t . Cooper and Brink (3) have found that s t r a i n s which produce a large number of seeds continue to do so and s t r a i n s g i v i n g a small amount of seed tend to continue t h i s low seed y e i l d i n future generations. Bo^toE* and Fryer (2) are of the opinion that the number of seeds per pod i s a better index of inherent f e r t i l i t y than the percentage of flowers which give r i s e to f u l l y developed pods* They also s t a t e t h a t seed s e t i s due to genetic f a c t o r s and the number of seeds per pod i s a good i n d i c a t i o n of t h i s inherent capacity, A good seed s e t t i n g s t r a i n w i l l tend to continue t h i s abundant seed s e t t i n g cap- a c i t y , even of s e l f i n g . Table I gives the d i s t r i b u t i o n of the number oj seeds per pod against the number of t w i s t s per pod. The number dh brackets i n each case i s the expected number the number above the the a c t u a l number, The number of t w i s t s per pod were d i v i d e d i n t o three catagories curved ( s e m i - c i r c l e ) , one c i r c l e , and more than one c i r c l e . The number of seeds per pod were also d i v i d e d i n t o three ca t e g o r i e s , 2, 4, and 6 seeds per pod; M a t e r i a l used f o r t h i s study was data taken by the author from Rogers (24) a l f a l f a . The t o t a l number of samples taken here i s fifty-nine<> A la r g e r number might y e i l d somewhat d i f f e r e n t r e s u l t s . The c h i square f o r 4 degrees of freedom at the 1% l e v e l i s only;13.28| the c h i square f o r expectation i s 28.10. In- dependence i s therefore u n l i k e l y and a strong a s s o c i a t i o n of h i g h l y - c u r l e d seeds and a large number of seeds per pod i s l i k e l y . Table I 1- 1. a 2 i 6 T o t a l lvL • - 16 (9.4) 7 (9.1) i- 0 . i (3.5) 1 t 23 b 8 (9.4) 14 (9.1) 1 (3.5) 1 1 23 c 0 (5.3) •''/ 5 / (5.8) 8 (2.9) : 13 To t a l ; 24 •: 26 9 / . 59 a — curved b — one c i r c l e c — more than one c i r c l e . •, (b) Open p o l l i n a t e d This study i s the same as the previous one i n a l l respects except t h a t the m a t e r i a l was open p o l l i n a t e d instead of s e l f e d . Table 2"gives the d i s t r i b u t i o n of the seeds and the shape of•the pods. The' categories are the same as Table 1. Table 2 2 4 . e Total a 9 (2*5) 2 (4.3) 0 (2.5) 11 b 3 (2.6) 16 (7.5) 0 (7.1) ! 19 c 0 (5.3) 3 (7.1) 20 (8.6) T o t a l 12 21 20 • 53 The c h i square f o r 4 degrees of freedom at the 1% l e v e l of s i g n i f i c e n c e i s 13.28 which shows an a s s o c i a t i o n between the the number of seeds per pods and the number of t w i s t s per pod. K i r k (17) found that the seed y i e l d upon open p o l l i n a t i o n was greater than upon s e l f i n g but high y e i l d i n g s t r a i n s tended to remain good seed producers whether open or s e l f e d . As i n the previous case the number of samples are s m a l l , making these r e s u l t s f a r from conclusive,, (c) Seed set i n grams Larger number were a v a i l a b l e f o r t h i s study. There were 26 progeny rows (open p o l l i n a t e d ) from a l l of the hybrids (1928), g i v i n g a t o t a l of 770 p l a n t s . Table 3 gives the d i s t r i b u t i o n of seed y i e l d i n grams com- pared w i t h the shape of the pod. The categories have been en- larged i n both cases. Table 3 15 Table 3 Seed -weight i n ' grams Ho.of t w i s t s 0-2 1 2-4 |4-6' 6-8 i i 18-10 10-12 total 12 (7.7) 1 (.4) 1 13 144' ! ,110.3) '< - „ / 22 (25.9) 8 (4.4) 4 (9.8) 1 (6.4) 2 (6.2) 4 "T (12;. " . • 190 199,8) 52 (47.1) 25 (24.8) 18 (17.9) 14 (11.?:) 13' (11.3) 24 . (23.1) 336 1-|~2 98 116.5) 30 (27.5) 17 :(14.5) 14 (10.4) 10 (6.8) 8 (6.6) 19 : (13,5) 196 14 23.7) 4 (5.1) 7 (2.9) 5 (2.1) -'"1. '- (1,4) ; 3 (1.1) 6 (2.7) 40 T o t a l 458 1 108 57 41 27 26 53 770 The number of t w i s t s bears no s t a t i s t i c a l r e l a t i o n to the weight of seed set per p l a n t . This however does not imply that there i s no c o r r e l a t i o n between the number of t w i s t s per pod and the number or weight of seed set per pod. In t a b l e 4 the categories have been reduced to 3 f o r y i e l d and 3 f o r number of t w i s t s per pod. 16 Table 4 1 1 1 JTo. of t w i s t s Amount of Seed Set (Grams) Total 8 1 | . 0 - 1 l , • 0 .- 4 4 -8 • 8 - 14 178 (145.5) 12 (25.2) 8 (27.25) 198 1 1 - 2 1 370 (391) 74 (67.7) 88 (73.23) 532 1 2 - 3 18 (29.4) 12 (5.09) 10 (5.5) 40 T o t a l 566 98 106 770 The c h i square f o r 4 degrees: of freedom at the 1% l e v e l of p r o b a b i l i t y is' 13 0 28. One might conclude that there i s a s i g n i f i c a n t a s s o c i a t i o n between low y i e l d of seed and the s m a l l amount of t w i s t i n g i n the pod. In t h i s connection Brink and Cooper (3) found that the lower ovules i n the c a r p e l d i d not develop into mature seeds due to (a) f a i l u r e o f . f e r t i l i z a t i o n (b) ovule abortion or (c) i n f e r t i l i t y of the ovule. 2. A s s o c i a t i o n of Flower Abundance and Number of Seeds The F^ plants d i f f e r e d g r e a t l y i n the number of flowers produced. A c h i square was run on t h i s c h a r a c t e r i s t i c to see i f i t had any bearing on the seed y i e l d . The flower abundance was put i n 3 categories, poor, f a i r and good. The i n d i v i d a u l seeds produced were counted and d i v i d e d i n t o 3 categories 0 - 3 0 , 30 - 60, 60 and more. Table 5 gives the d i s t r i b u t i o n . 17 Table 5 Flower Abundance Number of Seeds 0 - 3 0 30 -SO "1 : j- 60 + Total Poor 10 (7.9) 1 • 1. s ; (4.8) 1 (3.2) 16 F a i r i 14 . (13.3) ! 11 (8.2) 2 (5.4) 27 Good 10 (12.8) •(7.9) 11 C5*5) | 26 . - T o t a l 34 21 14, 69 The c h i square at the 5% l e v e l of p r o b a b i l i t y and 4 degrees of freedom i s 9.49. An a s s o c i a t i o n i s i n d i c a t e d , however, data are too few to place much confidence i n these r e s u l t s . A d d i t i o n a l work using l a r g e r numbers might y i e l d d i f f e r e n t r e s u l t s . Bolton and Fryer (2) are 6f the opinion that flower abundance i s no i n d i c a t i o n of seed y i e l d . And Cooper and Brink (3) found that t r i p p i n g increases the number of flowers forming seed. 3. Seed S e t t i n g (expressed as seeds per pod per plant) Com- pared i n Racemes Which Have Been S e l f e d and Open P o l l i n a t e d . Rogers (24) a l f a l f a was used f o r t h i s c o r r e l a t i o n . Plants were s e l e c t e d on the basis of flower colour. S i x colour des- ignations were given, white, paJLe y e l l o w 9 y e l l o w , variegated 18 purple yellow, dark purple, pale purple. Open p o l l i n a t e d racemes were tagged, while s e l f p o l l i n a t e d ones were r o l l e d i n the f i n g e r s and tagged. Table 6 gives the seed y i e l d per raceme i n number of seeds. There too few seeds to weigh. Table 6 Seed S e t t i n g (expressed as seeds per pod per plan t ) Compared .in-Racemes'-Which Have Been S e l f e d and Open P o l l i n a t e d . PLANT No. Seeds per Raceme (average) No • S e l f e d Open (x) (y) . 1 1 6 2 15 4 1 2 2 3 16 3 5 3 2. • 4 17 4 1 4 3 3 18 3 1 5 4 '• 4 ; 19 2 2 6 i • q 4 20 2 2 7 2 2 21 5 5 8 4 3 " .* 22. : '5 3 9 6 •" • 8 23 7 3 10 4 2 24 9 • 2 - 11 3 3 25 7 .• 12 ; 4' A 3 26 6 ® 13 4 3 27 3 1 14 i 6 j 28 6 , 3 19 29 " . 4 4 43 2 4 30 4 ' 4 44 6 6 31 4 4 45 2 2 4 2 46 5 2 33 6 V 2 47 4 4 34 5 5 48 1 2 35 6 2 \'-: 49 4 36 2 '."2; • 50 4 ' 3 37 : 4 :. 4 : 51 6 5 38 5 6 52 '4 2 39 3 2 53 2 2 40 4 3 54 6 3 41 6 2 55 5 4 42 •5. — 1 > One may s a f e l y conclude t h a t the open p o l l i n a t e d racemes set more seed per pod than d i d the s e l f p o l l i n a t e d racemes. The d i f f e r e n c e , however, i s not" large and would i n d i c a t e that the degree of s e l f s t e r i l i t y In the F5 plants used i s not high. S e l f i n c o m p a t a b i l i t y f a c t o r s e t c e t e r a might be set f o r t h and the influence of tagging andjJaandiiHg might have been d e l e t e r i o u s . AhnormaX p o l l e n Is - as abundant i n the open as i n the . s e l f ed.plant m a t e r i a l . -It 'could not therefore be a reason f o r the lower y i e l d i n the f i r s t case. However, plants which tend to set seed abundantly In the open p o l l i n a t e d m a t e r i a l tand to set seed w e l l i n the s e l f e d . 20 The a s s o c i a t i o n i s not strong b i o l o g i c a l l y although s t a t i s t i c a l l y i t i s h i g h l y s i g n i f i c a n t . I t would seem there~ fore that there i s some evidence to support the i n d i c a t i o n s of s e l f i n c o m p a t a b i l i t y f a c t o r s . Kirk. (17) on comparing s e l f and open p o l l i n a t e d m a t e r i a l found a general decrease i n y i e l d - w i t h s e l f i n g , however, a fewe s t r a i n s segregated which gave c o n s i s t e n t l y good y i e l d . Tysdal and Clark (28) and Cla r k and Fryer (7) substantiates K i r k ' s work. 4. A s s o c i a t i o n of Flower Color and Seed Y i e l d M a t e r i a l s used here were the 1928 records of the F 4 progeny. There were a great many flower c o l o r types e x h i b i t e d i n the f i e l d and i t was thought t h a t the seed y i e l d might be associated with f l o w e r ^ c o l o r . Although there were about 15 d i f f e r e n t c o l o r designations they were e i t h e r predominantly purple or yellow. The flower c o l o r was therefore d i v i d e d into 4 classes on the b a s i s , purple, variegated purple, yellow, and variegated yellow. The seed y i e l d was taken i n grams per plan t and d i v i d e d into 4 categories as shown i n Table 7' Table 7 - F ' . t'Seed s Flower- Color Purple. Var.. Purple Yellow Var. Yellow T o t a l Y i e l d i n grams per plan t 0-1 1-6 6-10 10 - 15 23 •8 29 61 1 29 69 15 12 25 T o t a l 38 52 76 170 21 Many r a t i o s weretried to determine the genetics of flower color inheritance hut none f i t t e d . No doubt these could be. worked out w i t h c o n t r o l l e d p o l l i n a t i o n . Two f a c t o r s (a) f a i l u r e of c o n t r o l l e d p o l l i n a t i o n ( s e l f i n g ) and (b) the prob- a b i l i t y of complex p o l y p l o i d r a t i o s complicated t h i n g s . Lepper and Odland (20) set f o r t h a 3 f a c t o r basis for flower c o l o r inheritance i n a l f a l f a . , They only took t h e i r work to the F p, but had they c a r r i e d t h e i r i n v e s t i g a t i o n s on to the Fg they might have found flower color inheritance more complex, i . e . p o l y p l o i d y was involved* In connection w i t h flower c o l o r an& seed y i e l d , Moe (23) found t h a t white flowered plants tended to give a low seed y i e l d while Hay (14) e?n the other hand, found no a s s o c i a t i o n between flower c o l o r and seed y i e l d . Table 8 gives the d i s t r i b u t i o n of seed y i e l d ( i n grams) and flower color using more c o l o r designations than Table 7. Table 8 Seed y i e l d (Grams per p l a n t ) Flower Color ; o - i 1-6 6-10 10- T o t a l Blue 7 12 5 2 ' 26 Purple 13 15 4 6 38 Variagated 51 59 11 20 141 Green 7 9 • 7 " :; :. 7 30 Yellow 2 2 4 White: . ; 1 1 1 T o t a l 80 98 21 35 240 22 In both Tables 7 and 8 no a s s o c i a t i o n was found between seed y i e l d and flower c o l o r . In the above studies formation of classes f o r flower color w>as d i f f i c u l t due to various f i e l d workers idea of c o l o r . The flowers tended to change co l o r during the blooming period which made an accurate color des- i g n a t i o n d i f f i c u l t . In t h i s connection i t was noted that the darker colors - blues and purples tended to predominate,Whether t h i s i s due to dominance or a greater gene frequency i s un- known* 5, Comparison of Seed Y i e l d f o r Two Successive Years, A comparison of the seed y i e l d of the progeny of the hybrids f o r two d i f f e r e n t years was made. The mean y i e l d f o r the f i r s t year was 1,52 grams and f o r the second ,60 grams. This lower seed y i e l d i s probably due to environmental causes and bears out the work of Hay (14), Bolton & Fryer (2) Freeman (11), Southw#t*F^23) arid Englebert (10) In both years though, good seed y i e l d e r s tend to y i e l d seed w e l l and poor seed y i e l d e r s to give poor seed y i e l d s . This consistancy of seed y i e l d suggests the operation of her e d i t y f a c t o r s , 6, D i s t r i b u t i o n of Seed Y i e l d Classes. The accompanying graph shows the d i s t r i b u t i o n of plants as to seed y i e l d . Plants 38 36 34 \ O CO 01 ~3 CD F-1 <D O O O €> O r d i n a r i l y i t would be expected to f i n d the seed y i e l d f a l l i n g i n a normal d i s t r i b u t i o n curve. This d i s t r i b u t i o n i s h i g h l y skewed, there are d i s t i n c t l y more high y i e l d i n g plants than expected i n a normal d i s t r i b u t i o n . This would seem to i n d i c a t e the operation of h e r e d i t a r y f a c t o r s . 24 7 Comparison of Seed Y i e l d , Plant Heights and Plant Weights i n F]_ and F- ' The materials used f o r t h i s . s t u d y were the o r i g i n a l 7 hybrids and t h e i r F^ and S*2 progeny. The seed y i e l d and plant weight were ..taken i n grams . and the height i n inches. Table 9 gives the seed y i e l d , plant weight, and plant height f o r the,7•hybrids f-also the average seed y i e l d , plant weight and p l a n t height f o r the Fg progeny of the hybrids. Table .9 Designation of Plants Seed Y i e l d (g) Plant Wt. 'Plant (") Ht. • Hybrid -7 • V7.0 172 28 " -56 • .1.4. : 148 24 » -68 0.9 r 123 20 " -71 ; ;0-,3 : ; > 136 23 »' -156 2.4 100 24 " -190 3.5 263 30 F 2 of H-7 1.5 (ave. )tj 92.4(Ave] ••25.4 (ave.) 11 " H-56 1,6 •»»•"/.; 57 © 2 ti 20,3 ii'.. i it ti H _ 6 8 0.8 » L'~ 55,7 it 19.7 it " " H-71 0.4 " •: 24,-9 It • 13,5 \\ 0.8 " -.3 32.7 H ' 14,8 II " "H-190 ••.••,1.7.,; 48.9 11 14.9 H . 1 Kirk- (17) found a reduction of v a r i a b i l i t y i n the F 2 w i t h s e l f i n g . The above f i g u r e s would i n d i c a t e h y b r i d v i g o r . Comparisons of previous tables on seed y i e l d s i n d i c a t e that the seed y i e l d and pl a n t v i g o r are c o r r e l a t e d , I.e. the same f a c t o r s which are responsible f o r low seed y i e l d are i n a l l p r o b a b i l i t y responsible f o r a lessening of v i g o r . From Table 9 can be seen the s t r i k i n g reduction i n height and weight o.f the Fg over the F i but a few plants i n the F gave an increased y i e l d over the F-,, Ct. Throughout there seems to be a small c o r r e l a t i o n i n y i e l d of the Ft and the y i e l d of t h e i r progeny. This may be a s i g - n i f i c a t n observation i n terms of t h e i r chromosome number. 8. Comparison of. Seed Y i e l d i n F. Plants and F2 Progeny (Open p o l l i n a t e d prevaling) The Fj_ here used were the or i g i n a l J T hybrids. T;<. The weight i n each case was taken i n grams. The seed y i e l d of the progeny i s l i s t e d i n 2 columns, the average seed y i e l d and the maximum seed y i e l d . Table 10 gives these seed y i e l d s . . • Table 10 ' "1 Hybrid No. • Hybrid Seed Y i e l d (grams) Progeny Sample Average gms.. per p l a n t Seed Y i e l d Maximum- gms • per p l a n t . # 7 * 7.0 1.5 ,4.7 ; 56 1.4 1 , . • . 1.6 11.5 68 0.9 0.8 6.0 71 0.3 0.4 6.2 , 168 j 2.4 0.8 4,0 • 190 3.5 1.7' ; 7.0 Average 2.56 0.9 6.6 26 The progeny on the average tended to repeat the seed y i e l d i n g a b i l i t i e s of the p a r e n t a l hybrids. -The maximum seed y i e l d e d by any one i n d i v i d u a l i n progeny bears l i t t l e r e l a t i o n s h i p to the c o n s t i t u t i o n of i t s hybrid. The data were too few f o r I f x y but the j f x y — ^".45 which was s i g n i f i c a n t f o r columns a and b. ASSOCIATION' OF FACTORS NOT INVOLVING SEED YIELD. 1. Comparison of Height and Weight Between F ^ and Fg. • Materials used f o r t h i s study were the weights and heights of the hybrids and the average heights and weights of random samplings of t h e i r progeny. Both K i r k ( 1 7 ) , Stewart ( 2 6 ) , Tysdal & Clark ( 2 8 ) and Southworth ( 2 5 ) found a reduction of v a r i a b i l i t y on succeeding generations. Table 1 2 gives the d i s t r i b u t i o n of height and weight f o r the F-̂  and Fg« The lower number f o r the Fg would point to the action of h y b r i d v i g o r . The F]_ c e r t a i n l y gives high f i g u r e s than the parent M. f a l a c a t a p l a n t which i s low gown and low y i e l d i n g . Table 1 2 i n d i c a t e s that the v i g o r of the plants decreases on s e l f i n g , which i s shown by the s t r i k i n g decrease i n height and weight of the F over the Fq_. 28 Table 12A ; Wt. Comparisons j 1 Hybrid number 4 . 5 r !Wt. of hybrid, [ i n grams) f i P l a n t s F. Av, Wt. of progeny (samples i n grams) Fg -- - Maximum Wt. f o r progeny j sample I F f 2 172 ! . 92..4. 208 56 148 ' . -57.2 j 167 ; 68 123 55 » 7 j 9 1 1 71 136 24.9 41 100 - ; ; 32.7 1 • 76 190 263 48.9 1 79. Average 157 52 © 1 j 120.3 . .,' L _ _ _|: J Table 12B Ht. Comp ar i s ons . Hybrid number Ht. of h y b r i d ^in inches) .Plants Av. Ht. f o r ! , tprogeny sample, ( i n i n c h e s ) ! Maximum Ht J f o r progenj- sample ( i n : inches) 28 25 «> 4. .. i 32 ' 56. '' j 24 20.3 ' 29 " 68 . 20 19.7 27 • 23.: 13.5 . 156 24 14.8 2.L- 1 190 ! 30 1 14,9 22 Average 24.8 j i s . i 25.1 29 2. Y i e l d and Pleight A great amount of data was a v a i l a b l e f o r t h i s c o r r e l a t i o n . The m a t e r i a l used was the f o u r t h generation plants from the o r i g i n a l 7 hybrids. Plants were s e l e c t e d at random from t h i s large group and c o r r e l a t i o n s run on them. Unfortunately there was only a v a i l a b l e the data f o r 1928 making impossible to make a year to study. The r e s u l t s are g i v e n i n Table I Table I C o r r e l a t i o n No. of Plants F i e l d C o r r e l a t i o n Numbers Designation C o e f f i c i e n t s The c o r r e l a t i o n s are a l l p o s i t i v e and range from -/- 0.35 to -f- 0.88. By f a r the l a r g e r number have a high c o r r e l a t i o n which would seem to i n d i c a t e that there i s 3. high c o r r e l a t i o n between height of p l a n t and y i e l d of p l a n t . The same r e s u l t s were obtained by Hacbarth and Ufer (29), Burton (5) and K i r k (17). This c o r r e l a t i o n , however, i s not absolute as seen i n the 30 two values which give -h 0,35 and -f- 0.45, 3» A s s o c i a t i o n Leaf Spotting Incidence and % Ovules Developing on Racemes* Leaf s p o t t i n g i s very prevalent and i s due to a disease ffeeudopeziea medicaginis. I t was thought that there might be an impairment of p h y s i o l o g i c a l a c t i v i t y due to l e a f s p o t t i n g . I f there i s any i t does not manifest i t s e l f i n the number of ovules developing on the racemes. Table 2 shows the l e a f s p o t t i n g incidence p l o t t e d against the % ovule development. Table 2 Leaf Spot •'•Incidence 0 -50% 50% -80% 80% - 100% % • 1 • 3 (4.2) ' '21V' - (19.6) 11 (11.2) 35 2 6 (4.8) 21 (22.4). 13 (12.8) 40 Dotal 9 .,. 42 24 '"75 ' '. Mo, 1 denotes high incidence and 2. low. The top v a l u e . i s the a c t u a l number while the lower i s the t h e o r e t i c a l . The c h i square f o r 2 degrees of freedom at the 5% l e v e l of s i g n i f icanc e i s 5.99 9 wMehh Indicates that there i s no a s s o c i a t i o n between the degree of l e a f spot present and the number of ovules developing. 31 4» A s s o c i a t i o n of Leaf Spotting and Leaf Color. L i t t l e i s mentioned i n the l i t e r a t u r e regarding the e f f e c t that l e a f spot may have on a l f a l f a . Present i n d i c a t i o n s are that i t i s i n c r e a s i n g . Table 3 gives the d i s t r i b u t i o n f o r the incidence of l e a f spot and l e a f c o l o r . Table 3 • Leaf .Spot Incidence 5 1 • 1 . 2 Foliage Color Dark 23 (24.1) 26 (15.4) 49 L i g h t 15 (13.8) 13 (14.1) 28 - 38 / 39 77 m Leaf Spotting? 1 high incidence 2 med» .& low incidence The m a t e r i a l s used here were 77 plants s e l e c t e d at random f r o m t h e F^ progeny. The c h i square f o r 1 degree of freedom at the 5% l e v e l of p r o b a b i l i t y was 3.84 . This i n d i c a t e s there i s no s p e c i a l s i g - n i f i c a n c e between f o l i a g e c o l o r and the amount of l e a f s p o t t i n g . It should be noted i n t h i s connection that a boron d e f i c i e n c y w i l l a f t e n give a p a l e r l e a f . However, i n t h i s ease the d i f f e r e n t colors of leaves could hardly be a t t r i b u t e d to n u t r i t i o n a l f a c t o r s . 32 5, As s o c i a t i o n l e a f spot and Flower Abundance. Instead of a f f e c t i n g the seed y i e l d d i r e c t l y the l e a f spot might have reduced the number of flowers,thereby decreasing the seed y i e l d . -A comparison of flower abundance and l e a f s p o t t i n g i s given i n Table 4. Random s e l e c t i o n s from the F^ progeny were used f o r these s t u d i e s . Table 4 Poor F a i r Good 1 13 (918) 13 (14.3) 13 (13.8) 38 2 7 (10.1) 16 (14.7) 16 (14.2) 39 T o t a l 20 29 28 77 The l e a f spot incidence was d i v i d e d i n t o 2 categories Xdenoting high degree of l e a f s p o t t i n g and 2 low. The flower abundance was d i v i d e d i n t o 3 c l a s s e s , poor, f a i r , and good. The c h i square at 2 degrees of freedom at the 5% of prob- a b i l i t y was 5.99, which would i n d i c a t e t h a t l e a f s p o t t i n g has not s e r i o u s l y influenced the number of fl o w e r s . The number^ of samples used was s m a l l and a d i f f e r e n t a s s o c i a t i o n might be obtained using l a r g e r numbers. 33 6. A s s o c i a t i o n of Stem Thickness and Plant Height. The materials used f o r t h i s a s s o c i a t i o n were s e l e c t i o n s from Rogers (24) a l f a l f a . 75 plants were se l e c t e d at random and a e h i square run on these. The stem thickness was given 3 designations, t h i n , medium, and t h i c k f the height was also d i v i d e d i n t o 3 categories, 25 inches and l e s s , 25-30 inches, and 30 inches and more. Table 5 gives the d i s t r i b u t i o n . Table 5 Plant He ight(Inches) 0 - 2 5 25- 30 30 & over T o t a l Stem. Thin 18 (8.9) 3 (7.5) 0 (4.48) 21 t h i c k n Medium 13 (14.9) 18 (12.6) 4 (7.4) 35 Thick 1 (8.1) 6 - (6.8) 12 (4) 19 T o t a l 32 27 16 75 The c h i square at the 5% l e v e l of p r o b a b i l i t y and 4 degrees of freedom was 9.49 which would i n d i c a t e avery strong a s s o c i a t i o n between thickness of stem and p l a n t height. However, i t might be p o s s i b l e to s e l e c t a t a l l growing pl a n t w i t h a t h i n g stems Burton (5) found a strong a s s o c i a t i o n between'height and number of stemso 3 4 7 . A s s o c i a t i o n of Height and Spread, Materials used were random s e l e c t i o n s from the progengy i n v o l v i n g 5 0 0 plants. Awere taken by the Department of Agronomy i n the e a r l y summer. K i r k ( 1 7 ) and Armstrong and White ( 1 ) found a p o s i t i v e c o r r e l a t i o n between these 2 characters. Table 6 gives the d i s t r i b u t i o n . Table 6 2 t * 1 5 • • » • • • • • • . • • • • » a •» ft 1 3 3** 1 3 * • » • • • • • « « • • . . . f . 0 3 4.** 3 • . . " ^ , 3 0 5 ™ ^ 1 . . . . / » » 1 6 7 • » . . . 1 5 7 * * ^ • * . • ^ . 3 5 • . . . . 2 4 1 0 * ^ 1 9 • - , 0 7 1 1 * * 1 5 • • . ^ , 2 3 1 2 * " * 1 1 * e » * 9 « * * 9 0 V . . . f . 2 6 1 3 ™*2yL, • • • • • 2 3 1 4 ~ * 2 3 * • • • » • • • « » - • » • • • * ^ » 2 4 The c o r r e l a t i o n i s p o s i t i v e but low though i n some l i n e s the a s s o c i a t i o n i s q u i t e strong. I t should therefore be pos s i b l e to s e l e c t "tatfe growing plants which are spreading. 35 The stage of growth at which these c o r r e l a t i o n s are taken i s important. The above mentioned pla n t s were r e l a t i v e l y mature, e a r l i e r c o r r e l a t i o n s may have been b e t t e r , 8. A s s o c i a t i o n of Flower Abundance and Raceme Supporting Ovules. I t was thought that the flower abundance would have a considerable e f f e c t on seed.development. The f o l l o w i n g studies deal w i t h the e f f e c t of flower abundance on various c h a r a c t e r i s t i c s a f f e c t i n g seed y i e l d . Table 7. FLower Abundance Racemes % Remaining, 0-50 50-80 80-100 i i i * Total' Poor ' (2.63) 13 1 (11- 37) ! (6.1) J 20 F a i r 3 (3.4) -15 (16.9) 12 (9.1) 30 Qbod 7 (3.4) | . 15 I (14.2) 1 i 4 1(7.8) ! 26 .Total. 10 ] •' 43 ' 23 i 76 The flower abundance was d i v i d e d i n t o 3 categories, poor f a i r , andgood and the percentage of flowers remaining were 36 divided into 3 classes according to percentage 0-50%, 50-80%, 80-100%. There i s no a s s o c i a t i o n "between the flower abundance, and the number of racemes remaining. The c h i square at the5% l e v e l of s i g n i f i c a n c e i s 9.49 which indic a t e s ho r e l a t i o n s h i p . 9. A s s o c i a t i o n of Foliage Color and Flower Abundance. Rogers a l f a l f a (24) was used f o r t h i s c o r r e l a t i o n . The f o l i a g e c o l o r was d i v i d e d into l i g h t and dark and the flower abundance into 3 classes poor, f a i r and good. Table 8 Foliage Color Flo Poor wer Abunc | F a i r lance Good Tota l Dark Green 10 ' (12.0) 18 (17.7) 19 ( 17.1) 47 Light Green 9 (6.9) 10 (10.2) 8 (9.8) 27 T o t a l 19 28 27 : 74 .: As would be expected there was no r e l a t i o n s h i p i n t h i s a s s o c i a t i o n . The c h i square f o r 2 degrees of freedom at the 5% l e v e l of p r o b a b i l i t y i s 5;»99"e Here again the p o s s i b i l i t y of the e f f e c t of a boron d e f i c i e n c y must not be overlooked. 37 10. As s o c i a t i o n of Flower Abundance and Flower F a l l . \ In some cases there were a large number of flowers that f e l l e a r l y i n development I.e. long before pods had begun to form. In Table 9 the flower abundance i s d i v i d e d i n t o 3 classes poor, f a i r and good, and the amount of flower f a l l i n t o 3 classes 0-50,50-80 and 80 and over. Table 9 Slower ibundance Amount of 0- 50 Flower 1 50-80 ? a l l -80- . T o t a l Poor (2.63) 13 (11.3) 7 (6.1) 20 Fair 3 (31.9) 15 (16.9) 12 (9.1) 36 3ood 7 (3.4) 15 (14.7) ' 43 4 £7.8) 26 Total 10 ,23 76 M a t e r i a l s used were random s e l e c t i o n s from the -F4 progeny.' The c h i square at the 5% of p r o b a b i l i t y and 4 degrees of freedom i s 5.81 which would i n d i c a t e no a s s o c i a t i o n . 38 FLOWER COLOR, OTHERITANCE S!32UDIES. Flower Color Inheritance Studies i n A l f a l f a . The flower colors have been placed i n 15 c a t e g o r i e s A l - though the v a r i e g a t l s j % colors are predominately blue or purple there appeared variegated flowers which wens b a s i c a l l y yellow or green or a mixture of t h i s w i t h blue and purple»: The m a t e r i a l used was the F Q of the o r i g i n a l 7 hybrids. Table 1 gives t h e i r d i s t r i b u t i o n . T h e ' f i r s t column indi c a t e s the h y b r i d from which the plants were derived. Table 1 H # 7 # 56 # 68 # 71 # 156 # 190 0 ) H ft PM 2 3 3 1 1 0 ) m > H ft 3 PM > CD H ,Q I Q) H ft 3 6 2 1 ' CD H ft Sh P4 I CD H cd PM 1 2 CD CO d) »r! O HI ft 1h 13 13 20 2 6 8 o a) •H 3 4 0) •a 1 1 1 1 CD H I P» o H H > CD H ft ft H o H H iS I ci CD cis 3 2 8 18 o i—l H 12 1 5 13 12 3 -d CD -P cS hQ CD •rt 4-3 0) H ft & P-t The designation of a c t u a l colors presented a great d i f f i c u l t y . Some plants weas-different c o l o r s during the various stages of 39 t h e i r blooming p e r i o d . > A large number of r a t i o s were t r i e d but none f i t t e d , , Color inheritance Is probably f u r t h e r complicated due to the p o l y p l o i d nature of the m a t e r i a l . . In table 2 the color classeswere cut down to 3. The flowers wer b a s i c a l l y purple, green or yellow and were c l a s s - i f i e d on that b a s i s . Table 2 Parent Plant — — — , Pnrple & Blue f — — 1 1 Green i '• Yellow. #7 21 • 0 12 #56 30 ' I #68 17 8 • #71 7 . • i s . ; . ! ^ #156 10 12 #190 8 ; 20 •. .3 , Lepper and Qdlqnd^ (20) put flower color Inheritance i n a l f a l f a on a 3 f a c t o r b a s i s . Their hypothesis was not d i s - proved. However, "pure yellow" occurs much l e s s f r e q u e n t l y than expected. Out of 185 Fg p l a n t s , whites and yellows are not recovered a t a l l . They are recovered f a i r l y f r e q u e n t l y i n l a t e r generations. P o l l i n a t i o n c o n t r o l may not have been s a t i s f a c t o r y . E i t h e r some cr o s s i n g may have taken place or the 40 numbers of progeny received were not s u f f i c i e n t f o r accurate conclusions. The hybrids are p o l y p l o i d and therefore not l i k e l y to y i e l d many yellows and whites t i l l l a t e r generations. The general segration d i s t r i b u t i o n , however, suggests an inheritance pattern i n v o l v i n g s e v e r a l p r i n c i p a l mendelian factors', with f a c t o r s f o r purples and blues e p i s t a t i c to those f o r yellow and white. 41 DISCUSSION The r e s u l t s obtained from t h i s work are of i n t e r e s t i n r e l a t i o n to the p r a c t i c a l bearing, which they may have on the problem of a l f a l f a improvement. When s e l e c t i o n i s desired for. a ce r t a i n , character j i t i s often d e s i r a b l e to determine, i f p o s s i b l e , which other characters of the. p l a n t , i f any, are associated w i t h i t . By s e l e c t i n g f o r o n e r ; f t may be, poss i b l e to secure the other a l s o . However, i n crop improvement work a breeding program must go hand i n hand wi t h c o r r e l a t i o n s t u d i e s . I t i s p o s s i b l e to generalize On the p o s s i b i l i t i e s of inbreeding and hybridyktlon as a means of improving a l f a l f a . As i n most normally cross f e r t i l i z e d crops there i s a reduction of v i g o r upon Inbreeding. However, some l i n e s showed no l e s s - ening of v i g o r upon s e l f - f e r t i l i z a t i o n , which seems to i n d i c a t e that the d i f f e r e n t i a l e f f e c t of s e l f - f e r t i l i z a t i o n i s due to the genetic c o n s t i t u t i o n . In t h i s i n v e s t i g a t i o n emphasis has been placed upon seed production. At present the major problem i s to develop a vigorous p l a n t which i s also a good seed y-ielder. An abundance of flowers would appear to have some bearing on the f i n a l seed production. Many f a c t o r s both genetic and environmental a f f e c t these c h a r a c t e r i s t i c s of the p l a n t . High and low f e r t i l i t y and v i g o r are apparently inherited,, However, environmental conditions must be s a t i s f a c t o r y before a plant w i l l f u n c t i o n to i t s optimum. I t i s hoped that the c o r r e l a t i o n e s t a b l i s h e d , both p o s i t i v e and negative, between seed y i e l d 42 and other c h a r a c t e r i s t i c s w i l l prove of help i n future a l f a l f a improvement work. Pigmentation does not appear to have any e f f e c t on any of the characters studied. Both flower c o l o r and the degree of pigmentation of the leaves y i e l d e d no d e f i n i t e a s s o c i a t i o n s . Leaf spot was the only disease of which there was any evidence*Other than its•appearance on the leaves i t d i d not appear to have any e f f e c t e i t h e r morphologically or physio- l o g i c a l l y . In some of these studies s u f f i c i e n t numbers were a v a i l - able but i n others due to the l a c k of time and f a c i l i t i e s , the number of samples taken were few. I t should therefore be cautioned that i n these "cases where l i m i t e d numbers were used conclusive r e s u l t s are impossible. Further work may y i e l d d i f f e r e n t conclusions. CONCLUSIONS • S e l e c t i o n w i t h i n s e l f f e r t i l i z e d l i n e s appears to provide a primary' mode of attack f o r the breeding of improved v a r i e t i e s of a l f a l f a . As i n d i c a t e d ' i n these and other studies there i s a general reduction of v i g o r lipon s e l f p o l l i n a t i o n . However, a few plants r e t a i n t h e i r good c h a r a c t e r i s t i c s even upon s e l f - i n g . When superior inbred strains.have been obtained which are vigorous enough to replace the heterogenous v a r i e t y now grown, the breeding program beSmes r e l a t i v e l y simple,, These studies show that there i s a general reduction of seed y i e l d , p l a n t y i e l d and plant height between the F^ and F2. But a few plants tend to r e t a i n the good q u a l i t i e s of the parent. Seed y i e l d was s t u d i e d i n some d e t a i l and i t was shown that high y i e l d i n g plants had a greater number of t w i s t s per pod. Open p o l l i n a t i o n and good weather had a b e n e f i c i a l e f f e c t on the amount of seed s e t . The abundance of flowers seemed to be an i n d i c a t i o n of f i n a l seed y i e l d i . e . an abundance of flowers would give a good seed-set. However, due to the small number of samples involved and some d i f f i c u l t i e s encountered i n the f i e l d , t h i s r e s u l t can by no means be taken as absolute. Leaf spot and flower c o l o r , on the other hand, gave no assoc- i a t i o n w i t h seed y i e l d at a l l . S e l f f e r t i l i z a t i o n tended to decrease the seed y i e l d . Whether handling of the racemes i n the processes e f f e c t i n g f e r t i l i z a t i o n increased or decreased the f i n a l seed y i e l d , i s uncertain. These r e s u l t s i n d i c a t e that flov/er abundance i s no i n d i c a t i o n of alisuperiorcplan'ti'il.Associations of t h i s character w i t h 44 f o l i a g e color. ? l e a f spot and percentage of ovules developing on the raceme gave no p o s i t i v e results» The stem, on the other hand,' i s a f a i r l y r e l i a b l e i n d i c - a t i o n of a superior p l a n t . Correlations between the height of the stem and stem width, plant y i e l d and spread a l l gave p o s i t i v e r e s u l t s . Leaf spot d i d not appear to hinder the a c t i v i t y of the plant at a l l . There was no a s s o c i a t i o n between l e a f spot and flower abundance, l e a f color or percentage of ovules developing.on the raceme. Several uns-uccessful attempts were made to reach some conclusion regarding the mode of flower c o l o r i n h e r i t a n c e . Various workers have suggested hypothesis f o r flower c o l o r inheritance of a l f a l f a but the author was unable to f i t any of these to her r e s u l t s . I t i s hoped that t h i s work w i l l contribute something to future a l f a l f a improvement work. I t was unfortunate that i n some cases data was very l i m i t e d . These r e s u l t s can only be used as i n d i c a t i o n s . However, f u r t h e r i n v e s t i g a t i o n using l a r g e r numbers may contribute some d e f i n i t e conclusion. SUMMARY 4 5 I There was a s i g n i f i c a n t a s s o c i a t i o n between pod shape and number of seeds per pod f o r s e l f p o l l i n a t i o n m a t e r i a l , 2. There was a h i g h l y s i g n i f i c a n t c o r r e l a t i o n between number of seeds per pod and pod shape i n the open p o l l i n a t e d m a t e r i a l , 3 Low seed y i e l d i n g plants tend t o have s t r a i g h t podsf high seed y i e l d i n g plants tend to have twisted pods, 4 There i s probably some a s s o c i a t i o n between many flowers w i t h a large seed s e t but data are too scanty to put much r e l i a n c e on i t , 5 There i s a. s i g n i f i c a n t d i f f e r e n c e i n seeds (a) per pod between s e l f and open p o l l i n a t e d racfmes, (b) there i s a s i g n i f i c a n t c o r r e l a t i o n between pods w i t h abundant seed inboth open p o l l i n a t e d and s e l f p o l l i n - ated, 6 There i s no a s s o c i a t i o n between flower c o l o r and seed y i e l d , 7 Comparisons between seed y i e l d of successive years showed a d e c l i n e . However, a good seed y i e l d e r tended to remain good seed y i e l d e r s , 8 There are d i s t i n c t l y more high y i e l d i n g plants than ex- pected i n a normal d i s t r i b u t i o n curve, 9 Comparisons of seed y i e l d , plant y i e l d and plant height between the F-j_ and Fr, showed a reduction i n general, 1 0 There i s no a s s o c i a t i o n of flower abundance and floxver c o l o r . 4 6 11 There i s no a s s o c i a t i o n between, l e a f s p o t t i n g incidence and flower abundance, 12 There i s no a s s o c i a t i o n between flower abundance and the percentage of ovules developing on the racemes, 13 There i s no a s s o c i a t i o n between flower abundance and flower f a l l , 14 There i s no a s s o c i a t i o n between flower abundance and l e a f dolor* 15 There i s a strong c o r r e l a t i o n between stem thickness and stem height, 16 There i s a p o s i t i v e c o r r e l a t i o n between plant height and plant y i e l d . The p o s i t i v e c o r r e l a t i o n i s high but not absolute, 17 There i s a c o r r e l a t i o n between pla n t height and spread. 18 There Is no a s s o c i a t i o n between l e a f s p o t t i n g incidence and l e a f c o l o r , 19 There i s no a s s o c i a t i o n between l e a f s p o t t i n g incidence and the percentage of ovules developing on the racemes, 20 Ho conclusions were a r r i v e d at regarding the mode of flower color i n h e r i t a n c e . 46 1, Armstrong, J.M.' and White, W. J . Factors A f f e c t i n g Seed S e t t i n g i n A l f a l f a : Jour of A g r i c . Science, V o l , 25 - 1935, 2, Bolton, J.L. and F r y e r , J.M. In t e r p l a n t V a r i a t i o n s i n Certain Seed S e t t i n g Processes i n A l f a l f a s Sex. A g r i c , V o l , 18 - 1937, 3, Brink, R.A, and Cooper, D.D. Somatoplastic S t e r i l i t y i n M, s a t i v a : S c i , News Serv i c e , V o l , 90, 4, Brink, R..A. and Cooper, D.C. P a r t i a l and S e l f Incompatability and the Collapse of F e r t i l e Ovules as Factors A f f e c t i n g Seed Formation i n A l f a l f a : Jour, A g r i c , Research, Vol,.60 - 1940 5, Burton, G.W. ' A l f a l f a Inheritance Studies i n New Jersey: Am, Soc. Agroa. Jour,, V o l , 27 - 1935 6, Carlson, J,W. A r t i f i c i a l T r i pping of Flowers i n A l f a l f a i n R e l a t i o n to Seed Production? Jour, of Am. Soc, Agroa,, V o l , 22 1930. 7, Clarke, A.E. and Fryer, J.M, s Seed S e t t i n g i n A l f a l f a : S c i . A g r i c . , V o l . 11 - 1930 8, Cooper, D.C. ' Embryo M o r t a l i t y i n R e l a t i o n to Seed Formation i n A l f a l f a s Am, Jour, of Bot., V o l . 24, 1937. 9^ Dwyer, R.E.P, Lucerne Breeding Technique - A New System of Close Breeding: Herbage Reviews, V o l . 4- 1936 10, Englebert, V. A Study of Various Factors Influencing Seed Production i n A l f a l f a s S c i . A g r i c . , V o l . 12 - 1931. 11, F a r l e y , H. A C y t o l o g i c a l Study of U. B. C. A l f a l f a s M.S.A. Thesis 1936 - unpublished. 12, Freeman, G.F. P h y s i o l o g i c a l C orrelations and C l i m a t i c Reactions i n A l f a l f a Breedings Am. Nat., V o l . 48 - 1941, 13, G r i z z a r d , A.L. and Matthews, E. M. E f f e c t s of Boron on Seed Production of A l f a l f a s Jour. Am. Soc. Agron., V o l . 34 -1942 14.. Hay, W.D. D o e s . . A r t i f i c i a l Tripping of- A l f a l f a Blossoms Increase Seed S e t t i n g ! S c i . A g r i c , V o l . 5, 1924, .15. Hut chins on ? A. H, and Farley., H. • ' Seed Development i n Medicago Hybrids| Normal Ovule Canadian Jour. Research, V o l , 19, 1941, 16. Jones, F.R. Evidence of Resistance i n A l f a l f a , Red Clover and Sweet Clover to Certain Fungus Parasites? Phyt., V o l . 31- 1941. 17* K i r k , L.E. S e l f F e r t i l i t y i n R e l a t i o n to Forage Crop Improvement! Sc. A g r i c , V o l , 8 - 1927 18, Ledingham, G. F. G y t o l o g i c a l and Developmental Structures of Hybrids Between M. s a t i v a and a D i p l o i d M. Falacata: Genetics, V o l . 25- 1040. 19. Lejeune, C.J. and Olson, P.J. Seed S e t t i n g i n A l f a l f a 5 Sc. A g r i c , V o l . 20 - 1939. 20. Lepper, R. and Odland, T.E. Leaf Mutation i n A l f a l f a : Journ. Am. Soc. Agron. 9 V o l . 31 - 1937. 21, Lepper, R and Odland, T.E. Inheritance of Flower Color i n a l f a l f a : Journ. Am. .Soc Agron., V o l . 31- 1937. '22. McVicar, R. F. ' Inheritance of Seed Colour i n A l f a l f a : S c A g r i c V o l , 15 - 1934. 23. Moe, G.G. • Inherantance Studies of A l f a l f a s 1928 Thesis - Unpublished. 24. Rogers, C.B. W. Rhizome Studies of A l f a l f a s M.S.. A. Thesis - 1941 Unpublished. 25. Southworth, W» Influences Which Tend to A f f e c t Seed Production i n A l f a l f a and an Attempt to Raise High Seed Producing S t r a i n s by Hybridizations S c A g r i c . , V o l . 9 - 1928. 26. Stewart, G. A b n o r m a l i t i e s i n Inbred A l f a l f a and Surgar Beets 1 Jour, of Hereditary, V o l . 25, 1934. 27. Stewart, G« The E f f e c t s of Inbreeding on V a r i a b i l i t y i n A l f a l f a s Jour. A g r i c . Reasearch, V o l . 49- 1934 s 28. Tysdal, H. M. Is Tripping Necessary f o r Seed S e t t i n g i n A l f a l f a s Jour. Am. Soc. Agron., V o l . 32s 1940. 29. Tysdal, HvR. and Clark, I . ' = Improvement of A l f a l f a Seed Production by Inbreedings Jour. Am. Soc. Agron., V o l . 26-1934. 30. Tysdal, H.R. And Westover. A l f a l f a Improvements U. S. A g r i c . Year Book - 1937.

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