Theoretical and Applied Genetics 39, 88--94 (1969)

Serial Analysis of Combining Ability in Diallel and Fractional Diallel Crosses in Linseed I. J. ANAND and B. R. MURTY D i v i s i o n of Genetics, I n d i a n A g r i c u l t u r a l R e s e a r c h I n s t i t u t e , N e w Delhi Summary. An analysis of the nature of the gene action for seven characters influencing p r o d u c t i v i t y and wide adaptation in L i n u m usitatissimum L. was undertaken in this investigation over three seasons based on diallel and fractional diallel crosses, among a set of ten genetically diverse parents. Estimation of combining ability and the nature of genotype-environment interactions for the above characters was also examined. A comparison of the means of the parents and hybrids over three environments showed positive heterosis for height, number of tillers, fruit-bearing branches and capsules per p l a n t while negative heterosis was observed for flowering time. The remaining two characters viz., height at branching and seeds per five capsules showed little differences due to mutual cancellation of the components of heterosis. A serial analysis of combining ability over three seasons using GRIFFING'S model (1956) has revealed significant seasonal effects on the estimates of combining ability effects. Additive gene action was found to be predominant in most of the characters although non-additive variation due to s.c.a, was equally prominent for fruit-bearing branches and capsules per plant. On the basis of g.c.a, for all the characters, M. t0 and N. 55, both Peninsular types were the best followed b y N.P. (R.R.) 45 and Mohaba Local. I n the fractional diallel analysis the relative estimates g.c.a, and s.c.a, were similar for s = 9 and 7. However, there was overestimation in favour of s.c.a, when s was reduced to 3. The serial analysis of fractional diallel had confirmed the results of full diallel. Significant genotype • environment interactions for flowering time, height, height at branching, fruit-bearing branches and capsules per p l a n t were observed in this analysis also. The results have indicated t h a t reduction of the diallel to a fraction with s = n/2 would vitiate the order and precision of estimates of combining ability. The analysis of genotype • environment indicated t h a t the p a t t e r n of interactions among the parents of different geographical groups was not similar but varied with the character under study. Considerable interactions were observed for capsules per plant, fruit-bearing branches and flowering time in t h a t order respectively. A comparison of the parental and hybrid populations for the degree of interaction for all the characters had revealed t h a t heterozygosis might not at all be directly related to the degree of homeostasis. Actually, heterozygotes were found to show more interactions t h a n homozygotes for flowering time, height at branching and tiller number and lower interactions for the other four characters. Significant seasonal effect on the degree of heterosis for vegetative as well as reproductive characters was observed in a m a j o r i t y of F l ' s with variable degree of dominance.

T h e a d v a n c e u n d e r selection for y i e l d in linseed in I n d i a h a s n o t r e a c h e d t h e e x p e c t a t i o n s on t h e basis of p r e d i c t i o n s from t h e p e r f o r m a n c e of e a r l y g e n e r a tions. S t r o n g n e g a t i v e a s s o c i a t i o n b e t w e e n some of t h e y i e l d c o m p o n e n t s , g e n e t i c s l i p p a g e d u e to unp r e d i c t a b l e successive e n v i r o n m e n t s , a n d t h e loss of genes for p r o d u c t i v i t y w i t h i n t e n s i v e selection for disease r e s i s t a n c e u n d e r p o o r soil f e r t i l i t y could be some of t h e causes (JESWANI a n d MURTY, t963). H o w e v e r a d e q u a t e i n f o r m a t i o n on t h e role of genot y p e - e n v i r o n m e n t i n t e r a c t i o n s is n o t a v a i l a b l e in this crop. I t has also b e e n r e p o r t e d t h a t g e n e r a l c o m b i n ing a b i l i t y is l e a s t influenced b y such i n t e r a c t i o n s in m a i z e a n d t o b a c c o (RoJAS a n d SPRAGUE, 1952; MATZlNGER, MANN a n d COCKERHAM, 1962). A serial a n a l y s i s of c o m b i n i n g a b i l i t y of m a i n effects a n d int e r a c t i o n c o m p o n e n t s of g e n e t i c v a r i a t i o n in a n u m b e r of diallel crosses b e t w e e n p a r e n t s chosen on t h e basis of g e n e t i c d i v e r s i t y m i g h t give an i d e a of t h e n a t u r e a n d m a g n i t u d e of such i n t e r a c t i o n s . This will also h e l p to e x a m i n e t h e changes in t h e e s t i m a t e s of c o m b i n i n g a b i l i t y o v e r seasons. T h e results of such a s t u d y in diallel a n d f r a c t i o n a l diallel sets are r e p o r t e d in this p a p e r .

Materials and Methods T h e e x p e r i m e n t a l m a t e r i a l u s e d in t h e p r e s e n t i n v e s t i g a t i o n c o m p r i s e d of a set of t e n v a r i e t i e s , chosen on t h e basis of t h e i r g e n e t i c d i v e r s i t y as m e a s u r e d b y D2-statistic. A m o n g s t these, t h r e e were exotics, t h r e e P e n i n s u l a r s f r o m D e c c a n P e n i n sula, t h r e e I n d o - G a n g e t i c s from I n d o - G a n g e t i c plains, a n d t h e t e n t h a d e r i v e d line a d a p t e d to b o t h I n d o G a n g e t i c a n d P e n i n s u l a r regions as r e p o r t e d in an earlier p a p e r (MuRTYa n d ANAND, 1966). T h e t h r e e e x o t i c s were u s e d as d o n o r s for r u s t r e s i s t a n c e a t t h e D i v i s i o n of Genetics, I n d i a n A g r i c u l t u r a l R e s e a r c h I n s t i t u t e , New Delhi, in I n d i a . T h e p a r e n t a l v a r i e t i e s w h i c h were selfed for s e v e r a l g e n e r a t i o n s p r e v i o u s l y , were crossed in all possible c o m b i n a t i o n s in t h e y e a r s 1963, t964 a n d t965 so as to m a k e a c o m p l e t e diallel set w i t h o u t reciprocals. T h e 45 F1 h y b r i d s t h u s o b t a i n e d in each y e a r were sown along w i t h p a r e n t s in a r a n d o m i s e d c o m p l e t e b l o c k design w i t h t h r e e r e p l i c a t i o n s in t h e following w i n t e r season. T h e s p a c i n g was t 2 inches b e t w e e n rows a n d four inches w i t h i n rows of t e n feet length. F i v e p l a n t s were s e l e c t e d a t r a n d o m in each row a n d o b s e r v a t i o n on seven c h a r a c t e r s r e l a t e d to p r o -

Vol. 39, No. 2

Combining Ability in Diallel and Fractional Diallel Crosses in Linseed

ductivity i.e. flowering time (recorded as the number of days from the date of sowing to the opening of first flower), height (measured in centimeters from the base to the tip of the main tiller at maturity), height at branching (measured in centimeters at the time of maturity), tiller number, fruit-bearing branches, capsules per plant and seeds per five capsules were taken. The estimates of general and specific combining ability effects and analysis of variance for combining ability was done on the fixed effects model described by GRIFFING (~9~6). Fractional diallel sets corresponding to s = 9, 7, 5 and 3 were formed from the full diallel sets and the data on the above characters were analysed for the first two seasons. The sampling and analysis of fractional diallels followed the procedure outlined by KEMPTHORNE and CURNOW 0961). Pooled analysis of full and fractional diallels over three different seasons was carried out. Results A comparison of the means of the parents and hybrids over the three environments revealed that the hybrids showed positive heterosis for height, number of tillers, fruit bearing branches and capsules per plant while negative heterosis was observed for flowering time. The remaining two characters viz., height at branching and seeds per five capsules showed little hybrid vigour due to mutual cancellation of the components of heterosis. A combined analysis was done for the full diallel without reciprocals based on individual plant observations for the three seasons, to examine the nature of genotype • environment interactions (Table t). The variation amongst the hybrids was larger than that among the parents except for the character seeds per five capsules. The differences between parents and hybrids pooled over environments were substantially high for almost all the characters except seeds per five capsules, indicating marked heterosis. Significant seasonal effects with interactions due to genotypes • years were indicated for all the characters. The interaction of hybrids • years was more than that of parents • years for flowering time, height at branching and number of tillers, while it was the opposite for the remaining characters. Therefore, heterozygosity did not appear to be related to the magnitude of these interactions. The interaction of (Parents vs. hybrids) • years was significant for six characters indicating that heterotic effects varied with seasons9 Actually, heterosis was found to be maximum in the most favourable season in t964 to 1965. The pooled analysis of combining ability of the three seasons is given in Table 2. The variations due to general and specific combining ability and their interactions with years were significant. The seasonal effects on both general and specific combining ability

89

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Theoret. Appl. Genetics

I. J. ANANDand B. R. MvR'rx':

Table 2. Pooled diallel analysis for combining ability over three seasons in linseed Source

D.F. Flowering time

G.C.A. S.C.A. Years G.C.A. • Years S.C.A. • Years Error

9 395.10"* 688,t 7** 45 14.8t** 17.30"* 2 24021.50** 14643.50** 18 523.06** 779.80** 90 52.~6"* 39.87** 1980 t.66 1.50

Height

Height at branching

Fruit Number of bearing tillers branches

342.03** t4.15"* 7845.50** 385.83** 35.26** 4.t0

12.89"* 2.o1"* 2084.25** 21.81"* 7.01 ** 0.50

Capsules per plant

Seeds per capsule

744.00** 8579.72** 10.33"* 342.83** 3395.42** 1.58'* 1733493.00** 20351915.00** 768.00** 1624.57"* 18450.66** 19.64"* 945.59** 8519.9I ** 5.96** 55.55 439.22 0.50

** Significant at t % level. -- G.C.A. = General combining ability. -- S.C.A. = Specific combining ability Table 3. Pooled estimates of general combining ability effects of ten parents of linseed over three seasons General combining ability effects Parents

F10weringHeight time

Height at Number of branching tillers

1. 2. 3. 4. 5. 6. 7. 8. 9. 1o.

5.08 --4.{)5 --6.37 --2.52 7.18 --3.29 11.05 --1.87 --0.96 --4.32

--4.83 -- 5.76 --7.05 --3.16 5.38 t7.56 5.74 --1.8{) --4.93 --1.13

-2.06 -- 5.o9 --5.76 -2.47 1.57 tl.32 6.98 --I.11 --2.1o --1.27

0.35 0.52

0.33 0.49

0.55 0.82

N.P. 12 (G) N. 55 (i') M. I0 (P) Mayurbhang (G) Afghanistan-2 (E) Wada (E) A. t 7-I-1 (g) N.P. (R.1C) 9 (G,P) N.P. (R.R.).45 (G) Mohaba local (P)

S.E. ~i S.E. (~i-- ~j)

Fruit bearing branches

o.46 -- 1.27 N.S. --o.2t N.S, 6.24 1.40 8.21 --0.32 N.S. --1.51N.S. 0.87 8.35 --2.50 --17.79 --0.o8 N.S. 3.0I N.S. --OA9 N.S. --6.09 0.49 3.10 o.o7N.S --2.24N.S o.19 0.28

2.04 3.04

Capsules per plant

Seeds per five capsules

--8.28 N.S. 13.81 23.1I --3.76 N.S. 38.59 --59.84 5.99 N.S. --14.49 ~4.59 --9.72N.S.

o.31 N. S. --1.14 --0.94 0.48 1.3o 1.44 o.12 N.S. o.o6 N.S. --o.92 --0.72

5.73 8.55

o.19 0.28

N.S. = Not significant. -- G: Indo-Gangetic; P: Peninsular; E: Exotic; G.P: Suitable for both Gangetic and Peninsular regions. were considerable. Predominantly additive gene action was indicated for flowering time, height, height at branching, fruit-bearing branches and capsules per plant. Variation due to specific combining ability was also large for fruit-bearing branches and capsules per plant. The pooled estimates of general combining ability effects (g.c.a.) for the ten parents are given in Table 3. M. t0 was the best combiner for all the characters except seeds per five capsules, followed by N. 55, N.P. (R.R.) 45 and Mohaba Local. Afghanistan-2, which resembles a flax type had a high combining ability for fruit-bearing branches and capsules per plant but highly non-synchronous in tillering and poor in plant type and total seed yield. Thus, the best combiners are mostly Peninsular types. The pooled estimates for specific combining ability effects (s.c.a.) over three different environments are presented in Table 4. It was interesting that crosses involving late parents showed high specific combining ability towards late flowering, whereas crosses with high specific combining ability for early flowering, had either one or both the parents with general combining ability towards earliness. The estimates of specific combining ability were not consistent for the other characters although the performance of some crosses agreed with the expectations on the

basis of general combining ability of their parents, thus giving an indication that non-allelic interactions m a y not be important and prediction of performance on the basis of general combining ability would be generally valid. In general, a comparison of specific combining ability effects had shown that the performance of the crosses M. 10 • Mohaba Local, Wada x Mohaba Local, M. 10 X N.P. (R.R.) 45, Afghanistan-2 x N.P. (R.R.) 45, Mayurbhang • N.P. (R.R.) 9, N. 55 x A.17-t-I and Mayurbhang x A.17-1-1 were exceptionally good. These crosses had one or more Peninsular types or derivatives from them as parents. Thus, the Peninsular material would appear to be promising for exploiting both general and specific combining abilities.

Fractional Diallel Analysis of Combining Ability The analysis of variance of partial diallel pooled over two environments was done for all the seven characters for the cases s -- 9, 7, 5 and 3 (Table 5). For full diallel, s takes the value of ( n - t), where n is the number of parents. The variation due to g.c.a, among the parents was significant in both the years for flowering time, height and height at branching for all values of s,

Combining Ability in Diallel and Fractional Diallel Crosses in Linseed

Vol. 39, No. 2

confirming the results of full diallel that gene action was predominantly additive for these characters, e x c e p t t w o (i.e. n u m b e r of tillers and fruit bearing branches). The pooled estimates of g.c.a, effects for fractional diallel indicated changes in the order of general combining ability effects for all the characters when s was reduced to 3 and the relative values of g.c.a. were overestimated consequently. The results obtained from the serial analysis of fractional diallel were in agreement with the results obtained from the serial analysis of full diallel. The /x,

average variance (gi-gj) increased by more than ten times as s decreased from nine to three indicating

91

that it is not feasible to reduce the fraction of the diall e l w i t h s l e s s t h a n n/2. Variation due to s.c.a, effects with environments were also significant for all values of s for all the characters. The variance ratio specific combining ability • year was less than general combining ability x year for flowering time, height, height at branching and seeds per 5 capsules, when s = 9 and 7 but rapidly w e n t o n i n c r e a s i n g w h e n s d e c r e a s e d t o 5 a n d 3.

Discussion The present study, which was undertaken to examine the nature of gene action and to study the magnitude of genotype • environment interactions

T a b l e 4. Pooled estimates of specific combining ability effects over three seasons Flowering time

Height

Cross

Height at branching

No. of tillers

Pt • PI • PI • 1_'1 • PI • P1 • PI • PI • PI • P2 • P2 • 1'2 • P2 • P2 • P2 • P2 • P2 • P3 • P3 • P3• P3 • P3 • P3 • P3 • P4 • P4 • P4 • P4 • P4 • 1'4 • P5 • P5 • P5 • P5 • 1'5 • P6• P6 • P6 • P6 • P7 • P7 x P7 • P8 • P8 • P9 •

0.00 0.14 2.40 - - 0.67 --2.04 --2.19 --3.11 0.76 2.89 O.94 - - 3.64 7.74 -- 4.35 3.86 0.88 4.02 -- 3 . t 9 0.67 3.48 --2.61 6.23 0.54 O.37 -- 2.40 - - 1.94 - - 1.75 --O.28 --2.12 --3.36 1.25 1.63 - - 1.96 -- 0.79 - - 4.18 9.14 --4.37 3.46 - - 3.90 - - 4.3O - - 1.33 - - 2.50 -- 1.t4 - - t .Ol 2.33 4.76

-- 2.87 1.5o -- 1.93 1.43 2.84 1.52 4.25 t .49 1.65 - - 1.42 - - 1.74 2.06 1.42 3.4t 3.25 1.54 - - 1.12 -- 2.15 t .89 --1.26 4.72 1.49 5.81 -- 0.79 0.76 1143 6.26 --2.97 --1.30 -- 3.84 --0.92 - - 3.49 - - 0.33 7.43 9.38 4.77 -- 4.33 -- 3.43 7.33 - - 1.40 - - 6.22 - - 6.22 " 1.63 --2.80 4.34

- - 3.67 0.38 -- 1.26 - - 2.20 -- t .63 0.55 0.96 - - 0.26 3.10 2.11 - - 2.t 4 --0.97 0.21 --0.65 2.36 - - 1.51 0.13 - - 1.84 2.47 --3.76 3.70 --0.85 O.8O - - 1.62 1.85 - - 1.62 0.96 - - 1.83 --0.42 - - 2.97 - - 1.00 t. 59 1.49 O.40 5.22 4.40 - - 3.50 - - 4.4O --0.29 --O.45 - - 4.24 --4.24 - - 0.48 --2.54 15.60

- - 0.65 1.69 --0.45 0.29 0.78 --0.29 --0.41 0.47 0.16 1.22 O.46 --2.3t 2.21 2.14 - - 0.31 -- 0.77 0.72 0.12 - - 1 .O2 --O.35 - - 1.12 1.24 2.35 0.74 0.92 --0.69 1.8O 0.19 --0.71 - - 1.36 1.00 1.60 - - 0.86 0.86 1.92 --0.39 1.84 0.52 0.76 --0.73 0.03 0.03 0.60 --0.09 1 .I 5

1_'2 P3 I~ P5 P6 P8 P9 P10 P3 P4 P5 P6 P7 P8 P9 P4 P5 P7 P8 P9 Pl 0 P5 P6 P7 P8 P9 Pt0 P6 P7 P8 P9 PIO P7 P8 P9 PI0 P8 P9 PI0 P9 PI0 P10

Fruit bearing branches -- 2.63 3.71 6.77 t 2.79 19.81 --9.08 14.26 11.46 18.38 1.93 3.62 -- 3.75 4.68 35.62 2.40 15.66 -- 6.06 -- 14.20 -- 7.05 --8.16 - - 5.20 - - 7.31 28.92 20.59 2.29 --8.52 33.79 28.01 -- 13.52 3.67 6.75 4.59 - - 5.30 18.22 6.07 10.03 -- 3.41 7.58 20.51 - - 1.91 - - 3.00 6.17 14.52 12.87 1.32

Capsules per plant

Seeds per five capsules

19.46 --25.88 14.60 69.09 42.70 --13.47 --0.97 46.15 -- 50.50 2.78 16.83 -- 11.64 14.98 96.86 13.80 43.84 3.57 -- 5 7 . 5 t --23.81 - - 8.08 -- I0.96 21.61 98.36 63.24 15.25 - - 17.58

- - O. 26 1.53 0.27 - - 1.17 0.91 --1.27 --1.38 -- 2.68 --0.40 --0.91 1.75 --0.5t - - O.35 0.00 - - 1.19 - - 1.20 -- 1.03 O. 15 --0.76 1.17 1.42 O.46 0.17 -- 2.07 0.37 0.31 --2.07 --0.81 --0.83 0.64 -- 1.71 - - 0.79 1.66 I. 34 1.03 t.74 0.82 - - 0.88 - - 1.40 0.19 0.05 0.18 t .73 --0.44 1.72

77.55 83.92 --44.56 2.95 17.00 14.59 - - 20.63 95.20 3.96 49.71 14.16 12.42 7O.90 - - 10.08 - - 19.97 18.03 41.74 26.81 --9.07

P I - - N . I ~. 12; P 2 - - N. 55; P3 -- M.10; P4 - - M a y u r b h a n g ; P5 - - A f g h a n i s t a n - - 2; P 6 - - W a d a ; P7 - - A. 1 7 - - 1 - - t ; P8 - - N.P. (I~.R.) 9; P 9 - - N . P . (R.R.) 45; P 1 0 - M o h a b a local

92

I . J . ANAND and t3. R. MURTY:

Theoret. Appl. Genetics

Table 5. Partial Diallel Analysis of Combining Ability pooled over two seasons for some characters in Linseed Flowering time Source

Replication G.C.A. S.C.A. Year G.C.A. • Y S.C.A. • Y Error

Height

Height at branching

D.F. s=9

7

5

3

9

7

5

3

9

7

5

3

9t.3t 273.77** t75.0t** 6961.50"* 459.72** 330.61"* 40.52

69.23 244.25** 2t3.93"* 501t.70"* 373.t2"* 344-75** 38.35

72.25 168.86"* 241.o6"* 3489.70** 271.55"* 399.27** 38.39

22.56 tt2.95"* 459.6t** 2315.47"* 205.38** 639.70** 37.07

153.04 56t.73"* 348.69** 44t0.90"* 617.0t** 445.02** 48.89

120.77 314.99"* 298.t5"* 3697.60** 369.27** 420.44** 48.t7

50.15 205.69** 3to.79"* 3398.70** 255.44** 4t7.83"* 27.51

7t.55 156.49"* 606.27** t884.20"* 202.30** 622.28** t7.33

54.82 236.96** 138.39"* t493.44"* 278.40** 182.38"* 22.20

42.62 t23.96"* 104.83"* to92.tt** t62.57"* t57.56"* 2t .04

3t.94 78.85** 116.55"* 926.54** tt7.76"* t81.17"* 15.57

47.66 50.77** 2t9.t4"* 666.4t** 77.74** 274.50** t4.66

4 9 35 t 9 35 176

Table 5 (contd.) No. of tillers Source

Replication G.C.A. S.C.A. Year G.C.A. • Y S.C,A. x Y Error

Fruit bearing branches

D.F.

4 9 35 1 9 35 176

9

7

5

3

9

7

5

3

9.89 t.89 N.S. 4.02 N.S. 8.50 N.S. 4.37 N.S. 12.05"* 3.71

t0.90 t.78 N.S. 4.70 N.S. 7.66 N,S. 3.94 N.S. t2.24"* 3.49

5.7i t.47 N.S. 5.50* 3.74 N.S. 4.03 N.S. 14.92"* 3.67

2.68 1.76 N.S. 9.65** 5.52 N.S. 6.36 N.S. 24.35** 4.56

7180.65 495.30 N.S t936.25 N.S 416713.60** 2053.26 N.S 588t.60"* t396.60

5459.98 424.46 N.S 2040.43 N.S 313756.80** 1556.72N.S 6t 55.78** t470.67

71o3.57 34t.52 N.S 2771.69"* 2~1 to5.2o** 1664.65N.S 8245.55** t215.46

2547.67 496.12 N.S 4758.79** 153479.1o** t702.11 N.S tl 093.07** 1219,58

7

5

3

13.77 4.01 N.S 8.67** 2.75 N.S 19.16"* 27.14"* 4.40

t4.26 3.40 N.S 9.27** 2.82 N.S 17.53"* 3t.33"* 4.83

14.23 t.19 N.S 8.14"* 8.04 N.S 9.65* 35.40** 4.20

Table 5 (contd.) Capsules/plant Source

Replication G.C.A. S.C.A. Year G.C.A. x Y S.C.A. x Y Error

Seeds]5 capsules

D.F.

4 9 35 t 9 35 t76

9

7

30608.75 7589.t 5 N.S 20273.87** 4607569.00** 19 566.9t N.S 52315.64** 10680.99

24683.90 39345.92 6554.95N.S 6360.94 N.S 20220.22* 28124.64** 3615425.00** 2757559.00** 14957.55 N.S 15946.55 N.S 54036.t9"* 74249.42** 11667.72 t 9335.72

G.C.A. = General combining ability

5

3

9

11670.65 t973.25 65t9.t8 N.S 47.69 N.S 50832.25** 42.55 N.S 1546770.00** 2357.38** t6687.56 N.S t50.67" 10t619.3t** t23.31" 940t.65 71.t6

S.C.A. = Specific combining ability.

in crosses between parents chosen on the basis of diversity has yielded valuable information. The pooled estimates of combining ability in full dialM have shown t h a t general combining ability was the predominant component for all the characters under study, although variation due to specific combining ability was also significant. I t was interesting t h a t interactions of g.c.a. • years were considerably larger than s.c.a. • years, contrary to the reports b y ROJAS and SPRAGUE (t952) in maize, MATZlNGER, MANN and COCKERHAM (1962) in tobacco and KAMBAL and WEBSTER (1965) in Sorghum. Such divergence in results could be due to the bias in the estimates of combining ability in the presence of maternal and reciprocal effects. Such effects were found to be present in linseed (ANANDand ~V[URTY, under publication). This would be of interest in choosing the maternal parent for developing material with wide adaptation. In the fractional diallel analysis, the relative estimates of general and specific combining ability were similar for s = 9 and 7 but were substantially biased in favour of s.c.a, when s = 3. Similar changes took place in the interaction components also. Therefore, it would appear t h a t limitations on the diversity of parental material and the number of lines included in the diallel could result in incorrect conclusions

t h a t g.c.a, is more stable over environments than s.c.a. The ordering of parents for g.c.a, effects also changed with reduction in the size of the fractional diallel. Since the characters examined are m a j o r yield components, it will be desirable to choose the parental material and number of crosses on the basis of diversity. The best combiners for a majority of the characters are M. tO and N. 55 and are better than the best rust resistent types available. This would indicate the nature of selection in the past m a y have some effect on the combining ability inspite of diversity of their parentage. Genotype • E n v i r o n m e n t Interactions

The d a t a on this aspect had revealed that the pattern of interactions among the parents of different geographical groups was not similar but varied with the character under study. The characters most susceptible to such interactions were capsules per plant, fruit-bearing branches and flowering time in the descending order. Tiller number and seeds per five capsules had shown limited interactions over seasons. The differences among the hybrids were magnified for capsules per plant, fruit-bearing branches and seeds per five capsules as compared to the parents. Although the seasonal effects were

Vol. 39, No. 2

Combining Ability in Diallel and Fractional Diallel Crosses in Linseed

substantial, the parents vs. hybrids comparisons were not significant for four out of the seven characters indicating specific interactions between some parents in both the positive and negative directions. A comparison of the interactions of parents • years and hybrids • years has revealed that the heterozygotes have shown more interactions than the homozygotes for flowering time, height at branching and tiller number and lower interactions for the other four characters. The interactions of parents vs. hybrids • years were substantial for all the characters, thereby indicating that environment could substantially alter the relative performance of parents and hybrids. Therefore there did not appear to be any association between heterozygosity and the capacity of stable performance over different environments. Thus the past history of selection of each character rather than heterozygosity would appear to determine the homeostatic mechanism contrary to that reported b y LERNER (1954), HIESEY (t963) and GRIVrlNG and LANGRIDGE (1963). It is likely that the diversity between parents within the population would be more important for the stability of performance as observed by PEAHLER (1965) in self-pollinated crops like oats. ALLARD and WORKMAN (1963) had considered the optimal conditions might reduce the differences in fitness between homoand heterozygotes. While this could be true under domestication b y man to a considerable degree, the differences in the seasonal conditions in the present study were large enough that the observed results could only be explained on the basis of diversity of the population. Genetic diversity rather than heterozygosity per se might be important for the limited genotype • environment interactions not associated with heterozygosity. Compensatory mechanisms might limit any advantage of the heterozygote in the enzyme activity as observed b y ROWE and ANDREW (1964). Therefore, it would appear possible to get pure breeding lines b y selection for low interactions with environments. The possibility of limited interactions for some characters indirectly influencing yield had indicated that yield improvement would be possible with selection for those traits, particularly in the early growth phase. The results of FINLAY (t963) could also be interpreted on the basis of diversity between the populations responsible for wide adaptation. Among the components of environment, seasonal changes are highly unpredictable and cannot be controlled. As observed in barley by RASMUSSEN and LAMBERT (t96t) and in lima bean by ALLARD and WORKMAN (t963), the variety • year components are large. Therefore, it would be useful to try several environments comparable to the seasonal effects. Variety • year component was reported to be the principal one in rice by NEI (t960) and in upland cotton by AL-JIBoURI et al. (t958). However, as pointed out by MATZINGER,MANN and COCKERHAM (t962), the factors which cause differential varietal

93

response are not those which occur in all years at one location. Therefore, greater significance should be attached to the genotype • year • location component b y increasing the number of locations in two seasons. Such a testing over a wide range was successful in indentifying superior genotypes for hybridization and production of Fl'S and selection of inbreds in self- and cross-pollinated crops like wheat, barley, maize and Sorghum and could be equally useful in linseed.

Acknowledgement The material formed part of a thesis submitted by the Senior author in partial requirements for the degree of Doctor of Philosophy (Ph.D. of Agra Univ., India). Our thanks are due to Sh. V. ARUNACHALAM of Biometrical Genetics Unit, Division of Genetics, Indian Agricultural Research Institute, New Delhi-I 2, for his help in the computer programming.

Zusammenfassung Uber einen Zeitraum yon drei Vegetationsperioden wurde mit einem Material von t0 genetisch verschiedenen Eltern anhand yon vollst~indigen und unvollst~indigen Diallelkreuzungen die Genwirkung bei 7 die Ertrags- und Anpassungsf~ihigkeit von L i n u m usitatissimum L. beeinflussenden Merkmalen gepriift. AuBerdem wurde die Kombinationseignung dieser Merkmale und die Genotyp-Umwelt-Interaktion untersucht. Ein Vergleich der Durchschnittswerte der Eltern und Hybriden an drei verschiedenen Anbauorten ergab positive Heterosis beztiglich der Merkmale H6he, Anzahl der Triebe, samentragende Zweige und Kapseln je Pflanze, negative Heterosis wurde dagegen beztiglich des Merkmals Blfitezeit beobachtet. Die restlichen zwei Merkmale, HShe der Verzweigung und Samenansatz von je 5 Kapseln, zeigten infolge gegenseitiger Aufhebung der Heterosiskomponenten geringe Unterschiede. Eine dreij~hrige Reihenanalyse hinsichtlich der Kombinationseignung nach dem Modell yon GRIFFING (1956) ergab einen signifikanten Einflug des Anbaujahres auf die SchAtzung der Kombinationseignung. Bei den meisten Merkmalen konnte auf additive Wirkung der Gene geschlossen werden, obgleich nichtadditive Wirkung als Folge von spezieller Kombinationseignung bei den Merkmalen fruchtende Sprosse und Kapseln je Pflanze ebenso ausgepr~gt war. Hinsichtlich der allgemeinen Kombinationseignung ftir alle untersuchten Merkmale erwiesen sich die beiden Halbinsel-Sippen, M 10 und N 55, als die besten, gefolgt von P.P. (R.R.) 45 und Mohaba Local. In den unvollst~indigen diallelen Analysen waren die relativen Schiitzungen fiir allgemeine und spezielle Kombinationseignung ftir s --~ 9 und 7 ~hnlich. Wenn s jedoch auf 3 reduziert wurde, ergab sich eine 13bersch~itzung der speziellen Kombinationseignung. Die Reihenanalysen des unvollstiindigen DiallelVersuchs best~itigten die Ergebnisse des vollst~indigen Dialtel-Versuchs. Auch in diesem Fall wurden signi-

94

I. J. ANAND and B. R. MURTY: Combining Ability in Diallel Crosses

f i k a n t e G e n o t y p - U m w e l t - I n t e r a k t i o n e n beztiglich Bltitezeit, H6he, Verzweigungsh6he, f r u c h t e n d e Sprosse u n d K a p s e l n je Pflanze b e o b a c h t e t . Die E r g e b n i s s e d e u t e t e n an, d a b eine V e r r i n g e r u n g des Diallel-Versuchs auf einen Teil m i t s - - - - n / 2 die Reihenfolge u n d G e n a u i g k e i t d e r Schiitzung d e r K o m b i n a t i o n s e i g n u n g beeintritchtigen wtirde. Die A n a l y s e der G e n o t y p - U m w e l t - I n t e r a k t i o n zeigte, d a b die A r t der I n t e r a k t i o n bei den E l t e r n v e r s c h i e d e n e r g e o g r a p h i s c h e r G r u p p e n n i c h t gleich war, s o n d e r n je n a c h d e m u n t e r s u c h t e n M e r k m a l v a r i i e r t e . Betr~ichtliche I n t e r a k t i o n e n w u r d e n ftir die M e r k m a l e K a p s e l n je Pflanze, f r u c h t e n d e Sprosse u n d B l t i t e z e i t - - in dieser Reihenfolge - - b e o b a c h t e t . E i n Vergleich der E l t e r n - u n d H y b r i d e n p o p u l a t i o n e n beztiglich des G r a d e s d e r I n t e r a k t i o n h a t bei allen M e r k m a l e n ergeben, d a b H e t e r o z y g o t i e d u r c h a u s n i c h t u n m i t t e l b a r m i t d e m G r a d d e r H o m e o s t a s i s in B e z i e h u n g zu s t e h e n b r a u c h t . Tats/ichlich w u r d e gefunden, d a b H e t e r o z y g o t e beztiglich Bltitezeit, Verzweigungsh6he u n d Z a h l d e r T r i e b e gr6Bere I n t e r a k t i o n e n u n d ftir die a n d e r e n 4 M e r k m a l e geringere I n t e r a k t i o n e n als H o m o z y g o t e zeigen. Bei d e r M e h r z a h l d e r F 1 - N a c h k o m m e n w u r d e sowohl ftir die v e g e t a t i v e n wie r e p r o d u k t i v e n E i g e n s c h a f t e n ein s i g n i f i k a n t e r EinfluB des A n b a u j a h r e s m i t verschied e n e m D o m i n a n z g r a d auf den G r a d d e r H e t e r o s i s beobachtet. References

t. AI.-JIBOURI, H. A., P. A. MILLER, and H. F. ROBINSON: Genotype and environmentalvariance and covariance in an upland cotton cross of inter-specific origin. Agron. J. 5 o, 6 3 3 - 6 3 6 (t958). - 2. ALLARD, R. W., and P. L. WORKMAN: Population studies in predominantly self-pollinated species. IV. Seasonal fluctuations in estimated values of genetic parameters in limabean populations. Evolution 17, 470--480 (1963). -- 3. ANAND, I. J,, and B. R. MURTY: Performance of heterozygotes in

Theoret. Appl. Genetics

presence of reciprocal and maternal effects in diallel crosses of linseed (Under publication). Indian J. Genet. 28 (1968). -- 4. FINLAY, K . W . : A d a p t a t i o n -- its measurement and significance in barley breeding. Proc. F i r s t Intern. Barley Genet. Symp. Wageningen p. 351--359 (1963). -- 5. GRIFFING, B.: Concept of general and specific combining ability in relation to diallel crossing system. Aust. J. Biol. 9, 463--493 (1956). -- 6.GRIFFING, B., and J. LANGRIDGE: Phenotypic stability of growth in the self-fertilized species Arabidopsis thaliana. Statistical Genetics and P l a n t Breeding NAS-NRC Pub. 982, 368--394 (1963). -- 7. HIESEY, W. M. : The geneticphysiologic structure of species complexes in relation to environment. Proc. l lth. Int. Congr. Genet. Oxford: Pergamon Press 1963. -- 8. JESWANI, L. M., and B. R. MURTY: Conponents of association between some yield factors in linseed. Indian J. Genet. 23, 163--175 (1963). -- 9. KAMBAL, A. E., and O. J. WEBSTER: Estimates of general and specific combining ability in grain sorghum. Crop Sci. 5, 52t--523 (1965). -- 10. KEMPTHORNE, O., and R. N. CURNOW: The p a r t i a l diallel cross. Biometrics 17, 229--256 (t961). -- t l . LERNER, I. M. : Genetic Homeostasis. London: Oliver and Boyd 1954. -- MATZlNGER, D. F., T. J. MANN and C. C. COCKERHAM: Diallel crosses in Nicotiana tabacum. Crop Sci. 2, 383--386 (1962). -13. MURTY, B. R., and I. J. ANAND: Combining ability and genetic diversity in some varieties of Linum usilatissimum. Indian J. Genet.26, 21 -- 36 (1966). -- 14. MURTY, B . R . , V. ARUNACHALAM and I . J . ANAND: Diallel and p a r t i a l diallel analysis of some yield factors in Linum usitatissimum. H e r e d i t y 22, 35--41 ( t 9 6 7 ) . - 15. NEI, M. : Studies on the application of biometrical genetics to p l a n t breeding. Memoirs of the College of Agric., K y o t o U n i v . 82, K y o t o ,

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t6. PFAHLER, P. L.:

Environmental variability and genetic diversity within populations of oats (cultivated species of Avena) and Rye (Secale cereale L.). Crop Sci. 5, 271--275 (1965). --- t 7. RASMUSSEN, D.C., and J. W. LAMBERT: Variety • environment interactions in barley variety tests. Crop Sci. 1, 261--262 (1961). -- 18. ROJAS, B. A., and G. F. SPRAGUE: A comparison of variance components in corn yield trials. I I I . General and specific combining ability and their interaction with locations and years. Agron. J. 44, 4 6 2 - 4 6 6 (1952). - 19. ROWE, P. R., and R. H. ANDREW: Phenotypic stability for a systematic series of corn genotypes. Crop Sci. 4, 563--567 (1964).

Dr. B. R. ]V[URTY, Division of Genetics, Indian Agricultural Research I n s t i t u t e New Delhi t2 (India)

Serial analysis of combining ability in diallel and fractional diallel crosses in linseed.

An analysis of the nature of the gene action for seven characters influencing productivity and wide adaptation in Linum usitatissimum L. was undertake...
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