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Genetic analysis of phenological traits and grain yield in durum wheat under normal and late sown environments

S.N. Sharma and R.S. Sain

All India Coordinated Wheat and Barley Improvement Project, Rajasthan Agriculture University, Agricultural Research Station Durgapura- Jaipur 302 018, Rajasthan, India, E-mail: snsarsdgprjpr@yahoo.com

Abstract

Generation means analysis was performed using means of twelve generations viz., P1, P2, F1, F1, B1, B2, B1s, B2s, B11, B12, B21 and B22. A trigenic interaction model was found adequate to explain the inheritance of all the traits studied except days to heading (normal sown) and plant height. Both additive (d) and dominance (h) gene actions were equally important in controlling days to maturity and plant height. Epistatic effects particularly trigenic interactions were predominant in most of cases over digenic interactions as well as over additive and dominance effects. However, digenic interactions had a significant role in controlling characters studied. Duplicate type of epistasis was observed in days to maturity under normal sown and plant height under both the environments. Absolute totals of non-fixable gene effects were much higher than fixable in both the environments, indicating the greater role of non-additive gene effects. Additive x additive x dominance (x), and dominance x dominance x dominance (z) were the major components causing significant heterosis. Restricted recurrent selection or selective diallel mating methods of hybridization can provide better opportunity for improvement of the traits in durum wheats.

Introduction

Recently, durum wheat has received proper attention of geneticists and breeders resulting in gathering of information on the nature and magnitude of gene effects governing the inheritance of various quantitative traits. The experimental evidences clearly indicated that earliness is desirable in durums for the crop to escape terminal heat stress in the warmer areas of central India. Similarly, medium maturity and dwarfness in durums are also preferable to harvest higher grain yield under high input management conditions, particularly in north India. Hence, there is a need to find out the inheritance pattern of earliness and dwarfness in durums for further tangible advancement in specific areas of adaptation. The present study endeavours to determine this inheritance pattern.

Materials and methods

The experimental material was generated from a single cross HI 8062 x JNK-4W-128 that involved two diverse parents. Twelve basic generations of this cross were developed that included HI 8062 as P1, JNK-4W-128 as P2, F1 and F2, first backcross generations (BC1 and BC2) with both parents, selfed progenies of first backcross (BC1 F2, BC2 F2) and second backcross generations i.e. the BC1 and BC2 plants again crossed with both original parents (BC1 x female parent; BC1 x male parent and BC2 x female parent; BC2 x male parent). All these populations were raised together in randomized block design with three replications at 30cm x 10 cm spacing under normal (25th November) and late (25th December) sown environments in the same cropping season at Agricultural Research Station, Durgapura, Jaipur, Rajasthan, India. Each parent and F1 generation was sown in 2 rows, each backcross generation in 4 rows and F2 and the second cycle of backcrosses in 6 rows of 5 m length. Observations on days to heading (when 75% plants in the plot headed), day to maturity (when 75% plants in the plot matured), plant height (cm) and grain yield per plant (g) were recorded on 15 random plants in each parent and F1, 30 plants in each backcross generations and 60 plants in each F2 and second backcross generations in each replication. The data for each population in both environments were analyzed separately by joint scaling test of Cavalli (1952) to determine the nature of gene action. Components of heterosis in the presence of digenic (Jinks and Jones, 1958) and trigenic interactions were calculated as suggested by Hill (1966).

Results and discussion

The generation means analysis indicated that subsequent fitting of different models, 10-parameter models were found adequate to account for the differences among the generation means for days to heading, maturity and grain yield in both plantings, except for days to heading under late sown condition where a 6-parameter interaction model was found more appropriate. In delayed sowings, the character expression is affected, such that the difference in the mean values between different generations is reduced. This ultimately affects the estimates of genetic components as well as subsequent fitting of the different models. On the other hand for plant height even 10-parameter model did not adequately fit the data, indicating involvement of more complex interactions or linkage in the inheritance of plant height. However, the various gene effects were estimated on the basis of 10-parameter model. The results of joint scaling tests confirmed the role of non-allelic interactions in controlling the traits studied in both the sowing environments (Table 1).

Table 1. Results of joint scaling test and gene effects in cross HI 8062 x JNK-4W-128 of durum wheat over environments

Effects

Days to heading

Days to maturity

Plant height (cm)

Grain yield (g/pl)

Normal sown

Late
sown

Normal sown

Late
Sown

Normal sown

Late
sown

Normal sown

Late
sown

m

80.36**
0.70

72.83**
0.49

116.50**
0.96

115.21**
0.75

71.44**
0.86

69.19**
1.05

10.16**
1.20

10.25**
1.18

(d)

0.86
0.67

0.10
0.31

5.95**
0.76

1.91**
0.62

-22.62**
0.72

-7.79**
0.86

-0.59
0.94

-2.02
1.04

(h)

-1.01
1.34

1.18
0.77

-5.01**
1.53

-3.76**
1.25

18.90**
1.46

8.14**
1.73

4.48*
1.88

-0.78
2.09

(i)

4.62**
1.32

2.43**
0.77

15.00**
2.54

5.03**
1.95

-16.47**
2.17

-8.92**
2.49

11.35**
3.34

-2.06
2.57

(j)

-1.03
3.02

-2.30**
0.78

-9.18*
3.32

0.23
3.12

0.35
3.48

31.78**
3.76

-8.41
4.61

2.04
4.85

(l)

14.79*
6.13

-0.09
1.66

52.19**
9.17

-13.24
6.79

-77.72**
8.12

-93.46**
10.21

12.32
11.82

-12.05
10.90

(w)

-2.43
2.72

 

-17.38**
2.89

-3.31
2.10

25.84**
2.85

-7.47*
3.37

-7.43*
3.59

-0.26
4.03

(x)

21.22**
6.54

 

61.78**
11.25

-21.37*
8.52

-94.90**
9.49

-98.11**
12.17

28.22
14.38

-15.55
12.57

(y)

10.09
7.22

 

38.78**
6.45

15.53*
6.90

-69.96**
8.51

81.45**
7.74

5.42
11.06

6.48
10.48

(z)

29.58**
10.18

 

-49.02**
14.18

33.63**
12.95

77.33**
13.92

153.91**
15.41

5.63
19.49

41.07*
17.82

χ2 for 10 parameter model

1.10 (2)

 

4.69 (2)

5.38 (2)

40.84 (2)

200.12 (2)

4.64 (2)

2.82 (2)

*, ** Significant at 0.05 and 0.01 levels, respectively; Degree of freedom

The analysis of gene effects revealed that both additive (d) and dominance (h) gene actions were equally important in the expression of days to maturity and plant height. However, none of the main effect was found significant for days to heading and grain yield (late sown) indicating an important role of epistatic interactions in controlling the inheritance in both the environments. Among the digenic epistatic interactions (i-l, Table 1) one or other interactions were found significant for all the traits except grain yield (late sown), however, their relative magnitude and signs changed with change in sowing environment. Additive x additive (i) and dominance x dominance (l) interactions significantly contributed maximum for all the traits under normal sown condition except grain yield, where only additive x additive (i) interaction significantly contributed. Results further exhibited under late sowing condition, additive x additive (i) for days to heading and days to maturity and additive x dominance (j) and dominance x dominance (l) for plant height significantly contributed more in controlling the inheritance. But their relative magnitude and signs changed with change in sowing environments. As a matter of fact, when sowing is delayed, the genotypic expression is affected, hence the possibility is that the true phenotypic differences are not resolved leading to observation of non-significant differences between the different genetic parameters estimated in normal and delayed sowings. In such situations estimates made in late sowings are found to be non-significant to less significant in comparison to normal environments, unless the parents involved are specially selected for the targeted environment. Among trigenic epistatic interactions (w-z, Table 1) one or other of the parameters were found significant in both the environments for all the four traits under study except days to heading under late sown condition. Additive x additive x dominance (x) and dominance x dominance x dominance (z) significantly contributed the most towards controlling the inheritance of all traits except for days to heading in late sowing (Table 1).

Table 2. Absolute totals of epistatic effects, fixable and non-fixable gene effects in cross HI 8062 x JNK-4W-128 of durum wheat over environments

Character

Environment

Main effects

Absolute totals of epistatic interactions

Absolute totals of gene effects

(d)

(h)

I order

II order

Fixable

Non-fixable

Days to heading

Normal

0.86

-1.01

20.44

63.32

7.92

77.71

Late

0.10

1.18

4.83

-

2.53

3.58

Days to maturity

Normal

5.95

-5.00

76.38

166.95

38.33

215.96

Late

1.91

-3.76

18.49

73.84

10.25

87.76

Plant height

Normal

-22.62

18.90

94.56

268.02

64.93

339.16

Late

-7.79

8.14

134.17

340.93

24.18

466.85

Grain yield

Normal

-0.60

4.49

32.09

46.72

19.32

64.51

Late

-2.02

-0.79

16.16

63.38

4.35

77.99

[(i), (j), (l), (w), (x), (y), (z)]; [(d), (i), (w), (h), (j), (l), (x), (y), (z)]

The generation means analysis further revealed that absolute totals of epistatic effects were higher than the main effects. Second order interactions (absolute totals) were much higher than the first order interactions in both the environment for all the four traits except days to heading under late sown condition, where first order interactions (absolute totals) had high value indicating its important role in controlling the inheritance of this trait. Thus it is clear, that trigenic interactions were responsible for controlling the inheritance of almost all the traits studied (Table 2). Singh and Nanda (1989), Walia et al. (1995) and Katiyar and Ahmed (1996) also reported a greater role of epistasis in controlling the inheritance of these traits. The parameter (h), (l) and (z) were significant and differed in signs, indicating duplicate epistasis at three gene level in days to maturity (under normal sown) and plant height (both the sowing environments). A conclusion regarding the type of epistasis could not be drawn in days to heading and maturity (under late condition) and grain yield because either (h) and (l) or both parameters were non-significant.

Absolute totals of non-fixable gene effects were higher than fixable gene effects in both the environments, indicating a greater role of non-additive gene effects in the inheritance of all the four traits under study (Table 2). Singh and Paroda (1987), Singh and Nanda (1989), Mann and Sharma (1995), Menon and Sharma (1997) and Sheikh et al. (2000) also reported that non-additive type of gene effects were responsible for the inheritance of these traits in durum wheat.

Thus, the study revealed that non-additive gene actions were more important than additive gene actions in the expression of these traits. Hence, methods, which exploit non-additive gene action, such as restricted recurrent selection or selective diallel mating system could hold promise for genetic improvement of these traits. Furthermore, as the duplicate type of epistasis was observed in days to maturity and plant height, so the selection intensity should be mild in the earlier and intense in the later generations to achieve the desirable improvement in these traits in durums.

References

Cavalli LL (1952) An analysis linkage in quantitative inheritance. In: Reeve EC and Waddington CH (ed) Quantitative inheritance. Her Majesty’s Stationery Office, London: 135-144.

Jinks JL and Jones RM (1958) Estimation of components of heterosis. Genetics 43: 223-234.

Katiyar PK and Ahmed Z (1996) Detection of epistasis components of variation for yield contributing traits over two environments in bread wheat. Indian J Genet 56: 285-291.

Mann MS and Sharma SN (1995) Combining ability in the F1 and F2 generations for diallel cross in macaroni wheat. Indian J Genet 55(2): 160-165.

Menon U and Sharma SN (1997) Genetic of yield determining factors in spring wheat over environments. Indian J Genet 57(3): 301-306.

Singh I and Paroda RS (1987) Partial diallel analysis for combining ability in wheat. Indian J Genet 47(1): 1-5.

Singh G and Nanda GS (1989) Estimation of gene action through triple test cross in bread wheat (T. aestivum L.) Indian J Genet 59(11): 700-702.

Sheikh S, Singh I and Singh J (2000) Inheritance of some quantitative traits in bread wheat (T. aestivum L. em. Thell). Ann Agric Res 21(1): 51-54.

Walia DP, Dawa T, Phaha P and Choudhary HK (1995) Gene effects controlling grain yield and its components in bread wheat (T. aestivum L.). Agric Sci Digest 15 (3): 129-131.

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