Scholarly article on topic 'Line × tester analysis in rapeseed: Identification of superior parents and combinations for seed yield and its components'

Line × tester analysis in rapeseed: Identification of superior parents and combinations for seed yield and its components Academic research paper on "Biological sciences"

CC BY-NC-ND
0
0
Share paper
Academic journal
Open Agriculture
OECD Field of science
Keywords
{""}

Academic research paper on topic "Line × tester analysis in rapeseed: Identification of superior parents and combinations for seed yield and its components"

Research Article

Open Access

Valiollah Rameeh

Line x tester analysis in rapeseed: Identification of superior parents and combinations for seed yield and its components

DOI: 10.1515/opag-2016-0012

received June 1, 2016; accepted September 9, 2016

Abstract: The objectives of this research were to investigate the genetic structure of the 20 F1s rapeseed hybrids established from five female moderate maturing lines and four early maturing male testers, determine parents showing general combining ability (GCA) and assess crosses demonstrating specific combining ability (SCA). Significant mean squares of lines and testers determined GCA and confirmed the presence of additive genes that were influencing the traits, while the significance of linex-tester interactions indicated the importance of SCA of parents and demonstrated the importance of dominance or non-additive genetic effects. Significant variance of parents vs. crosses revealed significant average hetero-sis for all the traits except first pod height and seeds per pod. High narrow-sense heritability estimates for number of branches and pod length indicated the importance of additive genetic effects for these traits. Significantly positive correlation was exhibited between GCA effects on pods on main raceme and seed yield and, therefore, the GCA effect on pods on main raceme can be used as indirect selection criterion for improvement of seed yield. The crosses L41xFoma2, ZafarxR42 and L22BxR38 recorded significant positive SCA effects and high mean values of seed yield of 3400, 3311.3 and 2904.2 kg ha-1, respectively.

Keywords: genetic variation, heritability, line seed yield

tester,

Corresponding author: Valiollah Rameeh, Agronomic and Horticulture Crops Research Department, Mazandaran Agricultural and Natural Resources Research and Education Center, AREEO, Islamic Republic of Iran, E-mail: vrameeh@gmail.com

1 Introduction

The oilseed Brassicas is the world's third most important source of oils and its production has steadily increased through conventional and modern plant breeding approaches [1]. Seed yield of rapeseed is a quantitative trait that has low heritability, in most case, and is largely influenced by different environmental conditions [2-6]. Similar observations have been recorded in several row and vegetable crops [7-9]. Genetic variability in any crop species is considered to be critical for genetic improvement in seed yield along with other economically important characteristics [10-13]. Inter and intra Brassica species crosses are appropriate ways to make genetic variations and develop the new varieties [14, 15]. In rapeseed breeding program, magnitude of general and specific combining ability effects (GCA and SCA) are important indicators of the potential of inbred lines in hybrid combinations; hence, in developing hybrid and open pollinated varieties. The information on combining ability is important for selecting parent-plants, understanding the nature of gene actions involved, introgressing elite traits, and maximizing yield. The variance for GCA includes the additive section of the total variance, while that for SCA comprises the non-additive portion of the total variance that is arising largely from dominance and epistatic deviations [16-18]. Information and exact study of combining ability can be useful in regard to selection of breeding methods and selection of lines for hybrid combination [19, 20]. Due to the various theoretical and practical advantages of this technique, in recent years the choice of parental forms on the basis of combining ability has been extended. Genetic gain of Brassica requires definite information concerning the nature of combining ability of parents available for use in the hybridization program. Most of previous studies on combining abilities have shown significant GCA and SCA effects for yield and its component characters. These results indicate that both additive and non-additive gene action are important in the inheritance of these traits [21-24]. Variation in performance of yield indicated that

Ip 2016 Valiollah Rameeh published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License. Unauthenticated

Download Date | 5/15/17 11:23 AM

the inheritance patterns of yield varies with the genetic material and climatic vagaries that warrant to explore the genetic information about the parent material before making the selections. Since different genetic materials exhibit different genetic parameters, the objectives of the present study were to examine the combining ability patterns of selected rapeseed (Brassica napus L.) genotypes in a linextester analysis and assess genetic parameters of yield and yield components to determine superior candidates for promising hybrid cross combinations.

2 Materials and methods

Five moderate-maturing of spring rapeseed (Brassica napus L.) genotypes including 'L41', 'Zafar', 'L56', 'L31' and 'L22B' as lines were crossed with four early-maturing genotypes including 'Foma2', 'R42', 'R41' and 'R38' as testers in linextester crossing scheme between 2010 and 2011. Eighteen F1's along with their parents were grown in a randomized complete block design with three replications at Baykola Agriculture Research Station, located in Neka, Iran (53°, 13' E longitude and 36* 43' N latitude, 15 m above sea level) during the winter of 2012/2013. Each plot consisted of four rows 5 m long and 40 cm apart. The distance between plants in each row was 5 cm resulting in approximately 300 plants per plot, which was sufficient for F1 genetic analysis. The soil was classified as a deep loam (Typic Xerofluents, USDA classification) and contained an average of 280 g of clay kg-1, 560 g silt kg-1, 160 g sand kg-1, and 22.4 g organic matter kg-1 with a pH of 7.3. Soil samples were found to have 45 kg N ha-1 (mineral N in the upper 30-cm profile). Fertilizers were applied at the rates of 100: 50: 90 kg ha1 of N: P: K, respectively. All plant protection measures were adopted to make the crop insect free. Seed yield (adjusted to kg ha-1) was recorded based on two middle rows of each plot. The data were recorded from 10 randomly competitive selected plants of each entry of each replication for first pod height, number of branches, pods on main raceme, pods per plant, pod length, and seeds per pod. Data for the genotypes were subjected to linextester analysis to estimate GCA and SCA effects [22]. Lines and testers were treated as female and male parents, respectively, during crosses. A i-test was used to test whether the GCA and SCA effects were different from zero. Narrow-sense heritability estimates of the traits and Pearson coefficient correlation among the traits were calculated.

3 Results and discussion

3.1 Linextester analysis of variance

Linesxtester analyses were performed on all the traits for those crossed genotypes that showed significant differences. Results of these analyses are summarized in Table 1. Significant differences were found among the treatments, parents and their crosses for first pod height, number of primary branches, pods on main raceme, pods per plant, pod length, seeds per pod, and seed yield, thus indicating sufficient genetic variations for the genotypes and their cross combinations for these traits (Table 1). For all the traits, except pod length, genetic variations among the lines were greater than the testers. The lines had significant genetic diversity for all the traits. However, no significant genetic difference was recorded by the testers for pods on main raceme and seeds per pod. Parents vs crosses mean squares, which indicate average heterosis, were significant for all the traits except first pod height and seeds per pod. High narrow-sense heritability estimates were found for number of branches, pod length and seeds per pod, indicating the prime importance of additive genetic effects for these traits. High narrow-sense her-itability estimates for some of yield components in rape-seed have been reported in earlier studies [2, 26, 27].

3.2 Means performances and general combining abilities of the parents

The mean values of the parents including lines and testers for all the traits are presented in Table 2. Among the testers, first pod height varied from 97.8 to 108.6 cm in genotypes 'R38' and 'R42', respectively. Among the lines, first pod height ranged from 88.38 to 115.59 cm in genotypes 'L31' and 'L41', respectively. The GCA and SCA genetic effects are presented in Table 3. Two parental genotypes 'R38' and 'L31' had significantly high negative GCA effects on first pod height and, therefore, reduced effects for this trait in their cross combinations. Number of branches had less variation than the other traits in parental lines. Genotypes 'Foma2' and 'Zafar' with 5.20 and 5.22 branches per plant, respectively, had high mean values for this trait. Significantly positive correlation of GCA effects was detected between number of branches and pods per plant, which makes it possible to use the GCA effect on this trait as an indirect selection criterion for improvement of pods per plant (Table 4). Pods on main raceme ranged from 46.7 to 49.6 in testers and it varied from 41.98 to 54.82

Table 1: Analysis of variance (ANOVA), narrow-sense heritability and component of variability for yield components and seed yield of rape-seed (Brassica napus L.) genotypes based on line x tester method

Source of variance df First pod Number Pods on Pods per Pods Seeds per Seed yield

height of main plant length pod

branches raceme

Replication 2 774.8** 2.95** 383.4** 11.1 0.97 198.0** 1203007.4**

Treatment 28 778.0** 1.63** 348.6** 1889.8** 1.29** 30.2** 391951.8**

Parents 8 642.9** 1.90** 682.6** 990.7** 1.64** 33.0** 621857.3**

Parents vs crosses 1 25.3 2.13* 47.8** 4893.1** 1.34** 2.1 412194.1*

Crosses 19 874.5** 1.49** 223.8** 2110.3** 1.14** 30.5** 294084.1**

Lines 4 1341.5** 2.22** 396.3** 2484.1** 1.27** 48.2** 295939.5**

Testers 3 297.7* 2.62** 23.5 1515.9** 2.40** 18.0 151393.5

Line x tester 12 863.0** 0.97** 216.4 2134.3** 0.79** 27.8* 329138.2**

Error 56 84.2 0.44 28.2 142.4 0.31 8.5 65305.6

Heritability 0.15 0.82 0.31 0.19 0.80 0.50 0.05

Variations due to lines 32.30 31.37 37.28 24.78 23.45 33.27 21.19

Variations due to testers 5.38 27.76 1.66 11.34 33.24 9.32 8.13

Variations due to lines x testers 62.33 41.12 61.07 63.88 43.77 57.57 70.69

Significant at p<0.05 and 0.01, respectively

Table 2: Means of parents for yield components, seed yield

First pod Number Pods on Pods per Pods Seeds per Seed yield

Parents height (cm) of branches main raceme plant length (cm) pod (kg ha-1)

1-Foma2 104.3 5.2 49.6 154.4 7.0 25.0 2799.9

Testers 2-R42 108.6 4.5 47.3 131.5 6.6 25.0 2791.7

3-R41 103.0 4.3 48.2 146.9 6.7 24.1 2755.2

4-R38 97.8 4.4 46.7 137.9 6.0 22.7 2585.1

5-L41 115.59 4.96 54.82 159.41 6.62 26.66 2977.92

6-Zafar 110.32 5.22 52.32 154.28 6.32 22.63 2762.00

Lines 7-L56 98.47 4.43 41.98 128.26 6.98 24.02 2611.38

8-L31 88.38 4.28 42.46 143.10 6.20 21.89 2581.25

9-L22B 104.33 4.28 48.08 128.34 6.79 25.68 2732.21

LSD (a=0.05) 14.98 1.08 8.67 19.49 0.91 4.76 417.31

LSD (a=0.01) 19.93 1.44 11.53 25.92 1.21 6.33 555.02

In each a probability level, LSD is related to lines and testers

in female lines. The GCA effect on pods on main raceme had a significantly positive correlation with GCA effect on seed yield, which makes this trait a suitable indicator of good combiner genotypes for seed yield. Significantly positive correlation between pods per plant and seed yield justified the favorable genotypes were 'Foma2', 'L41' and

'Zafar' as they recorded high mean values of pods per plant. High narrow-sense heritability (0.80) estimated for pod length, indicated the prime importance of additive genetic effects for this trait. Genotypes 'Foma2' and 'L56' with significantly positive GCA effects on pod length are good candidates for improving pod length.

Table 3: Estimates of GCA effects for yield components and seed yield and oil of rapeseed (Brassica napus L.) genotypes based on linextester fashion

First pod Number Pods on Pods per Pods Seeds per Seed yield

Parents height of main plant length pod (kg ha-1)

(cm) branches raceme (cm)

1-Foma2 0.9 0.63** 1.65 11.73** 0.42** 0.81 66.93

Testers 2-R42 5.16* -0.12 -0.66 -11.16** 0.03 0.81 58.71

3-R41 -0.39 -0.3 0.24 4.23 0.09 -0.12 22.23

4-R38 -5.67* -0.18 -1.23 -4.77 -0.54** -1.50* -147.84*

5-L41 12.18** 0.33 6.90** 16.74** 0.03 2.49** 244.98**

6-Zafar 6.9 0.60** 4.38** 11.61** -0.27 -1.53 29.04

Lines 7-L56 -4.95 -0.21 -5.94** -14.43** 0.39* -0.15 -121.59

8-L31 -15.03** -0.36 -5.46** 0.42 -0.39* -2.28** -151.71*

9-L22B 0.9 -0.36 0.15 -14.34** 0.21 1.5 -0.75

S.E. GCA (tester) 2.37 0.17 1.37 3.08 0.14 0.75 65.98

S.E. GCA (line) 2.65 0.19 1.53 3.44 0.16 0.84 73.77

*/**Significant at p<0.05 and 0.01, respectively

Table 4: Pearson coefficients of correlation estimates among the means, GCA effects of parent and SCA effects of the crosses for yield components and seed yield

Means (n=20)

Traits First pod Number Pods on Pods per Pods Seeds per Seed

height of branches main raceme plant length pod yield

First pod height 1

Number of branches 0.05 1

Pods on main raceme 0.01 0.52* 1

Pods per plant 0.08 0.45* 0.57** 1

Pods length 0.31 0.06 0.31 -0.16 1

Seeds per pod 0.15 0.24 0.34 0.13 0.51* 1

Seed yield 0.16 0.23 0.46* 0.70** -0.02 0.23 1

GCA (n=9)

Traits First pod Number Pods on Pods per Pods Seeds per Seed

height of branches main raceme plant length pod yield

First pod height 1

Number of branches 0.55 1

Pods on main raceme 0.87** 0.70* 1

Pods per plant 0.38 0.75* 0.71* 1

Pods length 0.25 0.15 0.20 -0.12 1

Seeds per pod 0.65* 0.18 0.52 0.07 0.67* 1

Seed yield 0.88** 0.60 0.86** 0.58 0.36 0.79* 1

SCA (n=20)

Traits First pod Number Pods on Pods per Pods Seeds per Seed

height of branches main raceme plant length pod yield

First pod height 1

Number of branches 0.62** 1

Pods on main raceme 0.59** 0.40 1

continued Table 4: Pearson coefficients of correlation estimates among the means, GCA effects of parent and SCA effects of the crosses for yield components and seed yield

Pods per plant Pods length Seeds per pod Seed yield

0.26 0.34 0.54* 0.01

0.21 -0.19 0.31 -0.01

-0.48* 0.19 0.22 0.26

-0.26 0.15 0.76**

0.36 -0.32

Significant at p<0.05 and 0.01, respectively

Table 5: Means of the crosses for yield components and seed yield

First pod Number of Pods on Pods per Pods Seeds per Seed yield

Crosses height branches main plant length Pod (kg ha-1)

(cm) raceme (cm)

1-L41 x foma2 104.33 5.0 61.6 171.5 7.0 24.9 3400.0

2-L41 x R42 83.67 5.4 57.4 161.9 6.1 23.8 3000.0

3-L41 x R41 98.00 4.6 47.2 153.5 6.7 28.2 2908.3

4-L41 x R38 76.00 4.8 53.1 150.7 6.6 29.7 2603.3

5- Zafar x Foma2 114.00 6.1 54.4 146.0 6.4 22.2 2512.5

6- Zafar x R42 83.67 4.9 44.8 172.7 6.3 23.1 3311.3

7- Zafar x R41 74.00 5.1 64.8 176.5 6.8 24.2 2975.0

8- Zafar x R38 70.67 4.8 45.3 121.9 5.8 21.1 2249.2

9-L56 xFoma2 98.33 5.7 51.4 171.4 7.7 29.8 2847.5

10-L56 x R42 83.67 4.1 45.7 104.9 7.2 25.1 2695.8

11-L56 x R41 85.67 3.9 35.6 96.1 7.4 22.1 2196.7

12-L56 x R38 89.33 4.0 35.3 140.6 5.6 19.1 2705.5

13-L31 x Foma2 112.33 4.4 44.0 171.6 6.9 22.4 2511.7

14-L31 x R42 83.33 3.6 33.8 111.6 6.1 24.7 2537.5

15-L31 x R41 81.33 4.8 46.7 165.6 5.5 22.7 2812.5

16-L31 x R38 83.00 4.3 45.4 123.6 6.3 17.8 2463.3

17- L22B x foma2 117.00 5.1 36.5 111.6 7.1 25.6 2727.7

18-L22B x R42 98.00 4.5 54.7 106.4 7.2 28.3 2413.7

19- L22B xR41 117.00 3.1 46.7 142.7 6.9 23.2 2883.3

20- L22B xR38 116.00 4.3 54.4 152.6 6.0 25.7 2904.2

LSD (a=0.05) 14.98 1.08 8.67 19.49 0.91 4.76 417.31

LSD (a=0.01) 19.93 1.44 11.53 25.92 1.21 6.33 555.02

3.3 Means performances and specific combining abilities of the crosses

The genetic variation of linesxtesters crosses for all the traits were beyond lines and testers (Table 1). Hybrid performance was generally better than parental performance for all the traits except number of branches (Table 5). Mean values of first pod height ranged from 70.67 to 117.1 cm in crosses 'Zafar'x'R38' and 'L22B'x'R41', respectively. Most of the crosses with high mean values of first pod height had at least one parent with high mean value for this trait. The cross combinations with low mean value of first

pod height trait including 'Zafar'x'R38', 'Zafar'x'R41' and 'L31'x'R41' are preferred because high mean value of first pod height is more susceptible to lodging. Seven out of 20 crosses had significant SCA effects on first pod height (Table 6). High narrow-sense heritability estimates and the role of additive genetic effects on first pod height were estimated, and the results showed that most of the crosses did not have any significant SCA effect on this trait. The crosses 'Zafar'x'Foma2' and 'L56'x'Foma2' had high mean value of first pod height trait. Pods on main raceme differed from 33.8 to 64.8 in crosses 'L31'x'R42' and 'Zafar'x'R41', respectively. Significantly positive correlation of SCA effects was determined between pods on main raceme and

Table 6: Estimates of SCA effects for yield components and seed yield of rapeseed (Brassica napus L.) genotypes based on line x tester fashion

First pod Number of Pods on Pods per Pods Seeds per Seed yield

Crosses height branches main plant length Pod (kg ha-1)

(cm) raceme (cm)

1-L41 x foma2 -13.77* -0.6 5.1 0.39 -0.06 -2.58 355.17*

2-L41 x R42 10.92* 0.6 3.24 13.71 -0.51 -3.66* -36.63

3-L41 x R41 1.83 0.01 -7.86* -10.11 0.03 1.65 -91.8

4-L41 x R38 0.99 0.03 -0.48 -3.96 0.51 4.59** -226.74

5- Zafar x Foma2 -2.58 0.24 0.45 -20.04** -0.36 -1.2 -316.41*

6- Zafar x R42 -8.73 -0.21 -6.87* 29.55** -0.03 -0.39 490.62**

7- Zafar x R41 17.73** 0.24 12.21** 18.03* 0.39 1.65 190.77

8- Zafar x R38 -6.42 -0.27 -5.79 -27.57** -0.03 -0.06 -364.98*

9-L56 xFoma2 29.07** 0.66 7.74* 31.41** 0.24 4.95** 169.2

10-L56 x R42 -1.95 -0.21 4.38 -12.15 0.24 0.3 25.74

11-L56 x R41 0.39 -0.21 -6.66* -36.36** 0.36 -1.83 -436.92**

12-L56 x R38 -27.51** -0.24 -5.46 17.13* -0.84* -3.42* 241.98

13-L31 x Foma2 -4.02 -0.54 -0.12 16.74* 0.3 -0.33 -136.5

14-L31 x R42 -3.03 -0.54 -8.01** -20.37** -0.09 1.98 -102.48

15-L31 x R41 -1.86 0.87* 3.99 18.33** -0.81* 0.96 209.04

16-L31 x R38 8.91 0.21 4.14 -14.67* 0.6 -2.61 29.94

17- L22B x foma2 -8.73 0.24 -13.17 -28.47** -0.15 -0.84 -71.31

18-L22B x R42 2.79 0.36 7.26* -10.74 0.39 1.77 -377.13*

19- L22B xR41 -18.06** -0.87* -1.65 10.14 0.03 -2.4 129.03

20- L22B xR38 24.00** 0.24 7.59* 29.07** -0.27 1.5 319.95*

S.E. (SCA) 5.30 0.38 3.07 6.89 0.32 1.68 147.54

Significant at p<0.05 and 0.01, respectively

seed yield, which indicate that the SCA effect on this trait can be used as an indirect selection criterion for seed yield improvement. Crosses 'Zafar'x'R41' and 'L41'x'Foma2' had high mean performances of pods on main raceme. Pods per plant was positively correlated with seed yield, which indicated that the crosses 'Zafar'x'R41', 'L41'x'Foma2', 'Zafar'x'R42', 'L56'x'Foma2' and 'L31'x'Foma2' with high mean value of this trait were good combinations for pods on main raceme. Most of the crosses with high mean value of pods per plant resulted from the parental lines with high mean value of this trait. Pod length was more affected by additive effects; therefore, most of the crosses did not have significant SCA effects on pod length. The crosses 'L41'x'Foma2', 'L56'x'Foma2', 'L56'x'R41', 'L56'x'R38', 'L22B'x'Foma2' and 'L22B' x'R42' with high mean values of pods length were more favorable combinations. The crosses 'Zafar'x'Foma2' and 'L56'x'Foma2' with significantly positive SCA effects on seeds per pod were good combinations. Seven out of 20 crosses had significant SCA effects on seed yield. The crosses including 'L41'x'Foma2', 'Zafar'x'R42' and 'L22B'x'R38' with significantly positive SCA effects on seed yield had also high mean value of seeds per pod. Previous studies on combining abilities have shown significant GCA and SCA effects on yield and

its component characters. These results indicated that both additive and non-additive gene actions were important for the inheritance of seeds per pod [21-23].

4 Conclusion

In general pods, on main raceme and pods per plant were positively correlated with seed yield, indicating that these traits can be used as selection criteria for seed yield improvement. Parents vs crosses mean square as indicator of average heterosis was significant for all the traits except for first pod height and seeds per pod. Hybrid performance was generally better than parental performance for all the traits, except for number of branches. The genetic variations of linesxtesters for all the traits were more than lines and testers. Among the yield components, numbers of branches and pod length were more heritable than the others. In the case of the traits with low narrow-sense heritability, the results suggest that more emphasis on specific crosses followed by selection in progenies rather than pursuing GCA by mass selection should be given.

Acknowledgements: The author wishes to thank Agricultural and Natural Resources Research Centre of Mazandaran and Seed and Plant Improvement Institute

References

[1] Sabaghnia N., Dehghani H., Alizadeh B., Mohghaddam M, Diallel analysis of oil content and some agronomic traits in rapeseed (Brassica napus L.) based on the additive,dominance genetic model, 2010, Australian Journal of Crop Science,4: 609-616

[2] Diepenbrock W., Yield analysis of winter oilseed rape Brassica napus L.): A review. Field Crops Research, 2000, 67: 35-49

[3] Habekotte B., Evaluation of seed yield determining factors of winter oilseed rape (Brassica napus L.) by means of crop growth modeling. Field Crops Research, 1997, 54: 137-151

[4] Rameeh V., Combining ability and factor analysis in F2 diallel crosses of rapeseed varieties, 2010, Plant Breeding and Seed Science, 62: 73-83

[5] Wang J.S., Wang X.F., Zhang Y.F., Zhang Z., Tian J.H., Li D.R., Study on heterosis among subspecies or varieties in B. campestris L. Proceedings of the 12th International Rapeseed Congress Wuhan, (TRCW'07), 2007, China: Science Press USA, PP: 108-110

[6] Zhang G., Zhu W., Genetic analyses of agronomic and seed quality traits of synthetic oilseed Brassica napus produced from interspecific hybridization of B. campetris and B. Oleracesea, 2006, Journal of Genetics, 85: 45-51

[7] Dia M., Wehner T.C., Arellano C. 2016. Analysis of genotype x environment interaction (GxE) using SAS programming. Agron. J. 108 (4) doi: 10.2134/agronj2015.0503

[8] Dia M., Wehner T.C., Hassell R., Price D.S., Boyhan G.E., Olson S., King S., Davis A.R., Tolla G.E. 2016. Genotype x environment interaction and stability analysis for watermelon fruit yield in the U.S.. Crop Sci. 56 (4): 1645-1661. doi: 10.2135/ cropsci2015.10.0625

[9] Dia M., Wehner T.C., Hassell R., Price D.S., Boyhan G.E., Olson S., King S., Davis A.R., Tolla G.E. 2016. Values of locations for representing mega-environments and for discriminating yield of watermelon in the U.S. Crop Sci. 56 (4): 1726-1735. doi: 10.2135/cropsci2015.11.0698

[10] Inamullah H., Ahmad F., Mohammad S., Hassan G., Gul R., Evaluation of the heterotic and heterobeltiotic potential of wheat genotypes for improved yield, 2006, Pakistan Journal of Botany, 38(4): 1159-1168

[11] Mahmood T., Ali M., Iqbal S., Anwar M, Genetic variability and heritability estimates in summer mustard( Brassica juncea), 2003, Asian Journal of Plant Sciences, 2 (1): 77-79

[12] Rameeh V., Cherati A., Abbaszadeh F., Salinity effects on yield, yield components and nutrient ions in rapeseed genotypes, 2012, Journal of Agricultural Science, 57(1): 19-29

[13] Wang X., Hua W., Liu G., Liu J., Yang Q., Wang and H., Genetic analysis on oil content in rapeseed (Brassica napus L.), 2010, Euphytica, 173, 17-24

(SPII) for providing genetic materials and facilities for conducting the experiment.

[14] Amiri Oghan H., Fotokianb M.H., Javidfar F., Alizadeh B., Genetic analysis of grain yield, days to flowering and maturity in oilseed rape (Brassica napus L.) using diallel crosses, 2009, International Journal of Plant Production, 2: 19-26

[15] Qian, W., Sass O., Meng J., Li M., Frauen M., Jung C, Heterotic patterns in rapeseed (Brassica napus L.): I. Crosses between spring and Chinese semi,winter lines, 2007, Theoretical and Applied Genetics,115: 27-34

[16] Malik S.I., Malik H.N., Minhas N.M., Munir M, General and specific combining ability studies in maize, 2004, International Journal of Agriculture and Biology, 6:856-859

[17] Teklwold A., Becker H.C., Heterosis and combining ability in a diallel cross of Ethiopian mustard inbred lines, 2005, Crop Science, 45: 2629-2635

[18] Variath M.T., Wu J.G., Li Y.X., Chen G.L., Shi C.H., Genetic analysis for oil and protein contents of rapeseed (Brassica napus L.) at different developmental times, 2009, Euphytica, 166, 145-153

[19] Nassimi A.W., Raziuddin Sardar A., Naushad A, Study on heterosis in agronomic characters of rapeseed (Brassica napus L.) using diallel, 2006, Journal of Agronomy, 5: 505-508

[20] Rameeh V., Heritability and other genetic parameters assessment for flowering associated stress indices in oil seed rape varieties, 2011, International Journal of Plant Breeding and Genetics, 5(3): 268-276

[21] Akbar M., Tahira B.M., Hussain M., Combining ability studies in Brassica napus L. International Journal of Agriculture and Biology, 2008, 10:205-208

[22] Huang, Z., Laosuwan P., Machikowa T., Chen Z., Combining ability for seed yield and other characters in rapeseed. Suranaree Journal of Science and Technology, 2010, 17: 39-47

[23] Singh M., Singh L., Srivastava and S.B.L, Combining ability analysis in Indian mustard (Brassica juncea L. Czern and Coss), 2010, Journal of Oilseed Brassica, 1 (1): 23-27

[24] Yadav Y.P., Prakash R., Singh R., Singh R.K., Yadav J.S., Genetics of yield and its component characters in Indian mustard (Brassica juncea (L.) Czern and Coss.) under rainfed conditions, 2005, Journal of oilseeds research, 22, 255-258

[25] Mather K., Jinks J.L, Biometrical Genetics, 3rd edn. Chapman and Hall, London

[26] Rehman A.U., Ali M.A., Atta B.M., Saleem M., Abbas A., Mallahi A.R, Genetic studies of yield related traits in mungbean (Vigna radiata L. Wilczek), 2009, Australian Journal of Crop Science, 3: 352-360

[27] Wang H.Z., The potential problems and strategy for the development of biodiesel using oilseed rape. Chinese Journal of Oil Crop Sciences, 27:74-76