Combining Ability and Heritability Studies for Yield Contributing Traits in F_2 Populations of Brassica napus

摘要

The present study was undertaken to approximate combining ability and broad sense heritability in F2 populations of diallel crosses of Brassica napus L. at the University of Agriculture, Peshawar during growing season 2012-13. Data were recorded on various yield and yield related traits i.e. primary branches plant~(-1), pods main raceme~(-1), pods plant~(-1), seeds plot~(-1), 1000-seed weight and seed yield plant~(-1). Breeding material comprised four parental genotypes along with their 12 F_2 populations. Analysis of variance exhibited significant (PsO.01) differences among the genotypes for all the studied traits. On the basis of mean performance, parental genotype G6 was good general combiner for pods main raceme~(-1), primary branches plant~(-1), pods plant~(-1), seeds plot~(-1) and 1000-seed weight, while G9 had the highest GCA for seed yield plant~(-1). The cross G2 x G4 was the best specific combiner for primary branches plant~(-1), seeds plot~(-1) and seed yield plant~(-1), while populationG4 x G6 showed maximum SCA for pods main raceme~(-1) and pods plant~(-1). Broad sense heritability estimates for studied traits were high for pods plant 1 (0.63), primary branches plant~(-1) (0.68), 1000-seed weight (0.74), seed yield plant~(-1)(0.80) and seeds plot~(-1) (0.96) while moderate for pods main raceme~(-1) (0.44), suggesting the effectiveness of selection of these traits in different generations. Most of the crosses with positive SCA effects for yield components had at least one of parentswith positive GCA effects.