Özet:

Information on estimates of combining ability and heritability of the promising lines of breeding material is important for evolving higher yielding varieties of rapeseed (Brassica napus L.). To estimate the combining ability and heritability of F2 populations of 4 x 4 full diallel crosses and parents, an experiment was carried out at The University of Agriculture, Peshawar, in growing season 2012-2013. Four parental lines and F2 populations of six direct and six reciprocal crosses were planted in the experiment using randomized complete block design. Data were recorded on yield and yield components. Analysis of variance revealed significant variation among genotypes for all the parameters studied. Yield plant-1 ranged from 4.27 to 9.17 g, pods main- raceme-1 ranged from 42 to 89 and seeds pod-1ranged from 8 to 18. Among parents highest yield plant-1 and seeds pod-1were observed for AUP-402. Cross AUP-402 x AUP-401 produced the highest seed yield plant-1 and more pods plant-1. The results of combining ability analysis showed that general combining ability was significant at p ≤ 0.01 for pods main-raceme-1and seeds pod-1. SCA and reciprocal effects were significant at p ≤ 0.01 for pods main-raceme-1, seeds pod-1 and seed yield. Genotype AUP-401 was best general combiner for several parameters. Crosses AUP-403 x AUP-404 and AUP-401 x AUP-402 were best specific combiners for seed yield plant-1. Heritability (bs) estimates were high (>70%) for seeds pod-1. Moderate heritability values were observed for seed weight and seed yield plant-1. The variance components of specific combining ability (SCA) were greater than respective general combining ability (GCA) components of all the characters signifying the presence of non-additive genetic effects in transfer of these traits and for that reason selection in the later generations should be practiced for improvement of these traits.

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