05. Genetic analysis of yield and yield related attributes in Brassica napus
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Abstract
Diallel analysis in Rapeseed (Brassica napus L.) was carried out during 2011-2012 at The University of Agriculture, Peshawar to estimate the pattern of inheritance and heritability for important traits. During 2010-2011 four contrasting genotypes of Brassica napus. viz. G2, G4, G6 and G9 were crossed in a diallel manner and in the following season (2011-2012) all the F1 hybrids along with parents were evaluated under field condition in a randomized complete block design. Highly significant (P ≤ 0.01) differences were observed for plant height, primary branches plant-1, seeds pod-1, pods plant-1, weight of 1000 seed, seed weight plant-1. Additive-dominance model was fully adequate for plant height, primary branches plant-1, pods plant-1, seeds pod-1, whereas for the rest of the traits it was partially adequate. Diallel analysis showed significant additive (a) and dominance (b) variances for all parameters. Genetic parameters estimation showed significant and higher magnitude of dominance component for all the studied traits. Graphical analysis showed overdominance for all of the parameters. The value of average degree of dominance for plant height (1.858), primary branches plant-1 (4.355), pods plant-1 (3.704), seeds pod-1 (2.417), 1000 seed weight (3.995) and seed weight plant-1(1.852) also indicated the presence of overdominance gene action controlling these yield attributes, as it was greater than one. Low narrow (0.16-0.31) and broad (0.81-0.96) sense heritabilities were estimated for all the studied parameters, suggesting the low value of additive gene action and genetic potential for the improvement of such traits through selection in later generations.
Keywords: Diallel analysis, Inheritance studies, Rapeseed