Estimation of heritability and components of variation for various characters in Gossypium hirsutum L. genotypes
2002
Iqbal, M.A.
The Studies involving the complete set of 4 x 4 diallel crosses were conducted The genetic analysis of the characters was performed through diallel cross experiment following Hayman (1954a, 1954b) and Jinks (1954). The graphic representation of variance (Vr) and covariance (Wr) shows that traits like plant height, number of monopodial branches per plant, number of sympodial branches per plant, number of bolls per plant, height of first opened boll, seed cotton yield, lint percentage, staple length, and fibre fineness were controlled by overdominance type of gene action, while fibre strength as governed by additive type of gene action with partial dominance. However, non-allelic interactions were absent for characters, suggesting that epistasis was not involved in the expression of these traits. Overdominance type of gene action might be considered when heterosis is to be exploited in cotton improvement programme. The conclusion from the studies is that heritable genetic variation, albeit of very low level, exists in the parent material. The genetic effects seems to be fixed and crosses between relatively diverse parent are needed to create variation for further selection and breeding. Nevertheless, overdominance expression for the study yield and quality traits suggests potential for the exploitation of heterosis in the material.
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