Genetic basis of some quantitative traits in upland cotton (Gossypium hirsutm L.)

Five cotton cultivars were crossed in a complete diallel to study the inheritance of different polygenic traits. Genotypic differences were found to be significant (P<0.01) for all the characters. Adequacy tests disclosed that data of all the parameters were fully adequate for genetic analysis except bolls per plant, staple length, fibre strength, and fibre fineness, which was partially or not adequate. Additive component of genotypic variation (D) was significant and predominant for plant height, sympodia per plant, staple length and fibre strength, while dominance effects (H1 and H2) were main controlling factors for of monopodia per plant, number of bolls, lint percentage and seed cotton yield. More dominant genes were revealed in the parents for sympodia per plant, lint percentage and seed cotton yield. The values of heritability in narrow sense (h2 n.s) and H2/4H1 demonstrated asymmetrical and unequal distribution of dominant genes in parents for all characters. Plant height, sympodia per plant, staple length and fibre strength exhibited high narrow sense heritability (h2 n.s) due to the presence of additive gene action, whereas, monopodia per plant, number of bolls, lint percentage and seed cotton yield possessed low heritability. The genetic analysis suggested that plant height, sympodia per plant, staple length and fibre strength could be improved through sib family, pedigree and progeny selection, while exploitation of heterosis would be necessary to attain the genetic advancement in monopodia per plant, number of bolls, lint percentage and seed cotton yield.