Heritability and Genetic Advance as Selection Indicators for Improvement in Cotton ( Gossypium hirsutum L.)
ABSTRACT The investigation pertaining to heritability and genetic advance in cotton genotypes for some quantitative and qualitative traits were undertaken. The results indicated highly significant differences among the parents and F1 crosses for all the traits. Plant height and seed cotton yield per plant displayed moderate to higher estimates of heritability and genetic advance which is indicative of additive with partial dominance type of gene action suggesting the feasibility of selection in the early generation, while bolls per plant, boll weight and staple length exhibited moderate to high heritability and low genetic advance which indicated over dominance type of gene action thereby revealing that selection might be useful if delayed. The traits monopodia and sympodia per plant gave low to moderate heritability and low genetic advance but the trait micronaire value manifested high heritability coupled with low genetic advance.
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ABSTRACT: The leaf area, petiole length and seed cotton yield were measured in six generations of a cross between cotton (Gossypium hirsutum L.) varieties (namely, NuCOTN-35B & NIAB-111) to study the genetic mechanisms controlling these characters, and to examine the relationship among them during 2002-2004. Five parameter models, m, (d), (i), (j), (l) for leaf area, while m, (d), (h), (i), (j) for petiole length and seed cotton yield were found adequate for genetic analysis. Genetic analysis through generation means for leaf area (cm 2 ) indicated that this trait is controlled by the genes acting additively and complicated by (additive × additive) (i), (additive × dominance) (j) and (dominance × dominance) (l) interactions. The genetic analysis of the data for petiole length (cm) and seed cotton yield (g) revealed that both additive and dominance gene effects controlled these two traits. Potence ratio was greater than unity for leaf area and petiole length, showing over-dominance for them. For seed cotton yield, the potence ratio of 0.75 revealed partial dominance. Narrow sense heritability for leaf area (0.80), petiole length (0.62) and seed cotton yield (0.71) was moderate, suggesting the chances for improving these characters through selection from the segregating populations. Strong positive associations among the three traits suggest that indirect selection for these photosynthetic activity-enhancing traits would be helpful in improving seed cotton yield in cotton.01/2008;