VARIABILITY, GENETIC COMPONENTS AND SELECTION RESPONSE IN SEGREGATING GENERATIONS AMONG SOME COTTON CROSSES

Abstract

The successful breeding program depends on genetic variability response to selection, heritability and genetic advance. The present investigation aimed to estimate these components in two intra-specific cotton crosses (Giza 92 x Giza 87 and Giza 96 x Giza 87) during early segregating generation. Most of the studied traits showed high broad sense heritability coupled with low or moderate genetic advance as percent of mean in F2 generation. So, these traits controlled by non additive gene action. The analysis of variances for F3 families showed highly significant differences between F3 families and variance within F3 was lower than among families for all the studied traits over the two crosses. All F3 families had low intra-class correlation values over the two crosses, so selection between families is better than within families. The additive genetic variance was larger than dominance variance for all the studied traits except for seed cotton yield / plant and lint %, also, these traits showed partial degree of dominance for cross I. While, cross II has higher values of dominance genetic variance than additive variance for all traits except for boll weight and fiber length, so that showed overdominance. Selection differential and response to selection were found to be positive for all traits during F2 and F3. The probability of new recombinant lines falling outside parental range was higher in cross I than cross II for all traits except for boll weight and fiber length. The study reveals that judicious selection leads to improvement in next generation.