EVALUATION OF GENETIC VARIANCES, HERITABILITIES, AND CORRELATIONS FORYIELD AND FIBER TRAITS AMONG COTTON F2 HYBRID POPULATIONS

F-2 hybrid cultivars continue to occupy a small portion of the cotton (Gossypium hirsutum L.) production area in the United States, but occu py a larger proportion of the production area in some other countries. Sixty-four F-2 hybrids resulting from crosses of four commercial cult ivars and 16 pest-resistant germplasm lines were evaluated for five fi ber and four yield traits in four environments at Mississippi State, M S. An additive-dominance genetic model was employed for these traits. The minimum norm quadratic unbiased estimation (MINQUE) method was use d with a mixed model approach for estimating genetic variance and cova riance components and for predicting genetic correlations. This study investigated genetic variances, heritabilities, and genetic and phenot ypic correlations between agronomic and fiber traits among these 64 F- 2 hybrid populations and discussed the usefulness of these populations for use as hybrids or for selections for pure lines. Dominance varian ce accounted for the major proportion of the phenotypic variances for lint yield, lint percentage, and boil size indicating that hybrids sho uld have an advantage for these traits compared to pure lines. A low p roportion of additive variance for fiber traits and the significant ad ditive x environment variance components indicated a lack of substanti al useful additive genetic variability for fiber traits. This suggests that selections for pure lines within these F-2 populations would hav e limited success in improving fiber traits. Genetic and phenotypic co rrelation coefficients were of comparable magnitude for most pairs of characters. Fiber strength showed a positive additive genetic correlat ion with boil weight. Dominance genetic correlations of fiber strength with elongation and 2.5% span length were also significant and positi ve; however, the additive genetic correlation of length and strength w as zero.