Genetic Variance Components in Cotton by Generation Mean Analysis

Abstract

The mode of gene action for the expression of quantitative traits is decided by the predominance of variances due to additive, dominance and epistasis gene effects. In this experiment, involving four F1 crosses (TCH1716 x TCB37, TCH1705-101 x TCB209, KC2 x TCB26 and TSH0250 x DB3) of upland cotton, inheritance of major yield components by Generation Mean Analysis was investigated. The investigation revealed that both additive and dominance gene effects were involved in the expression of most of the yield contributing traits. One or more types of epistatic interaction effects were prevalent for all the characters and thus played a major role in the control of the characters. The inheritance of the traits was found to be complex in lieu of the low heritability estimates and genetic advance over mean. For seed cotton yield per plant, the dominance x dominance interaction effect was positively significant for all the crosses, the additive x dominance effect was positively significant only in cross 1 and the dominance main effect showed negative significant in all crosses. The dominance (h) and dominance x dominance (l) effects were of opposite signs in all the crosses indicating the presence of duplicate epistasis in all the crosses. To harness additive gene effects for improvement of some of the traits, breeding methods with postponement of selection to later generation should be adopted.