Genetic analysis of pink bollworm resistance and other quantitative characters in cotton

Generation mean analysis was done by using six parameter model in an interspecific cross between a pink bollworm resistant local variety of Gossypium hirsutum and the highly susceptible variety P.S.H.-1 of G. barbadense by using P sub(1) P sub(2), F sub(2), F sub(2), BC sub(1) and BC sub(2). Mean values of F sub(1) were intermediate between two parents for pink bollworm damage, locules/boll, seeds/boll and fibre length while for seed-cotton yield/plant, bolls/plant and lint index they exceeded the better parent. The F sub(2) means were significantly lower than F sub(1) for pink bollworm damage, seed-cotton yield/plant, bolls/plant, and fibre length, Backcross means were intermediate between F sub(1) and their respective recurrent parent. Scale tests and joint scaling test revealed presence of epistatic interactions for all the characters except for locules/boll. Additive gene effects predominated in the inheritance of most characters followed by dominance gene effects. Additive, dominance and additive x additive gene effects were involved in the inheritance of pink bollworm resistance. For seed-cotton yield/plant, bolls/plant and fibre length epistasis was of complementary type. Duplicate epistasis for pink bollworm damage is suggested to be desirable. Reciprocal recurrent selection method of breeding is suggested for further improvement in resistance and other agronomic characters.