GENETIC ANALYSIS OF PINK BOLLWORM RESISTANCE AND OTHER QUANTIATIVE CHARACTERS IN COTTON

Abstract

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 Pl, P2, Fl, F2, BCl and BCz. Mean values of Fl were intermediate between two parents for pink bollworm damage, loculeslboll, 'seedslboll and fibre length while for seed-cotton yield/plant, bolls/plant and lint index they exceeded the better parent. The Fz means were significantly lower than Fl for pinkbollwormdamage,seed-cottonyield/plant, bolls/plant, and fibre length. Backcross means were intermediate between Fl and their respective recurrent parent. Scale tests and joint scaling test revealed presence of epistatic interactions for all the characters except for loculeslboll. 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, bollstplant 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.