Heterosis and combining ability analysis in Tetraploid Cotton (G.hirsutum and G.barbadense L.)

The present investigation was carried out with a view to study the heterosis, combining ability and gene action for seed cotton yield, yield attributing traits, ginning outturn and important fibre quality parameters in tetraploid cotton (G.hirsutum L. and G.barbadense L.). A set of 31 genotypes consisting of 21 (HxB) hybrids, seven lines of G. hirsutum, three testers of G. barbadense and one check hybrid DCH 32was grown at Rasi Seeds Research and Development Farm, Attur. The hybrids were developed adopting Line x Testermating design. Analysis of variance showed significant differences among the parents and hybrids for all the characters indicating presence of genetic variability. Combining ability analysis indicated that both additive and non additive gene effects were important in the inheritance of all the traits. The ratio of variance due to GCA to that of SCA was less than one for all the character under study indicating importance of dominance gene effects in the inheritance of these characters. The parents CG 64 (hirsutum),CG67 (hirsutum) and CG45SB (barbadense) were good general combiner for the seed cotton yield per plant and number of bolls per plant.CG 45SB was also a good combiner for the 2.5 per cent span length.The cross CG 64 x CG 45 SB recorded the highest per se performance and standard heterosis for seed cotton yield. Two crosses viz., CG64 x CG45SB and CG67 x CG45SB registered significant per se performance,positive scaeffects along with significant positive standard heterosis for seed cotton yield and majority of yield components and fibre quality traits.