Evaluation of heterosis in five sets of desi cotton hybrids.

Sixty eight desi cotton hybrids were developed by crossing 30 genotypes selected from five groups of Gussypium arboreum races bengalense and indicum and G. herbaceum. In each group, 15 hybrids were created by diallel mating (without reciprocals). Interspecific crosses between two varietics each of G. arboreum races bengalense and indicum were also made with two G. herbaceum strains obtaining eight hybrids. Studics indicated that interspecific crosses exhibited higher magnitude of useful heterosis for seed cotton yield as compared to the intra racial hybrids tested in four groups. Negative heterosis for ginning out turn and halo length was shewn by interspecific crosses. Intra racial hybrids of red x red (G. arboreum race bengalense) varieties also expressed higher magnitude of heterosis effect for seed cotton yield. Dwarf x dwarf hybrids expressed high heterosis for yield and halo length, but negative heterosis for ginning out turn. Crosses within the race indicum registered substantial heterosis for all characters under study.