Combining ability analysis for filament length and some quantitative traits in bivoltine mulberry silkworm (Bombyx mori L.)

Seven-parent diallel analysis in bivoltine mulberry silkworm was conducted to study combiningability in respect of filament length and some quantitative traits. Variances due to both gca and sca were significant for filament length and effective rate of rearing, indicating the importance of additive and nonadditive gene effects. The variances due to reciprocals for filament length, effective rate of rearing, single cocoon weight, and shell ratio were highly significant possibly due to involvement of cytoplasmic factors in the inheritance of these traits. The low X low gea cross, J122 X Howlok, showed overall good specific combination for maximum expression of the traits, indicating overdominant type of gene action. The parents involved in the best cross belong to closely divergent clusters.