Magnitude of heterosis for economic traits in newly developed single hybrids of Silkworm, Bombyx mori L.

Abstract

Abstract An investigation was conducted in India using the parental stock breeds among the six bivoltine tester and five multivotine line strains of the silkworm Bombyx mori L., to estimate heterosis expressed in single cross hybrids with respect to important economic traits. In terms of mean value performance, testers CSR50 and GEN2, and line BL67, showed the most promise, while the F1 hybrid BL67 × GEN2 produced the highest shell weight, cocoon-shell percentage and maximum cocoon-filament weight. Other superior hybrids were BL24 × GEN2 for single cocoon weight, PM × GEN2 for cocoon filament length and HM × CSR17 for denier. For each trait in the hybrid combination, different heterotic effects were noted. Based on heterosis, hybrid BL67 × GEN2 was optimal for cocoon-shell ratio and single shell weight; PM × GEN2 for cocoon filament length and weight; PM × CSR16 for single cocoon weight; and BL24 × CSR5 for Denier. The majority of the hybrids outperformed the BL67 × CSR5 standard check variety. For all the characters studied collectively, no one hybrid outperforms the others. In general, the traits studied exhibited a greater degree of heterosis in their crosses. The overall analysis unequivocally demonstrates that future breeding programs will use the high-yielding lines and testers that were identified as potential breeds for the synthesis of superior multi × bivoltine hybrids for tropical conditions.