Analysis of heterosis in some bivoltine silkworm hybrids of Bombyx mori L
Kritika Sharma and Kamlesh Bali
The investigation was carried out during spring 2018, to rear six parents and thirty-one hybrid combinations including control by involving full diallel set of bivoltine breeds in a complete randomized design (CRD) to identify the high yielding bivoltine silkworm hybrids. Thirty-one treatments including control were replicated thrice with 200 worms per replicate post III. Moult. For all the thirty hybrids, estimates for heterosis were worked out as per cent deviation from mid parent value. Different hybrids combinations exhibited significant and desirable heterotic estimate at egg, larval, cocoon and post cocoon stages when compared to check hybrid. Six hybrids viz. ND2 × NSP, ND2 x U1, ND2 ×JD6, ND3 × ND2, ND3×JD6 and NSP ×JD6 recorded positive heterosis for egg traits. For larval traits, eight hybrids viz., ND2 × CSR2, ND3 × NSP, ND3 × CSR2, ND3 × JD6, U1 × JD6, CSR2 × ND2, CSR2 × ND3 and JD6 × ND2 were found to be heterotic. For commercially important cocoon parameters like coon yield by weight, by number, good cocoon and pupation percentage, significant heterosis was observed in twenty-three hybrids. Only one hybrid i.e. CSR2 ×ND3 exhibited heterosis above than control for single cocoon weight, single shell weight and shell ratio percentage. At post cocoon stage, only three hybrids viz. NSP × ND3, NSP × U1 and CSR2 × ND2 were significantly heterotic. The perusal of data on the basis of cumulative positive heterosis value of different traits revealed that, hybrid ND2 × NSP (353.36) ranked at 1st position followed by CSR2 × ND2 (333.17) and NSP × ND3 (333.15) at number 2nd position and 3rd position respectively and were shortlisted and found promising for exploitation at commercial level after validation by having multi location trial before releasing in the field.