UTILIZATION OF BIVOLTINE FEMALE PARENTS FOR PREPARATION OF CROSS BREEDS OF BOMBYX MORI L. FOR THE TROPICS

The performance of 25 hybrids involving 5 multivoltine and 5 bivoltine lines was studied to find out the nature and extent of heterosis during May-June-the most adverse commercial season of Eastern India. Marked better and mid parent heterosis was observed in most of the crosses for most of the commercial characters. Better heterosis in absolute silk content, considered as yield, ranged from2.67% to 140.47%. A total of 5 out of 6 yield components viz. ERR No. ERR Wt. SCW, SSW and filament length showed better parent heterosis in most of the crosses, while no appreciable heterosis could be noticed for fecundity and S.R.96. The hybrids were ranked on the basis of evaluation index value and NBus X CBs has screened out as the best hybrid for commercial use followed by NB18 X G. P5.X. CB5, KS(O) X B and NB18 X G. The merits of the study are also discussed.