COMBINING ABILITY ANALYSIS OF SILK YIELD ATTRIBUTES IN BIVOLTINE SILKWORM BOMBYX MORI L.

Studies on the combining ability, nature and extent of different gene actions; involving 7 x 7 diallel set of Bivoltine silkworm (Bombyx mori L) were carried out for thirteen traits viz. Total larval duration; 5th age larval duration; weight of mature larvae, cocoon yield by Number and cocOon yield by weight, single cocoon weight, single shell weight, shell ratio, pupation rate, average filament length and weight, raw silk recovery and denier. Analysis of variance revealed sigrificant difference in parents, for total larval duration, 5th age larval duration, single cocoon weight, shell ratio, Raw silk recovery, in hybrids for total larval duration, 5th age larval duration, cocoon yield by number, cocoon yield by weight, denier and parents vs hybrids for total larval duration, 5th age larval duration, weight of mature larvael. Cocoon yield by number, cocoon yield by weight, pupation rate, average filament length, average filament weight and raw silk recover/ except for few traits indicating presence of considerable variability in the materials understudy. Mean squares due to gea revealed significant difference for all the traits except weight of mature Irvae, shell weight, pupation rate average filament length, average filament weight and denier. None of the parents was found to be a good general combiner for all the traits. SKUAST-27, SI<UAST-28, SKUAST-29, SKAU-R-1 and NB4D2 were found to be good general combiners for many* economically important traits. No cross was found to be good specitic combiner for all the traits while SKUAST-29 x SKAU-R-I, SKAU-R-1 x SKAU-R-6 and SKUAST-27 x SKAU-R-l were found to be good specific combiners for five viz, average filament length, average filament weight and raw silk recovery & single shell weight and shell ratio out of the thirteen traits.