LINE-X TESTER ANALYSIS OF COMBINING ABILITY IN NEW GENOTYPES OF BIVOLTINE SILKWORM (BOMBYX-MORI)

A line x tester analysis was carried out, involving 8 newly evolved ge notypes, 2 testers and 16 hybrids of bivoltine silkworm (Bombyx mori L ,.) for assessing the combining ability in respect of cocoon yield by number and weight, single-cocoon weight, single-shell weight, shell ra tio (%) and filament length. All the characters studied were controlle d by additive but predominantly by non-additive gene action. 'CNR 14' with positive general combining ability (gca) effect for all the 6 cha racters studied proved the best general combiner, followed by 'CNR 12' and 'CNR 13' for 5 characters, 'CNR 15' for 4 characters and 'CNR 16' for 3 characters. 'CNR 13' and 'CNR 16' for single-cocoon weight, 'CN R 12', 'CNR 14' and 'CNR 16' for single-shell weight, 'CNR 12' and 'CN R 15' for shell ratio (%) and 'CNR 14' for filament length were found to be the best general combiners with highly significant positive gca effects. 'CNR 16' x 'NB 4D2' was considered the best hybrid, as it rec orded significant effects of specific combining ability (sea) for 3 ch aracters out of the 6 studied.