GENETIC VARIABILITY IN COCOON SHAPE, SIZE AND WEIGHT VARIABLES IN MULTlVOLTlNE SILKWORM, BOMBYX MORl. L.

Abstract

Studies on variability estimates, heritability, correlation and path analysis in 56 multivoltine silkworm breeds (Bambyx mario L.) consisting of 46 indigenous and 10 exotics were carried out for cocoon shape, size and weight variables. Wide range of variability for all the characters was observed and the variability was normally distributed except for cocoon volume where it was positively skewed. High heritability coupled with high genetic advance as percentage of mean was observed for cocoon volume and area, rest of the traits exhibited high heritability associated with moderate genetic advance. All the correlations were in positive direction. Cocoon volume and area were significantly associated with other characters. Cocoon width was significantly correlated with cocoon weight and shell weight. Path analysis studies revealed the importance of selection pressure on cocoon width, cocoon volume and shell weight in breeding programme aimed at improving the cocoon weight.