Abstract:

Twenty two BIPs (biparental progenies) generated from two bivoltine silkworm (Bombyx mori L.) hybrids, viz., SH^₆ × NB^₄D^₂ and CSR^₂×CSR^₄, were evaluated for their performance in seven metric traits (weight of 10 mature larvae, single cocoon weight, single shell weight, shell ratio (%), effective rate of rearing, yield/10 000 larvae (wt.) and filament length. The experiment was laid out in a completely randomized design (CRD) with three replications for each treatment. The aim was to short list promising progenies and to work out estimates of direct selection parameters like heritability and genetic advance so that the generated information is utilized for the formulation of effective breeding and selection procedures aimed at extraction of new and more productive genotypes. BIPs 2, 4, 5, 6, 7, 10, 14, 16, 19 and 20 displayed a significantly superior performance in several traits. Single cocoon weight, yield/10 000 larvae (wt.) and filament length exhibited moderate estimates of heritability and reasonable genetic gains indicating genotypic variability to be a major component of phenotypic variability; hence, scope exists to bring about improvement in these traits through simple phenotypic selection. The rest traits (weight of 10 mature larvae, single shell weight, shell ratio (%) and ERR) recorded moderate estimates of heritability and low genetic gains environmental variability to be a major component of phenotypic variability; hence, selection for these traits would be less effective.
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Key words: Bombyx mori, biparental progenies, heritability, genetic gain