GENETIC ESTIMATES THROUGH NARROW SENSE HERITABILITY FOR SEVEN QUANTITATIVE TRAITS OF THE SILKWORM BOMBYX MORI L.

An investigation was undertaken to study the narrow sense heritability (h2) of eighteen genotypes of the silkworm Bombyx mori viz., six each of bivoltines- C108, Kalimpong-A (KA), NB4D2, CSR2, P31, NB18, multivoltines- Pure Mysore (PM), Nistari, C.nichi, MU1, npnd, Hosa Mysore (HM) and mutants- zebra, ursa, knobbed, pere, lemon and pre drawn from the Germplasm Bank of Department. The scientific method of rearing was followed by analyzing seven quantitative traits viz., larval weight, cocoon weight, cocoon shell weight, cocoon shell ratio, filament length, denier and renditta during three seasons (pre-monsoon, monsoon and post monsoon). The phenotypic co-efficient of variation (PCV), genotypic co-efficient of variation (GCV) and h2 were estimated for the seven of the above said quantitative traits in the eighteen races/breeds and mutants and relevant statistical procedures were utilized to compute the data generated. The data pertaining to the mean values has revealed differential rearing performances of the eighteen races/breeds possibly because of their voltinistic differences. Based on the h2 among six each of bivoltines, multivoltines and mutants, it is evident that the four traits namely larval weight, cocoon weight, denier and renditta recorded moderate h2 values. On the other hand, the traits like filament length, shell weight and shell percentage revealed low heritability values during three seasons of the year. The moderate heritability values recorded by all the races/breeds showed that these characters can be further improved through phenotypic selection in the breeding programme indicating the contributions of additive action of genes and interestingly some of the mutant stocks can be utilized to enhance the selection for the breeding programmes are also herein discussed.