EVALUATION OF SOME BIVOLTINE SILKWORM (Bombyx mori L.)

Loading...
Thumbnail Image
Date
2003
Journal Title
Journal ISSN
Volume Title
Publisher
SKUAST Kashmir
Abstract
The Jammu and Kashmir is the only traditional bivoltine belt in the country and produces quality bivoltine silk. However, among other reasons, lack of productive silkworm breeds/hybrids has come in the way of boosting cocoon production in the state.Moreover, the parental stocks of particular hybrids lose their potential due to continuous inbreeding. As such some new silkworm breeds specific for spring season were evolved at Division of Sericulture, Mirgund. Rearing in other seasons is practically feasible and essential to boost cocoon production and to increase the economic viability of Sericulture in Jammu and Kashmir state. This necessitates the synthesis/identification of season specific breeds/hybrids. The need for having different breeds/hybrids for different environmental conditions arises because of variations in quality of feed and other input factors. In the present study, 26 bivoltine silkworm (Bombyx mori L.) genotypes were evaluated under two different environments (spring and summer) and it was found that no genotype displayed a significantly superior performance vis-à-vis check breeds in all the metric traits. However, several genotypes registered this type of performance in several sub-sets of traits. Based on the evaluation index values 14 and 13 genotypes possessed considerable potential in spring and summer respectively. Estimates of components of genetic variance were higher in magnitude for all the traits studied except denier and fecundity in summer than in spring. Major portion of phenotypic variance was due to genotype. All the traits displayed high heritability (above 80%) accompanied with reasonable genetic advance. The estimates of genotypic correlation coefficients were higher in magnitude than corresponding estimates of phenotypic correlation coefficients in both the environments. Based on the results obtained it could be concluded that the environment had a significant contribution in the performance of genotypes. The breeds C122, Yakwei, CSR4 and Sannish-M are best for spring rearing season, while as the breeds KA, SKUAST-7, Sannish-M and SKUAST-23 for summer rearing season. The genotypes SKUAST-7, SKUAST-8, SKUAST-23, SKUAST-24, C122, Haulak, Jam 21, J112, Sannish-M, Yakwei, KA and CSR4 should be regarded as stable genotypes. Improvement, in the 12 metric traits studied, through simple phenotypic selection would be effective. In the present study, weight of matured larvae, single cocoon weight, cocoon yield/10,000 larvae by number, pupation rate, denier, raw silk recovery (%) and fecundity in E1 and weight of matured larvae, single cocoon weight, single shell weight, raw silk recovery (%), cocoon yield by number and pupation rate in E2 exhibited a significant positive correlation with cocoon yield /10,000 larvae by weight. Hence simultaneous selection of these traits will improve the silk yield and help in the amelioration of deteriorated breeds.
Description
M.Sc Thesis submitted to SKUAST Kashmir
Keywords
BIVOLTINE SILKWORM, SILKWORM, Bombyx mori L., Sericulture
Citation
Collections