Identification of potential bivoltine breeds of silkworm Bombyx mori L. for silk fibre quality.

摘要

With an objective of selecting suitable parents for silkworm breeding programme for fibre quality 12 oval bivoltine silkworm breeds were evaluated. Data were collected and assessed for five cocoon yield traits and six quality traits of cocoon filament. Analysis of Variance (ANOVA) and multiple trait Evaluation Index methods were employed to study overall performance of the breeds and regression analysis to study the cocoon filament and its size variation. The statistical results revealed that all the breeds performed significantly different indicating the existence of wide variation in the phenotypic traits. CSR2, CSR13 and CSR48 with cumulative evaluation indices of 657.6, 637.9 & 635.1 respectively were ranked as top three breeds. The cocoon filament size (denier) showed marked variations with respect to cocoon layers in different breeds. The denier curve reduced linearly in CSR48, CSR13 and CSR2 by recording higher regression co-efficient (slope-b) values of -0.00049, -0.00089 and -0.00111 respectively. Significant correlations were observed for size variation versus filament length, denier and size differential. Based on the cumulative performances of different traits and considering the filament length and denier as indicators of size variation, which directly influence the uniformity characteristics of raw silk, the genetic stocks CSR2, CSR13 and CSR48 were selected as potential breeding resource materials for breeding tasks aimed at fibre and silk quality improvement.