همبستگی فنوتیپی صفات اقتصادی پیله کرم ‌ابریشم با استحکام نخ ابریشم

The economic traits of silkworm cocoon and silk filament are polygenic and, like the quantitative traits, the performance of each trait may change due to interactions between them. Therefore, in silkworm breeding, it is necessary to pay attention to the correlation between important economic traits to evaluate the selection responses. In the present study, the phenotypic correlation between silkworm cocoon economic traits including performance of each box, good cocoon weight, number of good cocoons, number and weight per liter, cocoon weight, cocoon shell weight, cocoon shell percentage and pupal mortality percentage with silk filament strength traits included specific tension and elongation percentage were measured. Research data for six commercial silkworm hybrids included four Chinese hybrids Baiyue × Qiufeng (BQ), Qiufeng × Baiyue (QB), 872 × 871, 871 × 872, and two Iranian hybrids 151 × 154 and 154 × 151, respectively Which were bred under controlled temperature, humidity and standard conditions. The results showed that the phenotypic correlation between filament strength traits and all cocoon traits except number per liter was negative. Phenotypic correlation between elongation percentage and cocoon traits was not significant (P> 0.05). Phenotypic correlation between specific tension with good cocoon weight (-0.822), cocoon weight (-0.889) and cocoon shell weight (-0.854) was significant (P <0.05) but with the performance of each box, good cocoons number, number and weight of cocoons per liter, cocoon shell percentage and percentage of pupal mortality were not significant (P> 0.05). These results, which are reported for the first time in the country, showed that by increasing of the overall silkworm rearing performance (performance of each box) and cocoon weight, its strength decreased. In other word the tolerance of silk filament against the tensile force decreased by increasing cocoon weight traits.