Effect of varied photoperiod regimes on the commercial characters of silkworm, Bombyx mori L.

The bivoltine Silkworm race SK7 (Berhampur) was selected as an experimental material. The disease-free laying's (DFL's) were obtained from the Silkworm Germplasm Bank of College of Temperate Sericulture, Mirgund (SKUAST-K). The laying's were incubated under different photoperiod regimes till hatching with a control group keeping Temperature (25±1°C) and Relative Humidity (80±5 %) constant. Rearing of the treated batches was conducted by maintaining three replications per treatment adapting standard package of practices. The study revealed significant increase in all the larval, cocoon and egg parameters. Among the six treatments evaluated T₆ (24L: 00D) revealed significantly best results followed by T₅ (20L: 04D) which also showed better results in all the parameters. Improvement in most of the parameters was observed with respect to the treatments exposed to longer light durations. The significantly highest values obtained for the parameters include hatching percentage (95.6%), larval weight (40.60g), single cocoon weight (1.930g), ERR by number (9892/10,000 larvae), and by weight (19.093 kg), pupal weight (1.533g), sex ratio (75.67 females and 24.33 males) and fecundity (732.67) recorded in T₆ (24L:00D). T₀ (16L: 08D) recorded significantly maximum survival percentage and pupation rate of 95.67% and 94% respectively. The significantly highest moth emergence percentage (99.57%) was recorded in T₁ (00L: 24D). However, there was no impact of varied photoperiod regimes on the morphology of the moths.