Evolution of new productivity bivoltine hybrids CSR2 x CSR4 and CSR2 x CSR5
2000
Datta, R.K. (Central Sericulture Research and Training Institute, Mysore (Inde)) | Basavaraja, H.K. | Mal Reddy, N. | Nirmal Kumar, S. | Ahsan, M.M. | Suresh Kumar, N. | Ramesh Babu, M.
With an objective of evolving robust bivoltine breeds/hybrids of silkworm Bombyx mori L., for tropical conditions, breeding programme was undertaken by utilising two Japanese hybrids namely Shunrei x Shogetsu, BN18 x BCS25 and an Indian popular bivoltine breed, NB4D2. The breed CSR2 spinning white oval and CSR5 spinning white dumbbell cocoons were isolated from Japanese commercial hybrid Shunrei x Shogetsu through repeated inbreeding coupled with selection, while CSR4 spinning white dumbbell cocoons was evolved from Japanese hybrid BN18 x BCS25 crossed to NB4D2. After fixation, these breeds along with other newly evolved breeds were subjected for hybrid study using large number of hybrid combinations in the laboratory and evaluated by Evaluation Index method. The hybrids viz., CSR2 x CSR4 and CSR2 x CSR5 were found promising. The hybrids CSR2 x CSR4 and CSR2 x CSR5 recorded survival of 96.5 and 97.1%, shell weight of 46.5 and 48.7 cg, shell ratio of 23.5 and 24.1%, raw silk percentage of 20.0 and 20.5%, filament length of 1147 and 1278 m and renditta of 5.0 and 4.9 kg, respectively, whereas the control hybrid (KA x NB4D2) has recorded survival of 93.8%, shell weight of 40.7 cg, shell ratio of 20.5%, raw silk percentage of 17.2%, filament length of 1035 m and renditta of 5.8. The new hybrids showed neatness of above 94.4 p as against 93.3 p in control hybrid. These hybrids were authorised for commercial exploitation during 1997 by Central Silk Board based on the results obtained from 10 test centres located at various regions
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