STUDIES ON COMBINING ABILITY AND HETEROSIS IN SOME BIVOLTINE BREEDS OF SILKWORM, Bombyx mori L.
| dc.contributor.advisor | GOVINDAN, R. | |
| dc.contributor.author | SHASHIKANT RAYAR, G. | |
| dc.date.accessioned | 2017-03-01T08:13:18Z | |
| dc.date.available | 2017-03-01T08:13:18Z | |
| dc.date.issued | 2009-08-18 | |
| dc.description.abstract | Investigations were carried out to study the combining ability and heterosis in some bivoltine silkworm breeds through Line x Tester analysis. Seventeen bivoltine pure breeds were reared twice and evaluated for fifteen quantitative traits so as to finally select the parents. Based on the multiple traits evaluation index values, seven oval cocoon breeds viz., SH-6, KPGA, CC-1, CSR-2, CSR-27, KSO-1 and APS-5 were selected as lines and crossed with each of the selected dumbbell cocoon breeds viz., NB4D2, CSR-4, CSR-26, APS-8 and NP-2. All the 35 single cross hybrids and their parents were evaluated across three seasons (rainy, winter and summer) for fourteen quantitative traits. The mean performance among the hybrids was significantly superior in KSO-1 x CSR-4 for eleven traits, followed by SH-6 x CSR-4, KSO-1 x NB4D2, KSO-1 x NP-2, APS-5 x NP-2, APS-5 x CSR-26 and APS-5 x APS-8 for ten traits each. The variance due to specific combining ability (SCA) was higher than that of the general combining ability (GCA) for all the traits, indicating the predominance of non-additive gene action in controlling the traits. The parents, KSO-1, APS-5, CSR-2 and CSR-27 as lines and NP-2 and CSR-4 as testers were the best general combiners for most of the traits. KSO-1 x CSR-4 ranked top by recording the highest specific combining ability for eleven traits. While, KPGA x NB4D2 and CSR-2 x CSR-4, KPGA x APS-8 and APS-5 x CSR-26 hybrids yielded high SCA effects for eight and seven traits each, respectively. Higher heterotic value for majority of the traits was exhibited by KSO-1 x CSR-4, APS-5 x CSR-26, CSR-27 x CSR-4, APS-5 x APS-8 and CSR-27 x CSR-26 hybrids. The multiple traits index value was highest in KSO-1 x CSR-4 and it ranked top among hybrids. Considering the rearing performance, specific combining ability, heterosis and evaluation index, KSO-1 x CSR-4 was adjudged as the potential hybrid for commercial exploitation. Genetic divergence among the seventeen bivoltine breeds indicated a distant diversity as they formed six clusters. The large-scale evaluation of KSO-1 x CSR-4 hybrid at three different locations revealed its better performance over CSR-2 x CSR-4 and KPGA x NB4D2 hybrids. | en_US |
| dc.identifier.other | Th-9452 | |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810003346 | |
| dc.language.iso | en | en_US |
| dc.pages | 297 | en_US |
| dc.publisher | University of Agricultural Sciences GKVK, Bangalore | en_US |
| dc.sub | Sericulture | en_US |
| dc.subject | null | en_US |
| dc.theme | SILKWORM | en_US |
| dc.these.type | Ph.D | en_US |
| dc.title | STUDIES ON COMBINING ABILITY AND HETEROSIS IN SOME BIVOLTINE BREEDS OF SILKWORM, Bombyx mori L. | en_US |
| dc.type | Thesis | en_US |