| Popis: |
Classical cytoplasmic male sterility (PET-1) discovered by Leclercq and a few restorer lines are being utilized for commercial hybrid seed production in sunflowers over the world since 1972. The utilisation of a single source of male sterility results in a high level of vulnerability to biotic and abiotic stresses. The goal of this study was to identify new fertility restorers for two different cytoplasmic male sterile sources, i.e., PET-1 (COSF-6A, COSF-7A, CMS-38A, ARM- 248A) and CMS PEF (FMS-852A). Five CMS lines were crossed with newly developed drought tolerant 10 inbred lines in Line x Tester fashion and an evaluation of test cross progenies was conducted. All the inbreds were categorized into complete, partial restorers and maintainers through cytological observation. Six inbreds, viz., RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP-233 behaved as restorers for all the CMS lines and restored fertility, while RGP-222 and 298R inbreds maintained sterility. The CMS line, FMS-852A was maintained by four inbreds indicating the involvement of different gene(s), while six inbreds, RGP-157, RGP-184, RGP-190, RGP-223, RGP-225 and RGP- 233 were restored its fertility. None of the inbreds behaved as partial restorers for any of the CMS lines. The fertility restoration ranged from 91.4 to 97.4 per cent in different cross combinations. In the present study, pollen fertility of up to 80 per cent was observed for the PET-1 source. However, only 60 per cent of the pollen fertility was observed for CMS fallax. From the study, it was evident that among the two CMS sources, restorers for PET-1 and PEF were available. Efforts should be made to utilize CMS PEF for the production of more productive sunflower hybrids resistant to biotic and abiotic stresses. |
