Standardization of embryo rescue technique for grape hybrids under sub-tropical conditions

Abstract

The development of new high yielding cultivars of good quality with large berry size is the main objective of seedless grape breeding programme. Seedless grapes suffer from stenospermocarpy so, technique of embryo rescue employing in-ovulo culture has been adopted in grape breeding in western world which not only produce superior seedless cultivars but also curtails 7-8 years from entire breeding cycle. With respect to mean ovule age (days after pollination) and ovule-embryo growth (2.13 mm2), culturing of ovules 24 days after pollination was found to be the best. The concentration of IAA (4 mg/l) + GA3 (0.5 mg/l) proved to be most effective for germination (13.84 %). Among various media used for culturing, ovules on MS medium (1/2 macro + 1/1 micro) registered highest germination (13.75%). Chilling treatment was proved to be one of the important factors for embryo maturation and 60 days of chilling treatment at 40C was found better than 45 days. With respect to the effect of different growth regulators on various rooting and shooting parameters IBA (1.0 mg/l) and NAA (1.5 mg/l) were found superior. While comparing different hardening strategies, glass jar with polypropylene cap (GPP) was found to be most effective as far as hardening success (66.67%) was concerned.