In vitro radio-sensitivity (Gamma irradiation) of some juice and wine making grape genotypes

Irradiation sensitivity of four juice and wine genotypes i.e., Pusa Navrang, Pearl of Csaba, Hybrid 76-1 and Julesky Muscat was ascertained. Well proliferated cultures these genotypes were raised on standardized proliferation cum rooting medium (MS basal medium + 2.0 mg/l IBA + 250 mg/l activated charcoal) were subjected to Gamma irradiation treatments (0, 5, 15, 20, and 25 Gy). The cultures after irradiation were sub-cultured following in vitro repetitive micro-cutting technique on the same medium upto five cycles (vM₅). Thereafter, the in vitro rooted plantlets were hardened and later transferred in pots in glasshouse for survival and morphological analysis. Results showed that the highest mean explant survival was noted in the control (83.78%) over other irradiation dosages except 5 Gy dose (80.95%), which were at par. The gamma irradiation dose of 10 Gy gave the mean survival of 46.66%, shoot sprouting (56.85%) and in vitro shoot abnormalities (50.59%), which were significantly different from the other irradiation dosages. The 10 Gy irradiation dose was recorded as a lethal dose 50 (LD₅₀) for all genotypes. However, as the irradiation dose was increased further, the explant survival percentage, shoot sprouting and in vitro shoot and root abnormalities significantly enhanced. The highest shoot sprouting was noted in Pusa Navrang (57.59%) followed by Pearl of Csaba (55.59%). Surviving mutants showed altered physiological traits with increasing doses of Gamma irradiation.