A case study on three cultivars and optimization of LD50 dose of gamma irradiation for inducing variability in pomegranate for horticultural traits and bacterial blight resistance

Effective induced mutation breeding entails determining the ideal radiation dosage by examining how it influences the growth attributes of the crop. For evaluating the impact of different doses of gamma radiation on pomegranate (Punica granatum), three cultivars viz., Kandhari Kabuli, Bhagwa and Daru were treated with physical mutagen (gamma rays) at doses of 0, 6, 9, 12, 15, 18, 21, 24 kR to induce variability. The observations were recorded at different time intervals after sowing in the polyhouse and after transplanting in field conditions (20, 30 and 40 days after sowing and 70 days after transplanting, subsequently). The germination percentage, survival percentage and LD50 doses were calculated for all three cultivars. Mutant seedlings from different concentrations of gamma rays were evaluated for chlorophyll content of leaves and molecular characteristics. The LD50 doses for CVS. Kandhari Kabuli, Bhagwa and Daru were 15.26 kR, 15.08 kR and 13.74 kR, respectively. Statistical analysis revealed significant dose-dependent reductions in germination and survival rates (p < 0.05), with LD₅₀ values determined to be 15.26 kR for Kandhari Kabuli, 15.08 kR for Bhagwa and 13.74 kR for Daru. These results demonstrate scientifically important variability among cultivars in their sensitivity to gamma radiation, providing critical reference points for optimizing mutagenic doses in pomegranate breeding programs.