Radiosensitivlty of the Wild and Cultivated Urd and Mung Beans

Seeds of Vigna sublobata, V. radiata cv. PS 16, and V. mungo cv. T 9 were used for the induction of mutations with EMS and gamma rays. Four doses each of these mutagens (EMS: 0.1, 0.2, 0.3 and 0.4%; gamma rays: 10, 20, 30 and 40 kR; EMS + gamma rays: 0.1% + 10 kR, 0.2% + 20 kR, 0.3% + 30 kR, and 0.4% + 40 kR) were employed. Mutagenesis lowered the dehydrogenase activity in M₁ and M₂ plants of all three species. Dose-dependent decrease was observed in seedling emergence, seedling height, survival, and pollen fertility in M₁ and M₂ plants. The spectrum of chlorophyll mutations was narrow; the spectrum and frequencies of chlorophyll mutations increased with dose of each mutagenic treatment. The observations suggested that i) V. subtobata is more radioresistant as compared to V. radiata and V. mungo, ii) V. radiata is more radiosensitive than V. mungo, and iii) V. sublobata is more closely related to V. mungo than to V. radiata.