Determination of Lethal Radiation and Ethyl Methane Sulphonate Doses for Mutagenesis in Green Gram (Vigna radiata (L.) Wilczek)

Green gram (Vigna radiata L.) is a nutritionally rich and versatile crop widely used for food and feed. However, its genetic improvement through conventional breeding is constrained by self-pollinating flowers and limited genetic diversity, making traditional methods inefficient for yield enhancement. Induced mutagenesis offers a viable alternative to create novel genetic variability. This study aimed to establish the mean lethal dose (LD50) of ethyl methane sulphonate (EMS) and gamma irradiation in three green gram varieties (Shwe Toe-009, MAS-1, and Yezin-9). Nine EMS concentrations (0.00% [control], 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35 % and 0.40%) and seven gamma radiation doses (0 Gy [control], 200 Gy, 400 Gy, 600 Gy, 800 Gy, 1000 Gy and 1200 Gy) were applied. Results showed a progressive decline in germination and survival percentages with increasing mutagen doses. Probit analysis revealed that EMS-treated samples exhibited similar LD50 values across all varieties, reflecting its uniform biochemical mode of action (alkylation of DNA bases). Gamma-irradiated samples displayed genotype-dependent LD50 values, attributable to varietal differences in seed morphology, antioxidant capacity, and DNA repair efficiency against radiation-induced chromosomal damage. The predicted LD50 ranges were 400–650 Gy for gamma rays and 0.4% for EMS, providing optimal doses for balancing mutation induction with plant survival. These findings enable large-scale mutagenesis programs to generate diverse mutant populations for green gram improvement.