Optimal Lethal Dose Determination for Gamma Rays and EMS Induced Mutagenesis in TMV7 and SVPR1 Sesame (Sesamum indicum L.) Varieties

In the present study two sesame varieties viz., TMV7 and SVPR1 were treated with varying doses of gamma rays (250, 300, 350, 400 and 450 Gy) and Ethyl Methane Sulphonate (EMS) of different concentrations viz.,0.20, 0.40 and 0.60%. The seed germination percentage was greatly affected by mutagenic treatment of gamma rays and EMS which showed a negative dose dependent relationship in both the varieties. The expected LD50 values were calculated through probit analysis. The LD50 values for TMV7 and SVPR1 were fixed at 416.86 Gy and 389.04 Gy for gamma rays and 0.490 % and 0.349% for EMS. The germination percentage of SVPR1 was greatly reduced (17.80 & 20.55 %) and the lethal dose to kill fifty per cent of mutated population was lower (6.68% & 28.78%) than that of TMV7 in both gamma ray and EMS treatment. EMS treatment exhibited significant reduction in seed germination (62.16 % & 66.67 %) than gamma irradiation (56.76 % & 54.55 %) in TMV7 and SVPR1 respectively. The study concluded that both the mutagens are effective to produce significant variations in sesame which can be further explored for mutation mapping.