Radiation induced mutagen sensitivity and chlorophyll mutation frequency on sesame seeds

Aim: Effect of gamma irradiation on genomic disorder in sesame are scanty. The present study was undertaken to evaluate the mutagenic effects of gamma rays on different parameters in two popular cultivars of sesame, Roma and Tilottama. Methodology: Seeds of these two cultivars were irradiated with five doses of gamma rays: (250, 300, 350, 400, and 450 Gy) at BARC, Trombay and were sown (along with the un-irradiated control) during March 2015 in a split plot design with 3 replications keeping row to row and plant to plant distance at 30 cm and 10 cm, respectively to determine mutagen sensitivity with regard to pollen fertility (%), germination (%) and seedling height (cm), root-shoot length (cm), plant survival (%) at maturity in M-1 generation. To study mutability, four to five capsules from each M-1 plants in all the treatments were collected separately to give rise the M-2 generation. Individual plant progeny rows were sown in M-2 during March 2016. ID50 was determined by probit analysis for germination, shoot-root length and plant survival. Since the dose requirement for pollen fertility is very high, ID30 was calculated instead of ID50 value. Results: It was observed that with increasing doses of gamma rays, the response of all characters decreased significantly and followed a linear relationship in both varieties. The root system was more profound to gamma rays than the shoot. Chlorophyll mutations showed independent response to different doses of gamma rays as they occurred in random. The mutability of genotype Roma induced with different doses of gamma rays was higher than that of Tilottama. Interpretation: Due to saturation in the mutational actions, response of characters decreased with increase in gamma ray doses but magnitudes of effect differed between genotypes. The cultivar Tilottama was found to be more sensitive than Roma.