Sensitivity of rice varieties to gamma irradiation

Six promising rice varieties viz., CO 43, CO 47, CO 48, CO 49, ADT 43 and Improved White Ponni were treated with gamma irradiation with doses of 100Gy, 200Gy, 250Gy, 300Gy and 350Gy of gamma rays in order to study effect of gamma irradiation in seed germination of rice varieties and study the root and shoot length variation. Treated seeds were sown separately in germination paper and nursery with the two replications. The germination percentage was decreased after gamma irradiation. But the decrease was neither proportional to the increase in dosage nor definite pattern was found in all the six rice varieties. At the dose of 350Gy all the six varieties exhibited the low germination percentage especially in the variety ADT 43 is 33%. The gamma ray dose of 300Gy was causing 42-51% seedling height reductions in CO 43, CO 47, CO 48, CO 49 and ADT43. The seedling height was decreased in decreasing manner with the increase of irradiation dose in the varieties such as CO 47 and improved white ponni. The root development in seedlings was inhibited higher in the dose of 300Gy in all the six varieties. At higher dose of 350Gy root length is very much affected in the varieties viz., CO 43 with 76% reduction and 70% reduction in improved white ponni. Plant height and seed fertility percentage were decreased with increase of gamma radiation dose in linear fashion. Seed fertility decreased with increase of radiation dose was observed in CO 47, ADT 43 and improved white ponni. In ADT 43 seed fertility was reduced approximately 69% at gamma ray dose of 350Gy.