EFFECTS OF CHRONIC GAMMA IRRADIATION ON THREE RICE VARIETIES
Rice is the most important staple food for a large part of the world’s human population, especially in tropical Latin America, the West Indies, East, South and Southeast Asia. Mutation-based breeding is to develop and improve plant varieties by modifying one or two major traits to increase their productivity or quality in a relatively short time than conventional breeding. This is now widely used in agriculture to get the success rapidly. The present study inspects the effect of chronic gamma irradiation on rice (Binadhan-8, NMR-152 and Pongsuseribu-2) varieties. Rice seedlings at the age of 14 days were exposed to chronic gamma irradiation (low dose rate radiation) in Gamma Green House (GGH) at Malaysian Nuclear Agency for 60 days. The treated seedlings were designated in three replicates. The accumulated doses received by the rice plants were from 29 to 639 Gy for 60 days. Control plants were grown outside the gamma green house. The plant heights were recorded every week after planting in GGH. Effects of radiation were measured in terms of plant height, number of tiller and number of filled grain produced. At cumulative doses of 67 and 162 Gy (0.07and 0.17 Gy/hr, respectively), the rice seedlings showed the highest plant height with maximum tillering and highest number of filled grain. Those rates are stimulating to the growth and development of the plants. This study helps explicate the biological effects of low-dose gamma irradiation in rice plants at various exposure periods.