RADIOSENSITIVITY RESPONSE TO ACUTE GAMMA IRRADIATION IN A MALAYSIAN RICE VARIETY, MR284
Rice is an important staple food and provides 20% of the world’s dietary energy supply. Presently, mutation-based breeding is extensively used in rice to induce genetic variation by improving yield and agronomic traits as well as increasing tolerance to pest and diseases. Our aim in this study is to determine the radiosensitivity of a Malaysian rice (Oryza sativa L.) variety, MR284 to acute gamma irradiation. Dry MR284 seeds were exposed to acute gamma irradiation (high dose rate radiation) using Biobeam GM8000 with Caesium-137 as a source at doses of 0, 100, 200, 300, 400, 600, 800 and 1000 Gy at Malaysian Nuclear Agency. Effects of irradiation were measured in terms of shoot and root length. Study showed that irradiated seedlings demonstrated a reduction in plant height with increasing doses of gamma irradiation. Based on the survival curve, the 50% shoot length (SD50) for MR284 was 390.74 Gy. At doses above 800 Gy, physiological damage on the seedling in terms of plant height and root length became more severe and none of the seedlings were survived. Therefore, the study concludes that the SD50 for MR284 rice was in the range of 300 to 400 Gy and provides evidence that MR284 rice genotype displayed variable response towards gamma radiations after germination.