Radiosensitivity of the Excised Rice Embryo

Abstract

Excised embryos (mature and immature) of five varieties of rice (Oryza sativa L.) were exposed to different levels of X-rays to assess the relative radiosensitivity response in vitro. The results indicated that: 1) germination was not affected in any of the varieties irrespective of X-ray doses and ages of the embryo, 2) the injurious effect of X-rays on germinating seedlings became visible from sixth day and seedling lethality could be noticed only from the seventh day onwards, 3) the LD₅₀ value differed in different varieties, 4) early duration varieties were more sensitive to radiation than late, so also varieties with smaller embryos over those with larger ones, 5) the ‘day-neutral’ varieties were more resistant than ‘short-day’ types, 6) immature embryos were more sensitive to X-rays than matured ones, 7) a differential response to X-irradiation was noticed between varieties in vitro.