Radiosensitivity of the excised rice embryo.

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…