Response of excised embryos of rice (Oryza sativa L.) to X-rays.

The response of rice (Oryza sativa L.) embryos to X-rays (M1 to M3) was studied. By means of irradiating excised embryos, both chlorophyll and macromutation were successfully induced in three genotypes of rice. However, differential responses in terms of mutation frequency, mutation spectrum and optimal levels of X-rays required for induction of mutation (chlorophyll as well as morphological) were found to exist between cultivars. In 'Satika' and 'Ashkhata', LD50 values and maximum induced seed sterility are concomitant to optimum level of radiation required for triggering chlorophyll mutation. However, optimum dose for induction of macromutation in 'Satika' and 'Kerangserang' is independent of either LD50 and/or induced seed sterility.Chances of obtaining both dominant and locus specific recessive mutations in the immediate X-ray treated generation (M1) are large. This indicates the very high degree of effectiveness of the excised embryo irradiation technique with rice.