Characterization and breeding value of morphological mutants derived from electron beam and gamma rays in rice (Oryza sativa L.)

Asia dominates global rice production, accounting for around 90 % of the world's total. Rice is considered as one of the model crops for physical irradiation in mutation studies. Among the physical sources of gamma rays, mutagenic studies have been conducted over several years, but nowadays focus on the emerging physical irradiation source of electron beam due to its action towards biomaterial is effective than gamma rays. The seeds of rice variety Anna (R) 4 were subjected to gamma rays and electron beam irradiation with four different doses (200, 250, 300 and 350 Gy). The primary panicles were collected from each plant in M1 generation, forwarded to M2 and M3 generation as panicles-to-progeny row progenies. The identified mutants from irradiated populations were characterised using DUS test guidelines, followed by prepotency assessment for selected mutants. The maximum frequency was recorded in the electron beam (0.057) than in the gamma rays (0.034) irradiated population. Among the irradiation doses, 300 Gy of electron beam showed a higher frequency (0.099). The morphological mutants related to grain mutants, high tillering, early flowering mutants and flower organisation mutants were recorded maximum in the electron beam than in the conventionally used gamma rays. In the M3 generation, the mutants of grassy and extreme dwarf, extra glume type and grain mutant showed true to type. The present study revealed that the electron beam showed a higher frequency of morphological mutants than the gamma rays.