Comparative analysis of gamma rays and electron beam in altering rice (Oryza sativa L.) grain size

Main objective of this study was to alter the grain size of drought tolerant Anna (R) 4 rice variety, because it fetches less market due to its long slender grain type. Hence to reduce the grain size, the seeds of Anna (R) 4rice were irradiated with physical mutagens namely gamma rays and electron beam. The small grain size mutants from 200, 250, 300 and 350 Gy were advanced to M2 and further generations. The maximum kernel length reduction obtained was 6.04 and 5.71 mm in M2 generation of gamma rays and electron beam respectively. On selection of small grain mutants over generations, the more number of mutants was realisedfrom electron beam in M4 generation especially at 300 Gy, in terms of reduced kernel length, kernel width and grain weight. This offers chance to selecting early maturing and high grain yield per plant over wild type. These findings indicated that mutation approach by electron beam offers high chance of getting small grain size mutants as well as grain yield improvement than gamma rays.