Induced Viable Mutation Studies in M₂ Generations of Rathu Heenati and PTB33

Rice is one of the most important food crops in the world, which has been exposed extensively to mutagenic treatments for induction of variability. It has contributed greatly in creating broad genetic variability and a large number of varieties has been released directly or through cross breeding. The field experiment was conducted during Rabi 2010–2011 to study the viable mutation exhibiting variability in their morphology suchas chlorophyll deficiency, plant height, and awn development characters mutants were identified and isolated from two genotypes of rice from M₂ generation, after treatment with gamma rays at six different doses. Aberrant possessing altered plant height, duration, grain type, plant type and presence of awns in grains were noticed. The frequency of viable mutantswas independent to genotype and mutagen. In general the frequency of viable mutants was found to be maximum in PTB33 (1.8 per cent) where as in Rathu Heenati 1.50 per cent.