Integration of Mutation and Conventional Breeding Approaches to Develop New Superior Drought-tolerant Plants in Rice (Oryza sativa)

Present study was carried out to investigate the possibility of developing new superior drought-tolerant plants in rice by mutation breeding. Major regions of rice cultivation especially in Iran and Asia are affected continuously by drought stress especially at the end of flowering stage. To identify resistant plants, water stress was imposed on mutant rice plants in the field in flowering stage. In total, 23 tolerant mutant plants under drought stress were obtained after three generations of selection on mutants. Only 17 M4 lines had high yield and were selected as resistant. Also, morphological parameter evaluations of 29 mutant lines grown under natural conditions indicated that 14 lines were early flowering by 7 days or more and the height of 8 mutant lines had been decreased by 30 cm or more than control. Also, 11 lines had yields of more than 5000 Kg/ hectare. On obtained results of phenotypic evaluations of mutant plants under drought stress and normal conditions, 11 lines were selected for descent test and yield experiments in several regions and years.