Effect of ethyl methanesulfonate mediated mutation for enhancing morpho-physio-biochemical and yield contributing traits of fragrant rice

BACKGROUND: Chemical mutagenesis has been successfully used for increasing genetic diversity in crop plants. More than 800 novel mutant types of rice (Oryza sativa L.) have been developed through the successful application of numerous mutagenic agents. Among a wide variety of chemical mutagens, ethyl-methane-sulfonate (EMS) is the alkylating agent that is most commonly employed in crop plants because it frequently induces nucleotide substitutions as detected in numerous genomes. METHODS: In this study, seeds of the widely consumed Basmati rice variety (Super Basmati, Oryza sativa L.) were treated with EMS at concentrations of 0.25%, 0.50%, 0.75%, 1.0%, and 1.25% to broaden its narrow genetic base. RESULTS: Sensitivity to a chemical mutagen such as ethyl methanesulfonate (EMS) was determined in the M1 generation. Results in M1 generation revealed that as the levels of applied EMS increased, there was a significant reduction in the germination percent, root length, shoot length, plant height, productive tillers, panicle length, sterile spikelet, total spikelet, and fertility percent as compared to the control under field conditions. All the aforementioned parameters decreased but there was an increase in EMS mutagens in an approximately linear fashion. Furthermore, there was no germination at 1.25% of EMS treatment for seed germination. A 50% germination was recorded between 0.50% and 0.75% EMS treatments. After germination, the subsequent parameters, viz. root length and shoot length had LD(50) between 05.0% and 0.75% EMS dose levels. Significant variation was noticed in the photosynthetic and water related attributes of fragrant rice. The linear increase in the enzymatic attributes was noticed by the EMS mediated treatments. After the establishment of the plants in the M1 generation in the field, it was observed that LD(50) for fertility percentage was at EMS 1.0% level, for the rice variety. CONCLUSION: Hence, it is concluded that for creating genetic variability in the rice variety (Super Basmati), EMS doses from 0.5% to 0.75% are the most efficient, and effective.