Enhancing Genetic Diversity and Blast Resistance in Rice (Oryza sativa L.) Through Ethyl Methane Sulfonate (EMS) Mutagenesis

ABSTRACT Plant diseases cause significant losses to food crop production with blast being one of the most destructive diseases affecting rice. Breeding for disease resistance is an effective approach for developing varieties that can withstand such diseases, ultimately contributing to stable yields in rice. Besides hybridization, chemical mutagenesis is a potential method of bringing desirable genetic alteration towards disease resistance in seed propagated crops like rice. Therefore, a study was conducted to generate variants employing ethyl methane sulfonate (EMS) mutagenesis, evaluate the resulting mutants for variability and identify genotypes resistant to rice blast disease following a completely randomized design (CRD). Seeds of BRRI dhan28 were mutagenized with LD50 (0.108 M) of EMS to develop 100 mutants. The mutants demonstrated notable variation in all traits assessed. The higher level of phenotypic and genotypic coefficient of variation was assessed together with high heritability as well as genetic advance in percent of mean for filled grains panicle −1 , tillers hill −1 , grain and straw yield hill −1 and harvest index. Plant height, panicle length, tillers hill −1 , branches panicle −1 and grains panicle −1 showed a statistically significant and positive correlation with grain yield. The cluster analysis grouped the mutants into seven main clusters, and the PCA demonstrated 42.96% of total variation for the first two components. Screening of the mutants against leaf blast disease exhibited variable responses from resistant to highly susceptible. A total of 9 mutants were found as resistant and 35 as moderately resistant against blast disease. Seed mutagenesis with EMS is an effective technique for generating variability towards blast resistance in susceptible rice varieties, and the identified resistant genotypes can serve as valuable resources for further research in improving blast resistance in rice.