Induced Mutagenesis for Creating Variability in Thailand’s Upland Rice (Cv. Dawk Pa-yawm and Dawk Kha 50) using Ethyl Methane Sulphonate (EMS)

To enhance the genetic variability and to create new and diverse characters to a natural population, researchers sometimes opt for mutation breeding. This research has been done to investigate the effective doses of EMS and to observe the phenotypic variability of the two upland rice genotypes Dawk Pa-yawm (white rice) and Dawk Kha 50 (red rice), in Thailand. Seeds of the potential genotypes has been treated with varying EMS concentrations. With the increase in concentration, there was a continuous decrease in germination, shoot and root lengths respectively. Data have been subjected to regression analysis and effective doses of EMS were recorded for both genotypes. The effective value calculated for shoot and root length in Dawk Pa-yawm was 1.34% and 1.33% and in Dawk Kha 50, 1.23% and 1.86% respectively based on the reduction of the above mentioned parameters after the EMS treatment. Furthermore, the EMS response in M1 generation was also observed in the field condition by various quantitative measurements. The traits, especially plant height, panicle length, number of filled grains, number of grains per panicle, 1000 grain weight and yield per plant showed a clear fall off when compared to control while the panicle length in both mutants were higher than that of control. Several mutants also revealed some notable phenotypic variations in the roots, seeds, panicles and leaf morphology. Phenotypic observations determined that the Dawk Kha 50 has more potential of variability than Dawk Pa-yawm towards EMS. Later selection in the advance generations might be useful to isolate agronomically useful mutants for the future use in upland rice breeding programme.