Frequency and Spectrum of Chlorophyll Mutations in Rice (Oryza sativa L.)

Background: This study was conducted to determine the lethal dose of the chemical mutagen ethyl-methane sulfonate (EMS) in a high-yielding rice variety, CO51. Chlorophyll mutation frequencies have been studied in the M2 generation. Methods: Lethal doses were determined through a pilot study, in which ten batches of rice seeds were treated with different doses of ethyl methane sulphonate (EMS) and kill curve analysis was carried out. Then, three batches of M1 population have been generated with the EMS doses of 0.5%, 0.6% and 0.7% respectively. Subsequently, in the next cropping, three batches of M2 population, consisting of 1030, 710 and 360 M2 families have been subjected to chlorophyll mutation have been studied. Result: The LD50 value resided between 0.5% and 0.6% EMS. A Gradual increase in the EMS dose increased the lethality in the rice in a linear fashion. The frequencies of the chlorophyll mutation were 3.59, 6.47 and 9.44 for the EMS doses of 0.5%, 0.6% and 0.7% respectively.