부산대학교 도서관

Rice (Oryza sativa L.) plays a pivotal role in global food security, necessitating continuous efforts to enhance yield potential and grain quality. Mutation breeding, employing physical (electron beam) and chemical (ethyl methane sulphonate, EMS) mutagens, offers a promising avenue for creating genetic variability. This study assessed the sensitivity of rice variety ASD 16 and landrace Norungan to varying doses of electron beam (100 Gy to 500 Gy) and EMS (30 mM to 70 mM). The genotypes exhibited dose-dependent responses in germination, seedling survival, shoot and root length, seedling height, pollen fertility and spikelet fertility. The LD50 values for electron beam under in vivo and in vitro conditions were 314.24 Gy and 348.21 Gy respectively for ASD 16 and 445.07 Gy and 461.88 Gy for Norungan whereas for EMS, the LD50 values for ASD 16 were 49.17 mM and 55.37 mM; 53.53 mM and 65.12 mM for Norungan under in vivo and in vitro conditions based on probit analysis. ASD 16 showed a GR50 value of 309.02 Gy for the electron beam and 51.60 mM for EMS while Norungan exhibited a GR50 value of 538.79 Gy for electron beam and 98.71 mM for EMS. The variety, ASD 16 demonstrated higher sensitivity, proved by greater growth reduction percentages and lower lethal dose 50 (LD50) values compared to landrace Norungan. Electron beam treatments induce significant reductions in various growth traits, underlining the potential deleterious effects at higher doses. EMS, as a chemical mutagen, also impacted germination and growth characteristics. Both mutagens affected pollen and spikelet fertility with notable influence on yield contributing traits. This finding emphasizes the significance of precise dosage selection in mutation breeding to induce desirable traits and maintaining complete plant viability and productivity. Understanding genotype-specific responses is crucial for successful mutation breeding programmes. Overall, this study offers valuable insights into the application of electron beam and EMS mutagenesis in rice, contributing to the optimization of mutagenic protocols for crop improvement. [ABSTRACT FROM AUTHOR]