Exploring differential radiosensitivity in soybean genotypes exposed to gamma rays and determining optimal doses for induced mutagenesis

Ionizing radiation serves as a powerful tool in mutation breeding, enabling plant breeders to induce genetic variability and develop novel crop varieties with desirable traits. This study investigated the effects of gamma radiation, a potent form of ionizing radiation, on four soybean cultivars. The cultivars were exposed to gamma ray doses ranging from 0 Gy (control) to 600 Gy. The objective was to assess the impact of varying radiation doses on soybean genotypes and determine the optimal dose for induced mutagenesis based on lethal dose (LD50) and growth reduction (GR50) studies. Results revealed a negative correlation between increasing gamma doses and seedling growth across all genotypes. This was evident from reductions in shoot length, survival percentage, plant height, germination percentage, and dry weight. Interestingly, root length exhibited radiation hormesis, showing stimulation at low doses. Among seedling traits, shoot length and survival percentage were identified as the most sensitive to gamma radiation. The study found genotype-specific differences in radiosensitivity, with LD50 values ranging from 313 to 345 Gy and GR50 values from 295 to 335 Gy across the tested genotypes. Notably, JS 20–98 emerged as the most sensitive genotype, while MACS 13 was the most tolerant. These findings underscore the necessity of standardizing optimal radiation doses for each genotype prior to large-scale mutagenesis programs to ensure the efficient generation of desired mutants. This research highlights the intricate relationship between radiation dose and genotype-specific responses, offering critical insights for developing effective mutation breeding strategies. The study provides a robust foundation for utilizing gamma irradiation in soybean improvement programs.