Effects of gamma-ray irradiation on agronomic traits and determination of the optimal mutagenic dose (LD

This study aimed to determine the effects of gamma irradiation on the agronomic characteristics of the local rice cultivar Mayas and to identify the optimal radiation dose that may produce superior mutant lines. Mayas rice seeds were irradiated with gamma rays at doses of 0, 50, 100, 150, 200, 250, and 300 Gy. Gamma irradiation significantly affected seed germination and mortality rates. The highest germination percentage was observed at a dose of 50 Gy (88%), whereas higher doses (250–300 Gy) resulted in reduced germination and increased seed mortality up to 50%. The LD50 value was estimated at approximately 295 Gy, indicating that this dose caused 50% seed mortality. Plant height decreased with increasing radiation doses, with the lowest average height observed at 100 Gy (73 cm) compared to the control (125 cm). Conversely, the number of tillers and productive tillers increased under low to moderate radiation doses. The 50 Gy treatment produced the highest number of tillers per clump (50 tillers) compared to the control (13 tillers) and the greatest number of productive tillers (25 tillers) compared to the control (4 tillers), demonstrating the stimulatory effect of gamma irradiation on vegetative growth and yield potential.