Optimizing the gamma radiation dose for growth performance of Hassawi rice ( Oryza sativa L.)

Gamma irradiation is a crucial step for enhancing genetic variability and improving crop traits when conducting mutation breeding. Thus, this study aimed to identify the optimum irradiation doses that enhance growth while avoiding damage during the early seedling growth phase of Hassawi rice (Oryza sativa L.). Seeds were exposed to six gamma irradiation doses (0, 100, 200, 300, 400, and 500 Gy) using a Cobalt-60 source and grown under controlled laboratory conditions. Seedling growth traits, including shoot length, root length, and total seedling length, were measured at two intervals one week apart. Growth responses showed a clear dose-dependent pattern with significant differences among the treatments (p < 0.05). Low-to-moderate doses (100–300 Gy) stimulated or maintained seedling growth, with notable increases in shoot and total seedling lengths at specific stages, indicating hormetic effects. In contrast, higher doses (≥400 Gy) consistently reduced shoot, root, and total seedling length, markedly impairing seedling vigor. This study highlights the value of gamma irradiation as a tool for crop improvement when applied at low doses (100–300 Gy) and recommends further research on yield-related traits to enhance practical agricultural applications.