Marii, LilianaAndronic, LarisaSahanovschih MarionelaUrsachi Olga2025-09-012025MARII, Liliana; Larisa ANDRONIC; Marionela SAHANOVSCHIH and Olga URSACHI. Variation in tomato genotypes response to X-ray irradiation and estimation of the effective doses. In: International Congress of Geneticists and Breeders of the Republic of Moldova: Materials Proceedings, 12-th edition, Chisinau, September 17-18, 2025. Chisinau: Editura USM, 2025, pp. 271-279. ISBN 978-9975-62-897-6. Disponibil: https://doi.org/10.53040/cga12.39978-9975-62-897-6https://msuir.usm.md/handle/123456789/18564https://doi.org/10.53040/cga12.39The study investigates the response of 15 tomato genotypes (cultivated and wild forms) to X-ray irradiation, aiming to determine effective mutagenic doses that result in a 50% reduction in key quantitative parameters: germination rate, radicle length, hypocotyl height, and seedling height. Seeds were exposed to 10 irradiation doses (ranging from 100 to 530 Gy), and the effects were assessed in comparison to a non-irradiated control. Linear, nonlinear, and polynomial regression models were applied, along with dose–response curve analysis, to estimate the effective inhibitory doses (ID₅₀/ID₃₀) for the efficient use of induced mutagenesis in the M₀ and subsequent generations. The results reveal considerable variability among genotypes, including stimulatory (hormetic) effects at lower doses. These findings are essential for optimizing mutagenesis protocols in tomato breeding programs.enmutagenesistomatoregressionvariabilityX-raysArticle