Radiosensitivity and gamma-ray-induced vegetative variation in polyembryonic mango (Mangifera indica L.) cv. Olour for rootstock improvement

Abstract Gamma irradiation is widely used in mutation breeding to generate novel genetic variability; however, information on radiosensitivity and induced phenotypic variation in polyembryonic mango rootstock genotypes remains limited. The present study evaluated the effects of gamma irradiation on germination, survival, and vegetative growth traits of polyembryonic mango ( Mangifera indica L.) cv. ‘Olour’ to determine its radiosensitivity and identify an effective mutagenic dose range. Seeds were exposed to five gamma-ray doses (10, 15, 20, 25, and 30 Gy) alongside an untreated control and subsequently assessed for germination dynamics, survival, seedling growth, and morphological variation. Gamma irradiation caused a dose-dependent decline in germination and survival, with the LD₅₀ estimated at 19.54 Gy through Probit analysis and the GR 50 was estimated at 31.69 Gy based on fitted rergession model. Lower doses (10–15 Gy) stimulated growth traits, whereas higher doses (≥ 20 Gy) significantly reduced plant height, stem girth, internodal length, and leaf number. Increasing radiation doses also enhanced phenotypic variability, including alterations in leaf morphology and color of young and mature leaves. The observed reductions in seedling vigour and modification of architectural traits indicate a strong influence of gamma irradiation on vegetative development. The results demonstrate the effectiveness of gamma rays in generating phenotypic variability in polyembryonic mango and identify the 15–20 Gy range as a promising window for inducing desirable variations. These findings provide a reliable foundation for the future development and selection of improved mango rootstocks with altered growth architecture.