Determination of optimal gamma-ray irradiation doses and recovery of putative low-vigor lines in Myrobalan plum (Prunus cerasifera Ehrh.)

The development of dwarfing rootstocks is a major objective in stone fruit breeding because reduced tree vigor improves orchard management and enables high-density planting systems. However, genetic improvement of perennial rootstocks is constrained by long breeding cycles and limited genetic variability. This study evaluated the potential of gamma-ray-induced mutagenesis to generate putative low-vigor lines of Myrobalan plum ( Prunus cerasifera Ehrh. ), a widely used rootstock for stone fruit production. In vitro-grown shoot tips were exposed to gamma irradiation (10–80 Gy), and responses were assessed through survival, vegetative growth, rooting performance, and preliminary field evaluation. Gamma irradiation induced a clear dose-dependent response. The 10 Gy treatment enhanced shoot-let proliferation, elongation, and rooting, consistent with a low-dose hormetic-like response, whereas higher doses progressively reduced growth and survival. Regression analysis estimated LD 25 , LD 50 , and LD 75 values of 28.38, 45.93, and 63.47 Gy, respectively, while GR 50 values ranged from 36.72 to 44.10 Gy. Principal component analysis showed strong coordination among growth-related traits, with the first component explaining 98.32% of total variation. Field assessment in a single measurement season revealed significant reductions in plant height and internode length, with the 60 Gy treatment showing the lowest measured values; however, these reductions coincided with marked growth inhibition at high dose. The results identify putative low-vigor lines worthy of further evaluation, but they do not establish genetic stability or confirm dwarfing effects on grafted scions.