Evaluation of gamma-irradiated Pisum sativum germplasm for agronomic traits and tolerance to Didymella pinodes

Ascochyta blight, caused by a complex of pathogenic fungi including Didymella pinodes, Ascochyta pisi, and Phoma pinodella, is a major disease of field pea (Pisum sativum), causing severe losses through lesions on leaves, stems, and pods. Mutation breeding using gamma irradiation is a non-GMO strategy to induce genetic variation and accelerate the development of improved genotypes. In this study, the M2 generation of the forage pea cultivar Dodoni (Pisum sativum L. var. arvense), derived from M0 seeds irradiated with 100 Gy, was evaluated for tolerance to D. pinodes (CBS 251.47) using a detached-leaf assay under controlled greenhouse conditions. Disease progression was quantified via image-based analysis on the 3rd and 5th days post-infection, calculating diseased area and disease severity index. Extensive phenotypic evaluation was also conducted on 16 families in the greenhouse and 100 families under field conditions, using an augmented incomplete block design. Screening revealed several M2 families with significantly improved tolerance compared to non-irradiated controls. Among these, some individuals combined enhanced resistance with improved yield-related traits, such as higher pod number and biomass, while others exhibited reduced agronomic performance. These findings highlight the phenotypic diversity induced by gamma irradiation and demonstrate the potential to generate dual-purpose pea genotypes with both disease resistance and enhanced productivity, providing valuable material for future breeding of resilient cultivars.