Improvement of salt stress tolerance in sugar beet: role of gamma irradiation and cultivar-specific responses

This study investigates the effects of salt stress and gamma irradiation on growth, biochemical, and physiological responses in three sugar beet (Beta vulgaris L.) cultivars. Control plants were irrigated with fresh water (EC = 1.1 dS/m), whereas salt stress was imposed with an irrigation of 9 dS/m. Seeds were irradiated with gamma rays (0, 50, 100, 200, 400 Gy) before sowing. Exposure to salt stress reduced root yield (RY), sugar yield (SY), chlorophyll content, and antioxidant enzyme activities (catalase (CAT) and superoxide dismutase (SOD)). In contrast, oxidative damage increased, as indicated by elevated malondialdehyde (MDA) concentrations. Interestingly, salt stress enhanced sugar content, with the Eudoro cultivar showing the greatest resilience, maintaining higher RY and SY and lower MDA compared to the other cultivars. Gamma irradiation at moderate doses (50-200 Gy) alleviated the effects of salt stress, with the strongest improvements in SY observed at 100 and 200 Gy. These treatments enhanced RY, chlorophyll content, and antioxidant activities, while also improving photosynthetic efficiency (Fv/Fm) and cellular integrity. Higher doses (> 200 Gy) reduced sugar content, indicating dose-specific effects. Eudoro exhibited superior salt tolerance, maintaining higher root and sugar yields (RY, SY) and reduced oxidative damage (lower MDA) under salt stress. These findings demonstrate that gamma irradiation at optimal doses enhances salt tolerance in sugar beet, offering cultivar-specific benefits for breeding programmes in saline environments.