Enhancing salinity tolerance in rice using Saccharomyces cerevisiae inoculation: physiological and yield responses across diverse genotypes

Salinity stress is a major environmental constraint limiting crop productivity worldwide. The application of beneficial microorganisms is an effective strategy to improve plant tolerance to abiotic stresses. This study evaluated the role of Saccharomyces cerevisiae inoculation in enhancing physiological performance, oxidative stress tolerance, and yield of rice genotypes under saline-water irrigation. A lysimeter experiment was conducted during the 2024 and 2025 seasons. Five rice genotypes were exposed to saline water (6 000 ppm) with and without inoculation. Gas exchange, water status, oxidative stress markers, antioxidant enzyme activities, and yield-related traits were assessed. The results showed that inoculation significantly enhanced CO2 assimilation (12.27%), stomatal conductance (15.71%), transpiration rate (8.78%), and relative water content (16.36%) across both seasons. Furthermore, inoculation significantly reduced malondialdehyde (MDA) by 19.75% and hydrogen peroxide (H2O2) by 23.72%. While superoxide dismutase activity (SOD) increased by 35.32% and catalase activity (CAT) by 20.63%. Grain yield per plant improved by 18.91% and biological yield by 12.84%, accompanied by a reduction in grain sterility (14.47%). The assessed genotypes exhibited significant variation across all parameters studied. IRRI-165 and Giza-179 exhibited superior performance and responsiveness. Giza-182 and Sakha-104 displayed intermediate levels, while Giza-177 was the most sensitive genotype. Multivariate analyses confirmed strong positive associations between inoculation and genotypic performance. Whereas genotypic performance was negatively associated with oxidative stress markers. These results suggest that S. cerevisiae inoculation improves rice performance under salinity stress. The enhancement may contribute to the integration of physiological and biochemical mechanisms. Therefore, combining microbial inoculation with tolerant genotypes providesa sustainable strategy to improve rice productivity in salt-affected environments.