Optimizing wheat yield and water productivity under water scarcity: A modeling approach for irrigation and cultivar selection across different agro-climatic zones of Egypt

Egypt, a major wheat importer, grapples with significant food security concerns exacerbated by limited water resources and climate variability. This study investigates strategies to optimize wheat yield and water productivity across Egypt’s diverse agro-climatic zones through precise irrigation management and cultivar selection. Using the DSSAT CERES-Wheat model, calibrated with field data from experiments on three wheat cultivars (Sakha94, Shandweel1 and Sids1) under five irrigation treatments across four locations, we evaluated the impact of irrigation frequency and elevated CO₂ levels (390 ppm) on grain yield and water-use efficiency. Results show that frequent irrigation (50 % depletion) increases yield by up to 22 % compared to less frequent irrigation (90 % depletion), particularly for Sakha94, while reduced irrigation enhances water productivity based irrigation (WP_Irrigation), with Shandweel1 and Sids1 achieving 15–20 % higher WP under water-limited conditions. Elevated CO₂ contributes a modest yield increase of approximately 5 % and enhances WP, indicating potential adaptive benefits in future high-CO₂ scenarios. Sensitivity analysis revealed that moderate CO₂ enrichment (+420–440 ppm) combined with + 1°C to + 2°C increases yield and WP by 10–25 %, but higher temperatures (+3°C) shortened growth cycles and reduced benefits, particularly for heat-sensitive cultivars like Sakha94. Linear mixed model analysis further reveals distinct fixed and random effects, underscoring that strategic irrigation management can effectively balance yield maximization and water conservation. These findings highlight the necessity of location-specific irrigation and cultivar strategies to alleviate water scarcity. Future research should prioritize a multi-model ensemble approach to quantify uncertainties, integrate CMIP6 climate projections and explore multi-factor environmental impacts, supporting sustainable wheat production in water-limited regions.