Production potential and water productivity of oilseed rape in Egypt – Insights from a multi-environment simulation study using the CROPGRO model

Oilseed rape (OSR; Brassica napus), also known as rapeseed or canola, is an important global oil crop with potential to reduce Egypt's large edible oil deficit. To support its introduction as a new crop in Egypt, reliable information on yield potential, irrigation requirements, and optimal sowing windows is required. In this study, six field experiments conducted across different agro-climatic regions were used to adapt, calibrate, and evaluate the CROPGRO model within the Decision Support System for Agrotechnology Transfer (DSSAT) framework for simulating OSR phenology, growth, and yield. The calibrated model was subsequently applied to simulate OSR production at five locations in Egypt using site-specific soil and weather data. Eight sowing dates ranging from mid-September to early January and two irrigation strategies (fixed schedules vs. automatic irrigation triggered by soil water thresholds) were evaluated over a 30-year period (1991–2020). Model evaluation showed strong agreement between simulated and observed variables, with d‐index values ranging from 0.91 to 0.95 for phenology, biomass, and yield. Long-term simulations indicated that OSR production is feasible across all studied regions, with average seed yields ranging from 1.9 to 3.1 Mg ha⁻¹ under optimal sowing conditions. Optimal sowing windows varied geographically from early October in southern Egypt to mid-November in northern regions. The calibrated model provides a useful decision-support tool for optimizing sowing dates and irrigation management to improve OSR productivity and water use efficiency in Egypt. • The CROPGRO model was calibrated and evaluated using multi-environment trials in Egypt. • Model adjustments improved simulation of phenology and seed yield across sowing dates. • The model captured G × E × M interactions of oilseed rape under Egyptian conditions. • Mixed-effect models showed strong effects of sowing date and irrigation on seed yield. • Optimal sowing windows: early Oct (south) to mid-Nov (north) for high yield and WP.