Optimization of Wheat (<i>Triticum aestevum L.)</i> Water Productivity Under Deficit Furrow Irrigation Using AquaCrop Model

Crop growth models like AquaCrop maximize crop output and water use efficiency by forecasting agricultural indicators including crop yield, dry biomass, and water productivity. This study not only validated and calibrated the AquaCrop model, but also investigated the effects of deficit irrigation on wheat yield and water productivity. The experiment was conducted for calibration in 2022-2023 and for validation in 2023-2024. Five irrigation treatments were utilized in this study: 100% ETc, 80% ETc, 80% ETc at development and mid-stage, 60% ETc, and 60% ETc at development and mid-stage. The test variety was the Kingbird local wheat variety. Applying 100% ETc produced the maximum plant height, biomass, yield, and thousand seed weight (66.97cm, 36.43g, 3.47t ha<sup>-1</sup>, 9.53t ha<sup>-1</sup>), while 60% ETc produced the lowest values (63.1cm, 30.4g, 1.94t ha<sup>-1</sup>, and 7.74t ha<sup>-1</sup>). The best water productivity of 0.92kg m<sup>-3</sup> was seen throughout the development and mid-stages when 80% ETc was applied. The AquaCrop model's root mean square error ranged from 0.002 to 0.25 t ha<sup>-1</sup>, its model efficiency ranged from 0.81 to 0.95, and its coefficient of determination for grain yield, dry biomass, and water productivity ranged from 0.84 to 0.98. Model efficiency was 0.83, 0.85, and 0.77, yield, biomass, and water productivity had coefficients of determination of 0.96, 0.93, and 0.73, and the AquaCrop model's root mean square error was 0.244, 0.413t ha<sup>-1</sup>, and 0.03kg m<sup>-3</sup>, respectively. When 60% ETc was used, the largest prediction error of 17.36 was observed under yield, while when 100% crop water requirement was applied, the lowest prediction error of 0.26 was obtained under biomass. Therefore, it can be concluded that the AquaCrop model can reliably forecast crop metrics that are impacted by different watering schedules.