Responses of crop yield and water productivity to stage-specific moisture anomalies under different precipitation scenarios

Wheat is the dominant crop in the North China Plain and is strongly affected by precipitation variability. Understanding how wheat yield and water productivity (WP) respond to precipitation anomalies at different growth stages is essential for improving yield stability under increasing climate variability. In this study, stage-specific moisture conditions were characterized using the standardized precipitation index (SPI). A set of precipitation-regulation scenarios was constructed to simulate moisture anomalies and evaluate their effects on wheat yield and WP using the APSIM model. The model performed well in simulating wheat yield and WP, with acceptable RMSE and NRMSE values. Under the historical climate baseline, wheat yield, WP, and wheat-season precipitation were 5279.72 kg ha⁻¹ , 1.839 kg m⁻³ , and 143.91 mm, respectively. Compared with the baseline scenario, the relative change in yield ranged from −15.40–5.86%, whereas WP varied from −13.65–2.94% across precipitation-regulation scenarios. Both crop yield and water productivity exhibited clear deviation under different precipitation anomaly scenarios, and their response intensity varied with moisture background and scenario type. The response per 10% change in wheat-season precipitation ranged from −6.70–8.25% for yield and from −2.69–3.57% for water productivity. Under drought conditions, increased rainfall mainly served to alleviate water limitation, but this was not observed in wet conditions. For water productivity, there were clear trade-off between wheat yield and water productivity under different precipitation scenarios. Besides, precipitation effects were strongly stage dependent, which the second key growth stage was the most sensitive period for the coordinated regulation of yield and water productivity, whereas the first stage had greater effects on stand establishment and yield stability, and the third stage was more vulnerable to excessive moisture. Compared with single-stage perturbations, multi-stage cumulative anomalies produced stronger and more complex impacts on wheat yield and water productivity.These findings highlight the importance of considering stage-specific precipitation anomalies and background moisture conditions when evaluating crop performance under climate variability. Overall, this study provides a scenario-based analytical framework for quantitatively assessing the responses of wheat yield and WP to stage-specific and multi-stage cumulative precipitation anomalies, thereby offering useful insights for agricultural water management and climate adaptation in the North China Plain.