Delaying sowing time and increasing sowing rate with plastic mulching can enhance wheat yield and water use efficiency under future climate change

Adjusting sowing dates and rates are effective measures for winter wheat to adapt to future climate change in achieving high yields. However, the combined influence of sowing date and sowing rate on winter wheat yield and water use efficiency (WUE) under plastic mulching (PM) conditions, particularly in the context of climate change, remains unexplored. To address this, a two-year field experiment conducted in the Guanzhong Plain, Northwest China, was used to calibrate the SPACSYS model. The calibrated model, driven by 27 global climate models under SSP245 and SSP585 scenarios, was used to project changes in yield and WUE and to evaluate the potential of various management strategies for mitigating the adverse effects of climate change. We investigated multiple strategies, including two mulching methods [plastic mulching (PM) and no mulching (NM)], six sowing rates (R1: local; R2: 110 % R1; R3: 120 % R1; R4: 130 % R1; R5: 140 % R1; R6: 150 % R1), and four sowing dates (10-day early, normal sowing, 10-day delay, 20-day delay). Results showed that without adaptation, the simulated yield under local management options (NM+normal sowing date+R1 sowing rate) decreased by 14.9-26.7 % under SSP245 and by 24.5-39.5 % under SSP585. Similarly, WUE decreased by 10.4-12.5 % under SSP245 and by 3.2-7.0 % under SSP585. These reductions in yield were primarily attributed to rising temperatures and decreasing radiation, while the decline in WUE was mainly driven by rising temperatures. In contrast, the optimal management combination (PM+10-day delayed sowing+R5 sowing rate) resulted in yield increases of 26.0-34.7 % under SSP245 and 21.2-32.5 % under SSP585 compared to the local management during the baseline period. This strategy also achieved the highest WUE, improving by 31.0-32.7 % under SSP245 and 36.5-39.2 % under SSP585 relative to the baseline. These findings provide valuable information to help farmers in Northwest China adapt to future climate change by optimizing sowing time and rate with PM, thereby enhancing wheat yield and WUE.