Climate change is expected to increase yield and water use efficiency of wheat in the North China Plain

Climate change impacts on winter wheat yield and water-use were assessed with the AquaCrop model for different representative concentration pathway (RCP) scenarios (RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5) and time slices (2040s, 2060s, 2080s) using ensemble projections from 10 general circulation models (GCM) for a site in the North China Plain. To test the role of crop and soil management practices under climate change, simulations with deficit irrigation (DI) and mulching were also performed. DI was defined as a practice where soil water content was restored to field capacity after depleting 150% of readily available water (RAW). The chosen mulching practice had a fixed capacity to reduce evaporation by 60%. Simulated outputs were compared with the baseline simulations (baseline period: 1984-2015). The results indicate that yield and water use efficiency (WUE) of wheat will increase under all RCP scenarios and time slices. Analysis revealed that winter wheat in the NCP would benefit from both CO2 fertilization and warming. Warming will shorten the growing cycle but largely due to curbing of the overwintering period. Due to accelerated growth/development, flowering and maturity will be advanced compared to the baseline period. Warming will also ease the low-temperature stress on biomass production. The seasonal evapotranspiration will reduce mainly due to the shorter growing cycle and the CO2-induced reduction in transpiration. Increase in yield and WUE is expected even under DI, while mulching can further increase WUE. Projections using individual GCMs indicated that the variability in crop production would be higher for the high-end scenario (RCP 8.5) than for RCP 2.6. These findings imply that in general, wheat in the NCP is less vulnerable to climate change than in other parts of the world. In addition, the expected increase in the yield and WUE of wheat may positively affect current depletion rates of groundwater for irrigation; however, more work is needed to quantify this. In future, it will be possible to introduce short duration wheat and long duration maize (second crop in rotation) cultivars.