Optimizing winter wheat varieties for yield and net ecosystem productivity under climate change in the North China Plain

Global warming presents significant challenges to crop production, but the emphasis on future yields rather than carbon sequestration has limited our understanding of how cropland contributes to climate change. In this study, we integrated the World Food Studies model and the Boreal Ecosystem Productivity Simulator to evaluate the impacts of variety optimization on winter wheat yield and net ecosystem productivity (NEP) in the North China Plain under future climate change. Without variety optimization, winter wheat yield was projected to decline by an average of 9.1 % and 11.9 % under SSP245 and SSP585, respectively, while NEP was expected to increase, particularly under SSP585. Both flowering and maturity dates advanced, shortening the vegetative growth stage (VGS) while maintaining a relatively stable reproductive growth stage (RGS). With variety optimization, winter wheat showed reduced climate sensitivity, with yield projected to increase by an average of 20.7 % and 16.9 % under SSP245 and SSP585, respectively, and NEP generally increased. However, certain regions in Hebei and Shandong may transition from carbon sinks to sources when grain carbon content is considered. Additionally, flowering advanced more significantly than maturity, extending the duration of RGS. Our findings highlight the critical role of phenology in regulating winter wheat yield and NEP, particularly emphasizing the stronger influence of climatic conditions during VGS compared to RGS. Model results suggest future variety optimization strategies should reduce heat requirements during VGS and increase them during RGS.