Joint Ozone Pollution and Climate Warming Reduce Yield but Enhance Grain Protein Content in a Resistant Wheat Variety

Ozone (O₃) pollution and climate warming jointly threaten crop productivity and undermine global food security. However, their combined effects on wheat under real-world conditions are not well understood, limiting the potential for adaptation. Here, we investigated yield and grain protein of a major wheat variety under joint elevated O₃ and warming manipulations in 3 years (2021–2023), using a real-world simulation with a free-air controlled enrichment (FACE) facility. We found that O₃ pollution reduced grain yield mainly by limiting a carbon source via accelerated flag leaf senescence and declined leaf area index. Warming enhanced nitrogen uptake before heading and thereby mitigated leaf senescence and increased grain protein content. This wheat variety showed lower responses to independent elevated O₃ and warming than the varieties studied in the literature. Cultivating this tolerant wheat variety resulted in only 6% yield losses under joint O₃ pollution and warming, while increasing grain nitrogen content by 9%. These findings demonstrate that it is critical to breed wheat varieties that optimize high yield in tandem with adaptation to air pollution and climate change.