Joint impacts of ozone pollution and climate change on yields of Chinese winter wheat

Ozone (O-3), soil water deficit, and climate warming affect crop yields, but previous studies examined the individual effects of these stressors on only specific crops at some regions. The combined effects of these stressors on crop yields can reveal more environmentally realistic impacts, but relevant studies are scarce. Here, we used statistical modeling based on historical data to assess the joint impacts of O-3, agricultural drought (evapotranspiration deficit index, ETDI), and maximum air temperature (T-max) on actual yields of winter wheat in main production areas in China. We found that the negative effects of ETDI and T-max were weakening due to wetting and warming during 1982-2012. However, the O-3-induced yield loss for winter wheat was 8.02% (95% CI: 2.97%-14.35%), including the O-3-T-max and O-3-ETDI interaction effects in the model. O-3-T-max interaction significantly resulted in a median yield loss of 3.08% (95% CI: 0.33%-7.47%), whereas no significant yield loss was induced by O-3-ETDI interaction. The results suggest that T-max worsens the negative effect of O-3. To protect against such O-3-driven yield losses, reducing O-3-precursor emission and breeding more heat-tolerant and O-3 resistant cultivars are needed to increase world grain production.