Modeling the effects of tropospheric ozone on the growth and yield of global staple crops with DSSAT v4.8.0

Abstract. Elevated surface ozone (O₃) concentrations can negatively impact growth and development of crop production by reducing photosynthesis and accelerating leaf senescence. Under unabated climate change, future global O₃ concentrations are expected to increase in many regions, adding additional challenges to global agricultural production. Presently, few global process-based crop models consider the effects of O₃ stress on crop growth. Here, we incorporated the effects of O₃ stress on photosynthesis and leaf senescence into the Decision Support System for Agrotechnology Transfer (DSSAT) crop models for maize, rice, soybean, and wheat. The advanced models reproduced the reported yield declines from observed O₃-dose field experiments and O₃ exposure responses reported in the literature (O₃ relative yield loss RMSE < 10 % across all calibrated models). Simulated crop yields decreased as daily O₃ concentrations increased above 25 ppb, with average yield losses of 0.16 % to 0.82 % (maize), 0.05 % to 0.63 % (rice), 0.36 % to 0.96 % (soybean), and 0.26 % to 1.23 % (wheat) per ppb O₃ increase, depending on the cultivar O₃ sensitivity. Increased water deficit stress and elevated CO₂ lessen the negative impact of elevated O₃ on crop yield, but potential yield gains from CO₂ concentration increases may be counteracted by higher O₃ concentrations in the future, a potentially important constraint to global change projections for the latest process-based crop models. The improved DSSAT models with O₃ representation simulate the effects of O₃ stress on crop growth and yield in interaction with other growth factors and can be run in the pDSSAT global gridded modeling framework for future studies on O₃ impacts under climate change and air pollution scenarios across agroecosystems globally.