Modeling the impacts of ozone deposition on wheat yields

 In recent years, there has been a growing concern about the impacts of ozone pollution on crop
production, particularly in peri-urban cropping areas. As an oxidant, ozone affects plant
biochemical and physiological processes, which in turn disrupt crop development and result in
yield losses. Wheat, a staple crop that sustains billions of people worldwide, is particularly
susceptible to ozone pollution. Quantifying the effects of ozone on wheat yields is crucial for
shaping agronomic and environmental policies at both national and European levels, not only
for the present but also for future scenarios involving climate change, air quality, and
agricultural land management. Another key element to consider is the effect of ozone on soil
organic carbon sequestration in croplands. Crop models play a vital role in quantifying the
combined effects of ozone and management practices on crop growth, yield, biomass
accumulation, and soil carbon dynamics.
The CERES-O3 model developed in 2005 which extends from the CERES-EGC crop model
by integrating Farquhar’s photosynthesis model, efficiently fulfills these requirements.
CERES-O3 simulates the effects of elevated ozone concentrations on photosynthetic rates,
including Rubisco carboxylation efficiency, and consequently on biomass production and
yields.
We use new sets of experimental data obtained at the Grignon ICOS (Integrated Carbon
Observation System) site under varying pedoclimatic conditions against experimental data from
the literature to evaluate the model’s performance. Model simulations reveal that elevated
ozone concentrations reduce photosynthetic rates, stomatal conductance, and Rubisco
carboxylation efficiency, culminating in diminished biomass and grain yield. Furthermore,
parameterizations for two wheat cultivars (Premio and Soissons) show similar ozone effects on
both cultivars.
Although developed more than 20 years ago, CERES-O3 remains a promising tool to quantify
current and predict future ozone impacts at local and global scales. It has strong potential to
enable the exploration of mitigation strategies, including cultivar development, improved
agronomic practices, and policy interventions to curb ozone pollution. It can be used to better
understand the combined effects of ozone pollution and climate stress, which are essential for
ensuring food security in changing global environments. Future steps regarding the model
involve assessing the potential impacts of ozone on soil carbon sequestration in croplands,
which remains a little-known factor in nature-based solutions to mitigate climate change.
Keywords: Ozone, wheat, crop yield, photosynthesis, modeling, stomatal conductance,
CERES-O3