New Study Indicates C4 Crops Less Sensitive to Ozone Pollution Than C3 Crops

By Lisa Ainsworth

Ozone (O₃) in the troposphere negatively impacts crop growth and development, causing significant decreases in crop yield worldwide. This airborne pollutant does not come directly from smokestacks or vehicles, but instead is formed when other pollutants, mainly nitrogen oxides and volatile organic compounds, react in the presence of sunlight. In an increasingly polluted atmosphere, understanding what plants are tolerant of O₃ is critical to improving crop productivity and resilience.

In a collaboration between the Feedstock Production and Sustainability themes at the Center for Advanced Bioenergy and Bioproducts Innovation (CABBI), researchers have studied the effects of elevated O₃ on five C₃ crops (chickpea, rice, snap bean, soybean, wheat) and four C₄ crops (sorghum, maize, Miscanthus × giganteus, switchgrass). Their findings, published in Proceedings of the National Academy of Sciences (PNAS), indicate that C₄ crops are much more tolerant of high O₃ concentrations than C₃ crops.

“Understanding the tolerance of C₄ bioenergy crops to air pollutants will help us deploy them strategically across landscapes around the world,” said Lisa Ainsworth, Research Leader of the U.S. Department of Agriculture Agricultural Research Service’s (USDA-ARS) Global Change and Photosynthesis Research Unit and affiliate faculty in the Department of Crop Sciences in the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois.