8 The Business of Prairie Agriculture Better Farming | January 2024 C4 CROPS & OZONE POLLUTION ‘It is difficult to compare the response of C3 & C4 crops to ozone in the field.’ By April Wendling 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 (soybean, wheat, chickpea, rice, snap bean) and four C4 crops (sorghum, maize, Miscanthus × giganteus, switchgrass). Their findings, published in the 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,” says Lisa Ainsworth, research leader in the Global Change and Photosynthesis Research Unit in the United States Department of Agriculture’s Agricultural Research Service (USDA-ARS) agency, and adjunct professor of plant biology at the University of Illinois. Both C3 and C4 crops are major sources of food, bioenergy and ethanol production worldwide. The difference between C3 and C4 plants lies in the carbon-fixation pathway they use during photosynthesis: C3 plants convert CO2 and sunlight into a three-carbon molecule, whereas the first photosynthesis product of C4 plants is a four-carbon molecule. Additionally, the C4 photosynthesis pathway starts in mesophyll cells that comprise the surface of the leaf, and then moves into bundle sheath cells that are deeper in the plant. This spatial separation is not present in the C3 photosynthesis pathway. Scientists have historically assumed that C4 plants are less sensitive to O3 pollution than C3 plants, but that assumption had not been thoroughly researched until this study. “Variation in size and growing season length means that it is difficult to do side-by-side comparisons of the response of C3 and C4 crops to ozone in the field” says Shuai Li, primary author on the paper and a postdoc in CABBI. “This limits accurate comparisons of the O3 sensitivity of C3 and C4 crops.” By synthesizing available literature Research C4 Crops like sorghum are more tolerant of high O3 concentrations. mailsonpignata - stock.adobe.com … the top producers across the Prairies for just PENNIES per adult reader! Paul.Nolan@Farms.com ADVERTISERS REACH ...
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