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Corn and other crops are not adapted to benefit from elevated carbon dioxide levels

The U.S. backs out of the Paris climate agreement even as carbon dioxide (CO2) levels continue to rise. Through photosynthesis, plants are able to turn CO2 into yield. Logic tells us that more CO2 should boost crop production, but a new review, involving co-author Stephen Long, the Stanley O. Ikenberry Chair Professor of Plant Biology and Crop Sciences, from the University of Illinois shows that some crops, including corn, are adapted to a pre-industrial environment and cannot distribute their resources effectively to take advantage of extra CO2.

Most plants (including soybeans, rice, canola, and all trees) are C3 because they fix CO2 first into a carbohydrate containing three carbon atoms. Corn, sorghum, and sugarcane belong to a special group of plants known as C4, so-called because they first fix CO2 into a four-carbon carbohydrate during photosynthesis. On average, C4 crops are 60 percent more productive than C3 crops.

When crops are grown in elevated CO2 that mimic future atmospheric conditions, research shows that C3 crops can become more productive while some experiments suggest that C4 crops would be no more productive in a higher CO2 world.

"As scientists, we need to think several steps ahead to anticipate what the Earth will look like five to 30 years from now, and how we can design crops to perform well under those conditions," said Charles Pignon, a former postdoctoral researcher at Illinois. "We decided that a literature review and a retrospective analysis of biochemical limitations in photosynthesis would be able to give us some insight into why C4 crops might not respond and how we might alter this."

The literature review, published in Plant, Cell & Environment, was supported by Water Efficient Sorghum Technologies (WEST), a research project that aimed to develop bioenergy crops that produce more biomass with less water, with funding from the Advanced Research Projects Agency-Energy (ARPA-E).

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Publication Date: 11/05/2020
Photo credits: College of ACES (Agronomy Day 2017)
Editor: Carl R. Woese Institute for Genomic Biology