A graduate student at The University of Toledo recently won an award from the Ecological Society of America for his study that shows why the combination of high carbon dioxide levels in the air and chronic global warming will contribute to a decrease in crop production and food quality during the next few decades.

“We have provided a better understanding of what scientists need to do to improve the heat tolerance of crops in the future,” said Dileepa Jayawardena, a PhD student in the Department of Environmental Sciences who conducted the climate change study as a project for his master’s degree. “They can use this information to generate new climate-change-tolerant crops to help feed the growing human population.”

Using tomato as a model, Jayawardena investigated the way plants absorb nitrogen fertilizer from the soil.

Over the course of 18 days inside controlled growth chambers at Bowman-Oddy Laboratories, Jayawardena’s team subjected the plants to conditions that mimic future climate.

Individually, elevated carbon dioxide and warming did not have large effects on tomato responses.

However, when combined, researchers saw a large decrease in the uptake rate of soil nitrate and ammonium through the roots. At the same time, researchers saw a significant drop in the concentration and function of the proteins that roots use to acquire soil nitrogen. The result was a crop with lower nitrogen levels and thus lower nutritional value.

Jayawardena’s work also shows that the combination of heat and carbon dioxide is bad for the plant in terms of being able to convert inorganic nitrogen, like nitrate and ammonium, into organic form, like protein, which is the form of nitrogen that humans require.

“If climate change intensifies, this impact on plant nitrogen concentration means that plants will not grow as big in the future, and they will be poorer-quality food for people and other animals that eat plants,” Jayawardena said.

Jayawardena won the New Phytologist Poster Award for his presentation at the Ecological Society of America annual meeting last month in Florida. It is the nation’s largest organization of professional ecologists with a membership of more than 10,000 scientists.

“By itself, increases in atmospheric carbon dioxide levels tend to increase plant growth, which is a positive,” said Scott Heckathorn, UT ecology professor and Jayawardena’s faculty advisor. “However, increasing carbon dioxide is the primary cause of current global warming, which will increase heat stress for much life on the planet. The question then arises as to whether benefits of elevated carbon dioxide will offset the negative effects of increasing heat stress. What is new about Dileepa’s work is that it provides a mechanism for why the combination of elevated carbon dioxide and heat is detrimental.”

The research was funded by the U.S. Department of Agriculture.

Tags: College of Natural Sciences and Mathematics