Courtesy Hemera/Thinkstock Scientists at Fresno State have found evidence that applications of carbon dioxide gas could improve tomato growth in greenhouses.

Specially equipped greenhouses hosted a first-of-its-kind agricultural experiment on the Fresno State Agricultural Laboratory campus farm when carbon dioxide gas was applied to tomato plants to determine whether production could be enhanced.

Leading the work is Florence Cassel Sharma, a soil and plant scientist conducting research for the Center for Irrigation Technology. Cassel Sharma recently received the Far West Region 2011 Outstanding Partnership Award presented by the Federal Laboratory Consortium.

“The main goal of this project is to provide efficient and simple techniques for recycling CO₂ emissions in agricultural fields to enhance crop productivity and water-use efficiency,” Cassel Sharma says.

Primary producers of CO₂ in California are the transportation sector, power and cement plants, and oil refineries, Cassel Sharma notes. Although CO₂ has different industrial applications (carbonation, food preservation and packaging), commercial uses of the compound are relatively small compared to the amount produced.

“A novel use of these emissions could be found in the agricultural sector since CO₂ is the primary component of photosynthesis and, therefore, plant growth,” Cassel Sharma says. “Application of CO₂ around the crop canopy could enhance photosynthesis and thus increase crop productivity and water-use efficiency.”

Previous CIT studies indicate that CO₂ enrichment of open-field crops has a good chance of success, according Dr. Dave Goorahoo, PhD, an assistant plant science professor at Fresno State and a co-investigator on the project. Increased yields were observed on tomatoes, bell peppers and strawberries, he says.

In the most recent study, conducted during the 2011 summer growing season, researchers applied CO₂ and irrigation water at different levels in open-top chambers that resemble greenhouses. CIT research associate Shawn Ashkan, also working on the project, designed and supervised the construction of the chambers and CO₂ delivery system.

Plants were sampled regularly during the growing season and measured for leaf area, nutrient content and weight. Photosynthesis measurements were taken for each CO₂ and irrigation treatment. Tomatoes from the different treatment groups were harvested in September 2011. Yields were measured along with plant and root biomass. Similar treatments will be applied during the second year of the project, in summer 2012. Results will be released following second-year analysis.

Funding for this research was provided by the California State University Agricultural Research Institute.