Project Number: 6645-11000-007-00
Project Type: Appropriated

Start Date: May 20, 2005
End Date: May 19, 2010

Objective:
Quantify the combined effects of elevated carbon dioxide and ozone concentrations on soil carbon dynamics in a soybean-wheat field crop system; quantify the effects of temperature on the physiology, biomass production and seed yield of selected crop plants under conditions of elevated carbon dioxide and ozone; and identify soybean germplasm with enhanced growth and yield potential under elevated levels of carbon dioxide and ozone, and determine the underlying mechanisms and associated genes that control plant responses to these gases. Application of results from this research in models and decision support systems will ultimately support management strategies that optimize sequestration of carbon in agricultural soils to offset carbon dioxide emissions. Research results should also aid in the development of crops that tolerate ozone and utilize carbon dioxide more effectively.

Approach:
Research will be conducted using field and greenhouse chambers for control of ozone and carbon dioxide concentrations and temperature. Effects on yield, development, and quality for specific crops (e.g. soybean, snap bean, wheat and selected forages) and on changes in soil carbon will be tested. To evaluate the interactive effects of ozone, carbon dioxide, and temperature on plants, studies will include measurements of leaf conductance, photosynthesis, chlorophyll fluorescence, carbon metabolism, and biochemical systems that detoxify reactive oxygen intermediates formed from ozone. To evaluate the effects on agricultural soils, studies of plant response to ozone and carbon dioxide will be accompanied by measurements of soil microbial biomass, microbial community structure, and microbial activity, soil carbon distribution among carbon pools, soil carbon turnover using delta 13C mass spectrometry, and nitrogen mineralization. Genetic variability of response to ozone and carbon dioxide will be assessed through a combination of screening and pedigree analysis. Development and testing of Arabidopsis mutants will be conducted to identify genes associated with plant response to ozone.