Water Use Under Increased Aridity and CO2 O3 Concentrations

Project Number:

02R-13

Project Duration:

30 months

Dates:

May 1, 2002 to October 31, 2004

Institution of Principle Investigator while on this project:

University of Illinois

Investigators (most current known information)

Ort, Donald R. (PI)

Professor, Department of Plant Biology, University of Illinois, 190 ERML 1201 W. Gregory Dr., Urbana IL 61801

TEL: +1-217-333-2093, FAX: +1-217-244-0656, Email: d-ort@uiuc.edu

Long, Stephen P.

Professor, Departments of Plant Biology and Crop Science, University of Illinois, 190 ERML 1201 W. Gregory Dr., Urbana IL 61801, USA

TEL: +1-217-333-2487, FAX: +1-217-244-7563, Email: stevl@life.uiuc.edu

Shahak, Yosepha

Institute of Horticulture, ARO The Volcani Center, PO Box 6, Bet-Dagan 50250, Israel

TEL: +972-3-968-3766, FAX: +972-3-966-9583, Email: y_shahak@netvision.net.il

Proposal Abstract

In our previous reports we have described the results of a range of experiments on plant water relations of both soybean and corn under experimental treatments simulating scenarios of future global climate change. Our publication, Will photosynthesis of maize (Zea mays) in the US Corn Belt increase in future [CO₂] rich atmospheres? An analysis of diurnal courses of CO₂ uptake under free-air concentrations enrichment (FACE), was published in Global Change Biologyin June 2004. This reported that, contrary to hypothesis, C₄ photosynthesis was stimulated by growth at elevated [CO₂] under field conditions. Importantly, the stimulation of photosynthesis by elevated [CO₂] was only observed during periods of drought stress. This was consistent with, but did not demonstrate unequivocally, the hypothesis that elevated CO₂ cannot stimulate C₄photosynthesis directly, but does lower stomatal conductance – reducing plant water use and ameliorating drought stress. This has obviously important implications for the C₄ species which dominate arid grassland ecosystems. In 2004, our aim was to continue this work and improve our mechanistic understanding of the response.