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ARS Home » Research » Publications at this Location » Publication #116316
Title: MODELLING THE EFFECTS OF CO2 AND DROUGHT ON WHEAT FOR DIFFERENT CLIMATIC CONDITIONS AND CULTIVARS

Author
item EWERT, F - DEPT OF AGRI SCI DENMARK
item RODRIGUEZ, D - WAGENINGEN AGRI UNIV
item JAMIESON, P - NZ INST CROP & FOOD RES
item SEMENOV, M - UNIV OF BRISTOL UK
item MITCHELL, R.A. - BIOCHEM & PHYSIO DEP UK
item GOUDRIAAN, J - WAGENINGEN AGRI UNIV
item PORTER, J - DEP AGRI SCI DENMARK
item Kimball, Bruce
item Pinter Jr, Paul
item MANDERSCHEID, R - INST AGROECOLOGY GERMANY

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2001
Publication Date: 3/15/2002
Citation: Ewert, F., Rodriguez, D., Jamieson, P., Semenov, M.A., Mitchell, R.C., Goudriaan, J., Porter, J.R., Kimball, B.A., Pinter Jr, P.J., Manderscheid, R. 2002. Modelling the effects of co2 and drought on wheat for different climatic conditions and cultivars. New Phytologist. 93:249-266.

Interpretive Summary: The carbon dioxide (CO2) concentration in the atmosphere is increasing and expected to double near the end of this century. The elevated levels of CO2 affect plant photosynthesis and also cause a partial closure of the stomata in plant leaves through which the plant exchanges CO2 and water vapor with the atmosphere. The magnitude of both effects and the extent to which they change growth, yield, and water requirements of crops are likely to be influenced by other environmental factors such as soil water supply. To predict the effect of the elevated CO2 on future crop production and to aid in developing improved management strategies, crop growth simulation models are being developed. This paper reports a successful test of three such models called AFRCWHEAT2, LINTULCC2, and SIRIUS, which have varying levels of detail in their handling of physiological processes. Model predictions are compared to observed results from experiments using open-top CO2-enrichment chambers in Germany and from open-field free-air CO2-enrichment (FACE) experiments in Arizona, USA. Most model results were acceptably close to observed values, especially for the FACE data, predicting for example, that CO2 concentrations such as expected near the end of this century should cause wheat grain yields to increase 20-30% with ample water and even more under water-stress conditions. This work will benefit future growers and consumers of wheat and wheat products.

Technical Abstract: Effects of increasing CO2 concentration on wheat vary depending on water supply and climatic conditions, which are difficult to estimate. Three existing crop simulation models that differ in structure and mechanistic detail were modified (AFRCWHEAT2, LINTULCC2, IRIUS) to simulate growth and yield of spring wheat in response to elevated CO2, drought, and climatic conditions. Simulations were compared with observations from two years of FACE experiments with spring wheat cv. Yecora Rojo in Maricopa, Arizona, and two years of open-top chamber (OTC) experiments with spring wheat cv. Minaret in Braunschweig and Giessen, Germany. Simulations of all models were satisfactory for biomass, grain yield, ET, and WUE of wheat grown in the FACE experiments. Simulations were less accurate for OTCs, which was partly due to the heterogeneity between OTC experiments. However, there were differences between model simulations. Effects of CO2 on wheat were more pronounced under drought as compared to well-watered conditions in most OTC experiments, and simulations were particularly unsatisfactory when this interaction was not accounted for in the model. In a simulation exercise, grain yield of spring wheat grown in southern Spain was simulated to increase by about 30 to 80 % due to doubling CO2 depending on seasonal rainfall. Further analysis suggested that responses of wheat to combined changes in CO2, water supply, and climatic conditions can be simulated using relatively simple assumptions about crop assimilation and transpiration as long as the relevant response mechanisms are accounted for.