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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Plant Physiology and Genetics Research » Research » Publications at this Location » Publication #312007
Title: Simulating canopy temperature for modelling heat stress in cereals

Author
item WEBBER, H. - UNIVERSITY OF BONN
item EWERT, F. - UNIVERSITY OF BONN
item Kimball, Bruce
item SIEBERT, S. - UNIVERSITY OF BONN
item WHITE, JEFFREY
item Wall, Gerard - Gary
item OTTMAN, M.J. - UNIVERSITY OF ARIZONA
item TRAWALLY, D.N.A. - KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY
item GAISER, T. - UNIVERSITY OF BONN

Submitted to: Environmental Modelling & Software
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/3/2015
Publication Date: 12/25/2016
Citation: Webber, H., Ewert, F., Kimball, B.A., Siebert, S., White, J.W., Wall, G.W., Ottman, M., Trawally, D., Gaiser, T. 2016. Simulating canopy temperature for modelling heat stress in cereals. Environmental Modelling & Software. 7:143-155. doi: 10.1016/j.envsoft.2015.12.003.

Interpretive Summary: Crop growth models must be improved to account for the large effects of heat stress effects on crop yields. To date, most approaches in crop models use air temperature despite evidence that crop canopy temperature better explains yield reductions associated with high temperature events. This study presents a new model that calculates hour by hour the crop canopy temperature by solving complex equations that describe the balance of energy from solar radiation, evaporation, and other terms. The model was tested against canopy temperatures measured on irrigated wheat grown by ARS researchers in Arizona, as well as on corn grown in Burkina Faso. Crop development times calculated by the new model agreed well with those determined from observed canopy temperatures but not with those determined from air temperatures, which supports the claim that simulated canopy temperatures are needed in crop models to improve the simulation of heat stress events. This research will benefit all consumers of food and fiber.

Technical Abstract: Crop models must be improved to account for the large effects of heat stress effects on crop yields. To date, most approaches in crop models use air temperature despite evidence that crop canopy temperature better explains yield reductions associated with high temperature events. This study presents a canopy level energy balance using Monin-Obukhov Similarity Theory (MOST) with simplifications about the canopy resistance that render it suitable for application in crop models. The model is evaluated for irrigated wheat in Arizona and rainfed maize in Burkina Faso. No satisfactory single variable regression relationships for key explanatory variables were found that would justify using simpler empirical relationships. Finally, thermal times determined with simulated canopy temperatures were able to reproduce thermal times calculated with observed canopy temperature, whereas those determined with air temperatures were not. This evidence supports the claim that simulated canopy temperatures are needed in crop models to improve the simulation of heat stress events.