Canopy temperature for simulation of heat stress in irrigated wheat in a semi-arid environment: a multi-model comparison

Authors: WEBBER, HEIDI - University Of Bonn; MARTRE, PIERRE - Institut National De La Recherche Agronomique (INRA); ASSENG, SENTHOLD - University Of Florida; Kimball, Bruce; White, Jeffrey; Wall, Gerard - Gary; OTTMAN, MICHAEL - University Of Arizona; DE SANCTIS, GIACOMO - European Commission-Joint Research Centre (JRC); DOLTRA, JORDI - Center For Agricultural Research And Training, Cantabria Government (CIFA); GRANT, ROBERT - University Of Alberta; KASSIE, BELAY - Aarhus University

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2015
Publication Date: 1/30/2017
Publication URL: http://handle.nal.usda.gov/10113/5426093
Citation: Webber, H., Martre, P., Asseng, S., Kimball, B.A., White, J.W., Wall, G.W., Ottman, M., De Sanctis, G., Doltra, J., Grant, R., Kassie, B. 2017. Canopy temperature for simulation of heat stress in irrigated wheat in a semi-arid environment: a multi-model comparison. Field Crops Research. 202:21-35.

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 the fact that crop canopy temperatures can deviate significantly from air temperature, especially becoming higher than air temperature when crops are under water stress. In this study, six wheat growth models which compute canopy temperature were tested against canopy temperatures measured on irrigated wheat grown by ARS researchers in Arizona. Three models that were most mechanistic did the best job at predicting canopy temperatures, but they were no better at predicting wheat yields, indicating that more model development needs to be done to improve the simulation of processes leading to the production of grain yield. This research will benefit all consumers of food and fiber.

Technical Abstract: Mounting evidence suggests that even brief periods of high temperatures occurring around flowering and during grain filling can severely reduce grain yield in cereals, a phenomenon referred to as heat stress. Recently, ecophysiological models of crops models have begun to represent such phenomena. Most models use air temperature (Tair) in their heat stress responses despite evidence that crop canopy temperature (Tc) better explains yield losses. Tc can deviate significantly from Tair based on climatic factors and the crop water status. The broad objective of this study was to evaluate whether simulation and use of Tc improves the ability of models to simulate heat stress impacts on wheat under irrigated conditions. Nine process-based models, each using one of three broad approaches (empirical, EMP, energy balance assuming neutral atmospheric stability, EBN, and energy balance correcting for the atmospheric stability conditions, EBSC) to simulate Tc, simulated grain yield under a range of temperature conditions. The models varied widely in their ability to reproduce the observed Tc with the commonly used EBN models performing much worse than either EMP or EBSC. Use of Tc to account for heat stress effects did improve simulations compared to using only Tair to a relatively minor extent, but use of Tc on more processes did not imporve yield simulations. Models that simulated yield well under heat stress had varying skill in simulating Tc, highlighting the need to more systematically understand and model heat stress events in wheat.