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Title: Simulating canopy transpiration and photosynthesis of corn plants under contrasting water regimes using a coupled model

Author
item YANG, YANG - University Of Maryland
item KIM, SOO-H - University Of Washington
item Timlin, Dennis
item Fleisher, David
item QUEBEDEAUX, BRUNO - UNIV OF MD
item Reddy, Vangimalla

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2009
Publication Date: 6/30/2009
Citation: Yang, Yang, Kim, Soo-H, Timlin, D.J., Fleisher, D.H., Quebedeaux, B., Reddy, V. 2009. Simulating canopy transpiration and photosynthesis of corn plants under contrasting water regimes using a coupled model. Transactions of the ASABE. 52(3):1011-1024.

Interpretive Summary: Water is necessary for plant growth and development but is a limited and sometimes expensive resource. Agricultural managers need improved tools to manage and assess water use by crops, especially corn. One such tool is a computer simulation model of crop growth where a computer program can predict crop growth and yield given environmental information. Most simulation models available today, however, use highly empirical approaches and do not accurately mimic the effects of reduced water availability on crop yields. We developed an improved model that incorporates recent research findings and gives better and more robust estimates of growth and development of corn under drought stress. This new model will be a valuable tool in studying corn water uptake under drought stress and also provides a platform to implement and evaluate water dynamics and CO2 uptake in a corn crop in global climate change studies.

Technical Abstract: A process-based corn simulation model (MaizeSim) was coupled with a two-dimensional soil simulator (2DSOIL) to simulate the transpiration and photosynthesis of corn under drought stress. To simulate stomatal reaction to drought stress, two stomatal controlling algorithms (control by hydraulic signal and control by non-hydraulic signal) were implemented in MaizeSim. Corn plants were grown in sunlit growth chambers and irrigated with different amounts of water. Simulated transpiration and photosynthesis rates were compared with those measured from the chambers. Results indicated that the coupled model was able to simulate the changes in transpiration and photosynthesis rate of corn plants under drought stress accurately. When simulating corn transpiration under drought stress, the algorithm with hydraulic signal performed better than the algorithms with non-hydraulic and no signals. Reasons for these differences were discussed. It was also found that the simulated photosynthesis rate was not as sensitive to stomatal closure as the simulated transpiration. The result agreed with the differences in sensitivity of photosynthesis and transpiration to changes in stomatal closure that have been reported in the literature. These results suggest that the coupled model not only is a valuable tool in studying corn transpiration and photosynthesis under drought stress, but it also provides a platform to implement and evaluate algorithms in studies on corn crop water dynamics and CO2 assimilation.