ARS | Publication request: MODELING CANOPY DEVELOPMENT AND PHOTOSYNTHESIS IN POTATO

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract
Publication Acceptance Date: November 12, 2003
Publication Date: November 12, 2003
Citation: Timlin, D.J., Kim, S., Pachepsky, Y.A., Reddy, V., Fleisher, D.H., Fraisse, C., Alva, A.K., Baker, J.T. 2003. Modeling canopy development and photosynthesis in potato [abstract]. American Society of Agronomy Meetings. CDROM.

Technical Abstract: Our goal is to develop a mechanistic simulator of potato growth and development that is coupled with comprehensive two dimensional models of soil and atmospheric processes. In order to simulate photosynthesis on a more mechanistic level, we used a coupled, leaf level model of photosynthesis, stomatal conductance, and transpiration (Kim, 2001). This allows a coupling of the supply function of diffusion of CO2 through the stomata (as controlled by stomatal resistance) to the demand function of the CO2 fixation reaction. Recent advances in gas-exchange systems greatly simplify the parameterization of the model. The model was parameterized using data from leaf level photosynthesis measurements. Contributions of various parts of the canopy to light interception and photosynthesis were evaluated by removing sections of the canopy and comparing canopy level photosynthesis before and after leaf removal. Canopy level photosynthesis measurements from the Alternate Crops and Systems Laboratory's Soil Plant Atmosphere Research (SPAR) chambers were used to evaluate the performance of the photosynthesis model. Simulated photosynthesis values did follow the measured data at the extremes of the temperature ranges. Light interception was more sensitive to structural components of the canopy such as branch or secondary branch number rather than leaf area. However, uncertainties in leaf age and canopy light interception were sources of error.