ARS | Publication request: SIMULATION OF POTATO CANOPY GROWTH AND GAS EXCHANGE

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2006
Publication Date: March 20, 2006
Citation: Fleisher, D.H., Kim, S., Timlin, D.J., Yang, Y., Reddy, V. 2006. Simulation of potato canopy growth and gas exchange [abstract]. Biological Systems Simulation Conference. p.42.

Technical Abstract: Potato models, such as SIMPOTATO, typically use a 'big leaf' approach to simulate increases in canopy leaf area. Daily plant growth is simulated by multiplying the quantity of radiation intercepted in the plant canopy by an empirical constant, radiation use efficiency (RUE). Additional empirical relationships between the environment and plant nutritional status are used to modify the amount of predicted canopy growth. A new model, SPUDSIM, was developed in order to improve the level of detail and accuracy in SIMPOTATO by focusing at the individual leaf level. SPUDSIM includes new components for individual leaf appearance, leaf expansion, and branch formation. Coupled models for leaf level photosynthesis, stomatal conductance, and energy balance (Kim and Lieth, 2003) replace the RUE based growth routine used in SIMPOTATO. A radiative transfer routine that estimates intercepted photosynthetically active radiation for sunlit and shaded leaves was also added to the model. SPUDSIM can be operated at various time increments to simulate potato growth and phenology. During each time increment, net photosynthetic rate is estimated for sunlit and shaded leaf area. Photosynthate is partitioned among leaves in the canopy according to leaf location, size, potential expansion, and plant assimilate status. Assimilate allocation to branches, roots, and tubers proceeds according to fixed partitioning coefficients defined in SIMPOTATO. Remaining photosynthate is used to support the appearance of new leaves or branches in the canopy according to predicted demand. Data from SPAR (soil-plant-atmosphere research) chamber experiments conducted in 2004 and 2005 at USDA-ARS Beltsville, MD were used to evaluate SPUDSIM predictions. The data includes time-series measurements of whole plant gas exchange and canopy architecture (e.g. leaf number, lateral branch numbers, etc.) at different growth temperatures and atmospheric carbon dioxide concentrations. Results indicate that SPUDSIM accurately simulates individual leaf growth and whole plant gas exchange in potato canopies.