Improving the cotton simulation model, GOSSYM, for soil, photosynthesis, and transpiration processes

Area of Science:

• Agricultural Science
• Crop Modeling
• Plant Physiology

Background:

• The GOSSYM model simulates cotton growth, incorporating a 2D soil model (Rhizos) and an empirical photosynthesis function.
• Existing GOSSYM limitations include water movement based on water content gradients and an empirical photosynthesis response to elevated CO2.

Purpose of the Study:

• To improve the GOSSYM cotton crop simulation model by enhancing its soil, photosynthesis, and transpiration components.
• To evaluate the performance of the modified GOSSYM model using field data.

Main Methods:

• Replaced the Rhizos soil model with the mechanistic 2DSOIL finite element model.
• Implemented the Farquhar biochemical model for photosynthesis and the Ball-Berry model for transpiration.
• Validated the modified GOSSYM against data from soil-plant-atmosphere-research (SPAR) chambers.

Main Results:

• Modified GOSSYM showed improved predictions for net photosynthesis (RMSE 25.5 vs. 45.2 g CO2 m-2 day-1) and transpiration (RMSE 3.3 vs. 13.7 L m-2 day-1).
• The enhanced model achieved a higher index of agreement for both photosynthesis (0.89 vs. 0.76) and transpiration (0.92 vs. 0.14).
• Crop yield prediction accuracy was improved by 6.0% with the modified GOSSYM.

Conclusions:

• The integration of 2DSOIL, Farquhar, and Ball-Berry models significantly enhances GOSSYM's simulation of soil, photosynthesis, and transpiration.
• Modified GOSSYM exhibits improved predictive capabilities for cotton crop growth, development, and yield.