Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 19, 1998
Publication Date: N/A
Crop simulation models used in climate change studies should be capable of reproducing changes in growth response to Ca with changes in environmental conditions. Changes with soil water status in crop growth response to Ca can be simulated if stomatal resistance in the model varies directly with air-leaf Ca gradient, inversely with leaf carboxylation rate, and exponentially with leaf turgor. Resistance then increases with Ca relatively less, and CO2 fixation increases with Ca relatively more, under water-limited vs. non-limited conditions. As part of the ecosystem model ecosys, this simulation technique caused changes in leaf conductance, CO2 fixation, water potential, temperature and energy balance that were within the SE of changes measured under 355 vs. 550ppm Ca and low vs. high irrigation in a Free-Air CO2 Enrichment (FACE) experiment on wheat. Changes with Ca in simulated crop water relations allowed the model to reproduce a measured increase of 20% vs. 10% in seasonal wheat biomass and a measured decrease of 2% vs. 5% in seasonal evapotranspiration under 550ppm Ca and low vs. high irrigation. The basic nature of the processes simulated in this model is intended to allow its use under a wide range of soil, management, and climate conditions.