Modeling Diurnal Photosynthesis
Modeling Diurnal Photosynthesis
This Demonstration simulates the response of net photosynthetic carbon assimilation () over the diurnal time course for either a sunny or overcast day. The equations are based on the leaf model of photosynthesis [1] that predicts based on the most limiting of three processes: (1) the kinetics of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (or rubisco) for fixing , (2) the rate of RuBP regeneration associated with electron transport rates on the thylakoid membrane (RuBP), and (3) the rate at which inorganic phosphate, required for regenerating ATP from ADP, is released during the utilization of triose phosphate (TPU). The most limiting process will determine the rate of ; the process limiting, rubisco, RuBP, or TPU is indicated by the color of the line. Adjusting any of the parameters will influence the pattern of throughout the day; two modeled lines, a solid (left controls) and a dashed (right controls), are included to allow for direct comparison to parameter adjustments. The equations from the original model [1] have been corrected with the temperature functions from [2] for rubisco-limited photosynthesis, [3, 4, 5] for RuBP-limited photosynthesis, and [6] for TPU-limited photosynthesis. Changes in the stomatal aperture in response to environmental factors, which influences , are not simulated here.
A
µmol
-2
m
-1
s
A
CO
2
A
A
A