MODELING OF LIGHT-DRIVEN RUBP REGENERATION, CARBOXYLATION AND CO2 DIFFUSION FOR LEAF PHOTOSYNTHESIS

A two-stage model proposed by Thornley on the photosynthetic rate in l eaves is modified to include the transport processes of CO2 molecules. The model assumes the Rubisco-catalysed consumption of CO2 and the li ght-driven regeneration of 3-PGA producing sugar. The novel feature is the detailed analytical analysis of stationary CO2 diffusion in the m esophyll along with respiration. The model is tested against laborator y measurements of CO2 exchange rates of single birch leaves and empiri cal constants entered into the model are assessed by means of the data . To yield a realistic reaction rate constant for carboxylation, the m odel requires that the diffusion coefficient describing mesophyllic tr ansport must be somewhat larger than CO2 diffusivity in pure liquid wa ter. (C) 1997 Academic Press Limited.