A model for photosynthesis and photorespiration in C₃ plants based on the biochemistry and stoichiometry of the pathways

Abstract

Abstract. A model is developed for photosynthesis and photorespiration in C3 plants, using an equation for the multisubslrate ordered reaction of ribulose 1,5‐bisphosphalc carboxylase‐oxygenase (Farazdaghi & Edwards, 1988). The model examines net CO2 fixation with O2 inhibition, and mutual inhibition when equilibrium exists between carboxylation and oxygenation (at the CO2 compensation point). It is based on the stoichiometry of energy requirements and O2, and CO2 exchange in the cycles, the quantum efficiency for RuBP generation, the maximum capacity for RuBP generation, the carboxylation efficiency with respect to [CO2], and the oxygenation efficiency with respect to [O2]. With increasing concentrations of CO2 above the CO2 compensation point, decreasing quantum flux density, or decreasing O2, simulations show that the rate of photorespiration progressively decreases. The two components of O2 inhibition of photosynthesis change disproportionately with increasing CO2 concentration. According to the model, the energy utilized during photosynthesis at the CO2 compensation point is about half that under atmospheric conditions.

A mechanistic model for the photosynthesis–light response based on the photosynthetic electron transport of photosystem II in C3 and C4 species

“…Models of photosynthesis of varying complexity have been used to predict photosynthesis to highlight processes and pathways that are not well understood (Farazdaghi & Edwards, 1988). A number of mechanistic and empirical models have been developed for photosynthesis in C 3 plants; however, the most frequently used for understanding the photosynthetic response to CO 2 is the biochemical model of Farquhar et al (1980), or its various refined forms (e.g.…”