Responses of Photosynthesis and Dark Respiration to Temperature

This analysis suggests that a model of the temperature dependence of carbon exchange by a plant can be developed based upon absolute reaction rate theory. Component temperature-dependent physiological processes necessary to describe net photosynthesis over the biological temperature range include the light reaction, dark reaction (carboxylase CO2 uptake, oxygenase photorespiration) and mitochondrial dark respiration. An essential assumption of the model is the reversibility of thermal inhibition. Supporting evidence for this assumption is provided within the biological range. Thermodynamic constants were found to be strongly correlated with the thermal environment to which they were adapted. There was little difference in non-photorespiration thermodynamic constants between C2 andC4species within thermal habitat types. The model shows the observed shift in temperature optima with light intensity as a natural consequence of enzyme kinetics and absolute reaction rate theory.