Measuring Photorespiration with the LI-6400/XT System
Introduction
Oxygen is a competitive substrate for ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), resulting in an inhibitory effect on net photosynthesis. Higher CO2 to O2 ratios inside the leaf decrease the Rubisco-catalyzed reactions with O2, resulting in less carbon-wasteful reactions in the light (photorespiration). Photorespiration increases on hot, dry days when evaporative stress can cause stomata to close, lowering the intercellular CO2:O2 as CO2 is assimilated. When Rubisco was evolved by plants, earth’s atmosphere had much higher concentrations of CO2 and relatively…