Fig. 5.

The effect of irradiance on the modelled rate of CO₂ assimilation. (A) Light response of the CO₂ assimilation rate at mesophyll cytosolic CO₂ partial pressures, C_m, indicated in the figure. The C₄ photosynthesis model predicts electron transport limitations at all irradiances at C_m values >150 µbar. At lower C_m, CO₂ assimilation rates are enzyme limited at high irradiance. The model was parameterized at 25 °C with values given in Table 1. (B) CO₂ assimilation rate as a function of intercellular CO₂ at the irradiances indicated. The model was parameterized at 25 °C with values given in Table 1.