Figure 2.

Illustration of leaf-level responses of CO₂ assimilation rate to intercellular CO₂ (C_i) with diurnal variation in temperature and irradiance, which both peak at midday. CO₂ assimilation rate is Rubisco limited at low C_i (red lines), and RuBP regeneration is limited at high C_i (blue lines). A hypothetical diurnal path of leaf CO₂ assimilation rate and the corresponding C_i are shown in black. The impact of changing Rubisco or RuBP regeneration capacity depends on irradiance, temperature, stomatal conductance, and leaf orientation.