Fig. 4.

Modelling the response of C₄ photosynthesis to intercellular [CO₂], C_i, using the C₄ photosynthesis model developed by von Caemmerer (2000). (A) CO₂ assimilation rates (A, continuous line) and photorespiration (PR, dotted line); (B) the ratio of the rates of electron transport to CO₂ assimilation (J/A, continuous line) and leakiness (Φ, dotted line); and (C) bundle sheath [CO₂] ([CO₂]_BS, continuous line) and [O₂] ([O₂]_BS, dotted line). The modelling simulates a mature C₄ leaf with maximal PEPC and Rubisco activities of 120 and 40 µmol m^–2 s^–1, respectively; a bundle sheath conductance to CO₂ per leaf area of 3 mmol m^–2 s^–1. Other parameters are similar to those described in table 2 of von Caemmerer and Furbank (1999). The shaded area represents the likely range of C_i experienced by well-watered and mildly water-stressed C₄ leaves.