Interactions of Elevated CO2 Concentration and Drought Stress on Photosynthesis in Eucalyptus Cladocalyx F. Muell

Response of net photosynthetic rate (P N), stomatal conductance (g s), intercellular CO2 concentration (c i), and photosynthetic efficiency (Fv/Fm) of photosystem 2 (PS2) was assessed in Eucalyptus cladocalyx grown for long duration at 800 (C800) or 380 (C380) µmol mol-1 CO2 concentration under sufficient water supply or under water stress. The well-watered plants at C800 showed a 2.2 fold enhancement of P N without any change in g s. Under both C800 and C380, water stress decreased P N and g s significantly without any substantial reduction of c i, suggesting that both stomatal and non-stomatal factors regulated P N. However, the photosynthetic efficiency of PS2 was not altered.