signal that links stomatal aperture to mesophyll demand for CO2
which generally declines under elevated CO2. Decrease in Cs along
with increase in Ci are the common responses in plants exposed to
high CO2 (Booker and Fiscus, 2005) and was also observed in this
study (Fig. 1). A decrease in Cs resulted in a decrease in E and an
increase in WUE under ECO2 + AO3 and ECO2 + EO3 compared to
ACO2 + AO3. Higher WUE was associated with a decrease in E alongwith an increase in Ps under elevated CO2 (Kyei-Boahen et al.,
2003); however, in the present study, an increase in WUE was
mainly due to an increase in Ps rate.