Water relations are of special importance since water is consid-ered the primary factor limiting growth and productivity (Schulzeet al., 1987). High [CO2] in the atmosphere allowed plants cultivatedin saline conditions to increase their water use efficiency (WUE) andwater potential, in order to avoid salinity damage (Geissler et al.,2009a). In addition, elevated CO2improves plant tolerance of salin-ity by increasing the carbon assimilation rate (Rozema et al., 1991)and enhancing the synthesis and activity of enzymes and proteins,which confers on the plants an energy gain that is used mainlyfor more-efficient detoxification of reactive oxygen species and iontransport/compartmentation (Geissler et al., 2009b, 2010).