In conclusion, elevated [CO2] alleviated the adverse effects ofhigh NaCl (90 mM) through greater stomatal closure and reductionof the transpiration rate, which may have allowed the plants tomaintain their water balance under salt stress through increasedhydraulic conductance. PIP aquaporins abundance in the rootsseems not to contribute to this enhanced L0although the effectof CO2on aquaporins functionality must not be discarded. Also,at 90 mM NaCl and elevated [CO2], a minimal water loss and anenhanced CO2assimilation is represented as the highest WUE, andthe increased abundance of PIPs in the leaves must be consideredas they may influence the CO2assimilation as well as the leaf cellwater permeability. The dual functions of aquaporins in leaves androots reveal that their contribution to water flow may be relativelycomplex and highly regulated. Also, lesser reductions of bysalinity were found under elevated [CO2], compared to ambient[CO2]. However, no differences in were observed in the salinisedbroccoli plants, when both CO2levels were compared, with theresult that the greater net carbon assimilation rates under elevated[CO2] did not necessarily produce higher solute concentrations.In fact, whereas 90 mM NaCl reduced the rate of photosynthe-sis (A) and the biomass with regard to control, at ambient [CO2],they were maintained under the combination of high NaCl andenhanced [CO2]. Therefore, under elevated CO2and non-stressfulconditions the tightly control of root hydraulic conductance maybe related to the content of PIPs confirmed the first premise of ourhypothesis. However, under high salt stress, a direct influence ofaquaporin abundance at elevated CO2may not be related with theroot hydraulic conductance. But, the increased abundance of PIPsin the leaves may influence not only the CO2assimilation but also