摘要

High Na stress induces deleterious effects on plants by ion toxicity, inadequate water status and nutrient imbalances. Exogenous Ca ions that can sustain a high absorption rate of both Ca and K against Na in plants improve plant growth. To examine the effect of adequate internal water status on the process of cation absorption, water spray treatments were compared with Ca addition treatments at high (40, 80 and 120 mol m(-1)) NaCl concentrations. The water spray treatments improved internal water status and led to a higher Ca accumulation (73.2-85.2% increase) in the shoots than Na treatments at the same external Na and Ca concentrations. Higher Ca contents of shoots in the water spray treatments than in the corresponding Na treatments were induced by the higher transpiration stream concentration factor of Ca. Examination of plants with an adequate water status in shoots revealed that the active absorption of Ca was sensitive to the internal water status, and that there was no antagonistic effect of Na on Ca. It was necessary for the NaCl-salinized plants that Ca be actively absorbed and transported to avoid salinity damage, which was achieved through adequate water status.