Effects of NaCl Stress on the Inorganic Ion Contents in Atriplex undulata Roots and Leaves

Atriplex undulata were treated with different concentrations of NaCl solutions. The results were as follows: The biomass of shoots and roots was enhanced by the treatment of 100 mmol/L NaCl solutions., but it was inhibi- ted by higher NaCl concentrations.The Na⁺ and Cl^- contents of different parts increased evidently with increasing NaCl concentrations; those in leaves higher than those in roots, and those in young leaves higher than those in old leaves under NaCl treatments. No significant changes in the contents of K⁺ in leaves (except old leaves treated with 500 mmol/L NaCl) and K⁺, Ca ²⁺ and NO₃^- in roots were found. Na/Kratios in leaves increased with increasing NaCl concentrations under lower salt concentrations (0～300 mmol/L NaCl) , but they decreased ( in old leaves) or remained relatively stable ( in young leaves ) under higher salt concentrations (400～500 mmol/L NaCl). The selectivity of K⁺ over Na⁺ and the ability of osmotic adjustment dramatically increased while osmotic potential decreased with increasing NaCl concentrations. Furthermore, the characterized adaptability to diffrent salt environments of Atriplex undulata was discussed.