Effect of NaCl stress and Ca~(2+) regulation on ion distribution in root tissues of Cyclocarya paliurus seedling

The ion concentration and distribution in root tissues of Cyclocarya paliurus(Batal.) Iljinskaja seedlings under NaCl stress and Ca2+ regulation were studied by X-ray microanalysis technique.The results showed that under 3.0 and 5.0 g·L-1 NaCl stress,relative contents of Na+ and Cl-in different tissues of root increased,and that of K+,Ca2+ and Mg2+ decreased.After treated by 5.0 g·L-1 NaCl stress and 3.0 g·L-1 Ca(NO3)2,relative content of Na+ reduced and that of K+ increased,and the variation of Cl-relative content was very slightly.With increasing of NaCl concentration,Cl-relative contents in stele and cortex increased,most of Na+ aggregated to cortex and epidermis.Ratio of K+ transporting from cortex into stele increased,while ratio of Ca2+ from epidermis into cortex decreased and from cortex into stele increased.Under 5.0 g·L-1 NaCl stress with high concentration of Ca(NO3)2,the variation of Cl-distribution ratio was not evident,Na+ transporting from epidermis to cortex increased whereas reduced from cortex into stele,and variation of K+ and Ca2+ distribution ratio was not apparent.It is concluded that high concentration of NaCl stress disruptes ion balance in root of C.paliurus seedlings and regulation effect of exogenous calcium(1.0-3.0 g·L-1) is not significant.