Abstract: 【Objective】 The objective of this paper is to investigate the relationship between the salt-tolerance and the microdistribution of mineral ions in roots, stems and leaves of Distichlis spicata and Festuca arundinacea under salt stress. 【Method】 Distichlis spicata (halophyte) and Festuca arundinacea (glycophyte) were grown hydroponically with 250mM NaCl. Root tips, stems, and leaves were harvested for microanalysis 20 days after transplanting. Using an energy dispersive X-ray microanalyzer (EDX), the X-ray percentage of atom content and the peak of X-ray energy spectra intensity were measured. 【Result】It was shown that high Cl- and Na+ X-ray peaks were recorded in root tissues regardless of D. spicatar and F. arundinacea, but X-ray percentages of Na+ and Cl- content in root stelar cells of F. arundinacea were higher than in D. spicata. While comparable, the higher percentage of Na+ content existed in the stem xylem, and higher percentage of Cl- content distributed in the stem phloem in D. spicata than in F. arundinacea. The concentration of Na+ in leaves of F. arundinacea was 2 times more than in leaves of D. spicata【Conclusion】 Distichlis spicata regulated toxic ion absorption by the mechanism of selective absorption in roots, and recirculated Na+ back to roots by phloem or retrieval Na+ from xylem. Thus less toxic ion was transported to leaf tissue. Therefore the microdistribution of mineral ions in plants was involved in salt tolerance.

Key words: Distichlis spicata , Festuca arundinacea, salt stress, salt-tolerance, mineral ions, microdistribution, X-ray energy spectrum