Nutrient status in rhizosphere microzone of Fraxinus americana under salt stress

The objectives of this research are to study nutrient absorption, accumulation and deficit in the root-soil interface of Fraxinus americana, and to provide the basis for plant salt-tolerance mechanism and solonchak improvement and utilization. X-ray electron probe was used to study the effect of salt stress on the distribution and relative content of nutrient elements in the rhizosphere and root tissue. The results indicate that contents of Ca, Mg, and Cl in roots of Fraxinus americana are high at the low concentration of salinity (3 g/L) compared to the control (0 g/L), whereas at the high concentration of salinity (9 g/L) contents of Ca, Mg, and Cl in roots are low. Meanwhile, contents of Na, K, and Fe in roots and Na in the rhizosphere are increased with increasing levels of salinity. Consequently, the structure of plasma membrane in the cell is damaged by over-accumulation of Na in roots of Fraxinus americana and then indequate nutrition resulting from nutrition loss is induced, leading to salt injury. Therefore, the study implies that absorption and accumulation of Na might be main mechanism of generating salt injury.