Physiology And Ecology. Elaeagnus Angustifolia Under Salt Stress Response And Ion Allocation Study

The growth indices, biomass distribution, photosynthesis and transpiration parameters, osmotic regulation in leaf, and inorganic ions content in different organs of Elaeagnus angustifolia L. under different levels of salt stress were determined, and its ecophysiological adaptability and ions distribution traits were gotten in controlled experiments, which provided effective evidence for its application in garden construction. The primary results were as follows:(1) The relative growth rate (RGR) and biomass of E. angustifolia declined and the growth of height, leaf number and leaf area were inhibited under salt stress, and the inhibition degree depended on stress level and stress time. The inhibition effect of salt stress to RGR and biomass in different organs presented in the sequence of leaf＞stem＞root, which resulted in the increasing root-shoot ratio.(2) The net photosynthesis rate (Pn) of E. angustifolia declined under salt stress. The depressed stomatal conductance and photochemical activity of PSⅡare the main factors responsible for the declined Pn, while the reduced leaf chlorophyll content played a less important role among these factors.(3) The fluorescence parameters of dark-adapted leaves went through stress phase and recovery phase, while the fluorescence parameters of light-adapted leaves and Pn went through stress phase, regulation phase and secondary stress phase. Both recovery phase and regulatory phase illuminated salt adaptability of E. angustifolia. And the secondary stress phase illuminated the depressed physiology function of E. angustifolia, but they still could kept alive.(4) The osmotic regulation in leaf of E. angustifolia was achieved through the increasing free proline and K⁺ content in the early salt stress days, and through the increasing Cl^- and Na⁺ and maintaining of high level of proline under long-term salt stress. And the water use efficiency (WUE) was highten under long-term salt stress.(5) E. angustifolia accumulated lots of Cl^- and Na⁺ under long-term salt stress, and its leaf and root accumulated more Cl^- and Na⁺ than main stem and lateral branch did. It can be concluded that E. angustifolia is a salt tolerance halophyte. The contents of K⁺, Ca²⁺ and Mg²⁺ decreased under long-term salt stress, and their widest decreasing range occurred to lateral branch, thin root and leaf, respectively. The selective transportation ability for K⁺, Ca²⁺ and Mg²⁺ strengthened in the processes of thin root to thick root and thick root to main stem, thus more K⁺, Ca²⁺ and Mg²⁺ were transported to shoot and more Na⁺ was kept in root.