Study On Characters And Assessments Of Salt Tolerance In The Seedlings Of Several Introductory Tree Species

In greenhouse, four-month-old seedlings of eleven tree species grown in pots containing soils were subjected to salinity (NaCl) treatments. They were Syringa murensis japonica, Pyrus calleryana Decne., Ptelea trifoliata L., Shepherdia argentea (Pursh) Nutt., Viburnum opulus L., Cytisus scoparius Link., Betula lenta L., Rhus glabra L., Spartium junceum L., Rhus trilobata Nutt., and Laburnum×watereri"vossii". Salt stress levels were 0, 3‰, 5‰, 8‰and 10‰of soil dry weight. After five weeks of treatment, height growth, the biomass, root/shoot ratio, the morphological changes after adding salt, membrane permeability, chlorophyll content, free proline content, soluble sugar content, MDA content, and the concentration of K+ and Na+ content in roots, stems, and leaves of seedlings were determined. The results obtained by the experiment were as follows: (1) With the increasing of salinity concentration, the morphological changes of the different tree species after adding salt were different , the biomass decreased gradually(Compared with the control, the biomass of Rhus trilobata L., Betula lenta L., Ptelea trifoliata L., Spartium junceum L. and Cytisus scoparius Link. decreased 59.70%,50.33%,39.20%,23.78% and 19.36% respectively under the 5‰salt stress.) , and high salt content and/or long period of treatment caused the height growth decreased accordingly; (2) With the increasing of salinity concentration, proline content, Na+ concentration and membrane permeability all rose significantly, whereas chlorophyll content and K+/Na+ ratio dropped; (3)There were no remarkable differences concerning K+, MDA content among the tree species studied; (4) Under the salt stress, soluble sugar content took on different changes because of different tree species; (5) Subordinate function value method was adopted in this paper to evaluate salt resistance of the tree species for the experiments comprehensively. The results of comprehensive evaluation by means of the subordinate degree comprehensive value of growth and physiological characters showed that the salt resistance sequence of the eleven tree species studied was: Syringa murensis japonica > Pyrus calleryana Decne. > Shepherdia argentea (Pursh) Nutt.> Rhus trilobata Nutt. > Ptelea trifoliata L.> Laburnum×watereri"vossii" > Cytisus scoparius Link. > Viburnum opulus L.> Spartium junceum L. > Betula lenta L. > Rhus glabra L..