Study On The Physiological And Biochemical Characteristics Of Zelkova Schneideriana Under The NaCl Stress

The seed germination indices of Rugao provenance and physiological characteristics of 1a seedlings of Zelkova schneideriana under NaCl stress were analyzed .The results showed as follows:1. The seed germination rate, germination index and vigor index of Rugao provenance of Z.schneideriana decreased dramatically with the increase of NaCl concentrations. The seedling height and root length decreased significantly under NaCl concentrations from 0.4% to 0.8%. The SOD and POD activities of the seedlings of Z.schneideriana were increased earlier and decreased later. The MDA content increased slowly under NaCl concentrations from 0.6% to 0.8%.2. Both with the increase of NaCl concentrations higher than 0.15% and with the prolong of stress time, the cell membrane permeability, MDA and proline contents of leaves of the 1a seedlings of Z.schneideriana increased significantly. The SOD and POD activities of 1a seedlings were increased earlier and decreased later. The soluble proteins increased slightly compared with CK under NaCl concentrations of 0.15% and 0.3%, then decreased gradually with the increase of NaCl concentrations higher than 0.3%. The results of SDS-PAGE electrophoresis showed that there is a change of the content of a protein with 57.8KD.3. The chlorophyll content of 1a seedlings of Z.schneideriana decreased gradually with the increase of NaCl concentrations. The chlorophyll fluorescence parameters of PSII potential activity (Fv/Fo),PSII effective photochemical efficiency (Fv'/Fm'), photochemical quench (qP), acyclic electron transport rate (ETR) and PSII actual photochemical efficiency (ΦPSII) were all increased slightly compared with CK under the 0.15% NaCl concentration following a gradually decrease with the increase of NaCl concentrations. However, the non-photochemical quenching coefficient (NPQ) decreased slightly compared with CK under the 0.15%NaCl concentration following a gradually increased with the increase of NaCl concentrations. 4. After duration of 45 days of NaCl stress, the Na⁺ accumulated in the root and stem of Z.schneideriana which affected selective absorption to K⁺, Ca²⁺ and Mg²⁺ of the stem. However, the contents of K⁺, Ca²⁺, Mg²⁺ maintained a high level in the leaf of Z.schneideriana .The selective transportation from stem to leaf was not affected. The K⁺, Ca²⁺, Mg²⁺ contents increased in the leaf with the treatment from 0.15% to 0.45% NaCl concentration.To conclusion, NaCl stress seriously affect the seed germination of Rugao provenance, but their seedlings can grow normally when treated by NaCl with concentrations no higher than 0.2%. The 1a seedlings of Z.schneideriana may grow normally by self-regulation under 0.15% NaCl concentration.