Comprehensive Evaluation On Salt Tolerance Of Magnolia Denudata,Magnolia Biondii,and Michelia Chapensis Seedlings

Magnolia denudata,Magnolia biondii,and Michelia chapensis are all spring bloom plants of Magnoliaceae.They are all the ideal landscape trees with excellent ornamental characteristics.In order to explore the effects of NaCl stress on the growth and physiological characteristics of Magnolia denudata,Magnolia biondii,and Michelia chapensis,the changes of morphological and physiological indexes with annual seedlings under 0（the control）,100,200,and 300 mmol·L^-1 NaCl were studied by nutrient solution culture method.The main results are as follows:（1）NaCl stress has some inhibitory effects on the growth of three seedlings.With the increase of NaCl concentration,the biomass of root,stem,leave,shoot and whole plant of three seedlings were decreased.The root-shoot ratio was increased.At the end of NaCl stress stage,all of three seedlings showed salt disease symptoms.Judging from the damage symptom of three seedlings,the salt tolerance of Magnolia denudata is not very good.（2）Under NaCl stress,the relative water content of three seedlings showed a trend of decreasing with the rising of NaCl concentration and the prolongation of stress time.（3）Under NaCl stress,the relative electric conductivity and the malondialdehyde content of three seedlings showed a trend of decreasing with the rising of NaCl concentration and the prolongation of stress time.（4）Under NaCl stress,the chlorophyll content of Magnolia denudata and Magnolia biondii showed a trend of increasing firstly and decreasing later with the rising of NaCl concentration and the prolongation of stress time,and Michelia chapensis showed a trend of decreasing.（5）Under NaCl stress,the soluble sugar content of Magnolia denudata and Michelia chapensis under different NaCl concentration showed a trend of increasing firstly and decreasing later with the prolongation of stress time,and Magnolia biondii showed a trend of increasing with the rising of NaCl concentration and the prolongation of stress time.The soluble protein content of three seedling under different NaCl concentration showed a trend of increasing firstly and decreasing later with the prolongation of stress time.The proline content of Magnolia denudata under different NaCl concentration showed a trend of increasing with the prolongation of stress time,Magnolia biondii showed a trend of increasing firstly and decreasing later with the rising of NaCl concentration and the prolongation of stress time,and Michelia chapensis under different NaCl concentration showed a trend of decreasing firstly and increasing later with the prolongation of stress time.（6）Under NaCl stress,the activity of SOD of three seedlings under different NaCl concentration showed a trend of increasing firstly and decreasing later with the prolongation of stress time.The activity of POD of three seedlings showed a trend of increasing firstly and decreasing later with the rising of NaCl concentration and the prolongation of stress time.（7）After comprehensive evaluating the changes of morphological and physiological indexes of three seedlings under NaCl stress,it can be concluded that the salt resistance ability of three plants from large to small is Magnolia biondii,Magnolia denudata and Michelia chapensis.The result shows that all the three plants can adapt to the short-term and low-concentration salt stress.And the salt tolerance of Magnolia biondii is stronger in the saline environment.