Abstract: This work is aimed to explore the effects of salt stress on seed germination,growth and physiological and biochemical indexes of Reaumuria soongorica,and to provide data support for the analysis of salt tolerance mechanism and further relevant research. The seeds of halophytes R. soongorica were used as experimental materials and NaCl solution was for simulating salt stress,the germination of R. soongorica seeds,changing trend of root length,seedling height and physiological and biochemical indexes after germination were investigated under the treatment of different concentrations of NaCl（0,50,100,150,200,300 and 400 mmol/L）.The results showed that：（1）Compared with the control,the germination rate of R. soongorica treated with 50 mmol/L increased,the root length and plant height increased significantly. With the increase of concentration,the germination time of R. soongorica delayed,the germination rate decreased,the salt damage rate increased,and the root length and plant height decreased significantly. When the salt concentration increased to 400 mmol/L,the R. soongorica did not germinate,but still remained the germination vigor. The relative germination rate of seeds after 35 d of 400 mmol/L stress was 105.43% by re-geminating treatment. （2）With the increase of NaCl concentration,the contents of malondialdehyde（MDA）and proline（Pro）in R. soongorica increased significantly,and the activities of peroxidase（POD）and superoxide dismutase（SOD）increased in varying degrees. （3）Using the relative germination rate and the plant length decreased to 50% of those in the control as a standard,the germination salt tolerance threshold was 273 mmol/L and the optimal salt concentration was 45.78 mmol/L,and the growth salt tolerance threshold was 388.19 mmol/L and optimal one was 50.59 mmol/L respectively. R. soongorica remained germination vigor for a long time under the stress environment,and concentrated a large number of germination quickly when the germination conditions were suitable. The growth threshold concentration of R. soongorica was higher than the germination threshold concentration,indicating that the germination period was the key period for it to complete its life cycle under salt stress. With the increase of salt concentration,the growth of R. soongorica was inhibited to varying degrees,the plants scavenged MDA by increasing POD and SOD activities and thus increased Pro content in a certain degree of stress to maintain the normal physiological metabolism.

Key words: Reaumuria soongorica, NaCl stress, indicators of growth, physiological and biochemical indexes, salt tolerance threshold, germination stage, salt tolerance evaluation