Abstract: Salinity is among the important ecological factors affecting the distribution of Spartina alterniflora in coastal wetland. In this study, we cultivated S.alterniflora in fresh water, and collected the seeds. Then the germination and embryo growth of the seeds in different NaCl salt solutions(salinity between 0~90 g·L^-1) were observed. It indicated that S.alterniflora cultivated with fresh water could germinate and the maximum germination rate was 69%; salt stress decreased seed initial germination rate, seed germination velocity and embryo growth; in high salt solution (salinity ＞30 g·L^-1), seed initial germination rate decreased and the seed germinated embryo without radicle; after the stressed embryo was transplanted into fresh water, adventitious root of the embryo grew out in basal part of the coleoptile, but the radicle could not grow out; seed dormancy happened in high salinity, and when salt stress was relieved, the seed germination rate partially recovered; there was a significant positive correlation between the recovered seed germination rate and the salt stress it suffered before; the relationship between the total germination rate and the solution salinity was a secondary function; the seed in the solution of 63 g·L^-1 NaCl showed the lowest germination rate. The special strategies of seed germination and embryo growth under salt stress were probably an important reason for S.alterniflora to cope with and successfully invade the coastal wetland.

Key words: Spartina alterniflora, salt stress, seed germination, embryo growth