Abstract: Salt stress inhibits plant growth, and its damage to plants differs with salt concentration. In this paper, a pot experiment was conducted to study the eco-physiological adaptability of Suaeda heteroptera Kitagawa under different salt conditions. The results showed that the inhibitory effect of salt on the growth of S. heteroptera seedlings increased with increasing salt concentration. Under low salinity stress, the fresh and dry weights and the water content of shoots and roots had no significant difference with the control; but under high salinity stress, the seedling growth was seriously affected, with more inhibition on shoots than on roots. When the NaCl concentration was lower than 200 mmol·L^-1, there was a positive correlation between the free praline, soluble sugar, and protein contents in shoots and the salinity; when the NaCl concentration was higher than 300 mmol·L^-1, there was a negative correlation between osmosis-regulating substance concentration and salinity.

Key words: Outer Changjiang estuary, Red tide, Plume front, Changjiang River diluted water, Upwelling