Positive effects of NaCl on the photoreaction and carbon assimilation efficiency in Suaeda salsa

Suaeda salsa L. is a typical euhalophyte and can be used as a model halophyte for research on salt tolerance. S. salsa seedlings were cultured with 0, 200 and 500 mM NaCl for 2 and 14 days. The results revealed that 200 mM NaCl promoted the shoot dry weight, net photosynthetic rate (Pn), chlorophyll content, electron transfer rate, NADPH level, activities of ferredoxin-NADP oxidoreductase, ribulose-1, 5-bisphosphate carboxylase (Rubisco) and Rubisco activase, particularly the Rubisco activity, chlorophyll content and Pn, when the seedlings were treated with 200 mM NaCl for 14 days. Moreover, 500 mM NaCl had no adverse effects on those parameters. In conclusion, NaCl improved the photoreaction and carbon assimilation efficiency of S. salsa. The increased Rubisco activity and chlorophyll content may play critical roles in the enhancement of the photosynthetic efficiency in S. salsa under saline conditions, which may explain why S. salsa can produce the highest biomass at approximately 200 mM NaCl.