The present study aimed to determine the mechanism of cation-selective secretion by multicellular salt glands.Using a hydroponic culture system,the secretion and accumulation of Na+ and K+ in Tamarix ramosissima and T.laxa under different salt stresses (NaCl,KCl and NaCl+KCl) were studied.Additionally,the effects of salt gland inhibitors (orthovanadate,Ba2+,ouabain,tetraethylammonium (TEA) and verapamil) on Na+ and K+ secretion and accumulation were examined.Treatment with NaCl (at 0-200 mmol L 1 levels) significantly increased Na+ secretion,whereas KCl treatment (at 0-200 mmol L 1 levels) significantly increased K+ secretion.The ratio of secretion to accumulation of Na+ was higher than that of K+.The changes in Na+ and K+ secretion differed after adding different ions into the single-salt solutions.Addition of NaCl to the KCl solution (at 100 mmol L 1 level,respectively) led to a significant decrease in K+ secretion rate,whereas addition of KCl to the NaCl solution (at 100 mmol L 1 level,respectively) had little impact on the Na+ secretion rate.These results indicated that Na+ secretion in Tamarix was highly selective.In addition,Na+ secretion was significantly inhibited by orthovanadate,ouabain,TEA and verapamil,and K+ secretion was significantly inhibited by ouabain,TEA and verapamil.The different impacts of orthovanadate on Na+ and K+ secretion might be the primary cause for the different Na+ and K+ secretion abilities of multicellular salt glands in Tamarix. The present study aimed to determine the mechanism of cation-selective secretion by multicellular salt glands. Using a hydroponic culture system, the secretion and accumulation of Na + and K + in Tamarix ramosissima and T. laxa under different salt stresses (NaCl, KCl and NaCl + KCl) were studied. Additionally, the effects of salt gland inhibitors (orthovanadate, Ba2 +, ouabain, tetraethylammonium (TEA) and verapamil) on Na + and K + secretion and accumulation were monitored. Treatment with NaCl significantly increased Na + secretion, KCl treatment (at 0-200 mmol L 1 levels) significantly increased K + secretion. The ratio of secretion to accumulation of Na + was higher than that of K +. The changes in Na + and K + secretion differed after adding different ions into the single-salt solutions. Addition of NaCl to the KCl solution (at 100 mmol L 1 level, respectively) led to a significant decrease in K + secretion rate, an addition of KCl to the NaCl solution (at 100 mmol L 1 le vel, respectively) had little impact on the Na + secretion rate.These results indicate that Na + secretion in Tamarix was highly selective. In addition, Na + secretion was significantly inhibited by orthovanadate, ouabain, TEA and verapamil, and K + secretion was significantly inhibited by ouabain , TEA and verapamil. The different impacts of orthovanadate on Na + and K + secretion might be the primary cause for the different Na + and K + secretion abilities of multicellular salt glands in Tamarix.