Abstract:Salt-dilution halophyte Suaeda salsa, salt-secretory halophytes Atriplex centrMasiatica and Limonium bicolor were treated with different concentrations of KC1 and isosmotic NaC1. It was found that the organic dry weight and net photosynthetic rate of these plants were inhibited by 100--500 and 100--400 mmol/L KC1 respectively, indicating the existance of a relationship between the growth inhibition by K+ and the decrease of photosynthesis in halophytes. After treatment with 100--400 mmol/L KCI, the content of K+ increased while that of Na+ decreased, but there were no change in osmotic potential and ability of osmotic adjustment. It proved that growth inhibition by K+ was related to Na+ deficiency in osmotic adjustment and the toxic effect of high K+ on cells. Further there was no direct relation between the decrease of growth and photosynthesys and the content of sugars in leaves. Moreover, the inhibition of ATPase activity by high K+ concentration was probably related to growth inhibition.