Effect of potassium on uptake and translocation of sodium and potassium in Chinese cabbage under NaCl stress

To investigate the influence of potassium (K+) on the salinity tolerance of Chinese cabbage (Brassica pekinensis Rupr.) seedlings, the plants were cultured at three K+ levels (0, 5, or 10 mM), under normal (0 mM NaCl) and high-salt (100 mM NaCl) conditions. The results indicated that the dry weight of Chinese cabbage increased with the application of K+ under salt stress. Addition of K+ increased K+ concentrations and suppressed sodium (Na+) concentration, which eventually increased the K+/Na+ ratios in roots or shoots. Application of K+ enhanced the uptake of K+ and suppressed the uptake of Na+. Moreover, the ratios of shoot-K+/root-K+ increased considerably, but the ratios of shoot-Na+/root-Na+ decreased in response to K+ application. It was concluded that the application of K+ could enhance the salt stress tolerance in Chinese cabbage because more K+ than Na+ was absorbed and translocated from roots to shoots.