Samples of soil and plants were taken from three plant communities in the sulphate-dominant saline soil of Hexi Corridor,
China. The ion(K,Na and Cl) contents of the samples were analysed to investigate
ion relation and adaptation of P.
tenuiflora and L.dasystachs to saline soil. The result showed that as total soluble salt content(TSSC) increased, K content kept little changed or a tendency of increase respectively in the aboveground parts and in the root of the both plants. L. dasystachs had a higher selectivity ot K than P.tenuiflora, and selectivity to K kept unchanged in L.dasystachs and increased in P.tenuiflora with increased TSSC. When TSSC was 0.3%, Na contents and K/Na ratios of the aboveground parts were approximately equal in the two plants, while TSSC was higher, Na contents and K/Na ratios in L. dasystachs were 1/3～ 2/3 and 1.9～3.5 times that in P.tenuiflora. Cl contents were higher when TSSC was 0.3% and 1.29%, or lower when TSSC was 2.03% in P.tenuiflora than in L.dasystachs. Selectivity to K and abundant accumulation of Cl in plants were probably the cause of high salt-tolerance of the both plants, while K, Na and Cl contents and their ratios in the plants reflected the difference of salt-tolerance of the two plants from indirect sources , and a higher salt- tolerance of L.dasystachs was associated with its higher selectivity to K,K/Na ratio, Cl content( when TSSC was higher), and lower Na content as compared with lower that of P.tenuiflora.