Abstract: A sand culture pot experiment was conducted in order to investigate the effects of 3 NaCl stress levels of 0, 100, 200 mmol·L^-1 on seedling growth and distribution of Na⁺, K⁺, Ca²⁺ and Mg²⁺ in different organs of Portulaca oleracea. The results showed that under different levels of NaCl stress, dry weight of shoots and leaves number were decreased, while dry weight of roots and root/shoot ratio were increased. Among these three organs, content of Na⁺ was significantly increased compared with that of the contrast seedlings, and mainly concentrated in roots. Moreover, K⁺ contents dramatically decreased, and the decrease range of the K⁺ contents was larger in leaves and smaller in stems. Ca²⁺ and Mg²⁺ contents in leaves were dramatically higher than those in stems and roots. With the increase of NaCl stress concentration, ratios of K⁺/Na⁺, Ca²⁺/Na⁺, Mg²⁺/Na⁺ were decreased, primarily due to the increasing accumulation of Na⁺. Besides, ratios of K⁺/Na⁺, Ca²⁺/Na⁺, Mg²⁺/Na⁺ in leaves were relatively higher than those in stems and roots. The ability of ion-selective transportation from roots to stems of Portulaca oleracea seedlings increased first and then decreased, and that from stems to leaves gradually increased with the increasing NaCl stress. The results of comprehensive analysis indicated that Portulaca oleracea possibly protect seedlings from damage caused by NaCl stress via compartmentalization of Na⁺ into roots and increasing the upward transportation of K⁺, Ca²⁺ and Mg²⁺.

Key words: Portulaca oleracea L., NaCl, ion content