Fig. 2

Variation in tissue Na⁺、K⁺ content and K⁺/Na⁺ ratio in the four test species in response to salinity stress. a Na⁺ content in the root, b Na⁺ content in the stem, c Na⁺ content in the leaf, d K⁺ content in the root, e K⁺ content in the stem, f K⁺ content in the leaf, g K⁺/Na⁺ ratio in the root, h K⁺/Na⁺ ratio in the stem, i K⁺/Na⁺ ratio in the leaf. *,**: means differ significant from levels in the control treatment (P < 0.05 and < 0.01, respectively)