Abstract: By the method of hydroponics, this paper studied the effects of different concentration NaCl on the allocation of K⁺, Na⁺ and Cl^- in the seedlings of two Cucumis sativus L. cultivars with different levels of salt-tolerance. The results showed that under NaCl stress, the seedlings K⁺ content decreased, while their Na⁺ and Cl^- contents increased, with the increase in salinity. Among the test organs, stem had the highest content of Na⁺ and Cl^-, while upper leaves had the lowest. The decrease of K⁺ content in upper leaves was less than that in other organs. Compared with salt-susceptible cultivar ‘Jinchun No. 2’, salt-resistant cultivar ‘Changchun Mici’ had a higher transportation selectivity of K⁺ to Na⁺ from root to stem, and of K⁺ to Na⁺ and Cl^- to Na⁺ from stem to upper leaves, and retained more Na⁺ in root. As a result, ‘Changchun Mici’ accumulated more K⁺ and less Na⁺ in its leaves, and the ratios of leaf K/Na and Cl/Na were higher.‘Changchun Mici’ also had a higher biomass than ‘Jinchun No. 2’ under same salinity. All of these suggested that the higher accumulation of Na⁺ in roots and the lower transportation selectivity of Na⁺ from stem to upper leaves were the main reasons for the stronger salt-tolerance of ‘Changchun Mici’.

Key words: Pest, Natural enemy, Jujube orchard, Community succession, Interaction