Tolerance mechanisms of Leymus chinensis to salt–alkaline stress

The salinization–alkalization of soil is an increasing environmental problem and a limiting factor for plant growth and productivity. This paper studied the morphological and physiological response of rhizomes of Leymus chinensis, which grows rapidly and is highly tolerant to arid and saline–alkaline soils, to different levels of saline–alkali stress. Biomass and density of rhizomes showed a variation along with the increase in saline–alkali stress; they show the maximum level in a saline–alkali medium. Rhizome internode length and specific root length gradually increased, while root biomass indicated a contrary tendency towards increase in saline–alkali stress. Under different saline–alkali stress, the root–shoot ratio showed no significant differences among groups. The variation in Na⁺ content was increased with the increase in saline–alkali stress. The contents of K⁺ and proline were the highest in a saline–alkali medium; under different levels of salt–alkali stress, the presence of organic acids (OAs) showed different changes. Citrate, malate and succinate were the dominant OAs accumulated in rhizomes. The activity of superoxide dismutase, catalase and peroxidase increased with incrementing salt–alkaline stress. In summary, L. chinensis is likely to exert a series of adaptable response on its physiology and morphology under different levels of salt-alkaline stress. Further study on large-scale cultivation of the L. chinensis would be beneficial for the ecological recovery and exploitation of the salt-alkalinized soil.