Effects of saline-alkali stress on the functional traits and physiological characteristics of Leymus chinensis leaves

To explore the effects of saline-alkali stress on the functional and physiological characteristics of Leymus chinensis leaves, L. chinensis plants were subjected to severe saline-alkali (pH = 9.73, electrical conductivity [EC] = 0.637 mS/cm), moderate saline-alkali (pH = 8.76, EC = 0.451 mS/cm), and control (pH = 7.37, EC = 0.22 mS/cm) soil treatments. Leaf functional traits, ion content, photosynthetic parameters, and antioxidant enzyme activity were determined, and the relationship between the functional traits and physiological characteristics was analyzed. With an increase in saline-alkali stress, the leaf density of L. chinensis decreased significantly (p < 0.05), the leaf mass per area (LMA) did not change significantly, and the leaf biomass ratio decreased significantly (p < 0.05). The Na⁺ mass fraction increased, and the K⁺ and Ca²⁺ contents and K⁺/Na⁺ and Ca²⁺/Na⁺ ratios decreased in response to saline-alkali stress. Except for intercellular CO₂ concentration, net photosynthetic rate, stomatal conductance, and transpiration rate were lower under saline-alkali stress. Except for dehydroascorbate reductase, the antioxidant enzymes increased significantly as a result of saline-alkali stress. Leaf density and leaf biomass ratio were significantly correlated with the measured physiological indicators except for net photosynthetic rate and peroxidase. Further study on large-scale cultivation of L. chinensis would be beneficial for the ecological recovery and exploitation of the saline-alkali soil.