This study established gradient stress treatments of pH， NaCl， NaHCO₃， and Na₂CO₃ to compare the stress tolerance differences between Leymus chinensis and Elymus dahuricus. Evaluated parameters included growth indices such as seedling leaf length， root length， and fresh weight， as well as physiological indicators including chlorophyll content， relative electrical conductivity， malondialdehyde （MDA） content， superoxide anion （O₂^-·） content， antioxidant capacity， and osmoregulatory substance levels in mature leaves. A comprehensive evaluation was conducted using principal component analysis （PCA） in conjunction with the membership function value （MFV） method. The results demonstrated that alkaline salts （NaHCO₃， Na₂CO₃） exhibited significantly stronger inhibitory effects compared to neutral salt （NaCl） and high pH conditions. With increasing Na⁺ concentration and pH levels， the growth inhibition of L. chinensis was less pronounced than E. dahuricus. Additionally， L. chinensis exhibited a smaller reduction in chlorophyll content， lower increase in relative electrical conductivity and malondialdehyde （MDA） levels， less accumulation of superoxide anion radicals （O₂^-·）， and stronger antioxidant capacity compared to E. dahuricus. Additionally， L. chinensis accumulated higher levels of osmoregulation substances （soluble sugars， soluble proteins， proline）. The PCA-MFV comprehensive evaluation confirmed consistent conclusions between seedling phenotype and mature plant physiological indices， demonstrating that L. chinensis possessed significantly superior comprehensive saline-alkali tolerance compared to E. dahuricus. This research provides a theoretical foundation for vegetation selection and breeding in saline-alkali soil.

Leymus chinensis  /  Elymus dahuricus  /  Saline-alkali stress  /  Physiological index  /  Principal component analysis