Abstract: 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.

Key words: Leymus chinensis, Elymus dahuricus, Saline-alkali stress, Physiological index, Principal component analysis

摘要： 本研究设置pH，NaCl，NaHCO₃与Na₂CO₃的梯度胁迫处理，比较羊草（Leymus chinensis）与披碱草（Elymus dahuricus）的抗性差异。测定的指标包括幼苗叶长、根长、鲜重等生长指标，以及成熟叶片中叶绿素含量、相对电导率、丙二醛（Malondialdehyde，MDA）含量、超氧阴离子（Superoxide anion，O₂^-·）含量、抗氧化能力与渗透调节物质含量等生理指标，并通过主成分分析（Principal component analysis，PCA）结合隶属函数分析法（Membership function value，MFV）进行综合评价。结果显示，碱性盐（NaHCO₃，Na₂CO₃）抑制效应显著强于中性盐（NaCl）及高pH条件下的一致效应。随Na⁺浓度、pH值升高，羊草的生长受抑程度小于披碱草。羊草的叶绿素含量降幅也低于披碱草，其相对电导率及MDA含量增幅更低，O₂^-·积累更少，抗氧化能力更强。羊草渗透调节物质（可溶性糖、可溶性蛋白、脯氨酸）积累量更高。PCA-MFV综合评价分析证实幼苗表型与成株生理指标结论一致，羊草综合耐盐碱能力显著优于披碱草。本研究为盐碱地植被选育提供理论依据。

关键词: 羊草, 披碱草, 盐碱胁迫, 生理指标, 主成分分析