三种胁迫下紫花苜蓿萌发期耐盐碱性评价及其生理响应规律OA

This study aimed to systematically evaluate the salt-alkali tolerance of alfalfa(Medicago sativa L.)at the germination stage under complex saline-alkali environments and to screen germplasm resources with broad adaptability and stress resistance.Twenty-six alfalfa accessions from different sources were selected and subjected to three stress treatments determined by concentration-gradient screening:200 mmol/L NaCl(salt stress),60 mmol/L NaHCO3(alkali stress),and a combined stress of 50 mmol/L NaCl+50 mmol/L NaHCO3.Eight germination indices,including germination potential,germination percentage,root length,and vigor index,were measured.The membership function method and cluster analysis were used to comprehen-sively evaluate the salt-alkali tolerance of the tested accessions,and representative accessions were further vali-dated using physiological indices.The results showed that different stress types exerted distinctly different inhibitory effects on alfalfa at the germination stage.To obtain an equivalent inhibitory effect,alkali stress required a far lower molar concentration than salt stress,with stronger damaging effects per unit concentration.Cluster analysis revealed significant differences in salt-alkali tolerance among the tested accessions under the three stresses.Although 'WL3251HQ' performed best under single salt stress,it was extremely sensitive to alkali stress.'Felicia' and 'Aurora' ranked among the top in D values under all three stress environments,dem-onstrating excellent and stable comprehensive salt-alkali tolerance,and were classified as strongly salt-alkali-tolerant accessions.'Dripperstar(Multi-Leaf)' and 'WL366HQ' were identified as salt-alkali-sensitive acces-sions.Physiological verification showed that the strongly salt-alkali-tolerant accession Aurora could maintain high antioxidant enzyme activities under stress and effectively alleviate membrane lipid peroxidation,and its physiological response patterns were consistent with the results of the comprehensive evaluation.This study screened accessions with stable performance under multiple salt-alkali stresses,thereby providing a theoretical basis and material foundation for alfalfa breeding and cultivation in salt-alkali land.