To screen out high-quality salt-tolerant Lolium multiflorum germplasm resources， the salt tolerance of 50 accessions of Lolium multiflorum with different ploidy levels were evaluated in this study. Under different NaCl concentration treatments of 0， 50， 100， 150， 200 and 250 mmol·L^-1， the root length， shoot length， germination rate， germination potential， germination index， and vigor index after seed germination were measued. Salt tolerance of the experimental materials was assessed by using correlation analysis and other methods. The results showed that the D values of the 50 materials ranged from 0.037 to 0.972. At a Euclidean distance of 13.5， the 50 accessions were classified into 1 salt-tolerant accession， 9 moderately salt-tolerant accessions， 15 moderately salt-sensitive accessions， and 25 salt-sensitive accessions. Salt stress treatment of the screened extreme materials with different ploidy at the seedling stage showed that both plant height and biomass were inhibited， while relative water content and chlorophyll content were decreased， indicating that plant growth and physiological processes were suppressed under salt stress. Comprehensive comparison between the seed germination and seedling stages revealed that tetraploid Lolium multiflorum germplasm exhibited better salt tolerance than diploid materials. The findings provide theoretical support for breeding salt-tolerant Lolium multiflorum materials.

Lolium multiflorum  /  Salinity stress  /  Germination period  /  Seedling stage  /  Physiological characteristic