Tolerance of 30 Kentucky bluegrass varieties to NaCl stress during the seedling stage

To explore the genetic resources of Kentucky bluegrass (Poa pratensis) with strong salt tolerance, we evaluated the salt tolerance of 30 commercial Kentucky bluegrass varieties at the seedling stage. A range of growth and physiological indicators including plant height, tiller number, biomass, chlorophyll content, and leaf relative water content were determined under 400 mmol·L⁻¹ NaCl stress. A comprehensive evaluation was carried out using principal component analysis. The results indicate that salt stress inhibited the growth of all Kentucky bluegrass varieties. Compared to the control (without salt treatment), plant height and shoot fresh weight of ‘Kentucky’ decreased by 32.62% and 18.14%, respectively, after salt treatment. ‘Blue Best’ was the most severely impacted variety, with a 71.80% reduction in shoot fresh weight and dry weight decreased by and a 53.29% reduction in shoot dry weight due to salt stress. Furthermore, the chlorophyll content of ‘Kentucky’ ‘Euromyth’ ‘Moonlight’ ‘Explorer’ and ‘Arcadia’ decreased by approximately 20% following salt treatment. ‘Blue Coat’ experienced a notable 71.40% decrease in chlorophyll content, while the total chlorophyll content of ‘Fullmoon’ decreased by 55.70%. Additionally, under salt treatment, the leaf relative water content of ‘Blue Coat’‘Fullmoon’ and ‘Merit’ decreased by more than 22% compared to the control. Based on the comprehensive evaluation scores for salt tolerance, ‘Kentucky’‘Arcadia’‘Explorer’‘Moonlight’ and ‘Euromyth’ demonstrated strong salt tolerance, whereas ‘Blue Coat’‘Fielder’‘Merit’‘Blue Best’ and ‘Fullmoon’ proved to be sensitive to salt stress.