Salt Tolerance Evaluation of Cool-Season Turfgrasses for Roadsides in Cold Climates.

Roadsides are challenging environments for turfgrass growth. One of the primary stresses along roadsides in northern climates is road salt. There is a need to continuously evaluate turfgrass species and cultivars for salt tolerance so that appropriate species and cultivar recommendations can be made to those who maintain roadside turfgrasses. In this study we evaluated 38 cultivars and accessions representing 15 grass species for salt tolerance at five levels of salt stress (0, 10, 14, 18, and 22 dS/m) over the course of 15 weeks. Grasses were sown in February, 2017 into 10.16 cm^2 pots filled with silica sand and established for 12 weeks. After establishment pots were transferred into two 760 L tubs where they were acclimated and then exposed to salt. Salt concentration started at 0 dS/m for three weeks and then was increased to the next highest salt concentration treatment (10 dS/m); the concentration continued to be increased to the remaining treatment levels every three weeks. The experiment was a randomized complete block design, with three replications per tub. Turfgrass was evaluated for percent green cover based on digital image analysis, electrolyte leakage, and Normalized Difference Vegetative Index (NDVI). At 22 dS/m, tall fescue maintained green color and performed well, while nearly all other grasses senesced. A few species, such as slender creeping red fescue, strong creeping red fescue, perennial ryegrass and tetraploid perennial ryegrass tolerated salt stress at the lower treatment levels, but eventually succumbed to the stress at 18 dS/m. These results suggest that tall fescue should be considered for sites where salt stress is a known problem. Ultimately, other considerations, such as heat stress tolerance and overall winter hardiness must also be factored into roadside turfgrass species recommendations.