Responses of Creeping Bentgrass to Salt Stress during In Vitro Germination

Many golf courses and turfgrass managers use recycled water, which contains high salts, as part or a sole irrigation source to lower costs and comply with governmental restrictions on water use. High salinity negatively affects turfgrass performance. Using salt-tolerant species or cultivars is one the most effective methods to address salinity problems. Twenty-six commercially available creeping bentgrass (Agrostis stolonifera) cultivars were evaluated for salt tolerance during in vitro germination on 1% agar media supplemented with NaCl at 0, 5, 10, 15, or 20 g.L-1) at 25/15 degrees C (day/night) under fluorescent light (36 mu mol.s(-1.)m(-2)) with an 8- to 16-h photoperiod. Significant variations in salinity tolerance were observed among the cultivars. Final germination rate (FGR, %) and daily germination rate (DGR, %/d) decreased linearly or quadratically as salinity levels increased. 'Declaration', 'Seaside II, `T-1', and 'Bengal' were the most salt-tolerant, requiring salt levels at or greater than 16.0 and 10.0 g.L-1, respectively, to reduce FGR and DC R by 50%. In contrast, `Tyee', 'Kingpin', and 'SR1150' required average salinity levels of 11.6 and 6.5 0,-1 to cause 50% reduction in FCR and DGR, respectively, showing that they were the least salt-tolerant cultivars. The largest difference between FGR (1.9%) and DGR (26.2%) reduction under saline conditions was observed at 5 indicating that DGR was more sensitive to salinity changes than FGR. Therefore, DGR might be a more reliable method to be used for salt selection.