Responses of Creeping Bentgrass to Salt Stress During in Vitro Germination.

Many golf courses and turfgrass fields use recycled (effluent or reclaimed) water, which contains high salts,  as part or a sole irrigation source to lower costs and comply with governmental restrictions on water utilization. High salinity negatively affects turfgrass performance. Using salt-tolerant species or cultivars is one the most effective methods to address the salinity problem. 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, and 20 g L^-1 at 25/15 ºC (day/night) temperature under fluorescent light (36 μmol·s^-1·m^-2) with an 8- to16- h photoperiod. Significant variations in salinity tolerance were observed among the cultivars. ‘Declaration’, ‘Seaside II’, ‘T-1’, and ‘Bengal’ had 50% reduction in final germination percentage (FGP, %) and daily germination rate (DGR, % d^-1) when salinity levels were >16.0 and 10.0 d Sm^-1, respectively, indicating high salt tolerance. In contrast, salt-sensitive cultivars, ‘Tyee’, ‘Kingpin’, and ‘SR1150’, had 50% reduction in FGP and DGR when average salinity levels were 11.6 and 6.5 d Sm^-1, respectively. Final germination percentage and DGR decreased linearly or quadratically as salinity levels increased, with an average of 55 and 67% decrease in FGP and DGR, respectively, in 5 to 20 g L^-1 NaCl-containing medium. The largest difference between FGP (1.9 %) and DGR (26.2 %) reduction under saline conditions was observed at 5 g L^-1.  It indicated that DGR was more sensitive to salinity changes than FGP; therefore, DGR might be a more reliable method to be used to select salt tolerant germplasm.