Salinity tolerance of 33 greens-type Poa annua experimental lines

Current literature suggests Poa annua L. (annual bluegrass) is intolerant to salinity stress. Response of greens-type Poa annua to chronic salinity stress (12 wk at 8.0 dS m^-1) was evaluated over two greenhouse experiments. Vegetative samples of 33 greens-type P. annua experimental lines were maintained at a 6.4-mm mowing height and irrigated daily with modified Hoagland's solutions possessing salinity levels of 0.7 dS m^-1 (nonsaline control) or 8.0 dS m^-1 (NaCl treatment, approaching 0.25 strength sea water, approx. 13.5 dS m^-1). Clipping yield dry weight (CYD) and leaf water content (LWC) were measured weekly. Digital images were collected at the end of weeks 1, 4, 8, and 12 to determine percentage cover (PC) and dark green color index (DGCI). Across all lines, all sample dates, and both experiments, salinity stress significantly reduced PC (30.8%), DGCI (9.3%), CYD (33.9%), and LWC (3.3%) compared with nonsaline controls (α = 0.05), suggesting chronic salinity stress is detrimental to greens-type P. annua quality. However, significant differences in relative PC and relative CYD were observed among lines, indicating that substantial variation in salinity tolerance exists in greens-type P. annua. Numerous greens-types P. annua experimental lines, such as PSU 99-9-21, PSU 01-1-46, and PSU 05-1-14, possess moderate-to-good salinity tolerance and are potentially suitable for use on golf courses with moderate salt problems.