Responses of Ornamental Grass and Grasslike Plants to Saline Water Irrigation

Ornamental grasses are popular in urban landscapes in Utah and the Intermountain West United States, one of the driest and fastest growing regions in the United States. This experiment evaluated the responses of five ornamental grass species [blue grama (Bouteloun gracilis), indian sea oats (Chasmanthium latifolium), 'Blue Dune' sand ryegrass (Leymus arenarius), pink muhly grass (Mublenbergin capillaris), 'Foxtrot' fountain grass (Pennisetum alopecuroides)] and two ornamental grasslike species [fox sedge ( Carex vulpinoiden), common rush (Juncos effuses)] to saline irrigation water in a greenhouse. Plants were irrigated weekly with a nutrient solution at an electrical conductivity (EC) of 1.2 dS.m(-1) (control) or saline solutions at an EC of 5.0 or 10.0 dS.m(-1). At the first harvest (9 weeks after the initiation of treatment), sand ryegrass, pink muhly grass, and fountain grass irrigated with solutions at an EC of 5.0 and 10 dS.m(-1) had good visual quality with no or minimal foliar salt damage; however, the remaining species exhibited slight or moderate foliar salt damage. There were no significant differences in shoot dry weight (DW) among treatments within any species, except fox sedge and fountain grass. At the second harvest (18 weeks after the initiation of treatment), sand ryegrass, pink muhly grass, and fountain grass still had no or minimal foliar salt damage, and indian sea oats and fox sedge exhibited slight or moderate foliar salt damage. Compared with the control, all species irrigated with solutions at an EC of 10.0 dS.m(-1) had reduced shoot DWs with the exception of blue grama. However, only common rush and pink muhly grass irrigated with solutions at an EC of 5.0 dS.m(-1) had lower shoot DWs than the control. These results demonstrated that seven ornamental grass or grasslike species had a very strong tolerance to the salinity levels used in the 4-month experiment. Although plant growth was inhibited as a result of saline irrigation, plant visual quality of sand ryegrass, pink muhly grass, and fountain grass was still acceptable. These three species appear to be more suitable for landscapes in which saline irrigation water is used. Further research is needed to evaluate more ornamental grasses for landscapes in salt-prone areas and nearby coastal regions.