2018 ASHS Annual Conference

Ornamental grasses are popular in urban landscape in Utah and the Intermountain West, one of the driest and fastest growing regions in the United States. An estimated $158 million worth of ornamental grasses are sold annually in U.S. Alternative water sources such as graywater and reclaimed municipal water are becoming important resources for landscape irrigation. These water sources are known to carry relatively high levels of salts, which negatively affect plant growth and development. Therefore, understanding the salinity tolerance of different ornamental grasses can be beneficial for preventing salt damage to ornamental plants while maintaining appealing landscapes. Five ornamental grass species [Bouteloua gracilis (blue grama), Chasmanthium latifolium (inland sea oats), Leymus arenarius 'Blue Dune' (sand ryegrass), Muhlenbergia capillaris (pink muhlygrass), and Pennisetum alopecuroides 'Foxtrot' (foxtail fountain grass)] and two ornamental grass-like species [Carex vulpinoidea (fox sedge) and Juncus effuses (common rush)] were assessed for salinity tolerance 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 solution at EC of 5.0 dS∙m^-1 (EC 5) or 10.0 dS∙m^-1 (EC 10) for eight weeks. At nine weeks after the initiation of treatment, in EC 5, L. arenarius, M. capillaris and P. alopecuroides had no foliar damage with a visual score of 5 (0: dead; 5: excellent), while J. effuses, B. gracilis, C. latifolium, and C. vulpinoidea showed some foliar damage with an averaged visual score of 4.5, 3.8, 3.7, and 3.0, respectively. In EC 10, L. arenarius, M. capillaris, P. alopecuroides, J. effuses, and B. gracilis exhibited no or minimum foliar damage with an averaged visual score of 4 or greater. However, C. latifolium and C. vulpinoidea had slight foliar damage with averaged visual scores of 3. Compared to control, shoot dry weight (DW) of C. vulpinoidea in both EC 5 and EC 10 was decreased by 16%, whereas shoot DW was reduced by 24% and 54% for P. alopecuroides in EC 5 and EC 10, respectively. The reduction in shoot DW in other species was no significant. This experiment is still underway to select the most salt tolerant ornamental grasses for aesthetically appealing landscape that is irrigated with alternative waters.