Responses of traditionally grown and intermountain West native ornamental herbaceous perennials to drought and salinity

Drought and salinity tolerance were assessed for several Intermountain West native and traditionally used ornamental herbaceous perennials. We irrigated six species established in pots at intervals of 1, 2, and 4 weeks, simulating well watered conditions, moderate drought, and severe drought. Penstemon barbatus showed high tolerance to drought. Lavandula angustifolia and Penstemon x mexicali 'Red Rocks' tolerated moderate drought, but died when exposed to severe drought. Gaillardia aristata and Leucanthemum x superbum 'Alaska' displayed drought avoidance mechanisms in moderate and severe drought. Additionally, we irrigated eight species with water containing CaCl2 and NaCl (2:1 molar ratio) at levels of 0, 1000, 3000, and 5000 mg·L-1 for eight weeks. Mirabilis multiflora, L. x superbum, and L. angustifolia showed high salinity tolerance at levels up to 5000 mg·L-1 but salinity reduced dry shoot and root weights for L. x superbum. Echinacea purpurea exhibited the lowest salinity tolerance of any of the species.