(446) Salinity Tolerance of Eight Ornamental Herbaceous Perennials

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  • 1 1Utah State University, Plants, Soils, & Biometeorology, Logan, UT
  • | 2 2Washington State University, Plants, Soils, & Biometeorology
  • | 3 3Washington State University, Agronomy, Pullman

Although salinity is becoming an increasing concern for landscape plants in many areas of the West, few studies have been carried out to evaluate salinity responses of ornamental plants, especially herbaceous perennials. We investigated salinity tolerance of four traditionally grown and four Intermountain West native ornamental herbaceous perennials. Penstemo×mexicali `Red Rocks', Leucanthemum×uperbum `Alaska', Echinacea purpurea, Lavandula angustifolia, Geranium viscosissimum, Eriogonum jamesii, Penstemon palmeri, and Mirabilismultiflora were irrigated with water containing a mixture of 2 CaCl2: 1 NaCl at salinity levels of 0.33 (tap water control), 2.2, 5.4, and 8.3 dS·m-1 for 8 weeks. Growth, visual quality, and gas exchange were assessed. Mirabilis multiflora and L.×uperbum `Alaska' showed high salt tolerance based on visual quality. No noticeable leaf necrosis was observed for either species at any salinity level. However, over the 8-week period, growth rates for L. superbumwere reduced by 35%, 58%, and 72% compared to the control for the 2.2, 5.4, and 8.3 dS·m-1 salinity levels, respectively. The decrease in growth did not reduce visual quality. Growth rates for M. multiflora were slightly higher than the control for the 2.2 and 5.4 dS·m-1 salinity levels and dropped about 20% at the highest salinity level. Echinaceapurpureashowed the lowest tolerance to salinity, as evidenced by substantial margin burn at all salinity levels as well as high mortality; all plants in the highest salinity treatment died.