Conservation of water is a critical issue worldwide in the arid and semiarid regions. Water of good quality is predicted to become scarcer as a result of competition among a rapidly increasing urban population and industrial development (Niu and Rodriguez, 2006). Many cities and districts have trouble balancing water demands of agricultural, landscape, industrial, and domestic users (Qian and Mechan, 2005). Irrigation of the increasing urban landscapes associated with urban settings (Loram et al., 2007) consumes large quantities of water. For example, in the arid Mountain West of the United States, landscape irrigation is estimated to account for up to 50% of the municipal yearly water used during the spring to fall season (Kjelgren et al., 2000). Other estimations indicate that in cities in the desert of the southwestern United States, landscape irrigation consumes up to 90% of all the water used by a single family (Sovocool et al., 2006).
According to Qian and Mechan (2005), the population increase has also increased the volume of wastewater generated, which, once recycled or treated and used for irrigation, is viewed as one of the approaches to maximize the existing water resources. Landscape irrigation is the second largest user of reclaimed water in industrialized countries (Asano, 2002). Recycled or wastewater is a valuable resource that may mitigate the use of potable water for irrigation purposes. However, reclaimed water represents a significant concern for plant production and performance in the landscape because it may be high in soluble salts (Ammary, 2007), which may increase salinity of soil or growing medium (Lindsey et al., 1998), thus limiting its use for landscape irrigation (Zollinger et al., 2007). Salinity may affect the growth of ornamental shrubs by reducing stem growth and leaf expansion resulting from osmotic effects or by toxicity resulting from high ionic concentration of constituents such as Na+ and Cl–, typical of reclaimed wastewater (USEPA, 1992). Excessive Na+ and Cl– concentration in plant tissues may reduce visual quality of ornamental plants by inducing leaf necrosis or bronzing. However, in ornamental horticulture, short-stature plants are not necessarily associated with poor quality as demonstrated in marigold (Valdez-Aguilar et al., 2009). The use of salt-tolerant species is a viable option that should be considered in landscaping projects (Cassaniti et al., 2009). Species that maintain acceptable growth rates and that also possess mechanisms to exclude Na+ and Cl– from transport to sensitive organs and that still remain attractive despite irrigation with saline water are ideal for landscaping under such conditions. The present study was conducted to determine the growth and visual quality responses and nutritional ion imbalances of selected landscape shrub species subjected to irrigation with water of increasing NaCl + CaCl2 concentrations during container production.
Black, R.J. 2003 Salt-tolerant plants for Florida Department of Environmental Horticulture, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. ENH26
Cramer, G.R., Lauchli, A. & Polito, V.S. 1985 Displacement of Ca2+ by Na+ from the plasmalemma of root-cells—A primary response to salt stress Plant Physiol. 79 207 211
Duman, F., Cicek, M. & Sezen, G. 2007 Seasonal changes in metal accumulation and distribution in common club rush (Schoenoplectus lacustris) and common reed (Phragmites australis) Ecotoxicology 16 457 463
Jarecki, M.K., Chong, C. & Voroney, R.P. 2005 Evaluation of compost leachates for plant growth in hydroponic culture J. Plant Nutr. 28 651 667
Lindsey, P., Harivandi, M.A. & Setka, G. 1998 Recycled landscape irrigation water and ornamental plant compatibility study. Slosson Report 1996–1998 29 Feb. 2008 <http://groups.ucanr.org/slosson/documents/1995-19982110.pdf>.
Loram, A., Tratalos, J., Warren, P.H. & Gaston, K.J. 2007 Urban domestic gardens (X): The extent & structure of the resource in five major cities Landscape Ecol. 22 601 615
Miyamoto, S. 2008 Salt tolerance of landscape plants common to the southwest. Texas AgriLife Research and Extension Center Texas A&M University System in cooperation with Texas Water Resource Institute and El Paso Water Utilities, El Paso, TX. TR-2008–316
Moya, J.L., Primo-Millo, E. & Talon, M. 1999 Morphological factors determining salt tolerance in citrus seedlings: The shoot to root ratio modulates passive root uptake of chloride ions and their accumulation in leaves Plant Cell Environ. 22 1425 1433
Qian, Y.L. & Mechan, B. 2005 Long term effects of recycled wastewater irrigation on soil chemical properties on golf course fairways Agron. J. 97 717 721
Schachtman, D. & Liu, W. 1999 Molecular pieces to the puzzle of the interaction between potassium and sodium in plants Trends Plant Sci. 4 281 287
Sovocool, K.A., Morgan, M. & Bennett, D. 2006 An in-depth investigation of xeriscape as a water conservation measure American Water Works Association Journal 98 81 93
Valdez-Aguilar, L.A., Grieve, C.M., Poss, J. & Layfield, D. 2009 Salinity and alkaline pH of irrigation water affect growth of marigold plants: II. Mineral ion relations HortScience 44 1726 1735
Wakeel, A., Abd-El-Motagally, F., Steffens, D. & Schubert, S. 2009 Sodium-induced calcium deficiency in sugar beet during substitution of potassium by sodium J. Plant Nutr. Soil Sci. 172 254 260
Zollinger, N., Koenig, R., Cerny-Koenig, T. & Kjelgren, R. 2007 Relative salinity tolerance of intermountain western United States native herbaceous perennials HortScience 42 529 534