Water quality and conservation are at the forefront of public environmental concerns; hence, greenhouse operations particularly in Europe, Israel, and California are reorganizing and investing in their irrigation practices (Morgan and Reed, 1998). As supply of high-quality water decreases growers are being forced to irrigate their crops with poor-quality water and/or saline water (Lieth and Burger, 1989). Use of recycled water to irrigate floriculture bedding plants may be warranted in the future because of declining freshwater supply and increasing human population (Niu and Rodriguez, 2006). In regions lacking outlets for agricultural drainage disposal or where water supply is scarce, the recycling of drainage waters for irrigation increasingly is seen as a viable management option (Skaggs et al., 2006).
Treated municipal effluent has been used for irrigation of golf courses and some horticulture crops, particularly citrus (Citrus spp.) orchards, in many areas of the United States (Niu and Rodriguez, 2006). For example, in Florida 92,345 ha of land was irrigated with reclaimed municipal water in 2005; 6144 ha was agricultural land and the rest was used for irrigating golf courses and landscapes (Morgan et al., 2008).
Besides reclaimed municipal water, there are additional sources of salt in irrigation water. Road deicing salts in northern locations can salinize irrigation water (Lerner, 2006) hampering plant production. Intrusion of seawater into underground aquifers is also a severe problem in some coastal areas (Lerner, 2006). The need to develop new, innovative, and more efficient agricultural water management systems is essential to developing sustainable irrigation (Skaggs et al., 2006).
To our knowledge, floriculture breeding programs are not actively selecting new cultivars for salt tolerance; however, biotechnology approaches have been increasingly investigated (Xu et al., 2009).
As a result of the current and increasing use of saline irrigation water, it is imperative for the floriculture industry to determine the salt tolerance of commonly used greenhouse bedding plants to minimize potential salt damage before the use of nonpotable water sources are mandated. Such research has been conducted for five herbaceous perennials grown in the landscape in the arid and semiarid southwestern United States (Niu and Rodriguez, 2006). To our knowledge, the last significant screening of herbaceous annuals (bedding plants) took place over two decades ago (Tija and Rose, 1987). Clearly, plant materials have changed greatly over the intervening years justifying another look at salt tolerance in bedding plants.
In this work, we characterized the response during greenhouse production of 14 popular floriculture species exposed to different levels of NaCl salinity in the irrigation water. We aim to find clusters of plants that respond similarly to elevated salts so that we may classify species on the basis of how sensitive they are for practical management guidelines.
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