Irrigation water quality and ion balance in leaves of deciduous ornamental trees

In arid and semi-arid regions, evaporation losses exceed replenishment from fresh water tributaries reducing water quality due to accumulation of salts. Increasing human demand for high-quality waters has encouraged use of low-quality, nonpotable water for landscape and agricultural irrigation. However, when used alone for irrigation, growth and appearance of some woody ornamentals are negatively impacted. To date, little is known of the impacts of low-quality water on ion uptake and salt tolerance of most ornamental plants. Three replications of five deciduous ornamental trees were randomly planted and treated with three blended irrigation waters of high-, medium-, and low-quality water [15, 80, and 120 mg sodium (Na) L^-1, respectively] in a split-plot design. Leaf tissues were sampled on October 1996 and September 1997 and analyzed for nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), Na, zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu). The five tree species varied in their responses to irrigation treatment with water of decreasing quality with some having increasing and others decreasing contents of a specific nutrient element. Further, although impact of low-quality water was evident, none of the minerals tested were in the deficient or toxic range.