2.4. Nutrient, EC and pH determination
Leaf samples were collected, washed with distilled water, and oven dried for 48 h at 65 8C in paper bags. Samples were ground and digested as described by Chapman and Pratt (1961). Nutrient concentrations were determined by an inductively coupled plasma atomic emission analyzer (Varian-Vista-MPX, CCD simultaneous ICP-OES Axial). Nitrogen was analyzed by Kjeldahl procedure. Soil samples were collected from pots and prepared for nutrient analysis as described by Chapman and Pratt (1961). Nitrogen was analyzed by Kjeldahl procedure. Phosphorus was measured by spectrophotometer. Potassium and sodium concentrations were determined by emission flame photometry. The micronutrients were analyzed by the atomic absorption spectrophotometer (Varian, SpectrAA 220 FS). Soil electrical conductivity and pH were analyzed in a 1:2.5 soil extract by an EC and a pH meter, respectively.