Elemental Analysis of Plant Leaves

Air-dried leaf samples (leaf blades) were ground and dry-ashed in concentrated HNO₃ vapours, and the ash was dissolved in a 3% HCl solution. Wet digestion in H₂SO₄ and HNO₃ was used for N and S detection, respectively. Atomic absorption spectroscopy, using an acetylene-air flame atomizer (Perkin Elmer AAnalyst 700) and microwave plasma atomic emission spectrometry (4200 MP-AES, Agilent), was used for the measurement of K, Ca, Mg, Fe, Mn, Zn, and Cu according to the manufacturer’s instructions. Levels of P, Mo, N, and B were determined by colorimetry: P by ammonium molybdate in an acid-reduced medium, Mo by thiocyanate in a reduced acid medium, B by hinalizarine in a sulphuric acid medium, N by modified Kjeldal method using Nessler’s reagent in an alkaline medium, and S through the turbidimetric method by adding BaCl₂, using a spectrophotometer Jenway 6300 as described previously [60 (link)]. All the values were expressed as mass % and mg kg⁻¹ on a dry matter basis for each macronutrient and micronutrient evaluated, respectively.