Abstract
Energy dispersive X-ray microanalysis (EDX) is a convenient method for analyzing mineral compositions of forage, especially when sample size is limiting. This requires, however, that the sample is a representative of the whole plant in mineral concentrations. To find which organ is best suited for estimating whole plant mineral concentrations, two experiments were conducted. In Experiment 1, the relationships between several organs and whole plant magnesium (Mg) concentration were investigated using wet chemical analysis. Magnesium concentrations of whole plant were closely correlated with those of leaf sheaths, stubbles and lower leaf blades. In Experiment 2, Mg densities for three orchardgrass groups selected for contrasting herbage Mg concentration were analyzed using EDX. Tissue Mg densities differed most among groups for leaf sheath at Harvest 1 and in leaf sheath, leaf blade and stubble at Harvest 3. Leaf sheath appeared to be the most suitable organ for estimating whole plant Mg using EDX analysis.
