Interdependence of pH, malate concentration, and calcium and magnesium concentrations in the xylem sap of beech roots

The presence and concentration of mineral nutrients and organic acids were analyzed in root xylem sap of mature beech trees (Fagus sylvatica L.). An interdependence between malate concentration, pH, and calcium and magnesium concentrations was observed. Significant correlations were found between low pH values and high calcium and magnesium concentrations, low pH values and high malate concentration, and high malate concentration and high total calcium and magnesium concentrations. The observed correlations suggest that malic acid determines the chemical milieu of the xylem sap and tends to form complexes with hydrated or exchangeable adsorbed cations, thereby influencing the mobilization and translocation of calcium and magnesium in beech sapwood.