Fig. 4. Concentrations (a) and amounts (b) of Cu in plant shoots and roots expressed as mg kg^-1 dry matter and µg per container (per 10 plants), respectively. NS and H₂O stand for nutrient solution and deionized water treatments, respectively. Percentages of total root Cu bound to root cell walls are indicated in (a). Mean values with different letters are significantly different (p < 0.05) as measured by the Ryan–Einot–Gabriel–Welsch–Range test.