Fig. 3. Dry biomass of shoots (a) and roots (b) expressed as g per container (per 10 plants), and Cu concentrations (mg kg^-1 dry matter) of shoots (c) and roots (d) as a function of Cu concentration in the nutrient solution (µM) in the hydroponic experiment. Open symbols stand for values of preculture plants. Corresponding free Cu ion concentrations (µM) as calculated from the SOILCHEM computer code (Sposito and Coves, 1988) are also indicated. Mean values with different letters are significantly different (p < 0.05) as measured by the Ryan–Einot–Gabriel–Welsch–Range test.