There was a two-way interaction between the tissue type and concentration for Zn and Ce concentration in the tubers while for Cu there was three-way interaction between tissue type, concentration, and form (Fig. 1). A general concentration-dependent increase was observed for metal concentrations of each element with peels showing the highest concentration. The magnitude of the difference in peel concentration relative to that of unpeeled or peeled tubers was greatest for Ce and least for Zn. The concentration of Cu and Ce in peeled tubers was typically significantly less as compared to unpeeled tubers.