E-G. Arithmetic means (n = 3) of Cu (E), Zn (F) and Ca (G) concentrations in maize grain, which were left untreated (control, white bar) or treated with nCu at dose of 20 mg/kg DW (black bar) or 1000 mg/kg DW (grey bar). * (P<0.05), ** (P<0.01) and *** (P<0.001) represent significant differences from control group, ANOVA