The roots of both maize crops were uprooted manually and washed
in 0.02 mol L−1 ethylenediaminetetraacetic acid (EDTA) at 35 DAE. The
shoots were cut close to the soil surface, and a leaf samplewas immediately
frozenwith liquid N2 and stored in an ultra-freezer at−80 °C until
biochemical analyses. The remaining leaf and root samples were dried
in a forced-air oven at 65 °C until reaching a constant dry matterweight
and then ground in a Wiley mill. The total Cu and Zn concentrations
in the leaves and roots were assessed after digesting the samples in a
muffle furnace. The samples were calcined at 500–550 °C for 3 h, and
the resulting ashes were diluted in a solution with 1 mol L−1 of