Fig. 1: SEM micrographs of leaf surfaces of mature apple leaves and micro-XRF mapping of Zn in the cross‐sections of leaves after foliar Zn application.

(a) SEM micrographs of leaf surfaces of apple mature leaves, showing that mature apple leaves have a heterogeneous topography between adaxial (left) and abaxial (right) leaf surfaces. (b) Micro-XRF mapping of Zn in the crosssections of leaves after foliar Zn application, showing the different efficiencies of Zn absorption in adaxial and abaxial leaf surfaces. In each section, the adaxial side is to the left. Fluorescence intensities (counts s-1) of Zn were normalized and scaled between red (maximum) and blue (minimum) for each map