LAUSR

Due to a zinc-deficient diet, about 800,000 children die each year worldwide. This aspect is amended by exploiting foliar fertilization, a useful alternative to improve crop yield and nutritional quality of food crops. The aim of this study was then to investigate the leaf uptake and transport of zinc by soybean (Glycine max (L) Merrill). Plant leaves were treated with Zn phosphite and Zn ethylenediamine tetra-acetic acid (EDTA) commercial formulations. X-ray spectroscopy (XRF and XANES) was exploited to trace nutrient movement in the petiolule and scanning electron microscopy (SEM) to evaluate the influence of leaf surface treatments. No radiation damage, in terms of elemental redistribution, was observed during the XRF and XANES measurements. As an alternative to radioisotopes, XRF allowed to detect the movement of Zn from both sources in the plant petiolule. Both fertilizers disintegrated leaf epicuticular wax crystals, yet accumulation of sediments in the vicinity of stomata was noted only for Zn phosphite. Absorption and redistribution of Zn were higher for plants that received Zn phosphite. Zinc supplied as Zn phosphite was transported in a form different from that of the pristine Zn phosphite, whereas Zn supplied as Zn EDTA was transported in its chelated form.