Cuticular retention, foliar absorption and translocation of Fe, Mn and Zn supplied in organic and inorganic form

Abstract

As chelates are commonly used in practice for soil fertilization and the interest of their extension to foliar fertilization is still in discussion, the purpose of this study was to specify some aspects of their behaviour when applied to leaves in comparison with inorganic forms. Since the first barrier to overcome in foliar nutrition is the cuticle, experiments were carried out with isolated Tomato fruit cuticles considered as model, in order to compare the cuticular affinities for respectively, inorganic and organic (EDTA) forms of iron, manganese and zinc. It was found that, except in the case of iron where no significant difference was observed, the cuticular Sorption was lower with EDTA than with the inorganic forms. Parallel experiments were performed on whole Pea plants, in order to measure the levels of absorption and translocation in situ of Fe, Mn and Zn applied on leaves, in the form of either the EDTA chelate or the sulfate salt. For both kinds of compounds extensive fixation occurred in the treated area. The three elements were less absorbed as chelates than as inorganic salts, in accordance with results on isolated cuticles, while further translocation within the plant was much greater with chelates. However, the combination of these two parameters, uptake and translocation, sometimes raises the question of the actual interest of chelates as foliar fertilizers with respect to their higher cost, and that without regard to any possible positive effect they may have on other components of the yield.

Key Words:

• Cuticular retention
• foliar absorption
• translocation
• iron
• manganese
• zinc
• EDTA‐Fe
• EDTA‐Zn
• EDTA‐Mn