The use of microbial siderophores for foliar iron application studies

Experiments were conducted to assess the distribution of foliar applied Fe-containing compounds using microbial siderophores. Fe was measured in leaf fluid obtained by centrifugation according to a determination method based on Fe chelation by desferrioxamine E and HPLC separation on a reversed phase column. To avoid sample Fe contamination, treatments were only applied to a part of the leaf following a systematic and reproducible procedure and iron concentration was exclusively determined in fluid obtained from non-treated leaf surfaces. The increase in leaf fluid Fe concentration associated with the distribution of leaf applied Fe-siderophores, Fe–EDTA and FeSO₄ × 7H₂O was evaluated using Vicia faba L., Nicotiana tabacum L. and Citrus madurensis Lour. plants. The method proved useful to investigate the process of leaf Fe penetration and its distribution within the plant. Evidence of the penetration and distribution of leaf applied Fe-rhizoferrin, Fe-coprogen hydrolysis products and Fe-dimerum acid is presented in this study.