title: Use of the stable isotope (57) Fe to track the efficacy of the foliar application of lignosulfonate/Fe(3+) complexes to correct Fe deficiencies in cucumber plants.
abstract: BACKGROUND
  During the last decade, environmental concerns regarding the use of recalcitrant synthetic chelates to overcome iron chlorosis has increased and new ligands such as lignosulfonates (LS) have been evaluated. However, the efficacy of these products is variable. In this work a hardwood (eucalyptus) and softwood (spruce) LS were compared to try to relate their physico-chemical characteristics and their efficacy. Also two more products derived from the eucalyptus lignosulfonate were tested.
  
  
  RESULTS
  All the LS tested presented a good ability to complex Fe, but only the spruce LS was capable to maintain significant amounts of soluble Fe above pH 8. According to the FTIR data, structural changes related to the Fe source (Fe(2+) or Fe(3+) ) used to form the complex occurred in the LS molecule and might influence their efficacy. Cucumber (Cucumis sativus L. cv Ashley) chlorotic plants were used to test lignosulfonate efficacy when applied through foliar sprays in comparison with FeSO(4) and EDTA/(57) Fe(3+) . The (57) Fe content of plants sprayed with LS was very low in respect to the EDTA treatment, but this was not reflected in the biomass and re-greening rates. Eucalyptus LS modifications improve its efficacy for iron chlorosis recovery to levels similar to those found for the spruce LS. Two applications of the LS are recommended.
  
  
  CONCLUSIONS
  Lignosulfonates did not require surfactants for their application; they did not burn the leaves, and had a stimulating effect on the vegetative growth of the plants. So these by-products could be a good alternative when applied through foliar sprays for cucumber plants.
authors.affiliation: Agricultural Chemistry Department, Universidad Autónoma de Madrid, Francisco Tomás y Valiente N° 7, 28049 Madrid, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Rodríguez-Lucena
authors.forename: Ana
authors.initials: A
authors.lastname: Benedicto
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Lucena
authors.forename: José A
authors.initials: JA
authors.lastname: Rodríguez-Castrillón
authors.forename: Mariella
authors.initials: M
authors.lastname: Moldovan
authors.forename: J Ignacio
authors.initials: JI
authors.lastname: García Alonso
authors.forename: Lourdes
authors.initials: L
authors.lastname: Hernández-Apaolaza
mesh_terms: D018533:Biomass; D018553:Cucumis sativus / Q000187:drug effects* / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D005052:Eucalyptus / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D007502:Iron Chelating Agents / Q000737:chemistry / Q000494:pharmacology; D007503:Iron Isotopes; D008031:Lignin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D028222:Picea / Q000737:chemistry*; D010935:Plant Diseases; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology; D018515:Plant Leaves / Q000378:metabolism; D013194:Staining and Labeling
chemical_list: D007502:Iron Chelating Agents; D007503:Iron Isotopes; D010936:Plant Extracts; C001545:lignosulfuric acid; D008031:Lignin; D004492:Edetic Acid; D007501:Iron