8 pages, 4 figures, 3 tables.
A trial to assess the effects of applying several Fe-containing formulations on Fe-deficient (chlorotic) peach leaves was carried out under field conditions. Solutions consisting of an Fe-containing compound (FeSO4·7H2O, Fe(III)–citrate, Fe(III)–EDTA, Fe(III)–DTPA or Fe(III)–IDHA) and one of five different surfactant treatments (no surfactant, an organo-silicon, an ethoxylated oil, a non-ionic alkyl polyglucoside and a household detergent) were applied to one half of the leaf via dipping, first at the beginning of the trial and then after 4 weeks. The re-greening of treated and untreated leaf areas was estimated with a SPAD apparatus, on a weekly basis, during 8 weeks. At the end of the experimental period, leaves were detached, and tissue Fe, N, P, K, Ca, Mg, Mn, Zn and Cu concentrations were determined in Fe-treated and untreated leaf areas. Treatment with Fe-containing solutions always resulted in leaf chlorophyll (Chl) increases, which however significantly depended on the Fe-source, the surfactant-type and the combination between both formulation components. Untreated leaf zones experienced a Chl increase only in some cases, and this depended on the type of surfactant used. Iron application significantly increased the Fe concentration of treated and untreated leaf areas, especially with some formulations. Foliar treatment with Fe-containing solutions induced significant changes in the concentration of several nutrients as compared to those found in Fe-deficient peach leaves, with changes being similar in treated and untreated leaf areas, although in some elements the extent of the changes was of a different magnitude in both materials. This indicates that some leaf mineral composition changes typical of chlorotic leaves are dependent on leaf Fe concentration rather than on leaf Chl levels. Results obtained are relevant to help understand the factors involved in the penetration and bioavailability of leaf-applied Fe, and to assess the potential of foliar Fe fertilization to control Fe deficiency in fruit trees.
Study supported by the Spanish Ministry of Science and Education (Projects AGL2004-0194 and AGL2006-01416, co-financed with FEDER), the European Commission (ISAFRUIT project, Thematic Priority 5-Food Quality and Safety of the 6th Framework RTD Programme, Contract no. FP6-FOOD-CT-2006-016279), and the Aragón Government (group A03). V. Fernández was on a CSIC “I3P” post-doctoral contract co-financed by the European Social Fund.
Peer reviewed