Effectiveness of different foliar iron applications to control iron chlorosis in orange trees grown on a calcareous soil

The effectiveness on controlling Fe chlorosis in orange trees grown on calcareous soils was tested. The treatments were Fe(II) sulfate (500 mg Fe L-1), sulfuric acid (0.5 mM H2SO4), Fe(III)-chelate (Hampiron 654 GS, 120 mg Fe L-1) and distilled water as a control. A non-ionic wetting agent was used in all treatments. The use of frequent foliar sprays alleviated Fe chlorosis in orange trees. Sprays of Fe(II) sulfate increased the concentrations of chlorophyll, Fe and zinc in leaves and improved fruit size and quality compared to fruits of control trees. Sprays of Fe(III)-chelate also increased leaf chlorophyll and Fe concentrations and improved fruit quality, but did not increase fruit size. Sprays of sulfuric acid alone slightly increased leaf chlorophyll and Fe concentrations, without improving fruit size and quality. These results suggest that foliar sprays with Fe could help to avoid yield and quality losses caused by Fe chlorosis in citrus orchards. Furthermore, these treatments could be done with relatively cheap materials such as solutions containing Fe(II) sulfate.