The severe deficiency of
iron or ferric
chlorosis is a serious problem of most citrus trees established in calcareous
soils, as a result of the low availability of
iron in these
soils and the poor uptake and limited transport of this nutrient in trees. The objective of this study was to evaluate the response of chlorotic Italian lemon trees (Citrus lemon) to the application of
iron compounds to roots and stems. On comparing the effects of aqueous solutions of
ferric citrate,
ferrous sulphate and FeEDDHA chelate, applied to 20% of the roots grown in soil and
sand, of trees that were planted in pots containing calcareous soil, it was observed that the chelate fully corrected ferric
chlorosis, while
citrate and sulphate did not solve the problem.
EDDHA induced the root uptake of
iron as well as the movement of the nutrient up to the leaves. With the use of
injections of ferric solutions into the secondary stem of adult trees,
ferric citrate corrected
chlorosis but
ferrous sulphate did not. The
citrate ion expanded the mobility of
iron within the plant, from the injection points up to the leaves, whereas the sulphate ion did not sufficiently improve the movement of
iron towards the leaf mesophyll.