Efficiency of foliar application of sparingly soluble sources of boron and zinc in citrus

This study evaluated leaf supply of zinc (Zn) and boron (B) using either soluble or sparingly fertilizers in young sweet orange trees. Three experiments were set up a greenhouse to compare two sources four doses (control, low, adequate high) as follows: (i) Experiment I (B): boric acid calcium borate; (ii) II (Zn): Zn sulfate oxide; (iii) III (B + Zn): Sulfate Borate. The effective increasing the B concentration. Dry matter aerial part increased 18 % with applications concentration independent fertilizer sources. In contrast, trees did not grow well high borate. Superoxide dismutase activity leaves low oxide decreased from source. Polyphenol oxidase application Furthermore, upper concentrations toxic when source was sulfate. Increases plant growth without damage tissue positive responses key enzymes range nutrient demonstrated practical use supplying foliarily plants.