Foliar treatment of Mn deficient 'Washington navel' orange trees with two Mn sources

The objective of this study was the comparison of the effect of two Mn sources (MnSO4-H2O, MnEDTA) which were applied at various concentrations (0, 200, 400, 800, and 1200 mg Mn l(-1)) to the leaves of 'Washington navel' orange trees in order to correct Mn deficiency. One hundred and seventy days after the foliar application of Mn solutions, the mean Mn concentrations in the leaves treated with MnSO4-H2O (200, 400, 800 or 1200 mg Mn l(-1)) or MnEDTA (400, 800 or 1200 mg Mn l(-1)) were significantly higher than those of the control leaves. Manganese sulfate (MnSO4 center dot H2O) was more effective than MnEDTA regarding the improvement of the leaf Mn concentrations of the trees, when applied at equal Mn concentrations. Finally, the leaf Mn concentrations were in the sufficiency range (> 25 mg kg(-1) d.w.), only after the application of 800 or 1200 mg Mn l(-1) as MnSO4 center dot H2O. (c) 2005 Elsevier B.V. All rights reserved.