Foliar application of manganese sources on glyphosate-resistant soybean in no-tillage

Abstract

The glyphosate herbicide when applied in post-emergence in transgenic soybean can influence manganese (Mn) nutrition, with differentiated response when parceled out. The objective of this study was to evaluate the soybean response to Mn sources applied via leaf, in different phenological stages. Two experiments were carried out in areas with different Mn contents in the soil, using four Mn sources, sulphate and nitrate (experiment A), phosphite and Mn-EDTA (experiment B). Leaf application of Mn was done at V8 and V12 (150+150 g ha-1), V8 (single application at 300 g ha-1) and V12 (single application at 300 g ha-1). In experiment A, the plants treated with nitrate, in split application, had greater leaf area and height of insertion of the first pod. The nitric source resulted in higher soybean yield when applied at V12. On the other hand, sulphate provided plants with higher height at harvest and higher yield with split application. In experiment B, it was found a larger leaf area with application of Mn-EDTA in V12. The application of phosphite provided higher at harvest height when applied in V8 and higher leaf Mn content when applied in V12. The insertion of the first pod was lower in plants treated in V12 with phosphite or with Mn-EDTA and V8. The Mn-EDTA source resulted in higher yield of transgenic soybeans at a dose of 300 g ha-1, applied at V8 or V12, in no-till area with low Mn content in the soil.