Fertilizer Management 606A gronomy J our n al • Volu me 102 , I s sue 2 • 2 010 ABSTRACT Glyphosate-resistant (GR) soybean [Glycine max (L.) Merr.] is widely produced and provides many benefi ts to production agriculture, however, recent reports suggest that GR soybean genetics may result in reduced Mn uptake and increased response to Mn fertilization. Th e objective of this research was to determine response of GR and conventional (CV) soybean near-isolines to Mn fertilization. Th e soybean near-isoline pair KS4202 and K4202RR was planted at three locations and near-isoline pair KS4602N and KS4602NRR was planted at two locations in a split-block fi eld study. Manganese treatments consisted of soil-applied MnSO 4 at 0, 2.8, 5.6, and 8.4 kg Mn ha -1 and foliar applied Mn-glucoheptonate at 0.22 and 0.45 kg Mn ha -1 . Leaf tissue was analyzed for Mn at R1, R3, and R6 growth stages and seed was analyzed for Mn at harvest. Manganese concentrations in leaf tissue were above the critical value and were not aff ected by GR genetics at any location or growth stage. However, there were yield responses to Mn applications at three of the fi ve locations. KS4202RR soybean yield increased by 800 and 275 kg ha -1 with increasing Mn application rate at two locations when the near-isoline KS4202 yield did not increase. In contrast, at the third responsive location KS4602NRR did not respond to Mn application when the near-isoline KS4602N yield increased by 450 kg ha -1 . Th ese results indicate that although soybean response to Mn is infl uenced by genetics, neither the Mn uptake nor the Mn responsiveness were conclusively aff ected by glyphosate-resistance in soybean.