Fig. 5. Effect of increasing amounts of goethite application to the artificial substrate (G-0 = 0 g kg^–1; G-1 = 1 g kg^–1; G-4 = 4 g kg^–1) on the concentration of arsenic (As) in different organs of Zea mays 32 d after planting. A different scale had to be selected for concentrations in the roots. Means for the different treatments were separated by Tukey test. For each plant organ, means followed by the same letter were not significantly different from each other.