Initial growth of Peltophorum dubium is affected by nitrogen source and manganese concentration

Abstract

This study investigated the interaction between different inorganic sources of nitrogen and concentrations of manganese during the initial development of Peltophorum dubium, a tree native species from Atlantic Forest (Brazil), in order to determine the best nitrogen source to be used in revegetation of the area affected by iron ore tailings from Fundão dam rupture. Plants were grown in three different sources of nitrogen (4 mM ammonium, 3mM nitrate + 1mM ammonium and 4 mM nitrate) and three concentrations of manganese (0.5, 25, and 50 mg L−1). Growth measurements, chlorophyll a fluorescence, and plant nutritional status were performed and oxidative stress markers were assessed after 80 days. Application of 25 mg Mn L−1, similar to the concentrations found in the tailings, did not affect the initial growth of P. dubium plants when nitrate was used as a sole source of nitrogen. On the other hand, ammoniacal fertilization, especially when combined with 50 mg Mn L−1, caused acidification of the substrate, less accumulation of total biomass, and alteration to dry mass partitioning between the shoot and the root, in addition to an imbalance of mineral elements in root and shoot. A higher Mn translocation index and reduced potential quantum yield of chlorophyll a were also observed when the plants were grown in the presence of ammonium. The growth of P. dubium is not compromised by the concentrations of Mn present in the tailings and the species is strongly indicated for the restoration of the affected area, especially using nitrate as the sole source of nitrogen.