Jack beans and vetiver grass growth on iron ore tailing sediments from the Doce River dam disaster in Brazil: plant growth regulator effects under different edaphic conditions

Abstract

After the greatest environmental disaster in the history of Brazil and the deposition of the iron ore tailings in alluvial regions, the process of revegetation for environmental recovery becomes essential. A greenhouse experiment was carried out to evaluate the biomass production and nutrient accumulation by jack bean (Canavalia ensiformis (L.) DC) and vetiver grass (Chrysopogon zizanioides (L.) Roberty) grown on iron ore tailings from alluvial regions under two edaphic conditions using plant growth regulators. Iron ore tailings were obtained for use as the substrate. Jack bean and vetiver plants were grown in two conditions, high water and nutrient availability and low water and nutrient availability, while using four doses (0, 0.25, 0.5, and 0.75 L ha−1) of plant growth regulators (kinetins, gibberellic acid, and indole-butyric acid) via leaf spray. The use of plant growth regulators increased the biomass production (74 and 30% of total dry mass in jack bean and vetiver grass, respectively) and the accumulation of nutrients in the shoot parts of the plants cultivated with greater water and nutritional availability. Under limiting conditions of water and nutritional availability, the jack bean with the highest dose of plant growth regulator had a greater potential for revegetation, biomass production, and inputs of nitrogen, while vetiver grass had a greater contribution in potassium bio-cycling in the areas affected by the tailings deposited in the alluvial regions of the Doce River. The performance of the jack bean stood out in the two edaphic conditions due to growth stimulations by plant growth regulators.