Growth of cumaru (Amburana cearensis) seedlings irrigated with industrial effluent.

In view of the need to implement programs to recompose vegetation cover, urban afforestation, charcoal production, firewood production, and other wood or non-wood purposes, it is necessary to use alternatives and techniques that facilitate the production of seedlings in order to meet these demands, where water reuse is a promising alternative to ensure production at a reduced cost, without compromising the use of drinking water, without generating waste, potentiating the production process and promoting social and environmental benefits. Thus, it is necessary to adopt strategies to improve the efficiency of wastewater reuse for the production of forest species seedlings without compromising the initial growth of species. In this sense, the objective of this work was to evaluate the growth of Amburana cearensis plants in different substrates irrigated with industrial effluent. The study was conducted in a greenhouse in the city of Mossoró, state of Rio Grande do Norte. The experimental design was randomized blocks in a 2 × 5 factorial scheme, corresponding to two substrates and five effluent doses (0%, 25%, 50%, 75%, and 100%). The substrates used were soil with organic compost (S1) and soil with water hyacinth fiber (S2). Growth was evaluated by stem diameter (DC) and seedling height (H). Evaluations were performed every 15 days for 3 months. Absolute growth rate (AGR) and relative growth rate (RGR) were determined. Regression and correlation analysis was also performed. We found that the average stem diameter was larger for plants grown in the substrate with water hyacinth fibers (S2) and the average height was higher in the substrate with organic compost (S1). The RGR showed the same behavioral pattern in the control treatment at doses 25 and 50% in S1. In S2, the RGR for stem diameter decreased continuously with rising doses. The relative growth rates for height showed a tendency to decrease independently of treatments. Therefore, the seedlings showed good growth characteristics for all treatments and the 50% dose in S1 achieved the best results.