Physiological potential of Swietenia macrophylla seeds and plants in heavy metal contamination for use in phytorremediation as a clean technology

Environmental contamination by heavy metals represents a growing concern throughout the world, and the physiological potential of the seed allows estimating the theoretical capacity to manifest its vital functions in stressful situations. Due to this, this work aimed to evaluate the effect of increasing dosages of nickel on the physiological potential of Brazilian mahogany (Swietenia macrophylla) seeds and seedlings, seeking to indicate the potential use of this species in phytoremediation programs for use as technology clean. The seeds were grown in polyethylene pots containing sand and maintained at a constant temperature of 28°C, relative humidity (RH) of 90% and a 12-hour photoperiod for 43 days. The experimental design used was randomized blocks, with five treatments (0, 2, 4, 6 and 8 mg.L-1 de NiCl2.6H2O), with six replications. Data were subjected to analysis of variance (ANOVA) and means were tested for significant differences by Tukey test using R-Studio-1.3.1093 software at 5% significance. Changes in plant growth and biomass were observed under different nickel concentrations. In stressful situations, seedling emergence decreased to 28.6%, the average emergence time was postponed to 25 days and there was a longer interval between the first and last seedling emergence, impacting stand establishment. Despite the variations, the seed was capable of emerging, developing and surviving environments contaminated by nickel, indicating some resistance to metal stress.