Univariate and multivariate analysis on the ecotoxicological effects of chromium on Parkia pendula (willd.) Walp. Seed germination

Abstract

The presence of heavy metals in the Amazon has been growing since the last century, due to anthropic exploitation in areas where water and forest resources are located, in which the most common activity is mining. Visgueiro (Parkia pendula), a forest species from the Brazilian Amazon, can be useful for the recovery of degraded areas, and be used as a phytoremediation plant. Therefore, it was up to this study to carry out univariate (quantitative and qualitative) and multivariate (PCA) analyzes to evaluate germination rates of the Parkia pendula species subjected to increasing concentrations of chromium, due to this plant being little known about its phytoremediation potential. The work was carried out in a growth room, at a constant temperature of 30°C with a photoperiod of 12 hours, conducted in a completely randomized design (DIC), with five treatments, namely through the aqueous solution of chromium chloride III (CrCl3.6H2O ), made at concentrations corresponding to 0 mM (control), 2.5 mM, 5 mM, 7.5 mM and 10 mM. The percentage of seed germination was 96% in the seeds without contact with the metal, and when chromium is applied this percentage reduces to 73.6%, a possible explanation for this fact is that chromium acts in the enzymatic metabolism blocking the growth of the embryonic axis. The higher the chromium dosage, the lower the CVG, IVG and amount of viable seeds, and the higher the TMG and non-viable seeds, such factors may be due to the stimulus of CrCl3.6H2O under the blockade of the synthesis of hydrolytic enzymes, reducing sugars important for seed germination and viability. In the multivariate analysis of principal components, data variability is explained by 89.2% in dimension 1 and 8.3% in dimension 2, totaling 97.5% of the total data variability, with low contribution from germination percentage and high contribution of the TMG, CVG and IVG indices. The application of chromium concentrations in Parkia pendula seeds impairs the germination process of the species, and the treatment with 10 mM is more harmful for the germination percentage.