Tolerance and growth of brachiaria (Urochloa brizantha) associated with arbuscular mycorrhizal fungi to doses of zinc and nickel – perspective of decontamination of potentially toxic metals ZN (II) and NI (II) in agricultural soils

Resumo

The indiscriminate contamination of the environment by potentially toxic metals (MTPs) due to human action poses socioeconomic and environmental problems. Phytoremediation is a sustainable technique used for soil decontamination, using plants capable of absorbing and accumulating PTMs in their tissues. The present study aimed to evaluate the tolerance and development of Brachiaria (Urochloa brizantha) as a phytoremediator of the metals Nickel (Ni⁺²) and Zinc (Zn⁺²), through analysis of translocation factors (FT) and bioaccumulation (FBC), and to compare the phytoremediation potential in symbiosis with arbuscular mycorrhizal fungi (FMA). The study was conducted in a greenhouse, in a completely randomized design, with a 6x2x3 factorial system, with 6 doses of the metallic species incubated in the soil (0, 10, 20, 40, 60, and 80 mg kg^-1), with inoculation of FMA and absence, with 3 repetitions each, resulting in 36 experimental units. The determination of the percentage of organic matter (MO) was done via the volumetric method using potassium dichromate. Physicochemical parameters, height and chlorophyll index were determined. DTPA extracting solution was used to determine MTPs. The data were subjected to analysis of variance using the software AgroEstat and the means was compared using the Tukey test at 5 % probability. The MO concentration was 16,03 mg kg^-1, characterizing a soil that retains negative charges. Ni⁺² and Zn⁺² had FT <1, making Brachiaria a phytoextractor, while FBC presented results >1, making it a hyperaccumulator. Treatments with FMA were more efficient. The grass showed good development in contaminated soil at different MTPs dosages.