Uso de espécies arbóreas e arbustivas na fitorremediação de 2,4-D e oxyfluorfen

Abstract

Phytoremediation has emerged as a viable alternative for restoring areas impacted by toxic compounds, including herbicides. A major constraint to this technique is the selection of species capable of herbicide phytoremediation. The objectives of this study were: 1 - to evaluate the tolerance of ten native and exotic tree species to the herbicides 2,4-D and oxyfluorfen, in order to select those with greater potential for phytoremediation of contaminated areas; 2 - to assess the tolerance of Cajanus cajan, Moringa oleifera, and Schizolobium parahyba var. amazonicum to different doses of 2,4-D and oxyfluorfen. The preliminary study for species selection was conducted in a completely randomized design, in a 2 × 10 factorial scheme, with four replications, consisting of two herbicides (2,4-D and oxyfluorfen) combined with ten tree species. The tree species tested were: Albizia niopoides, Anadenanthera peregrina, Cajanus cajan, Handroanthus impetiginosus, Leucaena leucocephala, Moringa oleifera, Peltophorum dubium, Prosopis juliflora, Schizolobium parahyba var. amazonicum, and Tithonia diversifolia. The recommended label dose of the herbicides was applied 28 days before sowing the tree species, and seedling emergence and early growth were evaluated 60 days after sowing. The species C. cajan, M. oleifera, and S. parahyba showed greater tolerance to both 2,4-D and oxyfluorfen. Based on these selected species, two independent experiments were conducted, each using one herbicide. The experiments were arranged in a 3 × 5 factorial scheme, with three tree species (C. cajan, M. oleifera, and S. parahyba) combined with different levels of soil herbicide contamination (0%, 25%, 50%, 75%, and 100% of the recommended label dose). S. parahyba maintained physiological activity even at the highest oxyfluorfen doses, emerging as the most promising species for the phytoremediation of this compound. M. oleifera was highly sensitive to oxyfluorfen, whereas C. cajan showed tolerance with low phytointoxication and signs of adaptation. Conversely, C. cajan was highly sensitive to 2,4-D, exhibiting severe symptoms that led to plant death shortly after emergence. M. oleifera showed moderate effects but demonstrated physiological recovery over time. For areas contaminated with oxyfluorfen or 2,4-D, the use of S. parahyba and M. oleifera, respectively, is recommended. These results support the potential of phytoremediation using forest species for the decontamination of herbicide-impacted soils.