Native leguminous trees as natural solutions for herbicide‐polluted soils: evidence from Inga edulis

Abstract

The extensive use of 2,4‐dichlorophenoxyacetic acid (2,4‐D) in tropical agricultural and pasture systems has heightened concerns regarding soil contamination, nontarget plant injury, and risks to adjacent natural ecosystems. Identifying native species capable of both tolerating and mitigating herbicide residues is therefore essential for developing effective phytoremediation strategies. The objective of this study was to evaluate (i) the tolerance of Inga edulis , a fast‐growing nitrogen‐fixing tree, to environmentally relevant concentrations of 2,4‐D and (ii) its capacity to reduce residual herbicide toxicity in the soil. Two complementary greenhouse experiments were conducted. In the tolerance assay, I. edulis seedlings were cultivated for 90 days in a dystrophic Red‐Yellow Latosol amended with four levels of 2,4‐D residues (0, 0, 5, 1, and 2 mL L −1 ). Growth parameters—including height, stem diameter, canopy area, leaf production, and biomass—were quantified, along with visual intoxication scores. In the subsequent bioassay, the sensitive species Bidens pilosa was grown in soils previously cultivated with or without I. edulis to assess residual toxicity. Inga edulis exhibited mild foliar symptoms but no reductions in growth or biomass across residue levels, indicating strong tolerance. Soils previously cultivated with I. edulis consistently reduced intoxication and enhanced biomass of B. pilosa , demonstrating attenuation of 2,4‐D phytotoxicity. These results show that I. edulis can simultaneously withstand and mitigate 2,4‐D contamination.