Weed Species Associated with Cacao Cultivation Exhibiting Phytoremediation Potential for Cadmium and Lead: A Study Based on Bioconcentration and Translocation Factors

Abstract

The exploration and identification of spontaneous weed species in heavy metal–contaminated soils represent a relevant approach for understanding the role and their potential application in phytoremediation. In cacao cultivation, cadmium contamination poses a significant risk due to the restrictions established for soils and cacao-derived products, thereby threatening productive sustainability and export viability. The objective of this study was to identify weed species associated with cacao cultivation exhibiting accumulation patterns and phytoremediation potential for Cd and Pb, through the assessment of biomass production and the bioconcentration factor (BCF) and translocation factor (TF), in natural conditions. Soil samples were collected from seven cacao-growing zones, and the site with the highest Cd concentration (1.65 mg kg−1) was selected, where ten dominant weed species were identified and evaluated. Significant interspecific differences were observed in biomass production and in Cd and Pb concentrations (p < 0.05). Talinum paniculatum exhibited the highest total biomass (6.15 g) and the highest TF for Cd, whereas Cyperus aggregatus showed the greatest total Cd accumulation (2.68 mg kg−1). BCF and TF values enabled the identification of species with accumulation patterns consistent with Cd phytoextraction (T. paniculatum, C. aggregatus, Pseudelephantopus spiralis, Bidens riparia, Euphorbia heterophylla, and Malvastrum coromandelianum) and with phytostabilization (Ocimum campechianum). For Pb the observed patterns were consistent with potential phytoextractive behavior in B. riparia, P. spiralis, E. heterophylla, Hilleria latifolia, and Acalypha stachyura. Although these results do not constitute functional evidence of remediation, they describe heavy metal accumulation and translocation patterns in native weed species, providing a technical basis for the design of future experimental trials aimed at the sustainable remediation of contaminated soils.