Evaluation of the phytoremediation potential of ornamental plants in lead (Pb)-contaminated soil

The Pb contamination in soil poses significant environmental and public health risks due to its non-biodegradable and bioaccumulative nature. This study evaluates the phytoremediation potential of six ornamental plant species-<i>Helianthus annuus</i>, <i>Gaillardia grandiflora</i>, <i>Brassica juncea</i>, <i>Euphorbia tithymaloides</i>, <i>Tradescantia pallida</i>, and <i>Canna indica</i>-for remediating Pb-contaminated soils. These species were selected for their short life cycles, adaptability, and tolerance to Pb stress. Pot experiments were conducted with soil spiked at Pb concentrations of 0, 20, 40, 80, and 160 mg kg^-1, and plant growth responses, Pb accumulation, and phytoremediation efficiency were assessed over 120 days. Growth parameters, including plant measurements (root and shoot length) and biomass, were recorded, alongside Pb concentrations in plant tissues. Phytoremediation efficiency was evaluated through bio-concentration factor (BCF), translocation factor (TF), and tolerance index (TI). Results showed that <i>C. indica</i>, <i>B. juncea</i>, <i>G. grandiflora</i>, and <i>H. annuus</i> exhibited enhanced or stable growth under Pb stress, while <i>T. pallida</i> was highly sensitive, showing significant growth reductions. <i>T. pallida</i> and <i>G. grandiflora</i> demonstrated the highest Pb accumulation, with <i>G. grandiflora</i> indicating phytoextraction potential (TF > 1). All species had BCF_root values > 1, indicating effective Pb uptake, particularly in roots. These findings suggest that the tested ornamental plants, especially <i>G. grandiflora</i> and <i>C. indica</i>, are promising candidates for phytoremediation of moderately Pb-contaminated soils, offering both environmental and esthetic benefits.