Assessment of herbaceous ornamental plant species as potential remediation agents for cadmium contaminated environments

Industrial development has led to the pollution of lands with Cadmium (Cd), resulting in the contamination of edible crops and posing significant health risks to humans and animals. To address this issue, the selection of non-edible ornamental plants has been considered. In this study, a lab-scale experiment was conducted using five different ornamental plant species: Tabermaeontana divaricata L., Syngonium podophyllum Schott, Asparagus setaceus (Kunth) Jessop, Catharanthus roseus (L.) G. Don. and Portulaca grandiflora Hook. These plant species were treated 100 mL of 5 mg L-1 CdSO4 solution, continuing for 30 days in hydroponic medium with replenishment with same solution on every 3rd day. The main objective was to identify ornamental plant species with high tolerance and remarkable Cd translocation and accumulation power. The plants were evaluated based on their Tolerance Index (TI), Translocation factor (TF) and Bioaccumulation Factor (BAF) toward Cd in the hydroponic medium. P. grandiflora exhibited high tolerance to Cd with 95 % TI and S. podophyllum (TI - 85 %) and T. divaricata (TI - 62 %) showed limited tolerance while C. roseus and A. setaceus were found to be more sensitive. Moreover, Cd presence was also found to induce a hormetic response in P. grandiflora, T. divaricata, and S. podophyllum. Based on their TF and BAF values, P. grandiflora (TF-5.45; BAF-0.86) and S. podophyllum (TF-4.49; BAF-0.85) were identified as potential candidates for phytoextraction, while T. divaricata (TF-0.007; BAF-4.34) showed potential as a phytostabilizer of Cd. These findings propose for the utilization of these ornamental plants for the remediation of the Cd-contaminated soil and water, with the harvested biomass potentially serving as bio-ore for recovery of Cd.