Evaluating phytoremediation potential of various weeds in cadmium-contaminated soil

Cadmium (Cd) is one of the most toxic and prevalent heavy metal environmental contaminant. As weeds are more resistant to abiotic stress, certain weed species are hypothesized to possess strong potential for phytoremediation. Thus, a pot experiment was conducted to evaluate the phytoremediation potential of wild oat, little seed canary grass, swinecress, toothed burclover, and nettle-leaved goose foot under varying concentrations of Cd (control, 100 and 200 mg/kg). All weeds could sustain higher concentrations, but exposure to 200 mg/kg Cd decreased shoot dry weight by 31-70% for all weeds. At 100 mg/kg Cd, all weeds showed enhanced antioxidant activity, whereas at 200 mg/kg Cd, antioxidant activity decreased. Increasing Cd stress also led to reductions in internal CO₂ concentration, photosynthetic rate, stomatal conductance, and transpiration rate in all studied weeds. The highest cadmium concentrations were found in wild oats and little seed canary grass. The bioaccumulation factor analysis revealed that wild oat and little-seeded canary grass were Cd accumulators. Translocation factor values revealed that all weeds, except little seed canary grass, accumulated more Cd in their shoots than their roots. These findings suggest that the selected weed species can tolerate cadmium stress, with wild oat and little seed canary grass showing promising potential for use in Cd phytoremediation efforts.