Interspecific differences in growth response and tolerance to the antibiotic sulfadiazine in ten clonal wetland plants in South China.

Pollution caused by residual antibiotics is a worldwide environmental issue. Antibiotic residues often occur in aquatic ecosystems, posing threats to the health of aquatic organisms. The effects of antibiotic residues on the growth of crop plants and on human health are reasonably well known. However, less is known about antibiotic effects on wetland plants. Therefore, we studied the response and tolerance of ten clonal wetland plants grown in soil spiked with sulfadiazine at 10 mg kg(-1) (an environmentally relevant concentration) and 100 mg kg(-1). At 10 mg kg(-1), ramet number was the least affected trait, while root number was the most affected among plant species. Plant shoot and total biomass were reduced in all species except in Cyperus malaccensis var. brevifolius and Panicum repens. Chlorophyll content was reduced in Alocasia macrorrhiza, Saururus chinensis, and Commelina diffusa. In general, Panicum paludosum and C. malaccensis var. brevifolius showed the least reduction of growth parameters, whereas growth of both A. macrorrhiza and S. chinensis was severely reduced. At 100 mg kg(-1), negative responses occurred in all species. Comprehensive tolerance analysis revealed that P. paludosum and C. malaccensis var. brevifolius were the species most resistant to sulfadiazine. These species are potential candidates for sulfadiazine polluted wetland restoration. A. macrorrhiza and S. chinensis were the most susceptible species and they should be protected from sulfadiazine pollution. Relative plant shoot biomass and height were the most useful indicators for evaluating plant tolerance to sulfadiazine. Plant tolerance to sulfadiazine was associated with the differences of plants in height and shoot biomass.