Utilization of kudzu as a lead phytoremediator and the impact of lead on selected physiological responses

Abstract

Schwarzauer-Rockett, K., Al-Hamdani, S. H., Rayburn, J. R. and Mwebi, N. O. 2013. Utilization of kudzu as a lead phytoremediator and the impact of lead on selected physiological responses. Can. J. Plant Sci. 93: 951–959. This study was carried out to evaluate kudzu [Pueraria montana var. lobata (Willd.)] in lead phytoremediation. The impact of lead (PbNO3) concentrations of 100 and 200 mg L−1 on plant growth, photosynthetic pigments, photosynthesis, and stomatal conductance were evaluated. Additionally, concentrations of phenolic compounds and anthocyanin were determined. The lead was dissolved in 0.142 g L−1 ethylenediaminetetraacetic acid (EDTA) and an EDTA control treatment was added to evaluate the impact of EDTA on the above selected plant responses. Root accumulation of lead was significantly higher than in the shoot. Kudzu growth in response to the presence of lead and EDTA in the Hoagland's solution was similar to that of the EDTA control, except for plants growing at 200 mg L−1, which showed significantly lower root dry weight. Total phenolic compounds increased with the presence of EDTA and lead in the Hoagland's solution. Photosynthetic rate, stomatal conductance, chlorophyll a and chlorophyll b, carotenoids, and anthocyanin were not different (P≤0.05) among the treatments, with the exception that carotenoids were significantly higher in plants growing in the presence of EDTA without lead compared with 200 mg L−1 lead concentration. Kudzu accumulated most of the lead in the root and therefore can be considered as a rhizofiltrator. As kudzu was able to accumulate 1.02% (wt/wt) of lead it can be considered a hyper-accumulator.