Selected physiological responses of kudzu to different chromium concentrations

Abstract

This study was designed to evaluate the potential use of kudzu (Pueraria montana var. lobata) as a phytoremediator to reduce Cr (VI) contamination. In addition, the effect of Cr concentrations of 4, 8, and 12 mg L–1 on kudzu growth, gas exchange, pigment concentration, and carbohydrate accumulation were evaluated. In general, Cr uptake by kudzu was increased as Cr concentration increased in the growing media. Most of the Cr taken up by kudzu was accumulated in the root as indicated by the significantly higher ratio of root/shoot Cr concentrations at increasing Cr levels in the root environment. Kudzu growth, photosynthetic rate, and chlorophyll a and b concentrations declined as the Cr concentration increased. The decrease in photosynthesis was independent of the internal carbon dioxide. Anthocyanin was found to increase as Cr concentration gradually increased from 4 to 12 mg L–1. Kudzu clearly demonstrated its ability to survive at Cr concentrations up to 8 mg L–1 in the root environment. Kudzu, therefore, can be considered as a replacement crop in areas of Cr contamination falling within the concentration range of this study. Key words: Carbohydrate, chromium uptake, photosynthesis, phytoremediation