Effect of Cadmium Stress on Growth and Electrical Impedance Spectroscopy Parameters of Cotinus coggygria Roots
The use of plants for ecological remediation is an important method of controlling heavy metals in polluted land. Cotinus coggygria is a landscape plant that is used extensively in landscaping and afforestation. In this study, the cadmium tolerance level of C. coggygria was evaluated using electrical impedance spectroscopy (EIS) to lay a theoretical foundation for broad applications of this species in Cd-polluted areas and provide theoretical support to broaden the application range of the EIS technique. Two-year-old potted seedlings of C. coggygria were placed in a greenhouse to analyse the changes in the growth, water content and EIS parameters of the roots following treatment with different Cd concentrations (50, 100, 200, 500, 1000 and 1500 mg kg−1), and soil without added Cd was used as the control. The roots grew well following Cd treatments of 50 and 100 mg kg−1. The Cd contents increased with the increase in Cd concentration in the soil. However, the lowest root Cd content was found at 4 months of treatment. The extracellular resistance re and the intracellular resistance ri increased first overall and then decreased with the increasing Cd concentration, and both parameters increased with a longer treatment duration. The water content had a significant negative correlation with the Cd content (P < 0.01) and the re (P < 0.05). C. coggygria could tolerate a soil Cd concentration of 100 mg kg−1. There was a turning point in the growth, water content and EIS parameters of the C. coggygria roots when the soil Cd concentration reached 200 mg kg−1. The root water content and re could reflect the level of Cd tolerance in C. coggygria.
KeywordsHeavy metals Root system Cd content; water content Specific extracellular resistance
We thank Bingxiang Liu for technical support. Tiangang Fan and Zhen Li and Hongxiao Li provided useful help with seedling cultivation.
GZ designed and conducted the experiment; DYX conducted the experiment, measured and calculated the EIS, analysed the data and discussed the results; RJG measured the Cd content; BD measured the water content. DYX and GZ wrote the paper, and GZ is the corresponding author; RJG, BD and YRT participated in manuscript preparation. All authors have read and approved the final manuscript.
We thank the Department of Science and Technology of Hebei for funding this research (Grant number C2011204107).
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