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| Effects of Ca/Mg ratios on growth and heavy metal uptake of three hyperaccumulators |
| Received:July 31, 2015 |
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| KeyWord:Ca/Mg ratio;hyperaccumulator;zinc;nickel;cadmium;lead |
| Author Name | Affiliation | E-mail | | ZHAO Tao | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | LIU Deng-biao | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
Shenzhen Techand Ecology & Environment Co. LTD, Shenzhen 518000, China | | | ZHENG Jun-yu | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | JIANG Cheng-ai | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
Key Laboratory of Soil Environment and Waste Reuse in Agriculture of Guangdong Higher Education Institutes, Guangzhou 510642, China | chaijiang@scau.edu.cn |
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| Abstract: |
| Enhancing biomass and heavy metal uptake of hyperaccumulators would improve soil phytoremediation efficiencies. In this study, we investigated the effects of Ca/Mg ratios(0.2, 0.5, 1.0, 2.0, 4.0, and 6.0) on growth and metal uptake by Sedum alfredii(Zn and Cd hyperaccumulator), Noccaea caerulescens(Zn, Cd and Ni hyperaccumulator) and Alyssum murale(Ni hyperaccumulator) under hydroponic system spiked with 20 mg Zn·L-1, 18 mg Ni·L-1, 10 mg Pb·L-1 and 0.5 mg Cd·L-1. Results indicated that significant high transfer coefficient of Ca(TF, 5.98~11.19) from roots to shoots and Ca/Mg ratio in shoots(2.45~16.74) were found in A. murale. The TF of Mg(1.43~3.70) was higher than that of Ca(0.77~1.38) for N. caerulescens, while TF of Mg(1.24~1.45) was similar to that of Ca(0.88~1.66) for S. alfredii. For N. caerulescens, the greatest growth and Zn/Cd/Ni accumulation of shoots was obtained in normal nutrient solution(Ca/Mg 2.0), but plant growth and metal accumulation were restrained under increased Ca or Mg supply. For A. murale, the highest biomass and Ni accumulation of shoots was observed at the highest Ca/Mg ratio(Ca/Mg 6.0). Increasing Ca supply promoted but increasing Mg supply decreased Ni accumulation in the shoots. For S. alfredii, Zn accumulation in shoots and roots increased with increasing Ca supply, and Cd concentration in roots increased with Ca or Mg supply, but the best growth and the highest Zn and Cd concentrations in shoots were observed at the lowest Ca/Mg ratio(Ca/Mg 0.2). Our results suggest that the effect of Ca/Mg ratio on hyperaccumulators depends on both plant and metal species. |
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