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Acta Prataculturae Sinica ›› 2017, Vol. 26 ›› Issue (5): 109-117.DOI: 10.11686/cyxb2016419

• Orignal Article • Previous Articles     Next Articles

Effects of cutting frequency on cadmium uptake and physiological responses of Medicago sativa under cadmium stress

LI Na1, SUN Ning-Xiao1, SONG Gui-Long1, *, PUYANG Xue-Hua2, ZHOU Shu-Qiong2, ZHAO Ke-Qi2, JIANG Kai2   

  1. 1.Institute of Turfgrass Science, Beijing Forestry University, Beijing 100083, China;
    2.Shenzhen Techand Ecology & Environment Co., Ltd, Shenzhen 518040, China;
  • Received:2016-11-07 Revised:2016-12-29 Online:2017-05-20 Published:2017-05-20

Abstract: Alfalfa (Medicago sativa) is a promising plant species for phytoremediation in soils polluted by heavy metals. This species has been reported to have a high growth rate and great potential for cadmium (Cd) accumulation. Alfalfa plants must be cut several times to reduce soil Cd concentrations to acceptable levels. Therefore, the aim of this study was to evaluate the effects of one, two, and three cuttings on the growth, Cd content, and physiological characteristics of alfalfa plants grown in Cd-contaminated soil. Alfalfa plants were grown in soil containing no Cd (control) and Cd at three concentrations (10, 25, 50 mg/kg) and cut once, twice, or three times. A higher number of cutting events promoted the growth rate and biomass accumulation in the shoot. The highest average shoot growth rate was 61.6 mg/(plant·d) in the three-cuttings treatment, but root growth was significantly lower in this treatment (P<0.05) than in the other treatments and the control. Over the whole growth cycle, cutting twice or three times improved the Cd uptake rate in the root and Cd accumulation in the shoot, thus increasing Cd enrichment in alfalfa plants. The highest Cd accumulation was 75.98 μg/plant in the 25 mg/kg Cd treatment with two cuttings. The relative electrical conductivity and malondialdehyde (MDA) contents were lower in the two-cuttings and three-cuttings treatments than in the single cutting treatment, but the proline contents were higher, which improved the tolerance of alfalfa to Cd toxicity under Cd stress. We concluded that in soil containing Cd at ≤ 25 mg/kg, two cuttings can significantly improve the repair efficiency of alfalfa plants growing in Cd-polluted soil.

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