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Scientia Silvae Sinicae ›› 2016, Vol. 52 ›› Issue (5): 71-80.doi: 10.11707/j.1001-7488.20160509

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Variations in Lead Accumulation and Tolerance in Different Varieties of Salix integra and in Situ Distribution of Elements in Leaves under Pb Stress

Wang Shufeng1,3, Shi Xiang1,3, Tian Shengke2, Sun Haijing1,3, Yang Xiao2, Chen Yitai1, Liu Ting2   

  1. 1. Research Institute of Subtropical Forestry, Chinese Academy of Forestry Fuyang 311400;
    2. College of Environmental and Resource Sciences, Zhejiang University(Zijingang Campus) Hangzhou 310058;
    3. Key Laboratory of Tree Breeding of Zhejiang Province Fuyang 311400
  • Received:2015-04-16 Revised:2015-12-10 Online:2016-05-25 Published:2016-06-01

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Abstract:

[Objective] This study aimed to evaluate phytoremediation potential of different Salix integra varieties in the remediation of lead contaminated soils and to provide information for clarifying the Pb toxicity to willow trees. [Method] To investigate the variation of Pb tolerance and accumulation in S. integra, ahydroponic experiment with three cultivated varieties of S. integra including Weishanhu, Yizhibi and Dahongtou was conducted and the seedlings were treated with three Pb concentrations (CK: 0 μmol·L-1, T1: 100 μmol·L-1, T2: 200 μmol·L-1). [Result] Compared to the control, the height growth and biomass accumulation of seedlingsof all three varieties subjected to Pb treatments were inhibited significantly (P<0.05). The seedling height growth showed a significant decrease with the increase of Pb concentration, whereas no significant changes were observed in the dry weight of the aboveground parts and the root with 100 μmol·L-1 and 200 μmol·L-1 of Pb treatments. The Pb tolerance of the three varieties differed depending on the Pb concentration and the Pb accumulation varied in different organs. All three varieties showed high tolerance index (TI) under both Pb treatments, of which Weishanhu exhibited the highest TI, followed by Yizhibi, and Dahongtou had the lowest TI. The accumulation of Pb in different tissues was from high to low: root > stem > twig > leaf. Based on the calculation of translocation factor (TF) for the aboveground tissues, an extremely low TF was found in wood, new shoots and leaves, indicating that Pb sequestration was mainly restricted in roots. The aboveground Pb was mainly reserved in stem. In this study, Pb and other mineral elements distribution in leaf tissues were also investigated by synchrotron radiation X-ray fluorescence analysis. The results indicated that Pb concentrations were detected in the middle vein of leaves, which was similar to the distribution of other ions, such as Zn and K. According to Pearson correlation analysis, the accumulation of Pb in leaves was positively related with K, Zn, Ca and Fe, indicating the translocation of Pb in leaves may be related to the uptake of these ions. [Conclusion] S. integra can tolerate and accumulate high levels of Pb in the root when exposed to different Pb concentrations, and there is no significant difference in the tolerance to Pb among the three varieties. However, as a good candidates for phytoremediation, Weishanhu exhibits better growth and biomass accumulation than the other two varieties, thus could be recommended for phytostablization of Pb in contaminated areas.

Key words: Salix integra, lead, tolerance and accumulation, synchrotron radiation X-ray fluorescence

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