Silicon uptake and transport is an active process in Cucumis sativus

Authors

  • Yongchao Liang,

    Corresponding author
    1. Institute of Soil and Fertilizer, and Ministry of Agriculture Key Laboratory of Plant Nutrition and Nutrient Cycling, Chinese Academy of Agricultural Sciences, Beijing 100081, China;
    2. Institute of Plant Nutrition (330), University Hohenheim, D-70593 Stuttgart, Germany;
    • Author for correspondence: Yongchao Liang Tel: +86 10 68918657 Fax: +86 10 68975161 Email: ycliang@caas.net.cn

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  • Jin Si,

    1. Institute of Plant Nutrition (330), University Hohenheim, D-70593 Stuttgart, Germany;
    2. Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
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  • Volker Römheld

    1. Institute of Plant Nutrition (330), University Hohenheim, D-70593 Stuttgart, Germany;
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Summary

  • •  Cucumis sativus is a species known to accumulate high levels of silicon (Si) in the tops, though the mechanism for its high Si uptake is little understood. In a series of hydroponic experiments, we examined uptake and xylem loading of Si in C. sativus along with Vicia faba at three levels of Si (0.085, 0.17 and 1.70 mm).
  • • Measured Si uptake in C. sativus was more than twice as high as calculated from the rate of transpiration assuming no discrimination between silicic acid and water in uptake. Measured Si uptake in V. faba, however, was significantly lower than the calculated uptake. Concentration of Si in xylem exudates was several-fold higher in C. sativus, but was significantly lower in V. faba compared with the Si concentration in external solutions, regardless of Si levels.
  • • Silicon uptake was strongly inhibited by low temperature and 2,4-dinitrophenol, a metabolic inhibitor, in C. sativus but not in V. faba.
  • • It can be concluded that Si uptake and transport in C. sativus is active and independent of external Si concentrations, in contrast to the process in V. faba.

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