Microbial activities and foliar uptake of nitrogen in the epiphytic bromeliad Vriesea gigantea

Authors

  • Erich Inselsbacher,

    1. Department of Chemical Ecology and Ecosystem Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria;
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  • Camila Aguetoni Cambui,

    1. Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, C.P. 11461, São Paulo, SP 05422-970, Brazil;
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  • Andreas Richter,

    1. Department of Chemical Ecology and Ecosystem Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria;
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  • Claus Florian Stange,

    1. Institute of Soil Science and Plant Nutrition, UFZ Centre for Environmental Research, Martin-Luther-University Halle-Wittenberg, Weidenplan 14, 06120 Halle/Saale, Germany
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  • Helenice Mercier,

    1. Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, C.P. 11461, São Paulo, SP 05422-970, Brazil;
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  • Wolfgang Wanek

    1. Department of Chemical Ecology and Ecosystem Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria;
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Author for correspondence: Andreas Richter Tel: +43 14277 54252 Fax: +43 14277 9542 Email: andreas.richter@univie.ac.at

Summary

  • • In contrast to terrestrial plants, epiphytic tank bromeliads take up nutrients mainly over their tank leaf surface. The form in which nutrients are available in the tanks is determined by the source and the complex interplay between tank microbes, which transform them and the epiphytes that take them up.
  • • To elucidate the importance of different nitrogenous compounds for the nitrogen (N) nutrition of Vriesea gigantea from the Atlantic Rainforest, Brazil, N transformation processes in tank water as well as foliar uptake rates were estimated by 15N labelling techniques.
  • • Microorganisms actively transformed N compounds in the tank. Specifically, organic N compounds were rapidly mineralized to NH4+, while nitrification was negligible.
  • • Plants took up both organic and inorganic N forms, with a clear preference for NH4+. NH4+ comprised the largest and, because of fast mineralization rates, the most constant dissolved N pool in the tank water. Excretion of ureases by the plants together with an unusual uptake kinetic for urea also suggests that urea may be potentially important as an N source.

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