Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Nitrogen uptake and translocation by Chara
    Vermeer, C.P. ; Escher, M. ; Portielje, R. ; Klein, J.J.M. de - \ 2003
    Aquatic Botany 76 (2003). - ISSN 0304-3770 - p. 245 - 258.
    ammonium uptake - phosphate-uptake - nutrient-uptake - nitrate - denitrification - communities - macrophytes - sediments - transport - fluxes
    The potential for above-ground and below-ground uptake and subsequent internal translocation of ammonium (NH4+) and nitrate (NO3-) by the macroalga Chara spp. was investigated. In a two compartment experimental set-up separating above-ground and below-ground algal parts, the charophytes were exposed to various combinations of N-15-labelled NH4+ and NO3-. Uptake in one compartment and translocation to the other were measured. Chara spp. was able to take up and translocate nitrogen between below-ground and above-ground parts. Uptake of (NH4+)-N-15 in rhizoids was two-fold higher than that of (NO3-)-N-15, indicating a preferential uptake of (NH4+)-N-15. Translocation after 5 days was always less in the direction from above-ground to below-ground parts (on average 2% of total N-15 uptake), than in the below-ground to above-ground direction (on average 29%). Translocation occurred when the ratio of N-15-atomic percentage in the algal material in the exposed compartment roughly exceeded 2%, and was thus more determined by the internal gradient in the N-15 content than by the nature of the N source (either NH4+ or NO3-). Translocation of N-15 from the below-ground to the above-ground compartment also occurred when the charophytes were exposed to high concentrations of either NO3- or NH4+ in the above-ground compartment. The results of this study are supportive for a mechanism with preferential uptake of NH4+ over NO3-, and subsequent passive diffusion between cells as the dominant transport mechanism. (C) 2003 Elsevier Science B.V. All rights reserved.
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