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https://hdl.handle.net/2440/44901
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DC Field | Value | Language |
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dc.contributor.author | Garnett, T. | - |
dc.contributor.author | Shabala, S. | - |
dc.contributor.author | Smethurst, P. | - |
dc.contributor.author | Newman, I. | - |
dc.date.issued | 2003 | - |
dc.identifier.citation | Functional Plant Biology: an international journal of plant function, 2003; 30(11):1165-1176 | - |
dc.identifier.issn | 1445-4408 | - |
dc.identifier.issn | 1445-4416 | - |
dc.identifier.uri | http://hdl.handle.net/2440/44901 | - |
dc.description.abstract | Ion-selective microelectrodes were used non-invasively to measure the concentration dependence of NH4+ and NO3– fluxes around the roots of intact solution-cultured Eucalyptus nitens (Deane & Maiden) Maiden. In addition, NH4+ and H+ fluxes were measured simultaneously at a range of NH4+ concentrations, and NO3– and H+ fluxes were measured simultaneously at a range of NO3– concentrations. Nitrogen concentrations ranged from 10–250 μM, i.e. in the range corresponding to the high affinity transport system (HATS). Both NH4+ and NO3– fluxes exhibited saturating Michaelis–Menten-style kinetics. The Km was 16 μM for NH4+ and 18 μM for NO3–. Values of V(max) were 53 nmol m–2 s–1 for NH4+ and 37 nmol m–2 s–1 for NO3–. Proton fluxes were highly correlated with NH4+ and NO3– fluxes, but the relationships were different. Proton efflux increased with increasing NH4+ concentration and mirrored the changing NH4+ fluxes. The ratio between NH4+ and H+ fluxes was 1 : –1.6. Proton influx was evident with initial exposure to NO3–, with the flux stoichiometry for NO3– : H+ being 1 : 1.4. Subsequent increases in NO3– concentration caused a gradual increase in H+ efflux such that the flux stoichiometry for NO3– : H+ became 1 : –0.8. The presence of 100 μM NH4+ greatly reduced NO3– fluxes and caused a large and constant H+ efflux. These results are evidence that E. nitens has a preference for NH4+ as a source of N, and that the fluxes of NH4+ and NO3– are quantitatively linked to H+ flux. | - |
dc.language.iso | en | - |
dc.publisher | C S I R O Publishing | - |
dc.source.uri | http://dx.doi.org/10.1071/fp03087 | - |
dc.subject | ammonium | - |
dc.subject | eucalyptus | - |
dc.subject | ion fluxes | - |
dc.subject | microelectrode | - |
dc.subject | nitrate | - |
dc.subject | proton | - |
dc.title | Kinetics of ammonium and nitrate uptake by eucalypt roots and associated proton fluxes measured using ion selective microelectrodes. | - |
dc.type | Journal article | - |
dc.contributor.organisation | Australian Centre for Plant Functional Genomics (ACPFG) | - |
dc.identifier.doi | 10.1071/FP03087 | - |
pubs.publication-status | Published | - |
dc.identifier.orcid | Garnett, T. [0000-0003-1664-9659] | - |
Appears in Collections: | Aurora harvest 6 Australian Centre for Plant Functional Genomics publications |
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