Potential organic and inorganic N uptake by six Eucalyptus species
C. R. WarrenSchool of Forest and Ecosystem Science, The University of Melbourne, Water Street, Creswick, Vic. 3363, Australia. Email: crwarren@unimelb.edu.au
Functional Plant Biology 33(7) 653-660 https://doi.org/10.1071/FP06045
Submitted: 6 March 2006 Accepted: 28 April 2006 Published: 3 July 2006
Abstract
There are no published studies of organic N uptake by species of south-eastern Australia (e.g. Eucalyptus) despite several studies of ecosystem N cycling. This study examines uptake of nitrate, ammonium and glycine (an amino acid) by six species of 16-year-old Eucalyptus growing at two plantations (‘common gardens’). By using two plantations, one xeric / oligotrophic and one mesic / eutrophic, I was able to disentangle genotypic from phenotypic differences in preference for N forms. Measurements were made on three separate occasions during spring. N uptake was examined in situ with attached roots placed in uptake solutions containing equimolar 100 μmol L–1 concentrations of 15N-nitrate, 15N-ammonium and 2-13C215N-glycine. Water and KCl extracts were used to determine the relative abundances of nitrate, ammonium and amino acids at the two plantations. Nitrate dominated at the eutrophic site, but was nearly absent at the oligotrophic site. N at the oligotrophic site was dominated by ammonium and amino acids which were present in similar concentrations. The rate of uptake of ammonium (6.3 ± 0.4 μmol g h–1; mean ± s.e., n = 108), was faster than glycine (3.4 ± 0.2), which was faster than nitrate (0.62 ± 0.07). Plant ‘preference’ for N forms did not vary between sites despite large differences in the relative abundances of N forms (nitrate v. ammonium v. amino acids). Hence, there was little evidence for acclimation of Eucalyptus species to differences in the relative availability of N forms. This study suggests the possibility for considerable organic N uptake in the field. Previous studies of ecosystem N cycling in south-eastern Australia have only examined inorganic N. The N cycle in south-eastern Australia needs to be revisited with a new perspective, one that considers inorganic N and organic N.
Keywords: amino acid, ammonium, common garden, Eucalyptus, glycine, nitrate, nitrogen, organic N, plantation, uptake.
Acknowledgments
This work was supported by funding from the Australian Research Council (discovery grant). At the time of writing, Charles Warren was the recipient of an APD fellowship from the Australian Research Council. None of this would have been possible without the support of Hancock Plantations Victoria, and its employees Stephen Elms and Richard Appleton. Numerous people contributed to the establishment and maintenance of the trials, particularly Phil Whiteman, Richard Appleton, Tom Baker, Richard Stokes, Paul Kneale and Michael Ryan.
Adams MA, Attiwill PM
(1982) Nitrate reductase-activity and growth-response of forest species to ammonium and nitrate sources of nitrogen. Plant and Soil 66, 373–381.
| Crossref | GoogleScholarGoogle Scholar |
Attiwill PM, Adams MA
(1993) Nutrient cycling in forests. New Phytologist 124, 561–582.
| Crossref | GoogleScholarGoogle Scholar |
Brooker MIH
(2000) A new classification of the genus Eucalyptus L’Her. (Myrtaceae). Australian Systematic Botany 13, 79–148.
| Crossref | GoogleScholarGoogle Scholar |
Chapin FS,
Moilanen L, Kielland K
(1993) Preferential use of organic nitrogen for growth by a nonmycorrhizal arctic sedge. Nature 361, 150–153.
| Crossref | GoogleScholarGoogle Scholar |
Garnett TP,
Shabala SN,
Smethurst PJ, Newman IA
(2003) Kinetics of ammonium and nitrate uptake by eucalypt roots and associated proton fluxes measured using ion selective microelectrodes. Functional Plant Biology 30, 1165–1176.
| Crossref | GoogleScholarGoogle Scholar |
Giblin AE,
Laundre JA,
Nadelhoffer KJ, Shaver GR
(1994) Measuring nutrient availability in arctic soils using ion-exchange resins — a field-test. Soil Science Society of America Journal 58, 1154–1162.
Hodge A,
Robinson D, Fitter A
(2000) Are microorganisms more effective than plants at competing for nitrogen? Trends in Plant Science 5, 304–308.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Jones DL,
Owen AG, Farrar JF
(2002) Simple method to enable the high resolution determination of total free amino acids in soil solutions and soil extracts. Soil Biology and Biochemistry 34, 1893–1902.
| Crossref | GoogleScholarGoogle Scholar |
Jones DL,
Healey JR,
Willett VB,
Farrar JF, Hodge A
(2005) Dissolved organic nitrogen uptake by plants — an important N uptake pathway? Soil Biology and Biochemistry 37, 413–423.
| Crossref | GoogleScholarGoogle Scholar |
Kaye JP, Hart SC
(1997) Competition for nitrogen between plants and soil microorganisms. Trends in Ecology and Evolution 12, 139–143.
| Crossref | GoogleScholarGoogle Scholar |
Kronzucker HJ,
Siddiqi MY, Glass ADM
(1997) Conifer root discrimination against soil nitrate and the ecology of forest succession. Nature 385, 59–61.
| Crossref | GoogleScholarGoogle Scholar |
McKane RB,
Johnson LC,
Shaver GR,
Nadelhoffer KJ, Rastetter EB , et al.
(2002) Resource-based niches provide a basis for plant species diversity and dominance in arctic tundra. Nature 415, 68–71.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Miller AE, Bowman WD
(2002) Variation in nitrogen-15 natural abundance and nitrogen uptake traits among co-occurring alpine species: do species partition by nitrogen form? Oecologia 130, 609–616.
| Crossref | GoogleScholarGoogle Scholar |
Miller AE, Bowman WD
(2003) Alpine plants show species-level differences in the uptake of organic and inorganic nitrogen. Plant and Soil 250, 283–292.
| Crossref | GoogleScholarGoogle Scholar |
Moore S
(1968) Amino acid analysis: aqueous dimethyl sulphoxide as solvent for the ninhydrin reaction. Journal of Biological Chemistry 243, 6281–6283.
| PubMed |
Murphy J, Riley JP
(1962) A modified single solution method for the determination of phosphate in natural waters. Analytica Chimica Acta 27, 31–36.
| Crossref | GoogleScholarGoogle Scholar |
Näsholm T, Persson J
(2001) Plant acquisition of organic nitrogen in boreal forests. Physiologia Plantarum 111, 419–426.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Näsholm T,
Huss-Danell K, Hogberg P
(2000) Uptake of organic nitrogen in the field by four agriculturally important plant species. Ecology 81, 1155–1161.
| Crossref | GoogleScholarGoogle Scholar |
Persson J, Näsholm T
(2001) Amino acid uptake: a widespread ability among boreal forest plants. Ecology Letters 4, 434–438.
| Crossref | GoogleScholarGoogle Scholar |
Persson J,
Hogberg P,
Ekblad A,
Hogberg MN,
Nordgren A, Näsholm T
(2003) Nitrogen acquisition from inorganic and organic sources by boreal forest plants in the field. Oecologia 137, 252–257.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Raven JA, Farquhar GD
(1990) The influence of N-metabolism and organic-acid synthesis on the natural abundance of isotopes of carbon in plants. New Phytologist 116, 505–529.
| Crossref | GoogleScholarGoogle Scholar |
Schmidt S, Stewart GR
(1999) Glycine metabolism by plant roots and its occurrence in Australian plant communities. Australian Journal of Plant Physiology 26, 253–264.
Skogley EO, Dobermann A
(1996) Synthetic ion-exchange resins: Soil and environmental studies. Journal of Environmental Quality 25, 13–24.
Stewart GR,
Pearson J,
Kershaw JL, Clough ECM
(1989) Biochemical aspects of inorganic nitrogen assimilation by woody-plants. Annales Des Sciences Forestieres 46, S648–S653.
Turnbull MH,
Goodall R, Stewart GR
(1995) The impact of mycorrhizal colonization upon nitrogen source utilization and metabolism in seedlings of Eucalyptus grandis Hill ex Maiden and Eucalyptus maculata Hook. Plant, Cell and Environment 18, 1386–1394.
| Crossref | GoogleScholarGoogle Scholar |
Turnbull MH,
Schmidt S,
Erskine PD,
Richards S, Stewart GR
(1996) Root adaptation and nitrogen source acquisition in natural ecosystems. Tree Physiology 16, 941–948.
| PubMed |
Warren CR, Adams MA
(2002) Possible causes of slow growth of nitrate-supplied Pinus pinaster. Canadian Journal of Forest Research 32, 569–580.
| Crossref | GoogleScholarGoogle Scholar |
Warren CR, Adams MA
(2004) Capillary electrophoresis of the major anions and cations in leaf extracts of woody species. Phytochemical Analysis 15, 407–413.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Weigelt A,
King R,
Bol R, Bardgett RD
(2003) Inter-specific variability in organic nitrogen uptake of three temperate grassland species. Journal of Plant Nutrition and Soil Science-Zeitschrift Fur Pflanzenernahrung Und Bodenkunde 166, 606–611.
| Crossref | GoogleScholarGoogle Scholar |
Weigelt A,
Bol R, Bardgett RD
(2005) Preferential uptake of soil nitrogen forms by grassland plant species. Oecologia 142, 627–635.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
Wright DE
(1962) Amino acid uptake by plant roots. Archives of Biochemistry and Biophysics 97, 174–180.
| Crossref | GoogleScholarGoogle Scholar | PubMed |
