Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition
The importance of free amino acids as a source of plant nitrogen was examined in an Arctic coastal salt-marsh. Concentrations of inorganic nitrogen in salt-marsh soils were low relative to those reported for most temperate soils, whereas soluble organic nitrogen concentrations of salt-marsh soils we...
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Ottawa : National Library of Canada = Bibliothèque nationale du Canada
2004
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ftyorkuniv:oai:yorkspace.library.yorku.ca:10315/14541 2023-10-01T03:53:31+02:00 Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition Henry, Hugh A.L. 2004 application/pdf http://hdl.handle.net/10315/14541 en eng Ottawa : National Library of Canada = Bibliothèque nationale du Canada http://hdl.handle.net/10315/14541 http://www.collectionscanada.gc.ca/thesescanada/ http://www.collectionscanada.gc.ca/obj/s4/f2/dsk4/etd/NQ78024.PDF plant nitrogen Arctic coastal salt-marsh Puccinellia phryganodes Electronic Thesis or Dissertation 2004 ftyorkuniv 2023-09-02T23:02:31Z The importance of free amino acids as a source of plant nitrogen was examined in an Arctic coastal salt-marsh. Concentrations of inorganic nitrogen in salt-marsh soils were low relative to those reported for most temperate soils, whereas soluble organic nitrogen concentrations of salt-marsh soils were relatively high; the median ratio of free amino acid nitrogen as a proportion of ammonium nitrogen was 0.36 and amino acid concentrations exceeded those of ammonium in 24% of samples. Growth of the salt-marsh grass 'Puccinellia phryganodes' on glycine in a continuous flow hydroponic medium was similar to growth on ammonium ions at an equivalent concentration of nitrogen. Furthermore, in short-term excised root uptake experiments, rates of glycine uptake were equal to rates of ammonium and nitrate uptake combined when roots were provided with all three nitrogen substrates at equal concentrations. Amino acid uptake relative to ammonium uptake was favoured at high temperatures, high salinity and low pH. Free amino acids turned over rapidly in the soil, with half-lives in the soil solution ranging from 8-23 h for glycine, compared with ranges of 6-15 h and 6-16 h for ammonium and nitrate ions, respectively. Plant incorporation of 15N tracer injected into soil cores was 56, 83, and 68% of incorporation by soil microorganisms for glycine, ammonium and nitrate ions, respectively. The simultaneous incorporation of 13C and 15N into plant roots following injection of 13C15N-glycine into soil cores indicated that at least a portion of this amino acid was absorbed intact. In a model of the dynamics of nitrogen movement in an Arctic salt-marsh grazed and grubbed by geese, the direct uptake of organic nitrogen by plant roots was required to obtain rates of mineralization consistent with empirical estimates. Overall, these results indicate that free amino acids are likely a substantial contribution to plant nitrogen nutrition in Arctic coastal marshes. Thesis Arctic Puccinellia phryganodes York University, Toronto: YorkSpace Arctic |
institution |
Open Polar |
collection |
York University, Toronto: YorkSpace |
op_collection_id |
ftyorkuniv |
language |
English |
topic |
plant nitrogen Arctic coastal salt-marsh Puccinellia phryganodes |
spellingShingle |
plant nitrogen Arctic coastal salt-marsh Puccinellia phryganodes Henry, Hugh A.L. Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition |
topic_facet |
plant nitrogen Arctic coastal salt-marsh Puccinellia phryganodes |
description |
The importance of free amino acids as a source of plant nitrogen was examined in an Arctic coastal salt-marsh. Concentrations of inorganic nitrogen in salt-marsh soils were low relative to those reported for most temperate soils, whereas soluble organic nitrogen concentrations of salt-marsh soils were relatively high; the median ratio of free amino acid nitrogen as a proportion of ammonium nitrogen was 0.36 and amino acid concentrations exceeded those of ammonium in 24% of samples. Growth of the salt-marsh grass 'Puccinellia phryganodes' on glycine in a continuous flow hydroponic medium was similar to growth on ammonium ions at an equivalent concentration of nitrogen. Furthermore, in short-term excised root uptake experiments, rates of glycine uptake were equal to rates of ammonium and nitrate uptake combined when roots were provided with all three nitrogen substrates at equal concentrations. Amino acid uptake relative to ammonium uptake was favoured at high temperatures, high salinity and low pH. Free amino acids turned over rapidly in the soil, with half-lives in the soil solution ranging from 8-23 h for glycine, compared with ranges of 6-15 h and 6-16 h for ammonium and nitrate ions, respectively. Plant incorporation of 15N tracer injected into soil cores was 56, 83, and 68% of incorporation by soil microorganisms for glycine, ammonium and nitrate ions, respectively. The simultaneous incorporation of 13C and 15N into plant roots following injection of 13C15N-glycine into soil cores indicated that at least a portion of this amino acid was absorbed intact. In a model of the dynamics of nitrogen movement in an Arctic salt-marsh grazed and grubbed by geese, the direct uptake of organic nitrogen by plant roots was required to obtain rates of mineralization consistent with empirical estimates. Overall, these results indicate that free amino acids are likely a substantial contribution to plant nitrogen nutrition in Arctic coastal marshes. |
format |
Thesis |
author |
Henry, Hugh A.L. |
author_facet |
Henry, Hugh A.L. |
author_sort |
Henry, Hugh A.L. |
title |
Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition |
title_short |
Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition |
title_full |
Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition |
title_fullStr |
Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition |
title_full_unstemmed |
Free amino acids in Arctic salt-marsh coastal sites and plant nitrogen acquisition |
title_sort |
free amino acids in arctic salt-marsh coastal sites and plant nitrogen acquisition |
publisher |
Ottawa : National Library of Canada = Bibliothèque nationale du Canada |
publishDate |
2004 |
url |
http://hdl.handle.net/10315/14541 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Puccinellia phryganodes |
genre_facet |
Arctic Puccinellia phryganodes |
op_relation |
http://hdl.handle.net/10315/14541 |
op_rights |
http://www.collectionscanada.gc.ca/thesescanada/ http://www.collectionscanada.gc.ca/obj/s4/f2/dsk4/etd/NQ78024.PDF |
_version_ |
1778520157113548800 |