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Free amino acids in Arctic salt mars...

Henry, Hugh Allen Lorenzo.

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Free amino acids in Arctic salt marsh coastal sites and plant nitrogen acquisition.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Free amino acids in Arctic salt marsh coastal sites and plant nitrogen acquisition./
Author:	Henry, Hugh Allen Lorenzo.
Description:	206 p.
Notes:	Adviser: Robert L. Jefferies.
Contained By:	Dissertation Abstracts International64-04B.
Subject:	Biogeochemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NQ78024
ISBN:	0612780244

Free amino acids in Arctic salt marsh coastal sites and plant nitrogen acquisition.
Henry, Hugh Allen Lorenzo.

Free amino acids in Arctic salt marsh coastal sites and plant nitrogen acquisition. - 206 p.

Adviser: Robert L. Jefferies.

Thesis (Ph.D.)--University of Toronto (Canada), 2003.

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 <italic>Puccinellia phryganodes</italic> 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 <super>15</super>N 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 <super>13</super>C and <super>15</super>N into plant roots following injection of <super>13</super>C<super>15</super>N-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.

ISBN: 0612780244Subjects--Topical Terms:

545717
Biogeochemistry.

Free amino acids in Arctic salt marsh coastal sites and plant nitrogen acquisition.
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020 $a 0612780244
035 $a (UnM)AAINQ78024
035 $a AAINQ78024
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100 1 $a Henry, Hugh Allen Lorenzo. $3 1261566
245 1 0 $a Free amino acids in Arctic salt marsh coastal sites and plant nitrogen acquisition.
300 $a 206 p.
500 $a Adviser: Robert L. Jefferies.
500 $a Source: Dissertation Abstracts International, Volume: 64-04, Section: B, page: 1593.
502 $a Thesis (Ph.D.)--University of Toronto (Canada), 2003.
520 $a 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 <italic>Puccinellia phryganodes</italic> 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 <super>15</super>N 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 <super>13</super>C and <super>15</super>N into plant roots following injection of <super>13</super>C<super>15</super>N-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.
590 $a School code: 0779.
650 4 $a Biogeochemistry. $3 545717
650 4 $a Biology, Botany. $3 1017825
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Biology, Plant Physiology. $3 1017865
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710 2 0 $a University of Toronto (Canada). $3 1017674
773 0 $t Dissertation Abstracts International $g 64-04B.
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791 $a Ph.D.
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856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NQ78024