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UPTAKE OF ORGANIC NITROGEN IN THE FIELD BY FOUR AGRICULTURALLY IMPORTANT PLANT SPECIES

UPTAKE OF ORGANIC NITROGEN IN THE FIELD BY FOUR AGRICULTURALLY IMPORTANT PLANT SPECIES Uptake of glycine was studied in four plants commonly used in grasslands in northern Europe ( Phleum pratense, Trifolium hybridum, T. pratense, and Ranunculus acris ) and compared to uptake of ammonium and nitrate. The experiment was conducted in the field, but with plants transferred to pots with soil 8––10 d before the start of the experiment. Plant uptake of U- 13 C 2 15 N glycine, 15 NH 4 ++ , and 15 NO 3 −− was studied by injecting dilute (1 mmol/L) solutions of respectively labeled N source into the pots and harvesting plants 21 h later. Measurements of 13 C and 15 N in roots showed that, in all plants, part of the glycine N was taken up in the form of intact amino acid. Hence, regressions of plots of excess 13 C against excess 15 N showed that a minimum of 19––23%% of the glycine-derived N was taken up as intact amino acid; possible losses of labeled C atoms of glycine during its metabolism in the plants implies that these estimates are conservative. Uptake of the different N sources was similar in the two Trifolium species, while rates of nitrate uptake were comparably high in P. pratense, and rates of glycine uptake were comparably low in R. acris. 15 N labeling of shoots was detected in all species, whereas significant levels of 13 C tracer was only found in shoots of P. pratense. It is concluded that a capacity for uptake of organic N exists also in an agricultural setting, despite the rapid turnover of organic N usually found under such conditions. This adds to the growing knowledge of plant utilization of organic N sources in natural ecosystems and stresses the need for reexamining this step in the biogeochemical N cycle. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Ecology Ecological Society of America

UPTAKE OF ORGANIC NITROGEN IN THE FIELD BY FOUR AGRICULTURALLY IMPORTANT PLANT SPECIES

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Publisher
Ecological Society of America
Copyright
Copyright © 2000 by the Ecological Society of America
Subject
Articles
ISSN
0012-9658
DOI
10.1890/0012-9658%282000%29081%5B1155:UOONIT%5D2.0.CO%3B2
Publisher site
See Article on Publisher Site

Abstract

Uptake of glycine was studied in four plants commonly used in grasslands in northern Europe ( Phleum pratense, Trifolium hybridum, T. pratense, and Ranunculus acris ) and compared to uptake of ammonium and nitrate. The experiment was conducted in the field, but with plants transferred to pots with soil 8––10 d before the start of the experiment. Plant uptake of U- 13 C 2 15 N glycine, 15 NH 4 ++ , and 15 NO 3 −− was studied by injecting dilute (1 mmol/L) solutions of respectively labeled N source into the pots and harvesting plants 21 h later. Measurements of 13 C and 15 N in roots showed that, in all plants, part of the glycine N was taken up in the form of intact amino acid. Hence, regressions of plots of excess 13 C against excess 15 N showed that a minimum of 19––23%% of the glycine-derived N was taken up as intact amino acid; possible losses of labeled C atoms of glycine during its metabolism in the plants implies that these estimates are conservative. Uptake of the different N sources was similar in the two Trifolium species, while rates of nitrate uptake were comparably high in P. pratense, and rates of glycine uptake were comparably low in R. acris. 15 N labeling of shoots was detected in all species, whereas significant levels of 13 C tracer was only found in shoots of P. pratense. It is concluded that a capacity for uptake of organic N exists also in an agricultural setting, despite the rapid turnover of organic N usually found under such conditions. This adds to the growing knowledge of plant utilization of organic N sources in natural ecosystems and stresses the need for reexamining this step in the biogeochemical N cycle.

Journal

EcologyEcological Society of America

Published: Apr 1, 2000

Keywords: agricultural plants ; amino acid ; ammonium ; glycine ; 15 N and 13 C ; nitrate ; organic nitrogen uptake ; Phleum pratense; ; Ranunculus acris; ; stable isotopes ; Trifolium hybridum; ; Trifolium pratense.

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