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Discrimination of nitrogen isotopes during absorption of ammonium and nitrate at different nitrogen concentrations by rice ( Oryza sativa L.) plants
Author(s) -
Yoneyama T.,
Matsumaru T.,
Usui K.,
Engelaar W. M. H. G.
Publication year - 2001
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.2001.00663.x
Subject(s) - oryza sativa , nitrogen , nitrate , nitrate reductase , chemistry , ammonium , fractionation , cultivar , absorption (acoustics) , paddy field , agronomy , biology , biochemistry , chromatography , materials science , organic chemistry , gene , composite material
Studies of uptake of ionic sources of N by two hydroponically grown rice ( Oryza sativa L.) cultivars (paddy‐field‐adapted Koshihikari and dryland‐adapted Kanto 168) showed that the magnitude of the nitrogen isotope fractionation (ɛ) for uptake of NH 4 + depended on the concentrations of NH 4 + and cultivar (averaging –6·1‰ for Koshihikari and –12·0‰ for Kanto 168 at concentrations from 40 to 200 mmol m − 3 and, respectively, –13·4 and –28·9‰ for the two cultivars at concentrations from 0·5 to 4 mol m − 3 ). In contrast, the ɛ for uptake of NO 3 − in similar experiments was almost insensitive to the N concentration, falling within a much narrower range (+3·2‰ to –0·9‰ for Koshihikari and –0·9‰ to –5·1‰ for Kanto 168 over NO 3 − concentrations from 0·04 to 2 mol m − 3 ). From longer term experiments in which Norin 8 and its nitrate‐reductase deficient mutant M819 were grown with 2 or 8 mol m − 3 NO 3 − for 30 d, it was concluded that the small concentration‐independent isotopic fractionation during absorption of this ion was not related to nitrate reductase activity.