ISSN:
1365-3040
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
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 NH4+ depended on the concentrations of NH4+ 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 NO3− 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 NO3− 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 NO3− 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-3040.2001.00663.x
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