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Plant Physiology 73:100-104 (1983) © 1983 American Society of Plant Biologists Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and 36ClO31I. Control of Net Uptake by NO3 EffluxBotany Department, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B1
A computer-controlled multichannel data acquisition system was employed to obtain continuous measurements of net nitrate or chlorate uptake by roots of intact barley plants (Hordeum vulgare cv Betzes) using nitrate-specific electrodes. Plants, previously grown in solutions maintained at 10 or 200 micromolar NO3 (low N or high N conditions, respectively), were provided with 200 micromolar NO3 or ClO3 during the uptake period. Initial rates of NO3 uptake were several times higher in low N plants than in high N plants. Within 10 min, uptake in the former plants declined to a new steady rate which was sustained for the remainder of the experiment. No such time-dependent changes were evident in the high N plants. Rates and patterns of net chlorate uptake exhibited almost identical dependence upon previous nitrate provision. NO3 (36ClO3) influx, by contrast, appeared to be independent of NO3 pretreatment prior to influx determination. Nitrate efflux, estimated by several different methods, was strongly correlated with internal nitrate concentration of the roots.
2 Present address: Botany School, University of Cambridge, Downing Street, Cambridge, CB2 3EA, England. 1 We acknowledge financial support from the Natural Sciences and Engineering Research Council of Canada. This article has been cited by other articles:
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