Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and ClO(3): I. Control of Net Uptake by NO(3) Efflux |
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| Authors: | Deane-Drummond C E Glass A D |
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| Affiliation: | Botany Department, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B1. |
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| Abstract: | 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. |
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