Display Settings:


Send to:

Choose Destination
See comment in PubMed Commons below
Plant Physiol. 1983 Sep;73(1):105-10.

Short Term Studies of Nitrate Uptake into Barley Plants Using Ion-Specific Electrodes and ClO(3): II. Regulation of NO(3) Efflux by NH(4).

Author information

  • 1Botany Department, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B1.


The influence of NH(4) (+), in the external medium, on fluxes of NO(3) (-) and K(+) were investigated using barley (Hordeum vulgare cv Betzes) plants. NH(4) (+) was without effect on NO(3) (-) ((36)ClO(3) (-)) influx whereas inhibition of net uptake appeared to be a function of previous NO(3) (-) provision. Plants grown at 10 micromolar NO(3) (-) were sensitive to external NH(4) (+) when uptake was measured in 100 micromolar NO(3) (-). By contrast, NO(3) (-) uptake (from 100 micromolar NO(3) (-)) by plants previously grown at this concentration was not reduced by NH(4) (+) treatment. Plants pretreated for 2 days with 5 millimolar NO(3) (-) showed net efflux of NO(3) (-) when roots were transferred to 100 micromolar NO(3) (-). This efflux was stimulated in the presence of NH(4) (+). NH(4) (+) also stimulated NO(3) (-) efflux from plants pretreated with relatively low nitrate concentrations. It is proposed that short term effects on net uptake of NO(3) (-) occur via effects upon efflux. By contrast to the situation for NO(3) (-), net K(+) uptake and influx of (36)Rb(+)-labeled K(+) was inhibited by NH(4) (+) regardless of the nutrient history of the plants. Inhibition of net K(+) uptake reached its maximum value within 2 minutes of NH(4) (+) addition. It is concluded that the latter ion exerts a direct effect upon K(+) influx.

Free PMC Article
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk