Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

Rapid, Reversible Inhibition of Nitrate Influx in Barley by Ammonium

R. B. LEE and M. C. DREW
Journal of Experimental Botany
Vol. 40, No. 216 (July 1989), pp. 741-752
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/23692331
Page Count: 12
  • Download ($42.00)
  • Cite this Item
Rapid, Reversible Inhibition of Nitrate Influx in Barley by Ammonium
Preview not available

Abstract

The rate of influx of nitrate into the roots of intact barley plants was measured over a period of 3—5 min from external nitrate concentrations of 1—150 mmol m-3, using 13N-labelled nitrate as tracer. Ammonium at external concentrations of 0.005—50 mol m-3 inhibited nitrate influx in a manner which did not conform to a simple kinetic model but increased approximately as the logarithm of the ammonium concentration. At any particular ammonium concentration, inhibition of nitrate influx reached its full extent within 3 min of the ammonium being supplied and was not made more severe by up to 17 min pre-treatment with ammonium. On removing the external ammonium, nitrate influx returned to its original rate within about 3 min. Potassium at 0.005—50 mol m-3 did not reproduce the rapid effect of ammonium on nitrate influx. Net uptake of nitrate also decreased when ammonium was supplied, over a similar timescale and to a similar extent as nitrate influx. The decrease in nitrate influx caused by ammonium was sufficient to account for the observed reduction in net uptake, without necessitating any acceleration of nitrate efflux.

Page Thumbnails

  • Thumbnail: Page 
[741]
    [741]
  • Thumbnail: Page 
742
    742
  • Thumbnail: Page 
743
    743
  • Thumbnail: Page 
744
    744
  • Thumbnail: Page 
745
    745
  • Thumbnail: Page 
746
    746
  • Thumbnail: Page 
747
    747
  • Thumbnail: Page 
748
    748
  • Thumbnail: Page 
749
    749
  • Thumbnail: Page 
750
    750
  • Thumbnail: Page 
751
    751
  • Thumbnail: Page 
752
    752