title: Studies of the Uptake of Nitrate in Barley: I. Kinetics of NO(3) Influx.
abstract: (13)NO(3) (-) was used to investigate patterns of NO(3) (-) influx into roots of barley plants (Hordeum vulgare L. cv Klondike) previously grown with (;induced') or without (;uninduced') a source of external NO(3) (-) ([NO(3) (-)](0)). In both induced and uninduced plants, (13)NO(3) (-) influx was biphasic in the range from 0.005 to 50 moles per cubic meter [NO(3) (-)](0). In the low concentration range (<1 mole per cubic meter for induced plants and <0.3 mole per cubic meter for uninduced plants), influx was saturable and V(max) and K(m) values for influx either increased or decreased according to NO(3) (-) pretreatment. By contrast, (13)NO(3) (-) influx in the high concentration range revealed a strictly linear concentration dependence. These fluxes appeared to be mediated by a constitutive, rather than an inducible, transport system.
authors: Department of Botany, University of British Columbia, Vancouver, B.C., Canada V6T 2B1.
authors: M Y
authors: MY
authors: Siddiqi
authors: A D
authors: AD
authors: Glass
authors: T J
authors: TJ
authors: Ruth
authors: T W
authors: TW
authors: Rufty