Studies of the uptake of nitrate in barley. II. Energetics
1990
Glass, A.D.M. | Siddiqi, M.Y. | Ruth, T.J. | Rufty, T.W. Jr
Q10 values for 13NO3(-1) influx were determined in 'uninduced' (NO3(-1)-starved) and 'induced' (NO3(-1)-pretreated) roots of barley (Hordeum vulgare L.) plants at various concentrations of external NO3(-1) ([NO3(-1)]o). At 0.02 mole per cubic meter [NO3(-1)]o, Q10 values for influx were from 3 to 4 between 5 and 10 degrees C. As [NO3(-1)]o increased Q10 values decreased, reaching values of 1.2 and 2.0, respectively, at 20 moles per cubic meter in uninduced and induced plants. The metabolic dependence of 13NO3(-1) influx at low and high [NO3(-1)]o (0.1 and 20.0 moles per cubic meter, respectively) in uninduced and induced plants was probed by the use of v arious inhibitors. These experiments confirmed the findings of the Q10 studies, demonstrating that at low [NO3(-1)]o 13NO3(-1) influx was extremely sensitive to metabolic inhibition. By contrast, at high [NO3(-1)]o, influx was relatively insensitive to the presence of inhibitors.
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