Annals of Botany 73: 337-343, 1994
© 1994 Annals of Botany Company
The Diurnal Pattern of Nitrate Uptake and Reduction by Spinach (Spinacia oleracea L.)
Horticulture Research International, Wellesbourne, Warwicks CV35 9EF, UK
Spinach plants were grown in bowls of aerated nutrient solution in a controlled environment chamber for 24 h, and harvested every 3·5-5 h to record their growth, nitrate and water uptake, and plant nitrate concentration. Twelve such experiments are described, either with a 14/10 h dark/light regime, or continuous light or darkness. The irradiance was either 110, 320, or 510 µmol m-2 s-1 (PPFD). All these regimes began at the end of the light period of a 14/10 h dark/light regime (510 µmol m-2 s-1) lasting approximately 2 weeks.
Nitrate uptake rate per g of dry weight of plant continued almost unabated at about 17 µmol h-1 through the initial 14-h dark period, and then fell away sharply if the light was not restored, but increased slightly when it was. With continuous light at 510 µmol m-2 s-1, uptake rate rose steadily for the first 24 h of light, and then fell sharply for about 6 h. Shoot nitrate concentration increased about three-fold in the dark phase, and declined in the light at a rate which was positively related to the irradiance. Root nitrate concentration was several times higher than that of the shoot: its diurnal change was smaller (relative to the mean) than that of the shoot. Nitrate reduction occurred to a small extent in the dark, and increased rapidly as soon as the lights came on, to remain at a roughly constant rate (related to the irradiance) throughout the light phase. Dry matter increase in the light was related to irradiance, but with little increase above 320 µmol m-2 s-1. Respiratory weight loss in the dark was not detectable. Rate of fresh weight increase was approximately constant throughout light and dark periods.
The results compare quite well with the predictions of a simple simulation model, based on the pump/leak principle.Copyright 1994, 1999 Academic Press
Spinacia oleracea, nitrate, uptake, reduction, influx, efflux, diurnal, regulation, model, simulation
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  Y.-P. Cen, D. H. Turpin, and D. B. Layzell Whole-Plant Gas Exchange and Reductive Biosynthesis in White Lupin Plant Physiology, August 1, 2001; 126(4): 1555 - 1565. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Aslam, R.L. Travis, and D.W. Rains Diurnal Fluctuations of Nitrate Uptake and In Vivo Nitrate Reductase Activity in Pima and Acala Cotton Crop Sci., March 1, 2001; 41(2): 372 - 378. [Abstract] [Full Text] [PDF]
|
|