A comparison between ammonium and nitrate nutrition of young sugar-beet plants grown in nutrient solutions at constant acidity. 2. Effect of light and carbohydrate supply.
AbstractThe effect of light and of glucose in the nutrient medium on the release of OH- or H+ and on ion accumulation by sugar beet plants grown with NO3 or NH4 nutrition was studied at a constant pH of 5.50. Decrease in OH- production rate in the dark was probably caused by retarded nitrate assimilation or carbohydrate shortage in the roots. Decrease in the rate of H+ production (NH4 uptake) in the dark was probably due to carbohydrate depletion. Both 24-h illumination and the addition of glucose increased H+ production during NH4 uptake and OH- production during NO3 uptake. 24 h darkness decreased the carboxylate pool on both N sources and it was tentatively concluded that light and darkness exert more influence on the carboxylate pool than N assimilation. Relationships between organic acid, carbohydrate and N metabolism, H+ or OH- production and inorganic composition were considered in detail. (Abstract retrieved from CAB Abstracts by CABIâ€™s permission)