A comparison between ammonium and nitrate nutrition of young sugar-beet plants grown in nutrient solutions at constant acidity. 1. Production of dry matter, ionic balance and chemical composition.

Diploid sugar beet was grown in nutrient culture with ammonium and nitrate N in solutions kept at constant pH by automatic titration. Since plants given nitrate N yielded only 12% more than those given ammonium N, the effects of form of N on plant chemical composition could be determined. The excess of cations in the plant (C-A) was >3 times as great in plants given nitrate as in those given ammonium. The acidity evolved into the culture medium was a good measure of ammonium uptake, whereas with nitrate the amount of alkalinity evolved was unrelated to and small in comparison with the amount of nitrate absorbed. The rate of H+ production decreased during darkness and that of OH- decreased during or just after the dark phase. Levels of soluble carbohydrates in plants given nitrate were over twice as high as in those given ammonium. Data are given on levels of 6 organic acids, K, Na, Ca Mg, P, S and Cl. (Abstract retrieved from CAB Abstracts by CABI’s permission