Specific response of sugar beet cultivars to different nitrogen forms

Six cultivars of sugar beet characterized by different sugar contents were grown in water culture on Reid-York nutrient solution for 30 days. Nitrogen was included in the medium in the form of either NH₄NO₃, NH₄Cl or Ca(NO₃)₂ at the concentrations 105, 210 and 420 mg N/l. The results obtained reveal that both shoot dry weight and leaf area were dependent upon the type of cultivar and the form and concentration of nitrogen present in the nutrient solution. The least amount of shoot matter and the smallest leaf area were obtained in the presence of ammonium as the sole nitrogen source. The concentration of total nitrate and ammonium nitrogen measured in the shoot was found to be dependent on the cultivar type and on the concentration of nitrogen present in the nutrient solution. The highest oxalic acid concentrations were detected in plants grown on nitrate. No synthesis of oxalic acid was detected upon growth on ammonium as the sole nitrogen source.