Nitrate,ammonium and amino acids in the bleeding sap of tomato plants in relation to form and concentration of nitrogen in the medium

Summary When nitrate was raised from 6 to 12 meq/l of nutrient solution there was little change in the sap concentration, but the translocation rate of nitrate (exudation rate × concentration) increased considerably. Sap concentration and transport of glutamine, NH₄-ions, leucine and transport of asparagine also increased. Replacement of nitrate by ammonium immediately enhanced sap concentration and transport especially of glutamine. Initially sap concentration and transport of ammonium increased in a similar way, but a few hours later they decreased to that of plants with high nitrate. re]19750318Institute für Pflanzenernährung der T.U. Hannover