Nitrogen translocation as a function of the proportion of nitrate and ammonium

Abstract

An experiment was carried out utilizing Guimeagrass (Panicum maximum Jacq) in a nutritive solution, under greenhouse conditions. When the plants were 25 days old, groups of them received 100 ppm of nitrogen in the form of  NO^-₃/NH⁺₄ in the proportion of 100/0, 15/25, 50/50, 25/75 and 0/100. Six plants of eaçh group were cut at 1,5 cm from the base, 3, 24, 48 and 72 hours after the treatments. Xylem exudates were collected during 20 minutes. Nitrate represented about 80% of the xylem nitrogen in the 100/0 treatment. Ammonium varied from 7 to 15% depending on the treatments. Lysine, histidine, arginine, serine, alanine and glutamine were predominant in the highest nitrate treatments. On the other hand, asparagine and glutamine were predominant at higles ammonium concentration in the medium. Glutamine was the main organic nitrogen translocation.