title: Hydroponics versus field lysimeter studies of urea, ammonium and nitrate uptake by oilseed rape (Brassica napus L.).
abstract: N-fertilizer use efficiencies are affected by their chemical composition and suffer from potential N-losses by volatilization. In a field lysimeter experiment, (15)N-labelled fertilizers were used to follow N uptake by Brassica napus L. and assess N-losses by volatilization. Use of urea with NBPT (urease inhibitor) showed the best efficiency with the lowest N losses (8% of N applied compared with 25% with urea alone). Plants receiving ammonium sulphate, had similar yield achieved through a better N mobilization from vegetative tissues to the seeds, despite a lower N uptake resulting from a higher volatilization (43% of applied N). Amounts of (15)N in the plant were also higher when plants were fertilized with ammonium nitrate but N-losses reached 23% of applied N. In parallel, hydroponic experiments showed a deleterious effect of ammonium and urea on the growth of oilseed rape. This was alleviated by the nitrate supply, which was preferentially taken up. B. napus was also characterized by a very low potential for urea uptake. BnDUR3 and BnAMT1, encoding urea and ammonium transporters, were up-regulated by urea, suggesting that urea-grown plants suffered from nitrogen deficiency. The results also suggested a role for nitrate as a signal for the expression of BnDUR3, in addition to its role as a major nutrient. Overall, the results of the hydroponic study showed that urea itself does not contribute significantly to the N nutrition of oilseed rape. Moreover, it may contribute indirectly since a better use efficiency for urea fertilizer, which was further increased by the application of a urease inhibitor, was observed in the lysimeter study.
authors: Université de Caen Basse-Normandie, UMR 950 Ecophysiologie Végétale, Agronomie et nutritions N, C, S, Esplanade de la Paix, F-14032 Caen Cedex, France. arkoun.mustapha@etu.unicaen.fr
authors: Mustapha
authors: M
authors: Arkoun
authors: Xavier
authors: X
authors: Sarda
authors: Laëtitia
authors: L
authors: Jannin
authors: Philippe
authors: P
authors: Laîné
authors: Philippe
authors: P
authors: Etienne
authors: José-Maria
authors: JM
authors: Garcia-Mina
authors: Jean-Claude
authors: JC
authors: Yvin
authors: Alain
authors: A
authors: Ourry
mesh_terms: D001692:Biological Transport; D029688:Brassica napus / Q000254:growth & development / Q000378:metabolism*; D004777:Environment; D005308:Fertilizers / Q000032:analysis; D005969:Glutamate Dehydrogenase / Q000378:metabolism; D018527:Hydroponics; D016623:Ion Pumps / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012987:Soil / Q000737:chemistry*; D014508:Urea / Q000378:metabolism
chemical_list: D005308:Fertilizers; D016623:Ion Pumps; D009566:Nitrates; D009587:Nitrogen Isotopes; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D012987:Soil; D014508:Urea; D005969:Glutamate Dehydrogenase; D009584:Nitrogen