Journal of Plant Growth Regulation

, Volume 30, Issue 2, pp 144–157

Nitrogen Form Alters Hormonal Balance in Salt-treated Tomato (Solanum lycopersicum L.)

  • Michel Edmond Ghanem
  • Cristina Martínez-Andújar
  • Alfonso Albacete
  • Hana Pospíšilová
  • Ian C. Dodd
  • Francisco Pérez-Alfocea
  • Stanley Lutts


Mixed nitrate/ammonium fertilization can partially alleviate the negative effects of salinity on growth of some plant species compared to all-nitrate or all-ammonium fertilization. To gain insights about the mechanisms involved, tomato (Solanum lycopersicum L. cv Moneymaker) plants were grown hydroponically for 3 weeks with two NO3/NH4+ fertilization regimes (6/0.5 and 5/1.5; Ntotal = 6.5 mM) in the absence (control) or presence of salt stress (100 mM NaCl). Ammonium enrichment had no effect on growth and other parameters under control conditions. Under salinity, however, ammonium enrichment improved shoot and root biomass by 20% and maintained leaf PSII efficiency close to control levels. These changes were related to higher leaf K+, NO3, and NH4+ concentrations and activities of the N-assimilatory enzymes glutamate synthase (GOGAT) and glutamine synthase (GS) in the leaves. Ammonium enrichment also attenuated the salt-induced increase in leaf abscisic acid (ABA) concentration and decrease in leaf concentrations of indole 3-acetic acid (IAA) and the cytokinins trans-zeatin (tZ) and trans-zeatin riboside (tZR). Enhanced cytokinin status was probably due to maintenance of root-to-shoot cytokinin transport and decreased leaf induction of the cytokinin-degrading enzyme cytokinin oxidase/dehydrogenase (CKX) under ammonium-enriched conditions. It is concluded that nitrogen form modifies salinity-induced physiological responses and that these modifications are associated with changes in plant hormone status.


Abscisic acid Ammonium Cytokinin Indole-3-acetic acid Nitrate Nitrogen metabolism Plant hormones Salt stress Sodium chloride Tomato (Solanum lycopersicum L.) trans-Zeatin trans-Zeatin riboside 


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Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Michel Edmond Ghanem
    • 1
  • Cristina Martínez-Andújar
    • 2
    • 5
  • Alfonso Albacete
    • 2
    • 6
  • Hana Pospíšilová
    • 3
  • Ian C. Dodd
    • 4
  • Francisco Pérez-Alfocea
    • 2
  • Stanley Lutts
    • 1
  1. 1.Groupe de Recherche en Physiologie végétale, Earth and Life InstituteUniversité catholique de LouvainLouvain-la-NeuveBelgium
  2. 2.Departamento de Nutrición VegetalCentro de Edafología y Biología Aplicada del Segura (CEBAS), Consejo Superior de Investigaciones Científicas (CSIC)Espinardo, MurciaSpain
  3. 3.Department of BiochemistryPalacký UniversityOlomoucCzech Republic
  4. 4.The Lancaster Environment CentreLancaster UniversityLancasterUK
  5. 5.Department of Horticulture-Seed BiologyOregon State UniversityCorvallisUSA
  6. 6.Plant Physiology Group, Institute of Plant SciencesKarl-Franzens University of GrazGrazAustria

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