title: Kinetics of ammonium and nitrate uptake among wild and cultivated tomatoes.
abstract: Concentration dependence of net ammonium and nitrate uptake was monitored for a cultivar of tomato, Lycopersicon esculentum, and two accessions of a neotropical wild relative, L. hirsutum. The kinetics of net NH4+uptake differed among these taxa and were not dependent on the ionic composition of the nutrient solution. The kinetics of net NO3-uptake were dependent on the composition of the nutrient solution; the presence of NH4+or Cl-enhanced net NO3-uptake for the cultivated species and for a highland accession of the wild species. The capacity for net NO3-uptake was greater than the capacity for net NH4+uptake in all three taxa; the proportion of NO3-to NH4+absorbed was much greater for the wild taxa. Our data suggest that NO3-may be a more important source of mineral nitrogen than NH4+for these tropical taxa.
authors.affiliation: Department of Vegetable Crops, University of California, 95616, Davis, CA, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Smart
authors.affiliation: Department of Vegetable Crops, University of California, 95616, Davis, CA, USA.
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Bloom
keywords: Ammonium; Nitrate; Tomato; Tropical; Uptake