title: Ammonium and nitrate as nitrogen sources in two Eriophorum species.
abstract: We compared ammonium and nitrate nutrition in Eriophorum scheuchzeri and E. vaginatum, two Alaskan sedges that are native to high- and low-fertility sites, respectively. When grown in solution culture, the two species were similar in their kinetics of NHinf4sup+NOinf3sup-absorption: at nitrogen concentrations below 50 μM, net NHinf4sup+and NOinf3sup-were absorbed at similar rates, but at higher concentrations, net uptake of NOinf3sup-was significantly faster than that of NHinf4sup+. The two species also showed similar abilities to assimilate NOinf3sup-. Growth of E. vaginatum under NOinf3sup-nutrition was only slightly less than that under NHinf4sup+. The observed similarities between these species from contrasting edaphic habitats indicate that factors other than tissue-specific rates of nitrogen acquisition and assimilation may underlie local adaptation to soil N fertility. Moreover, the capacity of these species to exploit NOinf3sup-as a N source supports the view that NOinf3sup-availability may be significant even in wet, acidic, arctic soils.
authors.affiliation: Department of Vegetable Crops, University of California, 95616, Davis, CA, USA.
authors.forename: George W
authors.initials: GW
authors.lastname: Koch
authors.affiliation: Department of Vegetable Crops, University of California, 95616, Davis, CA, USA.
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Bloom
authors.affiliation: Department of Integrated Biology, University of California, 94720, Berkeley, CA, USA.
authors.forename: F Stuart
authors.initials: FS
authors.lastname: Chapin
keywords: Absorption; Ammonium; Eriophorum scheuchzeri; Eriophorum vaginatum; Nitrate