title: Growth responses, biomass partitioning, and nitrogen isotopes of prairie legumes in response to elevated temperature and varying nitrogen source in a growth chamber experiment.
abstract: OBJECTIVE
  Because legumes can add nitrogen (N) to ecosystems through symbiotic fixation, they play important roles in many plant communities, such as prairies and grasslands. However, very little research has examined the effect of projected climate change on legume growth and function. Our goal was to study the effects of temperature on growth, nodulation, and N chemistry of prairie legumes and determine whether these effects are mediated by source of N.
  
  
  METHODS
  We grew seedlings of Amorpha canescens, Dalea purpurea, Lespedeza capitata, and Lupinus perennis at 25/20°C (day/night) or 28/23°C with and without rhizobia and mineral N in controlled-environment growth chambers. Biomass, leaf area, nodule number and mass, and shoot N concentration and δ(15)N values were measured after 12 wk of growth.
  
  
  RESULTS
  Both temperature and N-source affected responses in a species-specific manner. Lespedeza showed increased growth and higher shoot N content at 28°C. Lupinus showed decreases in nodulation and lower shoot N concentration at 28°C. The effect of temperature on shoot N concentration occurred only in individuals whose sole N source was N(2)-fixation, but there was no effect of temperature on δ(15)N values in these plants.
  
  
  CONCLUSIONS
  Elevated temperature enhanced seedling growth of some species, while inhibiting nodulation in another. Temperature-induced shifts in legume composition or nitrogen dynamics may be another potential mechanism through which climate change affects unmanaged ecosystems.
authors.affiliation: Department of Plant Biology, University of Minnesota, 1445 Gortner Avenue, Saint Paul, MN 55108, USA. whitt092@umn.edu
authors.forename: Heather R
authors.initials: HR
authors.lastname: Whittington
authors.forename: Laura
authors.initials: L
authors.lastname: Deede
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Powers
mesh_terms: D000704:Analysis of Variance; D018533:Biomass; D017753:Ecosystem; D007887:Fabaceae / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D009584:Nitrogen / Q000494:pharmacology*; D009586:Nitrogen Fixation / Q000187:drug effects; D009587:Nitrogen Isotopes; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development; D053204:Root Nodules, Plant / Q000187:drug effects / Q000254:growth & development; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D013696:Temperature
chemical_list: D009587:Nitrogen Isotopes; D009584:Nitrogen