title: Impact of a short-term heat event on C and N relations in shoots vs. roots of the stress-tolerant C4 grass, Andropogon gerardii.
abstract: Global warming will increase heat waves, but effects of abrupt heat stress on shoot-root interactions have rarely been studied in heat-tolerant species, and abrupt heat-stress effects on root N uptake and shoot C flux to roots and soil remains uncertain. We investigated effects of a high-temperature event on shoot vs. root growth and function, including transfer of shoot C to roots and soil and uptake and translocation of soil N by roots in the warm-season drought-tolerant C4 prairie grass, Andropogon gerardii. We heated plants in the lab and field (lab=5.5days at daytime of 30+5 or 10°C; field=5days at ambient (up to 32°C daytime) vs. ambient +10°C). Heating had small or no effects on photosynthesis, stomatal conductance, leaf water potential, and shoot mass, but increased root mass and decreased root respiration and exudation per g. (13)C-labeling indicated that heating increased transfer of recently-fixed C from shoot to roots and soil (the latter likely via increased fine-root turnover). Heating decreased efficiency of N uptake by roots (uptake/g root), but did not affect total N uptake or the transfer of labeled soil (15)N to shoots. Though heating increased soil temperature in the lab, it did not do so in the field (10cm depth); yet results were similar for lab and field. Hence, acute heating affected roots more than shoots in this stress-tolerant species, increasing root mass and C loss to soil, but decreasing function per g root, and some of these effects were likely independent of direct effects from soil heating.
authors: Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, USA.
authors: Kumar P
authors: KP
authors: Mainali
authors: Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, USA. Electronic address: scott.heckathorn@utoledo.edu.
authors: Scott A
authors: SA
authors: Heckathorn
authors: Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, USA.
authors: Dan
authors: D
authors: Wang
authors: Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, USA.
authors: Michael N
authors: MN
authors: Weintraub
authors: DuPont Pioneer Hi-Bred, Johnston, IA 50131, USA.
authors: Jonathan M
authors: JM
authors: Frantz
authors: Department of Biology, Washington and Lee University, Richmond, VA 24450, USA.
authors: E William
authors: EW
authors: Hamilton
mesh_terms: D000222:Adaptation, Physiological; D031722:Andropogon / Q000502:physiology*; D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes; D019069:Cell Respiration; D006358:Hot Temperature; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D010788:Photosynthesis; D018517:Plant Roots / Q000378:metabolism*; D018520:Plant Shoots / Q000378:metabolism*; D054046:Plant Stomata / Q000502:physiology; D012987:Soil; D013312:Stress, Physiological; D013997:Time Factors
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D012987:Soil; D002244:Carbon; D009584:Nitrogen
keywords: Exudation; Heat wave; High temperature; Nutrients; Roots