Portland State University. Department of Biology
Todd N. Rosenstiel
Term of Graduation
Date of Publication
Master of Science (M.S.) in Biology
Root Carbon Fixation, Root Respiration, PEP Carboxylase, Poplar, Rhizodeposition, Roots (Botany) -- Research, Plants -- Effect of atmospheric carbon dioxide on, Carbon dioxide -- Metabolism, Plants -- Respiration
1 online resource (v, 82 pages)
Roots live in and have evolved in a high carbon dioxide (CO₂) environment, yet relatively little research has been conducted on the impacts of soil dissolved inorganic carbon (DIC) on root metabolism. In this thesis, I explore the impacts of root-zone DIC on whole plant biomass accumulation, water use efficiency, and above-ground gas exchange. In addition, I explore the impacts of root-zone DIC on root processes: root PEP-Carboxylase activity, root respiration rate and root exudation of Krebs cycle organic acids.
Root-zone DIC did not impact biomass accumulation, leaf gas exchange parameters or water use efficiency under the growth conditions examined. Root-zone DIC did increase root PEP-Carboxylase activity, but decreased root respiration (both CO₂ production and O₂ consumption) and decreased organic acid exudation rates. Increase in measurement CO₂ partial pressure was found to cause an instantaneous decrease in root CO₂ production, and I provide evidence that changes in root metabolism (CO₂ uptake by roots) are part of the cause of this phenomenon. A hypothesized relationship between root respiration rate and Krebs cycle organic acid exudation was not supported by my data. I conclude that root-zone DIC has important impacts on critical functions of root metabolism, and should be considered as an important abiotic factor much in the same way atmospheric CO₂ is for leaves and whole plant biology.
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Matarese, Dawn Marie, "Impacts of Rhizosphere CO₂ on Root Phosphoenolpyruvate Carboxylase Activity, Root Respiration Rate and Rhizodeposition in Populus spp." (2011). Dissertations and Theses. Paper 345.