title: Reduced translocation of current photosynthate precedes changes in gas exchange for Quercus rubra seedlings under flooding stress.
abstract: Northern red oak (Quercus rubra L.) seedlings are frequently planted on suboptimal sites in their native range in North America, subjecting them to environmental stresses, such as flooding, for which they may not be well adapted. Members of the genus Quercus exhibit a wide range of responses to flooding, and responses of northern red oak to flooding remain inadequately described. To better understand the physiological effects of root system inundation in post-transplant northern red oak seedlings and the effects of flooding on endogenous patterns of resource allocation within the plant, we observed the effects of short-term flooding initiated at the linear shoot growth stage on net photosynthetic rates, dark respiration, chlorophyll fluorescence (Fv/Fm) and translocation of (13)C-labeled current photosynthate. Downward translocation of current photosynthate declined after 4 days of flooding and was the first measured physiological response to flooding; net photosynthetic rates decreased and dark respiration rates increased after 7 days of flooding. Short-term flooding did not affect maximal potential efficiency of photosystem II (Fv/Fm). The finding that decreased downward translocation of (13)C-labeled current photosynthate preceded reduced net photosynthesis and increased dark respiration during flooding suggests the occurrence of sink-limited photosynthesis under these conditions.
authors.affiliation: Hardwood Tree Improvement and Regeneration Center, Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47901-2061, USA Present address: John T. Harrington Forestry Research Center, New Mexico State University, PO Box 359, Mora, NM 87732, USA.
authors.forename: Joshua L
authors.initials: JL
authors.lastname: Sloan
authors.affiliation: Hardwood Tree Improvement and Regeneration Center, Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47901-2061, USA Present address: Kuwait Institute for Scientific Research, PO Box 24885, Safat 13109, Kuwait.
authors.forename: M Anisul
authors.initials: MA
authors.lastname: Islam
authors.affiliation: Hardwood Tree Improvement and Regeneration Center, Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47901-2061, USA djacobs@purdue.edu.
authors.forename: Douglass F
authors.initials: DF
authors.lastname: Jacobs
mesh_terms: D001692:Biological Transport; D011508:Chondroitin Sulfate Proteoglycans; D055868:Floods; D007632:Keratan Sulfate; D000071234:Lumican; D010788:Photosynthesis; D029963:Quercus / Q000378:metabolism*; D036226:Seedlings / Q000378:metabolism; D013312:Stress, Physiological; D014867:Water
chemical_list: D011508:Chondroitin Sulfate Proteoglycans; D000071234:Lumican; D014867:Water; D007632:Keratan Sulfate
keywords: 13C; Quercus morphological index; carbon translocation; chlorophyll fluorescence; dark respiration; photosynthesis