title: Combined impacts of irradiance and dehydration on leaf hydraulic conductance: insights into vulnerability and stomatal control.
abstract: The leaf is a hydraulic bottleneck, accounting for a large part of plant resistance. Thus, the leaf hydraulic conductance (K(leaf) ) is of key importance in determining stomatal conductance (g(s) ) and rates of gas exchange. Previous studies showed that K(leaf) is dynamic with leaf water status and irradiance. For four species, we tested the combined impacts of these factors on K(leaf) and on g(s) . We determined responses of K(leaf) and g(s) to declining leaf water potential (Ψ(leaf) ) under low and high irradiance (<6 and >900 µmol photons m(-2) s(-1) photosynthetically active radiation, respectively). We hypothesized greater K(leaf) vulnerability under high irradiance. We also hypothesized that K(leaf) and g(s) would be similar in their responses to either light or dehydration: similar light-responses of K(leaf) and g(s) would stabilize Ψ(leaf) across irradiances for leaves transpiring at a given vapour pressure deficit, and similar dehydration responses would arise from the control of stomata by Ψ(leaf) or a correlated signal. For all four species, the K(leaf) light response declined from full hydration to turgor loss point. The K(leaf) and g(s) differed strongly in their light- and dehydration responses, supporting optimization of hydraulic transport across irradiances, and semi-independent, flexible regulation of liquid and vapour phase water transport with leaf water status.
authors: Université Bordeaux 1, Bâtiment B2 Avenue des Facultés, 33405 Talence, France Department of Ecology and Evolution, University of California Los Angeles, 621 Charles E. Young Drive South, Los Angeles, CA 90095, USA.
authors: Gaëlle
authors: G
authors: Guyot
authors: Christine
authors: C
authors: Scoffoni
authors: Lawren
authors: L
authors: Sack
mesh_terms: D003681:Dehydration; D035981:Hedera / Q000502:physiology* / Q000528:radiation effects; D006368:Helianthus / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D054046:Plant Stomata / Q000502:physiology / Q000528:radiation effects; D018526:Plant Transpiration / Q000502:physiology* / Q000528:radiation effects; D027824:Rosaceae / Q000502:physiology* / Q000528:radiation effects; D019666:Rubiaceae / Q000502:physiology* / Q000528:radiation effects; D013312:Stress, Physiological; D014867:Water / Q000502:physiology*
chemical_list: D014867:Water