title: Leaf water stable isotopes and water transport outside the xylem.
abstract: How water moves through leaves, and where the phase change from liquid to vapour occurs within leaves, remain largely mysterious. Some time ago, we suggested that the stable isotope composition of leaf water may contain information on transport pathways beyond the xylem, through differences in the development of gradients in enrichment within the various pathways. Subsequent testing of this suggestion provided ambiguous results and even questioned the existence of gradients in enrichment within the mesophyll. In this review, we bring together recent theoretical developments in understanding leaf water transport pathways and stable isotope theory to map a path for future work into understanding pathways of water transport and leaf water stable isotope composition. We emphasize the need for a spatially, anatomically and isotopically explicit model of leaf water transport.
authors.affiliation: Centre for Carbon, Water and Food, University of Sydney, Brownlow Hill, New South Wales, 2570, Australia.
authors.forename: M M
authors.initials: MM
authors.lastname: Barbour
authors.affiliation: Research School of Biology, Australian National University, Acton, Australian Capital Territory, 0200, Australia.
authors.forename: G D
authors.initials: GD
authors.lastname: Farquhar
authors.affiliation: Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Narrabri, New South Wales, 2390, Australia.
authors.forename: T N
authors.initials: TN
authors.lastname: Buckley
mesh_terms: D001692:Biological Transport; D003903:Deuterium / Q000378:metabolism; D008954:Models, Biological; D010103:Oxygen Isotopes / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D014867:Water / Q000378:metabolism*; D052584:Xylem / Q000378:metabolism*
chemical_list: D010103:Oxygen Isotopes; D014867:Water; D003903:Deuterium
keywords: Péclet effect; hydraulic conductance; stable isotopes; transpiration; water relations