Rockwell, Fulton .
Leaves as swelling tissues: poroelastic models of leaf water transport .
The movement of water through the leaf is known to contribute a large portion of the plant's total liquid phase resistance to transpiration, yet the nature of the flow path within the leaf, once outside the xylem, remains poorly understood. Progress in understanding the role of extraxylery liquid phase transport in transpiration depends on the availability of models that treat leaves as tissues, and moreover do so in terms of experimentally available parameters. In this spirit we develop a model for flow through leaf tissue as a poroelastic medium that describes leaf hydraulic properties in terms of a diffusivity, defined in terms of characteristics measurable on an entire leaf, and one fitted parameter, the Darcy permeability. The resistance contributed by the vasculature may be summarized by a single transport coefficient that appears in the boundary condition at the xylem- tissue interface, resulting in a Biot number that determines the order of the kinetics. As a description of the water transport capacity of leaf tissue, the Darcy permeability encompasses both apoplastic and symplastic pathways. As such, the model, once fitted, provides a framework for generating predictions on such aspects of leaf function as the proportion of the transpirational flux moving within the leaf in the vapor versus liquid phases, and the sufficiency of cell to cell flow to explain tissue transport.
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1 - Harvard University, Botanical Museum, 26 Oxford St, Cambridge, Massachusetts, 02138, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 551B/Convention Center
Date: Monday, August 2nd, 2010
Time: 3:30 PM