Rates and Pathways for Water Diffusion and Bulk Flow Through Leaf Tissue: A New Technique for an Old Problem
Chemistry and Biochemistry
Nuclear magnetic resonance was used to measure the relative content of [H-1] nuclei in Acer platanoides leaf discs floating on either sucrose/D2O or concentrated PEG/H2O solutions. Data show that water diffusion and bulk flow follow different pathways through leaf tissue. Isotope exchange data fit accurately an equation derived for diffusion through a homogeneous medium with an average diffusion coefficient of 3.3 x 10(-10) m(2) s(-1). A diffusion model featuring cell wall barriers was shown to be unnecessary. The diffusion rate is too fast to be consistent with transport solely through apoplastic channels and instead, water molecules appear to move directly through contiguous compartments. The discs lost water by osmosis into the PEG solution with an exponential decay function, which was shown to be consistent with a fractal model of bulk flow. (C) 1997 Elsevier Science Ireland Ltd.
McCain, D. C.
(1997). Rates and Pathways for Water Diffusion and Bulk Flow Through Leaf Tissue: A New Technique for an Old Problem. Plant Science, 125(1), 113-117.
Available at: http://aquila.usm.edu/fac_pubs/5322