Abstract
Apart from having certain shortcomings in explaining observed facts, the cohesion theory of ascent of sap is shown to be untenable on thermodynamic grounds. A new mechanism for the transport of water and solutes in plants is suggested based on the formation of double layer suffice to balance gravity is provided by showing that the energy content of the double layer capacitor is of the same order of magnitude as the gravitational potential at 100 meters height for an equivalent mass of electrolyte. Thin films as well as filled columns of electrolyte can form in the lumen of vessels and tracheids, depending on the value of the charge density at the wall surfaces. The dynamics of this mechanism is based on the electrochemical gradient of water and solutes, i.e. on transpiration, but negative pressures are not required. Relative contributions of double layer films and intact columns to transport are estimated; the former is considered to be the durable and predominant mode of transport in tall trees.
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Amin, M. Ascent of sap in plants by means of electrical double layers. J Biol Phys 10, 103–109 (1982). https://doi.org/10.1007/BF01988693
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DOI: https://doi.org/10.1007/BF01988693