The natural thermodynamic water transport by ad- and desorption forces at the stationary hygroscopic xylem/wood (Part of apoplast) of the intact plant body is described here. Contrary to the mechanic, hydraulic doctrine of textbooks, water in nature is held and moved at any plant height almost without tensile stress. It is well known that water enters the plant through a diffusion process (Osmosis) in liquid form, mostly via the root, and leaves it in vapor form via the leaf through diffusion (Transpiration). It is shown how the diffusive adsorption transport principle works. The partial dehydration (Desorption) of the plant, driven by transpiration, forms a combined concentration and adsorption-site gradient for water in the xylem matrix. Especially with open stomata a low moisture concentration and a high number of adsorption-sites for water (Sites with free van der Waals forces) can be found in the mesophyll cell walls (Part of apoplast) at the liquid - vapor boundary in the leaf. The water taken up by the root moves spontaneously (Adsorption) in the direction of this boundary and can thus partially or completely compensate the existing concentration- and adsorption-site differences for water. Physiologically an overlapping diffusive / adsorptive thermodynamic movement of moisture along the stationary hygroscopic xylem/wood takes place.
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Cell walls, unlike the walls of pipes, can ad- and desorb different amounts of water.
These hygroscopic and anatomic properties of xylem cells, which are ignored by proponents of hydraulic flow in plants, provide a clue to the natural, actual moisture transport principle: It is physically based on thermodynamic adsorption and desorption of water in the xylem.
This is described in more detail in the Preprints article: “Not Hydraulic but an Adsorption Water Transport occurs in the Xylem of Land Plants”.
Dipl.- Ing. FH; Dipl.- Biol. Univ
D - 90482 Nürnberg
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