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Current issue   Ukr. J. Phys. 2015, Vol. 59, N 8, p.781-786
doi:10.15407/ujpe59.08.0781    Paper

Ludanov K.I.

National Technical University of Ukraine “Kyiv Polytechnical Institute”
(14, Politechnichna Str., Kyiv 03056, Ukraine)

Transpiration Mechanism of Capillary Transport in the Xylem of Plants

Section: Soft matter
Original Author's Text: Ukrainian

Abstract: The capillary transport of the aqueous solution of mineral salts in the xylem of plants owing to the transpiration process has been considered. By analyzing the balance of driving forces (capillary forces, gravity forces, and viscous friction), a differential equation describing the liquid flow in the xylem consisting of capillaries with varying cross-sections is derived and integrated. The profile of a vertical capillary with varying cross-section for the maximum water flow is calculated. On the basis of the formula obtained for the minimum capillary crosssection and the Thomson law for the vapor pressure over the concave meniscus of leaf stoma, an expression is obtained for the dependence of the maximum capillary length on the humidity of the atmospheric air.

Key words: xylem, transpiration, capillary transport, meniscus radius, leaf stoma, capillary profile, altitude scale.