employee
Rostov-na-Donu, Rostov-on-Don, Russian Federation
The work objective is a water movement modeling in the plant xylem allowing for the hydraulic loss on a single bordered pit torus, as well as on the pore population. However, as it follows from a number of publications, root pressure is not a mechanism providing water rising in plants. A model representation is based on the assumption that the main reason for rising water in plants is the surface tension in the meniscus of the xylem capillary. At this, it is necessary to take into account the xylem structure fea-tures of the needle-leaved and broadleaved trees. The equation to calculate the water rise in the xylem capillary of plants with tra-cheidal conductance is derived with account for the anatomy structure of the tracheids and bordered pores. The equation allows determining the change in the hydraulic losses in the movement of water through a single bordered pore and through the pore population taking into account the orientation of the latter. The model allows calculating the height of the water rise in the xylem capillary. It is shown that an increase in the diameter of the tra-cheid cavity and in the diameters of the bordered pore and torus, ceteris paribus leads to the rising of the hydraulic losses.
xylem, bordered pore. tracheid, trunk, plant, capillary
Введение. Наличие вертикального восходящего потока воды в ксилеме растений объясняется действием силы по-верхностного натяжения воды в менисках капилляров [1]. При объяснении подъема воды в капилляре радиуса r на высоту h традиционно рассматривают погруженный в воду стеклянный вертикальный капилляр и записывают условие равенства двух сил:
— силы, обусловленной весом столба воды в капилляре Р, направленной вертикально вниз,
—силы поверхностного натяжения воды в мениске капилляра Fн, направленной вверх.
Уравнение равновесия этих сил для цилиндрического капилляра записывается в виде
Р = Fн ↔ πr2 hρg = 2π r σ cos α, (1)
где ρ, g, α, σ — соответственно плотность воды, ускорение свободного падения, угол смачивания и коэффициент по-верхностного натяжения воды.
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