preprints.org > biology and life sciences > forestry > doi: 10.20944/preprints202402.1074.v1

Preprint Hypothesis Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 19 February 2024 / Approved: 19 February 2024 / Online: 19 February 2024 (16:46:00 CET)

The theory of water transport in trees, according to which the main driving force of water movement is the suction created by the evaporation of water by the meniscus (the curved surface of the capillary liquid column) on the evaporating elements, supported from below by root pressure, is flawed. The capillary effect in nature is around one meter. In the case of open-air gaps, the leaf cannot suck in the water against gravity because, in this case, the plant would not be sucking in water, but air through the open-air gap. If not, how do trees transport water? When evaporation occurs, there is no suction towards the canopy, but pressure is due to a reduction in the cross-section of the water pipe caused by heat loss through evaporation. At night, when evaporation stops, a thermal equilibration process is triggered, which restores the original cross-section of the pipe. This generates suction and draws water from the soil. As the hydrostatic pressure in the pipe is high for tall trees, the pipe is cut off. To prove my theory, I have given several examples. Water transport is not based on physical mechanical laws alone. There may be complex physiological, biochemical, and biophysical processes behind the operation of the pipe system.

plant water transport, suction-pressure pipe, pulsating system, different time-phase cycle, aquaporin

Biology and Life Sciences, Forestry

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