Significance of root pressure
ROOT PRESSURE is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves.
Root pressure is also linked to the phenomenon of guttation, i.e., the loss of water in the form of liquid droplets from the vein endings of certain herbaceous plants.
Root pressure is only able to transport water up to small heights. However, it helps in re-establishing the continuous chains of water molecules in the xylem. Transpirational pull maintains the flow of water molecules from the roots to the shoots.
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Root pressure is the pressure exerted by the cortical cells of the root upon their liquid contents, under fully turgid condition, forcing a quantity of them into the xylem vessels and through them upward into the stem .