Question

What is root pressure?

Answer 1

Root pressure is osmatic pressure ( osmosis is the movement of a solvent through a semi-permeable membrane into a solution of higher solute concentration tend to equalize the concentration of solute on the sides of the membrane ) within the cells of a root which causes the sap to rise through a plant stem to the leaves. Root pressure occurs in the xylem of vascular plants. When soil moisture level is high either at night or when transpiration is low during day.

Use of root pressure for plant :

Root pressure 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 shoot . When the nutrients are absorbed by root hairs,water along with minerals,increases the pressure in the xylem. This pressure pushes the water up upto small heights. Root pressure is associated with phenomenon of guttation , ie loss of water in the form of liquid droplets from the vein endings of certain herbaceous plants.