The net force with which water is drawn into cell or root hair is equal to difference of OP and TP and known as diffusion pressure or suction pressure ie, SP or DPD = OP - TP. Osomotic pressure is the hydrostatic pressure developed in a solution when it is separated from pure solvent by a semipermeable membrane in a rigid vessel. Turgor pressure is the pressure with which the protoplasm press the cell wall. Root pressure is the pressure developing in tracheaiy element of xylem as a result of metabolic activities of roots. Root pressure cause guttation.