Water potential: Water potential is a fundamental concept to understand water movement. It is denoted by yro. The pure water has the maximum water potential due to its greater kinetic energy. As both are related with the movement of water, water potential is expressed in pressure units such as pascal (Pa).
The water potential of pure water at standard temperatures, which are not under any pressure, is taken to be zero.
Solute potential (ys) and pressure potential (yp) are the two main components that affect water potential.
(a) Solute potential: All solutions have a lower water potential than pure water. The magnitude of this lowering due to dissolution of a solute is called solute potential devoted by p. The more the solute molecules, the lower is the ys.
For a solution at atmospheric pressure
|/W = |/S
(b) Pressure potential : If a pressure greater than atmospheric pressure, is applied to pure water or a solution, its water potential increases. Pressure potential is the pressure which develops in an osmotic system due to osmotic entry or exit of water i from it.
It is expressed by y . Its value is always in positive