Water potential $\left(\Psi\right)$ is the difference between the chemical potential of the water in a biological system and the chemical potential of pure water at the same temperature and pressure. The water potential of pure water is zero, and aqueous solutions of increasing concentration have increasingly negative values. Osmotic potential or solute potential $\left(\Psi_{s}\right)$ is a component of water potential. It can be defined as the amount by which the water potential is reduced as result of the presence of solute in it