There are three major components of water potential in a plant cell. These are-

a) Matric potential,

b) Solute potential and

c) Pressure potential.

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Water potential in a plant is the sum total of all these three. Matric potential represents the surface of the cell, soil etc., where hydro philic colloids are present and water molecules get absorbed to them, the matric potential (Ψm) is generally not significant in osmotic movement because it does not allow the free movement of water molecules.

Solute potential (Ψm)is also known as the osmotic potential. It may be de­fined as the amount by which water potential is reduced as a result of the presence of solute particles. Solute potential is always represented in nega­tive numbers (i.e., so much quantity of solvent is absent in comparison with a pure solvent)

Pressure potential (Ψp) is represented by the cell wall and cell membrane. The cell wall exerts a pressure (WP) on the cell contents. Similarly the cell membrane also exerts a pressure (ΨP) on the cell wall by virtue of its solvent content. The pressure potential is positive in that it denotes the amount of moisture already present. Hence water potential may be represented sym­bolically as follows.

Ψ = Ψm + Ψs + Ψp.