What is the water potential and what are the factors affecting the water potential?
Water potential is the chemical energy or chemical potential of the water which is measured in pressure terms and affected by pressure and concentration gradient. It refers to the free energy of water molecules. It is represented by the sign of psi (Ψ). Water potential is zero for pure water. This water potential is the total of solute potential, matric potential, and pressure potential Ψ=Ψm+Ψs+ΨpΨ=Ψm+Ψs+Ψp. The movement of water occurs from high water potential to low water potential. When the hydrostatic pressure increases, the water moves from outside into the cell. The difference between outside and inside pressure of the cell is reduced that increases the solute pressure (Ψs). The movement of water from outside towards inside the cell occurs due to the gradient of water potential. The factors affecting water potential are given below: a. Solute potential (Ψs) b. Matric potential (Ψm) c. Pressure potential (Ψp) The solute potential is represented by Ψs and is always negative whereas the pressure potential is mostly positive and denoted by Ψp. Therefore, water potential is mainly affected by the solute pressure and pressure potential because of Ψ = Ψs + Ψp.
