Water potential is denoted by the Greek letter ψ (psi) and is expressed in units of pressure called mega pascals (MPa).
The potential of pure water is designated a value of zero even though pure water contains plenty of potential energy.
Water always moves from a system with high potential to a system of low potential.
Water potential is what allows water to get into plant roots when there is more solute within the root cells than the water in the soil.
Formula to calculate water potential.
Pressure potential is the pressure exerted by the rigid cell wall of a plant that limits further water uptake. Pressure potential in animal cells is 0. It is measured in mega pascals (MPa).
Solute potential is a component of water potential that happens because solute molecules are present. It is always negative since solutes lower the water potential in a system. It is measured in mega pascals (MPa).
Calculate the water potential of a plant cell with a pressure potential of 0.8 MPa and an osmotic potential of -1.6 MPa.
Therefore, the water potential of the cell is -0.8 Mpa.