The pressure which needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane is said to be the solute potential. Solute potential (Ψs) decreases with increasing solute concentration; a decrease in Ψs causes a decrease in the total water potential.
Pressure potential is the hydrostatic pressure exerted on the water present in a cell. It increases when the turgidity of the cell increases. It is usually positive but is negative in the xylem which plays a major role in water transport up in a stem.