pressure potential Symbol Ψ_p. The component of water potential due to the hydrostatic pressure that is exerted on water in a cell. In turgid plant cells it usually has a positive value as the entry of water causes the protoplast to push against the cell wall (see turgor). In xylem cells there is a negative pressure potential, or tension, as a result of transpiration. Water at atmospheric pressure has a pressure potential of zero.

pressure potential The hydrostatic pressure to which water in a liquid phase is subjected. It was known formerly as wall pressure or turgor pressure. In a turgid plant cell, pressure potential is usually positive but the pressure potential of xylem in a transpiring plant, which is under considerable tension, will be negative.

pressure potential The hydrostatic pressure to which water in a liquid phase is subjected. It was formerly known as wall pressure or turgor pressure. In a turgid plant cell, pressure potential is usually positive but the pressure potential of xylem in a transpiring plant, which is under considerable tension, will be negative.