What happens when a pressure greater than the atmospheric pressure is applied to pure water or a solution?
If a pressure greater than atmospheric pressure is applied to pure water or a solution, its water potential increases.
It is equivalent to pumping water from one place to another.
Pressure can be built up in a plant system when water enters a plant cell due to diffusion against the cell wall. It makes the cell turgid, this increases the pressure potential.
Pressure potential is usually positive.