What is diffusion pressure deficit? (DPD)
To understand the diffusion pressure deficit, first understand the terms osmotic pressure and turgor pressure.
Osmotic pressure is the pressure required to prevent solvent from passing through a semipermeable membrane from a region of higher concentration of solute to a region of lower concentration of solute.
Turgor pressure is the pressure of the cell contents against the cell wall in plant cells. In hypotonic solution, water diffuses into the cell and cells enlarge and extension growth occurs.As water diffuses in, cytoplasm builds up a pressure against the cell wall. This pressure is called turgor pressure.
Diffusion pressure deficit is the pressure which opposes the diffusion of water from the region of higher chemical potential to lower chemical potential. The two factors which determine the DPD are Osmotic pressure and the turgor pressure. It can be represented by a relation DPD = OP-wall pressure( turgor pressure)