Diffusion Pressure Deficit

in a plant cell, the pressure (S) equal to the difference between the osmotic pressure (P) and the turgor pressure (T). When the osmotic and turgor pressures are equal, the plant does not absorb water. In cells of terrestrial plants, the osmotic pressure usually somewhat exceeds the turgor pressure (P > T); the greater the difference between the pressures, the more intensively the cells absorb water. The diffusion pressure deficit depends on the type of plant cell, the height of the cell’s location in the plant, the substrate, atmospheric humidity, and wind velocity. It fluctuates between 0.1 and 100 atmospheres; when it exceeds 10 atmospheres, irrigation of crops is necessary.