Root stress is the stress that occurs in the xylem vessels as a result of the metabolic activity of the root. Absorption of water by the rhizomes results in chlorosis of the outer layer of the plant cells. The stress exerted by the cells of the root cortex when fully inflated is called root stress.

The pressure exerted by the cell wall on the protoplasm due to buoyancy or turgidity is called wall pressure.

The pressure exerted by the protoplasm on the cell wall due to turgidity is called turgor pressure.

When water enters the cell in the process of osmosis, the volume of the cell increases and the cell swells. This condition is called gas inflation or turgidity. Diffusion pressure deficit (DPD) occurs due to gas inflation.

When water escapes from the cell, the protoplasm shrinks, this is called plasmolysis. When water enters the plyomylated cells, the protoplasm expands, this is called deplasmolysis.

Osmotic pressure is the ability of two solutions of different concentrations at the same atmospheric pressure and temperature to move the solute from the lower concentration region to the higher concentration region when separated by a semipermeable membrane.

When two solutions of different concentrations are separated by a semipermeable membrane at the same atmospheric pressure and temperature, the movement of solute from the lower concentration region to the higher concentration region is called osmosis. Osmosis is of two types. Endogenous and exogenous. The movement of solutes from outside the cell into the cell is called endocytosis and the movement of solutes from inside the cell to the outside of the cell is called efflux. Substances that cause water to enter cells are called osmotic agents.

The pressure due to which water enters the cell is called diffusional pressure deficit. In modern language it is called pani bibhava. The water absorption capacity of cells is dependent on DPD. DPD = OP-TP.

The latent ability of molecules of a substance to spread from an area of higher concentration to an area of lower concentration at the same atmospheric pressure and temperature is called diffusion pressure.

Diffusion is the movement of molecules of a substance from an area of higher concentration to an area of lower concentration at the same atmospheric pressure and temperature.