Turgidity

Turgidity, or turgor, describes the state of fullness of a plant cell when the vacuole is inflated with water and presses the cytoplasm against the cell wall. The resulting turgor pressure arises from osmosis: water moves into the cell in response to a water potential gradient between the cell’s interior and its surroundings. The cell wall provides resistance to expansion, converting inward pressure into outward force that stiffens tissues and helps maintain plant form.

Turgor pressure drives cell enlargement during growth, as the wall loosens enough for water-driven expansion. It also helps nonwoody parts stand upright and supports the opening and closing of stomata. Guard cells change their turgor to regulate gas exchange and water loss, illustrating how cellular water status translates into organ-level functions.

Environmental and physiological factors influence turgidity. Soil moisture, temperature, and solute concentrations affect water potential and water movement. In hypotonic environments, cells become more turgid; in hypertonic conditions, water exits the cells and plasmolysis can occur, leading to wilting. Recovery through rehydration restores turgor and tissue rigidity.

Measurement and relevance: turgor can be assessed with methods such as a cell pressure probe or related manometric techniques that estimate internal pressure against the cell wall. Understanding turgidity is central to plant physiology, influencing irrigation strategies, drought responses, and the mechanical properties of tissues.