Turgor pressure

Diagram illustrating turgor pressure in plant cells.

Turgor pressure is the pressure exerted by the fluid (usually water) inside the cell against the cell wall. It is a critical factor in maintaining the structural integrity and rigidity of plant cells, allowing them to remain turgid and upright. Turgor pressure is essential for various physiological processes in plants, including growth, nutrient transport, and the opening and closing of stomata.

Mechanism

Turgor pressure is generated when water enters the plant cell by osmosis, causing the vacuole to swell. The cell wall, being rigid, resists this expansion, creating pressure within the cell. This pressure is balanced by the osmotic pressure of the cell's contents, maintaining the cell's shape and firmness.

A turgid plant cell.

Importance in Plants

Turgor pressure plays a vital role in maintaining the plant's structure. It helps keep the plant upright and supports the leaves and flowers. When turgor pressure is lost, plants wilt and droop, as seen in conditions of water scarcity.

Growth and Movement

Turgor pressure is also involved in plant growth and movement. It drives cell expansion, which is crucial for plant growth. Additionally, it is involved in rapid movements such as the closing of Mimosa pudica leaves and the explosive dispersal of seeds in plants like the squirting cucumber.

The squirting cucumber uses turgor pressure for seed dispersal.

Environmental Adaptations

Plants have adapted to various environments by modifying their turgor pressure. For example, some plants can grow in rocky environments by exerting pressure to break through hard surfaces.

A tree growing out of rock, demonstrating the power of turgor pressure.

Stomatal Function

Turgor pressure is crucial in the opening and closing of stomata, which are small openings on the leaf surface that regulate gas exchange and water loss. Changes in turgor pressure in the guard cells surrounding each stoma control its aperture.

Stomata opened and closed due to changes in turgor pressure.

Applications

Turgor pressure is measured using a device called a pressure bomb or pressure chamber, which helps in understanding plant water status and irrigation needs.

A pressure bomb used to measure turgor pressure.

Related Pages

• Osmosis
• Cell wall
• Vacuole
• Stomata
• Mimosa pudica

References

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  Sismonastia of the Mimosa pudica
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  Shaggy Ink Caps busting through asphalt