Factors Affecting Stomatal Movement

Factors Affecting Stomatal Movement

There are a number of factors which influence stomatal movements. These include light, temperature, potassium chloride, organic acid, carbondioxide concentration, water and abscissic acid.

Light

Light greatly influences the opening and closing of stomata as it stimulates production of malic acid due to conversion of starch to sugar. Stomata do not open in U-V light and green light but remain opened in the blue and red regions of the spectrum.

Temperature

Stomata open with rise in temperature and close at lower temperature as light and temperature are directly related. But higher temperatures also cause stomatal closure.

Potassium Chloride

Accumulation of potassium chloride causes opening of stomata.

Organic Acid

The increase of organic acid content in the guard cells causes the stomata to open.

Carbondioxide Concentration

Stomatal movement is influenced by the concentration of carbondioxide. At low concentrations of CO₂, the stomata open. With increase in the concentration of CO₂, the stomata begin to close and when CO₂ concentration of cells is higher than its concentration in the air, the stomata completely close.

Stomatal movement is always influenced by the CO₂ concentration of the intercellular spaces of the leaf and not the concentration of the air.

Water

Water is responsible for causing changes in the turgor of the guard cells. Guard cells become flaccid on losing water and so the stomata close. Similarly the guardcells become fully turgid on gaining water and the stomata open. Under conditions of water scarcity also, the stomata close.

Abscissic Acid

Abscissic acid accumulates in the leaves when the plants experience water stress or water deficit. It has been observed, that ABA (Abscissic acid) stimulates closure of stomata under these conditions.