Question

Explain the mechanism of stomatal opening and closing.

Answer 1

The opening and closing of the stomata are described by different mechanisms, which depend upon the turgor pressure in the guard cells. The swelling of guard cells due to endosmosis of water causes the opening of stomatal pores while the shrinking of guard cells due to exosmosis closes the pores.

The opening and closing of stomata occurs due to turgor changes in guard cells. When guard cells are turgid, the stomatal pore is open while in flaccid conditions, the stomatal aperture closes. There are other theories that explain the opening and closing of the stomatal pore- Malate or $K^{+}$ ion pump hypothesis is the most accepted one.