In 1908, scientist Lloyd expressed the theory about the opening and closing of stomata.
(i) Mechanism of stomatal closure
According to this theory, osmotic pressure changes for the exchange of sugar and nitrogen in the guard cell and stomatal opening and closing depend on the osmotic pressure variation. As urine is insoluble in its presence, the osmotic pressure of the sarcophagus decreases and water escapes from the sarcophagus in the process of exudation. The guard cells lose water and become silent and the stomata close.
(ii) Stomatal opening technique
Soluble sugar is produced by converting the white matter of the guard cell. This increases the density of the guard cells and water enters the guard cells by the process of endorespiration. The guard cell takes up water and swells and the stomata open.
