Stomata open or close depending on the urgency of the occlusive cells that form it. If they swell because they receive water from the adjacent cells, the stoma opens, as its cell walls buckle, with which gases enter or leave through the ostiole. If on the contrary, the adjacent cells absorb the water from the occlusives and these, ultimately, lose water, they become flaccid and the stoma closes, allowing neither the exit nor the entry of gases. Other factors that influence the regulation of stomatal opening and closing are the circadian rhythm (day / night) and the concentration of CO2.
Explanation:
A stoma is basically a pore that is used for gas exchange with the environment and the transpiration of the plant. It is surrounded by two cells, called occlusive or guard cells, these have chloroplasts and have a thickening on their adjacent surfaces. Stomatal movements depend on changes in the turgor pressure of the occlusive cells and adjacent epidermal cells. Stomata open when water diffuses through osmosis into the occlusive cells from the surrounding epidermal cells. As the turgor pressure increases in the stomatal cells, it induces them to swell and the stomata open. In contrast, when the turgor pressure decreases, the occlusive cells become flaccid and the thickened walls come together, closing the pore. Other factors that influence the regulation of stomatal opening and closing are the circadian rhythm (day / night) and the concentration of CO2. Guard cells regulate the opening of stomata by integrating different signals, both endogenous and exogenous (environmental).Stomatal opening occurs when the concentration of CO2 in the occlusive cell decreases as a result of photosynthesis, while it closes when this concentration increases, even in the presence of light. The plants implement a temporary regulation of the stomata to limit water losses during the CO2 absorption process, that is, the stomata are opened during the day and closed at night to prevent unnecessary water losses, since during this period, photosynthesis does not occur and there is no demand for CO2. With the first rays of sunlight, the plant again begins to photosynthesize, again the stomata open since the demand for CO2 is high. The stomatal opening favors the transpiration of the plant.
