Question

what are the factors that control the stomatal openings??
Pls answer fast very urgent

Answer 1

1. Light:

Among external factors, light plays predominant role in the movement of guard cells. Blue and red light are effective in both photosynthesis and stomatal opening. However, blue light is found to be more effective (relative to red light) in causing stomatal opening than in photosynthesis.

At low light levels, blue light may cause stomatal opening when red light has no effect at all. Blue light causes movement of K+. It is now thought that blue light promotes the breakdown of starch into the PEP molecules that can accept CO2producing malic acid.

2. Water Content of Epidermal Cells:

The movement of guard cells is turgor phenomenon and guard cells derive water from the adjoining epidermal cells and hence water content of the latter is bound to effect this phenomenon.

3. Temperature:

Increase in the temperature causes stomata to open. Temperature has significant effect on the permeability of the wall of the guard cells and therefore greatly affect the osmotic phenomenon which is responsible for the movement of these cells.

4. Mineral Elements:

Deficiency of certain mineral elements like nitrogen, phosphorus and potassium has some effect on the opening and closing of stomata (Desai, 1937).