Question

Very Short Answer Type :
What is the importance of potassium in the opening and closing of stomata ?

Answer 1

Accumulation of $K^{+}$ in guard cells in light increases the osmotic potential of the guard cells; this causes opening of stoma. In dark, $K^{+}$ moves out of the guard cells and their osmotic potential becomes less negative. Thus water osmoses out of the guard cells and their turgidity decreases. This causes stomatal closure.