How does potassium help plants regulate moisture?
To put it simply, potassium regulates the opening and closing of plant stomata. Stomates are the pores on plant leaves that allow for gas and water vapor exchange.
When plants have adequate potassium, the guard cells swell and allow for complete closure of the stoma opening. However, when plants are potassium deficient, these guard cells do not function properly and moisture can escape.
Adequate potassium fertilization is essential for crops, specifically those under drought stress. When moisture is limiting, potassium is pumped out of the guard cells and the pores will close tightly, thus allowing for the conservation of water. Otherwise, plants would be more susceptible to drought.
Open stomate with expanded guard cells.
