Osmotic Function - Essential Elements
Plant cells generally contain mineral ions 10 to 1000 times higher in concentration than the surrounding soil. That is why water enters the cells by osmosis and builds up turgor. You know that turgor maintains the shape and size of non-rigid plant parts such as leaves. Potassium is a key ion in this respect. Changes in its concentration in guard cells affect turgor and thus result in opening and closing of stomata. Turgor is also essential for the growth of plant cells.