Potassium deficiency (plants)

[2] Plants require potassium ions (K+) for protein synthesis and for the opening and closing of stomata, which is regulated by proton pumps to make surrounding guard cells either turgid or flaccid.

Potassium also functions in other physiological processes such as photosynthesis, protein synthesis, activation of some enzymes, phloem solute transport of photoassimilates into source organs, and maintenance of cation:anion balance in the cytosol and vacuole.

[3] Deficient plants may be more prone to frost damage and disease, and their symptoms can often be confused with wind scorch or drought.

The deficiency is most common in several important fruit and vegetable crops; notably potatoes, brassicas, tomatoes, apples, currants, gooseberries, and raspberries.

Leaves will also develop small, dark brown spots on the undersides and a bronzed appearance on the upper surfaces.

In agriculture, some cultivars are more efficient at K uptake due to genetic variations, and often these plants have increased disease resistance.

Silica, which is accumulated in greater quantities when adequate potassium is present, is incorporated into cell walls, strengthening the epidermal layer which functions as a physical barrier to pathogens.

[5] When potassium is readily available in the soil, a plant absorb it through plasma membrane channels and high-affinity H+/K+ transporters and store it in vacuoles.