Potassium deficiency

Potassium (K)

K is an alkali metal with atomic number - 19 and atomic weight - 39.09. It is an essential macronutrient in plants. Plants absorb K in its ionic form (K+) from the soil water. It is considered as second most important nutrient after N and considered as quality nutrient. K is readily soluble in water and leaches from the soil with the water.


In plants K is required throughout the life-cycle in order to perform several functions.
  • K helps regulate the opening and closing of stomatal pores.
  • K is involved in enzyme activation, which regulate the starch, protein and ATP (Adenosine TriPhosphate) synthesis in plants.
  • K maintains ionic balance in the cytosol and vacuole.
  • K regulate the water balance in plants by controlling the absorption of water through the roots and transpiration through the stomatal pores.
  • K improves the drought resistance in plants.
  • K regulates translocation of photosynthates (carbohydrates) through the phloem.
  • K helps in cellulose synthesis and prevent lodging of plants.

Deficiency symptoms

K-deficient plants exhibit following symptoms.
  • General plant growth including roots, stems, leaves, fruits and seeds are reduced.
  • Characteristic symptoms of K deficiency in monocots is brown-scorching of leaves along the margins.
  • In dicots yellowing occurs between the veins.
  • As K is mobile in plants, in K-deficiency plant allocate K to younger leaves from the older leaves. Hence, yellowing of leaves starts from the lower(older) leaves.

potassium deficient paddy leaves
Rice leaves showing browning at the tip and margin

See also