The Primary Nutrients & Plant Growth - Potassium's Role

  • Potassium has many functions in plant growth. It is essential for photosynthesis
  • Activates enzymes to metabolize carbohydrates for the manufacture of amino acids and proteins
  • Facilitates cell division and growth by helping to move starches and sugars between plant parts,
  • Adds stalk and stem stiffness,
  • Increases disease resistance,
  • Increases drought tolerance,
  • Regulates opening and closing of stomata's,
  • Gives plumpness to grain and seed,
  • Improves firmness, texture, size and color of fruit crops and
  • Increases the oil content of oil crops.

Although not an integral part of cell structure, potassium regulates many metabolic processes required for growth, fruit and seed development. Many vegetable and fruit crops are high in potassium, which is vital for animal and human nutrition. Indeed, the health and survival of man and beast is dependent on potassium.

Potassium-deficient plants exhibit chlorosis (loss of green color) along the leaf margins or tips starting with the bottom leaves and progressing up the plant. In severe cases, the whole plant turns yellow, and the lower leaves fall off. As with other nutrients, lack of potassium causes stunted plants with small branches and little vigor. There are some crop-specific deficiency symptoms associated with potassium such as:

  • Grain crops like - corn, sorghum and small grains have weak stalks accompanied by reduced grain size and yield.
  • Cotton leaves turn reddish-brown, appear scorched, become bronze then black, and eventually fall off. Bolls are generally knotty, resulting in low quality fiber and poor yield.
  • Tomatoes exhibit uneven fruit ripening, poor texture and soft fruit.
  • The skin of stone fruits is distorted. The fruit is small and poor in quality.
  • Yield of forage crops is low, and quality is poor.

As a remedy, an application of potassium fertilizer will correct a deficiency and, if diagnosed early in the growing season, will benefit the current crop. Otherwise, the benefit of applying potassium will be for the following crop. Potassium can be obtained from fertilizers such as potassium nitrate (13-0-44), muriate of potash (0-0-60), potassium sulfate (0-0-50), or a mixture of potassium and magnesium sulfate (22% K2O). Most potash used for commercial crop production in India is either potassium chloride or potassium sulfate.