Potassium is essential in nearly all processes needed to sustain plant growth and reproduction. Plants deficient in potassium are less resistant to drought, excess water, and high and low temperatures. They are also less resistant to pests, diseases and nematode attacks. Because potassium improves the overall health of growing plants and helps them fight against disease, it is known as the "quality" nutrient. Potassium affects quality factors such as size, shape, color and vigor of the seed or grain, and improves the fiber quality of cotton.
Potassium enhances many enzyme actions aiding in photosynthesis and food formation. It builds cellulose and helps translocate sugars and starches. And it is vital to producing grains rich in starch.
Potassium maintains turgor and reduces water loss and wilting.
Potassium is known as the "quality nutrient" because of its important effects on factors such as size, shape, color, taste, shelf life, fiber and other quality-related measurements.
Comparing to Nitrogen
In many high-yielding crops, the K content in the plant is comparable to the nitrogen (N) content.
Potassium is absorbed by plants in the ionic form, indicated as K+.
Plants deficient in K are less resistant to drought, extreme temperatures and other stressors. Plants lacking K are also more susceptible to pests, diseases and nematode attacks.
Ample K can increase root growth and improves drought tolerance.
Potassium Deficiency Symptoms
Potassium is a highly mobile element in the plant and is translocated from the older to younger tissue. Consequently, potassium deficiency symptoms usually occur first on the lower leaves of the plant, and progress toward the top as the severity of the deficiency increases. One of the most common signs of potassium deficiency is the yellow scorching, or firing (chlorosis), along the leaf margin. In severe cases, the fired margin of the leaf may fall out. However, with broadleaf crops, such as soybeans and cotton, the entire leaf may shed, resulting in premature defoliation of the crop.Potassium-deficient crops grow slowly and have poorly developed root systems. Stalks are weak, and lodging of cereal crops such as corn and small grain is common. Legumes are not strong competitors for soil potassium and are often crowded out by grasses in a grass-legume pasture. When potassium is not sufficient, winter killing of perennial crops such as alfalfa and grasses can occur.