Potassium, unlike other nutrients, K does not form compounds in plants, but remains free to ‘regulate’ many essential processes … including enzyme activation, photosynthesis, water use efficiency, starch formation, and protein synthesis. Agronomic crops contain about the same amounts of N and K, but K content of many high-yielding crops is even higher than that of N. Most soils contain large amounts of K, but only a small portion is available to plants over a growing season.
Symptom Description — One of the most common K deficiency symptoms is scorching or firing along leaf margins. Since K is mobile in the plant, deficiency symptoms appear on older leaves first. Potassium-deficient plants grow slowly and develop poor root systems. Stalks are weak and lodging is common. Seed and fruit are small and shriveled; crops show lower resistance to disease and moisture stress. Plants deficient in K are sensitive to disease infestation, and have poor fruit yield and quality.