Potassium has been described as the “quality element” for crop production. Potassium can also positively affect crop quality indirectly provided that it effectively interacts with other nutrients and production practices.

Examples of the role of potassium as the “quality element”:

• Potassium facilitates the absorption of nitrogen stimulating the translocation of amino-acids from vegetative shoots to the grain that promotes the synthesis of gluten and prolamines as well as the formation of proteins that improve baking quality.
• Potassium application increases the starch content of rice, wheat, soybean, sesame, and some other forage crops.
• Potassium increases oil content in sesame, soybean, rape, groundnut, and cotton seeds.
• Potassium increases protein and vitamin C content in potatoes. In addition, it increases the yield of large and medium-sized tubers and decreases weight loss in tubers after harvest. Potassium deficiency causes accumulation of reducing sugars and decreases starch content in potato tubers. Potato chips made of such tubers are dark in color.
• Potassium increases the size of cotton balls, improves micronaire value, fiber strength, and increases the percentage of mature fibers.
• In citruses potassium positively affects rind thickness and improves fruit color. It also enhances the contents of citric and ascorbic acids (vitamin C) in the juice and positively affects other juice characteristics such as the acid/sugar ratio and the content of soluble solids.
• A poor supply of potassium in bananas results in thin fragile bunches with a shorter shelf life.
• Potassium increases the amounts of solids, sugars, acids, and carotene in fruits and vegetables, as well as extends their shelf life.