K Potassium in the soil to KCl, K2SO4 and other forms of salt in the water dissociated into K + and was absorbed by the roots. Potassium is present in the plant and mainly concentrated in the most vigorous parts of life activities, such as growth points, forming layers, young leaves and so on.

Potassium is related to the synthesis of carbohydrates. When the barley and pea seedlings were deficient in potassium, the synthesis of starch and sucrose was slow, leading to the accumulation of monosaccharides. When the potash was sufficient, the contents of sucrose, starch, cellulose and lignin were higher and the accumulation of glucose was less. Potassium can also promote the transport of sugars into the storage organs, so the sugar-rich storage organs (such as potato tubers, beetroot and starch seeds) potassium content more. Therefore, potash can increase the sweetness of the fruit and widely used in watermelon,tomato,potato,grape.