Potassium is one of the essential plant nutrient elements. It is used by plants in the synthesis and distribution of carbohydrates (25)2 and in the formation of proteins and oils. Potassium also seems to exert many of its effects by influencing enzymatic activity in cells. Potassium occurs as the monovalent cation on plant cells and undoubtedly exerts important effects upon such phnomona as the permiability of the cytoplasmic membranes and hydration of protoplasma. Plants assimilate potassium either from the soil solution or directly from the exchange complex.