K plays an important role in the metabolism of proteins and carbohydrates and is also essential for the synthesis of carbohydrates and translocation of carbohydrates to the roots. It is essential for photosynthesis, water and nutrient transport and increases root growth by activating a large number of enzymes including starch synthatase responsible for starch synthesis. Apart from these K is  involved in maintaining the cell turgidity improving the quality of the produce and imparting disease resistance

K deficiency is characterized by a marked reduction in plant height, petioles become shorter and leaves smaller. Under severe conditions, small purple or brown spots appear on the older leaves, which curl upwards from the margins and in some cases downward from the tip. As the deficiency intensifies, chlorotic areas develop on the tip and edges of lower leaves and lead to marginal necrosis. These leaves and their petioles grow old prematurely and fall. In a field experiment conducted in red loam soil in cassava variety Sree Vijaya, chlorosis followed by necrosis and  premature shedding of middle leaves were observed due to avoidance of K in the nutrient combination comprising of full N and full P, which indicated the significant role played by K in plant nutrition.