Role of potassium & zinc on sweet potato

The Sweet potato (Ipomoea batatas L.) is a dicotyledonous plant that belongs to the family Convolvulaceae. It is grown as a starchy food crop throughout the tropical, sub-tropical and frost-free temperate climatic zones in the world. It is believed to have originated in Central America and the North Western part of South America Sweet potato is cultivated in more than 100 countries (Woolfe, 1992). It is the seventh among all food crops worldwide from the point of view of total production, thirteenth in value of production and fifth in calorific contribution to human diet (Bouwkamp, 1985 and Tortoe, 2010). In India, it is mainly cultivated in Bihar, Orissa, Uttar Pradesh, Madhya Pradesh, Maharashtra, Karnataka and approximately 80 per cent of the World's sweet potato is grown in Asia, 15 per cent in Africa and about 5 per cent in rest of the World. The total area in the world under sweet potato is estimated to be 7.95 million ha with a production of 104.26 million tonnes. In India, sweet potato covers 1.11 lakh hectare area, producing 11.32 lakh tonnes tubers, with the productivity of 10.1 metric tonnes per hectare (Anonymous, 2013).