Potassium and integrated nutrient management in potato.

Potato crop has strict requirement for a balanced fertilizati on management, without which growth and development of the crop are poor and both yield and quality of tubers are diminished. Among the major nutrients, potassium not only improves yields but also benefits various aspects of quality. Some of the tuber quality parameters affected by potassium nutrition are: tuber size, percentage of dry matter, starch content, internal blackening, storability and resistance to mechanical damage. Potassium also provides resistance against pest and diseases and drought and frost stresses. At present, average yield of potato in India is about 19 t/ha, which is much below the crop potential productivity. Low use of fertilizers and serious imbalances in the N:P:K application ratio are partially responsible for this low yield. Current fertilization rates are insufficient to sustain high yields and to replenish nutrient removal by the crop. Field experiments jointly conducted by IPI, PRII and CPRI at Shimla and Jalandhar show that a balanced N x K fertilization increased tuber yield. Increasing K doses decreased the yield of small grade tubers and increased the proportion of large marketable tubers. Potassium application also dramatically decreased the incidence of late blight. In 1998, a maximum yield of 40.8 t ha -1 was obtained at Kufri (Shimla) when applied 180 kg N ha -1 , 100 kg P2O5 ha -1 and 150 kg K2O ha -1 , against a tuber yield of only 14.6 t/ha -1 at the control plots. It is concluded that high yields and enhanced quality tubers can only be sustained through the application of o ptimal nutrient doses in balanced proportion.