Two field experiments were carried out during two successive summer seasons of 2009 and 2010 at the experimental farm, El-Kassasein Research Station, Ismailia Governorate, to investigate the effect of different rates of nitrogen and potassium fertilization (100%, 75% and 50% of the recommended dose) and foliar application with urea and citrate potassium at  rates of 0.05 and 1 % and their interactions on plant growth, fresh and dry weight, yield and its components and chemical constituents of Jerusalem artichoke plants (Helianthus  tuberosus  L.) cv. fuseau under sandy soil conditions. Fertilization with 100% of nitrogen and potassium from the recommended dose recorded maximum values of plant height, number of shoots / plant both fresh and dry weight/plants, yield and its components, and chemical constituents of tubers in both seasons. Spraying Jerusalem artichoke plants with urea  and citrate potassium at a rate of 1% significantly increased plant growth, yield and its components as well as chemical constituents of tubers. In general, the best interaction treatment among different rates of nitrogen and potassium fertilization and foliar application with urea and citrate potassium was fertilization with 100% of the recommended dose and foliar application with urea and citrate potassium at a rate of 1% as compared with other treatments.