EFFECTS OF DIFFERENT NITROGEN, PHOSPHORUS, POTASSIUM RATES ON THE QUALITY AND QUANTITY OF CITRUS PLANTS, VARIETY THOMSON NOVEL UNDER RAINFED AND IRRIGATED CONDITIONS

Plants require nutrients including nitrogen (N), phosphorus (P), and potassium (K) for their growth and production. Although there have been previously extensive research work regarding the effects of NPK on plant growth, data related to the effects of long term application of NPK on the quality and quantity of citrus under rainfed and irrigated conditions are little. Accordingly, such effects were evaluated in this research work using different chemical fertilization factorially combined and on the basis of a completely randomized block design. Using ammonium sulfate (100, 150 and 200g tree (-) (1)), triple super phosphate (0, 25, 50, and 75g tree(-1)) and potassium sulfate (0, 50, 100, 150g tree (-) (1)) the quantity and quality of citrus fruit, variety Thomson were determined in a 10-year experiment in two different research stations in Ramsar, Iran. NPK fertilization significantly affected the quality and quantity of citrus fruits, indicating the significance of NPK fertilization for citrus production.