Yield and chemical composition of 'Piarom' Date-Palm Phoenix dactylifera as affected by nitrogen and phosphorus levels

Extraordinary importance of Date-Palm, Phoenix dactylifera especially ‘Piarom’ variety and also undeniable effect of nitrogen and phosphorus on yield and quality of this product, caused this research to be accomplished. The research was performed during two years on 72 (4*3*3*2=72 trees) fruitful, 12 years old trees in Hormozgan province. Treatments were consisted of four levels of nitrogen (0, 350, 700 and 1050 grams tree-1) and three levels of phosphorous (0, 300 and 600 grams tree-1) with three replications. Sources of nitrogen and phosphorus were urea and triple super phosphate (TSP), respectively. This experiment was accomplished in a factorial manner and in a randomized complete blocks design. Fruit thinning was done in a ratio of eight leaves to one cluster. Irrigation was done through drip system and pollination according to the custom of the region. After harvesting, some plant parameters such as production yield, concentration of essential elements in leaves, average of fruit weight, reducing sugar percentage in fruits, fruit Brix and the weight ratio of fruit pulp to it's stone were determined. Results showed that nitrogen levels caused significant variations in many considered parameters but not in concentration of copper, zinc and manganese in leaves. The effect of phosphorus levels on all plant responses was meaningful except for concentration of nitrogen, zinc, copper and manganese in leaves. Furthermore, interaction of nitrogen and phosphorus was meaningful in some cases.