Abstract

Young Arbequina olive trees, growing in North of Tunisia, planted under irrigated system, were selected to reasonable fertilization since 2006 of Nitrogen (N), phosphorus (P₂O₅) and potassium (K₂O) distributed according to the critical stage of development of the tree. This fertilization was reasoned on foliar, flower diagnosis and the exportation in fruits, leaves and woods. Olive leaves were sampled at the pit hardening stage, the standard period for leaf sampling during 2006, 2007 and 2008. Inflorescence samples were taken at petal whitening stage. These samples were done to assess the effect of reasonable fertilization on the nutritional status of the olive. The fruit was chosen at maturity stage to determine the effect of the combined fertilization on oil content, fruit weight, yield and mineral composition of fruit. After the three years of experiment, results showed an improvement of nutritional status of Arbequina olive tree in micro and macro nutrients as well in flower as in leaves subjected to reasonable fertilization. Significant differences of potassium in fruits were found, showing a better assimilation of K in olive tree that had received the combined fertilizer. Average weight of the fruit per tree, oil content and yield increased with NPK fertilizer. Further work is required to assess the just needs of the olive trees in fertilizers to minimize their environmental impact and improve crop quality and yield.

Key words: Olive tree, reasonable fertilization, nutritional status, mineral composition.