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Foliar fertilization in rain-fed olive orchards is used nowadays in order to improve the yields for the olive oil industry. The present work aimed to study the effect of foliar fertilization on the quality parameters of olive fruits. Three foliar fertilizers and biostimulants were applied on Chemlali olive cultivar, cultivated under rain-fed conditions in the center of Tunisia, at different stages from the vegetative cycle during two successive years. Six treatments formed the fertilization program: F1 (rich in nitrogen), F2 (rich in boron), F4 (a biostimulant rich in calcium), F3 (supplying an addition of F1 and F2), F5 (supplying an addition of F1, F2 and F4) and a control (without foliar fertilization). At the end of the experiment during the year 2015, fruits were harvested, freeze-dried and the characteristics of drupes and chemical composition of the fruits were evaluated: mineral composition, carbohydrates profile and individual polyphenols. Results showed that some treatments especially rich in Ca improved the fruit size. Foliar fertilization induced differences in the mineral content of fruits. Regarding carbohydrates, glucose was the main sugar present in the fruits and varied between 8.8 μg/mg dry weight (d.w) and 36.43 μg/mg (d.w.). Changes were clearly observed in the pool of the phenolic fraction. The combined treatment F5 showed the highest concentrations in oleuropein and hydroxytyrosol and were equal to 742.6 and 112.94 μg/g of fresh weight respectively. This work is of great interest because it showed the role of nutrients supply in improving the quality of olive fruits. [ABSTRACT FROM AUTHOR]

Growth and biochemical parameters of leaves, flower buds and flowers of olive (Olea europaea L. cv. Chemlali) treated by foliar biofertilization (T0: untreated trees; T1: rich in nitrogen (N), phosphorus (P), potassium (K); T2: rich in calcium (Ca); T3: application of T1 and T2) were analyzed during the flowering stage. The results showed that T1 resulted in higher contents of leaf N, K, and Na. T1 and T3 resulted in an increase of pigment concentration in leaves. All foliar treatments affected negatively the contents of total polyphenols and orthodiphenols in leaves and flower buds. Lower amounts of individual phenolic compounds were detected in the leaves under all foliar bio-fertilizations and in flower buds of olive trees sprayed with T2 and T3. This decrease is explained by the lower enzymatic activity of L-phenylalanine ammonia-lyase. In flowers, T1 exhibits the highest levels of total polyphenols, o-diphenols, and individual phenolic compounds compared to T0. [ABSTRACT FROM AUTHOR]

Growth and biochemical parameters of leaves, flower buds and flowers of olive (Olea europaea L. cv. Chemlali) treated by foliar biofertilization (T0: untreated trees; T1: rich in nitrogen (N), phosphorus (P), potassium (K); T2: rich in calcium (Ca); T3: application of T1 and T2) were analyzed during the flowering stage. The results showed that T1 resulted in higher contents of leaf N, K, and Na. T1 and T3 resulted in an increase of pigment concentration in leaves. All foliar treatments affected negatively the contents of total polyphenols and orthodiphenols in leaves and flower buds. Lower amounts of individual phenolic compounds were detected in the leaves under all foliar bio-fertilizations and in flower buds of olive trees sprayed with T2 and T3. This decrease is explained by the lower enzymatic activity of L-phenylalanine ammonia-lyase. In flowers, T1 exhibits the highest levels of total polyphenols, o-diphenols, and individual phenolic compounds compared to T0. [ABSTRACT FROM AUTHOR]

The present research was accomplished on olive fruits cv. Picholine. It aimed to study the effects of nutrient fertilization on mineral elements, phenolics, tocopherols and soluble carbohydrates. The foliar applications were carried out during two successive years and included four treatments: TC (control, without foliar nutrition), T1 (rich in nitrogen, applied at the start of vegetation, 10 days later and 20 days later), T2 (rich in boron, magnesium, sulfur and manganese, applied at the beginning of flowering and 10 days later) and T3 (T1 + T2). At the end of the experiment (after two experimental years), olive fruits were analyzed. This study showed that fertilization caused a significant decrease of total phenols and tocopherols contents and induced qualitative changes in the profiles of minerals, phenols, tocopherols and carbohydrates. The results elucidated an evident association between environmental concentrations of nutrients and chemical composition of olive fruits. [ABSTRACT FROM AUTHOR]