Foliar application of bio-fertilizers influenced the endogenous concentrations of phytohormones and amino acids in leaves and roots of olive trees (Olea europaea L. cv. Chemlali)

The chemical composition of olive leaves and roots of Chemlali variety was evaluated regarding the contents of amino acids and endogenous phytohormones under foliar application of biofertilizers (F1: rich in nitrogen (N), phosphorus (P), potassium (K); F2: rich in calcium (Ca); F3: application of F1 and F2). The results of this study demonstrated significant effects of tested fertilizers on the concentrations of amino acids. Glutamic acid and asparagine had the highest concentrations in leaves and the lowest concentrations in roots under F1 and F3. Regarding the concentrations of endogenous phytohormones, high contents of indole-3-acetic acid and salicylic acid were found in leaves and roots under the application of F1 biofertilizer. Jasmonic acid (JA) was of higher concentration in root than leaves, while abscisic acid occurred in lower concentration. Moreover, the analysis of isoprenoid cytokinins by ultra-performance liquid-chromatography tandem mass spectrometry (UPLC-MS/MS) showed that these cytokinins were improved and became more abundant in roots under foliar treatments. Particularly, Zeatin-N7-glucoside and Dihydrozeatin-N9-Glucoside were enhanced under F1 and F3. The results of this study suggest that foliar application of biological fertilizers may improve physiological status of olive trees throughout the enhancement of some phytohormones and amino acids. Key words: Foliar fertilization, olive trees, amino acids, indole-3-acetic acid, isoprenoid cytokinins.