Changes in Volatiles of Olive Tree Olea europaea According to Season and Foliar Fertilization

In the present study, four foliar fertilizers (FF1, FF2, FF3 and FF4) were separately sprayed on Chemlali olive trees at different moments of the vegetative cycle. FF1 (rich in nitrogen) was applied during the vegetation stage (Last January-February) at a dose of 5 L/ha per spray (three sprays per season). FF2 (rich in boron, magnesium and sulphur), FF3 (rich in phosphorus and potassium) and FF4 (rich in phosphorus and calcium) were applied respectively during the stages of flowering (Last March-April), fruit growth (July-August) and ripening (October-November), at a dose of 3 L/ha per spray (three sprays per season for each fertilizer). The volatile fraction was analysed by GC-MS, 46 volatile compounds were identified and their amount were expressed as relative abundance (%). In a general view, the most abundant volatiles in Chemlali olive leaves across the vegetative cycle were (E)-2-hexenal, nonanal, (E)-beta-damascenone, 3-ethenyl pyridine and beta-caryophyllene. The levels of these main compounds and the general composition of the volatile fraction varied significantly through season. The volatile levels were mainly affected by the two foliar fertilizers enriched with nitrogen and Boron respectively. The most affected volatiles were (E)-2-hexenal, nonanal, 3-ethenyl pyridine, (E, E)-alpha-farnesene, and (E)-nerolidol. Less impact was noticed after the use of the other foliar fertilizers. Our study is the first investigation bringing data about the variation of leaf volatile profile of Chemlali cultivar across a vegetative cycle and showing the impact of nutrient foliar sprays on olive leaf volatiles. (C) 2017 Friends Science Publishers