'Chemlali' olive trees in an irrigated grove: effects of tree age on virgin olive oil quality and mineral nutrient distribution in roots, leaves and fruits

Introduction. The effects of tree age on the quality of olive oil are not very clear. Data on the mineral element content in different plant organs of cv. Chemlali are also very scarce, and the correlation between tree age and mineral content is still unclear. Materials and methods. A two-year study was conducted on irrigated 'Chemlali' olive trees of two different ages (12 years old vs. 24 years old) in order to verify possible effects on either the nutritional balance in different plant organs (leaves, roots, fruits) or the virgin olive oil (VOO) quality. Results and discussion. The 24-year-old trees showed a higher mineral concentration with respect to 12-year-old trees in roots and fruits, whereas the opposite was reported for the leaves. Total phenols and induction time values were significantly lower in VOO from 24-year-old trees. Palmitic, palmitoleic, stearic and linoleic acid concentrations were higher in VOO of 24-year-old trees. Conclusion. These results can be useful in order to discriminate the characteristics of VOO obtained from trees of different ages and the mineral content data can be used for the optimization of the fertilization schedules with respect to the olive tree age for more sustainable management of olive groves.