Comparative Study of Fruit Maturation and Physicochemical Properties of Arbequina and Arbosana Olives under Intensive Cultivation in Tarhuna, Libya

Abstract

Identifying the correct time to harvest is vital to obtaining both quantity and quality virgin olive oil, especially for intensive HD growing systems. In this study, we investigated changes in the fruit ripening process and associated physical and chemical changes of two worldwide important HD cultivars, Arbequina and Arbosana, in a semi-arid environment in Tarhuna, Libya. Fruit was harvested weekly from veraison (mid-October) up to late maturity (late December) in the 2024/2025 growing season. The Internationally Accepted Maturity Index (MI), based on the color of the fruit skin as well as fruit weight, firmness, and oil quality (content and free acidity), was used. The results revealed a difference between cultivars’ ripening time and progression; Arbequina MIs progression was faster and reached its maturity earlier than Arbosana. High positive correlation was observed between MI and oil content (r > 0.92, p<0.01) and strong negative correlation between MI and firmness (r = - 0.81, p<0.01). While Arbequina is ready to be picked early, the latter (Arbosana) continued to gain oil over a longer time and achieved the maximal oil content (22 % dry matter basis). This study confirmed the MI as a useful, quantitative index for the optimal time for harvest in HD orchards under the local conditions of Libya; recommended an MI range between 3.5-4.5 and 4.0-5.0 for Arbequina and Arbosana, respectively, to obtain the best combination between oil quality and quantity.

Keywords: Maturity Index, Olea europaea L., Arbequina, Arbosana, High-Density Olive, Oil Quality, Tarhuna, Libya.