Critical fruit developmental periods influencing oil quality in olive (cv. Arbequina) under reduced solar radiation

The global expansion of olive cultivation has led to the widespread adoption of highly mechanized production systems, with the Arbequina cultivar emerging as a dominant choice due to its high productivity and adaptability. Given that the physicochemical quality of its oil is highly sensitive to environmental conditions, understanding the impact of abiotic stress on olive oil quality during key fruit developmental stages is essential for adapting orchard management to climate variability. In this context, the aim of this study was to identify and characterize the critical periods of fruit development that determine the physicochemical quality, fatty acid composition, and phenolic profile of ‘Arbequina’ olive oil under conditions of reduced solar radiation. To this end, whole olive trees were subjected, to intense shading (80%) during 30-day periods, using chambers. The results revealed that oil composition, particularly oleic acid content, and extinction coefficients are significantly influenced by the timing of stress exposure. Besides, two key accumulation phases of the principal fatty acid, cis-oleic acid were identified: an early phase (30–60 days after full bloom, DAFB) marked by increased content, and a later phase (120 DAFB) showing a pronounced decline. These changes were inversely correlated with palmitic acid levels. Linoleic acid levels decreased significantly during the 30–60 DAFB, while linolenic acid levels declined between full bloom and 30 DAFB, followed by an increase after 90 DAFB. Regarding phenolic compounds, oleacein and oleocanthal levels decreased significantly under stress, whereas hydroxytyrosol and luteolin remained stable, indicating selective metabolic responses. Given the global expansion of olive cultivation in semi-arid regions, these findings provide a framework to mitigate climate-induced quality losses in a wide variety of emerging production areas. By identifying stress-sensitive developmental stages, this study offers actionable insights to preserve EVOO quality and optimize harvest and canopy management.