Use of exogenous salicylic acid in the preharvest treatment of olive tree to enrich olive fruits in antioxidants

We here study the effect of the preharvest application of salicylic acid at two different concentrations on the olive fruit phenolic composition. Influence of the olive cultivar and harvesting day were considered. As a result, the total phenol content increased significantly in olive fruit, particularly when using 200 mg mL^‑1 of salicylic acid. However, the free radical scavenging activity was olive cultivar dependent. For instance, when 200 mg mL^‑1 salicylic acid was applied to olive trees, the antioxidant content decreased from 161 to 278 µg mL^‑1 for ‘Arbequina’ fruit after 3 days of treatment, whereas it increased from 397 to 258 µg mL^‑1 for ‘Picual’ fruit. Generally speaking, oleuropein and hydroxytyrosol contents enhanced in olive fruits with the application of 200 mg mL^‑1 of salicylic acid. The results found suggest that exogenous salicylic acid is an interesting agronomic practice to enrich olive fruits in antioxidants.