Inoculation of arbuscular mycorrhizal fungi and application of micronized calcite to olive plant: Effects on some biochemical constituents of olive fruit and oil

• Olive fruits showed greater accumulation of hydroxytyrosol and p-hydroxybenzoic acid after mycorrhiza and calcite treated plants.
• Phenolics having hydrophilic structure were influenced more than those of lipophilic structure.
• Secoiridoid aglycones in the olive oils from mycorrhiza and calcite treated trees generally tend to decrease.

Some physico-chemical properties of olive fruits (Olea europaea L., variety ‘Sariulak’) and their corresponding oils during 2007–2013 crop seasons were investigated following inoculation with arbuscular mycorrhizal fungi (AMF, Rhizophagus intraradices) and application of micronized calcite (MC) [as plant growth stimulating product] with special emphasis on individual phenolic compounds.Olive fruits showed greater accumulation of hydroxytyrosol and p-hydroxybenzoic acid in plants on which AM was inoculated when compared to the values of uninoculated plants. AMF inoculation resulted in a reduction in vanillin, dimethyloleuropein and luteolin content of olive fruits. Secoiridoid aglycones in the olive oils from treated trees generally tend to decrease. There were differences in the levels of phenolics in fruits and their corresponding oils, such as the amount of hydroxytyrosol rose in AMF + MC applied fruits, nevertheless the amount of verbascoside, a secoiridoid conjugate of hydroxytyrosol, declined in the oil of AMF + MC treated plants.After the application of AMF + MC, the oils did not show a significant change in the total phenolics content contrarily to olive fruits. These results highlight that phenolic compounds having hydrophilic structure were influenced by AMF + MC application more than those of lipophilic structure.

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