Effect of temperature during fruit growth on fruit dry mass, oil content and fatty acid composition in Olea europaea L. var ?Arauco?.

GARCIA-INZA, G. P.; CASTRO, D. N.; ROUSSEAUX, M. C.

Simposio; VIIth International Symposium on Olive Growing; 2012

Olive oil production has expanded because of the international increase in demand and the interest in its nutritional properties. In the northwest of Argentina (Catamarca and La Rioja provinces), olive crop represents the 70% of the planted area. In many instances, oil yield and oleic acid content are low in this warm region compared to values from the Mediterranean Basin. Thus, the objective of this study was to evaluate the effect of temperature as a controlling factor of fruit dry weight, oil concentration, and fatty acid composition. Four branch-level temperature treatments were applied using transparent plastic boxes with individualized temperature control to trees (var. ‘Arauco’) in a small, traditional orchard in Los Molinos, Argentina. The treatments included an ambient control, two heating treatments (5°C and 10°C higher than control), and a cooling treatment (5°C lower than control). The experiment was conducted from 30 days after pit hardening to the end of oil accumulation.  Mean temperature inside the boxes varied from 16°C to 32°C. Fruit dry weight was not affected by temperatures below 26°C, but greater temperatures reduced fruit weight. Oil yield and oleic acid content were negatively affected by increasing temperature. Oil content was reduced 1.1% per °C, while oleic acid content fell 0.7% per °C. These results suggest that elevated temperatures negatively affect oil quantity and quality in warm regions and that global change may reduce oil yields in olive.