Response of oil accumulation dynamics to elevated temperature in olive fruit (Olea europaea)

Abstract

Olive crop expansion to new, warmer growing regions and climate change have reinforced the need for manipulative field experiments to better understand the physiological responses to elevated temperature. Thus, the aim of this study was to evaluate the response of oil accumulation dynamics including accumulation rate, duration, and maximum oil concentration to a moderate temperature increase in young trees of two cultivars (?Arbequina?, ?Coratina?). Two- or three-years-old potted trees were actively warmed by 3-4 °C from final fruit set to the end of the oil accumulation phase (December to early May) in one season using open top chambers under outdoor conditions or grown at near-ambient temperature in similar control chambers. Oil accumulation dynamics were determined from successive fruit samplings. Oil concentration was determined on a dry weight basis by nuclear magnetic resonance. Fruit oil accumulation dynamics were explained by a bi-linear function. In both cultivars, the sustained warming reduced the final oil concentration due to a strong reduction in oil accumulation rate (% day-1), while the duration of the oil accumulation period (in days) was unaffected. In a similar manner, the decrease in final fruit dry weight in response to warming was associated with reductions in fruit growth rate (g day-1) and generally not the duration of fruit growth. As a result, oil content per fruit (g fruit-1) was severely reduced by warming. These insights should be considered to improve current predictive models of climate change impact on olive production.