Olive oleic acid proportion is influenced by different dimensions of the daily temperature oscillation, especially night temperature.

GARCIA-INZA, G. P.; HALL, A. J; ROUSSEAUX, M. C.

Split

Congreso; The Eight International Symposium on Olive Growing (ISHS); 2016

International Society of Horticultural Science

The proportions of individual fatty acids in olive oil are influenced by environmental variables, such as ambienttemperatures between flowering and harvest. Mean daily temperature has been shown to have anegative effect on the proportion of oleic acid in the oil. Under naturalconditions or in experiments in which mean daily temperatures are manipulated insuch a way that the natural daily oscillation in temperature is followed, mean dailymaximum and minimum temperatures covary with mean daily temperature. The objective of this study was to assesschanges in oleic acid content andtheir association with different dimensions of the thermalregime (mean daily temperature, and mean daily minimum and maximum temperatures) experiencedby the fruit duringits growth. Five branch-leveltemperature treatments were applied: a control (T0) thatfollowed the daily dynamics of ambient temperature,two levels of daytime (8-20h) heating thatincreased temperature 5 and 10 °Crelative to T0 duringthe day, and two levels of nighttime (20-8h) heating to 5 and 10 °Cmore than T0. Treatments were applied usingtransparent chambers with individualized temperature control to fruitingbranches of trees (cultivar Arauco). The fruiting branches were treated for 77days during the oil accumulation phase. The treatments successfully altered the normal course of the daily temperature regime, and achieved a broad range in mean daily temperature (<6 °C) whichcovered the natural range of thisvariable for the region. The proportion of oleic acid showed a significantnegative association with the increasein mean minimum (nightime) temperature(R2 = 0.45) and withmean daily temperature (R2=0.32), but was not significantlyassociated with mean maximum temperature. Inolive, as in sunflower, night temperatures have an important role incontrolling the proportion of oleic acid in the oil.