Elevated temperature affects vegetative growth and fruit oil concentration in olive trees (Olea europaea)

Abstract

Temperature is one of the main factors that regulates the growth and development of crops and determines their yield. In recent decades, there has been an increase in global temperature, which represents a challenge for olive production. Olive trees in Argentina are grown over a wide range of latitude and altitude, and it has been observed in warmer areas of the country that some cultivars have lower yields and greater vegetative growth than in their regions of origin in the Mediterranean Basin. Thus, the aim of this study was to evaluate the effect of elevated temperature on the vegetative growth and fruit oil concentration of two olive (Olea europaea) cultivars by directly manipulating temperature. The experiment was conducted at an experimental station in the province of La Rioja in northwest Argentina. Two temperature levels (a control and a heated treatment; 3 °C above the control) were applied from fruit set until final harvest using open top chambers (OTC) with electronically controlled heating systems. The responses after one season of treatment for potted ‘Coratina’ and ‘Arbequina’ trees are shown here. Whole tree leaf area was significantly greater in the heated OTC than in the control OTC for both cultivars. Shoot elongation showed a similar tendency, but the apparent difference was not statistically significant. In contrast, elevated temperature had a negative effect on fruit dry weight and oil concentration in both cultivars. Elevated temperature reduced fruit dry weight by 0.34 and 0.22 g in ‘Coratina’ and ‘Arbequina’, respectively. Additionally, fruit oil concentration (%) was 4.6 and 6.2 % less on a dry weight basis in fruit that received elevated temperatures. The results indicate that elevated temperature promotes vegetative growth and negatively affects oil concentration in olive trees under our climate conditions.