Olive reproductive phenology along a latitudinal-altitudinal gradient in Argentinian growing regions

Abstract

Olive reproductive phenology is influenced by environmental factors including air temperature. Nevertheless, detailed information about olive phenology is scarce outside of the Mediterranean Basin. The aim of this study was to evaluate the effects of location, cultivar and year on two olive phenophases: reproductive budburst (BBCH53) and full flowering (BBCH65) at north and central western Argentinian growing regions. Phenological observations were taken weekly in seven olive cultivars at six locations along a latitudinal (29°-33°S) and altitudinal (450-1246 masl.) gradient during two growing seasons. The gradient had differences of up to 5.5°C for the mean temperature during winter and early spring (i.e. pre-flowering period). The dates for BBCH53 occurred over an extended time period of 70 days (August 6 to October 15) depending on the location x cultivar x year combination, while BBCH65 occurred over 38 days, starting on October 1. Significant differences between locations and cultivars were found for both phenophases. BBCH53 showed a delay at the lowest, more northerly latitude location relatively to the others, probably because of lower chilling accumulation. BBCH65 occurred earliest at the lowest latitude/altitude and the latest at the highest latitude. Location explained most of the variability in the dates for both phenophases, while cultivar accounted for about 6%. The duration of the period between BBCH53 and 65 was negatively related with the average air temperature during the same period. These results from an ample temperature range will be useful for modeling efforts.