Study of the floral phenology of Olea europaea L. in Jaen province (SE Spain) and its relation with pollen emission

Phenological and aerobiological studies provide important information regarding the reproductive biology of cultivated species such as the olive. This article presents the results of an exploratory study of the floral phenology of Olea europaea L. at different altitudes in Jaen province (SE Spain) and an analysis of the main meteorological factors affecting flowering. As well, this study aimed to detect the relationship between phenology and olive pollen emission as a means of interpreting Olea pollen curves in the city of Jaen. Phenological observations were performed on olive trees at six sites, each at different altitudes and distributed over the whole area of olive cultivation in the province. Pollen data were obtained using a Hirst-type volumetric spore trap located within the city of Jaen. Phenological and aerobiological data were recorded in 2006 and 2007. This study shows that the chronology of the start of the flowering period depends on altitude. Statistical analyses indicate that the temperature, humidity, cumulative rainfall and cumulative solar radiation are the meteorological parameters that most affect olive floral phenology. The pollen season in Jaen generally lasts from May to June, with an annual total emission of over 40,000 pollen grains, the highest annual level of olive pollen emission in the world. The airborne pollen concentrations recorded in the city of Jaen are above all influenced by the olive groves located in the Guadalquivir valley.