Flower and pollen production in the 'Cornicabra' olive (Olea europaea L.) cultivar and the influence of environmental factors

The olive pollen production showed a variation related to temperature and rainfall during dormancy period. A correlation was found between the number of olive tree inflorescences and airborne pollen counts. Analysis of pollen production in crops such as the olive is of particular agronomical value, in that it can help to predict final harvest outcomes. Since olive pollen is a major cause of allergy in the Mediterranean region, this analysis can also provide health-related benefits. The present study analyzed flower and pollen production in 'Cornicabra' olive cultivar, charting its correlation with airborne pollen counts, with phenological findings such as onset of pre-flowering period, and with environmental factors such as temperature and rainfall, elevation and northern vs. southern exposure of floral structures on the tree crown. Findings confirmed spatiotemporal variations for most of the parameters studied. Mean pollen grain production per flower of olive tree was 1.10 x 10(5) +/- A 0.25 x 10(5). Variations in the production of flowering branches, inflorescences, flowers and pollen reflected internal regulation processes linked to alternate bearing as well as year-on-year variations in weather conditions. Temperature and rainfall during dormancy were the weather-related variables most influencing flower, inflorescence and flowering-branch production. Early attainment of chilling requirements during dormancy was associated with increased production, coinciding with earlier budburst. A correlation was found between the number of inflorescences-and thus overall flower production-and airborne pollen counts. Production parameters also varied as a function of olive grove location, although that variability was not clearly attributable to the elevation. The correlation between production parameters and northern vs. southern exposure on the olive tree crown was significant only for flowering branches, whose production varied depending on their location on the tree crown.