Olea phenology and its relationship with the local and regional pollen patterns.

LATORRE, F. & BELMONTE, J.

Switzerland

Congreso; 8th International Congress on Aerobiology; 2006

The Swiss Society for Aerobiology. MeteoSwiss and the National pollen monitoring network. The University of Neuchâtel. The International Association for Aerobiology.

Introduction In order to contribute to a better knowledge of the reproductive phenology of Olea europaea L. and the pollen production, emission and dispersion, the preliminary results obtained in 3 parcels of an olive cultivation in Cambrils (Tarragona, North East Spain) during 2003 are presented. Methods Methods The parcels were visited at least once a week. The flowering and fruit production was studied in 30 trees (10/parcel) using a 1 to 7 phenologic scale. Other 12 trees (4/parcel) were selected and analysed more precisely, counting the number of buds, flowers and fruits in 144 selected inflorescences (3/branch) in 48 selected branches (4/tree). The Olea pollen concentration in the air was obtained by means of Hirst traps. A seven-day pollen recorder located at a height of 15 m. provided the regional pollen levels and two portable Hirst traps located temporally inside the cultivations at a height of 1 m. provided local pollen counts. Correlation and stepwise regression analysis between pollen, flowering and meteorological data were done. Results and conclusions The 3 parcels showed similar flowering curves (differences under 15%). The flowering period (phenophases 2-6) extended from 9-27 May. Phenophases 3-5 (pollen emission) occurred in only 10 days (13-23 May). Maximum flowering was observed in 13 and 16 May, depending on the parcel. The number of buds/inflorescence varied from 9-33. An important drop of fruits occurred and at the harvest moment (31 October) there was only 1 fruit/inflorescence (range 0-5), that is a lost of 82-96% with respect to the number of pollinated flowers. The maximum number of fruits was found in the inflorescences with an intermediate number of buds. There were no differences in productivity regarding the situation of the inflorescence in the branch. The maximum hourly Olea pollen concentration at 15 m. was recorded on 20th May (6707 p/m³) at 12 AM. At 1 m. and inside the parcels the highest concentrations were 2.5 times higher and occurred in 13 May (21909 p/m³), 16 May (8484 p/m³) and 20 May (20248 p/m³), respectively. There is a direct relation between the quantity of emission sources and the pollen emitted inside the parcel (r=0.98 p<0.05). The pollen production in the parcel with more trees coincides notably with the pollen curve at 15 m. At a local scale, pollen depends significantly only on the flowering stage (p=0.001, R²=92%). In the regional scale, pollen depends on the flowering stage (p=0.00007), but also on the maximum temperature (p=0.01, R2=87%).