Effect of agrometeorological parameters on the phenology of pollen emission and production of olive trees (Olea europea L.)

The pollination period and pollen concentration of olive trees (Olea europea L.) and olive production were analysed for Prato and Florence using a data set of 8 years (1991-1998). Meteorological data have been used to obtain information about weather conditions during vegetative seasons and correlations were found both for the phenology and yield. The results showed that air temperature previous to the onset of flowering is of great importance in determining the reproductive cycle of olive tree but the chill period in January and February should also be considered. Olive pollen collected during the pollination period was positively correlated with the production level for both sites. Weather condition following pollination were also taken into account for a better assessment of the final yield. Abbreviations: CV - Coefficient of Variation, is the percentage ratio of standard deviation and the mean; GDD - Growing Degree Day was calculated starting from 1st January using 5 degree C as threshold temperature; DOY - Day Of Year; MPA - Main Peak Appearance date; MPP - Main Pollination Period, the days of the year when the pollen collected is included between 5% and 95% of annual total; DOY MPP - DOY when MPP starts; ND - Number of Days; STDD - Standard Deviation in Days, is the ratio of standard deviation and average daily accumulation of the stage; SPI - Seasonal Pollen Index, daily pollen concentration from the beginning to the end of MPP; r super(2) - Determination Coefficient (* = P < 0.05, ** = P < 0.01, *** = P < 0.001).