Relationship between flowering and heat units to analyze crop efficiency of olive cultivars located in southern Italy

Abstract

The relationship between heat units trends and reproductive development in olive (Olea europaea, L.) was studied over a 3-year period (1999-2001) in 15 areas in the southern Italian regions of Campania, Calabria, Puglia, and Sicily. Heat units were calculated using GDH and GDD formulas and the flowering phases in the olive groves were studied using volumetric pollen traps that aspirate fixed quantities of air. With this method, the olive pollen release and flowering trends were determined. The main objective of the study was to correlate the spring heat unit amounts and the phases of maximum pollen emission with the date of flowering. Moreover, the ranges of GDH and GDD in the different study areas were calculated to identify maps of olive pollen release.