Flowering time of eleven olive cultivars in a high-density orchard in central Italy

Time of flowering in self-incompatible cultivars should extensively overlap for an effective cross-pollination in olive orchards. This factor becomes pivotal with increasing tree density in wide mono-cultivar blocks. The study considered different positions of the inflorescences in the canopy and along the mixed shoot, in order to check the presence of flowering gradients. The measurements were carried out in 2014 in a young high-density olive orchard (1,250 trees ha-1) located in Marche Region (central Italy) on 11 cultivars (‘Arbequina’, ‘Ascolana dura’, ‘Piantone di Mogliano’, ‘Piantone di Falerone’, ‘Rosciola’, ‘Rosciola Colli Esini’, ‘Maurino’, ‘Coroncina’, ‘Carboncella’, ‘Lea’ and ‘Nostrale di Rigali’) using the BBCH scale. Two one-year-old mixed shoots with average length and nodes were selected in early May in the apical and basal position of the canopy respectively on five trees per cultivar (total: 10 shoots per cultivar). ‘Ascolana dura’ and ‘Arbequina’ showed a high number of inflorescences in the basal and distal portions of the mixed shoot, respectively. In ‘Lea’ and ‘Ascolana dura’ high percentage of sterile flowers was recorded. Along the mixed shoot, the anthesis started from the median and distal inflorescences for all the studied cultivars. We can assume that the median-distal inflorescences had a favourite position compared to those in the basal portion. The flowering phenogram of the 11 olive cultivars highlighted a good bloom overlapping. The full bloom was early in ‘Maurino’ (which only partially overlaps with the next group), intermediate in ‘Rosciola’, ‘Nostrale di Rigali’, ‘Coroncina’, ‘Carboncella’, ‘Piantone di Mogliano’ and ‘Arbequina’ and late in ‘Ascolana dura’, ‘Rosciola Colli Esini’, ‘Piantone di Falerone’ and ‘Lea’. Results presented in this study provide helpful information on how to combine cultivars in order to enhance cross-pollination in high-density olive orchards.