Inflorescence characteristics and pollination compatibility of two local olive cultivars in high-density plantation

The self-fertilization and the cross-fertilization rate represent important factors in determining the suitability of local olive varieties to the high-density plantation. The inflorescence and flowering features, and the fruit set were investigated in 2016 (OFF year) for ‘Piantone di Mogliano’ (PM) and ‘Piantone di Falerone’ (PF), two promising local cultivars, in a young high-density olive orchard (1,250 trees ha-1) located in Maiolati Spontini (central Italy) with controlled pollination. Piantone di Falerone showed a higher percentage of open flowers compared to Piantone di Mogliano at the same date (June 3). The fruit set was determined under self-, cross- (PM×PF and PF×PM) and free-pollination conditions on small fruiting branches. The self- and cross-fertilization rate was tested closing the branches in paper bags before flowering onset. ‘Piantone di Falerone’ showed a higher number of inflorescences (positively correlated with the number of ramifications per fruiting branch) and a lower number of flowers per inflorescence compared to ‘Piantone di Mogliano’ so that finally no significant differences were recorded on the total number of flowers per fruiting branch in the two tested cultivars. ‘Piantone di Mogliano’ showed a lower number of perfect flowers due to a higher percentage of male flowers (ovary abortion) compared to ‘Piantone di Falerone’. According to fruit set, ‘Piantone di Falerone’ resulted self-sterile (no fruit set in paper bags with self-pollination) and ‘Piantone di Mogliano’ partially self-compatible. No differences on fruit set were recorded between the cultivars in free-pollination conditions (p=0.26), whereas in cross-pollination condition, inside paper bags, the combination PM×PF resulted in a higher (p=0.004) fruit set compared to the PF×PM one. Present results provide helpful information on the characteristics of the inflorescence, flowering time and self and non-self-fertility of ‘Piantone di Mogliano’ and ‘Piantone di Falerone’ and suggest the use of other cultivars as pollinators to increase fruit set in free pollination conditions.