The effective pollination period of the olive cultivar ‘Arbequina’ (Olea europaea L.) in a non-traditional production region

Abstract

• ‘Arbequina’ is self-incompatible and fully compatible with ‘Coratina’. • The EPP was estimated to be at least seven days by different methodologies. • The EPP is not a limiting factor for ‘Arbequina’ in Uruguay. In non-traditional production regions, olive cultivation is facing challenges sometimes associated with poor fruit set. That is the case of Uruguay, where olive cultivation has reached 7000-planted hectares; however, yields are low and irregular. Uruguay has a temperate climate with particular characteristics that differentiate it from the Mediterranean basin. It presents greater annual rainfall, reaching up to 1600 mm, high relative humidity and high interannual variability in the rainfall and thermal regime. We hypothesized that these environmental conditions may affect the reproductive biology of olive trees, reduce their Effective Pollination Period (EPP) and limit fruit set. For this reason, we determined the EPP for ‘Arbequina’, the main olive cultivar in Uruguay, by two methodologies: sequential pollination of flowers of different ages, and analysis of its components (stigmatic receptivity, ovule viability, and pollen tube growth). We determined the EPP to be of at least 7 days with both methods. Stigmatic receptivity, assessed by the ability to support pollen adhesion and germination, was maintained for at least 20 days after anthesis. More than 50% of the evaluated flowers maintained at least one viable ovule 23 days after anthesis, and pollen tubes required between two and three days to reach an ovule. No differences in pollen tube growth were found in relation to the age of the pistil. Our results indicate that a short EPP is not behind the low yields of ‘Arbequina’ in Uruguay.