The olive cultivar ‘Picual’ is an optimal pollen donor for ‘Barnea’

Abstract

Some olive (Olea europaea L.) cultivars are almost completely self-incompatible. The aim of this study was to determine the optimal pollen donors for the olive cultivar ‘Barnea’. The study was carried out during two consecutive years and was based on artificial cross-pollination as well as molecular paternity analysis of ‘Barnea’ fruits sampled from commercial olive orchards. We assessed the dates and duration of the flowering of 11 commercial olive cultivars to determine each cultivar's optimal period of effective cross-pollination. Artificial cross-pollination of ‘Barnea’ flowers with the donors ‘Picual’, ‘Coratina’ and ‘Askal’ showed fruit set rates similar to those obtained in open-pollination. ‘Arbequina’ showed a much lower fruit set rate and self-pollination of ‘Barnea’ proved it to be close to self-incompatible under our conditions. The stigma was found to be receptive to pollen during the first four days after anthesis. Self pollination resulted in germination of the pollen grains on the stigma. However, the pollen tubes were significantly shorter than the ones resulting from cross-pollination. Based on molecular paternity analysis, only three seeds out of 202 analyzed ‘Barnea’ fruits, sampled from commercial orchards, were found to be the product of self-pollination. ‘Picual’ was identified as the most frequent pollinator of ‘Barnea’ trees in commercial olive orchards, even when located further away from the ‘Barnea’ trees than various other cultivars.The cv. ‘Picual’ has been tentatively identified as a superior pollinator of the cv. ‘Barnea’ based on several parameters, leading us to suggest that the yield of ‘Barnea’ may improve if there are ‘Picual’ trees present upwind to their location in the olive plantation.