Effective pollination period for ‘Manzanillo’ and ‘Picual’ olive trees

The effective pollination periods (EPP) for ‘Manzanillo’ and ‘Picual’ olive trees have been determined in two consecutive years in irrigated orchards in California and Spain. The duration of the EPP was variable between year and cultivar. Fruit set declined gradually in response to sequential cross-pollination. Consistent differences with respect to the maximum levels of initial fruit set occurred between 4 – 6 d after anthesis (DAA) in ‘Manzanillo’, and between 8 – 14 DAA in ‘Picual’. Fertilisation was first observed on day-2 after cross-pollination in both cultivars. Ovule longevity, determined by fluorescence microscopy, appeared to last > 14 d in both cultivars. The stigmas remained receptive for > 8 d. Estimates of the duration of the EPP, based on analyses of its components, were longer than those indicated by the declines observed in fruit set, suggesting that other factors such as the suitability of the style to support pollen tube growth may limit the duration of the EPP. These results suggest that self-incompatibility may be a more important factor than a short EPP in limiting fruit set in ‘Picual’, as well as in ‘Manzanillo’ olive trees.