Olive trees are pollinated when the pollen is released from the flowers and transported from one plant to another. In some cases, a tree may also self-fertilise.
The process of pollination is vital for the life cycle of most plants and occurs with the help of atmospheric agents (usually wind) and the impeccable work of pollinating insects, birds and also bats. It is this magic that regulates the earth’s flora allowing us all to survive.
The majority of olive pollination occurs thanks to the wind in a process known as anemophily. Surprisingly, the wind can take pollen huge distances – up to 1,000km, but it’s much more probable that the pollen arrives on a stigma far more swiftly than that.
This type of pollination is important because it facilitates cross-pollination, where a plant’s flowers are fertilized by another plant’s pollen, leading to more genetic variability (biodiversity), allowing the plant to adapt and change. Some research suggests that cross-pollination in olive groves may increase the yield and even improve fruit quality, but the jury is still out and it may in any case only apply to certain cultivars.
Insect Pollination (Endogamy)
Entomophilous pollination occurs thanks to insects and other air-borne species. Whilst in search of the flower’s nectar, pollen can often stick to the insect’s body – bees are particularly good at this because the tiny hairs on their body can capture large amounts of pollen. As the insect travels from flower to flower, it releases the pollen grains and if the pollen arrives at the flower’s stigma, pollination occurs.
As we are forever mentioning, there are many different olive cultivars out there – some have the capacity to self-pollinate and others require pollen to arrive from different cultivars to allow fertilisation to occur, so growers need to set up an environment that can successfully encourage pollination.
There are different types of pollinators
Self-pollinating Olive Cultivars
The pollen produced by the stamen can drop down onto the pistil’s stigma. This means that the tree can produce fruit without the assistance of wind or insects. Self-pollinating cultivars include Arbequina, Frantoio, Coratina and Koroneiki.
Self-incompatible Olive Cultivars
A significant amount of olive cultivars are self-incompatible, so they require the pollen of other cultivars in order to pollinate. This is believed to be nature’s way of promoting genetic variability and evolutionary diversification. Self-incompatible olive cultivars that can be pollinated by other cultivars include Leccino, Nocellara del Belice, Moraiolo and Peranzana.
Some self-incompatible olive trees however can only be pollinated by specific olive cultivars. These include Tonda Iblea, Correggiolo and Ascolana Tenera.
The work behind exceptional olive oil is profound. Nature takes care of a large part, but growers who are attentive to pollination, introducing beehives in or near the grove and considering which cultivars to plant can certainly influence the outcome.