Olive tree

Description
Olive trees are a typical mediterranean species. Olive trees are one of the oldest trees used for agricultural purposes. They can grow up to 15 m of height and can reach a lifespan of more than a thousand years. They started being used in our region in the 4. century AC and were brought here by greek colonists. The coastline of the north Adrian along with a few Italic regions is the farthest north border where it is possible to cultivate large fields of olive trees. In Slovenia the olive trees are grown from the coastline to the Kranian border ( Istra region), in the Goriška brda, in the Goriška region and in some places of the Vipavska valley. The olive plantations are relatively small, mostly from 0.2 to 3 hectares large ( from 0.4942 to 7.413 acre)

Olive trees are periwinkle and have a three year long leaf cycle. the leafs are plain, oppositely placed, shaped in a stretched oval-like shape with a small stem. The upper side of the leaf is green and  has a glimmer to it, while the bottom side is silvery grey coloured. Around 10-45 blooms are joined together which grow in the leafs of the sprout. They are a hermaphrodite blossom and are 15 mm to 60 mm big and white coloured. Olive trees  transfer spores by air. The olives have a pit, are of different sizes, shapes and colours (from dark green to purple and black) The olives differ depending on the type of olive tree and growth conditions. The weight of an olive is from 1 g to 10 g. The green skin protects the meat of the olive, while the meat protects the seed. In ripe the meat represents 60-90 %, pit 10-40 %, and the seed only 2 % of the olive. We reproduce olive trees with green cuttings or with cutting a part of the tree and planting it. We plant them somewhere between March and April and harvest them in between October and November depending on the variety.

Growth conditions and habitat
The most suitable temperature for growth is from 20 to 30 °C, the trees can survive 40-50 °C. In winter they can survive temperatures as low as -6 to -7 °C for a short amount of time (few days at most). The trees grow in regions with 300 to more than 1000 mm of yearly rain. They require a lot of sunlight, so when planting them, we look for sunny spots, big enough planting distances and a suitable Cultivable form.  Olive trees with sunlight grow bigger olives, bigger oil concentration and equalized ripening. On the other hand the trees are well adapted to different kinds of soil. But it favors light soil with high porousness and soils that are rich with neutral and slightly acidic reactions. In heavy clay soils the porousness is small and can lead to the soil holding large amounts of water, which are not suited for olive trees. In shallow and poor soils the trees also bear less olives. The presence of limestone is very crucial. Calcium carbonate is said to affect the resistance of olive trees to the cold and the quality of oil.

Culinary use
From olives we can produce virgin olive oil exclusively with mechanised procedures. Olive oil is great for cardiovascular diseases, helping the heart, lowering the oxidative stress and helps the blood lipids. So if we want to gain as much health benefit from olive oil we must keep it and use it with low temperature. We can use it for baking at the risk of losing its healing properties.

Istrska belica: A plant of unknown origin speculated to originate from Beljunec in the outskirts of Trieste. Semi-lush, closed, upward and broom-like growth, a relatively later entry into fertility . Self-adhesive variety, but better results are gained when in a mixed plantation. It blooms rather late in the second half of November. The fruits are medium size, yellow and green coloured which transitions to a reddish or pitch black colour. It is known for high quantities of oil. The oil is fresh, bitter and spicy.

Štorta: Meant to be put in storage jars. The trees are quite lush and very rare and the fertility of the trees is regular and comparably good. It bloom early, The fruits are medium or large size, elongated shape and slightly curved. It is known for the colouring to star on top, so half of the fruit is still green while the other part has already darkened.

Sources:
Vesel Viljenka and coworkers: Olive tree. Farmers voice, Ljubljana, 2009:
https://prehrana.si/clanek/152-ali-se-oljcno-olje-lahko-segreva?gclid=Cj0KCQjwpcLZBRCnARIsAMPBgF0UGm0hAq76XBCJAWJ5CAoPBdtOxdv4s2hnXC5UlTvcnVLZfbJ7I7IaApFuEALw_wcB