Olive-tree
Basic Properties of the Tree
Olea europae is a modified species of the wild olive named Olea europaea L. oleaster, which is from the L. sativa olive family, and which is called “crazy olive” in our country.
Although the linguistic origin of the word olive is not known precisely; It is thought to derive from the word "zayit" in the Semitic language of Afro-Asian origin. As a linguistic origin, there is a consensus that it derives from the words "zait" in Hebrew, "ez-zeyt" and "zaitun" in Arabic, or "zeirtim" used by the Akkadians, one of the ancient tribes of Anatolia. There is an opinion that the "dt" (olive) sound in the Egyptian language originates from the northwestern Semitic language. The word "Zeyyat" is a word of Arabic origin that exists in Turkish, it is a male name, it is used in the sense of "the one who produces olive oil and olive oil", but its Arabic meaning is not related to olive oil, it is used in the sense of "abundance, abundance, increase" in Arabic. The Arabs lay "zeitun er-Rum" on old and large trees, even today. In ancient Crete, "elaiwa" comes from the Greek "elaia", the Latin "olea". The Romans preferred to call it "olive", while the peoples of western Europe preferred to call it "olive".
The wild species called "delice" in our country is a bush-like tree with an average height of four meters. Its grains are small, dark green in color, its fruit is not edible, and its oil content is low. But its trunk can be used for grafting application. In our country, the region where weeds are found in geographical terms is the Aegean Sea coast. It is interesting that even in the Eastern Mediterranean and Southern Near East, which is thought to be the geography where it was first domesticated in history, there are not so many wild olive trees. Weeds that grow spontaneously in nature can be removed and moved to another place. Grafting is used to shorten the fruiting period; The stem of the weed is inoculated with the human domesticated species L. sativa and begins to bear fruit earlier.
Olea europae L. sativa grows between 30-45 parallels to the north, usually on the sea coast, is delicate, slow-growing, requires labor to grow, but is quite long-lived, with good care and regular pruning, it has the capacity to produce hundreds of years. takes on appearance. It is a tree that varies between 2 and 10 meters in height, but can reach up to 15-20 meters. Its average life is 300-400 years. At the end of a productive life, its trunk dries up and the shoots that turn green from its roots can turn into a new tree. The 800-year-old olive tree, which was noticed to have roots when it was about to be cut into wood in Mersin in the mid-2010s in our country and was planted again, started to bear fruit after being grafted with a two-year-old sapling and after an intensive feeding and care process. There are three thousand years old olive trees, the most famous of which is on the island of Crete, known as the “ancient olive tree/ancestral tree”, and it still produces olives. Some of these trees, which are shown to be between 3000 and 3500 years old, are also available in Muğla and its surroundings in our country.
Botanically, there are about twenty olive species, the majority of the oil-producing subspecies in the Oleacea family are in the form of trees, shrubs and shrubs, they contain a high percentage of oil in their flowers and fruits, and they are widespread in the tropical and semi-tropical climate zone. Olea europae L. sativa is the most economically suitable for olive and olive oil cultivation. The cultivated species in this family contain more oil than the others.
Apart from the coastal areas, it also lives in the interior areas with suitable climatic conditions for the cultivation of olives due to the low elevations. The most productive environment for the olive tree, which is suitable for growing in arid lands, is the climate with hot summers and mild winters. Provided that frost and water needs are met, it is drought-resistant, living at temperatures between -7 and +40 C°, and can survive up to an altitude of almost 800 meters. Today, there are olive groves at 1200 meters in Spain, 1700 meters in the Atlas Mountains in Morocco and 2000 meters in Argentina. It is a tree that loves southern slopes, is content with soil up to 2 meters deep, and is not very selective in terms of soil properties where it can survive.
It can be grown without irrigation in areas where the annual precipitation reaches a minimum of 600 mm. An average of 220 mm of precipitation per year is sufficient for the efficient growth of the olive tree. Olives can be grown in the desert soil by drip irrigation for 14 hours a day and 10 months a year on the banks of the Nile in Egypt. Slightly chalky, sandy, gravelly and clayey soil is sufficient for its growth, it is called "rich tree of poor soils".
Approximately 75% of the olive groves in our country are located on sloping, mountainous and sloping lands. The fact that the olive, which is generally a long-lived tree of 300-400 years, lives for 2000 years is probably because it is a plant that is not affected by drought.
Morphological Characteristics of the Olive Tree
The trunk of the tree consists of two parts. Just under the ground, there is another trunk that is wider than the trunk, forming tubers, and its roots spread out from there. This part of the tree trunk that is under the ground is called a “radish”, and the swelling around it is called a “tuber”. Radishes are the tree's reserve food store. It stores excess moisture and plant nutrients here. Any part of the olive tree has the ability to form roots. But especially tubers make more roots. When the tree is deprived of fertilizer and water, it survives on this reserve food. This is why olive trees do not dry out easily like other fruit trees when they are without food and water. Most of the radish is under the ground and its base is flat. Among the people, radish is also called "çotuk". The normal stem rises above the ground or just after the tubers, taking a thinner form. The stem has an indented, crooked appearance due to the different growth. As the tree ages, cracks begin to form in its smooth gray bark. The crown (top) of the tree expands every year, while the crown shows an open and asymmetrical development in fertile soils, it is dense and rounded in infertile soils. Its body is very resistant to decay. Moreover, when it completes its life, a new tree can sprout from its roots. That's why the name "Immortal tree" is ascribed to it.
The inner veining of the trunk is aesthetically decorative. It was used in sculpture in ancient times, today it is used in the manufacture of furniture and objects, heat production is high when used for firewood purposes.
Its roots usually extend up to 1.5 meters, if necessary, it can reach 3 times the depth of the trunk. The place where olive roots are most intense is between 25-60 cm. The seedling forms a pile root in its first years, the roots extending to the side over the years begin to form capillary branches close to the surface of the soil after a while. With these capillary branches, it can reach up to three meters from the bottom of the trunk. It has been shown that the trees in the olive groves communicate with each other through their lateral roots.
Although the olive leaf varies according to the type, it is 6 cm long and 1 cm wide on average. Its lower surface is bluish silvery-gray in color, the surface is covered with silky hairs, rich in stomata, it plays an important role in adaptation to arid climate conditions and gas exchange functions by reducing water loss. The upward-facing face is hairless, rich in chloroplasts that carry out photosynthesis by absorbing sunlight. Olive loves light, its yield increases in sunny areas. The leaves have an average life of 2-2.5 years, renewal takes place in spring. Olive leaves contain tannins (polyphenol molecules with a bitter taste), essential oils, organic acids, and squalene.
It starts to produce products approximately 5 to 8 years after it is planted as a sapling. When it reaches the age of 15, it reaches the age of full yield, its yield continues to increase until the age of 35, then it starts to decrease. Its average lifespan is 300 years, theoretically it can live 2000 years, “from the father of figs, from the ancestor of olives”.
Olive Tree Flower
There are two types of flowers, one is hermaphrodite and turns into fruit, and the other is a sterile flower. Small whitish/yellow colored, odorless flowers are fertilized by the wind – and some insects – and evolve into fruit. In order for flowers to appear on the branches, the tree needs exposure to cold. In this phase – January as a period – the tree should encounter a cold below +7 degrees for an average of 50 hours. Flowering begins in April to May. Flowers with both male and female reproductive organs have 2n=46 chromosomes. A complete olive flower contains two male and one female organs. The period when the tree is most sensitive to weather conditions is the process of transforming the flower into fruit. Olives begin to form in May-June, about 2 weeks after flowering. In a year with a lot of flowering, it is enough for 2% of the flowers to turn into olives to have a high yield.
Fruit productivity is not the same every year, while the olive tree yields in one year, it prepares itself to rest and yield in the next year, yields less fruit as fruit, this feature is called "periodicality". It is also called the 'year of absence' and 'year of absence' among locals. Although the periodicity feature of the tree has a unique character; This character is also associated with multiple external factors such as climate, lack of regular pruning, unconscious fertilization, wrong harvesting practices and faulty tillage. Controlling these factors can result in less product reduction due to periodicity.
Olive as a Fruit
Although it differs according to the species, it mostly has an oval appearance, it forms an average of one fifth of the nuclei, but depending on the species, the nucleus may be smaller or larger. The majority of the composition of the mesocarp, called the fruit pulp, is water, about one-fifth of which is fat, and the remainder is composed of protein, fiber, ash and sugar. It also contains minerals, carotene, vitamin C, vitamin B1.
The size of the olive, which is the fruit of the tree, varies according to the type of tree, its dimensions can range from 1.5 grams to 17 grams, it has an elliptical structure with an average length of 2 cm and a width of 1 cm. It is classified in the group of stone fruits. In our country, the biggest olive is the İzmir Tableware variety with a weight of 7.5 g, and the smallest one is the Kilis Oil variety with a weight of 1.7 grams.
The fruit, which has a green color when it first appears, takes on different colors depending on the type over the months as it matures, and turns into a red/black, bright black, burgundy, purple or light green color. There is no oil in the peel, the oil is obtained from the flesh and seed of the fruit. There are nearly 30 varieties in the literature in our country. However, it is thought that Anatolia is very rich in terms of olive varieties and that there may be many species that have not been mentioned in the literature.
During fruit development, biochemical, physical and physiological changes occur in the fruit structure and have a direct effect on the table and oil quality of olives.
It is known that the total of olive groves in different geographies of the world is 8 million hectares on average. Our country has more than 10% of this asset and is one of the major olive producers in the world.
Olive is a good food and energy source for birds with its rich oil content. It is consumed as a food source by thrushes, black chickens, starlings and many songbirds. Birds can consume olives on a branch or olives below a certain size that have fallen to the ground. After digesting the flesh of the fruit, they discard the core with their feces. The olive seed is hard and woody, so it is difficult to form seedlings from the seed. It has been understood that some of the mentioned bird species soften and refine the hard surface structure of the bean through the enzymes in their digestive systems. Studies have shown that the olive tree spreads in nature through these olive kernels, which are softened and dropped to the ground with bird droppings.
Olive Farming
Although the wild olive tree lily (Olea europaea L. oleaster) is a durable tree in its natural environment, it requires correct agricultural practices when it is desired to reproduce the improved type (Olea europae L. sativa) by cultivation. Plowing the soil deeper than 10 cm may damage the capillary roots, fertilizer and nutrient applications and doses should be determined according to the results of soil analysis. Regular irrigation in summer, provided that it is not excessive, increases the yield and grain size. Pruning rejuvenates the tree. Cutting the excess of new branches, called shoots, helps the tree to spend the energy it would spend to feed these branches for fruit formation and growth. Care should be taken not to damage the branches during harvest. If possible, olives should be collected by hand, and in cases where it is not possible, modern mechanized methods should be applied to whip the branches.
Compiled by: Uğur Saraçoğlu (ugisaracoglu@yahoo.com.tr)
Resources:
1. World Olive Encyclopedia; International Olive Council; Fausso Luchetti, 1997.
2. Olive oil; Fahrettin Göğüş, Mücahit Taha Özkaya, Semih Ötleş, Eflatun Publishing House, 2009.
3. Physiology of the Olive Tree; Lecture Notes: 9, Dr. Mücahit Kivrak, Balikesir University Edremit Vocational School, Olive Growing Department.