Arbequina IRTA-i18: the clone behind super-high-density olive groves

Arbequina IRTA-i18 is not Arbequina itself but a registered type developed from it by clonal selection. The distinction matters when planting: saying "I planted Arbequina" is not the same as "I planted IRTA-i18", because spacing, time to bearing and harvest method are planned differently.

What clonal selection means

Within a variety, small differences exist from tree to tree. Clonal selection means choosing one tree that carries the wanted traits and propagating it by cuttings. The resulting grove is genetically uniform: trees flower together and ripen together. That uniformity is essential for mechanical harvesting, because a harvester does not judge ripeness tree by tree.

IRTA-i18 was developed this way in Spain and selected for super-high-density (hedgerow) systems. The IRTA in its name is the abbreviation of the Catalan research institute that made the selection.

What super-high-density changes

In a traditional grove trees are planted at 6×8 or 7×7 metres, giving 17-27 trees per decare. In a super-high-density system rows are narrowed, the trees form a hedge, and tree count per decare rises many times over. Our measurements record 27.7 trees per decare for Arbequina; super-high-density systems go well beyond that.

The system has three consequences. First, early bearing: because the tree is kept small, investment in root and trunk falls and fruit arrives sooner. Second, mechanical harvest: a machine passing along the row cuts labour cost sharply against hand picking. Third, a shorter life: in a dense system the trees do not last centuries as in a traditional grove but carry a far shorter economic life. The grove is planned as a production facility rather than an inheritance.

Cold tolerance and chilling

Our records give Arbequina's chilling requirement as 289 chilling units (459 hours). That is among the lowest in our comparison: Adana Topağı 346 hours, Karamürsel Su 526, Domat 552, Gemlik about 600, Memecik 624, Çakır 1,000.

A low chilling requirement means the variety can still form flower buds where winters are mild — favourable for southern regions. It should not be confused with frost hardiness; the two are different. Chilling describes how many cool hours winter must provide; frost hardiness describes the temperature at which the tree is damaged.

Self-fertility and pollinators

Arbequina types are considered self-fertile, meaning they can set fruit alone. Even so, a foreign pollinator raises fruit set in self-fertile varieties. In super-high-density groves, Arbosana and Koroneiki are the usual pollinators. The pollinator plan belongs in the planting plan at the sapling selection stage.

Oil content and quality

Arbequina oil gives a fruity, sweet profile with low bitterness; it suits those looking for a mild oil rather than a pungent one. Combined with the early harvest typical of dense systems, it yields an oil with strong sensory attributes but a short life.

For comparison: in our records, the highest oil contents belong to Kalem bezi and Kilis yağlık at 31 percent, with Gemlik at 29-30. Arbequina does not sit at the top of that list; the system's advantage comes not from oil content in the fruit but from total yield per decare and low labour.

What to check before planting in Türkiye

Super-high-density is a capital-intensive choice: sapling numbers are high, a post-and-wire system is needed, irrigation is close to mandatory, and access to a harvester is essential. Without the machine the system's main advantage disappears; hand picking a densely planted grove is harder than a traditional one.

The second question is soil and water. A dense system does not withstand drought as a traditional grove does, because root volume is small. The third is market: the sales channel must be decided, because this system pays by lowering unit cost, not by commanding a premium price.

You can compare measured data for varieties grown in Türkiye on our variety pages.