Cultivar suitability for different olive growing systems

Traditional olive orchards are planted at wide distances among trees (8-9 m) and are trained to form canopies with large volumes. In those orchards, vigorous cultivars are suitable to rapidly establish sufficient tree size to have commercial yields. Most of the olive cultivars existing today were selected by the growers to fit in this growing system.

However, a significant trend to intensification has been evidenced in the olive orchards planted in the last decades. This intensification consisted of an increase in plant density and a trend towards mechanising the different tasks, especially, harvesting. This new trend needs trees that can be trained to form low volume canopies that can also bear fruits on a regular basis. Therefore, medium-and low-canopy volume cultivars (Table 1) will be better adapted to the new olive orchards, especially those planted in a hedgerow system. Besides, the lower the canopy, the less costly are the pruning operations, which is one of the most labour-consuming tasks in olive growing. Obviously, other characteristics, such as branching habits, branching flexibility, productivity, oil content and composition, among others, should also be considered to select the best cultivar for any given environmental and management conditions.

Due to the high interest in hedgerow growing systems over the last decades, several breeding programs have obtained new cultivars with particularly low vigour and growth habits to fit into this system. These included Sikitita, Sikitita2, Martina, Lecciana, Oliana, Coriana, I15 and Sultana. Added to this are to Arbequina and Arbosana, the two traditional cultivars most widely planted in the hedgerow system. It is quite likely that more cultivars adapted to this system will be produced in the future. However, all of them need to be tested in different climatic conditions  and over enough years to accurately determine their vigour in long-term cultivation and, therefore, their suitability for training in high-density growing systems.

Table 1. Categorisation of the canopy volume of trees of olive cultivars, measured 4 years after planting and before any pruning was applied.