The olive grove of the future: how to select the best materials for productivity… 91 Depending on the vegetative growth of the olive trees, varieties can be recommended according to the type of olive grove: • Traditional or intensive rain-fed olive groves with vase training: varieties with strong vigour and an upright or open growth habit (either on their own roots or using vigorous rootstocks, as well as varieties of medium to low vigour). In traditional or intensive olive groves with irrigation: varieties of medium to low vigour are used. • Hedgerow olive groves: varieties with medium to low vigour, a medium growth habit and extensive lateral branching. The model olive tree for hedgerow olive groves A genetic improvement programme based on hybridisation requires the conception of an ideal plant model to be achieved. This involves conceiving the ideal plant in terms of various aspects: morphological, physiological, productive and environmental adaptability; capable of yielding a product in sufficient quantity and of a quality appropriate to its intended use – olive oil or table olives; and resistant to or tolerant of pests and diseases, as well as the most common abiotic stresses. Figure 2 – Hedgerow olive grove The hedgerow olive grove system (Figure 2), which is highly mechanised, requires a very specific varietal ideal type. The model olive tree for this system aims to maximise production efficiency, facilitate mechanical harvesting and ensure resistance to stress factors. Based on the characteristics of the species, ideally, these olive trees should include: • Architecture and growth: trees of low to medium vigour; compact, upright habit and short branches, but with a high level of branching on the fruiting branches. • Production behaviour: trees entering production early or very early; high productivity per unit area; and consistent production. • Fruit characteristics: high olive oil yield; and fruit with a good pulp-to-stone ratio. • Tolerance/resistance to the most common pests and diseases, such as the olive fruit fly, olive moth, peacock spot and olive scale. The integration of these characteristics will help reduce dependence on plant protection products and increase the sustainability of production systems. Training systems such as the hedgerow olive grove were developed on the basis of foreign varieties. Portuguese native varieties are traditionally associated with olive groves trained in the vase system (traditional or intensive). However, some native varieties possess agronomic characteristics compatible with the hedgerow olive grove system and which can contribute to the creation of more resilient and productive olive groves under Mediterranean conditions. Genetic improvement of the olive tree through hybridisation The olive tree is a species well-adapted to regions with a Mediterranean climate, where winters are mild and rainy and summers are hot and dry. In this region, as a result of climate change, there will be a rise in temperatures, a concentration of rainfall, and a greater number of extreme events (temperature and rainfall) of longer duration.
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