In this context, the implementation of climate change adaptation strategies is essential to ensure the long-term sustainability of olive-growing systems. Thus, the controlled deficit … the implementation of climate change adaptation strategies is essential to ensure the long-term sustainability of olive-growing systems. irrigation in vast areas of southern Spain, which, with water allocations well below optimal levels, yields excellent results compared to rain-fed olive groves. Olive varieties The olive tree has traditionally been characterised by its vast genetic heritage, with countless varieties having been described in all the main producing countries. In Spain alone, the latest survey and cataloguing work indicates the existence of 427 cultivated varieties (Gómez-Gálvez et al., 2024). These varieties were selected by farmers of irrigation strategies already represent a substantial advance in the profitability of these systems, constituting a key element in ensuring their sustainability. Controlled deficit irrigation strategies are based on the olive tree’s varying sensitivity to stress, depending on its current phenological stage. Thus, the phenological stages of flowering, fruit set, ripening and lipogenesis are highly sensitive to water and heat stress, which must therefore be avoided. The aim of these strategies is to minimise water stress during these stages as much as possible, which is sometimes difficult in terms of availability water and in the The olive tree has traditionally been characterised by its vast genetic heritage, with countless varieties having been described in all the main producing countries. old over the centuries, meaning that most of them can be considered to be over a hundred years old, with some even dating back millennia. Some have also spread, under different names, throughout the Mediterranean basin. case of limited irrigation allocations. Controlled deficit irrigation schedules usually concentrate the available water during the spring until the stone hardens, to ensure the harvest, and, above all, at the end of summer, when the water available in the soil is practically nil, as it has been consumed throughout the growing season, and lipogenesis processes are of great importance. Thus, if water availability is scarce, summer is the time when the plant can withstand a certain degree of stress, affecting fruit growth, provided the fruit is intended for olive oil production. The same does not apply when the olive grove is intended for the production of table olives, which require water to maintain the size and turgidity of the fruit, so as not to compromise quality. This strategy of reducing irrigation in summer for olive groves intended for olive oil production – which is in line with the olive tree’s physiological processes that restrict stomatal opening when environmental conditions are very severe – forms the basis of the application This enormous varietal diversity was preserved until, more recently, changes in olive cultivation introduced alterations to the traditional varietal structure. Initially, the modernisation of olive groves led to the expansion of a small number of varieties, considered agronomically more suitable for an intensive system, which gradually replaced many of the other traditionally cultivated varieties. Thus, for example, in Andalusia, the world’s leading producing region, just four varieties (Picual, Hojiblanca, Arbequina and Manzanilla de Sevilla) account for over 90 per cent of the olive grove area (CAPADR, 2025). The development and subsequent expansion of hedgerow cultivation have made the need for new varieties adapted to this new system even more evident. The high planting densities and the fact that the trees are confined within relatively small hedgerows mean that most traditional varieties do not adapt well to the system, as they are excessively vigorous, large in size and have very 42 CULTIVAR ANALYSIS AND PROSPECTIVE STUDIES No. 35 Olive groves and olive oil
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