92 CULTIVAR ANALYSIS AND PROSPECTIVE STUDIES No. 35 Olive groves and olive oil Plant breeding is, by definition, a key tool for developing varieties that are not only more productive but also more resilient to abiotic and biotic stresses. The first stage of breeding is the creation of inter-varietal genetic diversity. Given that the olive tree is a heterozygous and allopolyploid species, the variability is expected to be very extensive. Initially, we worked with openpollinated progenies of ‘Galega Vulgar’ and ‘Cobrançosa’, and in recent years we have launched a programme of controlled pollination involving targeted crosses between olive varieties, selected on the basis of growth habits, early maturity, productivity, consistency, profitability and resistance to the main diseases and pests. Each olive tree grown from seed exhibits unique and distinctive characteristics (Figure 3). The process involved in developing a new olive variety is a long one, and the genotypes are evaluated from the very first years. At the end of each stage, a selection process takes place, whereby the most promising genotypes – those meeting the selection criteria defined by the programme – are chosen, and these proceed to the next stage. Figure 3 – Olea europaea L. seedlings, 6 months after germination Prior to the first selection stage, the materials, following germination, undergo a period of forced vegetative growth with the aim of shortening the juvenile phase (Figure 4) (under natural conditions, this can last between 10 and 15 years). The juvenile phase ends when inflorescences are first observed. Figure 4 – Olea europaea L. seedlings in the growth-forcing phase The first stage involves the evaluation and selection of the best of these genotypes (F1). The main selection criteria are early entry into production and oil yield. Upon completion of this stage, the best F1s are propagated vegetatively, with a view to establishing experimental plots with replicates at various locations. Among the progeny of ‘Galega Vulgar’, the overall objective is to select genotypes with high levels of resistance to olive knot and higher oil yields, whilst preserving vigour, early maturity and olive oil quality. Currently, two genotypes under consideration as candidates for new olive varieties are at an advanced stage of selection. The contribution of new technologies to our understanding of olive plant material The introduction of monitoring technologies has been transforming the way in which the agronomic behaviour of varieties is understood, monitored and evaluated. The integration of sensors applied to the soil, the plant and the fruit enables a more objective, continuous and real-time approach. This equipment is an essential tool for the objective assessment of varietal performance, enabling the identification of genotypes that are more waterefficient and more resilient to stressful conditions. Furthermore, emerging technologies, including optical sensors and artificial intelligence-based approaches, have demonstrated potential in the classification of varieties and the assessment of
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