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The characterization of tree canopy traits represents a key step to identify potential cultivars adaptable to a specific growing system. Developing methodologies to rapidly evaluate canopy traits allows to classify cultivars in germplasm banks and facilitates selections in breeding programs. In the present work, the ability of low-cost unmanned aerial vehicle (UAV) was compared with on-ground traditional methodology for measuring canopy traits (namely crown diameters, tree height and crown volume) in trees of the Worldwide Olive Germplasm Bank of Córdoba. The evaluated trees belonged to a wide range of cultivars and were planted in three different dates. A wide variability was found for the four parameters measured with both on ground and UAV methodologies. Besides, a significant linear correlation was observed at tree and cultivar level, with relative errors that ranged from 4.44 to 13.9 % for axial parameters or from 17.0–29.0% for volume, depending on the planting date considered. ANOVA and Tukey's results showed a high agreement between both methodologies in identifying cultivars with similar vigour values. When comparing means over time, the UAV-based data allowed a slightly better detection of significant differences than on-ground data. The results provided by the present research indicated that the use of UAV is a reliable methodology to study tree canopy traits in olive germplasm banks, supporting breeders to the identification and definition of the genetics behind crop variability. The evaluation here performed indicates that there is a wide variability on canopy traits on the cultivated olive germplasm that could be exploited to select potential cultivars for different growing systems.

The control of the olive tree vigor is a critical factor to ensure adequate production and longevity of high-density olive cultivation. To deal with this problem, we intend to take advantage of the genetic variability present in the wild subspecies of Olea europaea to identify genotypes of reduced vigor with optimal adaptability to diverse soils and adverse environmental conditions. In this work, early vigor traits have been characterized in different wild olive subspecies that could potentially be used as rootstocks to control the vigor of grafted cultivars. Significant differences between genotypes were obtained for all vigor traits and high values of broad sense heritability were obtained for most of them, indicating strong genetic effect and therefore good possibilities for selection. Compared to ‘Arbequina’ and ‘Picual’ cultivars, some of the wild genotypes evaluated showed a clearly lower vigor at the end of the experimental period. These genotypes could be tested as dwarfing rootstocks for high-density olive plantations.

Inventorying, characterising and conserving on-farm ancient olive trees is a priority for safeguarding their genetic, natural and agricultural value and for protecting ancient genotypes threatened with extinction. In the “Taula del Sénia” (M-TdS) area (northeast Iberian Peninsula) a highly important cultural landscape has been preserved, in which the olive groves play an outstanding social and economic role: the ancient olive trees, sustained by many local farmers, constitute a living heritage and provide a clear example of High Nature Value (HNV). A total of 4526 ancient productive olive trees, with a trunk circumference (PBH) larger than 3.5 m, were inventoried and their spatial localization and biometric measurements were collected. 41 olive trees have shown the highest category in monumentality (PBH >8.1 m). The outstanding trees might be 634–1082 years old. The endocarp morphology of a representative sample of the most ancient trees from this settlement resulted in 14 different profiles. The ancient trees genotyped, through eight simple sequence repeat (SSR) markers, revealed 43 SSR profiles. The use of SSR enabled us to verify that most of the trees (98%) belong to the local cv. ‘Farga’, a male sterile variety with a rare chlorotype, only a few trees corresponded with other local varieties, ‘Morrut’, ‘Canetera’ and ‘Sevillenca’, and ten hitherto unidentified genotypes were distinguished, some with chloroplast lineages different from the ‘Farga’ type. The M-TdS area holds a unique living and exploitable heritage with the highest concentration of ancient olive trees worldwide. On-farm conservation of this germplasm by the community of local growers is enabling preservation of this important source of genetic variation, potentially holding traits of resilience and adaptation to adverse soil and climatic conditions, demonstrated by the survival of these trees over the centuries. Farmers have undertaken initiatives to valorize the olive oil deriving from these M-Td

Ethanol is a substrate for the chemical synthesis of fatty acid ethyl esters (FAEE) during storage of virgin olive oil whose contents are officially regulated. Given the impact that the ethanol content might have on the olive oil commercialization, the level of this metabolite has been studied in an array of olive genotypes representing the diversity available in olive (Olea europaea L.). Substantial levels of ethanol have been found in the oils of all genotypes under study. Moreover, increasing levels of alcohol dehydrogenase activity have been found during olive fruit ripening in good correspondence with the accumulation of ethanol in advanced stages of fruit maturation. The results suggest that ethanol has a ubiquitous character in the fruits of Olea europaea and, therefore, in all the oils obtained from them. Besides, their concentration seems to depend on the cultivar, ripening stage and climatology, not discarding the influence of the growing conditions. Data suggest that the application of olive oil regulation for FAEE levels should consider the presence of basal levels of ethanol in the oils, which are quite high in many cultivars.

Phenolics are claimed to be one of the main responsible for the health benefits associated to the long term consumption of virgin olive oil (VOO). The variability of the phenolic composition was studied in an olive cultivar core collection which holds an extensive genetic diversity. The most abundant VOO phenolics were the secoiridoid derivatives resulting from the hydrolysis of oleuropein, ligstroside and demethyloleuropein present in the fruit, which showed to be on average their main phenolic glucosides. Total phenolic compounds in the fruits and the oils were, in general, significantly and positively strong correlated (r = 0.82) with p < 0.001. Thus, the fruit phenolic content seems to be the main factor determining the synthesis of VOO phenolics during oil extraction. Data on phenolic composition would be of interest for the selection of optimal parents in olive breeding programs with the aim of obtaining new cultivars with improved functional quality.

DArT (Diversity Array Technology) markers assessed in a large set of olive cultivars have been used to evaluate their utility for the management of the World Olive Germplasm Bank (WOGB-Córdoba) of IFAPA Centre >Alameda del Obispo> Córdoba (Spain). The coefficient of similarity of Kulczynsky (K1), which calculates the ratio between common markers relative to the number of unique markers (range 0 to ∞), was used for such purpose. Low K1 values (lower than 3.61) were obtained for the majority of the pair of cultivars (99.80% of the total). Low and similar ranges of K1 values were also found in both a seedling progeny of 'Picual'. ×. 'Arbequina' and a set of wild olives included in the study. These results may suggest that most of the WOGB-Córdoba cultivars studied probably were derived from outcrossing events. As expected, low similarity values were found among different cultivars with the same naming (homonyms). On the contrary, a total of 105 pairs (0.20%) showed K1 values above 14.58, implying thus low genetic differentiation. These high K1 values suggest the presence of potential redundant germplasm in the collection which likely includes synonyms, accumulation of somatic mutations, redundancies from prospecting surveys, and planting errors. Thus, the genetic relationships revealed by DArT markers among cultivars are of great interest for management of olive collections and could be useful to increase the performance of future breeding programs by optimizing the choice of parents in combination with phenotypic information. Finally, the transferability of DArT markers to wild olives has been confirmed. © 2013 Elsevier Ltd.

The genetic diversity of wild olive trees sampled from eight different sites from two provinces of Andalusia (Cadiz and Jaen), Southern Spain, was evaluated by means of agro-morphological traits and SSR markers. The agro-morphological traits showed a high variation between genotypes and significant correlation coefficients were obtained among the values recorded in two consecutive years, 2007/08 and 2008/09 (r= 0.59-0.78). Traits such as fruit symmetry (position A), stone shape, fruit flesh/stone ratio and olive oil content on both wet and dry matter, showed the highest values of diversity and were very useful in genotype discrimination. As expected, average values obtained in wild olives for fruit size and oil content were lower than the previously reported in cultivated material. However, it is noticeable that wild trees with fruit weights (1.3. g) and olive oil percentage in dry matter (33.8%) comparable to the values found in some olive cultivars, were also found. With both DNA-based and agro-morphological descriptors, higher levels of variability were found within each site than between sites. Genetic variation observed among the wild olive germplasm at the DNA level was higher than the agro-morphological traits, indicating the efficiency of SSR markers for detecting genetic diversity among wild olive genotypes and their relationships. The lack of consistency between the relationship studies performed with molecular and morphological markers could indicate that each marker system measures different aspects of the wild olive genetic variability. Molecular data obtained by SSR markers together with morphological and agronomical characterization of olive trees confirmed the high diversity within the wild populations and their potential use for olive breeding. © 2011 Elsevier B.V.