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• Background and Aims Olive cultivars and their wild relatives (oleasters) represent two botanical varieties of Olea europaea subsp. europaea (respectively europaea and sylvestris). Olive cultivars have undergone human selection and their area of diffusion overlaps that of oleasters. Populations of genuine wild olives seem restricted to isolated areas of Mediterranean forests, while most other wild-looking forms of olive may include feral forms that escaped cultivation.• Methods The genetic structure of wild and cultivated olive tree populations was evaluated by amplified fragment length polymorphism (AFLP) markers at a microscale level in one continental and two insular Italian regions.• Key Results The observed patterns of genetic variation were able to distinguish wild from cultivated populations and continental from insular regions. Island oleasters were highly similar to each other and were clearly distinguishable from those of continental regions. Ancient cultivated material from one island clustered with the wild plants, while the old plants from the continental region clustered with the cultivated group.• Conclusions On the basis of these results, we can assume that olive trees have undergone a different selection/domestication process in the insular and mainland regions. The degree of differentiation between oleasters and cultivated trees on the islands suggests that all cultivars have been introduced into these regions from the outside, while the Umbrian cultivars have originated either by selection from local oleasters or by direct introduction from other regions. [ABSTRACT FROM AUTHOR]

A collection of 52 local Iranian olive genotypes (North and south of Iran) and 36 olive cultivars from Mediterranean countries were studied in order to determine the genetic structure and their relationships. Thirteen primer pairs of microsatellite loci were selected that were known to be discriminating from previous study on olive. Polymorphic Information Content values ranged from 0.51 to 0.95. The Gst analysis for SSR loci revealed that some of the loci are more common while, some other loci are present in certain populations and show limited distribution among populations. Analysis of molecular variance (AMOVA) revealed that 11.71% of genetic variation attributed to differences between geographical regions while 88.29% came from variation in within regions ( P < 0.05). Pairwise Fst test revealed significant differences ( P < 0.05) between populations except between West and East Mediterranean populations. Neighbor Joining cluster analysis grouped the olive cultivars in two distinct clusters separating, olive genotypes located in North of Iran from the rest of olive cultivars studied. STRUCTURE and K means analyses showed the presence of distinct groups in olive trees and revealed variability in allelic compositions and their frequency between Iranian and West and East Mediterranean olive cultivars. The results of Bayesian clearly revealed that due to frequent occurrence of gene flow, the West and East Mediterranean olive cultivars had lower Fst values compared to the other population groups. In present study, genetic structure revealed admixture allelic compositions among Mediterranean olive cultivars different from Iran genotypes. [ABSTRACT FROM AUTHOR]

Olive trees have been traditionally cultivated in dry conditions as it is a crop very well adapted to Mediterranean dry lands. Foliar fertilization is a widespread application method used by olive growers to correct frequent deficient levels of potassium in olive trees under rainfed conditions. Monopotassium Phosphate (MKP) is an economic and easily available fertilizer and a fast source of P and K when it is applied as a foliar spray. The influence of environmental and formulation factors on the efficiency of MKP foliar application has never been evaluated. In this study the different responses of five MKP foliar treatments (control-untreated, MKP3% at dayligh, MKP3% overnight, MKP3% plus urea and MKP3% plus surfactant) on olive trees under field conditions were evaluated during three different application times (April, July, and November). In all cases, MKP3% plus urea and MKP3% plus surfactant increased P contents with July being the most effective treatment month. All treatments, except MKP3% at dayligh, improved the K nutritional state of olive in July, but not in November or April. In general, the addition of urea and surfactant to the MKP3% solution and its application in July improved its efficiency on olive trees, most likely due to the higher proportion of young leaves present during this period. [ABSTRACT FROM AUTHOR]

Olive is a long-living perennial species with a wide geographical distribution, showing a large genetic and phenotypic variation in its growing area. There is an urgent need to uncover how olive phenotypic traits and plasticity can change regardless of the genetic background. A two-year study was conducted, based on the analysis of fruit and oil traits of 113 cultivars from five germplasm collections established in Mediterranean Basin countries and Argentina. Fruit and oil traits plasticity, broad-sense heritability and genotype by environment interaction were estimated. From variance and heritability analyses, it was shown that fruit fresh weight was mainly under genetic control, whereas oleic/(palmitic + linoleic) acids ratio was regulated by the environment and genotype by environment interaction had the major effect on oil content. Among the studied cultivars, different level of stability was observed, which allowed ranking the cultivars based on their plasticity for oil traits. High thermal amplitude, the difference of low and high year values of temperature, negatively affected the oil content and the oleic acid percentage. Information derived from this work will help to direct the selection of cultivars with the highest global fitness averaged over the environments rather than the highest fitness in each environment separately.

Background and Aims: This study examines the pattern of genetic variability and genetic relationships of wild olive (Olea europaea subsp. europaea var. sylvestris) populations in the north-western Mediterranean. Recent bottleneck events are also assessed and an investigation is made of the underlying population structure of the wild olive populations., Methods: The genetic variation within and between 11 wild olive populations (171 individuals) was analysed with eight microsatellite markers. Conventional and Bayesian-based analyses were applied to infer genetic structure and define the number of gene pools in wild olive populations., Key Results: Bayesian model-based clustering identified four gene pools, which was in overall concordance with the Factorial Correspondence Analysis and Fitch-Margoliash tree. Two gene pools were predominantly found in southern Spain and Italian islands, respectively, in samples gathered from undisturbed forests of the typical Mediterranean climate. The other two gene pools were mostly detected in the north-eastern regions of Spain and in continental Italy and belong to the transition region between the temperate and Mediterranean climate zones., Conclusions: On the basis of these results, it can be assumed that the population structure of wild olives from the north-western Mediterranean partially reflects the evolutionary history of these populations, although hybridization between true oleasters and cultivated varieties in areas of close contact between the two forms must be assumed as well. The study indicates a degree of admixture in all the populations, and suggests some caution regarding genetic differentiation at the population level, making it difficult to identify clear-cut genetic boundaries between candidate areas containing either genuinely wild or feral germplasm.