Olea europaea

Pistil abortion is considered to be an evolutionary adaptation to save resources in andromonoecious species, balancing the number of pistils with the resources available. It follows that large-fruited species/cultivars should have greater levels of pistil abortion. Working in olive, we found that pistil abortion, expressed as percentage of staminate flowers, was positively correlated to the average ovary mass at bloom,

The vesicular-arbuscular mycorrhizas (AM) are very significant in the life of most plants including olive tree (Olea europaea L.), which is of great economic importance. However, due to its wide distribution, especially, in the Mediterranean, it is subject to various environmental stresses, particularly drought and aridity. This study aims to evaluate the percentage of root colonization of olive by arbuscular fungi along a climatic gradient (sub-humid, semi-arid and arid), and to estimate how this varies depending years (2010-2012) and seasons (fall, winter, spring and summer). Results showed that the roots of the olive tree are colonized by arbuscular endomycorrhizal fungi under the three types of climate, whatever the season or the study years. Mycorrhization parameters revealed a frequency of colonization (F%) of up to 83%, mycorrhizal intensity (M%) reaching 42% and a rate of arbusculars in the mycorrhizal parts of root fragments (a%) of 4%. Mycorrhizal colonization varies between bioclimatic zones. It is more frequent and intense in the sub-humid climate. Mycorrhiza also varies according to the season; it is more important in spring and slight in winter. This study allowed the characterization, for the first time, of the mycorrhizal status of olive in the northeastern Algeria, and estimate variations of that colonization depending on seasons and climate types.

This paper examines the forest communities dominated by Olea europaea L. var. sylvestris (Mill.) Lehr. that have been described up until now in the Mediterranean Region (including other isolated extrazonal areas in the northwestern Iberian Peninsula and in Northern Turkey) as more or less evolved aspects of woods, microwoods and high maquis that principally tend to make up climacic and edapho-climacic “series heads”. These formations maintain a significant large-scale distributive potential within the infra- and thermomediterranean bioclimate belts (with a few penetrations into the mesomediterranean) with a dry-subhumid (and sometimes humid) ombrotype; however, they are currently quite rare and fragmented in the wake of large-scale deforestation and the impoverishment of old-growth communities dominated by a species known to live for millennia. The study was conducted through the analysis of phytosociological data taken from the scientific literature and other unpublished data regarding North-Africa (Morocco, Algeria), the Iberian Peninsula, the Balearic Islands as well as other islands from the Tyrrhenian area (Sardinia, Corsica, Sicily and its minor islands), the Italian Peninsula, the Balkan Peninsula, the Aegean region, Turkey and the southern Anatolian coast. A comparison between the different communities has shown a high floristic and physiognomic-structural homogeneity that justifies their categorization in the Quercetea ilicis class. The biogeographic and ecologic vicariance shown by the same formations within the large Mediterranean distribution range makes it possible to subdivide them into the following orders and alliances: 1) Pistacio-Rhamnetalia alaterni [A) all. Tetraclini articulatae-Pistacion atlanticae (suball. Pistacienion atlanticae); B) all. Asparago albi-Rhamnion oleoidis; C) all. Oleo sylvestris-Ceratonion siliquae]; 2) Quercetalia calliprini [D) all. Ceratonio-Pistacion lentisci]; 3) Quercetalia ilicis [E) all. Querco rotundifoliae-Oleion sylvestris; F) all. Fraxino orni-Quercion ilicis; G) all. Erico arboreae-Quercion ilicis; H) all. Arbuto unedonis-Laurion nobilis (suball. Arbuto-Laurenion nobilis)]. Regarding the syntaxonomical aspect: (i) two new associations are described [Hippocrepido emeroidis-Oleetum sylvestris and Junipero foetidissimae-Oleetum sylvestris]; (ii) two new associations [Phillyreo latifoliae-Oleetum sylvestris Barbero, Quézel & Rivas-Martínez ex Gianguzzi & Bazan ass. nova and Calicotomo intermediae-Oleetum sylvestris Quézel, Barbero, Benabid, Loisel & Rivas-Martínez 1988 ex Gianguzzi & Bazan ass. nova] and a new subassociation [Aro neglecti-Oleetum sylvestris Rivas-Martínez & Cantò 2002 corr. Rivas-Martínez & Cantò fraxinetosum angustifoliae Pérez Latorre, Galán de Mera, Deil & Cabezudo ex Gianguzzi & Bazan subass. nova] are leptotypified; (iii) a nomen novum of the association is redefined [Rhamno laderoi-Oleastretum sylvestris (Cantò, Ladero, Perez-Chiscano & Rivas-Martínez 2011) Gianguzzi & Bazan nom. nov.].

We report results of palynological investigation of a core of sediments extracted from the bottom of the Sea of Galilee. The core was sampled at high resolution for both palynological analysis (a sample was taken c. every 40 years) and radiocarbon dating. The article focuses on the Early Bronze and Intermediate Bronze Ages, c. 3600–1950 BC. The results enable reconstruction of the vegetation and thus climate in the lake's fluvial and alluvial catchment, which includes large parts of northern Israel and Lebanon and southwestern Syria. The study sheds light on topics such as changes in olive cultivation through time and regions, processes of urbanization and collapse and settlement expansion and retraction in the arid zones.

During the application of a winter water restriction in the seasons of 2011 and 2012, was quantified and related
the water status of olive (Olea europaea L.) with soil moisture content and ambient temperature. The experiment
was conducted in olive trees cv. Arbequina 10 years old in EEA San Juan INTA (San Juan, Argentina).
The treatments were: T1, full irrigation with replacement of 100% of crop evapotranspiration (ETc) throughout
the cycle and two treatments with water restriction (21 June to 31 August), T2, irrigated with 50% ETc and T3,incluno-
irrigation, for the rest of the season with irrigation were 100% ETc. The stem water potential (Ψtallo), stomatal
conductance (gs), relative extractable water (REW) soil and the effect of ambient temperature were measured.
The results demonstrated the feasibility in implementing winter water restrictions in the arid region of Argentina,
with low water availability during that period. The decrease in Ψtallo and gs depends on the content REW of
soil and ambient temperatures. Applying a water restriction which replaces the 50% ETc, with an initial reserve
of easily available water (AFA) of 40 mm, slightly affects the water status of the olive tree; while implementing
a full irrigation restriction during the winter, without initial reserve of AFA, severely affects the Ψtallo and gs to
-6.80 MPa and 5.67 mmol/m²/s, respectively. Irrigation scheduling during the winter using Ψtallo and gs must be
evaluated together with the soil moisture content.

The effects of NaCl salinity on the growth, ion content and gas exchange of six olive (Olea europaea L.) cultivars (Koroneiki, Mastoidis, Kalamata, Amphissis, Kothreiki and Megaritiki) were studied. The plants were grown in 8.5 l pots containing sand-perlite mixture (1:3) for 5 months and were irrigated with half-strength Hoagland solution containing 0, 25, 50, 100 and 200 mM NaCl. Shoot length was reduced significantly above 25 mM for cvs Koroneiki, Kalamata and Megaritiki and above 50 mM NaCl for the others. Total plant leaf area was reduced significantly above 25 mM NaCl, reaching 85% at 200 mM NaCl for the cvs Mastoidis and Amphissis, due to defoliation. At high salinity the aerial part of the plants was more depressed than the root. The concentration of Na and Cl (% d.w.) was higher in roots than in other parts of the plant (shoots and leaves), and increased with the increase of salinity. In Kalamata, leaf Na and Cl concentration was very low for all salinity treatments. Salt injury symptoms (leaf tip burning) appeared in Koroneiki, Amphissis and Mastoidis at 100 mM NaCl, becoming more severe at 200 mM due to defoliation. The cultivars Kothreiki and Megaritiki at 200 mM NaCl exhibited only a few symptoms, while in Kalamata no any injury was observed. Assimilation rate of CO 2 and stomatal conductance were significantly reduced at high salinity levels in all cultivars. Gas exchange in the leaves was not highly correlated with chloride and sodium contents in all cultivars. Kalamata showed higher resistance to salinity, followed by Megaritiki and Kothreiki. Inferences on the mechanisms of action of salt on olive trees are discussed. #

Extra-Virgin Olive Oil (EVOO) is a fundamental component of the Mediterranean diet and it may contain several anti-oxidant substances, such as phenols. Previous research has shown that this food may be enriched in phenols by spraying a sodium-selenate solution (100 mg L-1 Se) onto the crop canopy before flowering. The aim of this research was to evaluate the effect of this Se-fertilization before flowering (cv. Leccino) on the phenolic profile of EVOOs, and test to what extent such effects depend on the weather pattern, as observed in two contrasting experimental seasons (2013 and 2014). Results showed that Se-fertilisation enriched EVOOs both in selenium (up to 120 μg kg-1) and in phenols (up to 401 mg kg-1). This latter enrichment was related to an increase in PAL (L-Phenylalanine Ammonia-Lyase) activities and it was largely independent on the climatic pattern. Considering the phenolic profile, oleacein, ligustroside, aglycone and oleocanthal were the most affected compounds and were increased by 57, 50 and 32%, respectively. All these compounds, especially olea-cein, have been shown to exert a relevant anti-oxidant activity, contributing both to the shelf-life of EVOOs and to positive effects on human health. It is suggested that Se-fertilisation of olive trees before flowering may be an interesting practice, particularly with poor cultivars and cold and rainy weather patterns, which would normally lead to the production of EVOOs with unfavourable phenolic profile.

Olive (Olea europaea) trees in the arid Negev Desert of southern Israel are important relicts on the ancient agricultural landscape. Among them are a cluster of several trees located in Wadi Zetan, at the heart of the Shivta horticulture terroir, with its abundant agricultural runoff remains. Two isolated olive bearing trees stand in a sheltered beneath cliff in the upper part of the wadi. Radiocarbon dating of an internal part of the trunk of one of these living trees estimates its minimum age as the mid-16th-early 17th century CE (~500 years old). Archaeological excavations conducted beneath the trees and the adjacent dam revealed OSL samples of loess accumulation dated to the Early Islamic period (8th-9th centuries CE). The stratigraphy and chronology of this sediment deposition indicate its rapid and short accumulation. Palynological analysis of the same OSL dated samples indicates that grapevines and olive trees were cultivated in the immediate vicinity of the site during the Early Islamic period. The lack of pollen of cultivated taxa from the latter part of the sequence points to cessation of the agricultural activity, probably a few hundred years later. Leaf samples for DNA profiling of the trees in comparison to other local old olive trees around the country, indicate that the trees in Wadi Zetan are genetically close to a known cultivar common among ancient olive trees. The trees have survived for at least a few hundred years, in an arid area, due to the local conditions and enhanced drainage from the man-made upper runoff system. These old olive trees bear a powerful and symbolic significance, indicating the endurance and sustainability of ancient desert runoff agriculture. Moreover, the survival of their relicts in Wadi Zetan suggests their potential as cultivars greater resilience to the harsh growing conditions of arid environments.

Production and disposal of olive-mill wastes represent a problem of environmental relevance particularly in the Mediterranean countries where they are generated in huge quantities. A field trial was carried out to evaluate the short-term effects of soil amendment with solid olive mill waste (OMW) and its compost in comparison to the olive mill waste derived from the new two-phase treatment (humid OMW) and its resulting compost. The impact of treatments on soil water extractable organic matter and soil microbiota was determined. During a 120 days-long field trial, it was observed an initial increase of water extractable organic carbon (WEOC), total reducing sugars and total phenol compounds for all the amended soils. Even if humid OMW had the highest WEOC and total phenol compounds concentration, it increased to a lesser extent their content in the soil, probably due to the rapid utilisation of this particular organic matter by microorganisms. After three days from spreading, all amendments induced rapid modifications of both fungal and bacterial communities. However, while the bacterial community restored its initial state at the end of the trial, suggesting their high resilience capacity, the fungal populations changes remained until 120 days. The overall results indicated that all types of the organic materials tested as soil amendments had an impact on the soil microbial communities, especially in the early days of the field trial, without negative effects on the soil chemical characteristics.

The genus Olea contains about 30 species split into three subgenera, Tetrapilus, Paniculatae, and Olea (cultivated olive and wild relatives), found in Asia, Australia and Asia, Africa and Europe, respectively. The species O. europaea L. includes six subspecies: Olea europaea L. ssp. europaea (the Mediterranean olives); O. e. laperrinei (distributed in Saharan massifs of Hoggar, Aïr, Jebel Marra in Algeria); O. e. cuspidata (which moved from South Africa to Egypt, East Australian areas and Hawaii, and from Arabia to northern India and Southwest China); O. e. guanchica (Canary Islands); O. e. maroccana (southwestern Morocco); and O. e. cerasiformis (Madeira). Using molecular markers, it has been ascertained that the Mediterranean olives include the cultivated types (O. europaea L. ssp. europaea var. sativa), the true wild oleaster (O. e. e. var. sylvestris), and the feral form olevaster from seedlings born from seeds of the cultivated types. The oleaster has a narrow range of distribution and it is often mistaken for olevaster. Recolonization of Oleaster of the Mediterranean basin occurred after the last glacial event, from refuges located in both eastern and western Mediterranean basin areas toward southern Europe. Oleaster is a source of rootstock for propagating new improved cultivated varieties. Cultivated and wild forms have the same diploid chromosome number (2n = 46) and are fully interfertile. Triploid and tetraploid genotypes have been isolated from cultivated O.e.e., but polyploid forms have been found in endangered natural populations of O. e. guancica (tetraploid) and O. e. maroccana (hexaploid). Individual oleaster trees showing superior performance for size and/or oil content of fruit were selected empirically during olive domestication and propagated vegetatively as clones using cuttings that were planted directly or, more recently, grafted onto indigenous oleasters. Genetic markers linked to the most important agronomic traits, such as size of the tree, content of secondary products of fruit, flowering induction, oil quality, and biotic and abiotic resistance, will help introgression by conventional breeding of oleaster trait-enhancing genes into cultivated olive. Successful results were difficult to achieve due to both the complex genetic basis of the traits to be improved and the long juvenile period of the progenies that delays the expression of the target traits. In vitro techniques to regenerate doubled haploids from hybrids or somaclonal variation induction may complement classical breeding procedures. Genetic transformation could speed up the development of new genotypes, and transgenic olive plants with modified growth habit and putative induced disease resistance are being tested under filed conditions. However, the development of an efficient regeneration method from mature tissue is the limiting factor for the routine application of this technology to olive genetic improvement.

Key message This work demonstrates that the Olive tree, which is managed and pruned as a fruit tree, can be treated as a forest tree using allometric equations, to estimate both biomass production and volumes. Abstract The Olive tree (Olea europaea L.) is an evergreen tree that can grow and accumulate a relatively high amount of dry matter, even in dry environmental conditions common in the Mediterranean basin and typical of traditional rain-fed agriculture. The objective of this research was to develop a tool to predict woody biomass and tree component volume for the olive tree, to be used for different agricultural and environmental purposes. The study was carried out in six olive groves across three locations in Italy, collecting data on the ''Leccino'' cultivar, which is spread worldwide. Models for volume and biomass were developed for the whole tree and its different components. Basal diameter and a diameter of 80 cm of the trunk height were explored as independent variables for modeling. The results of this study demonstrate a high correlation between the two selected variables and total biomass, above and below-ground biomass and tree component volumes. The same variables show high correlation with total leaf area, but no correlation with the root/shoot ratio, and Leaf Area Index. Keywords Woody biomass Á Tree component volume Á Olea europaea Á Allometric relationship Á ''Leccino'' cv