Mature Olive Trees Research Articles

Enhancing the Yield of Mature Olive Trees via Comparative Fertilization Strategies, including a Foliar Application with Fulvic and Humic Acids, in Non-Irrigated Orchards with Calcareous and Non-Calcareous Soils

This study investigated the impact of fertilization treatments on mature, forty-year-old, fully productive olive trees (Olea europaea L. cv. Koroneiki) in two non-irrigated orchards featuring contrasting soil types: non-calcareous–acidic and calcareous–alkaline. Over three years (2019–2021), seven distinct treatments were applied, involving inorganic soil fertilizers (traditional strategy) and foliar applications of a liquid organic product containing fulvic and humic acids. Fertilization significantly influenced physiological parameters, such as mineral nutrition, photosynthetic pigments of olive leaves, fruit yield, and oil production per tree, revealing noteworthy effects influenced by soil types and their interactions with treatments. Statistical analysis highlighted specific treatments, indicating that the foliar application of the organic product once a year in alkaline soil or biannually in acidic soil resulted in the highest observed fruit yield and oil production per tree. Indeed, contrary to the control–unfertilized trees, specific fertilization strategies resulted in an average increase of up to 47% and 73% in fruit yield per tree and up to 96% and 100% in oil production per tree in acidic and alkaline soil, respectively. Furthermore, consistently high yields were correlated with constant high values of the chlorophyll a/chlorophyll b ratio (2.3–3.3 in August for acidic soil) and leaf chlorophyll a concentration (55–66 mg/100 g f.w. in August for alkaline soil). This novel finding underscores the crucial role of these factors as prerequisites for achieving superior fruit production. Our results emphasize the potential of integrating foliar organic fertilization as a complementary strategy to traditional soil-based approaches. This is particularly relevant under non-irrigated/rainfed cultural conditions, emphasizing the significance of considering alternative fertilization practices for optimized olive orchard management.

Olive Tree Physiology and Productivity Responses under No-Tillage or Digestate Amendment in an Acid Clay Soil

In Mediterranean countries characterized by increasingly extended hot and dry periods, olive trees are often conventionally practiced in low fertility and rainfed soils. This study investigated over a 15-month period how conventional tillage, combined with or without incorporated solid digestate, and no tillage affected selected soil properties, photosynthetic activity and productivity of mature olive trees growing in highly clayey acid soil with an unbalanced nutrient content and Mn excess. Neither in soil nor in drupes were Mn, Fe, Cu and Al contents affected by the managements. However, in soil, exchangeable Mn that was always larger than 200 mg kg−1 threshold and unbalanced Ca, Mg, and K contents were evidenced in all treatments. Non-tilled soil showed the highest (p < 0.05) stomatal conductance and photosynthetic rate, and the highest (p < 0.05) fruits and oil yields. Instead, conventional tillage negatively (p < 0.05) affected plant physiology and productivity, likely due to the tilled increase in aeration, enhancing soil water loss and organic C mineralization. Conversely, digestate addition increased TOC, TN and EC. Stomatal conductance, the photosynthetic rate and plant yield significantly recovered (albeit not to no-tillage values) in tillage combined with incorporated digestate, suggesting that digestate-derived organic matter created soil conditions less constraining to plant growth and productivity than the conventional tillage did. Dealing with soil properties and climatic conditions is the key for adopting the best management practice for preserving plant productivity and soil fertility.

Influence of Experimental Warming on the Rate and Duration of Fruit Growth and Oil Accumulation in Young Olive Trees (cvs. Arbequina, Coratina).

Olive tree cultivation in new warmer areas and climate change have increased the global interest in understanding how air temperature affects both fruit growth and oil accumulation. The aims of this study were to evaluate the rate and duration of fruit growth and oil accumulation in response to experimental warming (+3) in a semiarid region of Argentina; and assess how warming affected fatty acid composition. Young, potted olive trees (cvs. Arbequina, Coratina) were warmed (T+) or maintained near ambient temperature (T0) inside open top chambers in the field during oil accumulation in 2014-2015 or 2015-2016 using different trees in each season. Warming reduced the rate of both fruit growth and oil accumulation in T+ compared to T0 in both cultivars. These rate reductions under T+ led to large decreases in final fruit dry weight and oil concentration. In contrast, the durations (i.e., days) of fruit growth and oil accumulation were most often not affected. Cultivar x temperature interactions were observed in 2014-2015 with warming decreasing oleic acid and increasing linoleic acid in cv. Arbequina, while cv. Coratina showed no response to warming. However, no interactions were found in 2015-2016. Studying how fruit growth and oil accumulation respond to adaptation strategies against increasing air temperatures should be a priority in both young and mature olive trees of numerous cultivars given crop expansion to new regions and future climate scenarios.

To -8 MPa and back: in-situ annual water relation in non-irrigated olive trees

Olive trees are known for their capability to endure and recover from low stem water potentials (Ψstem < -6 MPa) and even maintain substantial gas exchange under such conditions. In the current experiment, we tested the physiological responses of mature olive trees in-situ while enduring such Ψstem under field conditions for seven months of rainless Israeli summer. To characterize olive trees' seasonal response to drought, we followed the annual patterns (a measurement day once a month) of Ψstem, gas exchange, osmotic adjustment, and hydraulic conductance of mature bearing olive trees that were disconnected from irrigation. We found that through the dry summer, the trees gradually dehydrated to a minimum of -8.1 MPa in October. An increase of 1320 mmol/kg in the leaf osmotic concentration through the summer was part of the tree's acclimation to the low Ψstem. Surprisingly, despite the low Ψstem that have probably led to substantial xylem cavitation, the trees maintained stomatal conductance of at least 0.023 mol m-2 s-1 and positive assimilation throughout the year. Following the winter rains, the plants recovered their Ψstem, gas exchange, and hydraulic conductance to maximal values. The results demonstrate olives' remarkable ability to tolerate Ψstem while maintaining above minimal gas exchange and producing fruits.

Using Visible and Thermal Images by an Unmanned Aerial Vehicle to Monitor the Plant Water Status, Canopy Growth and Yield of Olive Trees (cvs. Frantoio and Leccino) under Different Irrigation Regimes

An efficient management of water relies on the correct estimation of tree water requirements and the accurate monitoring of tree water status and canopy growth. This study aims to test the suitability of visible and thermal images acquired by an unmanned aerial vehicle (UAV) for monitoring tree water status and canopy growth in an irrigation experiment. We used mature olive trees of two cultivars subjected to full irrigation, deficit irrigation (41–44% of full irrigation), or rainfed conditions. Deficit irrigation had limited or no effect on fruit and oil yield. There was a significant relationship between the remotely sensed crop water stress index derived from thermal images and the stem water potential (R2 = 0.83). The RGB images by UAV allowed to estimate tree canopy volume and were able to detect differences in canopy growth across irrigation regimes. A significant relationship between canopy volume and LAI was found for both cultivars (R2 of 0.84 and 0.88 for Frantoio and Leccino, respectively). Our results confirm the positive effects of deficit irrigation strategies to save relevant volumes of water and show that aerial images from UAV can be used to monitor both tree water stress and its effects on canopy growth and yield.

Mitigation of High-Temperature Damage by Application of Kaolin and Pinolene on Young Olive Trees (Olea europaea L.): A Preliminary Experiment to Assess Biometric, Eco-Physiological and Nutraceutical Parameters

Various products are used to mitigate the negative effects of abiotic stress in olive trees. The aim of the research was to examine an anti-transpirant product (Vapor Gard®, V) and a kaolin- based product (Manisol, K) effect on the growth of two-year-old olive tree seedlings under high temperature. The study was conducted in a greenhouse on trees of a native cultivar of Campania (cv. Salella) grown in pot during the growing season from May to September 2020. The experimental design included two products: di-1-p-menthene (product V) and kaolin (product K), applied five times at 20 day intervals compared with a control. The following biometric, physiological, and nutraceutical parameters were evaluated: stomatal conductance, chlorophyll a fluorescence, Soil Plant Analysis Development (SPAD) index, relative water content (RWC), shoots growth, total leaf area per plant, trunk cross-sectional area, dry matter partitioning, total polyphenols, and antioxidant activity. The results obtained showed that the application of di-1-p-menthene (V) was able to induce a significant improvement of shoots growth (+37.22%) and trunk cross-sectional area (+46.60%) and a reduction of the stomatal conductance and an increase of leaf RWC values. Application with kaolin had positive effects on the total polyphenol content, with an increase over the control of 240.33% and higher antioxidant activity values. Further studies are necessary to determine the effect of these products on the biometric, physiological and nutraceutical parameters of mature olive trees cultivated in open field conditions.

Canopy re-establishment after severe winter cold damage of mature olive (Olea europaea L.) trees cultivars ‘Blaidy’ and ‘Mission’ grown under Tehran environment condition

Canopy re-establishment after severe winter cold damage of mature olive (<i>Olea europaea</i> L.) trees cultivars ‘Blaidy’ and ‘Mission’ grown under Tehran environment condition

Root adaptation of urban trees to a more precise irrigation system: Mature olive as a case study

Water scarcity encourages municipalities to use more precise irrigation systems in arid urban landscapes. However, major concerns are associated with the adaptation of mature trees to new irrigation systems after they have matured under traditional management. We investigated the adaptation of mature olive trees to a change in irrigation system from a traditional surface to an automatic drip irrigation system in a coarse-textured urban forest park. The growth indices of eight-year-old olive trees were monitored for the period of 2012–2014 under three irrigation systems: (1) automated drip irrigation (ADI) for trees that matured under traditional basin-surface irrigation (TSI), (2) TSI since plantation, and (3) traditional drip irrigation (TDI) irrigating the trees depending on water availability since the time of planting. We additionally determined the spatial pattern of root development by collecting 156 soil samples from each irrigation system with a 20 × 20-cm grid system (120 cm width × 80 cm depth) in the soil profile. Results showed no significant differences in terms of fruit productivity between TSI and recently established ADI systems. Automated drip irrigation resulted in the maximum root density with a uniform root distribution pattern, where roots expanded all over the soil profile. In TSI, however, the roots were distributed irregularly, with the highest density close to the irrigation basin. The wide spacing between drippers in the TDI system created large gaps between the wetted zones in the soil with a low water-holding capacity, leading to a discrete small root system. The present study highlights the positive response of mature olive trees to the replacement of the irrigation system in an urban forest park with limited available water and low soil quality. Our findings will help municipalities to properly preserve mature urban trees and the ecosystem services for their inhabitants.

Root structural plasticity enhances salt tolerance in mature olives

Roots are the first plant organ to encounter, sense, and respond to soil salinity. Like for many moderately salt tolerant species, roots of olive (Olea eurpaea) trees are the principal players in salt tolerance. We studied roots of mature olive trees in order to illuminate the yet vague mechanism(s) of root salt exclusion.Root structural traits were examined in olive trees grown in lysimeters and from a long-term salinity field trial. The distribution of salts was detected in root cross-sections using scanning electron microscopy combined with energy dispersive spectroscopy.Increased soil salinity caused a continuous decline in specific root length and an increase in root diameter, periderm thickness, and specific hydraulic conductivity. While periderm cell number was not modified, cell diameter increased linearly by a total of 50 % as root zone salinity increased nearly eight-fold. Strong compartmentation of Na within the periderm was found, with highest content in the outer periderm layer and lowest content in the stele. Increase in soil salinity was associated with decrease in stele area, yet, hydraulic conductivity was doubled due to higher fraction of large diameter xylem vessels.Our results indicate significant root structural plasticity, which underlies the salt resistance mechanisms. The dominant trait enabling salt tolerance of olive trees is the enlarged periderm serving as an apoplastic barrier that enhances salt compartmentation and exclusion from the vascular tissues.

First Report of Root Rot Caused by Phytophthora bilorbang on Olea europaea in Italy.

Leaf chlorosis, severe defoliation and wilt associated with root rot were observed on mature olive trees cv. Nera di Gonnos in an experimental orchard at Mirto Crosia (Calabria, southern Italy). An oomycete was consistently isolated from rotten roots of symptomatic olive trees. It was identified as Phytophthora bilorbang by morphological characters and sequencing of Internal Transcribed Spacer (ITS) regions of ribosomal DNA (rDNA). Pathogenicity was verified by inoculating potted two-month-old rooted cuttings of Olea europaea var. Nera di Gonnos in a soil infestation trial. P. bilorbang was re-isolated from roots of symptomatic, artificially inoculated olive cuttings to fulfill Koch’s postulates. This is the first report of P. bilorbang on O. europaea L. and on a species of the Oleaceae family worldwide.

Olive Twig and Branch Dieback in California Caused by Cytospora oleicola and the Newly Described Species Cytospora olivarum sp. nov.

Field surveys conducted throughout California olive-growing regions in 2008 and 2009 resulted in a collection of 101 Cytospora-like isolates from olive twig and branch dieback symptoms. Cytospora isolates were isolated from multiple cvs. in different olive orchards in Fresno, Madera, Merced, Napa, Riverside, Santa Barbara, Sonoma, Tulare, and Ventura counties. Taxonomic studies of macro- and microscopic structures along with multigene phylogenetic analyses of the internal transcribed spacer region, including the 5.8S rDNA (ITS1-5.8S-ITS2), and fragments of the translation elongation factor 1-α, beta-tubulin, and actin genes identified two species, Cytospora oleicola and C. olivarum sp. nov. Pathogenicity studies conducted in mature olive trees cvs. Manzanillo and Sevillano showed both species to be pathogenic and able to cause vascular necrosis and cankers in olive branches. This study adds to the current knowledge on the etiology of olive twig and branch dieback and provides new important information for the development of effective control strategies against canker diseases affecting olive in California.

Nitrogen status affects growth, chlorophyll content and infection by Fusicladium oleagineum in olive

Olive leaf spot, caused by Fusicladium oleagineum, is the most common foliar disease in olive (Olea europaea L.). The influence of nitrogen fertilization on olive spot development was evaluated on the susceptible cultivar ‘Picual’ in hydroponic culture, potted plants and mature olive trees. Two levels of nitrogen, using different solutions of Ca(NO3)2, KNO3, NaNO3 and urea, were applied. Shoot growth, and leaf chlorophyll and nitrogen concentration were assessed. Plants or detached leaves were artificially inoculated with a conidial suspension of the pathogen. A significant increase in shoot growth, chlorophyll and nitrogen concentration in leaves and disease incidence was observed in plants subjected to a high nitrogen treatment. However, plants with low nitrogen level reached a reduction of 59%, 55%, 42% and 65% in these parameters, respectively. This study shows that nitrogen fertilization management may aid in reducing olive leaf spot development.

Technical Efficiency of Olive-growing Farms in the Northern West Bank of Palestine

This study examines the firm-level technical efficiency of olive-growing farms in the West Bank of Palestine. Using a sample of 176 olive farms in the Jenin governorate collected during September 2015, we estimated the Cobb-Douglas stochastic frontier production function. The results suggest that higher levels of education of the head of farm households and farms with a higher density of olive trees are associated with higher technical efficiency. The introduction of irrigation had a marginal effect on upgrading efficiency. Enlarging the irrigated area had a negative effect, but increasing the number of years of irrigation had a positive impact on efficiency. While the impact of access to export markets on technical efficiency was negative and farms oriented towards domestic consumption of olive oil showed lower efficiency, access to markets through olive presses and middlemen contributed to improve efficiency. The results of the chosen half-normal model suggest that olive farms in Jenin have the potential to increase production by 51.4% through more efficient use of technology and production inputs. These results imply promotion of intensive farming with mature olive trees and expansion of market access could contribute to improve technical efficiency of olive farms in the West Bank even under severe geographical and geopolitical conditions.

Changes in key photosynthetic parameters of olive trees following soil tillage and wastewater irrigation, modified olive oil quality

The use of wastewater (WW) provides a reliable source of water and nutrients for crop production. Soil tillage is one of the key soil management practices in agricultural land use. In the present study, we studied the effects of these two agricultural practices on key physiological parameters of olive trees and on olive oil quality. The experiment was carried out on mature olive trees (Olea europaea L. cv. Chemlali). Two tillage practices treatments (Trees grown in Tilled soil: TTS; and Trees grown in No-tilled soil: TNTS) were combined with two irrigation treatments (Trees irrigated with WW: IT; and Trees grown under rainfed condition: TRC) during two successive years (2013 and 2014). Statistical analyses demonstrated that the factor “soil tillage” was more efficient in improving photosynthetic parameters of olive trees than WW irrigation. The combination of soil tillage with WW irrigation improved significantly leaf chlorophyll fluorescence parameters, stomatal conductance, transpiration and chlorophyll content, which closely associated with an increase of photosynthetic rate, and a decrease of stress metabolites (leaf phenolic compounds and carbohydrates). On the other hand, a decrease of key photosynthetic parameters and an accumulation of stress metabolites in leaves were observed when combining rainfed condition and No-tilled soil. WW irrigation affected negatively the oxidative stability and nutritional value of olive oil, especially by decreasing the contents of antioxidant compounds (total phenols and pigments) and the levels of MUFA, C18:1, C18:3 and elevating SFA and PUFA contents. However, soil tillage combined with TRC improved oil stability to oxidation and its nutritional value by increasing the contents of antioxidant compounds and the levels of MUFA and C18:1, as well as C18:1/C18:2 and MUFA/PUFA ratios.The results of this study prove that, under water scarcity conditions, wastewater irrigation in oleiculture should be combined with soil tillage and recommended only in the ‘Off’-year to support vegetative growth and improve physiological performance of olive trees. In the ‘On’-year, tilling the soil under rainfed conditions proved to be the most favorable cropping strategy for enhancing both physiological performance of olive trees and olive oil quality. These findings must be taken into consideration when developing strategies for oil quality enhancement, mainly in an exporting country like Tunisia.

Low winter temperatures induce a disturbance of water relations in field olive trees

Low winter temperatures induce an increase in the soil-to-trunk hydraulic resistance of field-grown olive trees resulting in a significant disturbance of their water relations. A disturbance of water relations in response to chilling have long been observed in potted plants growing under controlled conditions, but information is lacking for field plants. The aim of this study was to assess the effects of winter low temperatures on the water relations of mature olive trees. To this end, water potential, sap flux density, soil temperature and meteorological data were monitored in a hedgerow olive orchard near Córdoba, southern Spain, throughout two consecutive winters. Water stress symptoms were found in terms of midday Ψ, despite adequate water supply and low evaporative demand. These effects were associated with changes in the soil-to-trunk hydraulic resistance (R root), which increased by December–January to much higher values than those previously reported in the literature, particularly in the year of higher fruit load. The contribution of viscosity (η) to the observed R root dynamics was almost negligible as deduced from measurements of soil temperature, so the high winter values of R root were likely to have originated from other causes such as reductions in membrane permeability and root growth. The findings of this work raise new major issues that deserve further research such as the impact of the winter water stress on stomatal conductance and photosynthesis rates in mature olive trees.

Using band dendrometers in irrigation scheduling: Influence of the location inside the tree and comparison with point dendrometer

Trunk diameter fluctuation parameters have been common indicators in water relations experiments. In most fruit trees, these parameters have been reported as very sensitive to drought conditions. However, the great variability of the measurements, amongst other factors, has limited their use in commercial orchards. One of the sources of error could be the location of the sensors on the tree, which has been poorly studied. In addition, almost all the studies in horticultural science have been performed with point dendrometers, while in forest research band and point dendrometers have been used. The aims of this work were (i) evaluate the influence of band dendrometers location on mature olive trees (branch or trunk, experiment 2011, and (ii) compare the feasibility of them with point dendrometers (experiment 2012). Wireless Sensor Network band dendrometers were installed in 5 trees during 2011 in the main trunk and in branches. Trunk growth rate (TGR) and maximum daily shrinkage (MDS) were compared in both locations. Individual TGR data of these trees were all around the line 1:1 in the relationship between trunk and branch. Individual MDS data in stressed trees were significantly higher than the line 1:1 in the branch vs trunk relationship. The non-stressed MDS data, however, were not significantly different to this line. During 2012, band and point dendrometers were installed in the main trunk of 3 trees. The location did not affect the values of the indicators in non-stress conditions, but significant changes were found in MDS of stressed trees. The relationship between band and point dendrometer was probably affected by the variability of the trunk itself.

Vulnerability to cavitation in Olea europaea current‐year shoots: further evidence of an open‐vessel artifact associated with centrifuge and air‐injection techniques

Different methods have been devised to analyze vulnerability to cavitation of plants. Although a good agreement between them is usually found, some discrepancies have been reported when measuring samples from long-vesseled species. The aim of this study was to evaluate possible artifacts derived from different methods and sample sizes. Current-year shoot segments of mature olive trees (Olea europaea), a long-vesseled species, were used to generate vulnerability curves (VCs) by bench dehydration, pressure collar and both static- and flow-centrifuge methods. For the latter, two different rotors were used to test possible effects of the rotor design on the curves. Indeed, high-resolution computed tomography (HRCT) images were used to evaluate the functional status of xylem at different water potentials. Measurements of native embolism were used to validate the methods used. The pressure collar and the two centrifugal methods showed greater vulnerability to cavitation than the dehydration method. The shift in vulnerability thresholds in centrifuge methods was more pronounced in shorter samples, supporting the open-vessel artifact hypothesis as a higher proportion of vessels were open in short samples. The two different rotor designs used for the flow-centrifuge method revealed similar vulnerability to cavitation. Only the bench dehydration or HRCT methods produced VCs that agreed with native levels of embolism and water potential values measured in the field.

Simultaneous measurements of stem radius variation and sap flux density reveal synchronisation of water storage and transpiration dynamics in olive trees

AbstractContinuous stem water relations, sap flux and radial variation, and soil moisture were monitored in rainfed and irrigated mature olive (Olea europaea L.) trees in field conditions in central Italy. A mathematical procedure was applied to describe plant–environment dependences in order to facilitate the identification of the correspondence between stem factors (sap flow and diameter variation) and environmental parameters (water availability and evaporative demand). A direct correspondence between the time series of the monitored parameters was observed in the two growing seasons. Soil water content was synchronous to stem diameter variation in irrigated trees, whereas they were asynchronous in rainfed conditions. On a daily basis, sap flux density showed an opposite trend with respect to patterns of vapour pressure deficit and evapotranspiration (ET0) in spring, corresponded to the course of ET0 in summer and lagged behind ET0 in autumn. Maximum daily shrinkage was correlated with vapour pressure deficit (R2 = 0.50, in rainfed; R2 = 0.51, in irrigated plants), whereas it was not significantly related to ET0. Conversely, cumulative sap flow showed a good relationship with ET0 (R2 = 0.60, in rainfed; R2 = 0.51, in irrigated plants) and scaled exponentially with maximum daily shrinkage (R2 = 0.56, in rainfed; R2 = 0.61, in irrigated plants), indicating consistent radial transfer of water between xylem and phloem. The proposed analytical approach highlights the importance of combining measured parameters and sensor outputs in order to determine adjustments of specific plant functionality traits, such as the dynamics of water status in trees, for modelling and practical uses. This study also indicates a different accounting of the effect of microclimatic variables on plant signals based on stem sensors. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Aboveground respiratory CO2 effluxes from olive trees (Olea europaea L.)

The accurate assessment of respiration by woody vegetation, still a challenge in plant produc- tivity models, is generally a problem of correctly scaling-up the process from organs to the whole plant. We used a large (41.6 m 3 ), canopy chamber to enclose mature olive trees and to measure aboveground respiration (Rag) under natural environmental condi- tions in an irrigated olive orchard in Cordoba (Spain). The 3-year study assessed nocturnal and seasonal Rag patterns in terms of temperature (T), plant dry matter composition, and phenology. The relative contribu- tions of maintenance and growth respiration to Rag were determined empirically via an independent experiment. Although short-term variations in Rag rates were explained mainly by T variations, over seasonal time-scales this relationship was modu- lated by the vegetative composition of the olive trees and the contribution of growth respiration to Rag when the plants, in different seasons, allocated most of the new assimilates to actively growing shoots, flowers or fruits. Leaf mass and fruit load were the main determinants of Rag ,w hich was weakly affected by differences in woody biomass since woody tissue respiration accounted for just 15 % of Rag. Respiration in olive trees during fruit setting periods is composed of approximately 30 % growth and 70 % maintenance. This study provides an independent evaluation of how, and to what degree, seasonally varying plant organ composition determines total respiration. Improved modelling of ecosystem respiration can be achieved by account- ing for plant biological patterns characterising energy-requiring growth and maintenance pro- cesses, since biochemical kinetics alone cannot explain the observed seasonal variability.

Shoot hydraulic characteristics, plant water status and stomatal response in olive trees under different soil water conditions

To evaluate the impact of the amount and distribution of soil water on xylem anatomy and xylem hydraulics of current-year shoots, plant water status and stomatal conductance of mature ‘Manzanilla’ olive trees. Measurements of water potential, stomatal conductance, hydraulic conductivity, vulnerability to embolism, vessel diameter distribution and vessel density were made in trees under full irrigation with non-limiting soil water conditions, localized irrigation, and rain-fed conditions. All trees showed lower stomatal conductance values in the afternoon than in the morning. The irrigated trees showed water potential values around −1.4 and −1.6 MPa whereas the rain-fed trees reached lower values. All trees showed similar specific hydraulic conductivity (K s) and loss of conductivity values during the morning. In the afternoon, K s of rain-fed trees tended to be lower than of irrigated trees. No differences in vulnerability to embolism, vessel-diameter distribution and vessel density were observed between treatments. A tight control of stomatal conductance was observed in olive which allowed irrigated trees to avoid critical water potential values and keep them in a safe range to avoid embolism. The applied water treatments did not influence the xylem anatomy and vulnerability to embolism of current-year shoots of mature olive trees.