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Introduction: The use of treated municipal wastewater (TWW) represents a relevant opportunity for irrigation of agricultural crops in semi-arid regions to counter the increasing water scarcity. Pharmaceutically active compounds (PhACs) are often detected in treated wastewater, posing a risk to humans and the environment. PhACs can accumulate in soils and translocate into different plant tissues, reaching, in some cases, edible organs and entering the food chain. Methods: This study evaluated the uptake and translocation processes of 10 PhACs by olive trees irrigated with TWW, investigating their accumulation in different plant organs. The experiment was conducted in southern Italy, in 2-year-old plants irrigated with three different types of water: freshwater (FW), TWW spiked with 10 PhACs at a concentration of 200 µg L-1 (1× TWW), and at a triple dose (3× TWW), from July to October 2021. The concentration of PhACs in soil and plant organs was assessed, collecting samples of root, stem, shoot, leaf, fruit, and kernel at 0 (T0), 50 (T1), and 107 (T2) days of irrigation. PhACs extraction from soil and plant organs was carried out using the QuEChERS method, and their concentrations were determined by high-resolution mass spectrometry coupled with liquid chromatography. Results: Results of uptake factors (UF) showed a different behavior between compounds according to their physicochemical properties, highlighting PhACs accumulation and translocation in different plant organs (also edible part) in 1× TWW and 3× TWW compared to FW. Two PhACs, carbamazepine and fluconazole, showed interactions with the soil-plant system, translocating also in the aerial part of the plant, with a translocation factor (TF) greater than 1, which indicates high root-to-leaf translocation. Discussion: Findings highlight that only few PhACs among the selected compounds can be uptaken by woody plants and accumulated in edible parts at low concentration. No effects of PhACs exposure on plant growth have been detected. Despite the attention to be paid to the few compounds that translocate into edible organs, these results are promising for adapting wastewater irrigation in crops. Increasing knowledge about PhACs behavior in woody plants can be important for developing optimized wastewater irrigation and soil management strategies to reduce PhACs accumulation and translocation in plants. [ABSTRACT FROM AUTHOR]

Background: A modified version of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method has been tested for quantifying six active compounds of pharmaceuticals (PhACs), i.e., two different antibiotics, two anti-inflammatories, one antifungal, and one anti-depressant, extracted from roots, leaves and stems, pulp, pits, and oil obtained from olive trees. The different matrices have been polluted with all contaminants at 25, 50, and 250 µg L−1 and the recoveries were determined by liquid chromatography tandem–mass spectrometry. The validation of the method has been carried out by determining linearity, recovery, precision, limits of detection (LODs), and limits of quantification (LOQs) values. A matrix-matched calibration for each matrix has been adopted in order to avoid the matrix effect at the aforementioned levels of fortification. Results: The recoveries of PhACs from the different matrices were always above 70% and the relative standard deviation (RSD) always ≤ 20%, conditions required for the validation of the method. The LOD and LOQ values were always lower than 25 µg L−1, i.e., always lower than the minimum concentration used in the experiment; therefore, the method can be validated at 25, 50, and 250 µg L−1. Conclusions: This method can represent a valid alternative to the traditional extraction methods to quantify pharmaceuticals extracted also from fatty matrices. [ABSTRACT FROM AUTHOR]

Aims: The conventional management adopted in many Mediterranean olive orchards makes them more vulnerable to climate change and attacks by pathogens, due to the decreased chemical plant defenses. In this scenario, a metabolomic analysis was carried out on the xylem sap (Xsap) of olive plants (Olea europaea L.) grown in the Salento peninsula (Italy). Methods: Trials were carried out in two olive groves, one organically and one conventionally managed (controls), successively both converted to sustainable management (i.e. frequent light pruning, soil and foliar fertilization, cover crops). The Xsap was extracted from the shoots of olive plants using a Scholander pressure chamber pressurized with N2 and gas chromatography-mass spectrometry metabolite profiling was performed in the Xsap. Results: An untargeted gas chromatography mass spectrometry (GC-MS) based metabolomic analysis of primary metabolites (including underivatized volatiles) of the Xsap revealed relative abundances of 153 identified metabolites and 336 unknown features across the 12 samples from four groups of samples. Among them, more than half were involved in the primary metabolism. Many of the compounds with increased levels under sustainable management (such as amino acids, soluble sugars, sugar alcohols) have a well-known role as osmoprotectants or are involved in plant defense, growth and development during stress or recovery stages. Conclusions: Sustainable management in olive groves can increase the ability of plants to overcome environmental stressors and enhance ecosystem balance. [ABSTRACT FROM AUTHOR]

Background: Beneficial bacteria-plant interactions play an important role in agriculture, positively affecting plant status and improving product quality. Bacterial endophytes contribute to host plant protection and survival. Aim: This study characterised the bacterial communities present in soil, leaf surface and xylem sap of olive trees, and investigated their response under a sustainable (Smng) or a conventional (Cmng) management system in an olive grove located in southern Italy. The aims are: (a) to understand if soil bacteria enter xylem and reach leaves and (b) to verify if the bacterial communities in the two management systems deeply differ due to the different agronomic practices applied in Smng and in Cmng. Methods: Therefore, a metagenomic approach was used to detect microorganisms, in order to estimate bacterial diversity and abundance, and to identify the bacterial taxa in the three analysed compartments in plants subjected to Smng and Cmng systems. Results: Bacterial communities came from the soil and reached aerial plant parts through xylem sap. The application of different agronomic practices influenced the composition of soil bacterial communities. Conclusions: The potential benefits of the specific bacterial taxa detected under the Smng system could improve plant growth protection and provide a higher crop quality in fruit plants. [ABSTRACT FROM AUTHOR]

Abstract: Olive tree (Olea europaea L.) is commonly grown under environmental conditions characterised by water deficit, high temperatures and irradiance levels typical of Mediterranean semi-arid regions. Measurement of gas exchange, chlorophyll content, chlorophyll fluorescence and photoinhibition was carried out on two-year-old olive trees (cv. ‘Coratina’) subjected to a 21-day period of water deficit followed by 23 days of rewatering. At the beginning of the experiment, plants were divided in to two groups and subjected to different light regimes: exposed plants (EP) under a mean photosynthetically active radiation (PAR) at mid-day of 1800μmolm−2 s−1 and shaded plants (SP) under a mean PAR of 1200μmolm−2 s−1. The effect of drought and high irradiance levels caused a reduction of gas exchange and photosystem 2 (PSII) efficiency, in terms of quantum yield of PSII (Φ PSII) both in EP and SP. Shading conditions allowed plants to maintain a high photosynthetic activity at low values of stomatal conductance, whereas in EP the reductions in photosynthetic efficiency and intrinsic water efficiency were due to non-stomatal components of photosynthesis. The decrease in photosynthetic activity and the increase of photoinhibition under drought were more marked in EP than in SP. Full sunlight caused in EP a higher non-photochemical quenching, whereas SP showed a better photochemical efficiency. The information here obtained can be important to understand the mechanisms by which olive plants can minimize photoinhibition when subjected to simultaneous abiotic stresses. [Copyright &y& Elsevier]

We evaluated the osmotic adjustment capacity of leaves and roots of young olive (Olea europaea L.) trees during a period of water deficit and subsequent rewatering. The trials were carried out in Basilicata (40°24' N, 16°48' E) on 2-year-old self-rooted olive plants (cv. ‘Coratina’). Plants were subjected to one of four drought treatments. After 13 days of drought, plants reached mean predawn leaf water potentials of –0.45 ± 0.015 MPa (control), –1.65 ± 0.021 (low stress), –3.25 ± 0.035 (medium stress) and –5.35 ± 0.027 MPa (high stress). Total osmotic adjustment increased with increasing severity of drought stress. Trees in the high stress treatment showed total osmotic adjustments ranging between 2.4 MPa at 0500 h and 3.8 MPa at 1800 h on the last day of the drought period. Osmotic adjustment allowed the leaves to reach leaf water potentials of about –7.0 MPa. Active osmotic adjustment at predawn decreased during the rewatering period in both leaves and roots. Stomatal conductance and net photosynthetic rate declined with increasing drought stress. Osmotic adjustment in olive trees was associated with active and passive osmotic regulation of drought tolerance, providing an important mechanism for avoiding water loss. [ABSTRACT FROM PUBLISHER]

The effects of water stress on water potential components, tissue water content, mean elastic modulus and the osmoregulation capacity of olive ( Olea europaea L. cv. Coratina) leaves was determined. Artificial rehydration of olive leaf tissues altered the P-V relationships so that a plateau phenomenon occurred. Points in the P-V curve in the region affected by the plateau, generally up to -0.5 MPa, were corrected for all the samples analyzed. In the corrected P-V relationship, an osmotic adjustment was found in drought-stressed leaf tissues. Osmotic potentials at full turgor (Ψ0 (sat)) and osmotic potential at turgor-loss (Ψ0 (TVT)) decreased from -2.06±0.01 MPa and -3.07±0.16 MPa in controls to -2.81±0.03 MPa and -3.85±0.12 MPa in most stressed plants. Osmotic adjustment values obtained from the P-V curves agreed with those obtained using an osmometer. An active osmotic adjustment of 1.42 MPa was also observed in 1–4 mm- diameter roots. Mannitol is the main carbohydrate involved in osmotic potential decrease in all treatments. The maximum elastic modulus increased from 11.6±0.95 MPa in the controls to 18.6±0.61 MPa in the most stressed plants. [ABSTRACT FROM AUTHOR]

In conventional olive growing, frequent soil tillage strongly reduces the complexity and diversity of the agro-ecosystem. Here, a metabolomic analysis was carried out on the xylem sap (XS) of olive plants (Olea europaea L.) from a grove located in Southern Italy (Basilicata region). The orchard has been divided in two plots that have been managed for 18 years with two different systems: a) 'sustainable management' (S mng), with no-tillage, fertigation and internal C-inputs (spontaneous weeds and pruning residues), and b) an adjacent rainfed 'conventional management' (C mng), that included soil tillage and mineral fertilization. The XS was extracted from olive shoots in two sampling times (ST1: May; ST2: October) using a Sholander pressure chamber, and its metabolome analyzed by ultra-high performance liquid chromatography (UHPLC) coupled to a hybrid quadrupole-time-of-flight mass spectrometer (QTOF-MS). The discriminating compounds were 94 at ST1 and 119 at ST2, and 35 of them were in common between the two sampling times. The majority of the discriminating metabolites (73 on 94 at ST1, and 109 on 119 at ST2) were found at higher concentration in the XS of S mng plants, compared to that of C mng ones. Most of the discriminating metabolites found in XS (about 80%, both at ST1 and ST2) were involved in plant secondary metabolism, mainly for plant chemical defense, growth regulation and signal transduction. The most prevailing class of compounds included terpenoids, phytohormones, alkaloids, sterols/steroids, retinols/retinoids, tocopherols and carotenoids. For the first time, we have demonstrated that the XS of a tree crop significantly responds to a shift of soil management. Generally, the plants of the S mng plot showed an up-regulated secondary metabolism. The results of our study encourage the use of a set of sustainable agricultural practices in a productive orchard, in order to enhance plant physiological status, increase yield quantity/quality, safeguard the environment and ameliorate human health. • Olive plants were managed by a sustainable (S mng) or a conventional (C mng) system. • A metabolomic analysis (UHPLC/QTOF-MS) of extracted xylem sap was conducted. • Deep differences in xylem sap composition were observed between S mng and C mng. • The plants from the S mng showed an up-regulated secondary metabolism. • The xylem sap of olive trees responded to a shift of soil management. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A sustainable (S mng) and a conventional (C mng) olive orchard were compared. • Pedological, chemical, and microbiological analyses on soils were carried out. • S mng showed a higher soil C and N in the topsoil layers, and lower pH. • N-cycling bacteria were higher in S mng but bacterial diversity did not change. • A new sustainable approach for optimizing soil C and N cycling is proposed. Abstract Under Mediterranean type climates, a sustainable soil management aimed at increasing soil organic carbon and microbiological diversity is of key importance. The aim of this study was to characterize and compare soils from a mature Mediterranean olive (Olea europaea L.) orchard subjected to two different soil management systems (sustainable, S mng , and conventional, C mng) for 18 years. Composite soil samples were analyzed qualitatively (pedological determinations) and quantitatively (soil C, N and pH). Bacterial metabolic activity and diversity were evaluated spectrophometrically by the Biolog® assay, while 16S-based metagenomics analysis was used to analyse the abundance of N-cycling bacteria. From the general analysis of the data obtained by the study of soil profiles and litter, C and N dynamics, and the genetic and functional diversity of soil bacteria, it emerged that the S mng system caused an improvement in soil organic matter in the topsoil layers, compared to the C mng system, with consequent increases in the abundance of soil N-cycling bacteria but without affecting the indices related to total bacterial metabolic activity and diversity. The results obtained could promote the development of new approaches for optimizing soil carbon cycling, managing nutrient transport, and sustaining and improving olive yield and quality. [ABSTRACT FROM AUTHOR]

Abstract: In Marlborough, New Zealand, olives are becoming an important crop alongside grapes. However, despite olives being drought resistant, they are generally planted on the poorer free-draining soils. Also, with the strong increase in cropping area, the demand for irrigation water has increased dramatically. In this research, we investigate the impact of short-term water stress on plant physiological processes, crop yield and oil quality in Marlborough, New Zealand. For that purpose, during the dry summer of 2000–2001, two trees were kept without irrigation for 64 days while two neighbouring trees were irrigated following standard practice. The trees were measured for transpiration (E), leaf and stem water potential (Ψ L and Ψ S ), every other day, from dawn to dusk for three weeks from just before irrigation was started up again. All four trees were wired up for measuring stem sap flow (T) which was recorded hourly and a basic meteorological station provided weather data. Fruit and shoot development was measured weekly. It was found that under the short period of dry conditions with soil moisture (() dropping to <5%, olive trees kept functioning at a very low level with Ψ L and Ψ S reduced from −1 to <−4.0MPa (T) reduced from 20 to 5mm/h and (E) reduced from 1.5 to 1.0mmolm−2 s−1. Within 10 days of restarting irrigation all these parameters were back to pre-drought levels. Both fruit and shoot growth came to a standstill within a week after drought was induced. During the first few days after re-watering, a high variability in Ψ L was found between leaves from the same trees. This variability disappeared after ∼six days. Shoot growth did not recover after re-watering but fruit growth rate, became the same as for continuously irrigated trees within days, but fruit size did not manage to recover before harvest. Yield from the dry trees was low because berry and pit weight were reduced by almost 50% at harvest, had a lower oil and percentage and were lower in phenolics. Stem sap flow was found to give a very good continuous measurement for the hydration status of the olive trees. [Copyright &y& Elsevier]