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Water shortage is one of the issues people are facing globally nowadays especially in arid and semi-arid regions. In these regions the increase in air temperature with slightly changing rates of precipitation cause frequent droughts. This determines the necessity for the usage of irrigation in agriculture that, in turn, makes it the most water consuming sector of economy.The detection of water stress using different approaches is crucial for irrigation scheduling and precise calculation of the volume of water that covers the gap needed for plants’ normal development.It is known that the Photochemical Reflectance Index (PRI) is highly sensitive to the photosynthetic activity of plants. Especially that can be observed for forests and orchards due to the high heterogeneity of canopy structure. In previous studies it was found that PRI can be used as an indicator for monitoring water stress in plants. However, at present, no full answer is given about the limitations of PRI usability and no clear algorithm is formulated for its use in order to detect water stress of plants.In this regard, we concentrate on studying the response of PRI to the water stress of olive trees rain-fed conditions for the case of semi-arid climate (Tunisia). We performed the analysis of data sets for 2021 and 2022, which are, respectively, a dry year and a year of normal water availability. The data sets included meteorological data, PRI measurements made every five minutes, sap flow measurements, soil moisture content values, and dendrometer measurements.On the first stage of our study we processed PRI data sets in order to find an analytic function that best describes daily dynamics of the index. As the result, a new modeling function is constructed to describe an increase in PRI in the middle of the day when minimal PRI values are reached several hours after sunrise and before sunset. Such PRI behavior was mainly observed in sunny days of the dry year.Further, we looked for the correlations of the characteristics of PRI daily dynamics, particularly minimal of PRI, with the values of sap flow that is a main measurable indicator in the class of transpiration and water stress models (see, e.g., https://doi.org/10.1016/j.agwat.2020.106343 ). In this context, the behavior of PRI was different for 2021 and 2022, which, in our opinion, related with weather conditions. For the dry year of 2021 we found a strong correlation between the minimum of PRI and sap flow in morning hours (R2= 0,68) during the summer season. For the normal year 2022 the same results are not obvious.In the perspective of our study it is planned to compare the results for the rain-fed site with the measurements obtained under irrigated conditions. The final goal of the research we want to achieve is to propose a reliable approach for separation of physically meaningful part of PRI signal from the noises created by the canopy structure. This will lead us to the reliable algorithm of PRI usage for the detection of plants’ water stress condition.

The effect of water deficit on photochemical parameters, hydraulic properties, phytochemical composition and radical scavenging activity were studied on four Olea europaea cultivars (Chetoui, Ouesl...

Hydrogels have a large interest for commercial application in agriculture. Our experiment was performed under greenhouse conditions, to examine the effect of the hydrogel “stockosorb-660” (TS) compared with non treated plants (TC). As compared to TC treatment, the hydrogel treatment increased clearly the growth responses, photosynthetic pigments, the dry weights and the relative water content of olive plantlets mainly in chemlali cv and under drought stress. Under drought stress, the chlorophyll fluorescence measurements were about 0.53 and 0.36 for chemlali and chetoui cultivars, respectively using TS treatment. In the same treatment, as compared to control plantlets, total phenols decreased damages under drought stress and were about 53.94 mg g−1 GAE and 57.37 mg g−1 GAE for chemlali and chetoui cultivars, respectively. Our results confirm also that “stockosorb” hydrogel is a cultivar dependent and seems to be probably suitable for agricultural use because of its capacity to avoid dehydration damages of young olive plants.

Predicting photosynthetic production in olive trees is a key feature in managing the effect of climate change on arid areas. Functional-structural plant modelling is a promising tool for achieving this goal. We used a photosynthetic sub-model that accounted for water and temperature stress and implemented it into LIGNUM model. We then conducted an experiment to validate the model at the leaf level using olive trees (Olea europaea) grown under various climatic condition. Then, we simulated photosynthetic production of three static olive tree models aged 1, 2, and 3 years. Results revealed a good fit between observed and predicted photosynthesis, with coefficient of determination (R2) values of 0.94 and 0.93 for Chemlali and Zarrazi cultivars, respectively. These results showed that the impact of water stress on photosynthetic production was marginal.

Arbuscular Mycorrhizal Fungi (AMFs) are known as a symbiotic microorganism which ameliorates growth and tolerance against stressful conditions of their host plants. It is characterized by morphological, physiological and biochemical events that are controlled by the interaction of both plants and fungus. The aim of this research was to evaluate the intensity (M%) and the Arbuscules abundance (A%) of mycorrhizal infection with Glomus intraradices in olive (Olea europaea L.) tree roots of five Tunisian local cultivars (cvs Oueslati, Meski, Jarboui, Chemlali and Chetoui). After 2 weeks of acclimatization in a greenhouse, the olive plantlets were inoculated with “G. intraradices”. The estimate of percentage of root colonization was calculated using an adequate method. This method consists of putting fragments of colored roots from each cultivar and observing them in a light microscope. These fragments were noted in a grid based on a scale class. Differences obtained in values were detected in all cultivars. This paper suggests the presence of cultivar-dependent differences in both the M% and A% that can be modified by AM fungi as well as by its interaction with olive roots. Results confirm also that oueslati cv has the best compatibility with G. intraradices. These findings open up many opportunities for mycorrhiza inoculation in the oleaster plants production in Tunisia. Key words: Olea europaea L., Glomus intraradices, arbuscules, Oueslati cv.

The impact of intercropping with two different forage crops (legume and grass) on the shoot growth, ion accumulation and some physiological traits of 3-old year olive trees irrigated by high-salinity water (120 mM NaCl) was assessed under greenhouse conditions. Olive plants were subjected to one of the following treatments: TC (control); TG – olive plants intercropped with grass (Oats: Avena sativa L) and TL – olive trees intercropped with legume (Berseem Clover: Trifolium alexandrinum L). Results showed that sodium root:leaf ratio and nitrogen concentration in olive leaves were significantly increased in TL treatment. Olive shoot length and maximum quantum yield of photosystem II (Fv/Fm) were significantly improved by using Berseem Clover as a cover crop. Negative correlation was observed between the total chlorophyll content and the leaf Na+ concentration. On the other hand, polyphenol content was significantly increased in olive leaves when oats were used as cover crops, in relation to the high N-deficiency observed in olive leaves of TG treatment.

The effects of soil amendment with the hydrophilic polymer Stockosorb ® on the physical properties of the soil as well as on physiological parameters (turgor pressure, stomatal conductance, chlorophyll fluorescence) and yield (vegetative growth, fruit characteristics, oil yield and quality) of an established olive crop cultivated under rainfed conditions, were investigated in Tunisia during the 2014 growing season. Stockosorb ® hydrogel was applied by injection in the soil around olive trees (TS) and compared to a control plot (TC) without hydrogel application. The results showed that water content was generally higher in hydrogel amended soils compared to the control soil. The seasonal leaf patch output pressure ( P p ) readings revealed that trees with Stockosorb ® treatment had the highest water status and were moderately stressed in comparison to control trees which were severely stressed due to the poor water status during the vegetative growth and fruiting period. The application of Stockosorb ® in the root zone of olive trees significantly increased midday stomatal conductance ( g s ) and the maximal quantum efficiency (Fv/Fm). Shoot growth, oil yield and rainwater use efficiency were strongly improved by the Stockosorb ® amendment to the soil, however oil quality still within the threshold limits set for an ‘Extra virgin' classified olive oil.

Aim: Despite its therapeutic value almost nothing is known about potential adverse health effects of Olea europea L. We therefore investigated the in vitro toxicity and genotoxicity of leaf extracts of this plant. Material and Methods: Extracts from olive tree leaves were obtained from four different regions in Tunisia. We investigated the in vitro toxicity, genotoxicity and antigenotoxicity of their aqueous extracts using the neutral red (NR) uptake, Vitotox and alkaline comet assays. Results: None of the extracts were found to be toxic and none of them were genotoxic, although some doubt exists for the extract obtained at Meski (North of Tunisia). On the basis of the Vitotox test only, none of the extracts appeared to have antigenotoxic (or cogenotoxic) properties. Discussion: The negative genotoxicity underline the safe use of the leaves, for example, as hypoglycemic and antidiabetic preparations. Lack of antigenotoxicity may indicate that the previously reported anticancer effects do not result from protection against genotoxicity. HIGHLIGHTS We investigated the in vitro toxicity and genotoxicity of aqueous extracts of olivesThe neutral Red Uptake test, Vitotox and alkaline comet assay were usedLeaf extracts from 4 different origins were investigatedNone of them showed in vitro toxicity or genotoxicityThe extracts also didn’t have antigenotoxic properties Abbreviation list: BaP: benzo(α)pyrene, EMS: ethyl methane sulfonate, LMP: low melting point, NI50: 50% inhibition of NRU, NR: neutral red, NRU: neutral red uptake, OD: optical density, PBS: phosphate buffer saline, SDS: sodium dodecyl sulphate, S/N: signal to noise ratio, 4NQO: 4-nitroquinoline oxide

Plant water relations and their dependence on microclimate and soil moisture were studied during 45 days in young olive trees cvs Chemlali and Chetoui subjected to a drying period and rehydration. The recently developed leaf patch clamp pressure (LPCP) probe were used for monitoring turgor-dependent leaf patch pressures ( P p) and compared with some conventional methods to detect water stress. Results show that, in well-watered olive plants, diurnal Pp is highly linearly correlated with vapour pressure deficit (VPD). Pp night readings gradually increased with increasing soil drought and revealed the beginning of water stress. At the end of the drying period, when the soil water content reach values less than the wilting point, only Pp curves detect the water stress in the two olive cultivars before the others methods tested here (ex: relative water content, chlorophyll content, chlorophyll fluorescence and stomatal conductance). Non-destructive, continuous leaf turgor pressure method showed promising potential for monitoring and detecting early water stress of young olive tree, in spite of sensibility to water stress, technological and data interpretation challenges requiring further attention.

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.

Olea europaea L. is one of the most important fruit trees in Tunisia because of its content of many potentially bioactive compounds. The aim of this study was to evaluate the chemical composition, antibiofilm, antiradical and acethylcholinesterase inhibitory activities from four Tunisian cultivars of Olea europaea L., i.e. 'Chetoui', 'Meski', 'Oueslati' and 'Jarboui'. By means of standardized methods, total phenols were determined and some of them characterized by HPLC. The total phenols and flavonoids contents were found to be the highest in the leaves of Chetoui cultivar. The Chetoui cultivar exhibited an important antioxidant and anticholinesterasic activity and an important anti-biofilm activity against Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, Candida albicans, Enterococcus faecalis and Escherichia coli, with percentages of inhibition comprised between 83 and 93% at 2xMIC values. Olive leaves extracts could be used in the control of bacterial biofilms in food and food-related environments.

Compost, olive mill wastewater and legume cover crops combined with complementary irrigation by saline water were tested under field conditions during 2016 and 2017 cropping seasons (‘Off’ and ‘On’ years respectively), in an organic mature olive grove cv Chemlali, grown at a density of 100 trees. ha-1. The experiment was conducted with four agronomic practices (TC-no amendment; TP-olive trees amended with compost, TM-olive trees amended with olive mill wastewater and TL-olive trees intercropped with legumes) factorially combined with two irrigation treatments (NI: non-irrigated olive trees and IR: olive trees irrigated with saline water of 4 g.l-1). The complementary irrigation by a limited quantity of saline water (4 m3.tree-1 per season) applied during the fruit growth (May-September) increased significantly the soil water content (SWC) mainly in the plot amended with compost. In both irrigated and rain-fed plots, the soil electrical conductivity (SEC) increased significantly during the dry season mainly in the control and the plot amended with olive mill wastewater (OMWW). Under rain-fed conditions, leaf sodium contents decreased by about 30 and 50%, respectively in olive trees amended by compost and those intercropped with legumes. Complementary irrigation with saline water increased leaf sodium levels in all plots, mainly in trees amended with OMWW, by about 40% compared to those of OMWW plot grown under rain-fed conditions. The level of leaf nitrogen increased by the application of both soil organic amendments and irrigation, while leaf phosphorus level was only affected by irrigation salinity, except for trees intercropped with legumes. Shoot growth, oil yield and fruit pomological characteristics were significantly improved either by the soil organic amendments or by the complementary irrigation. Nevertheless, phenol contents in fruits and in olive oil were significantly affected by compost and irrigation with saline water. Intercropping olive trees with legumes enhanced phenol contents in fruits and olive oil.

Abiotic stresses present a real environmental problem in agriculture field. In our paper, we examine the significance of arbuscular mycorrhizal fungi (AMF) and soil amendment with water retaining superpolymers (hydrogel) on growth and physiology performance of olive plantlets. Our experiment was carried out in nursery conditions, to test the impact of hydrogel (TH) and mycorrhizal fungi (TM), used individually or combined (THM), and compare them with non inoculated plants (TC), to understand and reduce the water stress damage in olive plantlets (cv. Chemlali). We also evaluate interactions between hydrogel, mycorrhizal treatments and water regimes. Results of mycorrhization (M%) show that roots colonized by Rhizophagus irregularis of well-watered plants were about 40.87%. In combined treatment (THM), M% was about 32.14%. Compared to TC treatment, TM treatment enhances significantly the dry weights of the whole plant under the two water regimes. The TM treatment had the highest relative water content (66.50%) and Chl (a + b) (0.83 mg g− 1) in stressed conditions. We found also that under water stress, the maximal quantum efficiency of the photosystem II measurements in leaves were significantly improved by 50.70% in TH treatment compared to control. For phenolic contents, TH treatment decreased significantly total phenols by 50.10% compared to TC. Our study gives evidence that the use of AMF and the hydrogel separately or in combination may enhance the capacity to avoid drought damages of olive plantlets and improve olive performances.

We studied changes in morphology, sclerophylly, chlorophyll photosynthetic parameters and total phenol contents in leaves of three olive (Olea europaea L.) cultivars; Oueslati, Jarboui and Meski which grew under water deficit conditions. Our results showed significant differences in trichome and stomatal densities, area of the leaf and relative surface of stomatal pores. The photosynthetic parameters Fv/Fm, Phi PSII and ETR were negatively affected by the water deficit in these three varieties. The total phenolic and flavonoid contents increased in all cultivars, with Oueslati showing the highest values. The Oueslati variety could be considered as the most drought-tolerant compared to Jarboui and Meski. Therefore we believe this cultivar is the most suitable for cultivation in semi-arid environments. (c) 2018 SAAB. Published by Elsevier B.V. All rights reserved.

The experiment was carried out on olive trees cv. Chemlali, during two successive years (2013/2014). Two irrigation treatments (IT: Trees irrigated with wastewater; TRC: Trees grown under rainfed condition) were combined with two tillage practices (TTS: Trees grown in tilled soil; TNTS: Trees grown in non-tilled soil).; Results: The results of the study showed that wastewater irrigation combined with soil tillage improved the pomological characteristics of olive fruits. The tree yield increase was substantial for IT and TTS. However, most of the identified phenolic compounds, especially oleuropein, mainly accumulated in olive fruits of the TC block (TNTS + TRC), suggesting a marked improvement in the nutritional value of these fruits. Moreover, fruits of TNTS had high contents of sugar compounds, required for the synthesis of the fruit storage material. The study also showed that the agronomic practices affected the amounts of some aromatic compounds responsible for the distinctive flavour notes of olive oil.; Conclusion: Agronomic practices may affect considerably the commercial and nutritional values and the sensorial quality of the commodities. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

Ruscus hypophyllum L. is a rare Mediterranean plant which is used in the traditional medicine. We studied its phenolic content and in vitro toxicity and genotoxicity using the neutral red uptake (NRU) test, the bacterial Vitotox test, and the comet assay in human C3A hepatic cells. Aqueous leaf and fruit extracts were investigated. Antigenotoxicity against 4-nitroquinoline-oxide (4NQO, 0.4 mu g/mL) and Benzo(alpha) pyrene (BaP, 800 mu g/mL) was also investigated with the Vitotox test. The extracts appeared to be genotoxic only at high exposure levels in the comet assay. There was no indication of a genotoxic activity in the Vitotox test and also no indication of antigenotoxicity. The moderate polyphenol content may provide an explanation for the absence of antigenotoxicity.

The effects of salinity, on three olive tree cultivars (‘Picholine’, ‘Meski’ and ‘Ascolana’), growing under greenhouse conditions, were studied through the following parameters: vegetative growth, stomatal density and ion accumulation (Na + , K + , Ca 2 + , and Cl − ). Olive plants were subjected to three saline irrigation treatments: T0 (irrigated with tap water), T1 and T2 irrigated with 6 and 9 g of NaCl·l 1 solution respectively. As salinity increased, vegetative growth, stomatal density, root dry weight and root density of ‘Meski’ and ‘Ascolana’ declined sharply. Sodium accumulation was greater in leaves and roots with increased external NaCl concentration, but differently according to cultivars. In fact, Na + concentration was higher in leaves than in roots for ‘Meski’ and ‘Ascolana’ cultivars. However, for ‘Picholine’ the highest content of Na + was in roots. Generally, ‘Picholine’ accumulate less Na + in leaves and were able to maintain higher K + /Na + ratios compared to other cultivars. In leaves, ratios of K + /Na + and Ca 2 + /Na + between cultivars were lower in salinity treatments compared to control. ‘Meski’ and ‘Ascolana’ have a higher power of water desalination than ‘Picholine’.

The present work was aimed at evaluating, under natural situations (field of olive trees, Olea europea cv Chemlali), the effects of one-year agronomic application of an olive mill wastewater (OMW) biologically derived compost. The experimental study was carried in 2014 in an olive orchard situated at Jammel (region of Monastir-Tunisia). An experimental plot (TM, 50 olive trees) was amended on February 2014 (the 'Off year) with 50 m 3 /ha. The plot TC (50 olive trees) was not amended and served as a control. After one year of OMW application, at harvest, olive fruits were collected and pomological characteristics were determined. Olive oil was extracted and biochemical parameters were studied. Statistical analyses showed that short-term field application of OMW affected negatively carpometric characteristics of olive fruits and oil content. Oil produced from TM had a decreased pigment content and oxidative stability. Moreover, the level of MUFA, particularly oleic acid, as well as C18:1/C18:2 and MUFA/PUFA ratios were negatively influenced by OMW amendment which affects negatively olive oil quality and nutritional value. These findings must be taken into consideration when developing strategies for oil quality enhancement, especially in an exporting country like Tunisia.

Chlorophyll content, fluorescence parameters, xylem hydraulic properties, total phenolic content and antiradical activity were studied on young plants of four Tunisian olive cultivars (Chetoui, Ouslati, Jarboui and Meski) grown under water deficit conditions for two months. Water stress caused a decline in chlorophyll content, in maximum quantum yield of photosystem II (Fv/Fm), in linear electron transport rate (ETR) and in quantum efficiency of PSII electron transport (Φ PSI). Chetoui variety was the less affected by water stress but all these parameters decreases considerably in Ouslati, Jarboui and Meski. In all cultivars, water stress induced an increase in xylem vessel frequency. Water stress also increased the phenolic and flavonoid contents and antiradical activity in all cultivars. Chetoui cultivar may be considered as the most tolerant cultivars among the tested cultivars showing higher phenolic and flavonoid contents and an important antiradical activity under water deficit. Meski cultivar is the most sensitive one.

We evaluated the potential of sap flow values estimated from records with the heat dissipation method for irrigation in an olive orchard (Olea europaea L, cv. Meski) near Enfidha, Tunisia. Trees were cultivated at 7 × 7 m spacing. Two drip irrigation treatments were imposed using the sap flow and the FAO methods. The two treatments were irrigated by 100% of crop evaptranspiration (ETc). T1: ETc measured by the sap flow method and T2: ETc estimated by the FAO method. Sap flow, leaf and stem water potentials, leaf photosynthetic activity, stomatal conductance and transpiration rate were recorded in representative trees from both treatments, during the full irrigation season from April to August. Results showed that the irrigation dose calculated from T2, based on FAO method compared to the T1, based on sap flow decreased by about 25%. Under T1 irrigation scheduling strategy, the daily transpiration decreased by 20% and consequently the water potentials were decreased significantly. Infect, olive trees under T1 were moderately stressed and subsequently leaf gas exchange parameters were affected by about 15%. Key words: Sap flow, water potential, leaf photosynthetic activity, olive tree, Olea europaea irrigation scheduling.

Most of the studies investigated the effects of nutrient-based fertilizers on olive fruits and oil quality; few studies have been interested in the modification of the chemical composition of olive leaves in response to fertilization. Thus, the current study aims to examine the effects of foliar fertilization on the mineral profile of olive leaves as well as the concentrations of chlorophyll, antioxidants (phenolic compounds) and carbohydrates. Experimentation consists of the annual application of six treatments during two successive growing seasons (2009–2010): TC (untreated trees), P1 (nitrogen-based fertilizer), P2 (contains boron, magnesium and manganese), P3 (phosphorus and potassium based fertilizer), P4 (rich in calcium and phosphorus), T5 (P1 and P2 application) and T6 (P1, P2, P3 and P4 application). At the end of the experiment, mineral analysis of olive leaves showed an increase in the concentrations of most nutrients which induced changes in biochemical composition: an increase of chlorophyll content, a reduction of total phenols and oleuropein concentrations coupled with an increase of hydroxytyrosol level. Moreover, an increase of total sugar content and most individual sugars, principally translocated forms of sugars (mannitol, sucrose and raffinose), was also observed. The accumulation of these key physiological parameters by foliar fertilization suggests an improvement of physiological performance and photosynthetic capacity of olive trees. Moreover, from a biological point of view, the results of the study revealed the possibility to improve plants of medicinal interest by enhancing the accumulation of some bio-active compounds, such as hydroxytyrosol and mannitol, via foliar nutrient supply.

Since antiquity, the Meskat system was adopted practice to sustain olive tree cultivation in the Tunisian Sahel region. This technique was based on the runoff harvesting from catchment area to irrigate downstream plots planted with olive trees as blocks. This paper aims to study the spatial distribution and characterization of Meskat system. A set of maps and satellite data were used and integrated into a geographic information system to perform the inventory of the Meskat system used in Sousse region. The sizing of this system was based on the estimation of the ratio between a catchment area (impluvium) and the cropped area of each entity, called “K ratio”. The results showed that Meskat system is implemented in five watersheds in Sousse region; especially Wadi Hamdoun watershed is the most fitted. Meskats are installed, mostly, on soils characterized by medium to fine textures, poorly suitable for infiltration. The K ratios vary from 0.04 to 6.62 with 0.76 as average. For all Meskat system 87% had K ratio less than 1.5 which is the ideal ratio for optimum olive production, indicating that the system seems to be undersized.

Here, we report the characterization of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivar (Chemlali) grown in four planting densities (156, 100, 69, and 51 trees ha(-1)). Olive oil samples obtained from fruits of trees grown at 100 trees ha(-1) had a higher content of oleic acid (65.5%), a higher content of chlorophyll and carotenoids, and a higher content in total phenols (1059.08 mg/kg). Interestingly, olives grown at the two highest planting densities yielded more stable oils than olives grown at the two lowest ones. Thus planting density is found to be a key factor for the quality of olive oils in arid regions.

The olive oil content in phenolic compounds depends on the variety of the fruit used for its extraction as well as on the predominant climate conditions in the tree cultivation area. Here, we report on the characterization of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivars Chemlali and Chetoui, grown in three different Tunisian locations, Zaghouan (North), Sousse (Center) and Sfax (South). Chetoui olive oil samples obtained from fruits of olive trees cultivated in Zaghouan and Chemlali olive oil samples obtained from fruits of olive trees cultivated in Sousse were found to have a higher mean total phenol content (1004 and 330 mg/kg, respectively). Olive oil samples obtained from fruits of both cultivars had different phenolic profiles and a higher content in 3,4-DHPEA-EDA when the olive trees were cultivated in Zaghouan. Both olive cultivars were found to have different responses to environmental conditions. Chetoui olive oil showed decreased oxidative stability when the fruits were obtained from olive trees cultivated in the center of Tunisia (34.8 h) and in Sfax (16.17 h). Furthermore, statistical data showed that the phenolic composition and oxidative stability of Chetoui olive oil varied more by location than those of Chemlali olive oils.

Differences in abscisic acid (ABA) accumulation between two olive cultivars were studied by enzyme-linked immunosorbent assay in roots and leaves, leaf water potential (Ψl), stomatal conductance (g s) as well as photosynthetic rate (A) were also determined in well-watered (WW) and water-stressed (WS) plants of two olive cultivars ‘Chemlali’ and ‘Chetoui’. ‘Chemlali’ was able to maintain higher leaf CO2 assimilation rate and leaf stomatal conductance throughout the drought cycle when compared with ‘Chetoui’. Furthermore, leaf water potential of ‘Chemlali’ decreased in lower extent than in Chetoui in response to water deficit. Interestingly, significant differences in water-stress-induced ABA accumulation were observed between the two olive cultivars and reflect the degree of stress experienced. Chemlali, a drought tolerant cultivar, accumulated lower levels of ABA in their leaves to regulate stomatal control in response to water stress compared to the drought sensitive olive cultivar ‘Chetoui’ which accumulated ABA in large amount.

Leaf structural adaptations for the reduction of water loss were examined in two olive (Olea europaea L.) cultivars (Chemlali and Chetoui) growing under water stress conditions. Leaf measurements included leaf tissue thickness, stomatal density, trichome density, specific leaf area, leaf density, water relations, and gas exchange. We found considerable genotypic differences between the two cultivars. Chemlali exhibited more tolerance to water stress, with a thicker palisade parenchyma, and a higher stomatal and trichome density. Chemlali leaves also revealed lower specific leaf area and had higher density of foliar tissue and lower reduction in net CO2 assimilation rate. The mechanisms employed by these two cultivars to cope with water deficit are discussed at the morpho-structural level. The morphological and structural characteristics of the leaves are in accordance with physiological observations and contribute to the interpretation of why the olive cv. Chemlali is more drought-tolerant than cv. Chetoui. Furthermore, from the behaviour of Chemlali plants we consider this cultivar very promising for cultivation in semi-arid areas.

This research, aimed at evaluating stress on the olive tree, utilized cultivars ‘Meski’ and ‘Chetoui’ in regards to the removal of major elements such as nitrogen (N), phosphorus (P), magnesium (Mg...

The comparative responses of two young olive trees (Olea europaea L. ‘Chemlali’ and ‘Chetoui’) to drought stress were investigated during 1 month. Three-month-old own-rooted plants were subjected to two irrigation treatments: WW (well watered plants that were irrigated with fresh water to maintain a soil water content close to field capacity), and WS (water stressed plants by withholding water). Leaf water potential, gas exchange and leaf lipid composition were studied. ‘Chemlali’ was able to maintain higher leaf CO2 assimilation rate and leaf stomatal conductance throughout the drought cycle compared to ‘Chetoui’. Water stress induced a larger decrease in the total lipid content in ‘Chetoui’ than in ‘Chemlali’. Interestingly, the constitution of different lipid classes was highly altered in ‘Chetoui’. Lipid changes in Chemlali, a drought tolerant cultivar, revealed more stability of its cellular membranes to drought stress as compared to the drought susceptible olive cultivar, Chetoui. Furthermore, in comparison to the controls, drought stressed plants showed an increase in the degree of unsaturation of leaf lipids in the two olive cultivars. Moreover, the results observed in Chemlali showed that besides changes in lipids composition this cultivar may have an efficient defence strategy which can be related on antioxidative production against oxidative stress.

The aim of this study was to evaluate the quality of two European olive cultivars , ‘Koroneiki’ and ‘Arbequina’, introduced in South and North of Tunisia. Olives grown in the two locations yielded extra virgin olive oils. Northern olive oils showed a greater amount of oleic acid, phenols and a higher stability, whilst in the southern oils had higher saturated and linoleic acid content. Phenolic compounds were also influenced by the pedoclimatic conditions; hence, oils from the North had the highest level of 3,4-DHPEA-EDA and a higher content in oleuropein aglycon (3,4-DHPEA-EA) than the corresponding olive oil samples obtained from trees cultivated in South. Furthermore, the majority of the studied analytical parameters were greatly influenced by the cultivar‐environment interaction. In fact, significant differences between the studied oils were detected.

The present study focused on the comparison the chemical composition of virgin olive oil samples obtained from fruits of the main Tunisian olive cultivar (Chemlali) grown in four planting densities (156, 100, 69, and 51 trees ha−1). Despite the variability in the triacylglycerols and volatile compounds composition, the quality indices (free fatty acids, peroxide value, and spectrophotometric indices K232and K270) all of the virgin olive oils samples studied met the commercial standards. Decanal was the major constituent, accounting for about 30% of the whole volatiles. Moreover, the chemical composition of the volatile fraction of the oil from fruits of trees grown at the planting density of 156, 100, and 51 trees ha−1was also characterised by the preeminence of 1-hexanol, while oils from fruits of trees grown at the planting density of 69 trees ha−1had higher content of (E)-2-hexenal (20.3%). Our results confirm that planting density is a crucial parameter that may influence the quality of olive oils.

The objective of this work was to assess the pollen viability, the pollen capacity (germination and tube growth) and the rate of fruit set in 19 cultivars of olive trees field-grown in Chott Mariem (Tunisia) after self-and free-pollination treatments during two seasons 2012 ('on'year) and 2013 ('off ’year). The pollen viability ranged from 60.5% for ‘Meski ’to 88.85% for ‘Gerboui ’during 2012 ('on'year) and between 97.47% for ‘Chetoui ’to 62.38% for ‘Meski ’in 2013 ('off ’year). All the cultivars increased their values of viability and germination during 2013 comparatively to 2012, with important consequences on the fertilization process measured by the initial fruit set rate. Concerning the pollination treatments, generally, the free-pollination improved fruit set when compared with self-pollination, especially for ‘Meski ’. However, a non-pollination of ‘Ascolana ’and ‘Tounsi ’was observed with all pollination modes and during the two years in Chott Mariem. Our results showed a high correlation between the rate of fruit set after self-and free-pollinations during the two years of study 2012 and 2013 (respectively, r2= 0.74 and 0.65). This study highlights some major remarkable differences among cultivars in terms of pollen abilities. In general, concerning the pollination efficiency of olive cultivars, the pollen viability can be an important characteristic to be considered as an indicative parameter of pollen development and functionality. Finally, this is a topic of particular importance for large-scale isolated plantings and in choosing the cultivars in new olive groves plantations.