The Mediterranean region's agriculture is predicted to be severely impacted negatively by climate change. In the primary production region of southern Tunisia (34°43’N, 10°41’E) in olive orchard submitted to different treatments: Rain-fed, drip irrigation with saline water (FI) : EC = 7.5 dS/m at 100% of crop evapotranspiration (ETc), alternate irrigation (PRD) with saline water at 50% of ETc and switched every 30 days, regular deficit irrigation (RDI) with saline water at 50% of ETc, drip irrigation with tap water (TW) : EC=2.46 dS/m at 100% of crop evapotranspiration (ETc), with predicted temperature increases, the effects of climate change and salinity on the floral performance of olive trees were assessed from 2015 to 2017 and the vegetative growth and yield were evaluated over the period. As results, while conserving water in comparison to FI and TW, PRD produced high values for internodes length (1.68 cm) in 2016 and an annual shoot elongation (2.5 cm) in 2015. When comparing flowering (RF) and fruit-setting (RS) rates, olive trees under PRD outperformed those under RDI and FI with (RF=67.52% and RS=7.81%) in 2015. For olive trees exposed to RDI, PRD, and FI, the fruits per unit length were statistically similar in 2015. The use of the PRD technique (50% ETc) yielded good results with an average of 2.96(kg/m3) in our study both quantitatively and qualitatively.

In olive-growing regions, climate change exacerbates challenges like high temperatures and water scarcity, necessitating a deeper understanding of its impact on olive trees behaviour to cope with drought. This study assesses the ecophysiological performance of 12-year-old olive trees ‘Chemlali Sfax’ (local) and ‘Koroneiki’ (Greek) and drought response mechanisms for developing agronomic strategies that ensure sustainable yields despite adverse climatic conditions in the Mediterranean region (Tunisia). Leaf water content declined from February, with ‘Chemlali Sfax’ and ‘Koroneiki’ maintaining higher content (59

The evaluation of salt-tolerant olive tree genotypes released from breeding program has become intrinsic in order to develop sustainable agriculture in these regions. The current study aims to i) evaluate the tolerance of two new released olive cultivars (Zeitoun Ennour and Zeitoun Ennwader), issued from a Tunisian breeding program in comparison with the main olive cultivar ‘Chemlali Sfax’, and ii) identify suitable salt-tolerance indicators for this evaluation. The trial was conducted under controlled conditions in a greenhouse, for six months, and plants were irrigated with half-strength Hoagland nutrient solution containing NaCl at various levels (0, 75, 150 and 225 mM). Vegetative growth, biomass allocation and biochemical parameters were considered for the assessment of salt-tolerant capacity. Results revealed that growth and biomass should be considered as useful indicators for early evaluation method of salt-stress tolerance. ‘Chemlali Sfax’ displayed a gradual significant decrease of vegetative growth with increasing salinity. The reduction of shoot elongation and trunk diameter was most evidently at 150 mM with 43.2 % and 80.8 %, respectively. However, the new released cultivars showed unaffected vegetative growth, despite a slight decrease at the salt level of 225 mM. Moreover, results demonstrated the importance of certain physiological and biochemical indicators such as ions contents. The new released cultivars maintained a high K+/Na+ ratio at moderate salinity then a significant decrease occurred at 150 mM. In conclusion, vegetative growth, biomass allocation and K+/Na+ ratio seemed to be the suitable salt-tolerance indicators for early evaluation. Based on these indicators, ‘Zeitoun Ennour’ seems to be the most salt tolerant genotype and ‘Zeitoun Ennwader’ proves to have a similar salt tolerant capacity as ‘Chemlali Sfax’, which is a valuable information for olive growers in arid region.

In order to utilize arid lands, an olive varietal orchard was established in 2000 in the arid region of Boughrara (Sfax, Tunisia) under rainfed conditions. The orchard contained the local variety Chemlali Sfax and Greek one, Koroneiki at a density of 34 trees/ha (17 m x17m). The study looked at the production for six years (2008 to 2014) and evaluated the productive performance of olive trees over the period. The performance of the two cultivars showed that they were potentially promising under rainfed conditions around an average of six years (1188.54 kg/ha) since they demonstrated a strong flowering rate (41.71-61.47%), a low ovary abortion of the flowers (0.95-16.82%) and an inflorescence quite furnished with flowers (13/inflorescence -21/inflorescence). The agronomic parameters bring out common points between the two cultivars. Indeed, a high production of olives is intricately linked with a strong flowering, an abundance of inflorescences with a reduced number of flowers. These characteristics of flowering in year "on" or year of production indicated a specific strategy to establish an internal balance to cope with rainfed conditions in arid climate. Thus, in the event of strong flowering, Chemlali Sfax and Koroneiki reacted similarly by the reduction of the flowers per inflorescences. The only difference was the fruit set rate which was higher in Chemlali Sfax. In addition, the two varieties ensured high production by increasing the rate of inflorescence and decreasing the rate of ovary abortion. It could be deduced at this level that the good productive performance under the arid climate was due to mobilizing small inflorescences and the reduction of ovary abortion.(c) 2023 Published by Elsevier B.V. on behalf of SAAB.

The olive tree, an iconic symbol of the Mediterranean basin, is the object of growing international interest in the production of olive oil for the world food market. In Tunisia, which is the fourth-largest producer of olive oil in the world, the production of olives and olive oil is of great socio-economic importance. Cultivation is widespread from north to south, but it is carried out using traditional techniques that results in extremely irregular production levels. To maintain their competitiveness on the international market, Tunisian producers must improve the quality of the oil through breeding plans that enhance the rich genetic heritage that is still not adequately exploited. The objective of this review is to present the state of olive breeding in Tunisia, illustrating the opportunities available for a better use of the rich Tunisian genetic heritage, the challenges it must face, and the need to multiply the efforts for sustainability, even in the light of the challenges posed by climate changes.

Cinq hybrides d’olivier issus de la variété tunisienne ‘Chemlali Sfax’ ont été obtenus à partir de croisements dirigés pour améliorer la composition acidique de l'huile. L’objectif de ce travail est d’étudier le comportement agronomique de ces hybrides dans un verger conduit en irrigué (Sfax, Tunisie). L’étude de la composition acidique révèle que 4 hybrides se caractérisent par un taux en acide oléique supérieur à 69 % et un taux en acide palmitique inférieur à 16 %. L’étude des paramètres agronomiques montrent que les hybrides ont de bonnes performances au niveau d’un caractère déterminé. Deux hybrides ont un poids du fruit > 2 g, un hybride avec productivité et vigueur élevées, respectivement de 37,4 kg/arbre et 10,6 m3, et un hybride avec une vigueur réduite. De ce fait, 4 hybrides peuvent être proposés à l’inscription pour une culture irriguée et intensive et un hybride est à exclure de l’inscription vu sa composition acidique de l’huile similaire à la variété locale de référence ‘Chemlali Sfax’. Mots-clés: Olivier, hybrides, Paramètres agronomiques, Composition en acides gras

Article History Received: 22 January 2021 Revised: 2 March 2021 Accepted: 30 March 2021 Published: 26 April 2021

The reuse of treated wastewater for olive irrigation is becoming a common practice in areas with limited water resources. However, this water may contain high level of salts (Na+ and Cl−) that could affect plant performances when used for a long period. In order to enhance the tolerance of plants to salt stress induced by treated wastewater, the application of arbuscular mycorrhizal fungi (AMF) may be a suitable solution. In this study, the ability of different AMF inoculums to improve young olive plants (Olea europaea L. cv. Chetoui) performances under long term irrigation with treated wastewater was studied. One-year-old olive trees inoculated with Glomus deserticola and/or Gigaspora margarita were irrigated with treated wastewater for one year. As compared to plants irrigated with tap water, treated wastewater irrigation caused a significant decrease in relative water content (RWC), total fresh and dry weights, gas exchange parameters, and chlorophyll and starch contents. Nevertheless, a significant increase in Na+ and Cl−, proline, soluble sugars, total polyphenols as well as flavonoids contents was observed under treated wastewater irrigation. Interestingly, colonization with different AMF inoculums, particularly the 1:1 mixture of G. deserticola and G. margarita, alleviated the negative effect of saline treated wastewater on young olive plants and significantly improved the above parameters. In fact, mycorrhizal symbiosis decreased the Na+ and Cl− contents and improved the RWC, the total fresh and dry weights and the photosynthetic activity. Furthermore, mycorrhizal plants showed higher concentrations of proline and soluble sugars as well as higher antioxidant defense systems as compared to the non-inoculated plants.

The modeling of a parallel ferroresonant circuit leads to a single-phase model formed of many elements, which of course translates into a large number of state variables, and therefore of high dimension. We show how it is possible to gradually reduce the adopted model dimension while retaining certain characteristic quantities which seemed important for the ferroresonance study; and validate the different approximations made. Different results temporal and frequency obtained numerically on the developed models (simulating parallel ferroresonance real cases), are presented and commented. We confirm that the parallel ferroresonance is sufficiently represented qualitatively by a reduced model of dimension three. © 2019 Elixir All rights reserved. Elixir Elec. Engg. 136 (2019) 55043-55051 Electrical Engineering Available online at www.elixirpublishers.com (Elixir International Journal) Fathi Ben Amar/ Elixir Elec. Engg. 136 (2019) 55043-55051 55044 established in anterior works [2-4, 12-15]. Indeed, by this study, we seek to accuse the validity of these models and highlight the network parameters that seem interesting to us to represent the situations of parallel ferroresonance appearance. The purpose of this modeling is to represent the network by a system of nonlinear ordinary differential equations, nonautonomous system, parameterized, of the form:    , , t X F dt dX  (1)   n X i X X    , is the solution vector of the system whose components are the state variables (flux, voltages and currents) appearing on the network; the size of this vector depends on the modeling finesse, p    is the vector containing the network parameters (line length, impedances, resistances, supply voltage, etc.), F is a function explicitly dependent on time, because of the presence of the periodic forcing term, in sinusoidal function form. The transformers’ presence, whose characteristics are not linear, makes F non-linear with respect to its variables i X ; which explains the appearance of unexpected phenomena on the network. As the transient simulation times of the phenomenon are important and tedious, we have already developed in [17] a direct calculation code of the steady state without going through the calculation of the transient state by using the bifurcations theory [4-7, 17]. This computation code is based on the frequency method of Galerkine [5-7, 9, 17] and the pseudo-arclength continuation method [5-7, 17]. Both methods are satisfactory. They allow us to easily construct the bifurcation diagrams and obtain a global view of the phenomenon [4-7, 9-11, 17]. IV. Description of the voltage feedback configuration In voltage feedback situations, the operator is forced to send back a voltage (periodic versus time) to unloaded transformer located at the end of a long line. We distinguish, then, in this system three constituent elements (Figure 2): the voltage source (alternator and its step-up transformer), the energy transmission line, the target transformer and its non-linear current-flux characteristic. Figure 2. Example of a simplified configuration representing the voltage feedback from Chastang toward Chinon (France) [13]. As Blengino asserts [11], the real network is three-phase but the results are generally very close between phases [1114]. That's why we chose a single-phase representation of the system considering only the direct component. IV.1. System elements modeling For numerical simulations to provide reliable results, a good model must be used in computational programs. To achieve this goal, it is essential to adequately represent each component of this network. We propose here a modelization synthesis, which are also the subject of an abundant literature [9, 11-15]. IV.1.1. Voltage source model The voltage supplied to the network comes from a source composed of an alternator accompanied by a step-up transformer (unsaturated: its characteristic is linear) (figure 3). The whole is modeled by the following single-phase element: Figure 3. Voltage source model. This representation proved sufficient during studies of ferroresonance [11, 12]. The alternator is represented by a sinusoidal e.m.f.          t E t e sin located behind his subtransient reactance " d X increased by the leakage reactance of the source transformer t X : t d a X X X   " (2) To hold into account the internal damping of the alternator's e.m.f., we associate a subtransient time constant "  . This damping is represented by a series resistance a R calculated by the following relation:

Among the countries of the Mediterranean Basin, Tunisia is located at the crossroad for the immigration of several civilizations over the last two millennia, becoming a strategic place for gene flow, and a secondary center of diversity for olive species. Olive is one of the principal crop species in Tunisia and now it strongly characterizes the rural landscape of the country. In recent years, collecting missions on farm and in situ were carried out by various institutes, with special emphasis given to ex situ collections serving as a reference for the identification of olive germplasm. Simple Sequence Repeats (SSRs) represent the easiest and cheapest markers for olive genetic fingerprinting and have been the tool of choice for studying the genetic diversity of this crop in Tunisia, to resolve cases of homonymy and synonymy among the commercialized varieties, to identify rare cultivars, to improve knowledge about the genetic variability of this crop, to identify a hot spot of olive biodiversity in the Tunisian oasis of Degache, and to enrich the national reference collection of olive varieties. The present review describes the state of the art of the genetic characterization of the Tunisian olive germplasm and illustrate the progress obtained through the SSR markers, in individuating interesting genotypes that could be used for facing incoming problems determined by climate changes.

An olive breeding program was started in Tunisia in 1993 in order mainly to improve the fatty acid composition of the local cultivar ‘Chemlali Sfax’. ‘Zeitoun Ennour’ is a new cultivar obtained from a cross between ‘Chemlali Sfax’ and the local dual-purpose use cultivar ‘Chemchali Gafsa’. The morphological study of this cultivar showed that eleven characters dealing with fruit and endocarp differed from ‘Chemlali Sfax’, mainly regarding to their respective weights. This new cultivar had the same sensitivity to Verticillium dahliae Kleb and earlier bearing than the original variety. Its olive production was considered as high as for ‘Chemlali Sfax’ but with partial self-compatibility and late maturity. The new cultivar realized a net improvement in comparison with the original cultivar particularly regarding its fatty acid composition with very high oleic acid content (>75 %) and low palmitic and linoleic acid contents (<10 %). The new cultivar was recently released and will be available for growers as soon as possible.

Olive is one of the oldest cultivated species in the Mediterranean Basin, including Tunisia, where it has a wide diversity, with more than 200 cultivars, of both wild and feral forms. Many minor cultivars are still present in marginal areas of Tunisia, where they are maintained by farmers in small local groves, but they are poorly characterized and evaluated. In order to recover this neglected germplasm, surveys were conducted in different areas, and 31 genotypes were collected, molecularly characterized with 12 nuclear microsatellite (simple sequence repeat (SSR)) markers, and compared with 26 reference cultivars present in the Tunisian National Olive collection. The analysis revealed an overall high genetic diversity of this olive’s germplasm, but also discovered the presence of synonymies and homonymies among the commercialized varieties. The structure analysis showed the presence of different gene pools in the analyzed germplasm. In particular, the marginal germplasm from Ras Jbal and Azmour is characterized by gene pools not present in commercial (Nurseries) varieties, pointing out the very narrow genetic base of the commercialized olive material in Tunisia, and the need to broaden it to avoid the risk of genetic erosion of this species in this country.

Summary A total of seventeen olive ecotypes were identified in the oasis region of Degache (Tozeur, Tunisia). The following physicochemical parameters of their oils were studied: acidity, refraction index, polyphenol, chlorophyll and carotene contents, oleic, palmitic and linoleic acid levels and the UV absorbance (K232 and K270). The acidity, K232 and K270 parameter values were used to classify most of the olive oils considered as ‘extra virgin’. The highest carotene, chlorophyll and polyphenol contents of the olive oils examined were found to be 13.60 ppm, 9.10 ppm and 796 ppm, respectively. The oleic acid level of the olive oils considered ranged between 47% and 73%, whereas the palimtic acid level ranged between 11.8% and 23%, and the linoleic acid level ranged between 8.8% and 22.5%. Therefore, the fatty acid composition of the most olive oils considered was in keeping with the IOC norms. The Pearson correlation coefficients obtained were found to be negatively significant for the oleic, palmitic and linoleic acid levels recorded. The cluster and principal component analyses performed revealed the importance of fatty acids and polyphenol contents in the clustering of olive ecotypes. The selection of olive ecotypes according to oil quality is possible, requiring further studies focusing especially on their agronomic characters.

Tunisia is one of the world’s largest producers of olive oil, and it preserves pools of olive genetic diversity that are still unexplored. A recent prospection and collection program of the National Gene Bank of Tunisia (NGBT) focused on the vast oasis of Degache, in the south west part of Tunisia, where 47 samples were collected and genetically characterized through simple sequence repeat (SSR) markers. Identification and authentication of genotypes were obtained through comparison with reference cultivars belonging to the Olive National Collection of Tunisia (IOC) and with cultivars from Algeria, Italia, Syria and Lebanon. Degache olive genotypes showed large genetic variability, a significant diversity from the reference germplasm, and a clear differentiation from modern varieties. The population structure analysis identified four gene pools characterizing genotypes from different area of origin. Two gene pools appear to be more represented in germplasm from southern Tunisia, where environmental conditions at critical plant development phases, are harsher. This suggests that this germplasm might present traits of adaptation useful for breeding to improve resilience to abiotic stresses. Our results will support ex situ and in situ conservation activities of Tunisian olive germplasm pursued by the National Gene Bank of Tunisia.

The incidence of fungal diseases affecting olive trees increased in Tunisia. Mycoflora isolated from diseased olive trees revealed their colonisation by several fungal species such asFusarium oxysporum,F. solani,F. lateritium,Macrophomina phaseolina,Rhizoctonia solani,Athelia rolfsii,Neonectria radicicola,Verticillium dahliae,Armillaria mellea,Phytophthora megasperma,P. palmivoraandPythiumsp. These fungi were also isolated from roots and collars of young olive cuttings in the nursery, where they caused severe losses. Most of the fungi were pathogenic and caused typical symptoms of dieback upon their inoculation on olive plants, which fullfill the Koch's postulate. These pathogenic fungi showed the ability to infect, either separately or jointly the olive tree. Moreover, cropping of olive in high clay soil and irrigation with high saline water increase the fungal incidence and plays a major role in the disease outbreak.

The most outstanding olive oil cultivar ‘Chemlali Sfax’ has low oleic acid level and high palmitic acid content and a tendency to biennial bearing. Cross breeding program of this cultivar was undertaken in Tunisia since 1994 using local and foreign cultivars. Selected hybrids were planted in a comparative trial since 2005. This study aim to characterize a new olive cultivar 'Zeitoun Ennwader' better than the original cultivar. Data on morphologic, agronomic and oil quality were recorded for the new cultivar. This cultivar is distinguishable from the original cultivar due to its morphological parameters of the fruit (shape, symmetry and apex) and the endocarp (symmetry, position of maximum transverse diameter and apex). This cultivar is different from the original variety on the agronomic plan by its low alternate bearing, its early bearing and its moderate sensitivity to verticillium. The oil of the new cultivar is different from the original variety by its better fatty acid composition (higher oleic acid content and lower palmitic acid content). The adoption of this cultivar will be of great benefit to farmers (high and more regular production) and to exporters (high oil quality). Key words: Olive, Chemlali Sfax, Improvement, Oleic acid, Alternate bearing, Agronomy, Morphology

La pollinisation croisée de la variété d’olive auto-incompatible Meski (Tunisie) a été réalisée par l’interplantation de la variété Picholine (France) dans un champ irrigué dans la zone centrale et continentale de Sidi Bouzid avec une densité de 204 arbres ha-1 (7 m / 7 m). La production d’olives moyenne a été calculée pour chaque arbre Meski sur la période 2006 à 2015. Les arbres ont été regroupés en fonction de la distance minimale par rapport au premier arbre pollinisateur et le nombre de polinisateurs dans les trois premières carrés autour de l’arbre Meski. Les relations de régression entre la production d’olives Meski et sa distance du pollinisateur Picholine d’une part, et entre la production d’olive Meski et le nombre de pollinisateurs Picholine d’autre part, étaient toutes non significatives. Ainsi, le premier arbre pollinisateur pourrait être placé dans le second carré (14 m). Le nombre de pollinisateurs pourrait être 0 dans le premier carré autour de Meski, 1 dans le deuxième carré et 3 dans le troisième carré. Au total, les trois premiers carrés devraient totaliser un maximum de 4 arbres pollinisateurs. Les résultats ont montré une production optimale d’olive avec 8 % des polinisateurs dans les plantations Meski. Ainsi, la faible performance productive de Meski n’est pas seulement due à la faible autopollinisation mais d’autres facteurs seraient également impliqués. Mots clés: Olive, variété Meski, Pollinisation, Tunisie

To enhance table olive tree authentication, relationship, and productivity, we consider the analysis of 18 worldwide table olive cultivars (Olea europaea L.) based on morphological, biological, and physicochemical markers analyzed by bioinformatic and biostatistic tools. Accordingly, we assess the relationships between the studied varieties, on the one hand, and the potential productivity–quantitative parameter links on the other hand. The bioinformatic analysis based on the graphical representation of the matrix of Euclidean distances, the principal components analysis, unweighted pair group method with arithmetic mean, and principal coordinate analysis (PCoA) revealed three major clusters which were not correlated with the geographic origin. The statistical analysis based on Kendall’s and Spearman correlation coefficients suggests two highly significant associations with both fruit color and pollinization and the productivity character. These results are confirmed by the multiple linear regression prediction models. In fact, based on the coefficient of determination (R 2) value, the best model demonstrated the power of the pollinization on the tree productivity (R 2 = 0.846). Moreover, the derived directed acyclic graph showed that only two direct influences are detected: effect of tolerance on fruit and stone symmetry on side and effect of tolerance on stone form and oil content on the other side. This work provides better understanding of the diversity available in worldwide table olive cultivars and supplies an important contribution for olive breeding and authenticity.

The olive trees (Olea europaea L.) have been cultivated for millennia in the Mediterranean basin and its oil has been an important part of human nutrition in the region. In order to distinguish between olive accessions, morphological and biological characters have been widely and commonly used for descriptive purposes and have been used to characterize olive accessions. A comparative study of morphological characters of olive accessions grown in Tunisia was carried out and analyzed using Bayesian Networks (BN) and Principal Components Analysis (PCA). The obtained results showed that averages of fruit and kernel weights were 2.27 grams and 0.41 grams, respectively. Besides, a relatively moderate level of variation (51.22%) being explained by four Principal components. BN revealed that geographical localisation plays a role in the increase of tree habit, size of lenticels and leaf shape. A dendrogram has been carried out in the aim to classify studied olive accessions. We proposed a novel method of analysis based on the three-step scheme, in which first the data set is clustered, then olive tree features are evaluated. The studied accessions can be divided into four main groups by cutting the dendrogram at a similarity value of 0.645. Different relationships are studied and highlighted, and finally the collected features are subjected to a global principal component analysis. Obtained results confirmed that core surface was negatively correlated with geographical location (r = -0.52, p<0.05) and maturation period r = -0.539, p<0.05). Number of lenticels was positively correlated to lenticels size (r = 0.632, p<0.05). Core shape had a negative correlation with fruit shape (r = -0.759, p<0.05). On the basis of these findings, this research confirmed that morphological markers are a preliminary tool to characterize olive oil accessions.