Areas Of Tunisia Research Articles

Occurrence of eyespot of cereals in Tunisia and identification of Oculimacula species and mating types

The objectives of this study were to investigate the occurrence of eyespot in commercial spring cereal crops in four climatic areas in Tunisia and characterize the dominant species of Oculimacula responsible for the disease. A total of 294 wheat, barley and oat fields were surveyed for eyespot incidence and severity during four cropping seasons from 2010 to 2014. Eyespot was identified in 63.5% of the fields with an average incidence of 23.1% infected stems. The number of infected fields as well as the incidence and severity of disease increased significantly during the 5 years of the study. A significant difference in the occurrence of eyespot among the climatic regions was noted with the wetter areas having greater disease incidence. The highest incidence of eyespot was recorded in durum wheat and bread wheat fields, whereas barley was significantly less infected. The effect of previous crop on eyespot incidence was not significant. All 70 isolates collected in this study were identified as O. yallundae and among them, 39 were identified as MAT1-2 and 31 as MAT1-1. This study highlights the influence of climatic conditions on the distribution of eyespot in the cereal growing areas of Tunisia as well as the increasing occurrence of the disease. The predominance of O. yallundae is an important consideration in the choice of integrated management strategies for eyespot. The presence of both mating types of O. yallundae in similar proportions suggests that sexual reproduction may be occurring.

Variability of Pyrenophora tritici-repentis isolated from different wheat areas of Tunisia: Morpho-cultural characterization, pathogenic analysis and virulence effector genes

Sixty-three isolates of Pyrenophora tritici-repentis collected from various wheat areas of the north of Tunisia were characterized and studied for their variability. Under in vitro conditions, morpho-cultural characterization showed the presence of several colors of colonies. An inoculation bioassay was performed identifying the presence of three symptoms type i.e., small brown spots, chlorosis, and necrosis with chlorosis. ANOVA of leaf infected area and lesion length data caused by isolates showed significant difference, and Ascending Hierarchical Clustering discriminated them into two distinct pathogenic profiles. Molecular detection of virulence effector genes demonstrated the presence of ToxA, ToxB, and toxb gene individually or in combination, resulting in five different gene profiles. These results indicate large variability of features. Multiple Correspondence Analysis and Ascending Hierarchical Clustering identified four distinct isolates classes. Both pathogenic profiles of isolates appeared in all the groups. Hence, it was not possible to establish a relationship between variability characters and geographical regions from which the isolates were collected.

Effect of Five Mediterranean Shrubs Extracts on Larval Exsheathment of Haemonchus contortus

Background: Mediterranean shrub species cover more than 70% of the total area in Tunisia and in summer when the herbaceous species have wilted, they constitute feeding resource for livestock. The use of tanniniferous shrubs seems to be a good alternative to control gastrointestinal nematodes infections in small ruminants. This study evaluated the in vitro anthelmintic (AH) effect of Ceratonia siliqua (C. siliqua), Periploca angustifolia Labill. (P. angustifolia) and Medicago arborea (M. arborea) against Haemonchus contortus third stage larvae (L3). Methods: The larval exsheathment assay (LEA) was used to determine the proportions (%) of exsheathment of five acetonic extracts at different concentrations (1200, 600, 300, 150 μg/ml). To confirm the role of tannins in the AH effects of extracts, polyvinyl polypyrolidone (PVPP) was used as deactivating chemical tannins. Result: The highest % L3 exsheathed was recorded for M. arborea (55.01%) and the lowest value was founded for C. siliqua and P. angustifolia leaves (16.26%). Our results were concentration-dependent (P less than 0.001). The % of exsheathment increased as the time of incubation increased (P less than 0.001). P. angustifolia pods recorded the lowest EC50 value (P less than 0.05). After PVPP addition, all the acetonic extracts showed a restoration of L3 exsheathment values similar to control values (P less than 0.001).

Contribution of Tamarix aphylla to soil organic matter evolution in a natural semi-desert area in Tunisia

A soil, classified as Arenosol (Eutri-Aridic Arenosol (Calcaric)), located in Neffatia (Tunisia) and populated by the shrub tamarisk (Tamarix aphylla), was studied to assess how the litter deriving from tamarisk can affect its characteristics. Several parameters were considered: particle size distributions (PSD), pH, cation exchange capacity (CEC), total CaCO3 content, total nitrogen (TKN), phosphorus and total organic carbon (TOC). Down the soil profile the pH increased from 7.83 to 8.32 as a probable consequence of salts accumulation deriving from the mineralization of the organic matter and the limited leaching due to low rainfall. As expected, TOC and TKN decreased, from the top downwards, and the two parameters were well correlated (TOC vs TKN: R2 = 0.98; p < 0.05; n = 3). CEC assumed progressively lower values reflecting the decreasing organic matter content (CEC vs TOC: R2 = 0.93; p < 0.05; n = 3). PSD showed that the presence of roots influenced the quantity of fine particles down the profile and the PSD cumulative curves were indicative of an aeolian origin for the soil parent material, confirming the hypothesis that tamarisk interacts with the environment, trapping sediment and forming the so-called phytogenic dunes. By chemical and spectroscopic analyses, it was possible to assess that tamarisk plant residues directly contributed to the soil organic matter (SOM) accumulation and characteristics. Stable SOM (ligno-humic fraction) closely resembles that of the plant (leaves and stems) and is chemically lacking in the more easily degradable organic components such as fats, hemicellulose, cellulose and proteins. 13C CPMAS NMR spectroscopy showed that the so-called soil ligno-humic fraction consists of aromatic molecules such as tannins, and aliphatic carbon (i.e. cutins and suberins) already present in the plant and preserved by mineralization processes because they are the most resistant to biological degradation.

Phenology as accuracy metrics for vegetation index forecasting over Tunisian forest and cereal cover types

ABSTRACT Different studies on predicting future green cover changes exist with various success levels. Each one focuses on a different story about which model is more appropriate. Therefore, finding a suitable model remains a difficult task due to the remotely sensed data issues and the complexity of the vegetation cover change process. Despite the unicity of vegetation indices time series, the forecasting assessment relies basically on the commonly used forecast error measurements (e.g. Mean Square Error (MSE), Root MSE (RMSE), and the symmetric Mean Absolute Percentage Error (sMAPE), etc.) which may not reflect the real potential of the fitted forecasting model. Herein, the experimentation of forecasting vegetation indices employing two univariate time series models and new accuracy metrics is discussed. Box Jenkins models (Seasonal AutoRegressive Integrated Moving Average (ARIMA) model) and neural network model (nonlinear autoregressive (NAR) model) are applied individually and coupled (NAR-NAR and NAR-ARIMA) based on a multi-resolution analysis-wavelet transform. These models’ forecasting ability is evaluated using 16-days Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index (NDVI) time series data of two different vegetation cover types of northwestern area in Tunisia. The major finding highlights firstly the importance of integration of the decomposition step to show off the hidden components of vegetation indices. The commonly used accuracy measures show that the coupled neural networks model outperforms other models. Then, interesting conclusions were drawn when phenological metrics are used as performance measures. Herein, Box Jenkins forecasting model generates a better NDVI curve shape than hybrid models despite their low RMSE measures. This is mainly due to good estimation of some phenological events, namely, the amplitude, the peak and the season’s length. Generally, Box Jenkin model excels at handling quick variations. By contrast, combined models show better phenological metrics’ estimation when the observations are complex or describe long time periods. Based on these findings, we suggest that the choice of the evaluation metric must be related to the future forecaster interest.

Diversity of rhizobia isolated from Tunisian arid soils capable of forming nitrogen-fixing symbiosis with Anthyllis henoniana

Soils in arid and infra-arid regions of Tunisia (where rainfall does not exceed 180 mm) suffer from rapid degradation of vegetation cover and loss of biodiversity. To limit the progress of desertification, it is necessary to promote the cultivation of autochthonous plants and particularly legumes, pioneer plants used for the restoration of poor soils. 50 strains were isolated from soils of five locations throughout arid areas in Tunisia using Anthyllis henoniana, a woody Saharan legume. 16S rRNA gene sequencing and multilocus phylogenetic analysis using recA and dnaK genes grouped rhizobial isolates into six clades, three of them related to the genus Rhizobium (36%), particularly R. leguminosarum, R. sullae and R. radiobacter, two related to Ensifer (56%), E. meliloti and E. numidicus, and one related to Neorhizobium (8%). Twelve selected strains were assayed for symbiotic efficiency using A. henoniana. Strains related to Ensifer and R. sullae were symbiotically efficient; demonstrating for the first time that they are natural symbionts of A. henoniana in Tunisian arid soils. Strains Ensifer sp. AZ2.5 and Rhizobium sp. AE4.7 were the most efficient in nitrogen fixation, suggesting that these strains could be interesting inoculants to enhance A. henoniana adaptation and growth in poorly vegetated regions.

Pistachio performance in the southern Mediterranean: towards optimal use of genetic resources to increase productivity of rainfed agriculture

Rainfed agriculture in Mediterranean countries is tending to become less productive under an increasingly warming climate. To improve this productivity, optimal use of available resources is of strategic concern. The cultivation of the pistachio (Pistacia vera L.), a species well adapted to arid areas in Tunisia, is, however, a low-productive crop. Little information is currently available on the the high genetic diversity that constitutes the main barrier to the optimal cultivation of this crop. The aim of this study was to improve current knowledge on the behaviour of eight local (“Mateur”, “El Guettar”, “Meknassy”, “LG1” and “LG2”) and foreign (“Ohadi”, “Amiri” and “Jawad”) pistachio accessions currently grown under rainfed conditions in northeastern Tunisia. Phenological events, average nut yield per tree, yield efficiency and nut characteristics were determined during the 2015–2017 crop periods. The results showed variable impacts of warm climate and rainfed growing conditions on the studied accessions. Flower setting occurred ealier in local accessions than in Iranian cultivars that require a higher chill amount. Tree fruit yield varied between 2.8 and 11.1 kg. The “LG2”, “El Guettar” and “Mateur” accessions were the most productive of those tested (10.4–11.1 kg/tree), while accessions “Meknassy”, “Amiri” and “Jawad” accessions performed the least (2.8–3.7 kg/tree). The vigorous “El Guettar” and the low vigorous “Amiri” cultivars showed a higher yield efficiency than did cvs. “Jawad” and “Meknassy” cultivars with high and middle vigour, respectively. “LG2”, “El Guettar” and “Mateur” accessions exhibited better adaptation. “Jawad” cultivar produced the largest nuts while “El Guettar” and “LG1” accessions the smallest. Specific technical practices are suggested to improve yield performances of the studied accessions, including moving pistachio orchards to most favourable climate regions.

The black fig fly Silba adipata (Diptera: Lonchaeidae) as an emerging pest in Tunisia: preliminary data on geographic distribution, bioecology and damage

Frugivorous fruit flies are considered among the most damaging pests of cultivated fruit crops. The most studied ones are those belonging to the Tephritidae family such as the Mediterranean fruit fly (Medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). The black fig fly (BFF) Silba adipata McAlpine (Diptera: Lonchaeidae) is a frugivorous monophagous fly species originating from the Mediterranean Basin and the Middle East. Very few data are available in the literature regarding its bioecology, symptoms, distribution and damage. In 2015, severe fruit losses caused by this pest were reported in numerous fig producing areas in Tunisia. In this study we report for the first time the occurrence of this pest in Tunisian fig plantations. Furthermore, laboratory and field observations performed in the main Tunisian fig production areas allowed to address the geographic distribution and the pest status in Tunisia and to characterize its symptoms. We found that the BFF is widely distributed in Tunisia as it was present in all 12 prospected fig producing areas. Moreover, field monitoring of the infestation rates on caprifigs (male fruits) and figs (female fruits) of many cultivars, types (Caprifig, Common, San Perdro and Smyrna) and crops (first and second crops) in three main Tunisia production areas (Djebba, Chott-Mariem and Medenine) allowed to assess its damageability. We showed that it caused high losses on figs and caprifigs. Maximum cumulated infestation rates of caprifigs were registered on cultivar Wedlani (81.25%) in the region of Medenine while the highest infestation rates of figs were registered on the first crops of the San Pedro cultivars Wahchi Thibar (88.17%), Thguegli Thibar (73.98%) and Khenziri (43.75%) in the region of Chott-Mariem. Consequently, the BFF should be probably considered as an emerging economic pest of caprifigs and figs in Tunisia. Possible control methods are explored and discussed.

Effect of Three Soil Tillage Practices on Soil Organic Matter and Nutrient in Any Semi-Arid Area in Tunisia

The distribution of soil organic matter (SOM), nitrogen (N), potassium (K), total calcium carbonate (CaCO3) and pH was studied in relation to three soil tillage practices: conventional (CT) using mouldboad plough followed by three crossing of off-set disc harrow, tooth harrow and seed drill, Reduced (RT) using a chisel, and no-till (NT) using direct driller and 2 plant species: Vicia faba and Durum wheat, grown in a clayey soil of the semi-arid region of Kef (North western Tunisia) during three years 2009-2011.&#x0D; Results showed that, under NT, Vicia faba increased SOM and N in the first fifteen centimeters by 20% and 84% respectively as compared to the CT, and reduced soil pH by 0.1 unit. Indeed, Vicia faba benefited from the residues of the Durum wheat. In contrast, CT buried the residues of the previous crop increasing the rate of SOM and N in the subsoil (30-45 cm depth). This made clear that NT, had the benefit of improving top-soil fertility and putting soil nutrients at the reach of the Vicia faba plant roots. Moreover, NT increased the concentration of K in the top-soil which helped seedlings and young plants resisting biotic and non biotic stresses imposed by the semi-arid environment.

Response of olive tree to ammonium nitrate fertilization under saline conditions

Water scarcity and salinity are major concerns for the new intensive olive groves in arid and semi-arid areas in Tunisia. Furthermore, an inadequately applied fertilization program should aggravate the problem of salinity. The main aim of the present study is to assess the effects of salinity and ammonium nitrate (AN) on the behavior of olive plants (Olea europaea L.var. Arbequina). The experiment was performed with four NaCl levels (0.5, 50, 100, and 150 mM) combined with three levels of NH4 NO3 (0, 50, 100 g) by adding the nutrient solution of ½ Hoagland. Salinity had a statically significant negative effect on the considered responses, although the severity of the effect varies among treatments. High concentrations of salt (100, 150 mM) decreased vegetative growth, the production of fresh and dry biomass, leaf area, chlorophyll concentration, and increased leaf succulence. Similarly, salinity induced an accumulation of toxic ions and loss of electrolytes in the leaves. The use of ammonium nitrate is noticed to be ineffective in improving various growth and physiological parameters of olive plants grown under saline conditions, and it depressed all studied parameters mainly at the highest dose. This depression could be attributed to an increase in leaf sodium concentration after ammonium nitrate application, in spite of the increase of leaf nitrogen concentration. A better management of nitrogen fertilization in saline conditions should be considered mainly in relation to the right source.

An improved trend vegetation analysis for non-stationary NDVI time series based on wavelet transform.

The aim of this paper is to improve trend analysis for non-stationary Normalized Difference Vegetation Index (NDVI) time series (TS) over different areas in Tunisia based on the wavelet transform (WT) multi-resolution analysis (MRA-WT), statistical test, and meteorological data. The MRA-WT was applied in order to decompose the TS into different components. However, the most challenge for TS analysis using MRA-WT laid in the selection of two optimum parameters: the level of decomposition and mother wavelet (MW). In this work, both factors were investigated. Firstly, the level of decomposition was calculated for 18 different MWs, and secondly the energy to Shannon entropy ratio criterion was investigated to choose the most suitable MW. The Mann-Kendall test (MK) and Sen's slope were applied to the last approximation component in order to analyze long-term vegetation changes. Finally, the influence of meteorological data for trend was analyzed. The results were first computed for different sites in Tunisia using MODIS NDVI TS from 2001 to 2017. The obtained results proved the importance of MW selection. Level 5 was considered for the TS as the best level of decomposition for long-term vegetation changes. The Daubechies and Symlets MWs (db9 and sym4) showed the highest energy to entropy ratio for three selected vegetation canopies. A combination of the two MW was proposed to derive a trend vegetation analysis at image level. A degradation in the forest area and a few increases in cropland and vegetation area were presented.

Modeling the Effects of Irrigation Water Salinity on Growth, Yield and Water Productivity of Barley in Three Contrasted Environments

Freshwater scarcity and other abiotic factors, such as climate and soil salinity in the Near East and North Africa (NENA) region, are affecting crop production. Therefore, farmers are looking for salt-tolerant crops that can successfully be grown in these harsh environments using poor-quality groundwater. Barley is the main staple food crop for most of the countries of this region, including Tunisia. In this study, the AquaCrop model with a salinity module was used to evaluate the performance of two barley varieties contrasted for their resistance to salinity in three contrasted agro-climatic areas in Tunisia. These zones represent sub-humid, semi-arid, and arid climates. The model was calibrated and evaluated using field data collected from two cropping seasons (2012–14), then the calibrated model was used to develop different scenarios under irrigation with saline water from 5, 10 to 15 dS m−1. The scenario results indicate that biomass and yield were reduced by 40% and 27% in the semi-arid region (KAI) by increasing the irrigation water salinity from 5 to 15 dS m−1, respectively. For the salt-sensitive variety, the reductions in biomass and grain yield were about 70%, respectively, although overall biomass and yield in the arid region (MED) were lower than in the KAI area, mainly with increasing salinity levels. Under the same environmental conditions, biomass and yield reductions for the salt-tolerant barley variety were only 16% and 8%. For the salt-sensitive variety, the biomass and grain yield reductions in the MED area were about 12% and 43%, respectively, with a similar increase in the salinity levels. Similar trends were visible in water productivities. Interestingly, biomass, grain yield, and water productivity values for both barley varieties were comparable in the sub-humid region (BEJ) that does not suffer from salt stress. However, the results confirm the interest of cultivating a variety tolerant to salinity in environments subjected to salt stress. Therefore, farmers can grow both varieties in the rainfed of BEJ; however, in KAI and MED areas where irrigation is necessary for crop growth, the salt-tolerant barley variety should be preferred. Indeed, the water cost will be reduced by 49% through growing a tolerant variety irrigated with saline water of 15 dS m−1.

The long-run effects of energy use, urbanization and financial development on carbon dioxide emissions

PurposeThis study aims to fill the gap in existing studies that have analyzed the drivers of carbon dioxide (CO2) emissions. The author investigate the long-run effects of energy types, urbanization, financial development and, the interaction between urbanization and financial development on CO2 emissions.Design/methodology/approachStochastic impacts by regression on population, affluence and technology model served as the framework for empirical modeling. Using annual time-series data for Tunisia, autoregressive distributed lag bounds test was used to examine the cointegration of the variables. Also, the fully modified ordinary least squares was used to estimate the emission effect of the explanatory variables. Further investigations were done using the principal component analysis and variance decomposition analysis.FindingsIncome, urbanization, trade and financial development exert upward pressure on CO2 emissions. However, the interaction between urbanization and financial development reduces the emission of CO2. Furthermore, primary energy use, energy intensity, electricity consumption and fossil fuel consumption have positive effects on carbon emission, while combustible renewables and waste, and electricity production from natural gas have negative effects on carbon emission.Practical implicationsThe policy implication/recommendation indicates that the financial sector’s authorities can combat carbon emission by properly regulating the development and activities of the financial sector in urban areas in Tunisia. The promotion of the development and usage of cleaner energy is recommended to help reduce carbon emission. Policymakers need to promote environmentally friendly economic growth and development agenda.Originality/valueThe contribution of this study to the environmental degradation literature is that it offers evidence from Tunisia, which has not received much empirical attention. It also examines the effect of various forms of energy usage on carbon emission. To the best of the author’s knowledge, this is the first study to examine the interaction effect between urbanization and financial development on carbon emission. Also, if not the first, this study is among the earliest to use the principal component analysis as a part of the prediction of the carbon emission effect of energy variables.

Mycotoxins presence in pre- and post-fermented silage from Tunisia

Silage represents a major part of the feed ration for livestock, being a potential cause of mycotoxicosis as it can be contaminated with toxigenic fungi capable of producing mycotoxins in suitable environmental conditions.In the present work, the presence of natural mycotoxins in samples collected of silage from the main producing areas in Tunisia (Ariana, Bizerte, Béjà and Jendouba) was assessed based on different plant material (oat, barley, triticale, artichoke, sulla or raygrass). Mycotoxins were evaluated during three periods in green forage (P1) and subsequently in ensiled products after 60 days (P2) and 100 days (P3) of fermentation. Samples were extracted by a QuEChERS procedure and analyzed by mass spectrometry for the determination of 23 mycotoxins. The results showed the presence of Fusarium mycotoxins, deoxynivalenol (DON), HT-2 toxin, zearalenone (ZEA), enniatins (ENA1, ENB, ENB1) and beauvericine (BEA); as well as one Alternaria mycotoxin tentoxin (TENT). The highest values detected were for DON in the three periods. DON maximum value were 381, 2053 and 916 µg/kg for P1, P2 and P3, respectively. This study demonstrated the presence of fungi and DON, ZEA and ENs contamination in Tunisian silage without a recognized risk on the ruminants or further in humans. However, a continuous enhancement of the silage quality, and management and control of mycotoxins, should be implemented to ensure safe ensilable plant material.

Does Arbuscular Mycorrhiza Determine Soil Microbial Functionality in Nutrient-Limited Mediterranean Arid Ecosystems?

Arbuscular mycorrhizal fungi (AMF) are determinant for the performance of plant communities and for the functionality of terrestrial ecosystems. In natural ecosystems, grazing can have a major impact on mycorrhizal fungi and consequently on plant growth. The objective of this study was to evaluate the statements referred above in Mediterranean arid areas in Tunisia. Root samples and rhizosphere soils of five dominant herbaceous plants were studied at six distinct arid sites differing on soil proprieties and grazing intensity. At each site, chemical and dynamic properties of the soil were characterized as well as the AMF colonization intensity and the soil functionality. Results showed that the mycorrhizal frequency and intensity and spore density, varied between plants in the same site and, for each plant, between sites and evidenced a positive effect of mycorrhized plants on soil microbial activity. Grazing and soil properties strongly affected AMF composition and the soil microbial and biochemical dynamics, which presented the lowest values at the sites with the highest grazing intensities. In conclusion, these results demonstrate that AMF improve soil biological properties, supporting the hypothesis that mycorrhiza and grazing compete for plant photosynthates, and highlight the importance of mycorrhizal symbiosis towards soil functionality under arid conditions.

Techno-Economic Analysis of Micro-Grid Based Photovoltaic/Diesel Generator Hybrid Power System for Rural Electrification in Kerkennah, Tunisia

Abstract This paper scrutinizes the techno-economic feasibility of a solar hybrid off-grid power system, in a rural area in Tunisia. Hybrid Optimization of Multiple Energy Resources (homer) is used for the design and the optimization of a hybrid photovoltaic (PV)/diesel power system consisting of photovoltaic panels, a diesel generator, a converter, and a battery bank. A sensitivity analysis is carried out to investigate the impact of the key system parameters such as the average load, the diesel fuel price, and the reliability constraints on the system outputs and performance. Sensitivity analysis is also used to compare different system configurations and to identify thresholds and situations in which one configuration is more cost-effective than another. Three system types are considered: PV/battery, PV/diesel/battery, and diesel/battery. The results showed that beyond a certain load threshold, the hybrid system is the most cost-effective and that micro-grid projects based on hybrid PV/Diesel power systems can be a solution for rural electrification in Tunisia where there is no possibilities for the national electric grid extension.

Screening of five marine-derived fungal strains for their potential to produce oxidases with laccase activities suitable for biotechnological applications

BackgroundEnvironmental pollution is one of the major problems that the world is facing today. Several approaches have been taken, from physical and chemical methods to biotechnological strategies (e.g. the use of oxidoreductases). Oxidative enzymes from microorganisms offer eco-friendly, cost–effective processes amenable to biotechnological applications, such as in industrial dye decolorization. The aim of this study was to screen marine-derived fungal strains isolated from three coastal areas in Tunisia to identify laccase-like activities, and to produce and characterize active cell-free supernatants of interest for dye decolorization.ResultsFollowing the screening of 20 fungal strains isolated from the harbors of Sfax and Monastir (Tunisia), five strains were identified that displayed laccase-like activities. Molecular-based taxonomic approaches identified these strains as belonging to the species Trichoderma asperellum, Stemphylium lucomagnoense and Aspergillus nidulans. Among these five isolates, one T. asperellum strain (T. asperellum 1) gave the highest level of secreted oxidative activities, and so was chosen for further studies. Optimization of the growth medium for liquid cultures was first undertaken to improve the level of laccase-like activity in culture supernatants. Finally, the culture supernatant of T. asperellum 1 decolorized different synthetic dyes belonging to diverse dye families, in the presence or absence of 1-hydroxybenzotriazole (HBT) as a mediator.ConclusionsThe optimal growth conditions to produce laccase-like active cell-free supernatants from T. asperellum 1 were 1.8 mM CuSO4 as an inducer, 1% NaCl to mimic a seawater environment and 3% sucrose as a carbon source. The culture supernatant of T. asperellum 1 effectively decolorized different synthetic dyes belonging to diverse chemical classes, and the presence of HBT as a mediator improved the decolorization process.

Characterization of mycotoxigenic Alternaria species isolated from the Tunisian halophyte Cakile maritima

Cakile maritima is a typical halophyte of the Mediterranean coasts. In addition to its ecological and industrial properties, C. maritima has antiscorbutic, diuretic and purgative roles in folk remedies. This plant is infected by different fungal species, mainly belonging to Alternaria genus. Two-hundred Alternaria strains were collected from four different pedo-climatic areas in Tunisia, from C. maritima fresh plant tissues showing symptoms of Alternaria infection. Phylogenetic analyses of 79 representative Alternaria strains, were carried out using multi-locus gene sequencing. All the strains clustered in the Alternaria Section: 47 strains had high homology with A. alternata reference strain, 13 grouped with A. arborescens reference strain, 12 grouped with A. mali reference strain, and seven strains were not well defined with A. mali as their closest species. In vitro production of tenuazonic acid (TA), alternariol (AOH), alternariol-monomethyl ether (AME), and altenuene (ALT) was evaluated. Approx. 68% of strains simultaneously produced AOH, AME and TA. Only two A. alternata and one A. mali strains were ALT producing. Pathogenicity tests on leaves of C. maritima were carried out with 41 representative strains. Alternaria arborescens showed the greatest pathogenicity compared to A. alternata and A. mali, although no statistically significant differences in pathogenicity were observed. This is the first study on Tunisian populations of Alternaria species isolated from the extremophile C. maritima.

An eco-friendly epoxy polymer binder for the treatment of Tunisian harbor sediments: Laboratory investigations for beneficial reuse.

The management of dredged sediments poses serious environmental and economic problems because of their geochemical properties and in particular their pollutant content. In this research, marine sediments from Tunisian harbors were collected to study their beneficial reuse as construction materials using an eco-friendly polymer binder. Experimental investigations include the determination of physicochemical, mineralogical, and environmental parameters of sediments from the Sidi Mansour and Sidi Youssef areas in Tunisia. Prismatic mortar samples (4 × 4 × 16 cm) were prepared at laboratory scale using normalized sand and epoxy resin. Then their composition was modified by including a sediment fraction in the substitution of sand at rates ranging from 10 to 50% in dry mass. After a 7-day curing period, mortar samples were submitted to mechanical, physicochemical, and environmental analyses. Mortar samples including sediment fractions displayed lower strength than sand mortar used as control. This result is explained by the increase of porosity values in the mortar samples when sediment samples were incorporated. A positive relationship between porosity and compressive strength values was evidenced, suggesting that the compactness of granular skeleton could play an important role in the preparation of materials. From an environmental point of view, the mortar samples containing sediment fractions showed relatively low leaching levels, which confirms their suitability for the manufacturing of construction materials.

Local livelihoods and land users’ perceptions of land degradation in northwest Tunisia

Understanding land users’ livelihoods and their strategies is essential in order to adapt prevention and adaptation policies and to ensure sustainable land management (SLM) planning. Considering the global call for SLM, and due to a lack of studies on land degradation (LD) in Tunisia, we aimed to explore the livelihoods of farmers, their livelihoods strategies and perceptions about LD and land management, in order to design SLM in rural areas in Tunisia. We used the Sustainable Livelihoods Approach (SLA) to analyse the livelihoods assets, livelihoods strategies, and the perceptions of people about LD and SLM. Through structured interviews with 90 households, we collected both quantitative and qualitative data on household assets, strategies, and perceptions. Results indicate variation in the status of livelihoods among households, which influences their livelihoods strategies and consequently livelihoods outcomes. When facing environmental issues, farm households apply various livelihoods strategies to shield themselves from negative impacts and shocks. Our study revealed that farmers in the high-livelihoods-assets category chose economic returns over environmental benefits. Farmers in the low-livelihoods-assets category have generated livelihoods strategies that lead to inappropriate management strategies due to low access to assets and, as a result, contributed to LD. This is because these farmers are more concerned about the immediate constraints of their livelihoods and subsistence than the medium and long-term sustainable land management. Compared to the other two groups, farmers in the medium-livelihoods assets category have the best perceptions and flexibility for SLM compared to the other two categories. Thus, as the quality of land is highly dependent on the way it is managed, environmental and land management planning, and policies should not only consider the rehabilitation of land but also require a better understanding of the livelihoods, strategies and perceptions of people as these remain key drivers that affect land condition.