Étude de la croissance et du développement d'Acacia Cyanophylla sur différents substrats provenant de déchets solides municipaux

 
Abstract - Our work aims at the application of several biological and chemical parameters in order to determine the impact of variation in the levels of heavy metals and mineral elements in the soil for the growth of a forest plant Acacia cyanophylla since plants are good indicators of environmental pollution. We studied the impact of heavy metals on the germination and growth of Acacia cyanophylla cultivated in the soil of the three-controlled municipal solid waste of the Northwest of Tunisia and compared with plants of the same species cultivated in non-contaminated soil and soil receiving a mixing of a contaminated soil and a nursery soil. Morphological Parameters (stem height, root length, leaf area, the ratio of the stem / root and biomass) was measured. In the different substrates used, the morphological parameters vary significantly for the different criteria studied. 

Keywords: municipal solid waste, heavy metals, morphological parameters, forest.

Read more

L'utilisation de la télédétection satellitaire et des systèmes d'informations géographiques dans le suivi de la dynamique des nappes alfatières. Cas de la délégation de Hassi el Frid du gouvernorat de Kasserine en Tunisie

Abstract - Esparto grassland in Tunisia covers approximately 452.000 ha, mainly located in central Tunisia. Esparto grassland provides numerous goods and environmental services like fodder production for the livestock, fighting desertification and climate change mitigation. Esparto grassland are threaten by the up-growing anthropogenic pressure (overgrazing, farming…). Local managers need an efficient tool to monitor ecosystems that are managing. This study provide a methodological approach based on easy and free GIS and Remote Sensing data and tools that could be easily handled by local managers to asses land use changes. In our case, we applied this methodology in Hassi El Frid, Kasserine, to assess changes in Esparto grassland. We have found that areas initially covered with Esparto grassland were converted in Olive trees plantation, cereals fields and Cactus respectively 55%, 35% et 7%.

Keywords: Remote Sensing, Land Use Change Assessment, Esparto Grassland, Kasserine.

Read more

Variabilité interspécifique de la morphologie des feuilles entre les arbres adultes et les semis de deux espèces de chêne, (Quercus canariensis Willd.) et (Quercus suber L.) et leur hybride (Quercus afares Pomel) au Nord-Ouest de la Tunisie

 
Abstract- The variability of the leaves has been studied by many authors for the identification of forest species among themselves as in the genus Quercus. In this genus, several taxonomic groups are known by their complex patterns of variation that lead to problems in identifying taxa at the species level. In Tunisia the genus Quercus is the major constituent of the forest, represented by five species. In order to characterize the morphology of the hybrid Quercus afares Pomel with respect to parental species (Quercus canariensis willd and Quercus suber L), we studied the morphological variability of leaves in the adult stage and to progress in understanding the differences between the hybrid and parents, it was important to check whether morphological discrimination was still possible at the planting stage. The leaves were sorted by plant and then scanned. The images were thresholded and processed with Image J software (1.43). Morphological variables of size and shape were evaluated, we described the variability using an analysis of variance (ANOVA) and a Multiple Component Analysis (MCA). The results revealed a high level of diversity in both the adult and seedling stages, with a higher overlap between Q. afares and Q. canariensis than between Q. afares and Q. suber. The hybrid was different from parents for most traits and positioned intermediate for size traits, whereas it was different for shape traits. Q. suber and Q. canariensis remained morphologically distinct. The study resulted in interspecific discrimination with three distinct groups corresponding to the species and forming a gradient. They are arranged from small circular and round leaves (Q. suber) to elongated, slightly lobed leaves (Q. afares) and finally large, lobed leaves corresponding to leaves of Q. canariensis.

Keywords: Foliar morphology, variability, Quercus, hybrid.

Read more

Comparaison de la composition chimique et de l’Activité antioxydante des feuilles de Caroubier (Ceratonia siliqua L.) collectées dans trois sites de Djebel Zaghouan (Tunisie)

Abstract - The carob tree leaves (Ceratonia siliqua L.) collected from National Park of Djebel Zaghouan in three different sites are analyzed for their fatty acid composition, phenolic compounds and antioxidant activity. Total lipids were extracted by an organic solvents mixture. The fatty acid composition was determined using gas chromatography (GC-FID). The total phenolic and total flavonoid contents of dry extract of leaves was evaluated using Folin-Ciocalteu method. The antioxidant activity was tested by the DPPH free radical scavenging assay. Results showed that total fatty acid content varied from 45.22 to 21.33 mg/g dw. Twelve fatty acids were identified and linolenic acid is the predominant fatty acid (29.40–35.78%), followed by linoleic acid (14.02–15.88%), stearic acid (14.03–14.98%) and palmitic acid (5.24–13.87%). The oil contains from 54.68 to 62.52% unsaturated fatty acid. The contents of total phenols ranged from 2.50 to 6.45mg EGA/g dw. The amount of flavonoids varies from 3.42 to 7.42 mg EQ/g dw. Moreover, the evaluation of antioxidant methanolic extract showed a very important activity expressed (70.29–83.70%). These results indicated that the leaves of carob tree have different richness in unsaturated fatty acids following sites and the extracts tested have an antioxidant effect.

Keywords: Ceratonia siliqua L., Phenolic compounds, Flavonoids, Total lipids, Antioxidant activity, Tunisia.

Read more

 
Abstract - To ensure better intervention and, in order to contribute to sustainable management of the environment, natural substances such as essential oils are used as insecticides. In this context, Mentha pulegium was used for its insecticidal activity against larvae of Orgyia trigotephras. Essential oil was diluted in ethanol (96%) to prepare 3 test solutions (S₁=0.05%, S₂=0.10%, and S₃=0.50%). The essential oil was tested by contact action. Larvicidal effect of essential oil was appreciated by comparison to Decis (positif test) and ethanol (negatif test). For each instar a total of 300 larvae were used for the test. Six replications were performed, in each 10 larvae were used. One larva was placed in a Petri dish and 10 µl of each oil solution prepared. The effects of the essential oils, Decis and ethanol were evaluated by measuring the mean mortality time of larvae (MMT). Results showed a highly significant difference between the three concentrations. The 3^rd concentration of M. pulegium is the most effective of the other concentrations. MMT was 15 min for the 3^rd instar, 27 min for the 4^th instar and 1 h 15 min for the 5^th instar. Larvicidal activity of M. pulegium was more efficient on the 3^rd instar than the others. A total of 23 compounds of the essential oil of flowers of M. pulegium were identified. Polegone was the dominant one at 56.22% seems to be responsible for the larvae mortality. This work should be complemented by histological sections of the caterpillars to identify the insecticidal effect of M. pulegium essential oil.

Keywords: contact action, 3 test solutions, chemical composition, mean mortality time, positif test, negatif test.

Read more

 Abstract - During a flood event, the decision maker needs a simple and closer to reality tool to make the proper decisions, such as; the release of dams, the risk knowledge to protect the villagers from the floods. This article presents the construction of a simple flood-forecasting tool at the main stations of the Medjerda, upstream Sidi Salem dam, which will serve for the management of dams and floods of the Medjerda.The phenomenon of floods is seriously arising in the upper Medjerda valley, precisely in Bensalem’s plain upstream Sidi Salem’s dam. To be able to manage the risk of flooding, decision-makers need a simple and rapid tool. Flood prediction results with propagation models are satisfactory. Therefore, we have created an application under MATLAB based on these models. This application requires only upstream’s instant flows to predict downstream’s flows while the coefficients basis of the models, are made from the reconstruction of historical floods. The calculation delay time is evaluated from 2 to 8 hours with a step of 2. The application has been validated using the flood of February 2015. The results were satisfactory with significant Nash coefficients. It has been stated that as the delay is low, the Nash coefficient is better. Propagation models are effective as a tool for flood forecasting, although the Medjerda basin is heterogeneous in terms of the physical characteristics as soil. This application will be connected to the data collection system for real-time forecasting.

Keywords: Flood forecasting, flow propagation model, MATLAB programming, alert system.

Read more