Oases Of Tunisia Research Articles

Study of the nutritional quality of peas (Pisum sativum L.) under different conservation conditions

Peas (Pisum sativum L.) are among the most widely cultivated legumes, known for their adaptability to dry and warm environments and their high nutritional value. This research aimed to investigate the biochemical diversity of proteins, polyphenols, flavonoids, tannins, and antioxidant activity in a local population of peas from the Mareth oasis in Tunisia under different preservation methods: fresh, frozen, canned, and dried. The hypothesis was that preservation methods significantly impact the nutritional quality of peas, with fresh peas retaining the highest levels of essential nutrients. The results showed that fresh peas had superior nutritional quality, demonstrating the highest concentrations of protein (39 mg/g MF), polyphenols (0.17 mg GAE/g MF), flavonoids (0.086 mg QE/mg MF), and antioxidants (52%). In contrast, dried peas exhibited the lowest nutrient levels, particularly in protein and antioxidant activity. The study highlighted that freezing is an effective method for preserving the nutritional integrity of peas compared to canning and drying, which significantly reduce essential nutrient levels. Understanding the effects of various preservation techniques is crucial for maintaining the nutritional quality of peas. These findings have significant implications for consumers and the food industry, advocating for practices that prioritize the retention of nutrients in preserved peas. This research contributes to the ongoing discourse on food preservation methods and their impact on nutritional quality, providing insights that support better choices in food processing and consumption.

The internal structure of spring mounds of Nefzaoua oasis in Tunisia: Formation of an original geomorphic structure

AbstractSpring mounds are specific geomorphological landforms in arid or semi‐arid environments associated with playas and artesian springs. Spring mounds are found worldwide, especially in the great Artesian Basin of Australia and in North American and Egyptian deserts. They result from an exceptional succession of climatic, geomorphological and hydrogeological conditions, with processes that follow each other in a specific order. In Tunisia, in the arid zone, ca. 126 spring mounds have been identified in Nefzaoua province alone, especially in the oasis east of Chott el Jerid. They have a conical shape that ranges from 200 to more than 2000 m in diameter and 3–30 m tall, and their centre is hollowed out by an artesian spring of fresh water. Palm groves (Phoenix dactylifera) spread out at the foot of each mound. The springs have dried up because of the proliferation of borehole wells. Because of the low electric conductivity (EC) of the sediments (<1 mS cm−1) at their base, spring mounds have been excavated and used as a soil amendment to expand new palm plantations. This excavation allows for analysis of their internal structure, which has never been observed well. In the present study, fine analysis of sediment layers in four sections of two representative mounds showed that vegetation had trapped sediment at their base. Fine strata of variable texture alternating with variable calcium carbonate, gypsum or organic carbon contents suggest a clear limnic origin. Many redoximorphic features, sometimes associated with the presence of old roots, suggest variation in the water level in the centre of the mound. The mounds are capped by a thick layer of indurated gypsum, which helps them resist hydric and aeolian erosion. The origin of the sediment components is discussed.

Spring mounds of the Nefzaoua oases in Tunisia: Irreversible degradation of exceptional geomorphic structures

The oases in the arid the Nefzaoua region in central-western Tunisia are associated with spring mounds. Spring mounds result from an exceptional succession of geomorphological, hydrogeological and climatic conditions and processes that follow each other in a specific order. They look like small volcanoes that range from 200 m to more than 2000 m in diameter and 3–30 m in height, which centres were once occupied by a pond fed by an artesian spring. They are at the origin of each oasis's irrigation system, which radiates from the mound's foot. Due to intense irrigation of intensive date palm plantations (Phoenix dactylifera) in recent decades, all artesian springs dried out. We established a complete inventory and typology (i.e. location, dimension, and types of degradation) of all spring mounds in the Nefzaoua region. Overall, in an area of 3000 km2, 126 spring mounds of 7 types were identified, of which 112 (89%) were degraded. Due to the low salt content in spring mound sediments, they are excavated and used as a soil amendment to expand new palm plantations. Only 14 mounds (11%) are presently preserved. Their qualification as a geomorphosite could preserve them from complete destruction.

Etude comparative des composés biochimiques de 12 accessions locales de piment (Capsicum annuum L.) des oasis tunisiennes

Le Capsicum annuum est parmi les cinq espèces Capsicum domestiquées (frutescens, annuum, baccatum, chinense et pubescens) le plus cultivé dans le monde. Il s'adapte assez bien, au milieu sec et chaud. Il est d’une réelle importance socio-économique, capable, de fournir une production de fruits consommés frais ou sous forme de produits peu transformés (piment conservé, piment séché, épice, etc.) de valeur nutritive élevée. L’objectif de cette recherche était d’étudier la diversité biochimique : capsaïcine, dihydrocapsaicine, fer, potassium, magnésium, sodium, zinc, flavonoïdes et acides phénoliques contenus dans une collection de piment provenant de différentes zones d’oasis en Tunisie (Gabès, Kbeli et Tozeur). La caractérisation de ces éléments a été identifié en utilisant la méthode HPLC et la spectrophotométrie d’absorption atomique. On constate une grande variabilité entre les localités de point de vue richesse en composés chimique (coefficient de variation % entre 43 et 108%).
 La récupération de ces anciennes provenances, qui ont été remplacé par des cultivars commerciaux provoquant une érosion génétique dans cette culture, devraient être capitale pour le maintien d’une agriculture durable.

Unlocking the Patterns of the Tunisian Durum Wheat Landraces Genetic Structure Based on Phenotypic Characterization in Relation to Farmer’s Vernacular Name

During the 1970s, Tunisian durum wheat landraces were replaced progressively by modern cultivars. These landraces are nowadays maintained by smallholder farmers in some ecological niches and are threatened gradually by extinction resulting in the narrowing of the genetic diversity. This study aims to investigate patterns of phenotypic variability using twelve quantitative traits in a panel of 189 durum wheat landraces and seven checks, based on farmer’s population name attribution and genetic structure. Our results showed high phenotypic variability among and within landraces and checks for ten out of twelve studied traits. The principal components analysis showed similar grouping using farmers name attribution and genetic structure using K = 6. These results confirmed the identification of a new gene pool in the oases of Tunisia, represented by the sub-population Jenah Zarzoura and the robustness and high relationships between phenotypic and genome-wide genetic structure using DArTseq method. These findings will enhance the conservation efforts of these landraces and their use in breeding efforts at national and international levels to adapt to dry conditions.

Agroforestry Heritage Systems as Agrobiodiversity Hotspots. The Case of the Mountain Oases of Tunisia

Traditional agricultural systems are receiving increasing attention at the international level due to their multifunctional role. The Globally Important Agricultural Heritage Systems (GIAHS) programme of the Food and Agriculture Organization (FAO) aims to identify agricultural systems of global importance, preserve landscape, agrobiodiversity and traditional knowledge and apply the principles of dynamic conservation to promote sustainable development. Biodiversity associated to traditional agricultural practices is particularly important, especially in difficult environments, like traditional oases, for ensuring food and nutrition to local communities. We documented landscape and biological diversity associated with traditional agricultural practices in three traditional oases in Tunisia, through a landscape analysis based on land-use survey, and an assessment of cultivated species. Results show that the landscape structure is dominated by agricultural land uses and characterized by a high level of diversification. Agrobiodiversity is high: we identified 20 varieties of date palm, 21 species of fruit trees, 21 vegetable species and two fodder crops. Results highlighted that traditional oases, as other agroforestry and agricultural heritage systems, continue to play a crucial role in maintaining genetic resources and agrobiodiversity. Farmers who, all over the world, still cultivate applying traditional practices are the main actors that practice a real conservation of genetic resources and diversity by maintaining traditional cultivars and a diversified landscape structure. Our methodology, based on the combined assessment of land uses and agrobiodiversity, can be replicated in other agricultural heritage systems to evaluate and measure possible transformations and identify the best strategies for their preservation.

Monitoring vegetation dynamics in southern Tunisia using SPOT-5 (Take5) data: a case study of the Tozeur oases

Spatial data on vegetation dynamics are sparse for the Djerid oases of Tunisia, but such data are urgently needed by policy makers for natural resource management purposes. These data can be collected by remote sensing and analyzed using Geographic Information System software. We analyzed the changing dynamics of the Tozeur oases in southwestern Tunisia using normalized difference vegetation index (NDVI) index data that were generated from SPOT-5 (Take5) satellite imagery taken from April to September, 2015. We used agglomerative hierarchical clustering (AHC) to produce a dendrogram that segmented the area into similar NDVI classes, then analyzed these clusters with reference to ground-truth data collected by field surveys. The unsupervised classification map produced by AHC represents a spatial model of the NDVI distribution in the oases. The results revealed seven different clusters with very high spatial heterogeneity that were linked to biophysical parameters in the field.

The date palm tree rhizosphere is a niche for plant growth promoting bacteria in the oasis ecosystem.

In arid ecosystems environmental factors such as geoclimatic conditions and agricultural practices are of major importance in shaping the diversity and functionality of plant-associated bacterial communities. Assessing the influence of such factors is a key to understand (i) the driving forces determining the shape of root-associated bacterial communities and (ii) the plant growth promoting (PGP) services they provide. Desert oasis environment was chosen as model ecosystem where agriculture is possible by the microclimate determined by the date palm cultivation. The bacterial communities in the soil fractions associated with the root system of date palms cultivated in seven oases in Tunisia were assessed by culture-independent and dependent approaches. According to 16S rRNA gene PCR-DGGE fingerprinting, the shapes of the date palm rhizosphere bacterial communities correlate with geoclimatic features along a north-south aridity transect. Despite the fact that the date palm root bacterial community structure was strongly influenced by macroecological factors, the potential rhizosphere services reflected in the PGP traits of isolates screened in vitro were conserved among the different oases. Such services were exerted by the 83% of the screened isolates. The comparable numbers and types of PGP traits indicate their importance in maintaining the plant functional homeostasis despite the different environmental selection pressures.

Alterations in lignin content and phenylpropanoids pathway in date palm (Phoenix dactylifera L.) tissues affected by brittle leaf disease

Brittle leaf disease or Maladie de la Feuille Cassante (MFC) is a lethal disorder of date palm that has assumed epidemic proportions in the oases of Tunisia and Algeria. No pathogen could ever be associated with the disease, while leaflets of affected palms have been previously shown to be deficient in manganese. The work reported here aims to understand the biochemical basis of the date palm response to this disorder. Since the typical disease symptom is the leaf fragility, we have investigated lignin content in leaves and roots. Strong decrease in total lignin content was observed in affected leaves, while lignin content increased in affected roots. Histochemical analyses showed hyperlignification thicker suberin layer in roots cortical cells. The phenylpropanoids pathway was also disrupted in leaves and roots, cinnamoyl-CoA reductase and cinnamyl-alcohol dehydrogenase gene expression was affected by the disease which severely affects the cell wall integrity.

DRAINAGE PERFORMANCE ASSESSMENT IN A MODERNIZED OASIS SYSTEM

ABSTRACTSaharan oases are frequently subjected to waterlogging due to the presence of shallow and salty groundwater and poor irrigation and drainage conditions. To overcome this problem in Tunisia, in 2002 an official modernization programme was implemented based on two operations: (i) increasing irrigation efficiency by building concrete irrigation canals to limit losses due to water percolation and (ii) controlling waterlogging and salinity by installing a subsurface drainage system in place of the traditional open‐ditch system. In this study, a salinity balance was performed in Fatnassa, a representative Saharan oasis in Tunisia. Two spatial levels were monitored over a period of two years: an irrigated and drained field (0.8 ha) and the northern part of the oasis covering 114 ha. Results showed an equilibrated salinity balance at the field level, whereas, at the oasis level, the drainage system was unable to evacuate more than 30% of the salts in the first year and 15% in the second. We consider the clogging effect detected in several locations in the oasis as the main cause of this dysfunction. For the future, we recommend a more participatory approach to designing drainage systems, probably moving toward mixed systems with traditional open ditches and modern subsurface pipes, both easy to maintain by the farmers themselves. Adequate envelopes to prevent clogging in mineral soils have to be tested in situ before extension of subsurface drainage. Copyright © 2013 John Wiley & Sons, Ltd.

Collection and evaluation of lucerne (Medicago sativa L.) germplasm from oases of Tunisia

Lucerne (Medicago sativa) is the most important fodder crop in the oases of Tunisia. A total of 20 accessions from representative of ‘Gabssia’ landraces were collected during the growing season of 2004 and evaluated ex situ at IRA experimental fields of Medenine in the figure (Collecting sites of local lucerne and IRA’s experimental field). Landrace populations grown by the farmers were mixture of several types. Considerable variation was observed for all the characters studied according to the descriptors published by CEC & IBPGR (Commission of the European Communities & International Board for Plant Genetic Resources (1984) Forage legume descriptors, AGPG: IBPGR/84/191, ISBN 90 6605 022 5, 25 pp). Analysis of variance (ANOVA) was performed to compare variation between the different landraces. The differences are highly significant (α = 0.05) for the most studied characters. The least significant difference (LSD0.05) was also calculated to assess differences between accessions. For most variables, in particular yield, a significant difference was obtained between accessions. It was found that forage yield of lucerne germplasm from oases is variable and breeding program should be developed.

Genetic diversity in ecotypes of Tunisian date-palm (Phoenix dactylifera L.) assessed by AFLP markers

SummaryAmplified fragment length polymorphisms (AFLP) were used successfully to survey genetic diversity in 40 ecotypes of date-palm (Phoenix dactylifera L.) collected from oases in Tunisia. Six primer pairs were screened to assess their ability to detect polymorphism in this tree crop. As a result, a total of 428 AFLPs have been generated and used to estimate genetic distances which ranged from 0.07 – 0.63. A large, and typically continuous, range of genetic diversity characterises Tunisian date-palm germplasm. In addition, the UPGMA dendrogram derived from these data exhibited two clusterings of ecotypes independent of their geographic origin or the sex of the trees. These data corroborate the hypothesis of the origin of date-palm domestication being in Mesopotamia. Moreover, taking into account the high percentage of polymorphic bands, together with their resolving power (Rp), all the primer pairs tested contributed to the discrimination of date-palm genotypes, suggesting that the AFLP method is efficient in assessing genetic diversity in this crop. The data are discussed in relation to the use of AFLP molecular markers in the management and improvement of date-palm.

Geothermal resource development in agriculture in Kebili region, Southern Tunisia

Geothermal energy in the Kebili region, south of Tunisia, is used in a number of applications, but mainly in agriculture. Approximately 95% of the thermal water is used for irrigation of oases and heating greenhouses. Generally, when the water temperature is less than 40–45 °C it is used directly for irrigation, but when it exceeds 45 °C it is cooled by means of atmospheric towers before being used to irrigate 16,000 hectares of oases (half of the total area of the oases in Tunisia). Geothermal energy is also used for heating and irrigating greenhouses, which are considered promising and economically feasible applications. The total area of heated greenhouses in the country has increased considerably and is today at 103 ha, 44% of which are located in the Kebili area. Utilization of the geothermal resources will, without a doubt, increase in the near future once we have implemented the last phase of the greenhouse project. By the end of 2003, 13 ha will be added in the region, representing an increase of 29%.

Descriptions of Cervidellus Serratus (Thorne, 1925) Thorne, 1937 From Sweden and C. Neftasiensis N. Sp. From Tunisia, With a Note On Some Recently Proposed Genera (Nematoda: Cephalobidae)

Cervidellus serratus is described from specimens obtained from arable land in Sweden. Light and scanning electron microscope studies provide additional information on cephalic and labial organisation, and general morphology of the male. C. serratus and C. serricephalus are proposed as synonyms. C. neftasiensis n. sp. is described from specimens obtained from an oasis in Tunisia. The new species is distinguished from other species of Cervidellus by its small size. The relationships of Cervidellus to some genera, Acrobelophis, Ypsylonellus and Stegelletina, recently proposed by Andrassy are discussed.