Identification and partial characterization of antifungal and antibacterial activities of two Bacillus sp. strains isolated from salt soil in Tunisia

Two Bacillus sp. strains (B29 and B27) isolated from soil in the South of Tunisia were tested for their abilities to produce antimicrobial compounds. Both strains showed antimicrobial activity against Gram-positive and Gram-negative bacteria, yeasts and fungi. The produced compounds were extracted by using four different solvents. The hexane solvent allowed to obtain maximum of activity of the strain B29. The activity of the strain B27 was not elucidated by the four solvents used. Bio-autography results of B29 hexane extract revealed presence of different antibiotics and antifungal compounds with different Rf values of 0.3 and 0.76 for antifungal compounds and of 0.12, 0.14, 0.19 and 0.3 for antibacterial ones. Two active fractions were isolated from the culture broth of the strain B29 by semi-preparative high performance liquid chromatography (HPLC). The partial sequencing of the 16S rDNA gene was used to identify the two Bacillus strains. They may be assigned to new Bacillus specie

Literature review on Water Productivity of date palm trees in Tunisian agro systems

The sustainability of agricultural productivity is closely related to the optimal exploitation of natural resources, namely the efficient water resources management.  The evaluation of the effectiveness of the adopted strategies and the applied practices and systems relies on a number of criteria and parameters of which water productivity indices represent the most relevant criteria. In this context, the present study aims to assess the water productivity for date palm cultivation in Tunisia based on an accurate literature review of the previously published scientific papers and reports related to the different studies carried out in these agro-oases regions of the country for the evaluation of the different indices of water productivity. This review represents the main baseline document highlighting in an exhaustive way the challenging features related to water productivity for date palm agro-systems. The outcome of this review indicates that (i) the cultivated date surface is  expanding, covering more than 58.000 ha with a total production of 355.000 tons in 2021(ii) the distribution of irrigation water is variable and irregular. iii) The reported water supply  for date palm range from 20,000 to 30,000 m3/ha while a number of scientific-based calculations estimate the crop water requirements for regular date palm production is  between 10,000 and 18,000 m3/ha (iv) the efficiency of water conservation techniques is related to numerous in farm factors related to the old traditional surface irrigation systems, to the soil salinization, alkalization and  permeability  loss and to the overexploitation issues of water resources that reaching is growing and may impact the productivity of date palms and sustainability of the production system (v) the estimation of the biophysical water productivity based on the reported data reaching barely  0.66kg/m3. This overview highlights the need for an accurate evaluation of the ecological efficiency of the used management measures to a clear appreciation of the  new strategies and policies to face the current constraints with regard to all different driving forces influencing water productivity both at the macro and micro scale

Chemical fruit composition of Tunisian date palm 'Deglet Nour' collected at maturation from four different oases in Djerid region

peer reviewedThe Deglet Nour in Djerid Region is the most popular variety of date palm. Our study aims to provide information about physicochemical properties of dates Deglet Nour at Tamar stage from different oases in Djerid Region. The date fruits were collected from four different oases at different locations in South Tunisia: Traditional Continental Oasis (TCO), Traditional Mountain Oasis (TMO), Modern Continental Oasis (MCO), and Modern Palm Date Plantation (MPP). Fruit size and weight, Total Soluble Solids (TSS), pH, Titratable Acidity (TA), Dietary Fiber (DF), Protein content (MPT) and sugars were studied. The obtained results showed that physiochemical properties varied significantly according to the locations. Fruits from all oasis may be considered suitable for marketing as Deglet Nour dates from well-known producing areas. TSS, pH, TA, MPT and sugars were significantly important in dates from TMO oasis

Evaluation of Salt Stress-Induced Changes in Polyamine, Amino Acid, and Phytoalexin Profiles in Mature Fruits of Grapevine Cultivars Grown in Tunisian Oases

Salinity stress has become an increasing threat to viticulture in the Tunisian oasis, and more generally, the characterization of salinity tolerance markers can be of great interest for sustainable grape production. This study investigated some metabolic adaptations in different tissues of the ripe berries of indigenous grapevine cultivars after exposure to salt stress to identify the key traits of salt stress tolerance under oasis conditions. We especially focused on the adaptive responses occurring at the level of amino acids, polyamines, and stilbene phytoalexins in the grape berry skin, pulp, and seeds of six grapevine cultivars differing in phenotypic and ampelographic characteristics. Our data showed that amino acids accumulated strongly in the pulp and skin, while resveratrol, trans-piceid and trans-ε-viniferin, as major phytoalexins, significantly accumulated in the seeds. High salinity was also found to increase both the berry skin and pulp contents of essential amino acids such as threonine, valine, leucine, isoleucine, lysine, methionine, and phenylalanine. The amounts of stilbenes also increased under high salinity in the berry skin of all the studied cultivars. Polyamine homeostasis within the different berry tissues suggested enhanced polyamine biosynthesis rather than polyamine oxidation in response to high salinity. Our principal component analysis revealed a clear discrimination between the cultivars based on their metabolic profiles within the ripe berry tissues under high salinity

Literature review on Water Productivity of date palm trees in Tunisian agro systems

The sustainability of agricultural productivity is closely related to the optimal exploitation of natural resources, namely the efficient water resources management.  The evaluation of the effectiveness of the adopted strategies and the applied practices and systems relies on a number of criteria and parameters of which water productivity indices represent the most relevant criteria. In this context, the present study aims to assess the water productivity for date palm cultivation in Tunisia based on an accurate literature review of the previously published scientific papers and reports related to the different studies carried out in these agro-oases regions of the country for the evaluation of the different indices of water productivity. This review represents the main baseline document highlighting in an exhaustive way the challenging features related to water productivity for date palm agro-systems. The outcome of this review indicates that (i) the cultivated date surface is  expanding, covering more than 58.000 ha with a total production of 355.000 tons in 2021(ii) the distribution of irrigation water is variable and irregular. iii) The reported water supply  for date palm range from 20,000 to 30,000 m3/ha while a number of scientific-based calculations estimate the crop water requirements for regular date palm production is  between 10,000 and 18,000 m3/ha (iv) the efficiency of water conservation techniques is related to numerous in farm factors related to the old traditional surface irrigation systems, to the soil salinization, alkalization and  permeability  loss and to the overexploitation issues of water resources that reaching is growing and may impact the productivity of date palms and sustainability of the production system (v) the estimation of the biophysical water productivity based on the reported data reaching barely  0.66kg/m3. This overview highlights the need for an accurate evaluation of the ecological efficiency of the used management measures to a clear appreciation of the  new strategies and policies to face the current constraints with regard to all different driving forces influencing water productivity both at the macro and micro scale

A Hot Spot of Olive Biodiversity in the Tunisian Oasis of Degache

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