Modélisation de l’érosion hydrique par la méthode qualitative PAP/CAR : Cas du bassin versant de Sbaihia, Zaghouan

A. BEN RHOUMA*¹

T HERMASSI²

K.BOUAJILA¹

¹ Institut national agronomique de Tunis, 43 avenue Charles Nicolle, Tunis 1082, Tunisie.

² Institut national de recherche en génie rural eaux et forêts, Rue Hedi Karray Ariana. 2080 Tunisie

Abstract – The Tunisian semi-arid watershed Sbaihia has an agricultural vocation with forest upstream, and despite installing anti-erosion bench system, water erosion still a major problem threatening its ecological balance. This study uses the PAP/CAR model for mapping soil sensibility to water erosion in this watershed, this model uses qualitative decision rules and hierarchical organization of data represented by different thematic maps: vegetation cover, slope and lithology. The results allow us to have qualitative maps showing the potential sensitivity to erosion per unit area. The obtained maps shows that the average erodibility is the main class and that the vegetation cover has an important influence on reducing erosion risks. We have found that the average erodibility class is predominant 67%, and the effect of the vegetation cover in the stabilization of the area is highlighted.

Keywords: Mapping, sensitivity to water erosion, Geographic information system

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Hiérarchisation des origines du phénomène du verdissement précoce des viandes des ovins sacrifiés à l’occasion de l’Aïd El Idha en Tunisie

W. OUESLATI¹*

A. ETTRIQUI¹

S. ZRELLI¹

¹1Laboratory of Food Microbiology, National School of Veterinary Medicine of Sidi Thabet, University Manouba, Tunisia.

Abstract – Our study aims to research and prioritize the origins of the phenomenon of early greening sheep meat sacrificed on the occasion of Eid El Idha in Tunisia. Indeed, following the ritual slaughter of about one million sheep on the day of Eid (September 2017), an alarm has been triggered in our country (same as in Morocco and Algeria) because of the appearance of a green color on the surface and in the depth of the sheep meats immediately after thawing. The 50 meat samples sent to the Laboratory of Food Microbiology of Sidi Thabet (Tunisia) as part of the survey conducted by the General Directorate of Veterinary Services (Competent Authority) presented morphological changes (a greenish color on the surface but much more pronounced in the deep areas of meat and intramuscular spaces associated with a putrid odor and a viscous appearance), physicochemical (high pH> 6) and microbiological (Aerobic Colony Count > 5.10⁵ colony forming units / g, Anaerobes Sulfated Reducing agents> 1.10² colony forming units / g). These modifications led to the conclusion that the early greening of sheep meat sacrificed during Eid El Idha was directly related to a putrefaction phenomenon of bacterial origin. The deep putrefaction was the result of contamination by anaerobic spores of digestive origin (in particular those producing Hydrogen Sulfate (H₂S) which are likely to cause the formation of sulfomyoglobin, derived from the green myoglobin at the origin of deep greening) associated with the superficial putrefaction that was the consequence of bacterial contamination due to poor hygiene during slaughter (certainly dominated by Pseudomonas fluorescens responsible for superficial greening). A rise in muscle pH (> 6) was observed and would likely be due to overwork or stress in ritual slaughter. Our results suggest that this increase in pH would be the triggering factor, no longer inhibiting the proliferation of bacteria of deep contamination of digestive origin, and a warm climate characterizing the summer season in Tunisia, favorable to the proliferation of bacteria of superficial contamination, would be the favoring factor.

Keywords: High pH meat - Greening sheep meat - Putrefaction

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A. OTHMANI^1*

C. BAYOUDH²

JM. AL-KHAYRI³

N. DRIRA⁴

¹ Laboratory of in vitro tissue culture, Regional Center of Oases Agriculture Researches, 2260 Degache, Tunisia

² Regional Research Centre on Horticultural and Organic Agriculture, 4042 Chatt-ariem Sousse, Tunisia

³ Laboratory of Plant Biotechnology, Faculty of Sciences of Sfax, 3018 Sfax, Tunisia

⁴ Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, Al-Hassa 31982, Saudi Arabia

Abstract – For the first time, secondary somatic embryogenesis was investigated as an induced process for scaling up the efficiency of vegetative micropropagation of Tunisian date palm (Phoenix dactylifera L.), cultivar Deglet bey (Mnakher). In the first stage, primary somatic embryos were induced on juvenile leaf explants when cultured on Murashige and Skoog solidified medium (1962) supplemented with 10 mg.l-1 2,4-D and 0.3 mg.l-1 activated charcoal. In the second stage, secondary somatic embryos were occurred on whole parts of primary cotyledonary somatic embryos especially cotyledonary leaves when they were isolated and transferred on MS solidified medium supplemented with 0.1 mg.l-1 2,4-D.Similarly, globular and precotyledonary primary embryos obtained from embryogenic suspension cultures in ½ MS liquid medium supplemented with 2 mg.l-1 2,4-D gave rise to secondary somatic embryos but with the highest rate. Secondary somatic embryos were converted into plantlets when they were transferred on MS medium free of plant growth regulators and successfully acclimated in the greenhouse.

Keywords: Cotyledonary leaves, Date palm, Plantlets, Somatic embryogenesis

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Performance des Calendriers d'irrigation Basés sur un Modèle Agro-météorologique : Cas du blé dur en Conditions Semi-arides et Arides de la Tunisie

B. Ben Nouna ^{1 *} 

M. REZIG ¹

S. KANZARI ¹

¹ Institut National de Recherches en Génie Rural, Eaux et Forêts (INRGREF)

Abstract – This paper presents a simple irrigation scheduling calendars for Durum Wheat. The calendars are intended to promote easy and ready adoption of improved water irrigation management practices by farmers under semi-arid and arid conditions of Tunisia. The calendars are developed using a daily agro-meteorological balance model. This Tool takes into account several: planting dates, soil types, initial fill rate of the available water, application water efficiency of irrigation system, and medium or high water climatic demand. The validation of developed irrigation scheduling calendars in the plot farms was integrated part of this work. The use of such irrigation calendars, allows a significant improvement of yield from 17 to 34%, reduces the irrigation water supplies from 8 to 43% and improves in relevant way the water use efficiency of Durum Wheat.

Keywords: Irrigation scheduling calendars, Water use efficiency, Yield, Durum wheat, Semi-arid, arid conditions.

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Etude des effets des régimes microalgaux (basée sur trois espèces Chaetoceros calcitrans, Isochrysis galbana et Spiruline sp) sur l’accumulation lipidique et la croissance des naissains de la palourde Ruditapes decussatus

S. DRIDI*¹

A. FATHALLI ²

¹ Higher Institute of Peach and Aquaculture of Bizert; Bizert ISPA –PB 15, ERRIMEL 7080 Bizert, Tunisia.

² National Institute of Marine Science and Technology, INSTM La Goulette, 2060, Tunis, Tunisia.

Abstract –The main aim of this work is to compare the effect of three species of microalgae (Chaetoceros calcitrans, Isochrysis galbana and Spirulina sp) on growth of spats of the bivalve Ruditapes decussatus, in order to detect the microalgae that allow better growth and consequently improve breeding conditions for this species. The results obtained showed that the nature of the microalgae species used as a feed influences the accumulation of lipids in the flesh of clam spat differently. Thus Isochrysis galbana allowed having the highest percentage of lipids in the dry flesh of clams after four weeks of conditioning (46.1% DW). The differences in measurements of total weight of the three batches of clams fed with Chaetoceros calcitrans, Isochrysis galbana and Spirulina sp between T0 (start of conditioning) and T4 (4 weeks after conditioning) were respectively 0.17 g, 0.13 g and 0.23 g. Differences between metric measurements registered in T0 and T4 for the three batches of clams fed with Chaetoceros calcitrans, Isochrysis galbanaand Spirulina sp were respectively for width 0.1cm, 0.17 cm and 0.17 cm, for length 0.1 cm, 0.07 cm and 0.08 cm and for thickness 0.08 cm, 0.04 cm and 0.05 cm. This shows that the microalgae Isochrysis galbana allows the largest increase in size and weight for R. decussatus spats during the same period of conditionning then the spats fed with Chaetoceros calcitrans and Spirulina sp (for most measured parameters). These results are confirmed by the correlation index R² determined from allometric regression equations relationships linking the total weight and the width of R. decussatus fed with Chaetoceros calcitrans, Isochrysis galbana and Spirulina sp which were respectively 0,72; 0,92 and 0,93. Thus, we conclude that Isochrysis galbana allow the best growth of R. decussatusspats.

Keywords: Ruditapes decussatus spats, microalgae, conditionning, lipids, fatty acids, growth

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N. SAIDI*¹

R. TALBI²

A. LTIFI¹

S. KOUKI¹

M. EL'HIF¹

W. JENDOUBI¹

H. REJICHI³

A. HAFIANE¹

¹ Laboratory of Water, Membrane and Biotechnologies of Environnement, Centre of Research and Water Technologies (CERTE) Technopark of Borj-Cedria Adress: BP 273; Soliman 8020; Tunisia Tel: +216 79412199 Fax: +216 79412802 GSM: +216 55641366.

²Georesources Laboratory Centre of Research and Water Technologies (CERTE) Technopark of Borj-Cedria Adress: BP 273; Soliman 8020

³Agency for the Protection and Development of the Coast 2, Rue Mohamed Rachid ridha Belvedere 1002 Tunis Tunisia.

Abstract – Nowadays, the problems of rejections constitute an increasingly important danger in the receiving medium. Indeed, water is increasingly affected by organic and mineral contamination and even by the micro-organisms of which some are pathogenic and thus dangerous for the ecosystem. In this context, this study aims to determine the physicochemical characterization (Chemical Oxygen Demand-COD, Total Suspended Solids-TSS, salinity and total nitrogen) and microbiological (mesophilic and thermophilic bacteria, bacteria sensitivity to antibiotics) of the sebkha Ben Ghayadha waters. The results showed COD of 4000 mgO₂/L exceeding the limit fixed by the Tunisian standard TN 106.02 (1989) at 90 mgO₂/L by the Environmental Protection for marine hydrological effluent discharge. However, all the TSS values were under 12 mg/L. Also, total nitrogen (TN) ​​values ranged from 1.9 to 47.8 mg /L,rcorded at a depth of 2,3 and 4 meters, respectively. All the obtained results were consistent with TN 106.02 (1989). The bacteriological analysis based on faecal bacteria counts, showed that all the samples analyzed have loads of fecal bacteria lower than that fixed by TN 106.02 (1989). Bacteria isolated from the waters sebkha showed a high sensitivity to antibiotics suggesting a low virulence.

Keywords: Sebkha, salinity, microbiology, pollution, Ben Ghayadha.

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