SALMA KLOULA BEN GHORBAL¹

LOBNA MAALEJ¹

AHMED LANDOULSI²

ABDENNACEUR HASAN¹

MONCEF FEKI ³

ABDELWAHEB CHATTI¹

¹Laboratoire de Traitement et Valorisation de Rejets Hydriques, Centre des Recherches et des Technologies des Eaux (CERTE), Technopole Borj Cédria, BP 273- Soliman 8020. Université de Carthage. Tel: 216 79 325 199 Fax: 216 79 325 802.

²Unité de Biochimie des Lipides et interaction des macromolécules en Biologie, 03/UR/0902. Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences de Bizerte, Zarzouna. ; Université de Carthage. 7021. Tel: 216 72 591845. Fax: 216 72 590566.

³Laboratoire de biochimie, Hôpital La Rabta, Tunis, Tunisia

Abstract –: Depending on the age of the inoculums for swarming, Pseudomonas aeruginosa undergoes a multicellular behavior called swarming which seems to be closely related to the age of the inoculums and therefore to the fatty acid profile of the membrane of swarmer cells.

- This study was conducted to investigate the role of fatty acids in regulation of swarming motility in Ps.aeruginosa.

- We identified the fatty acid composition in swarmer cells of Ps. aeruginosa, from inoculums at different stages of growth. Preculture of four inoculums were stopped at different times corresponding to the point of log, exponential, early stationary and late stationary phases. Then, these inoculums were used for swarming assay. In parallel, we analyzed the membrane composition of swarmer cells, scarped from the edge of the swarm zone, to investigate the possible role of fatty acids in regulation of swarming in Ps. aeruginosa.

- Here, we report that it is possible that endogenously fatty acids can be released from phospholipids of the membrane and could act as intracellular signals to regulate swarming in Ps. aeruginosa.

- Together, these data suggest an hypothetic correlation between physical state of the membrane lipid bilayer and swarming phenotype of Ps. aeruginosa.

Keywords: Phospholipids, Malondialdehyde, Ps. aeruginosa, swarming, growth

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NESRINE KADRI ¹

HAMOUDA AICHI ²

NACEUR MAHDHI ³

¹ National Agronomic Institute of Tunisia, University of Carthage Tunisia

² Higher School of Agriculture of Mograne, Zaghouan, University of Carthage Tunisia

³Institute of Arid Regions, Medenine, Tunisia

Abstract – In arid area, rainfed agriculture is one of the most vulnerable system to climate change. Stabilizing smallholder crop yields under changing climatic conditions will require adaptation of strategies focused on soil and water management. In Oum Zessar watershed (South-East Tunisia), Rain Water Harvesting (RWH) techniques is one of the adaptation strategies that has been adopted by farmers. At the scale of this watershed, we aimed to identify the current and potential RWH techniques. Then, to analyze the socio-economic and ecological determinants of their adoption by farmer’s and finally to evaluate and prioritize these techniques. Our approach was based on a comprehensive multi-criteria analysis method performed on data gathered with the help of a socio-economic surveys. Results show that age, gender, importance of the technology, education level, residence, household size, agricultural activity, exploitation size, farmer’s income, structure cost, slope and erosion are the most socio-economic and ecological determinants of adoption of RWH techniques. Furthermore, the study found that in the three watershed compartments (upstream, middle stream and downstream), Tabias, Mejels and Fesguias are the top priority RWH techniques. In contrary, buried stone pockets are suitable in the upstream and downstream compartments and mountain spillways are appropriate at middle stream areas.

Keywords: Rainfed agriculture, RWH techniques, multicriteria analysis, determinants of adoption, assessment and prioritization.

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CHARLES MUANDA ⁽¹⁾

ISSAM DAGHARI ⁽²⁾

FATMA BADER ABUAZIZA ⁽³⁾ 

HEDI DAGHARI ⁽²⁾

¹ INBTP, 21, Avenue de la montagne, Ngaliema, Kinshasa, Democratic Republic of Congo

²Agronomic National Institute of Tunisia, 43 Avenue Charles Nicole, 1082, Tunis, Green-team laboratory, University of Carthage, Tunisia

³Benghazi University, Benghazi, Libya

Abstract – Water blending is one of the most common strategies to improve the overall water supply and water quality.

The Hydrus-1D model has been applied in the following treatments:

- Full blending between saline water (1 g/l or 3 g/l or 5 g/l) and distilled water before water supply,

- An alternating supply between saline water (1 g/l or 3 g/l or 5 g/l) and distilled water with the same proportions (50% of saline water and 50% of distilled water), i.e. every day (T50-50), either day by day (T1d-1d), or two days by two days (T2d-2d).

The same daily amount of blended water was supplied in all cases. Two time-cycle in modelling were considered, the first 48 hours of crops cycle and a complete crop season wish is about 90 days. Based on Hydrus-1D modelling, the interval between the desalinated water and saline water intake must be reduced. The longer the interval between salt water inflow and freshwater inflow, the higher the observed salinity peak is. The highest salinity was observed successively in the cases of T2d-2d, followed by T1d-1d and then by T50-50. Full blending leads to the lowest salinity, it is the recommended treatment. These results are in concordance with field trials. Saline water and desalinated water blending is less profitable than fresh water in the case of moderately saline-sensitive crops such lettuce due to high desalinated water cost.

Keywords: water blending feasibility, irrigation scheduling with blended water, Hydrus 1-D, soil profiles salinities

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