Institute des Regions Arides

Medenine, Tunisia

Institute des Regions Arides

Medenine, Tunisia
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Gorai M.,Institute Superieur Of Biologie Appliquee Of Medenine | El Aloui W.,Institute des Regions Arides | Yang X.,CAS Institute of Botany | Neffati M.,Institute des Regions Arides
Plant and Soil | Year: 2014

Aims: Seeds of Henophyton deserti (Brassicaceae), an endemic saharan shrub in south Tunisia, produce a pectinaceous mucilage layer that can imbibe a large amount of water when wetted. The aim of this study was to explore the role of mucilage in seed germination of this shrub under heterogeneous stressful environments. Methods: Germination of both intact and demucilaged seeds was tested over wide ranges of temperature, and in iso-osmotic solutions of NaCl and PEG. Recovery of germination after NaCl and Polyethylene Glycol (PEG)-6000 treatment was also tested. The effect of mucilage on water uptake was measured and the structure of the seed investigated. Results: A considerable proportion of seed mass (30 %) is made up of mucilage, which is extremely hydrophilic and able to increase seed mass by 550 % over dry seeds. Mucilage water uptake appears to be unaffected by salt concentration, while higher concentrations of PEG inhibit mucilage hydration. Mucilage decreases germination specifically at 10 °C and this effect can be interpreted in relation to oxygen uptake. High concentrations of NaCl and PEG decrease both germination percentage and rate, with some greater tolerance at 15 °C and 20 °C versus 25 °C. Recovery was higher from higher concentrations of NaCl and PEG and lower temperatures, with a clear inhibitory effect of mucilage. Conclusions: The study has shown that the mucilage of H. deserti may act as a physical barrier for regulating diffusion of water and oxygen to the inner tissue of the seed and thereby prevent germination under unsuitable conditions. © 2013 Springer Science+Business Media Dordrecht.

Gamoun M.,Institute des Regions Arides | Hanchi B.,Faculte des science de Tunis
Arid Ecosystems | Year: 2014

Two treatments were used to evaluate the effect of grazing intensity (continuously grazing and controlled grazing). The schedule is as follows: 1) Rest 3 years (2004 to 2007), 2) Graze 2 months (August and July) 2007, 3) Rest 7 months (September to March) 2007–2008. The grazing impact at the area of 2000 ha was by 1700 sheep and goats during two months, followed by second rest (7 months) maintain resilient rangelands and ensure a sustainable flow of rangelands goods and services to livestock. The control was at grazing system, allows animals unrestricted and uninterrupted access to a grazing unit for all or most of the grazing season. Novelty of this studies is in the new data, which demonstrates that the rest periods allow plants to recover before they are grazed again, and if controlled grazing can avoid overgrazing effects. © 2014, Pleiades Publishing, Ltd.

Agency: European Commission | Branch: FP7 | Program: CP-FP-SICA | Phase: ENV.2010.3.1.1-4 | Award Amount: 2.62M | Year: 2011

WAHARA will take a transdisciplinary approach to develop innovative, locally adapted water harvesting solutions with wider relevance for rainfed Africa. Water harvesting technologies play a key role in bringing about an urgently needed increase in agricultural productivity, and to improve food and water security in rural areas. Water harvesting technologies enhance water buffering capacity, contributing to the resilience of African drylands to climate variability and climate change, as well as to socio-economic changes such as population growth and urbanisation. To ensure the continental relevance of project results, research will concentrate on four geographically dispersed study sites in Tunisia, Burkina Faso, Ethiopia and Zambia, covering diverse socio-economic conditions and a range from arid to sub-humid climates. The project emphasizes: i) participatory technology design, i.e. selecting and adapting technologies that have synergies with existing farming systems and that are preferred by local stakeholders, yet tap from a global repertoire of innovative options; ii) sustainable impact, i.e. technologies that combine multiple uses of water, green and blue water management, and integrated water and nutrient management. Using models, water harvesting systems will be designed for maximum impact without compromising downstream water-users, contributing to sustainable regional development; iii) integration and adaptability, i.e. paying attention to the generic lessons to be learned from local experiences, and developing guidelines on how technologies can be adapted to different conditions; and iv) learning and action, i.e. a strategy will be developed to enable learning and action from successes achieved locally: a. within a region, to upscale from water harvesting technologies to water harvesting systems, and b. across regions, promoting knowledge exchange at continental scale.

Akrout A.,Institute des Regions Arides | Gonzalez L.A.,University of Almeria | El Jani H.,Institute des Regions Arides | Madrid P.C.,University of Almeria
Food and Chemical Toxicology | Year: 2011

The essential oil of Artemisia campestris and the ethanol-water, hexane and water extracts of A. campestris and Thymelaea hirsuta collected in southern of Tunisia were investigated for their antioxidant (DPPH, ABTS and beta-carotene methods) and antitumor growth inhibition of human colon cancer HT-29 cells using MTT test activities. All the A. campestris extracts tested at high concentrations (100 μg/ml) showed activity ranging from 19.5% for essential oil to 64.4% of negative control growth for infusion extract, except the hexane extract. With T. hirsuta, all the extracts tested (hexane and ethanol-water), except the infusion extract, also exhibited antitumor activity (58.2% and 65.5% of control growth respectively). The ethanol-water and infusion extracts of A. campestris showed higher antioxidant activity, polyphenol and flavonoid contents than those of T. hirsuta. These results show that there is a positive correlation between the antitumor activity and the antioxidant activity, and of these two activities and with the levels of polyphenols and flavonoids. The essential oil and the other extracts of A. campestris, which exhibited significant antitumor activity against the HT-29 cells deserve further research into the chemoprevention and treatment of colon cancer. © 2010 Elsevier Ltd.

Belgacem A.O.,Institute des Regions Arides | Tarhouni M.,Institute des Regions Arides | Louhaichi M.,International Center for Agricultural Research in the Dry Areas
Land Degradation and Development | Year: 2013

Ecosystems protected from heavy grazing impacts, such as national parks and refuges, are generally considered to sustain higher plant species diversity and better ecosystem composition and structure compared to heavily grazed areas. To evaluate the impact of livestock grazing, we sampled vegetation characteristics from two areas having different grazing intensity levels. The first site has high protection from grazing and is located inside the Bou Hedma National Park in Southern Tunisia. The second site has a low protection from grazing and is situated within an open area located immediately outside the park boundary where human populations and their livestock have unrestricted access to ecosystem resources. Total plant cover, density, perennial species cover and their contribution were compared between the two grazing level sites. Results show that considerable positive effects occur in the areas protected from grazing. As compared to the overgrazed (open) sites. Several species known for their high palatability, such as Cenchrus ciliaris L., Salvia aegyptiaca L., Echiochilon fruticosum Desf. and Helianthemum sessiliflorum Desf., are more abundant inside the park than outside. These results are very important for managers to apply this technique as a tool for increasing the resilience of arid ecosystems, qualified very vulnerable to climate change. © 2011 John Wiley & Sons, Ltd.

The oil extraction process from olive fruits produces a large quantity of liquid waste, so called as olive oil mill wastewaters "Margines" which has a very strong polluting power resulting in high levels of COD (Chemical Oxygen demand) high salinity and a strong phenolic compounds causing environmental pollution. The exploitation of this waste without preliminary treatment is very limited considering its toxicity for soils and plants. In addition, the richness of this effluent in organic compounds and especially on potassic element represents an asset for its agronomic valorization as a fertilizer. This alternative could be regarded as promising if it is practiced in a rational way. It is within this framework that this work has been carried out aiming to study the effect of olive oil mill waste waters spreading on the quantitative and qualitative performance of Barley crop. For developing this work, a randomized complete block design was installed with four amounts of Margines equivalent at 0 m3/ha (T0), 50 m3/ha (T1), 100 m3/ha (T2) and 200 m3/ha (T3), two varieties of barley Arthaoui (local variety) and Pakestani (introduced variety) and 4 replications. The results show a highly significant reduction as well as of the tiller and ears number for the two varieties compared to the control according to the increase of OMWW concentrations. However, the behavior of crop under this effluent presents variability among the two varieties. In addition, the highest amounts either T2 (100 m3/ha) and T3 (200 m3/ha) respectively 100 m3/ha and 200m3/ha recorded a highly significant reduction compared to the control of different yield components such as the number of ears/m2, weight of 1000 seed, the dry matter and seed yield. Although, this reduction was observed but it was less accentuated for the treatment with an amount of 50 m3/ha compared to the other rates.

Salah M.B.,Institute des Regions Arides
Acta Horticulturae | Year: 2013

Farming operations have a direct effect on the date palm production and fruit quality. Research programs conducted in Tunisia and elsewhere helped to solve many problems and adopting new technologies to improve date palm cultivation and protection. Other techniques were also developed for molecular characterization and varietal distinction. The results were obtained in propagation, pollination, fruit thinning, pruning, harvesting and conservation of the pollen and improvement of the date sector in general. Efforts have been made in chemical and biological control of major pests and diseases of date palm, and some successes were realized. This paper reviews the situation of the research work in date palm cultivation and presents major results obtained during the last years. © ISHS 2013.

Maraghni M.,Institute des Regions Arides | Gorai M.,Institute des Regions Arides | Neffati M.,Institute des Regions Arides
South African Journal of Botany | Year: 2010

Ziziphus lotus (L.) Lam. is a deciduous shrub with intricately branched stems in the Rhamnaceae family. It's a dominant and economically important species widely distributed in active sand dunes in the southern desert of Tunisia. To provide basic information for its conservation and reintroduction, we studied the influence of environmental factors on seed germination patterns. The germination responses of seeds were determined over a wide range of constant temperatures (10-50 °C), polyethylene glycol (PEG)-6000 solutions of different osmotic potentials (0 to - 1. MPa) and burial depths (1-10 cm). Temperatures between 15 and 45 °C seem to be favorable for the germination of this species. Germination was inhibited by either an increase or decrease in temperature from the most suitable temperature found (35 °C). The highest germination percentages (100%) were obtained under control conditions without PEG, and increasing moisture stress progressively inhibited seed germination, which was less than 5% at - 1. MPa. When tested for germination in distilled water, after PEG treatments, seeds germinated to the same extent as when fresh. When seeds buried deeply, there was a significant decrease in seedling emergence percentage and rate. Seedlings of Z. lotus emerged well at depths of 1-2 cm and could not emerge when sand burial depth was > 4 cm. © 2010 Elsevier B.V.

Gorai M.,Institute des Regions Arides | Ennajeh M.,Laboratoire des Biotechnologies Vegetales Appliquees a lAmelioration des Cultures | Khemira H.,Laboratoire des Biotechnologies Vegetales Appliquees a lAmelioration des Cultures | Neffati M.,Institute des Regions Arides
Acta Physiologiae Plantarum | Year: 2011

The aim of this study was to investigate the effects of NaCl-salinity on the physiological attributes in common reed, Phragmites australis (Cav.) Trin. ex Steudel. Plants grew optimally under salinity treatment with standard nutrient solution without added salt and at NaCl concentrations up to 100 mM. Applied for 21 days, NaCl-salinity (300 and 500 mM) caused a significant reduction in growth allocation of all different tissues of P. australis. Shoot growth of reed plants displayed a highly significant correlation with plant-water relations and photosynthetic parameters. The net photosynthetic rate and stomatal conductance of reed plants treated with NaCl-salinity at varying osmotic potential (ψπ) of nutrient solutions were positively correlated, and the former variable also had a strong positive relationship with transpiration rate. Leaf water potential and ψπ followed similar trends and declined significantly as ψπ of watering solutions was lowered. The increase in total inorganic nutrients resulting from increased Na+ and Cl- in all tissues and K+, Ca2+ and Mg2+ concentrations were maintained even at the most extreme salt concentration. Common reed exhibited high K+/Na+ and Ca2+/Na+ selectivity ratios over a wide range of salinities under NaCl-salinity. These findings suggest that reed plants were able to adapt well to high salinities by lowering their leaf ψπ and the adjustment of osmotically active solutes in the leaves. © 2010 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.

Gorai M.,Institute des Regions Arides | Neffati M.,Institute des Regions Arides
Acta Physiologiae Plantarum | Year: 2011

Reaumuria vermiculata (L.), a perennial dwarf shrub in the family of Tamaricaceae, is a salt-secreting xero-halophyte found widely in arid areas of Tunisia. In the present study, physiological attributes of R. vermiculata were investigated under salt stress. Four-month-old plants were subjected to various salinity levels (0, 100, 200, 300, 400 or 600 mM NaCl) for 30 days under greenhouse conditions. Results showed that plants grew optimally when treated with standard nutrient solution without NaCl supply. However, increasing osmolality of nutrient solutions caused a significant reduction in biomass production and relative growth rate. This reduction was more pronounced in roots than in shoots. In addition, this species was able to maintain its shoot water content at 30% of the control even when subjected to the highest salt level, whereas root water content seemed to be unaffected by salt. Shoot water potential declined significantly as osmotic potential of watering solutions was lowered and the more negative values were reached at 600 mM NaCl (-3. 4 MPa). Concentrations of Na+ and Cl- in the shoots of R. vermiculata were markedly increased with increasing osmolality of nutrient solutions, whereas concentration of K+ was not affected by NaCl supply. Salt excretion is an efficient mechanism of Na+ exclusion from the shoots of this species exhibiting high K+/Na+ selectivity ratio over a wide range of NaCl salinity. Proline accumulation in shoots was significantly increased with increase in salt level and may play a role in osmoregulation. © 2010 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.

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