Institute Superieur Agronomique Of Chott Mariem

Sousse, Tunisia

Institute Superieur Agronomique Of Chott Mariem

Sousse, Tunisia
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Zouari I.,Institute Superieur Agronomique Of Chott Mariem | Mezghani A.,Institute Of Lolivier | Labidi F.,Institute Of Lolivier
Acta Horticulturae | Year: 2017

Olive phenology is a sensitive indicator of climate change and especially the climatic warming of areas where olives are grown. Flowering occurs after being exposed to chilling and subsequent accumulation. The Mediterranean region is characterized by a changeable climate, especially in spring when temperature varies quickly from year to year. In this context, a study was carried out on local ('Meski' and 'Chemlali') and foreign ('Picholine' and 'Koroneiki') olive cultivars grown in southern Tunisia to calculate the heat requirements for flowering during the period 2008-2012. The aim of the present work is to compare flowering full bloom dates for the different cultivars and to calculate the heat requirement until flowering. Heat units were expressed in growing degree day (GDD). For the GDD accumulation, the results indicated a large inter-annual variation. The GDD began being recorded when the calculations of chilling accumulation were stopped. There were differences in flowering dates among cultivars. During the springs of 2008, 2009 and 2010, 'Chemlali' began blooming on 16 April, just after accumulation of 173.85, 100.7 and 160.65 GDD after the end of chilling respectively. 'Koroneiki' was in full bloom on 12 April in 2010-2011 after accumulation of 133.33 GDD. For the year 2011-2012, 'Meski' entered to bloom on 12 April after accumulation of 182.56 GDD while the other cultivars entered into bloom after receiving heat requirements ranging between 169.45 and 267.6 GDD.

Hajlaoui H.,Institute National Of Recherche En Genie Rural | Ayeb N.E.,University of Monastir | Garrec J.P.,French National Institute for Agricultural Research | Denden M.,Institute Superieur Agronomique Of Chott Mariem
Industrial Crops and Products | Year: 2010

The comparative effects of salt stress on osmotic adjustment and solutes accumulation in relation to root-leaf tissue senescence of two silage maize varieties were examined. Studies were carried out with seedlings of two forage maize varieties (Aristo and Arper) subjected to 0, 34, 68 and 102 mM NaCl for 6 weeks under glasshouse conditions. Osmotic potential (OP), osmotic adjustment (OA) and solutes accumulation were quantified in primary roots and in three leaf stages (young, mature and senescent leaves). Moreover, in order to assess the distribution of proline and glycine betaine during root development, the two components were analyzed at different position from the primary root apex of both varieties. The total dry matter was significantly dropped with increasing salinity and reduction was greater in Aristo than in Arper. Salt stress impact in terms of ionic status was more pronounced in roots than in leaves and in older leaves than younger ones. In this setting, Aristo displayed a more sensitivity than Arper. A close relationship between the age of root-leaf tissue and proline and glycine betaine allocation, as salinity response, was shown. During the stress treatment, the accumulation of the two components was higher in growing regions of roots and in young leaves. While total free amino acids (FAA) and sugars were accumulated in roots as well as leaves but preferentially in the mature leaves. The capacity of OA was greater in young than in mature and/or senescent leaves and the contribution efficiency of organic solutes to this occurrence tended to be higher in Arper than in Aristo. Moreover, glycine betaine and proline appeared to be the main solutes that contributed ably to OA mainly in growing regions followed by sugars and other FAA. Inorganic solutes (K+ and Ca2+), however, did not seem to play an important role in OA since their amounts were often reduced in response to salt tolerance. © 2009 Elsevier B.V. All rights reserved.

M'hamdi N.,Institute Superieur Agronomique Of Chott Mariem | Aloulou R.,Institute Superieur Agronomique Of Chott Mariem | Bouallegue M.,University of Tunis | Brar S.K.,INRS - Institute National de la Recherche Scientifique | Hamouda M.B.,Institution Of La Recherche Et Of Lenseignement Superieur Agricole Iresa
Livestock Science | Year: 2010

Records of functional longevity (FL), from first calving to last recording (or culling), of 36,888 Tunisian Holstein cows in 169 herds were studied using survival analysis. Using a Weibull proportional hazard model, the influences of age at first calving, herd-year-season, lactation number-stage of lactation, milk production within the herd and year, annual change in herd size and random genetic effect of sire on FL were studied. Besides a random time-dependent effect of herd-year-season, the model included fixed effects of parity and stage of lactation, within herd and parity production level (all time-dependent), and age at first calving (time-independent). All factors had a significant effect on FL at a level of P< 0.001. Milk yield was by far the most important factor influencing FL and the hazard increased as the milk production decreased. Within the first three lactations, the relative culling risk increased stepwise with lactation stage. The highest risk of culling was found for cows at the beginning and at the end of the first lactation and at the end of any other lactation. The risk of culling decreased with parity. © 2010 Elsevier B.V.

Haouas D.,Institute Superieur Agronomique Of Chott Mariem | Flamini G.,University of Pisa | Ben Halima-Kamel M.,Institute Superieur Agronomique Of Chott Mariem | Ben Hamouda M.H.,Institute Superieur Agronomique Of Chott Mariem
Crop Protection | Year: 2010

The effect of the whole methanol extracts of five Chrysanthemum species on feeding and performance of Spodoptera littoralis (Boisduval) larvae has been investigated in vitro. The extracts exhibited an anti-feeding and phagostimulating activities against cotton leafworm larvae when applied either on leaf discs or incorporated into an artificial diet. Under chosen conditions, the antifeedant index calculated over 24 h for sixth instar larvae significantly varied from 78.55 for Chrysanthemum segetum L. to -44.18 for Chrysanthemum fuscatum Desf. at the dose of 1000 ppm. Toxicity of the extracts was manifested by a high mortality, reduced growth rates, and low weight gain by larvae fed on diets containing 1000-10,000 ppm of the extract. Anyone of the larvae treated with C. hrysanthemum macrotum (D.R.) Ball. leaves crude extract survived to pupation at the two higher concentrations. The time to pupation increased for Chrysanthemum grandiflorum flowers crude extract from 11.40 ± 0.93 to 28.93 ± 10.92 days as the extract concentration in the diet increased from 0 to 10,000 ppm. The ingestion of crude extract by the third instar larvae reduced significantly the consumption, growth and utilisation of the ingested and digested food, and reduced digestibility.The crude extract of the leaves of C. macrotum, dissolved in acetone and topically applied on sixth instar larvae, showed a quite high mortality (95%).These results suggest the presence in the extracts of anti-feeding and/or toxic substances, active by consumption and topical application. The identification of these compounds and their action mode will be object of further studies. © 2010 Elsevier Ltd.

Tlili S.,University of Nantes | Tlili S.,Catholic University of the West | Tlili S.,Institute Superieur Agronomique Of Chott Mariem | Metais I.,University of Nantes | And 4 more authors.
Chemosphere | Year: 2010

Research in ecotoxicology currently focuses to fill the gap existing between sub-organismal responses (e.g. biomarkers) to toxicants and effects occurring at higher levels of biological organisation (e.g. population). The intra-sedimentary bivalve Donax trunculus commonly found in West Atlantic and Mediterranean coasts is a sentinel species useful for biomonitoring studies in sandy beaches. The objective of this work was to link responses at the infra-individual level (core biomarkers as early and sensitive tools) to supra-individual level (population for its ecological relevance). D. trunculus, originating from a polluted site (Radès Méliane) and a comparatively reference site (Sidi Jehmi) in the Gulf of Tunis (Tunisia), were collected bimonthly from November 2008 to October 2009. An increase in catalase activities was usually observed in bivalves from the polluted site compared to the reference site whereas no differences in TBARs were depicted. The anti-oxydant enzyme (catalase) could be able to prevent the deleterious effect on the lipid membranes. Usually GST activities were decreased in the polluted site. Significantly high inhibition in AChE activities in bivalves from the polluted site suggested neurotoxicity disturbances to their in situ exposure to compounds such as organophosphate and carbamates pesticides, heavy metals. Size-distribution of populations of D. trunculus from the polluted Radès Méliane site consisted of four cohorts whereas five cohorts were depicted in the comparatively reference Sidi Jehmi site. The mean total length size and the growth rate of cohorts were significantly reduced in the impacted site compared to the reference site.In conclusion, it may be suggested that disturbances in responses to chemical stress at the infra-individual level could be linked to the responses observed at the population level. © 2010 Elsevier Ltd.

Ben Chaaban S.,Institute Superieur Agronomique Of Chott Mariem | Chermiti B.,Institute Superieur Agronomique Of Chott Mariem | Kreiter S.,Montpellier SupAgro
Bulletin of Insectology | Year: 2011

The old world date mite Oligonychus afrasiaticus (McGregor) (Prostigmata Tetranychidae) is an important spider mite pest of the date palms Phoenix dactylifera L. in most of North Africa and the Middle East. This study was conducted between 2004 and 2006 in an orchard of date palm trees located in southwest Tunisia. The objective of this study was the inventory of mites that revolve around the date palm, to quantify abundance of O. afrasiaticus in trees over different types of ground cover and to document its dispersal. The starting of O. afrasiaticus infestation on fruits varied between years, ranging from the first to the third week of July. Mite populations on pinnae remained low from May through December, not exceeding two mites per pinnae, whereas on fruit they reached peak populations of approximately 14 motile forms of mite per fruit in 2006. Indigenous phytoseiid were not found on fruits between mid-Julys till the end of August, when pest populations peaked. Plants such as Sorghum bicolor (L.) Moench, Solanum melongena L., and Cucumis melo L. contained densities of O. afrasiaticus during early spring, and may have formed the source for later date palm infestation. Fruit bunch infestation was not prevented or even alleviated by glue barriers so infestation of date palm by O. afrasiaticus may occur via aerial dispersal of motile forms. In ground cover phytoseiid and tetranychid mites were scarce, two of tetranychid species are new to science were founded.

Dhillon G.S.,University of Québec | Brar S.K.,University of Québec | Kaur S.,University of Québec | Kaur S.,Banaras Hindu University | And 2 more authors.
Biomass and Bioenergy | Year: 2012

Objectives: The potential of lactoserum as a crude inducer and moistening medium for fungal cellulase and hemicellulase induction was tested through solid-state fermentation. Methodology: Solid-state fermentation was conducted in Erlenmeyer flasks and plastic trays using apple pomace (AP) as solid substrate by Aspergillus niger NRRL 567 and A. niger NRRL 2001. Results: Solid-state tray fermentation resulted in cellulase activities (IU g -1 dry weight basis) of 383.7 ± 17.9, 425.3 ± 21.3, 336.1 ± 16.2 and 4868 ± 39.8, respectively for FPase (filter paper cellulase), CMCase (carboxymethyl cellulase), BGL (β-glucosidase) and xylanase using A. niger NRRL 567. Similarly, A. niger NRRL 2001 resulted in enzyme activities (IU g -1) of 401 ± 23.8, 544.7 ± 24.5, 285.4 ± 11.7 and 4580.7 ± 34.5, respectively for FPase, CMCase, BGL and xylanase. The enzyme loading of FPase 50 IU g -1 substrate in the hydrolysis of AP resulted in (g kg -1): 509.3 ± 22.9 total sugar (48 h), 109.3 ± 5.7 reducing sugar (48 h), 16.1 ± 0.8 glucose (60 h) and 10.4 ± 2.0 xylose, respectively whereas hydrolysis of BSG resulted in (g kg -1): 375.7 ± 16.2 total sugars (36 h), 114.6 ± 4.0 reducing sugar (60 h), 18.1 ± 0.9 glucose (60 h) and 19.8 ± 2.0 xylose (48 h), respectively. Conclusions: This study demonstrated the potential of SSF as a simple and cheap technology for higher cellulase and hemicellulase production using negative cost AP waste which could eventually help to utilize abundant lignocellulosic biomass for production of biofuels and other value-added products. © 2012 Elsevier Ltd.

Hichem H.,Institute National Of Recherche En Genie Rural | El Naceur A.,University of Monastir | Mounir D.,Institute Superieur Agronomique Of Chott Mariem
Photosynthetica | Year: 2010

The effect of four different NaCl concentrations (from 0 to 102 mM NaCl) on seedlings leaves of two corn (Zea mays L.) varieties (Aristo and Arper) was investigated through chlorophyll (Chl) a fluorescence parameters, photosynthesis, stomatal conductance, photosynthetic pigments concentration, tissue hydration and ionic accumulation. Salinity treatments showed a decrease in maximal efficiency of PSII photochemistry (F v/F m) in dark-adapted leaves. Moreover, the actual PSII efficiency (φ PSII), photochemical quenching coefficient (q p), proportion of PSII centers effectively reoxidized, and the fraction of light used in PSII photochemistry (%P) were also dropped with increasing salinity in light-adapted leaves. Reductions in these parameters were greater in Aristo than in Arper. The tissue hydration decreased in salt-treated leaves as did the photosynthesis, stomatal conductance (g s) and photosynthetic pigments concentration essentially at 68 and 102 mM NaCl. In both varieties the reduction of photosynthesis was mainly due to stomatal closure and partially to PSII photoinhibition. The differences between the two varieties indicate that Aristo was more susceptible to salt-stress damage than Arper which revealed a moderate regulation of the leaf ionic accumulation. © Springer Science+Business Media B.V. 2010.

Sdiri S.,Instituto Valenciano Of Investigaciones Agrarias | Navarro P.,Instituto Valenciano Of Investigaciones Agrarias | Monterde A.,Instituto Valenciano Of Investigaciones Agrarias | Benabda J.,Institute Superieur Agronomique Of Chott Mariem | Salvador A.,Instituto Valenciano Of Investigaciones Agrarias
Postharvest Biology and Technology | Year: 2012

In the Mediterranean area, many early-season citrus fruit are regularly submitted to a degreening treatment with ethylene exposure to improve their external color, and afterwards to a cold-quarantine treatment when the fruit is exported to countries free of fruit fly (Ceratitis capitata). Although the effects of the ethylene application on quality attributes as well as bioactive compounds are well documented, there is no information on the effect of the postharvest practices, including the treatment of de-greening followed by the cold-quarantine storage, on the nutritional value of citrus fruit. In this study the changes in bioactive compounds of early-season commercial citrus varieties ('Navelina' oranges and 'Clemenules', 'Clemenpons', 'Oronules', 'Prenules', 'Basol', 'Clemenrubí' and 'Orogros' clementines) submitted to a degreening treatment, without or with ethylene exposure (0μL/L or 2000μL/L C 2H 4, 120h, 21°C, 95% RH) and then cold-stored under quarantine conditions (1°C, 16d) plus shelf-life (20°C, 7d, 95% RH), were determined. These postharvest conditions did not induce detrimental changes in DPPH and FRAP antioxidant capacities, ascorbic acid, total ascorbic acid or total phenolic contents. Although some changes were observed in individual flavonoid compounds, these did not contribute to a loss in the total content of flavanones and flavones after ethylene degreening and the subsequent quarantine treatment. © 2011 Elsevier B.V.

Sdiri S.,Instituto Valenciano Of Investigaciones Agrarias | Navarro P.,Instituto Valenciano Of Investigaciones Agrarias | Monterde A.,Instituto Valenciano Of Investigaciones Agrarias | Benabda J.,Institute Superieur Agronomique Of Chott Mariem | Salvador A.,Instituto Valenciano Of Investigaciones Agrarias
Postharvest Biology and Technology | Year: 2012

In the Mediterranean area, early-season citrus fruit reach acceptable internal maturity standards for marketing, while the fruit are still green. A degreening treatment is widely used as a postharvest practice to improve the external color. Nevertheless, the application of ethylene during this treatment can be associated with calyx senescence. The aim of this study was to evaluate new degreening treatments in order to reduce this disorder. 'Clemenules' mandarins and 'Navelina' oranges, harvested at different external colors, were submitted to different degreening treatments, combining periods with and without ethylene exposure. In both cultivars, the periods without ethylene exposure during degreening reduced the incidence of calyx disorders. To obtain a typical 'Clemenules' variety color with the lowest incidence of calyx alteration, the optimum degreening treatment was based on 72 h with ethylene and 48 h without ethylene when fruit were harvested with a color index of between -9 and -3. On the other hand, a treatment of 24 h with ethylene plus 48 h without ethylene is recommended for fruit with an external color index higher than -2. For 'Navelina' oranges, highly sensitive to calyx senescence during degreening, a treatment consisting of 24 h with ethylene plus 48 h without ethylene is recommended, which involves harvesting the fruit with a color index of over 0. © 2011 Elsevier B.V..

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