Institute Superieur Agronomique Of Chott Meriem Isa Cm

Tunisia

Institute Superieur Agronomique Of Chott Meriem Isa Cm

Tunisia

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Harbi A.,Institute Superieur Agronomique Of Chott Meriem Isa Cm | Harbi A.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Beitia F.J.,Instituto Valenciano Of Investigaciones Agrarias Ivia | Tur C.,Transformaciones Agrarias SA TRAGSA | And 3 more authors.
Acta Horticulturae | Year: 2015

The endoparasitoid Diachasmimorpha longicaudata (Ahsmed) (Hymenptera: Braconidae) is one of the larval parasitoids used in biological control of Tephritid fruit flies. Ceratitis capitata (Diptera: Tephritidae) is an economically important fruit fly of special importance in Spain, and mainly in the Valencia Community by the economic importance of the citrus sector. Nowadays the control of C. capitata in Valencia is based on the integration of area-wide Sterile Insect Technique (SIT) program with pest monitoring, mass trapping and chemical applications. The biological control of C. capitata is under study, for this reason in 2009 the larval parasitoid D. longicaudata was imported from Mexico. A release study is presented here to determine its contribution to medfly control. Different densities of D. longicaudata adults were released once each season in a citrus plot to determine its dispersion on the plot and the parasitism rate exerted in infested sentinel apples. The results showed that the parasitoid D. longicaudata is able to disperse and parasitize C. capitata larvae in Mediterranean climatic conditions.


Marzougui S.,CNRS Hydrology and Geochemistry Laboratory of Strasbourg | Schafer G.,CNRS Hydrology and Geochemistry Laboratory of Strasbourg | Dridi L.,Institute Superieur Agronomique Of Chott Meriem Isa Cm
Water, Air, and Soil Pollution | Year: 2012

This study focuses on a detailed analysis of the errors introduced by two quasi-analytical approaches based on either Fick's first law or a combination of Fick's and Darcy's laws to evaluate the vapour flux of chlorinated solvents from a source zone located in the unsaturated zone towards the atmosphere. A coupled one-dimensional numerical flow and transport model was developed and applied to three case studies characterised by different water content profiles in the vadose zone and under different levels of maximum dense nonaqueous-phase liquid vapour concentrations and vapour pressure conditions of the source zone. The steady-state concentration and pressure profiles obtained were then used in the two quasi-analytical approaches to estimate the flux towards the atmosphere. When mass fluxes due to density-driven advection become dominant and the vertical advective mass fluxes are increased due to strong pressure gradients in the soil air, the error was observed to increase when using the pure diffusion approach in the quantification of the surface flux calculated by the numerical model with increasing dimensionless Rayleigh numbers. Without taking into account the advective transport in the approach, the relative error calculated with only Fick's law overestimates the real vapour flux when density-driven advection is dominant and underestimates it when pressure-gradient-driven advection dominates. The more advanced advective-diffusive quasi-analytical approach fits reasonably well with the numerically obtained mass fluxes except near soil layer discontinuities, where the evaluation of both the concentration gradient and pressure gradient in the porous media as well as the determination of the average effective diffusion coefficients are rendered more difficult. © Springer Science+Business Media B.V. 2012.


Boughalleb F.,Institute Superieur Agronomique Of Chott Meriem Isa Cm | Hajlaoui H.,Institute National Of Recherche En Genie Rural
Acta Physiologiae Plantarum | Year: 2011

Photosynthetic gas exchange, vegetative growth, water relations and fluorescence parameters as well as leaf anatomical characteristics were investigated on young plants of two Olea europaea L. cultivars (Chemlali and Zalmati), submitted to contrasting water availability regimes. Two-year-old olive trees, grown in pots in greenhouse, were not watered for 2 months. Relative growth rate (RGR), leaf water potential (ΨLW) and the leaf relative water content (LWC) of the two cultivars decreased with increasing water stress. Zalmati showed higher values of RGR and LWC and lower decreased values of ΨLW than Chemlali, in response to water deficit, particularly during severe drought stress. Water stress also caused a marked decline on photosynthetic capacity and chlorophyll fluorescence. The net photosynthetic rate, stomatal conductance, transpiration rate, the maximal photochemical efficiency of PSII (Fv/Fm) and the intrinsic efficiency of open PSII reaction centres (F′v/F′m) decreased as drought stress developed. In addition, drought conditions, reduced leaf chlorophyll and carotenoids contents especially at severe water stress. However, Zalmati plants were the less affected when compared with Chemlali. In both cultivars, stomatal control was the major factor affecting photosynthesis under moderate drought stress. At severe drought-stress levels, the non-stomatal component of photosynthesis is inhibited and inactivation of the photosystem II occurs. Leaf anatomical parameters show that drought stress resulted in an increase of the upper epidermis and palisade mesophyll thickness as well as an increase of the stomata and trichomes density. These changes were more characteristic in cv. 'Zalmati'. Zalmati leaves also revealed lower specific leaf area and had higher density of foliar tissue. From the behaviour of Zalmati plants, with a smaller reduction in relative growth rate, net assimilation rate and chlorophyll fluorescence parameters, and with a thicker palisade parenchyma, and a higher stomatal and trichome density, we consider this cultivar more drought-tolerant than cv. Chemlali and therefore, very promising for cultivation in arid areas. © 2010 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.


Elimem M.,Institute Superieur Agronomique Of Chott Meriem Isa Cm | Chermiti B.,Institute Superieur Agronomique Of Chott Meriem Isa Cm
Floriculture and Ornamental Biotechnology | Year: 2013

A study of the preferential choice of Frankliniella occidentalis Pergande revealed the presence of a phototropism of this pest towards the petal color of its host plant. The color of roses may influence infestation rates by Western Flower thrips. The white-cream rose variety 'Ociane' attracted more individuals of F. occidentalis than the red variety 'First-red' in the same greenhouse; 29.54 and 39.85 thrips/flower on 'Ociane' while only 12.40 and 29.59 thrips/flower recorded on 'First-red' on May 31st and June 14 th 2007, respectively. In fact, those differences were highly significant almost throughout the entire study period. The predatory bug Orius sp. also showed a similar preference for the 'Ociane' than 'First-red', and thus followed the distribution of its prey. © 2013 Global Science Books.

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