Distribution des types sexuels dans une population de Zymoseptoria tritici collectée du blé tendre dans la région d’El Haouaria

R. BELHADJ CHEDLI^1,4

L. AOUINI ²

S. BEN M’BAREK^3,4

A. YAHYAOUI^4,5

S. REZGUI¹

H. CHAABÈNE¹

¹ National Agronomic Institute of Tunisia (INAT), 43 Avenue Charles Nicolle, 1002 Tunis, Tunisia.

² Department of Agronomy, Purdue University, 915 West State Street, West Lafayette, IN 47907

³ Regional Field Crops Research Center of Beja (CRRGC) BP 350, 9000 Beja, Tunisia.

⁴ CRP Wheat Septoria Phenotyping Platform, Tunisia.

⁵ Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT), km 45 Carretera México-Veracruz El Batán, Texcoco.

Abstract – Bread wheat is one of the most important cereal crop in Tunisia, nonetheless production is highly affected by drought and diseases mainly Septoria tritici blotch (STB) caused by the fungus Zymoseptoria tritici. The main objective of this study is to assess the mating types distribution of 103 bread-wheat-derived Z. tritici isolates collected during 2015-2016 cropping season from El Haouaria region where STB occurs annually on a bread wheat landrace that is called by farmers ‘Farina Arbi’. For this study, a multiplex PCR was conducted using two pairs of mating type-specific primers for MAT1-1 and MAT1-2. The results showed that on average both mating types occurred with an equal frequency of MAT1-1 and MAT1-2 (44.7% and 55.3% respectively), except for one field where the MAT1-2 was predominant with 74%, which could be certainly related to the reduced population size in this field. Overall, the equal mating type distribution observed at El Haouaria region suggests a frequent sexual reproduction of bread-wheat derived Z. tritici isolates in Tunisia.

Keywords: Farina Arbi, Septoria, sexual reproduction

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I. HEMISSI¹

R. HAMMAMI¹

A. HACHANA¹

H. ARFAOUI¹

B. SIFI¹

¹ National Institute for Agricultural Research, Laboratory of Agricultural Science and Technology, Av. Hédi Karray 2080 Ariana, Tunis, Tunisia.

Abstract – The search for microorganisms that improve soil fertility and enhance plant nutrition has continued to attract attention due to the increasing cost of fertilizers and some of their negative environmental impacts. Acquisition of nutrients by plants is primarily dependent on root growth and bioavailability of nutrients in the rooting medium. Most of the beneficial bacteria enhance root growth, but their effectiveness could be influenced by the nutrient status around the roots. In this study we aimed to investigate the effects of plant-growth-promoting rhizobacteria (PGPR) on durum wheat variety. To achieve this goal, the inoculation of durum wheat seeds by Mesorhizobium strains carried out in order to assess the positive impact of PGPR on growth, nutrientuptake and grain yield under different conditions of N fertilization (at 0%, 25%, 50%, 75%, and 100% of recommended doses). Results of field trials revealed that the efficacy of these strains for improving growth and yield of wheat reduced with the increasing rates of N added to the soil. In most of the cases, significant negative linear correlations were recorded between percentage increases in growth and yield parameters of wheat caused by inoculation and increasing levels of applied N fertilizers. It is highly likely that under low fertilizer application, the inoculation of wheat durum seeds by Mesorhizobium strain might have caused reduction in the synthesis of stress (nutrient)-induced inhibitory levels of ethylene in the roots through ACC hydrolysis into NH₃. The results showed also a synergetic effect of Mesorhizobium strain on nutrient uptake in wheat plant. The results of this study imply that these Mesorhizobium strains could be employed in combination with appropriate doses of fertilizers for better plant growth, better nutrient uptake and savings of fertilizers. The PGPR-based inoculants can be used as components of integrated nutrient management strategies.

Keywords: durum wheat, Mesorhizobium, PGPR, nutrient uptake, Nitrogen

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S. BEN JEMAA¹

S. KDIDI²

M. BOUSSAHA³

E. REBOURS³

M. H. YAHYAOUI²

¹ Laboratory of animal and forage production, National Institute of Agronomic Research of Tunisia, University of carthage, Rue Hédi Karray, Ariana, 2049, Tunisia.

² Livestock and Wildlife Laboratory, Arid Lands Institute, Route Djorf Km 22, 4119 Medenine, Tunisia

³ GABI, INRA, AgroParisTech, University of Paris Saclay, 78350 Jouy-en-Josas, France.

Abstract – D’man sheep is a minority breed in Tunisia that was established nearly two decades ago from a small Moroccan flock. Tunisian D’man is an isolated population which has experienced no gene flow since its introduction. Currently, this population is suffering from an increased incidence of stillbirths and recurrent abortions caused by inbreeding. The availability of dense SNP markers has facilitated the quantification of genomic inbreeding in farm animals. The aim of the present study was to estimate the kinship between the six D’man rams of a Tunisian breeding station and to assess their genomic structure using the Illumina OvineSNP50 BeadChip and comparisons with the French Lacaune and the Tunisian west thin tail breeds. We found moderate to high levels of inbreeding between the old rams ranging from 0.0069 to 0.1202 and low level of genetic diversity (expected heterozygosity ~ 0.26). Substantial level of west thin tail introgression was detected in the young D’man rams although these were supposed to be purebred. Analysis of runs of homozygosity (ROHs) showed that all individuals had at least one ROH > 10 Mb. ROH islands identified within the D’man rams harbored genes whose mutation leads to stillbirth, dystocia, embryo quality reduction and fleece phenotype variation. Our study demonstrates the usefulness of molecular markers in the management of inbreeding in small isolated populations and would be very helpful in the implementation of planned mating scheme based on sire genotypes.

Keywords: D’man sheep, Inbreeding, Single nucleotide polymorphism, Runs of homozygosity.

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S. BEN CHAABAN¹

K. MAHJOUBI¹

¹ Regional Research Centre of Oasis Agriculture, Degache, Tunisia

Abstract – In Tunisia, the carob moth, Ectomyelois ceratoniae is considered as the main pest of dates and pomegranates. The purpose of this study is to evaluate the efficacy of the mass trapping pheromone combined with Trichogramma cacoeciae release to control the the carob moth populations. Field experiments were conducted in 2018 in three oases located in the south of Tunisia. The efficacy of the treatment was evaluated by assessing male captures in traps and percentage of fruit infestation. Results showed that the highest numbers of carob moth adults were captured in untreated oases compared with the control plots. The treatment provided 72.9 and 52.8% reduction of insect captures respectively on date palm and on pomegranate in Tayfout oasis. In Hazoua and Rjim Maatoug oases the capture reductions were 78.6% % and46% respectively. Dates infestation was highest in the control plots (15%, 10% and 7.2 %) respectively in Tayfout, Rjim Maatoug and Hazoua oases compared with treated plots (3.2, 3 and 2.3%). Regarding pomegranate, rate of fruit damage was significantly lower in the treated oasis compared to the control oasis.

Keywords: Ectomyelois ceratoniae, mass trapping, Trichogramma cacoecae, date palm, pomegranate

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A. MGUIDICHE¹

B. DOUH²

G. PROVENZANO³

A. BOUJELBENE²

¹ Olive Institute

² Higher Institute of Agronomy of Chott Meriem Tunisia

³ University of Palermo

Abstract – In Tunisia, the amount of water for irrigated agriculture is higher than about 80% of the total resource. The increasing population and the rising food demand, associated to the negative effects of climate change, make it crucial to adopt strategies aiming to improve water use efficiency (WUE). Moreover, the absence of an effective public policy for water management amplifies the imbalance between water supply and its demand. Despite improved irrigation technologies can enhance the efficiency of water distribution systems, to achieve environmental goals it is also necessary to identify on-farm management strategies accounting for actual crop. In this paper the suitability of the HYDRUS-2D model to simulate volumetric soil water content in the root zone of a potato crop under subsurface drip irrigation (SDI) is initially assessed on the basis of a field study. Then, considering that the potato crop is moderately sensitive to soil salinity, the model is tested to predict the salt water requirement.

Keywords: HYDRUS-2D, efficiency, volumetric soil water, salinity

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