Bibliographic Review

A.Najar¹

I. Hamdi¹

K. Ben Mahmoud²

¹ Laboratoire de Protection des Végétaux, Institut National de La Recherche Agronomique de Tunisie, Université de Carthage, Rue Hédi Karray, 1004 El Menzah, Tunisia

² Laboratoire des Sciences et Techniques Agricoles, Institut National de La Recherche Agronomique de Tunisie, Université de Carthage, Rue Hédi Karray, 1004 El Menzah, Tunisia

Abstract – Citrus is one of the most important horticultural crops, with a worldwide fruit production of over 110 million tons per year. The necessity of using rootstocks for citrus fruits is to have a profitable production against some limiting factors such as climate conditions, bad soil conditions and diseases. However, sour orange which the most commonly used rootstock even in the Mediterranean basin has the disadvantage to be highly susceptible to Citrus tristeza virus (CTV), the causal agent of Tristeza disease and strongly limits the use of this rootstock in many citrus growing countries. CTV- tolerant rootstocks have been selected in many citrus growing countries, but in some cases, they exhibited sensitivity to other diseases such as those caused by viroids. Seven viroids reported to infect Citrus spp belong to four genura of the family of Pospiviridae. Surveys have been carried out in many countries and showed that viroids are widespread in commercial citrus plantations, where they are perpetuated with the propagation of infected, symptomless budwood. Several trial fields were conducted under artificial inoculation by different species of viroids to evaluate the performance of some citrus varieties grafted on different rootstocks. The elimination of viroids from infected plants has been a challenging issue and different approaches have been studied to produce viroid-free planting material. Management strategies for viral sanitation involving shoot-tip grafting or somatic embryogenes have been successfully used to eliminate many viroids and virus from plant propagating material. One of essential elements for success to produce virus free propagation material is to implement a rigorous certification program of citrus budwood.

Keywords: Viroids, Characterization, Prevalence, Rootstocks, Certification program.

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F. CHEMAK^1,4

H. MAZHOUD¹

H. ABELHAFIDH²

L. ALBOUCHI²

Y. SNOUSSI³

¹ National Institute for Agricultural Research of Tunisia

² Higher School of Agriculture, Mograne, Tunisia

³ CIHEAM-IAM Saragoza, Espagne

Abstract – Within the context of climate change and increasing water scarcity, the development of irrigated agriculture is required as main lever in order to deal with the food challenges. Tunisia is facing an imminent risk of water shortage given that the policy of the water supply reached its limit while the currently water availability is already below the poverty line (450m³/capita/year).The irrigated agriculture consumes 80% of the water availability and therefore it remains the main sector that might provide water saving for the other sectors. However, the irrigated activities should achieve optimum yields in order to increase production and to meet the population needs. The irrigated cereal crops which account for only 7% of the total cereal area contributed with 25% of the total cereal production. However, the achieved yields are far from the expected potential level. This reveals a crucial question regarding the productivity and the efficient use of the water resources. In order to deal with this issue, field surveys were carried out among a sample of 120 farmers in the governorates of Beja and Siliana by addressing the farming system during the cropping year of 2013-2014. By using two-step nonparametric approach, the optimal production of the durum wheat crop was estimated in order to assess the importance of the production deviation and to identify possible alternatives for improvement. The results showed that the water productivity is under the expected potential given that the average of the sample productivity reached only 8kgha^-1mm^-1. The estimated production frontier suggests that the durum wheat production could be increased by 28% by mastering perfectly the technology process. The results showed also that this improvement is plausible especially among farmers receiving agricultural training. Moreover, farmers might reach better production among large size plots and by practicing suitable crop rotation. 

Keywords: Irrigated activity, technical efficiency, water use efficiency, DEA model, Tobit model.

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Etude de la conservation et de la qualité post – mortem de la crevette rose Parapenaeus longirostris (Lucas, 1846) au cours du stockage réfrigéré

S. DRIDI¹

N. M’HAMDI²

H. M’HAMDI³

¹ Higher Institute of Peach and Aquaculture of Bizert, Bizert ISPA –PB 15, ERRIMEL 7080 Bizert, Tunisia.

² Laboratory of Genetic, Animal and Alimentation Resources, National Agronomic Institute of Tunisia, 43 Avenue Charles Nicolle, 1082 Tunis, Tunisia.

³ Ministry of Agricultutre of Tunisia, CRDA Ben Arous, Tunisia.

Abstract – Pink shrimp Parapenaeus longirostris is a species extensively harvested and marketed in Tunisian local markets and it is a raw material for some food industries. This work consists in studying the evolution of the biochemical and microbiological compositions of the pink shrimp flesh caught in the northern region of Tunisia and landed at the Port of Jarzouna (Bizerte) in March 2017. The analyzes revealed that the pink shrimp flesh at day 8 had a total volatil basic acid (TVBA) content (12.65 mg / 100 g ± 0.56), a trimethylamin (TMA) content (2.57 mg / 100 g ± 0.26) a content of thiobarbituric acid (TBARs ; 4.19 mg MDA / kg ± 0.3), a percentage of lipids (1.49 g / 100 g ± 0.2), a protein content (9.73 g / 100 g ± 0.61), water content (84.58% ± 0.43), ash percentage (1.35% ± 0.04), water activity (Aw ; 0.95 ± 0.001), and coloring which turns to bluish green. The results of the microbiological analyzes showed no contamination in the flesh of pink shrimp during the first three days following sampling and a number of psychrophilic bacteria (200 colony-forming unit (CFU) / g). These values ​​show that the shelf life of the pink shrimp meat remains within the human consumption norms until the 7th day of refrigerated storage.

Keywords: Pink shrimp, refrigerated storage, biochemical analysis, microbiological analyzes, alteration, quality.

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A. THAMEUR¹

B. LACHIHEB²

A. FERCHICHI³

¹ Regional Center of Agricultural Reasearch, B.P 357 Route Gafsa Km 6, Sidi Bouzid 9100. Tunisia.

² Laboratory of Dryland and Oasis Cropping, Institute of Arid Zone of Medenine, ElFjè 4119, Tunisia.

³ National Institute of Agronomy in Tunis. 43, Avenue Charles Nicolle 1082-Tunis- Mahrajène. Tunisia.

Abstract – Five barley genotypes were grown in a growth chamber under well-watered conditions up to early tillering and were then either subjected to water deficit or continually well-watered. Water deficit was induced by withholding irrigation until the field capacity (FC) was 40%, which was then maintained for 90 days. Water deficit improved the water use efficiency (WUE) of four genotypes (Ardhaoui (A), Pakistan (P), Manel (M) and Roho (RO)) by approximately 40%, but caused slight reduction in var. Rihane. High relative water content (RWC) of leaves was maintained in some of the genotypes by stomata closure and a reduction of leaf area. High Net photosynthetic rate under water deficit was associated with high RWC (r=0.51; P<0.05). Decline in Net photosynthetic rate was due mainly to stomata closure (r=0.71; P<0.01). WUE_biomass, WUE_{instantaneouos} and WUE_intrinsic were not directly associated, but WUE_{instantaneous} and carbon isotope discrimination (Δ¹³C) were positively related (r=0.71; P<0.01) while WUE_intrinsic was negatively related (r=-0.58; P<0.05) to intercellular CO₂ concentration (Ci).

Keywords: barley, drought; growth; leaf gas exchange; water use efficiency; carbon isotope discrimination.

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A. BEN RHOUMA¹

T. HERMASSI²

H. HABAIEB²

¹ National agronomy institute of Tunis, 43 Avenue Charles Nicolle, Tunis, 1082 Tunisie

² National institute of Rural, Water and Forest engineering, Rue Hedi Karray 2080 Ariana, Tunisie

Abstract – This study is a research for an effective methodology for water erosion modeling. Indeed, understanding and predicting the effects of this natural phenomenon, is the most difficult for the semi-arid Mediterranean climate due to its climatic irregularity and its soils fragility. USLE model (Universal soil loss equation) estimates soil erosion losses, and makes it easy to decide about what conservation measure we should adopt. USLE was selected because it is the simplest approach while remaining robust, and it solves the problem of data availability. The USLE method is able to simulate the erosive pattern with the possibility of creating several scenarios. For our study case, we found that the majority of the watershed surface shows a low to medium erosion rate, and that the severe erosion rates are located in steep-slope areas and on agricultural land intended for cereals.

Keywords: Erosion sensitivity, Universal soil loss equation, GIS tools.

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Incidence et impact des pathologies digitées sur la production laitière d’un élevage bovin laitier dans l’étage bioclimatique aride supérieur en Tunisie

R. BOURAOUI¹

W. MAAOUI¹

J. TOUMI²

G. BAKKARI ¹

¹ Ecole Supérieure d’Agriculture de Mateur, route de Tabarka 7030 Mateur, Tunisie

² Laboratoire Centrale des Analyses des Aliments pour Bétail

Abstract – This study was carried out to determinate the incidence of lameness on the performance of dairy cows. The experiment was conducted in El Hajeb farm in the region of Sfax with an upper arid bioclimatic stage. There were 623 lactations, 524 daily milk production performances, 415 fat contents and 487 protein contents. Records were collected between September 2005 and April 2008. 07% of dairy cows on this farm have problems with hooves, with higher rates in October and November, and the most frequent podal affections are located at the hind legs (79%). Lameness affected daily milk production (-4 Kg/cow/day) and reproduction. Milk quality (fat and protein contents) and somatic cells count are not affected by hooves pathologies.

Keywords: Cows, lameness, milk production, reproduction performances, Tunisia.

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