T. Stambouli ^1*

R. Hammami ²

A. Souissi ¹

A. Benalaya ¹

L. Laajili-Ghezal ¹

¹ Ecole Supérieure d’Agriculture de Mograne

² Institut National de la Recherche Agronomique de Tunisie

Abstract - The Virtual Water (VW) concept, defined by Allan (1997), as the amount of water needed to generate a product of both natural and artificial origin, this concept establish a similarity between product marketing and water trade. Given the influence of water in food production, virtual water studies focus generally on food products. At a global scale, the influence of these product’s markets with water management was not seen. Influence has appreciated only by analyzing water-scarce countries, but at the detail level, should be increased, as most studies consider a country as a single geographical point, leading to considerable inaccuracies. The main objective is the virtual water balance estimation of strategic crops in Tunisia (both irrigated and rainfed crops) to determine their influence on water resources management and to establish patterns for improving it. The virtual water balance was performed basing on farmer’s surveys and monitoring, crop and meteorological data, irrigation management and regional statistics. Results show that the majority of farmers realize a waste of the irrigation water especially for the vegetable crops and fruit trees. Thus, a good control of the cultural package may result in lower quantities of water used by crops while ensuring good production with a suitable economic profitability. Then, the virtual water concept integration in the production systems choice and policies affecting the use of water is very useful to save over this scarce resource and to support farmers in their production activities and maintaining the sustainability of farms.

Keywords: Virtual water, water balance, irrigation, Tunisia

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M. A. BARGOUGUI

School of Higher Education in Agriculture of Mateur

Abstract - The purpose of this study is to develop a selection approach to improve barley (Hordeum vulgare L.) grain yield, based on the various yield components, respectively, the spike-number per plant, grain-number per spike and the thousand-kernel weight. A complete diallel cross, including five barley genotypes, was analyzed for estimating variance of genetic effects, combining ability and heritability. The result revealed a highly significant general combining ability of the spike-number, sustained by high narrow sense heritability equal to 0.49. We noted that the genotypes Manel and INAT102 have the best values of general combining ability, and their progeny presented the most important specific combination abilities. Thus, selection based on the spikes-number appears to be quite adequate. The pedigree method is recommended, in which the genotypes Manel and INAT102 make good head that can be crossed together or with other parents to create new interesting genetic combinations for grain yield in barley.

Keywords: Diallel cross, barley (Hordeum vulgare L) grain yield components, genetic effects, heritability, selection approach.

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T. Grati ^{1, 2*}

R. Hellali ¹

S. Rezgui ¹

M. Ben Mimoun ¹

¹ INAT: 43 Avenue Charles Nicole, City Mahrajene, 1082, Tunis

² ISEP-BG: 49 Avenue «13 Août » Choutrana II, 2036 Soukra. Tunisia.

Abstract - High density of planting can lead to a decrease of the sunlight inside the canopy resulting in a decline of productivity. Hedging could constitute a good solution to resolve this problem. This experiment, was conducted during three years to compare the effect of two types of pruning on “Washington Navel” Citrus trees, i.e., the hedging and traditional one (ball shape), with a density of planting of 952 plants/ha. Results indicated that hedging decreased the chlorophyll change content of non-bearing fruits shoots between both sides, i.e., the sunniest one (S/E) and the most shaded one (N/W) with 1.751 and 1.510 mg/g, respectively. Indeed, compared with classic pruning, the mean values registered were 1.208 (S/E) and 1.572 mg/g (N/W). The hedging didn't show significant difference between both sides as for the chlorophyll content of the bearing fruits shoots (S/E: 1.574 and N/W: 1.510 mg/g). However, an important difference was observed for the control trees (bearing fruits shoots) between both sides (S/E: 1.975 mg/g; N/W: 1.375 mg/g). Hedging led to an optimal mineral status and a C/N ratio of 4.37 at the end of the experiment, whereas that of the control was 7.

Keywords: Citrus Orchard; Hedgerow Orchard; Radiation; High Density Planting, Pruning, chlorophyll, Foliar analysis

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H. MAAZAOUI ^{1, 2,4*}

J.J. DREVON ³

B. SIFI ¹

¹ Agronomic techniques and sciences laboratory, INRAT, Hédi Karray Street, 2080 Ariana, Tunisia.

² Faculty of sciences of Bizerte

³ INRA, UMR Eco&Sols, 2 Place Pierre Viala, 34060 Montpellier, France

⁴ Carthage University

Abstract - The commercial cultivar Bachar of faba bean (Vicia faba L. var. minor) was inoculated with a local rhizobial strain, named Mat.11, in twelve farmer fields of Mateur agro-ecosystem in northern which is a new agriculture reproach in Tunisia.. Phosphorus uptake, nitrogen accumulation, field yield and the soil analysis were studied. The results indicate a large spatial variation of the efficiency of the symbiosis rhizobia. Significant differences at P < 0.01 were found among the treatments Thus, without inoculation treatment suggests the potential of valuable rhizobial strains in some soils in nodulation and plant growth.. Nevertheless, the inoculation with Mat.11 increased significantly not only the total plant phosphorus uptake (from 1.46 mg P pl^-1 to 4.11 mg P pl^-1) but also nitrogen fixation (0.6 mg N pl^-1 to 3.22% mg N pl^-1) comparing to without inoculation treatment in many sites. The inoculation has also increased the grain yield comparing to the control treatment. It is concluded that faba bean inoculation with Mat11 improve significantly nodulation and plant growth. Further investigations should address the variation SNF among local genotypes and the symbiosis mechanisms to stabilize the legume yield in soils with low fertilizer input.

Keywords: Faba bean, nitrogen, phosphorus, rhizobia, symbiosis.

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R.I. Zoghlami^1,2*

N. Ben Aissa²

H. Hamdi¹

S. Mokni-Tlili¹

M.N. Khélil³

N. Jedidi¹

¹ Centre de Recherche et des Technologies des Eaux, Université de Carthage, B.P 273, Soliman 8020, Tunisie

² Institut National Agronomique de Tunisie, 43, Av. Charles Nicolle 1082, Tunis, Tunisie

³ Institut National de Recherche en Génie Rural, Eaux et Forêts, B.P 10, Ariana 2080, Tunisie

Abstract - This study aimed to determine the effect of urban sewage sludge re-use on two light-textured soils differentiated by the rate and type of clay in the region of Oued Souhil, Nabeul. Experimental soil characterization showed that the first one has a sandy texture composed mainly of quartz and calcite with a clay content of 5%. The second soil is sandy loam with a higher clay content (12%) represented by illite and kaolinite. In addition, both soils were not saline and showed no heavy metal contamination for the two studied depths (0-20 cm and 20-40 cm). However, the C/N ratio was lower in the sandy soil, which was correlated with similarly low BC/BN ratio. These two soils were amended with increasing doses of urban sludge (40, 80 and 120 t ha-1) and incubated under controlled conditions for 38 days. During this period, we followed the mineralization of organic carbon and microbial biomass-C. This experiment permitted to determine the potential of carbon mineralization as well as the potential of biomass-C proliferation that increased with sludge dose. On the other hand, we observed a strong correlation between the mineralized carbon and microbial biomass carbon, which was around 87% and 95% for the sandy loam soil and the sandy soil, respectively.

Keywords: Microbial Biomass, Incubation, Soil texture, Sewage sludge

Résumé - Cette étude au laboratoire vise à analyser l’effet de l’amendement de boues résiduaires sur deux sols agricoles légers de la région d’Oued Souhil à Nabeul, différenciés par le taux et le type d’argile. En effet, la caractérisation initiale montre que l’un des deux sols est à texture purement sableuse constitué principalement de quartz et de calcite avec un taux d’argile de 5%. Le deuxième sol est sableux-limoneux avec un taux d’argile équivalent à 12% dont la fraction minéralogique est composée principalement d’illite et de kaolinite. Ces deux sols ne sont pas salins et sont peu contaminés par les métaux lourds pour les deux profondeurs étudiées (0-20 cm et 20-40 cm). Toutefois le rapport C/N est considéré comme faible pour le sol sableux et moyen pour le sol sableux limoneux ce qui est peut être expliqué par un rapport BC/BN plus faible pour le sol sableux de l’ordre de 18.5 contre 53 pour le sol sableux limoneux qui possède une flore microbienne plus importante. Suite à l’incubation in vitro de ces deux sols amendés avec des quantités de boues croissantes de 40, 80 et 120 t ha-1, nous avons suivi la minéralisation du carbone organique et le carbone de la biomasse microbienne durant 38 jours. Cette expérimentation nous a permis de déterminer le potentiel de minéralisation du carbone ainsi que le potentiel de prolifération de la biomasse-C qui augmentent en fonction de la dose de boues ajoutées. De plus, nous avons observé une forte corrélation entre le carbone minéralisé et le carbone de la biomasse microbienne qui est de l’ordre de 87% et 95% pour le sol sableux limoneux et le sol sableux respectivement.

Mots clés: Biomasse microbienne, Incubation, Texture de sol, Boue résiduaire

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B. Zougari-elwedi ^1*

W. Issami ²

A. Msetra ¹

M. Sanaa ³

D. Yolande ⁴

A. Lounes-Haj Sahraoui ⁵

¹ Regional Research Center on Oases Agriculture of Degache- Tozeur. Road of Tozeur Km 1, Degache 2260, Tunisia.

² Faculty of Mathematical, Physical and Natural Sciences. University of Tunisia El Manar, 2092. EL MANAR 2 Tunisia.

³ National Institute of Agronomy of Tunisia. Soil Sciences and Environment Laboratory, Tunis Mahrajene, Tunisia, 43, Av. Charles Nicole, 1082.

⁴ Eastern Cereal and Oilseed Research Center (ECORC) Ottawa. 960 Carling Avenue, ON K1A 0C6 Canada. 

⁵ Unité de Chimie Environnementale et Interaction sur le Vivant (UCEIV). Université du littoral Côte d’Opale (ULCO). 50 rue Ferdinand Buisson.62228 CALAIS cedex.

Abstract - In the Djerid palm groves, soils are often poor in mineral nutrients. Therefore, mycorrhizal symbiosis has a beneficial effect on date palm growth.But studies made on this symbiosis remains again very limited and even absent in Tunisia. In fact, 27date palms divided in to nine palm groves, have been studied for their rhizospheres and we can notice the presence in the roots of different date palm cultivars, four genera mycorrhizal fungi (Glomus, Acaulospora, Sclerocystis and Scutellospora). The predominant genus identified was Glomus.Eight species ofarbuscular mycorrhizal fungihave been recorded in all study sites: Glomus mosseae, Glomus constrictum, Glomu stortuosum, Glomus irregulare, Glomus sp., Acaulospora cavernata, Scutellospora calospora and Sclerocysti srubiformis. Their frequency and their rates vary depending on the sporulation sites and seasons. Seasonal variation of colonization by arbuscular mycorrhizal fungal (AMF) hyphae in all 8species has been characterized in vertical profiles and at different lateral distances from the date palm trunk. We can notice also that, the AMF colonization levels of field date palm roots were found to be according to the seasons. The peaks of colonization observed during autumn could be due to the sporadic rains that can activate fungus colonization and the tendency to associate depression with winter. The most important populations reached their maximum at the aplomb of the date palm crown and mainly 50 cm from the date palm trunk.The different AMF distributions were recorded at 20–40 cm soil depth; they refer to the most common roots of date palm.

Keywords: Mycorrhiza, colonization, symbiosis, season, date palm.

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