Pigeon pea (Cajanus cajan L.) is a legume with an important source of proteins, grown in several tropical and subtropical regions. However, despite its great importance, especially in tropical regions facing food and nutritional insecurity, pigeon pea remains one of the oldest and least valued food crops in West Africa, particularly in Senegal. The aim of this study was to contribute to a better understanding of the diversity of rhizobia associated with three pigeon pea provenances in three regions of Senegal (Fatick, Nioro and Kaffrine), with a view to their exploitation as microbial biofertilizers. Soil samples were collected from rhizosphere of pigeon pea plants in the three regions. Shadehouse trials were carried out to determine the most probable number of bacteria (MPN), as well as the phenotypic and genetic diversity of rhizobia by trapping with pigeon pea seeds from the three provenances. The results revealed a variability in MPN between the three study sites. Bacterial isolation from root nodules determined that pigeon pea associates more with fast-growing bacteria. A collection of 87 isolates was obtained from the plant nodules cultivated in the three sites. Amplification of the rDNA ITS region, followed by enzymatic digestion, disclosed 35 genetic profiles, including 4 common to Fatick and Kaffrine, 2 to Fatick and Kaffrine, 1 to Nioro and Kaffrine, 8 specific to Fatick, 8 to Kaffrine and 5 to Nioro. At the end of the infectivity test with 56 bacterial isolates, considered under controlled conditions, only 29 re-infected the host-plant. A positive effect of inoculation with some bacterial isolates (F12p, N23, N22, N5, K3 and K16p) was noted for chlorophyll content and certain plant growth parameters (nodule number and weight, shoot and root dry weight). This study underlined that some of the bacterial strains may be potential candidates for improving growth and productivity of pigeon pea in Senegal.

Pigeon pea (Cajanus cajan L.)Millsp., often referred to as the meat of poor people, is a valuable underutilized agricultural resource in Africa, particularly in Senegal. This legume offers a diverse range of food and environmental benefits, making it a key element for food security and sustainability of agricultural systems, especially in tropical and subtropical regions.The aim of this study was to evaluate the density and diversity of arbuscular mycorrhizal fungi (AMF) associated to three provenances of pigeon pea cultivated in three soils from two regions in Senegal.My corrhizal parameters were determined in the three soil origins; and added to growth parameters after trapping culture with three pigeon pea provenances in these soils for 4 months. The results revealed significant differences among the soil origins and the presence or absence of theplant for AMF density and diversity, and mycorrhizal potential. Seven morphotypes of AMF belonging to five genera (Racocetra, Scutellospora, Dendiscutata, Gigaspora and Glomus) were identified. Spore density was higher in Kaolack and lower in Kaffrine.

Microbial bioinoculation in plants is considered essential, as it helps reduce pollution levels and enhances crop productivity. The aim of this study is to evaluate the effect of microbial inoculation with selected rhizobia on the agronomic parameters of peanut plants. Peanut (Arachis hypogaea) root nodules, harvested in situ, were surface disinfected and crushed in petri dishes. Isolations were carried out from nodular crushed and the characteristic rhizobia colonies were purified. After a nodulation test of the purified isolates, the nodulating strains were subjected to an efficiency test. The first five strains showing the most satisfactory results on growth parameters were selected for the actual inoculation test. The growth, nodulation and mycorrhization parameters, as well as the number and weight of plant pods, were determined, after 3 months of crop. Results show a significant improvement in most of the parameters studied. Indeed, plant height was significantly improved from 38.33±2.86 (control) to 49.73±10.90 cm by inoculum R1 and from 38.33±2.86 to 59.22±9.87 cm by inoculum R2 (p = 0.05). These same inocula also significantly improved shoot dry weight with values ​​ranging respectively from 4.43±0.86 (control) to 5.41±0.87 g (R1) and from 4.43±0.86 to 6.07±1.38 g (R2). Except for the mixed inoculum, all treatments applied significantly improved the nodules number. The values ​​varied from 72.33±7.47 to 109.89±15.86 ; 109.33±21.18 ; 110.00±18.49 ; 105.67±16.9 and 113.11±20.63 nodules respectively for inocula R1, R2, R3, R4 and R5 (p = 0.05). Pods weight was significantly improved from 2.15±0.73 to 4.00±1.01 ; 4.02±0.97 and 3.80±0.96 g respectively by the inocula R3, R1, R2 (p = 0.05). The best results were obtained with inocula R1 and R2. These results confirm once again the stimulatory effect of rhizobia on the agronomic parameters of peanut. These inocula can be used as a biofertilizer to improve peanut crop yield.

In Senegal, rising temperatures are projected to reduce maize yields due to a shortened growth duration, while elevated CO 2 fertilization may increase peanut yields under climate change. However, there is limited evidence on climate change impacts if crop cultivars change and systems intensify, which is expected to occur in parallel with climate change. For climate-adapted agriculture, the performance of improved agronomy and varieties should be evaluated under current and future climate scenarios. This study assesses the impact of climate change on crop yields of two varieties of peanut and maize at each under current and intensified fertilization. Simulations were performed for mid-century (2045–2074) and end-century (2070–2099) relative to a baseline (1981–2010) using the SIMPLACE modeling framework at 0.5° resolution. Climate projections from nine global climate models (GCMs) were used under SSP2-4.5 and SSP5-8.5 scenarios. Soil data was derived from the Harmonized World Soil Database. The results indicate that the impacts of climate change on crop yields differed by crop. Peanut showed an increase in yield of up to 45% and a decrease for maize of up to 25% by the end of the century. Peanut yield gains were higher under the intensification fertilization case compared to the current fertilization case, whereas for maize, losses were high in the intensification case. Furthermore, yield losses are more substantial in the southern and western parts of the country for both crops. Additionally, for maize, yield losses were higher for the short cycle variety than the long cycle variety; there was little difference between varieties for peanut.

Endophytic bacteria are microorganisms that play critical roles in plant physiology and ecosystem function. Among them, plant growth-promoting rhizobacteria (PGPR) significantly promote plant growth, enhance stress resistance, and increase crop yields. However, limited information is available on the endophytic bacteria associated with cotton roots (Gossypium hirsutum L.). This study aimed to determine the diversity of plant growth-promoting (PGP) functions of cotton root endophytic bacteria cultivated in soils from two geographical regions in Senegal: Koussanar and Syllacounda. A cotton trapping culture was conducted using soil samples collected from these two regions to isolate and characterize root endophytic bacteria. Various traits, including morphological characteristics (size and color), physiological traits (Gram and catalase tests), and biochemical traits (phosphate solubilization, siderophore production, and auxin production), were measured in this study. The results revealed significant differences in soil properties and environmental conditions between the two regions. A total of 96 endophytic bacteria with distinct PGP traits were isolated from cotton roots in Koussanar, while 79 were isolated from the Syllacounda region. Among the 175 isolates, 82 were identified as Gram-negative, 35 exhibited catalase activity, and 48 emitted green fluorescence. All isolates tested positive for indole-3-acetic acid (IAA) production, while 124 produced siderophores, and only 68 were capable of solubilizing phosphorus. When comparing the two sites, Koussanar had a higher number of Gram-negative isolates that were catalase-positive and produced siderophores. In contrast, Syllacounda had a greater number of isolates with fluorescence activity and phosphorus solubilization abilities. Some endophytic bacterial isolates, such as K2, K13, K20, K35, K49, K53, K54, and K60 from Koussanar, as well as S5, S6, S11, S15, S20, S21, S38, S40, S47, S51, S64, S72, and S79 from Syllacounda, demonstrated the best PGP performances. The findings of this study suggest that these endophytic bacteria are promising candidates as bioinoculants for promoting cotton plant growth and protection.

Plant inoculation with selected microorganisms remains a good alternative environment friendly. It minimizes the excessive use of chemicals fertilizers and increases the yield. The aim of the present study is to evaluate the effect of dual inoculation with arbuscular mycorrhizal fungi (AMF) and rhizobia selected on growth parameters of peanut seedlings, in greenhouse conditions. The experiment was conducted in a greenhouse (5°23 N to 4°0 W) located at the University Nangui Abrogoua (UNA) in Abidjan, Côte d’Ivoire during three months. Peanut seeds were sown into plastic bags containing 1 kg of non-sterile substrate. The fungal inoculum was added at sowing and after 5 days of crop, 5 mL of bacterial suspension was added around the rootlet. Plants were watered regularly and their height was measured every two weeks. After three months of crop, plants were harvested ; plant growth, mycorrhizal and nodulation parameters were measured. Nodules were detached, counted, and weighted per plant. The aerial and root weights were determined after drying each compartment. Then, the mycorrhization parameters were determined after staining the roots. Results show better growth of inoculated plants compared to non-inoculated plants. Indeed, dual inoculation with both AMF and rhizobia has significantly improved yield paramaters such as the number and weight of pods and nodules number. Significant increase in pods number from 1,44±0,53 to 2,33±0,87 (α = 0.05) was observed. Pods weight was significantly increased from 2,15 ±0,73 to 4,09±0,76 g by dual inoculation. As for nodules number, a significant increase from 72,33±7,47 to 87,20±9,78 (α = 0.05) was also observed. These results confirm once again stimulatory effects of these symbionts, described by several authors. Indeed, positive effects of single inoculation with rhizobia or AMF and dual inoculation with both have been widely demonstrated on many plant species.

The benefits of arbuscular mycorrhizal fungi (AMF) for the nutritional quality, yield and nutrient uptake by plant have been investigated in maize. However, the variability in mycorrhizal dependency (MD) and root colonization by AMF among maize variety groups is still poorly documented in the Kivu region. This study aimed to investigate the variation in mycorrhizal dependency to Rhizophagus irregularis among five maize varieties from South-Kivu and one from Senegal using a greenhouse experiment. AMF inoculation significantly influenced the intensity of root colonization, growth and physiology of maize varieties, while no change in root colonization frequency was observed. Three of six varieties used responded positively to AMF inoculation. For these varieties, inoculation with R. irregularis significantly improved plant height, stem diameter and SPAD values. The same significant positive trend was observed for maize total shoot and root biomasses (p < 0.05). Significant variation in MD was observed among maize varieties (p = 0.00012) and could be attributed in part to genetic and physiological factors controlling host/fungus compatibility. The non-metric multidimensional scaling (NMDS) analysis discriminated varieties into two main groups, including those with high MD (MD˃5

Communities of soil nematodes are an essential component of soils’ functioning. Although some nematodes can damage crops seriously, free-living soil nematodes appear to be beneficial to the soil. Chemical treatments do not discriminate between the two types. Thus, using amendments from native shrubs residues could be an alternative solution by influencing the different trophic communities of nematodes and the microbial activity of soil. The objective of the present study was to determine the best amendments for benefiting the free-living nematodes and their relationship with enzymatic activities in the soil. The experiments used a six-treatment random-block design, and were performed in a shade house on the farm of the University of Gaston Berger (UGB). The treatments consisted of residues from Piliostigma reticulatum , Boscia senegalensis , and Crotalaria juncea ; a standard compost applied at 10 t/ha; a farmer practice of applying NPK fertilizer at 200 kg/ha; and a control (no amendments). Total abundances of nematodes, the abundance of each group, and the nematodes’ ecological indices were determined. In addition, the enzymatic activities (fluorescein di-acetate, ß-glucosidase, and phosphatase acid) were determined in samples of rhizospheric soil. The increase in total abundance of nematodes was significantly greater in soil amended with residues of B. senegalensis and C. juncea than in soil that was either not amended, or amended with NPK fertilizer. Indices of taxonomic diversity did not differ significantly between the treatments. However, soils amended with B. senegalensis and C. juncea had the highest enrichment index (EI), and the lowest Nematode Channel Ratio (NCR). Compared to other treatments, B. senegalensis residues favour omnivores and increase enzymatic activities. Thus, these residues—which induce ‘bottom-up’ and ‘top-down’ controls on nematode populations—are the best amendment for benefiting nematode communities by developing free-nematode communities and stimulating microbial activity.

In plant roots, arbuscular mycorrhizal fungi (AMF) are the most prevalent microsymbionts, and thereby provide many key ecosystem services to natural and agricultural ecosystems. Despite AMF's significance for the environment and the economy, little is known about the mycorrhizal inoculum potential and diversity of AMF associated with orphan African cereal crops, specially fonio millet (Digitaria exilis stapf.) under field conditions. We hypothesized that the type of fonio millet agroecosystem influences the AMF density and distribution in soils. We therefore, assessed the inoculum potential, density and diversity of AMF spores and soil enzyme activities in five fonio millet agroecosystems belonging to three climatic zones (Sudanian, Sudano-Sahelian and Sudano-Guinean). By combining AMF spore identification from field-collected soils and trap culture, 20 species belonging to 8 genera (Acaulospora, Ambispora, Dendiscutata, Gigaspora, Glomus, Racocetra, Sclerocystis and Scutellospora) were identified. Glomus was the most represented genus with 8 species, followed by Gigaspora (5 species) and Acaulospora (2 species); the remaining genera were each represented by one species. Except for Ambispora which was not found in the Sudanian area, all genera occurred in the three climatic zones. The abundance and diversity of AMF species and FDA-hydrolytic and phosphatase activities varied between fonio millet agroecosystems as well as between climatic zones. Soil pH and soil texture were the variables that best explained the density and distribution of AMF spores. Our results contribute to paving the way towards the development of microbial engineering approaches for agronomic improvement of fonio millet.

Rhizosphere microorganisms, particularly arbuscular mycorrhizal fungi (AMF), play a vital role in enhancing sustainable maize production. However, uncertainty persist regarding the influence of climate variables and soil properties on mycorrhizal colonization (MC) of maize and the abundance of AM fungal spores in the field. This study aimed to explore the environmental factors such as site climate variables, soil physicochemical properties and topography and vegetation variable, affecting the natural MC of maize and the density of AMF spores. The study hypothesizes that natural maize mycorrhizal colonization and AMF spore density vary significantly across different sites and agroecological zones. It further posits that climatic and edaphic variables predominantly explain the observed variation in mycorrhizal parameters. To assess the impact of these factors, a field study was conducted in 32 sites across three territories in the province of South Kivu, namely Kabare, Walungu, and Uvira. Rhizospheric soil and maize roots were collected from different sites. Maize MC varied significantly among sites, with Kabare and Walungu showing high colonization rates (52.1% and 44.7%, respectively) compared to Uvira (26.40%). Meanwhile, spore density was significantly higher in Uvira (1331.7 spores g-1 soil) than in Kabare (518.9 spores g-1 soil) and Walungu (468.58 spores g-1 soil). Correlation analysis indicated that maize MC was influenced by site climate and soil properties. The PLS-SEM model demonstrated that 76.5% (R2) of the total variance in maize root MC was explained by climatic variables and soil chemical properties. Compared to soil chemical properties, climate characteristics had a more pronounced impact on maize MC. Maize MC was inversely correlated with temperature, C and available P content, while being directly and positively correlated with altitude, rainfall, and base saturation rate. Furthermore, 68.5% (R2) of the spore density variability of AMF was explained by climatic variables and soil physical properties. Spore density was inversely correlated with sand and clay content, field capacity, rainfall, and altitude, while being positively correlated with temperature. The results of this study indicate that climatic conditions exert a more pronounced influence on the mycorrhizal colonization of maize and the density of AMF spores than soil characteristics.

A new Bradyrhizobium vignae strain called ISRA400 was isolated from groundnut (Arachis hypogaea L.) root nodules obtained by trapping the bacteria from soil samples collected in the Senegalese groundnut basin. In this study, we present the draft genome sequence of this strain ISRA400, which spans approximatively 7.9 Mbp and exhibits a G+C content of 63.4%. The genome analysis revealed the presence of 48 tRNA genes and one rRNA operon (16S, 23S, and 5S). The nodulation test revealed that this strain ISRA400 significantly improves the nodulation parameters and chlorophyll content of the Arachis hypogaea variety Fleur11. These findings suggest the potential of Bradyrhizobium vignae strain ISRA400 as an effective symbiotic partner for improving the growth and productivity of groundnut crop.

The impact of earthworms and plant growth-promoting rhizobacteria (PGPR) on the remediation in polluted dumpsite soil was performed in a greenhouse pot culture with Acacia mangium inoculated or not (control: T0) with Pontoscolex corethrurus (T1) and with Bradyrhizobium (T2); and inoculated with Pontoscolex corethrurus and Bradyrhizobium (T3). Our results showed the presence of Bradyrhizobium and/or earthworms significantly increase (P < 0.05) in the height (2-fold), total dry biomass weight (7- to 15-fold) and metal uptake of the plant (2 to 10-fold), as compared with the non-inoculated plant. The presence of both inoculants (Bradyrhizobium and earthworm) enhanced soil Pb/Ni/Cr mobility and bioavailability in metal-contaminated soil, and increased 15-fold the total plant biomass and 10-fold metal accumulation in plant biomass, as compared with plant inoculated with earthworms or Bradyrhizobium. In addition, the presence of earthworms and/or Bradyrhizobium promoted the phytoimmobilization process of Ni, Cr and Pb preferentially in Acacia mangium roots than in shoot tissue. Our experiments highlight the importance of soil organisms on the phytoremediation efficiency. It appears that earthworms and/or Bradyrhizobium have the potential to enhance the phytoextraction efficiency of plants in metal-contaminated soil.

L’accumulation de substances toxiques telles que des éléments traces métalliques (ETM) dans les sols du site de la décharge de M’Ploussoue de Bonoua pourrait affecter la prolifération des microorganismes plus spécifiquement la sporulation et la germination des spores des Champignons Mycorhiziens à Arbuscules (CMA).C’est pour répondre à cette préoccupation que la présente étude s’est fixée pour but d’évaluer le potentiel mycorhizien des champignons indigènes des sols pollués de la décharge du Parc M’Ploussoué de Bonoua grâce à un test biologique avec Zea mays L. et Acacia mangium, comme des plantes pièges des microorganismes indigènes. Ainsi, après 45 jours de culture, le potentiel mycorhizien a été déterminé à partir de l’extraction desspores par tamisage humide, de la coloration des racines au bleu de trypan et du dénombrement des souches fongiques. L’analyse macroscopique des spores et des souches fongiques a révélé la présence du genre Glomus sp. (90%) appartenant à l’ordre des Glomales et également d’espèces peu spécifiques à acacia comme Aspergillus sp., Fusarium sp., Trichoderma sp. et Penicillium sp. L’examen microscopique des racines de Zea mays et de Acacia mangium a indiqué une fréquence (80 to 90%), une intensité (15 to 40%) de mycorrhization et un nombre d’arbuscules (87,5%) et de vésicules (12 to 100%) très importants sur le sol pollué. La formation des types de structures endomycorhiziens (vésicules et arbuscules) suggère la présence de champignons endomycorhiziens vesiculo-arbusculaires (CMVA) symbiotiques capables d’initier une symbiose et de favoriser un meilleur développement Acacia mangium malgré la pollution. Au su de ces résultats, les spores des CMVA de ce site pourraient être utilisées dans la remédiation du site. English title: Assessment of the Mycorrhizal Potential of Polluted Soils of M’Ploussoue Landfill in Bonoua, Côte D’Ivoire The accumulation of toxic substances such as metallic trace elements (TME) in landfill soils of the M'Ploussoue site in Bonoua could affect microorganisms proliferation specifically the sporulation and germination of spores of Arbuscular Mycorrhizal Fungi (AMF). To address this concern, this study was to assess the mycorrhizal fungi indigenous potential of polluted soils of M’Ploussoue landfill in Bonoua by a biological test with Zea mays L. and Acacia mangium Wild, as an host plants in trap culture of indigenous mycorrhizal fungi. After 45 days of culture, the mycorrhizal potential was determined through the extraction of the spores by soil wet sieving, the roots clearing with trypan blue and the count of fungal strains. The macroscopic analyzis of the spore and fungi strains revealed the majoritory presence of Glomus spp. (90%) belonging to the Glomal orderand also the presence of nonspecific fungi especies to acacia as Aspergillus spp., Fusarium spp., Trichoderma spp. and Penicillium spp. The microscopic examination of Zea mays and Acacia mangium roots indicated frequency (80 to 90%), intensity (15 to 40%) and arbuscule contents (87.5%) and vesicles (12 to 100%) are very important in polluted soil. The formation of typical endomycorrhizal structures (vesicles and arbuscules) suggests the presence of symbiotic vesiculo-arbuscular endomycorrhizal fungi (VAMF) able to promote better Acacia mangium development despite soil pollution. Based on these results, the spores of VAFM fungi from this site could be used in the remediation of the site.

The papaya tree is not very exploitable on the international market because of the post-harvest decline of the fruits. In this study, we identified arbuscular mycorrhizal fungi (AMF) from the rhizosphere of papaya in two agroecological zones of Cameroon (Njombe-Pendja: NP and Yaounde: Y). Morphological studies on the density, the rate of root colonization, the diversity of AMF species were evaluated. Molecular identification of AMF was performed by sequencing the small subunit (SSU) 18S rDNA gene region from soil samples. These genes were amplified from the AML and NS2 primers. The total number of spores per 100 g of dry soil was significantly different (P<0.05) depending on the sites, ranging from 391 in NP to 790 in Y sites. The frequency and intensity of root colonization was not significantly different in the two sites. Eleven (11) AMF belonging to seven (7) genera (Scutellospora, Gigaspora, Acaulospora, Entrophospora, Funneliformis, Glomus and Racocetra) were recorded. Two AMF species (T1: Scutellospora rosa and T6: Racocetra gregaria) were recorded at NP and absent at Y. The Shannon-Wiener index revealed a low diversity of AMF species. Homogeneity of species was recorded. Molecular analysis reveals that the AMF species obtained have sizes of 250 bp. Key words: Arbuscular mycorrhizal fungi, Carica papaya L., fungal, molecular and morphological identification, rhizosphere.

This study aimed to investigate the role of arbuscular mycorrhizal (AM) fungi on biological N fixation in Vachellia seyal and transfer of fixed N2 from V. seyal to intercropped Sporobolus robustus under greenhouse conditions. Both plants were grown individually in pots to prevent root contact (“Solid barrier” treatment) or together in two-compartment containers delimited by a plexiglass plate with holes either covered with a 30 μm nylon mesh allowing only hyphal connections between plant roots (“Mesh barrier” treatment), or without nylon mesh allowing hyphae and roots to intermingle (“No barrier” treatment) in a low-nutrient soil. Both plant species were inoculated with the AM fungal Rhizophagus irregularis IR27 strain (“Myc+” treatment) or not inoculated (“Myc-” treatment), whereas all V. seyal seedlings were inoculated with a rhizobial strain Ensifer sp. LCM 4579 (“Nod+” treatment). The 15 N isotope dilution method was used to determine the amount and proportion of atmospheric N fixed by V. seyal (%Ndfa) and the total fixed N that was transferred to intercropped S. robustus. Mycorrhizal inoculation factor had a significantly effect on plant growth parameters and shoot N concentration in V. seyal, but not in S. robustus. The estimated proportions of N fixed by V. seyal was higher in Myc + treatment (65%) than in Myc- treatment (42%) as well as for the amount of fixed N. About 14% of fixed N were transferred to S. robustus from AM fungal links, whereas N transfer via exudation plus transfer through mycorrhizal network reached 19.5%. The implications of these results are discussed.

Our planet is marked by significant climatic variations, particularly with the warming of temperatures and the variation in rainfall. In sub-Saharan Africa, the impacts of climate change are more pronounced because agriculture is highly dependent on climate, hence its vulnerability to climate variability (Vanluwe et al., 2011). In the context of changing environmental conditions, the use of innovative agricultural practices to contribute to plant adaptation is necessary to support food security challenges. Agroecological practices to improve crop yields and sustainable soil fertility management. Soil is the main reservoir of biodiversity as it hosts a very high diversity of interacting living species, which can be distinguished according to their size, macrofauna, mesofauna and microorganisms that constitute a particularly important component of soil (Brady and Weil, 2002), particularly for the provision of ecosystem services to humans. This work is therefore interested in studying the contribution of arbuscular mycorrhizal fungi (AMF) to the growth of millet (Pennisetum glaucum) under warmer temperature conditions and the behaviour of microbial community in soil of millet growing. Millet is grown in a plant climate chamber and inoculated with a selected mycorrhizal strain. These millet growing conditions were carried out in two different temperatures: 32°C (normal temperature) and 37°C (warmer temperature). The results showed that in conditions of warmer temperature the inoculation induced a significant vegetative growth of millet even with a low intensity of mycorrhization and so it improves microbial nutrient mineralization mediate vegetation growth. In soil of millet growing, a significant increase in microbial biomass with 42.7 in warmer temperature condition compared to control temperature 16.7. Results of DGGE shows also a soil abundance and SMB diversity of the total fungal community was noted under warmer temperature condition. This study showed that climate variation may affect soil symbiosis but not the potential for promoting plant growth of fungi. The use of arbuscular mycorrhizal fungi on the one hand as a biofertilizer can be an alternative in the context of reducing chemical inputs in agriculture and developing ecologically intensive agriculture (EIA) and on the other hand an adaptive practice to apprehend the predicted climate changes.

The intensification of biological processes coping with salt stress became a major issue to mitigate land degradation. The Sine-Saloum Delta in Senegal is characterized by salt-affected soils with vegetation dominated by salt-tolerant grass Sporobolus robustus and shrubs like Prosopis juliflora. Plant experiments in controlled conditions suggested that arbuscular mycorrhizal (AM) fungi might be the key actors of facilitation process observed between S. robustus and P. juliflora, but the AM fungal community determinants are largely unknown. The current field-based study aimed at (1) characterizing the environmental drivers (rhizosphere physico-chemical properties, plant type and season) of the AM fungal community along an environmental gradient and (2) identifying the AM fungal taxa that might explain the S. robustus–mediated benefits to P. juliflora. Glomeraceae predominated in the two plants, but a higher richness was observed for S. robustus. The pH and salinity were the main drivers of AM fungal community associated with the two plants, negatively impacting richness and diversity. However, while a negative impact was also observed on mycorrhizal colonization for S. robustus, P. juliflora showed opposite colonization patterns. Furthermore, no change was observed in terms of AM fungal community dissimilarity between the two plants along the environmental gradient as would be expected according to the stress-gradient and complementary hypotheses when a facilitation process occurs. However, changes in intraspecific diversity of shared AM fungal community between the two plants were observed, highlighting 23 AM fungal OTUs associated with both plants and the highest salinity levels. Consequently, the increase of their abundance and frequency along the environmental gradient might suggest their potential role in the facilitation process that can take place between the two plants. Their use in ecological engineering could also represent promising avenues for improving vegetation restoration in saline Senegalese’s lands.

Land salinization is a major constraint for the practice of agriculture in the world. Considering the extent of this phenomenon, the rehabilitation of ecosystems degraded by salinization has become a priority to guarantee food security in semi-arid environments. The mechanical and chemical approaches for rehabilitating salt-affected soils being expensive, an alternative approach is to develop and utilize biological systems utilizing salt-tolerant plant species. Casuarina species are naturally halotolerant, but this tolerance has been shown to be improved when they are inoculated with arbuscular mycorrhizal fungi (AMF) and/or nitrogen-fixing bacteria (Frankia). Furthermore, Casuarina plantations have been proposed to promote the development of plant diversity. Thus, the aim of the current study was to evaluate the impact of a plantation comprising the species Casuarina inoculated with AMF and Frankia on the diversity of the sub-canopy and adjacent vegetation. Work was conducted on a plantation comprising Casurina equisetifolia and C. glauca variously inoculated with Frankia and Rhizophagus fasciculatus prior to field planting. The experimental area of 2500 m2 was divided into randomized blocks and vegetation sampling was conducted below and outside of the Casuarina canopy in 32 m2 plots. A total of 48 samples were taken annually over 3 years, with 24 taken from below the Casuarina canopy and 24 from outside the canopy. The results obtained show that co-inoculation with Frankia and Rhizophagus fasciculatus improves the height and survival rate of both species. After 4–5 years, there was greater species diversity and plant biomass in the sub-canopy environment compared with that of the adjacent environments. Our results suggest that inoculation of beneficial microbes can improve growth of Casuarina species and that planting of such species can improve the diversity of herbaceous vegetation in saline environments.