Our study aims to characterize Plant Growth Promoting Rhizobacteria (PGPR) isolated from maize roots in five agroecological zones of central and northern Benin. Sixty samples were collected at the rate of four samples per village and three villages per agroecological zone. Rhizobacteria strains were isolated from these samples and biochemically characterized. These strains were analyzed for some of their PGPR traits like ammonia production and hydrogen cyanide following conventional methods. Microbiological investigation of these samples has shown that maize rhizospheres in central and northern Benin contain a high diversity of microorganisms. A total of nine species of maize Plant Growth Promoting Rhizobacteria were identified. Those PGPR include fiveBacillusspecies (B. polymyxa, B. pantothenticus, B. anthracis, B. thuringiensis, andB. circulans), threePseudomonasspecies (P. cichorii, P. putida, andP. syringae), andSerratia marcescens. The microbial diversity does not depend on the soil types. The microbial density, generally high, varies according to both soil types and agroecological zones. AllSerratiastrains (100%) have produced ammonia, whereas 80% ofBacillusand 77.77% ofPseudomonasproduced this metabolite. The hydrogen cyanide was produced by all isolates (100%) independent of their genus. These results suggest the possibility to use these rhizobacteria as biological fertilizers to increase maize production.

Plants constantly interact with a multitude of microorganisms that they select among other things through their roots. Some bacteria, known as plant growth promoting rhizobacteria (PGPR), are able to stimulate growth and control plant diseases, thanks to the expression of a wide range of beneficial properties to the plant. The aim of this work was to search for biofertilizing, plant-stimulating and biocontrol potentials in PGPR in central and northern Benin. To achieve this goal, the metabolic properties, especially phosphate solubilization, the production of indole acetic acid, hydrogen cyanide, ammonia, exopolysaccharides, certain enzymes and antifungal activity were investigated on nine rhizobacteria strains: Bacillus polymysa, Bacillus anthracis, Bacillus circulans, Bacillus thuringiensis, Bacillus panthothenicus, Pseudomonas cichorii, Pseudomonas putida, Pseudomonas syringae and Serratia marcescens. The results reveal that the three genera of rhizobacteria were producers of hydrogen cyanide, indole acetic acid, catalase and solubilized phosphate. All Pseudomonas and Serratia isolates were producers of exopolysaccharides, protease and lipase while 80% of Bacillus strains were lipase producers and 60% produced exopolysaccharides and protease. As regards the production of ammonia by rhizobacteria, 100% by S. marcescens, 78% of Pseudomonas strains and 80% of Bacillus strains produce them. These results show the possibility of using these rhizobacteria as biological fertilizers to stimulate growth, control fungal diseases and improve crop productivity in Benin. Key words: Rhizobacteria, Bacillus, Pseudomonas, Serratia, enzyme production, P-solubilizing bacteria, indole acetic acid (IAA).

Aims: Ageratum conyzoides L. is a small annual herbaceous highly odorous plant use in traditional medicine. The aim of this study is to evaluate in vitro antioxidant potential, toxicity and antimicrobial activity of aerial part extracts of A. conyzoides on strains potentially involved in vaginal infections. Methodology: An ethnobotanical survey has been carried out on A. conyzoides among ethnobotanists and traditional therapists in fifteen markets in the communes of Abomey- Calavi, Cotonou, Zogbodomey, Bohicon and Abomey in Southern Benin. The phytochemical screening was a qualitative analysis based on staining and precipitation reactions. Antimicrobial activity of A. conyzoides aqueous and ethanolic extracts was evaluated on reference and clinical strains of Staphylococcus aureus, Candida albicans and Escherichia coli using micro dilutions method in wells from. The toxicity of A. conyzoides extracts was determine using Artemia salina larvae, whereas the antiradical activity was evaluated using the Ferric Reducing Antioxidant Power (FRAP) method. Results: The survey showed that the population of Southern-Benin uses A. conyzoides according to different modes of preparation. Also, the administration in the treatment of a variety of pathologies affecting the female reproductive system. The phytochemical screening revealed the presence of flavonoids, tannins, anthocyanins, triterpenes and C- heterosides. The yield of 6.18% for the aqueous extract and 4.32% for the ethanolic extract as recorded. The highest inhibition diameter (24.05 ± 0.5 mm) was obtained using aqueous extract against the clinical S. aureus strain. In contrast, the lowest inhibition diameter (10±0 mm) was obtained against the S. aureus ATCC29213 with the same extract. The Minimum Inhibitory Concentration varied from 2.5 to 5 mg/ml. Both extracts show a bactericidal and fungicidal effect on the different strains studied but the sensitivity of the strains to the aqueous extract is better compared to the ethanolic extract. In addition, the aqueous extracts showed higher antioxidant power compared to the ethanolic extract. No toxicity is revealed for both extracts. Conclusion: The results obtained show that the aqueous and ethanolic extracts of the aerial part of A. conyzoides have antioxidant and antimicrobial properties on strains involved in vaginal infections and do not present a toxicity.

Maize plays an important role in agricultural production systems in all agro-ecological zones of Benin. Despite its importance, its production faces many constraints including soil fertility. One of the ecological technologies aimed at improving agricultural production is the use of soil microorganisms including arbuscular mycorrhizal fungi (AMF). This study aims to evaluate the effectiveness of Rhizophagus intraradices, an indigenous strain, on maize productivity in farmers' areas in the Research and Development (RD) sites of the North (Ouénou), Center (Miniffi), and South (Zouzouvou). Three maize producers were selected at each RD site, for nine maize producers. The experimental design was a randomized complete block of three treatments with three replications. The different treatments were (i) Control–farmer's practice, (ii) R. intraradices + 50% of the recommended dose of NPK and urea, and (iii) 100% of the recommended dose of NPK and urea. Soil samples from the different RD sites were taken at a depth of 0–20 cm before sowing for chemical analysis. The different growth parameters (height, crown diameter, and leaf area), grain yield, and endomycorrhizal infection of maize plants were evaluated. The results showed that the soils were moderately acidic (5.5 ≤ pH waters ≤ 6.8) and low in organic matter (0.95 ≤ 33 OM ≤ 1.17) regardless of the study area. The greater maize grain yield was recorded with application of 100% of the recommended dose of NPK and urea, and R. intraradices + 50% of the recommended dose of NPK and urea. In the RD sites at the South, Center, and North recorded with R. intraradices + 50% of recommended dose of NPK and urea, the grain yields of 1.9, 3.4, and 1.74 t/ha with an increase of 28, 38.21, and 13.21%, respectively, compared with farmer's practice. Mycorrhization frequencies in plants treated with Ri¹ N₁₅P₁₅K₁₅ vary between 37.44 and 51.67% in the three zones. The results of the current study have proven the potential use of R. intraradices in sustainable intensification of maize production in Benin.

Biotechnology proposes various ecological approaches to control climatic constraints, soil fertility and plant nutrition using biological products, such as biostimulants to achieve a healthy and environment-friendly agriculture. The aim of this study was to compare the effect of biostimulant-coated maize seed and biostimulant application on the growth, yield and nutritional status of maize in Benin. The trials were set up with 100 producers spread over the whole of Benin. The experimental design was a block of three treatments with 11 replicates per Research-Development (R-D) sites. The maize varieties 2000 SYNEE-W BENIN and TZL COMP 4-W BENIN were used. The best growth (height, stem diameter and leaf area) and yield performances (thousand grains weight and grains yield) were obtained by treatments T₂(Application of biostimulant + ½ NPK-Urea) and T₃(Seed coating with biostimulant + ½ NPK-Urea) compared to the farmers’ practice (T₁). A significant difference was observed between the different treatments for height, leaf area, 1000 grains weight and maize-grain yield. From one Research-Development site to another, a significant difference was also observed for all parameters. The treatment- Research-Development site interaction was also significant in most areas. The applied or coated biostimulant improved the uptake of nitrogen, phosphorus and especially potassium with higher significant difference compared to the recommended dose of mineral fertilizer. The two techniques of using the biostimulant combined with the half-dose of mineral fertilizer gave the better growth, yield and nutritional status compared to the farmers’ practice in all areas study. This biostimulant can be used to ensure food security and sustainable agriculture in Benin.