Hafiz Adéwalé Salami

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.

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.

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.

Striga hermonthica, causes up to 100% yield loss in maize production in sub-Saharan Africa. Developing Striga resistant maize cultivars could be a major component of integrated Striga management strategies. This study aims at assessing the agronomic performance of S1 breeding lines in improving maize for Striga resistance. Two hundred S1 lines have been evaluated under artificial infestation Striga and Striga-free conditions in Benin for two years during 2018 and 2019 growing seasons using alpha-lattice design (51 x 4) with two replicates. Twelve agro-morphological and Striga adaptive traits have been assessed. The tested lines have displayed high genetic variability for most agronomic and Striga adaptive traits. The S1 lines exhibited high grain yield than their parents with averages of 2,552.72±593 kg ha-1 and 2,965.67±635.86 kg ha-1 under Striga artificial infestation and Striga-free conditions, respectively. Grain yield has displayed high positive and significant genetic and phenotypic correlations with ears per plant and high negative correlations with days to 50% silking, ears aspect, and Striga damage rating at 8 and 10 weeks after planting (WAP). Useful traits like ears per plant, days to 50% silking, ears aspect, number of emerged Striga plants and Striga rating at 10 WAP could assist for indirect selection under Striga conditions. Based on the selection index, a total of 15 S1 lines have been identified as top ranking and can be used as sources of resistance or tolerance genes to Striga and further improvement in maize breeding in future.

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).

The objective of this screening is to identify genotypes with effective resistance genes against leaf blast. Two hundred rice accessions were collected in Benin's production areas and screened in upland ecology at Sowe (Glazoue, Benin). The experimental device used is an Alpha lattice 20 x 10 with 3 repetitions. The hierarchical ascending classification (HAC) allowed obtaining three large groups of accessions according to their behavior in relation to the populations of Magnaporthe oryzae present on the site: the C1 group composed of resistant genotypes (R), the group C2 composed of genotypes moderately sensitive (MS) and finally the group C3 that consists of sensitive genotypes (S). A highly significant difference was observed between genotypes based on recorded severity scores (five rating stages of disease and the AUDPC or Area Under the Disease Progress Curve). In general, the difference between the phenotypic variable (VP) and the genotypic variable (Vg) is relatively weak for all characters. All the traits studied had recorded high genotypic variation coefficients (GVC) and phenotypic variation coefficients (PVC) (> 20), with the exception of the first level of disease severity (Pyri1), thus justifying the high variability between genotypes with respect to resistance to disease. Heritability rate (H2%) coupled with high values of expected genetic gain compared to the mean (EGGM), indicated a low environmental influence in disease expression and a prevalence of the effect of additive genes in genetic determinism. The experiment has identified a pool of varieties with good behavior against blast disease that can be used as genetic control material in research and breeding programs in Benin.

A better approach to assess plant genetic diversity is the agro-morphological characterization. The main objective of this study was to investigate the morphological variability of 87 maize (Zea mays L.) accessions collected in different agro-ecological zones of southern Benin. Thus, 16 agro-morphological characters (seven quantitative and nine qualitative) were selected from the maize descriptors. The experimental design used is an incomplete randomized block with three replications. The mixed model analysis of two factors variance revealed a very highly significant difference for all accessions for each quantitative agro-morphological characteristic evaluated. The numerical classification of all corn accessions revealed five groups of accessions. The results of the stepwise discriminant analysis revealed five agro-morphological characteristics (germination days, female flowering, plant height, ear height and sensitivity to streak) most discriminating. The results of numerical classification supervised based on the most discriminating variables enable identification of the best accessions. Comparison of the two types of accessions (local and improved) revealed a significant difference among of them for agro-morphological characteristics with some exception. The groups obtained can constitute a database for breeders in a maize breeding program. Key words: Cultivars, biodiversity, selection, Zea mays L., Benin