This study aimed to assess the effects of three plant growth promoting rhizobacteria (PGPR) and chitosan either singly or in combination on maize seeds germination and growth and nutrient uptake. Maize seeds were treated with chitosan and bacterial solution. The germination and growth tests were carried out in square Petri dishes and plastic pots. The combination chitosan-A. lipoferum-P. fluorescens has increased the seeds vigor index up to 36.44% compared to the control. In comparison to the control, P. putida has significantly improved root weight (44.84%) and germinated seed weight (31.39%) whereas chitosan-P. putida has increased the shoot weight (65.67%). For the growth test, the maximal heights (17.66%) were obtained by plants treated with the combination A. lipoferum-P. fluorescens-P. putida. Chitosan-P. fluorescens induced the highest increases of leaves per plant (50.09%), aerial (84.66%), and underground biomass (108.77%) production. The plants inoculated with A. lipoferum had the large leaf areas with an increase of 54.08%, while combinations P. fluorescens-P. putida and chitosan-A. lipoferum improved the aerial and underground dry matter of plants to 26.35% and 18.18%. The nitrogen content of the plants was increased by chitosan-A. lipoferum-P. fluorescens-P. putida with an increasing of 41.61%. The combination of chitosan and PGPR can be used as biological fertilizers to increase maize production.

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 five Bacillus species (B. polymyxa, B. pantothenticus, B. anthracis, B. thuringiensis, and B. circulans), three Pseudomonas species (P. cichorii, P. putida, and P. syringae), and Serratia 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. All Serratia strains (100%) have produced ammonia, whereas 80% of Bacillus and 77.77% of Pseudomonas produced 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.

The aim of the study was to investigate the effects of five plant growth-promoting rhizobacteria (PGPR) (Bacillus panthothenicus; Pseudomonas Cichorii; Pseudomonas Putida; Pseudomonas syringae and Serratia marcescens) on the growth and yield of maize on a ferruginous soil under field condition. Maize seeds were inoculated with 10 ml of bacterial suspension. Study was conducted in a completely randomized design with fifteen treatments and three replicates. A half-dose of recommended (13, 17, 17 kg•ha −1) NPK was applied 15 days after emergence. The results show that the Serratia marcescens + 50% NPK treatment yielded the best results for height, fresh underground biomass, dry aboveground biomass, dry underground biomass, and grain yield with respective increases of 41.09%, 217.5%, 213.34%, 93.82%, and 39.05% compared to the control. Maximum stem diameter (increases of 49.65%) was recorded in the plants treated with 100% NPK (full dose NPK) while the highest leaf area (466.36 ± 9.57 cm 2), obtained on plant treated with Pseudomonas putida + 50% NPK was 32.08% greater than in the non-inoculated control. Our results suggest the use of these rhizobacteria as biological fertilizers for enhancing the growth and maize seed yield in ferruginous soil in the North of Benin.

Maize plays a vital role in Benin's agricultural production systems. However, at the producer-level, yields are still low, although the production of this cereal is necessary for food security. The aims of this study were to assess the efficacy of solid biostimulants formulated from the rhizobacteria Pseudomonas putida and different binders on maize cultivation in the farming environment in three (03) study areas in South Benin. For this purpose, three (03) biostimulants were formulated based on Pseudomonas putida and the clay, peat and clay-peat combinations binders. The experimental design was a randomized block of four (04) treatments with 11 replicates per study area. Each replicate represented one producer. The trials were set up at 33 producers in the study areas of Adakplamè, Hayakpa and Zouzouvou in Southern Benin. The results obtained show that the best height, stem diameter, leaf area as obtained by applying biostimulants based on P. putida and half dose of NPK and Urea with respective increases of 15.75, 15.93, and 15.57% as compared to the full dose of NPK and Urea. Regarding maize yield, there was no significant difference between treatments and the different study areas. Taken together, the different biostimulants formulations were observed to be better than the farmers' practice in all the zones and for all the parameters evaluated, with the formulation involving Pseudomonas putida on the clay binder, and the half-dose of NPK and Urea showing the best result. The biostimulant formulated based on clay + Pseudomonas putida could be used in agriculture for a more sustainable and environmentally friendly maize production in Benin.

The attainment of the millennium for development objectives require to improve the productivity of major cultures like maize (Zea mays L.). The present study aimed to assess the potential of Glomus cubens, Rhizophagus intraradices and Funneliformis mosseae to improve the productivity of corn cultivated on reddish ferrous soil in Southern Benin. A block of nine treatments with four repetition completely randomized was installed. Plant height and diameter and leaf area are growth parameters measured. Grain yield and endomycorrhizal infection were also evaluated. The best growths and grain yield (2.33 t/ha and 2.12 t/ha) were obtained respectively with the plants treated with R. intraradices + 50% of NPK and G. cubens + 50% of NPK compared to the control plants (1.48 t/ha). Moreover, the great frequencies of mycorhization (44% and 32.25% were observed respectively on the plants treated with G. cubens + 50% of NPK and R. intraradices + 50% NPK. These results show that the respective combination of these two Arbuscular Mycorrhizal Fungi with 50% NPK can increase of 50% the seeds yield of corn compared to the seeds yield obtained with the control plants. In addition, G. Cubens and R. intraradices are active in the colonization of maize roots. Use of R. Intraradices or G. cubens in combination with 50% of NPK help to increase the corn productivity and to reduce of half the chemical fertilizer commonly used by corn farmers at Southern Benin.

KEYWORDS ABSTRACTThe aim of this study was to assess the combined effects of the three plant growth promoting Rhizobacteria (Azospirillum lipoferum, Pseudomonas fluorescens and Pseudomonas putida) and a biostimulating molecule (chitosan) on plant growth parameters and seeds yield of maize in southern Benin. This study was conducted in reddish ferrous soil with fisher block experimental design. Maize seeds were soaked into chitosan solution for 12 hours and introduced into a seed hole with bacterial suspension. Experimental maize plants were fertilized by half or complete dose of NitrogenPhosphorus-Potassium (NPK) and Urea. Result of the study revealed that the combination of P. fluorescens along with chitosan and half dose of NPK-Urea increased maize height, circumference and seeds yield of 10.18%, 22.05% and 44.10% respectively. Furthermore, the produced biomass increased 71.43% compared to the control in the combination of P. fluorescens, chitosan and complete dose of NPK-Urea. Results of study suggesting that PGPR and chitosan can be used as an effective biological fertilizer combination for increasing maize production under field conditions.

The application of biostimulants in agriculture represents an environmentally friendly alternative while increasing agricultural production. The aims of the study were to develop solid biostimulants based on five rhizobacteria native to Benin's soils and to evaluate their efficacy on the growth and biomass yield of maize under greenhouse conditions on ferrallitic and ferruginous soils. Clay and peat were used as a conservation binder for the preparation of the biostimulants. These binders were used alone or combined in the different formulations with maize flour and sucrose. 10 g of biostimulants were applied at sowing in pots containing five kilograms of sterilised soil. The experimental design was a completely randomised block of 24 treatments with three replicates. The results obtained showed significant improvements (P < 0.001) in height (49.49%), stem diameter (32.7%), leaf area (66.10%), above-ground biomass (97.12%) and below-ground biomass (53.

Plant growth promoting rhizobacteria (PGPR) are known to influence plant growing both by direct and/or indirect mechanisms. This study aimed to establish PGPR profile of 15 bacteria isolated from maize (Zea mays L.) rhizosphere in Benin. These rhizobacteria were screened in vitro for the plant growth promoting traits like production of indole acetic acid (IAA), ammonia (NH 3), hydrogen cyanide (HCN), catalase, exopolysaccharides and antifungal activity against phytopathogenic fungi for example Fusarium verticillioides, that is an important maize pathogenic. Most rhizobacteria strains were found to produce catalase (100%), exopolysaccharides (100%), ammonia (86.66%), hydrogen cyanide (80%) and indole acetic acid (60%). Pseudomonas putida, Pseudomonas fluorescens and Azospirillum lipoferum have highly produced many of the investigated metabolites. Streptomyces hygroscopicus, Streptomyces fasciculatus, Pseudomonas aeruginosa, P. putida, P. fluorescens and A. lipoferum inhibited mycelial growth of F. verticillioides and Aspergillus ochraceus. P. fluorescens and P. aeruginosa were highly antagonistic against F. verticillioides (52.24% of mycelial growth inhibition) and A. ochraceus (58.33% of mycelial growth inhibition). These results suggest the possibility to use these rhizobacteria as biological fertilization to increase maize yield and the biological control of F. verticillioides and A. ochraceus.