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 application of Plant Growth Promoting rhizobacteria as a microbial bio-fertilizers to increase soil fertility and productivity, allows a rational use of chemical fertilizers which makes agriculture sustainable. The aim of this study was to evaluate the effects of the rhizobacteria Pseudomonas putida on the maize productivity in farmer environment. For this purpose, trials were conducted in two Agricultural Development Poles with nine (09) producers equitably distributed in Southern, Central and Northern Benin. The experimental design was a completely randomized block of three (03) treatments (T1: farmer practice; T2: P. putida + ½ recommended dose of NPK and Urea; T3: recommended dose of NPK and Urea) with three (03) repetitions. During sowing, two (2) maize seeds of the 2000 SYNEE-W variety were introduced into a pot and inoculated with 10 ml of bacterial suspensions of 108 CFU/ml concentration. The results showed that the best heights, stem diameters and leaf areas of maize plants were obtained with P. putida + ½ recommended dose of NPK and Urea with the nine (09) producers of the three (03) areas with respective increases of 14.76%; 18.08% and 26.56% compared to the farmer practice. In addition, the results related to yield parameters such as aerial biomass, underground biomass and maize grain yield were better improved with the P. putida + ½ recommended dose of NPK and Urea. The average rates of increase recorded were 42.70%, 38.96% and 77.69%, respectively, compared to farmer practice. In sum, this rhizobacteria can be used as the microbial bio-fertilizers to improve maize productivity in Benin.

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.

Faced with the problems posed by the abusive use of chemical fertilizers and pesticides, it is important to find other alternatives that can guarantee a sustainable and environmentally friendly agriculture. The objective of this study was to evaluate the tolerance of a PGPR (plant growth promoting rhizobacteria) Pseudomonas putida strain to different abiotic stress in in vitro conditions and the synergistic effect of this rhizobacterium in combination with chitosan extracted from crab exoskeletons on the growth of maize in greenhouse conditions. The strain of P. putida was put in culture at different temperatures, pH, and NaCl concentrations to determine its growth. Then, this strain in combination with chitosan extracts were tested for their ability to improve maize growth for 30 days. The results showed that the P. putida strain showed excellent resistance capacities to different salt concentrations, pH, and temperature variations. Moreover, an improvement in plant growth and biomass yield parameters was observed. The highest values of height, diameter, and leaf area were obtained with the plants treated with the combination of chitosan extracted from Cardisoma armatum and P. putida, with increases of 26.8%, 31%, and 55.7%, respectively, compared to the control. This study shows the possibility of using chitosan and rhizobacteria as biostimulants to improve productivity and increase maize yield in a sustainable manner.

The use of biotechnological approaches to increase soil fertility and productivity allows to obtain sustainable agriculture with lesser use of chemical fertilizers. The present study aimed to determine whether the inoculation of Bacillus panthothenicus, Bacillus thuringiensis, Pseudomonas putida, Pseudomonas syringae, or Serratia marcescens combined with reduced doses of NPK (nitrogen, phosphorus, potassium) fertilizer can improve the growth and yield of maize on poor ferruginous soils under field conditions in central Benin. For this purpose, maize seeds of the EVDT 97 STR C1 variety were inoculated with 10 ml suspension of five plant growth-promoting rhizobacteria (PGPR) strains, and the plots were fertilized at seeding with the recommended doses (0, 25, 50, 100%) of 200 kg/ha of NPK and 100 kg of urea for corn cultivation. The study was conducted in a completely randomized design with 3 replicates. The results showed that except for P. syringae , which induced the highest fresh aerial biomass (94.51%) and dry aerial biomass (63.63%), all other parameters were positively improved with inoculation associated with reduced doses of NPK + urea. The best height, leaf area, fresh underground biomass, and grain yield were recorded in response to the application of P. syringae + 50% NPK + urea, with an increase of 26.82, 32.23, 107.57, and 30.64%, respectively, compared to those of the control. The inoculation of seeds with P. syringae + 50% NPK + urea can be considered to be an environmentally sustainable strategy for maize cultivation.

Integrated production in sustainable agriculture aims to improve the efficiency of biological inputs through plant-based bioformulations or microorganisms, which are an excellent source of natural fertilisers. A variety of plant stimulants are increasingly used in crop production for environmentally sustainable agriculture. These products have different names and the designations are confusing. The aim of this work is to clarify what is meant by biofertilizer and biostimulant. A biofertilizer is a bacterial or fungal inoculant applied to plants with the aim of increasing the availability of nutrients and their use by plants, regardless of the nutrient content of the inoculant itself. A plant biostimulant is substance or microorganism applied to plants for the purpose of improving the nutritional efficiency, abiotic stress tolerance and/or quality characteristics of crops, regardless of its nutrient content. By extension, plant biostimulants also refer to commercial products containing mixtures of these substances and/or microorganisms. Plant Growth Promoting Rhizobacteria (PGPR) can be called biofertilisers or biostimulants; PGPR formulations are biostimulants. It can be noted that biofertilisers are included in biostimulants.

The use of microbial technologies in agriculture is rapidly expanding with the discovery of new bacterial strains effective in improving plant growth. In this study, we tested and highlighted the efficacy of PGPR (Plant Growth Promoting Rhizobacteria) alone or in a consortium on maize growth. For this purpose, a greenhouse experiment was carried out in pots containing sterilized ferruginous soil for 30 days. The corn seeds of the EVDT 97 SRT C1 variety were inoculated with bacterial suspensions of concentration 10 8 UFC/ml. The experimental device was a random block of 16 three-repeat treatments. The incidence of PGPR inoculated strains is assessed on the biomass growth and yield parameters of maize. At the end of the trial, the results showed that inoculation stimulated plant growth and development and resulted in a significant increase in the height, diameter at the collar, leaf surface and dry weight of aerial biomass of 20.15%, 21%, 32.77% and 37.73% respectively compared to controls, especially in corn plants inoculated with B. thurengiensis + B. panthéthonicus + S. marcescens and Pseudomonas cichorii + Pseudomonas putida + Pseudomonas syringae. These results show the potential of using these rhizobacteria as biological inoculants to improve maize productivity in Benin.