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.