A Malian native plant growth promoting Actinomycetes based biofertilizer improves maize growth and yield

occupies an important place in agricultural production systems in the agro-ecological zones of Mali. It is one of the main cereals involved in the diet of populations in Africa. Although maize is a food crop, it is also a cash crop. In Mali, maize production results have led to a decline in soil fertility and increased numbers of plant pests and diseases. To minimize these negative impacts, farmers have turned to chemical fertilizers and pesticides that are harmful to farmers, consumers, and the environment. Soil organic matter and soil microorganisms are recognized by many researchers as key factors in maintaining crop productivity. Among the microorganisms used as biofertilizers, there is a group of bacteria called Plant Growth Promoting Rhizobacteria (PGPR). These bacteria promote the growth of plants and protect them against pathogens. They are also known to actively colonize plant roots and improve their growth and yield. Numerous attempts have been made to replace harmful chemical fertilizers with biofertilizers in order to obtain a high quantity and quality yield. This study aims to formulate an efficient and low-cost biofertilizer using PGP-Actinomycetes to improve maize growth and yield in Mali. To achieve this goal, six strains of Actinomycetes (H7, H17, S24, R13, T57, and O19) were selected from the collection of the Laboratory of Microbiology and Microbial Biotechnology (LaboREM-Biotech) of the Faculty of Science and Technology/University of Science, Technology, and Technology of Bamako. These Actinomycetes have been isolated and characterized. The selected Actinomycetes were evaluated for their ability to solubilize phosphorus, fix atmospheric nitrogen, and produce antimicrobial substances, enzymes, phytohormones, and siderophores. The results showed that Actinomycetes sp. H7 was the most effective in solubilizing phosphorus, with a solubilization index (SI) of 80%. This strain was also found to be highly effective in fixing atmospheric nitrogen and producing indole acetic acid (IAA). The production of siderophores was also observed in Actinomycetes sp. H7. The antibacterial activity of the selected Actinomycetes was determined using the method described by Babana et al. (2011). The results showed that Actinomycetes sp. H7 had the highest antibacterial activity, with a diameter of inhibition zone of 20 mm. The antifungal activity of the selected Actinomycetes was determined using the double layer method. The results showed that Actinomycetes sp. H7 had the highest antifungal activity, with a diameter of inhibition zone of 25 mm. In greenhouse experiments, the inoculated seeds with Actinomycetes sp. H7 showed the best growth in plant size, with a 19.3% increase compared to the uninoculated control. In station experiments, it was found that Actinomycetes sp. H7 significantly increased the fresh and dry biomass of the aerial part, with 919.7 g and 405.6 g, respectively, against 636.70 g and 297.36 g, respectively, for the control. The best yield of seeds was obtained with the combination O19-AHB12, with a yield of 311.5 g for 1000 seeds compared to 178.28 g for the uninoculated control. These results confirm the value of the PGPRs and open a way for the formulation and use of biofertilizers based on PGPRs in Mali.