Harnessing Plant Growth-promoting Rhizobacteria for Sustainable Maize Production and Protection

Abstract

Maize (Zea mays L.) is a globally important cereal crop, but its productivity is constrained by nutrient deficiencies, soil-borne pathogens and abiotic stresses. Among the major biotic constraints, Fusarium verticillioides causes seed rot, seedling blight, stalk rot and ear rot, resulting in substantial yield and quality losses. Plant growth-promoting rhizobacteria (PGPR) have attracted increasing attention as sustainable biological inputs for improving maize growth and plant health. This review examines the role of PGPR in maize production, with emphasis on nutrient acquisition, disease suppression and stress tolerance. In maize rhizosphere systems, PGPR, including Bacillus, Pseudomonas, Azospirillum, Azotobacter and Enterobacter spp., enhance plant growth through biological nitrogen fixation, phosphate solubilisation, siderophore production and phytohormone synthesis. These activities can improve root architecture, nutrient uptake and biomass accumulation. PGPR also suppress important maize pathogens, particularly F. verticillioides, through competition for nutrients and ecological niches, production of antibiotics and hydrolytic enzymes, secretion of inhibitory volatile compounds and induction of systemic resistance. In addition, PGPR-mediated regulation of 1-aminocyclopropane-1-carboxylate deaminase activity, antioxidant enzymes and biofilm formation can enhance maize tolerance to drought, salinity and other abiotic stresses. Evidence from greenhouse and field studies indicates that PGPR have potential to support maize growth, reduce disease incidence and lessen dependence on chemical fertilisers and pesticides. However, PGPR performance in maize is influenced by bacterial strain, maize genotype, soil properties, environmental conditions and inoculation method. Further maize-specific field validation, stable microbial formulations and integration into locally adapted crop management systems are required for reliable future application in sustainable maize production.