Plant Growth-Promoting Rhizobacteria (PGPR) as a Biotechnological Tool for Enhancing Cropping Systems and Promoting Sustainable Agriculture

The excessive utilisation of pesticides and chemical fertilizers in modern agriculture generates major problems for the environment, human health and soil quality. In this context, European policymakers, researchers, and farmers are increasingly focusing on alternative solutions that contribute to more sustainable agriculture. Plant growth-promoting rhizobacteria (PGPR) are regarded as biotechnological tools that align well with environmentally friendly alternatives. Numerous PGPR strains are being studied as an ecological alternative to environmentally harmful synthetic preparations (chemical fertilizers, pesticides) and tested for introduction into crop technologies under different formulations, in order to optimize plant growth and improve the production yield. These highly beneficial bacteria colonize on plant roots, stimulating their development through direct and indirect mechanisms. PGPR can improve nutrient availability (nitrogen fixation, phosphorus, potassium, zinc solubilization, etc.) and can influence optimal plant development by producing siderophores and regulating phytohormones. PGPR have the capacity to change the potential for water transport and absorption by roots. Additionally, they can contribute to plant protection by inhibiting pathogens or by stimulating host defence mechanisms, including the production of antibiotics, antioxidants, hydrolytic enzymes, exopolysaccharides, volatile organic compounds (VOCs), and osmotic balancing. The paper provides an overview of the current knowledge regarding PGPR and their importance to enhancing crop productivity and promoting sustainable agricultural practices.