Abstract

The increasing global population and the concurrent rise in competition for limited water resources necessitate a substantial increase in food production by 2050. Climate change, characterized by altered rainfall patterns and frequent droughts, poses significant challenges to agricultural productivity. This chapter explores the potential of bio-inoculants, specifically plant growth-promoting microorganisms (PGPM) such as bacteria, free-living fungi, and arbuscular mycorrhizal fungi (AMF), in mitigating drought stress in crops. Bio-inoculants can enhance plant tolerance to water deficit through various mechanisms, including the production of growth-regulating substances, osmolytes, exopolysaccharides, and volatile organic compounds. These microorganisms also facilitate nutrient solubilization and uptake, which is crucial under drought conditions. Bacteria, particularly those capable of producing 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, play a pivotal role in reducing ethylene levels in plants under stress, thus promoting growth. The chapter emphasizes the need for further research into the mechanisms exerted by free-living fungi and the potential benefits of microbial consortia. The integration of bio-inoculants with conventional drought mitigation strategies, such as plant breeding and the exogenous application of substances, could provide holistic solutions to enhance crop resilience against drought in the context of climate change. © CAB International 2025.