Microbial Inoculants for Growth and Quality Enhancement of Medicinal and Aromatic Plants

Medicinal plants have bioactive components effective in conventional treatments; similarly, aromatic plants contain essential oils that impart aroma and flavor. The global demand for medicinal and aromatic plants has increased significantly in recent decades. Plant characteristics vary substantially depending on the type of soil in which they are grown, as well as on the cultivation strategies. The excessive use of chemical fertilizers in agricultural production has a deleterious impact on soils’ physical and chemical qualities. The challenges associated with the decline in environmental sustainability caused by the indiscriminate use of chemical fertilizers and pesticides in conventional farming systems could be effectively addressed through organic farming practices. To overcome these challenges, microbial inoculants that encourage plant growth and development have been introduced as an alternative. Microbial inoculants enhance soil health by catalyzing key biochemical cycles, breaking down organic matter, fixing nitrogen, solubilizing phosphorus and other minerals, and producing hormones and exudates that enhance soil structure and nutrient mobility. They also boost secondary metabolite production in plants by stimulating plant's metabolic activities. Microbes play a pivotal role in mitigating biotic and abiotic stresses in plants. The growth traits, yield, essential oil composition, and nutrient content of medicinal and aromatic plants (MAPs) are significantly influenced by the application of microbial inoculants compared to chemical fertilizers. This review provides a detailed account of the current understanding of microbial inoculants, their diverse roles in enhancing MAPs growth and quality, the factors influencing their efficacy, and the prospects for their widespread application. Future research should emphasize on the development of multi-strain consortia to leverage synergistic benefits, advanced omics approaches for deeper molecular insights, and potential genetic engineering techniques to enhance efficacy. A holistic integration of microbial strains, plant genotype, environment, and agronomic practices is essential to realize the full potential of microbial inoculants in sustainable MAP production.