Pushpa Gehlot, Jyoti Yadav, Tripta Jain
Agricultural sustainability is increasingly threatened by the excessive use of chemical fertilizers, which has led to soil degradation, nutrient imbalance, and ecological disturbances, necessitating the development of eco-friendly alternatives. Biofertilizers based on plant growth-promoting microorganisms (PGPM), particularly plant growth-promoting rhizobacteria (PGPR) and plant growth-promoting fungi (PGPF), have emerged as promising tools for enhancing crop productivity while maintaining soil health. Chilli ( Capsicum annuum L.), an economically important spice crop, is often constrained by nutrient deficiencies, declining soil fertility, and disease pressure, which significantly affect its yield and quality. This review critically examines current advances in the mechanistic and functional roles of PGPR and PGPF in sustainable chilli cultivation, with particular emphasis on microbial-mediated nutrient mobilization, including nitrogen fixation, phosphate solubilization, phytohormone production, enzymatic activities, and biocontrol mechanisms. Emerging evidence suggests that microbial consortia involving bacterial and fungal inoculants establish synergistic interactions that enhance nutrient availability, improve root architecture, and increase plant tolerance to biotic and abiotic stresses more effectively than single inoculants. Additionally, microbial traits such as siderophore production, and antagonistic potential further contribute to enhanced plant growth, nutrient-use efficiency, and yield stability. Particular attention is also given to recent developments in consortium-based biofertilizer formulations, including carrier selection, inoculant stability, microbial survival, and field-level applicability. Collectively, the available literature indicates that integrated PGPR-PGPF biofertilizer approaches represent a promising strategy for improving chilli productivity, reducing dependency on chemical fertilizers, and promoting long-term soil health and sustainable agricultural resilience.