THULASI BAI VADITHE, SEVA NAYAK DHEERAVATHU, SRINIVASAN R., SRINIVAS A., KETHAVATH MADHUDEEPIKA, SRAVANTHI G., SAIDA NAIK VADITHE, BANDEPPA S. AND A. JYOTHI
ICAR-Indian Institute of Millets Research, Hyderabad-500030 (Telangana), India
Department of Crop Physiology, Agricultural College, Bapatla-522101 (Andhra Pradesh), India
ICAR-Indian Grassland and Fodder Research Institute, Jhansi-284003 (UP), India
ANGRAU-Agricultural Research Station, Jangameswarapuram, Palanadu-522415 (Andhra Pradesh), India
Indian Institute of Rice Research, Hyderabad-500030 (Telangana), India
Department of Microbiology, Visakha Government Degree College for Women (A)
Visakhapatnam-530020 (Andhra Pradesh), India
*(e-mail: sevanayak2005@gmail.com)
(Received : 9 September 2025; Accepted : 29 September 2025)
SUMMARY
Microorganisms are indispensable for sustainable agriculture, as they perform multiple vital functions within the soil–plant ecosystem. They influence soil fertility, crop productivity, and plant health through diverse ecological and biochemical processes. In agricultural systems, microbes act as natural fertilizers, biocontrol agents, and soil engineers, thereby maintaining the balance and productivity of agroecosystems. By facilitating nutrient cycling, decomposing organic matter, and enhancing plant resilience, microorganisms significantly reduce dependence on chemical fertilizers and pesticides. This not only minimizes environmental pollution but also promotes eco-friendly and sustainable farming practices. Among beneficial microorganisms, Plant Growth-Promoting Bacteria (PGPB) represent a distinct group capable of colonizing plant roots and improving overall plant performance. PGPB exert their beneficial effects through both direct and indirect mechanisms: Direct mechanisms: Biological nitrogen fixation, Phosphate solubilisation, Phytohormone production (auxins, cytokinins, gibberellins), Mobilization of essential nutrients. Indirect mechanisms: Suppression of pathogens through antibiotic production and competition, Siderophore production for iron acquisition, Induction of systemic resistance against various biotic stresses, Mitigation of abiotic stresses such as salinity, drought, and heavy metal toxicity. In this review, we discuss the various direct and indirect mechanisms employed by PGPB that contribute to plant growth, soil health, and sustainable crop production.
Key words: Plant Growth-Promoting Bacteria (PGPB), Biological nitrogen fixation, Phosphate solubilisation Phytohormone, abiotic stress and Biological Nitrogen Fixation (BNF)