Plant Growth-Promoting Rhizobacteria (PGPRs) are beneficial microbes that inhabit the rhizosphere. PGPRs stimulates plant growth and health through nutrient acquisition, hormone production, biocontrol of pathogens, and soil improvement^[1]. The dominant species found in rhizospheres are microbes from the genus Azotobacter, Alcaligenes, Arthrobacter, Azospirillum, Rhizobium, Pseudomonas, Bacillus, Serratia, Flavobacterium, Acinetobacter^[2][3]. Genera like Azotobacter, Alcaligenes, Arthrobacter, Azospirillum, Rhizobium, Pseudomonas, Bacillus, Serratia, Flavobacterium, and Acinetobacter each offer unique benefits in agriculture. Azotobacter and Azospirillum fix nitrogen, improving soil fertility and supporting plant growth. Rhizobium enhances nitrogen fixation in legumes, while Pseudomonas and Bacillus provide biocontrol against plant pathogens and promote growth. Arthrobacter and Flavobacterium help in phosphorus solubilization and organic matter breakdown, improving soil health. Serratia and Acinetobacter contribute to pathogen suppression and bioremediation, aiding in the cleanup of soil contaminants. Together, these PGPR species enhance plant health, increase yields, and support sustainable farming practices. The mechanism of action of Plant Growth-Promoting Rhizobacteria (PGPRs) involves several processes that promote plant growth and health. PGPRs can solubilize phosphate, an important nutrient for plant growth^[4]. PGPRs can produce plant growth hormones such as auxins and cytokinins, which stimulate plant growth and development. PGPRs can protect plants against harmful pathogens by producing antibiotics and competing for resources with pathogenic microorganisms^[5]. PGPRs can help plants tolerate drought by increasing the water-use efficiency and reducing water loss through transpiration. Some PGPRs can fix atmospheric nitrogen into a form that can be used by plants, which helps to reduce the need for synthetic fertilizers. PGPRs can produce enzymes that break down organic matter in the soil, making nutrients available for plant uptake. PGPRs stimulate the plant's defense system, inducing a state of systemic resistance. This makes the plant more resistant to disease and stress. Some PGPRs can produce exopolysaccharides (EPS), which improve soil structure and stability. This can enhance soil water-holding capacity, nutrient availability, and aeration, all of which promote plant growth^[6][7][8][9]. PGPRs have gained worldwide importance and acceptance for sustainable agricultural practices. The continuous use of chemicals or synthetic fertilizers reduces soil fertility in the long run and the use of intensive agricultural practices to increase crop yield decreases soil fertility and also has a negative impact on the environment. The use of PGPRs has risen globally over the past few decades^[1]. Continued research on PGPRs is necessary to fully realize their potential as a tool for sustainable agriculture and to identify the most effective strains for specific crops and environmental conditions, leading to more targeted and efficient use of PGPRs in agriculture.
Plant Growth-Promoting Rhizobacteria (PGPR) are gaining popularity in agriculture for their ability to enhance crop growth and reduce the need for chemical inputs. They act as biofertilizers by improving soil health, promoting nitrogen fixation, and making phosphorus more available to plants. PGPR also help protect plants from soilborne diseases by outcompeting harmful pathogens. In addition, they boost plant tolerance to environmental stresses like drought and high salinity, which is increasingly important in regions affected by climate change. These beneficial bacteria are used in seed treatments and inoculants for a variety of crops, such as corn, soybeans, and vegetables. PGPR are becoming a key component of both conventional and organic farming practices, as well as in urban farming and greenhouse production, supporting more sustainable agricultural methods. Berseem (Trifolium alexandrinum) an important forage crop in regions with nutrient-deficient soils, was selected for this study due to its natural association with diverse rhizospheric microorganisms, its high nitrogen-fixing potential, and its role in improving soil fertility. Its natural partnership with soil microorganisms makes it an excellent model for studying the effects of Plant Growth-Promoting Rhizobacteria (PGPR) on growth, nutrient absorption, and stress resilience. This research aims to explore how PGPR can improve the efficiency and sustainability of agricultural practices, offering an eco-friendlier approach to crop management. The present study is aimed to isolate and characterize effective PGPRs from Trifolium alexandrinum (Berseem). Functional characterization was done by Orcinol, Gordon & Weber, and Pikovaskya’s method for rhamnolipid, IAA, and phosphate solubilization, respectively. Further, their efficacy is determined using the pot culture method.