Plant Growth–Promoting Potential of Endophytic Bacteria Isolated from Asparagus racemosus Willd and their role in improving Chickpea (Cicer arietinum L.) Germination

Abstract Endophytic bacteria inhabiting internal plant tissues are increasingly recognized for their role in enhancing plant growth and stress tolerance. The present study investigated the plant growth-promoting potential of root-associated endophytic bacteria isolated from the medicinal plant Asparagus racemosus Willd. and evaluated their effect on seed germination of desi chickpea ( Cicer arietinum L.). Healthy tuberous roots were surface sterilized, and endophytic bacteria were isolated using standard microbiological techniques. Seven morphologically distinct bacterial isolates were obtained and characterized through morphological, biochemical, and molecular approaches. The isolates were screened for important plant growth-promoting traits including indole-3-acetic acid (IAA) production, phosphate solubilization, nitrogen fixation, siderophore production, ammonia production, hydrogen cyanide production, ACC deaminase activity, and extracellular hydrolytic enzymes. Among the isolates, strain AR1 exhibited the most comprehensive PGP profile, showing positive responses for IAA production, phosphate solubilization, nitrogen fixation, siderophore production, ACC deaminase activity, and multiple hydrolytic enzymes. Molecular identification based on 16S rRNA gene sequencing revealed that AR1 belonged to Enterobacter wuhouensis , while amplification of the nifH gene confirmed its nitrogen-fixing potential. Seed inoculation experiments demonstrated a substantial enhancement in chickpea germination, with inoculated seeds achieving 85.19% germination compared to 29.63% in uninoculated controls. Enhanced radicle growth and seedling vigor were also observed. These findings highlight A. racemosus as a valuable reservoir of beneficial endophytic bacteria and demonstrate the potential of strain AR1 as a bioinoculant for sustainable crop production. Further investigations involving whole-genome sequencing, transcriptomic analyses, and multilocation field evaluations are warranted to validate its agricultural applicability under diverse environmental conditions.