Journal of Agronomy and Field Innovations

Background: Plant growth-promoting rhizobacteria (PGPR) are increasingly recognized as sustainable alternatives to chemical fertilizers in cereal production. Among these, Paenibacillus polymyxa is notable for its multifunctional plant growth-promoting (PGP) traits and broad-spectrum antagonism against phytopathogens.
Objective: This study aimed to isolate and functionally characterize a P. polymyxa strain from wheat rhizosphere soil and evaluate its growth-promoting potential under greenhouse conditions.
Methods: Rhizosphere soil was sampled from healthy wheat fields, and bacteria were isolated on nutrient agar, purified, and identified by morphological, biochemical, and 16S rRNA gene sequencing analyses. PGP traits, including IAA production, phosphate and potassium solubilization, nitrogen fixation, siderophore and ammonia production, HCN production, ACC deaminase activity, and biofilm formation, were quantified. Antagonism against wheat phytopathogens and a pot-based plant growth assay were also performed, with data analyzed by one-way ANOVA and Tukey's test.
Results: The isolate, designated WR-7, was confirmed as P. polymyxa with 99.1% 16S rRNA sequence similarity to reference strains. It produced substantial IAA (28.4 µg/mL), solubilized phosphate (312 µg/mL) and potassium, fixed atmospheric nitrogen, and generated siderophores, ammonia, and biofilm. Inoculation significantly (p<0.05) improved germination percentage, root and shoot length, biomass, and chlorophyll content relative to untreated controls, and inhibited three major phytopathogens in vitro.
Conclusion: P. polymyxa WR-7 exhibits robust, multifaceted plant growth-promoting activity and represents a promising candidate biofertilizer for sustainable wheat cultivation, warranting further field-scale validation.