Integrated application of plant growth–promoting rhizobacteria and organic amendments enhances growth and nutrient uptake in maize

Nutrient deficiency is a major constraint to maize production and is commonly addressed using synthetic fertilisers. Sustainable alternatives such as plant growth-promoting rhizobacteria (PGPR) combined with organic amendments offer an eco-friendly strategy to improve nutrient uptake and productivity. In this study, two rhizobacterial isolates were characterised based on biochemical attributes and 16S rRNA gene sequencing and identified as Bacillus cereus (RB-1) and Pseudomonas putida (RB-2). Both isolates exhibited multiple plant growth-promoting traits (PGPTs) including ammonia production, starch hydrolysis, phosphate solubilisation, indole-3-acetic acid synthesis, and siderophore production. The complementary expression of these traits is likely to enhance nutrient availability and root development, thereby contributing to the improved performance observed under co-inoculation. In pot experiments, co-inoculation of the PGPR and a nine-strain bacterial consortium with organic amendments (cow dung and vermicompost) significantly improved seed germination, seedling vigour, and maize growth parameters compared with untreated and fertiliser controls. These improvements were accompanied by increased biomass, higher chlorophyll and carotenoid contents, and enhanced nutrient accumulation (N, P, K, Mg, and Fe) in shoots and roots. A strong positive correlation was observed among fresh and dry shoot and root weights. In summary, these findings indicate that co-inoculation of PGPR with organic amendments enhances maize growth and nutrient uptake under greenhouse conditions and may contribute to more sustainable and eco-friendly nutrient management strategies. • Co-inoculation of Bacillus cereus and Pseudomonas putida improved maize growth. • Organic amendments combined with PGPR increased nutrient uptake in maize. • Combined treatments increased chlorophyll a , chlorophyll b , and carotenoid contents. • PCA and correlation analyses revealed strong associations among growth and nutrient traits. • Integration of PGPR with organic amendments supported maize growth under greenhouse conditions.