Niche-conserved bacterial consortia enhanced maize agro-physiological performance and soil biological P-related traits under low-P conditions

Application of native bacterial consortia (BC) is gaining attention for their plant growth promotion potential through synergistic interactions among functionally diverse microbial species. In this study, thirty-six rhizoplane BC constructed from seven Moroccan maize-growing regions adopting the niche conservatism approach were tested for their ability to improve maize agro-physiological performance. With each region consisting of four zones, 28 intra-zone BC (niche conserved; using isolates from the same zone or rhizoplane), seven inter-zone (different zones within a region), and one inter-regional (global) BC were tested in planta and linked to biochemical and molecular phosphorus (P) cycling properties of the rhizoplane and bulk soils. Results showed that the pqqC gene in bulk soil (involved in P solubilization) was five times more abundant than the phoD gene (involved in P mineralization) in concert with increased acid phosphatase activity and decreased available P in rhizoplane soils. Plant inoculation experiments under controlled conditions revealed that BC enhanced P uptake and use efficiency, with notable contributions from the pqqC and phoD genes under low P conditions. The most significant improvement in plant growth, yield, and rhizosphere/root morpho-physiological P-related traits were obtained with intra-zone BC (10 out of 28) outperforming the inter-zone and global (inter-region) BC. Specifically, intra-zone BC originating from four regions enhanced soil available P and overall plant biomass (shoots “60 %”, roots “23 %”, and shoot height “14 %”) and nutrient acquisition (N, P and K). Moreover, soil properties, bacterial diversity and composition (rhizoplane and bulk) revealed significant correlations and were strongly associated with plant growth and yield traits. In conclusion, enhanced maize growth and nutrient uptake, particularly P, in response to intra-zone BC supports the effectiveness of the niche conservatism approach in constructing potential BC.