Species interactions and bacterial inoculation enhance plant growth and shape rhizosphere bacterial community structure in faba bean – wheat intercropping under water and P limitations.

Grain legumes / cereals intercropping systems with microbial inoculants, hold promise for improving crop productivity under stressful conditions. However, the tripartite interaction involving intercropping system, associated microbiota and stress combining water deficit and low phosphorus (P) availability remains understudied. This study evaluated the impact of three bacterial consortia (C 4 , C 6 , and C ref containing Rhizobium and PSB strains) including single Rhizobium (Rhizobium laguerreae) on the agro-physiological performance of wheat (Triticum durum) and faba bean (Vicia faba) grown as intercrops or sole-crops under P and water deficient conditions. Inoculation, especially with C 6 , significantly improved shoot and root biomasses of both wheat (up to 66 and 81 %) and faba bean (up to 54 and 266 %) intercrops compared to single Rhizobium inoculation and control treatments. Intercropping generally outperformed sole-cropping in above-ground physiology, root morphological traits, shoot and root P content, with a notable effect in response to C 6 exhibiting low microbial biomass P. Changes in bacterial community structure were primarily driven by cropping pattern and water regime rather than bacterial inoculation. Intercropping maintained bacterial diversity but shifted community structure, favoring Proteobacteria. Overall, inoculating intercropped wheat and faba bean with Rhizobium -containing consortia induced beneficial below-ground interspecies interactions under water and P-limiting conditions. • Rhizobium-containing bacterial consortia enhanced belowground interactions in wheat/faba bean intercrops. • Inoculation enhanced root traits and phosphorus dynamics in rhizosphere soil of both intercropped wheat and faba bean plants. • Water regime and cropping pattern rather than inoculation drove shifts in bacterial community structure. • Bacterial consortia enhanced growth performance of intercropping over sole cropping under low P-availability. [ABSTRACT FROM AUTHOR]