Plant–Microbiome Interactions in Agriculture: From Rhizosphere Biology to Crop Health and Productivity

Plant-associated microbiomes influence nutrient acquisition, development, immune regulation and responses to environmental stress, yet their deliberate management in agriculture remains less predictable than mechanistic studies imply. This critical narrative review integrates ecological assembly theory, host–microbe signalling, disease-suppressive microbiomes, nutrient symbioses and agronomic intervention evidence, with particular attention to the gap between controlled experiments and field performance. Peer-reviewed research and critical syntheses published principally between 2012 and 10 August 2026 were identified through accessible scholarly resources and cross-checked against bibliographic and DOI records. Evidence indicates that soil legacy, host genotype, root chemistry, microbial interactions and management jointly govern rhizosphere membership, but taxonomic enrichment alone does not establish a benefit to crops. Strong mechanistic demonstrations link selected microbial consortia with suppression of pathogens or altered developmental signalling, while field studies and meta-analyses suggest potentially useful average responses to bioinoculation with substantial context dependence. Root symbioses are comparatively well understood, although their marginal benefit depends on available nutrients and resident symbionts. Evidence for microbiome-mediated tolerance of drought and other abiotic stresses is biologically persuasive but often rests on compositional shifts, short-duration assays or insufficiently replicated field conditions. The review proposes a causal and agronomic evidence framework that distinguishes microbial presence, functional expression, plant benefit and durable farm-level value. Priority research needs include factorial multi-environment trials, strain-resolved persistence measurements, plant–soil–microbe mechanisms, transparent negative-result reporting and assessments of profitability and ecological safety. Microbiome-centred strategies are best treated as context-sensitive complements to sound soil and crop management rather than universal substitutes for agricultural inputs.