Harnessing Soil Microbes to Modulate Plant-Soil Feedbacks in Saline Agricultural Systems

Abstract

Soil salinity is a major constraint to agricultural productivity, causing osmotic stress, ion toxicity, nutrient imbalance, and progressive deterioration of soil biological functions. Beyond its direct effects on plant performance, salinity also generates persistent soil legacies that influence subsequent plant growth through plant-soil feedback (PSF) processes. PSF provides an ecological framework for understanding how plants modify the physicochemical and biological properties of soil and how these altered soil conditions subsequently affect plant growth, health, and resilience. Salinity research has predominantly emphasized soil microorganisms as promoters of plant growth, while their broader role in regulating soil legacy effects remains comparatively underexplored. This review examines whether soil microorganisms may contribute to a transition from salt-amplified negative PSF toward more favorable feedback outcomes by reshaping rhizosphere chemistry, nutrient cycling, pathogen pressure, ion homeostasis, stress signaling, and soil structural stability. However, conditioned-soil bioassays and multi-season saline field trials remain scarce, these proposed pathways are treated as potential mechanisms or testable hypotheses rather than as established evidence of PSF regulation. We first summarize the mechanisms underlying PSF in non-saline systems and then describe how salinity alters plant-, soil-, and microbe-mediated feedback pathways. We further evaluate the potential of halotolerant plant growth-promoting rhizobacteria, arbuscular mycorrhizal fungi, actinobacteria, disease-suppressive microbial communities, and synthetic microbial consortia as regulators of PSF, while distinguishing direct salt-tolerance effects from evidence of genuine feedback modulation. Specifically, improved salt tolerance in the inoculated plant is interpreted as direct stress mitigation, whereas demonstrated PSF regulation additionally requires measurable soil conditioning and an effect on a subsequent crop. The novelty of this review lies in organizing studies of salinity-microbiome interactions within an evidence-based PSF framework that differentiates immediate plant responses from rhizosphere modification, conditioned-soil effects, and subsequent-crop performance. The review concludes that microbial strategies for saline agriculture are most likely to succeed when developed as integrated PSF interventions that combine crop traits, indigenous microbiomes, optimized inoculant design, organic matter management, diversified rotations, and multi-season field validation.