Biogenic Nanoparticles and Nanobiochar for Rhizosphere Engineering in Salinity-Resilient Agriculture: A Review

Abstract

Soil salinization remains a major constraint to sustainable crop production because it disrupts soil structure, root function, nutrient availability, ion homeostasis, oxidative balance and rhizosphere microbial activity. Conventional salinity-management practices often provide only partial relief because they do not fully address the linked chemical, physical, biological and hydraulic processes operating at the soil-plant-microbiome interface. This review examines the potential role of biogenic nanoparticles, biochar and engineered nanobiochar systems in rhizosphere engineering for salinity-resilient agriculture. Biogenic nanoparticles may support salt-stress adaptation by influencing ion transport, antioxidant defense, osmotic adjustment, photosynthetic performance, nutrient acquisition, phytohormonal signalling and root-associated microbial processes. Biochar may complement these responses through sodium retention, improved porosity and water-holding capacity, nutrient buffering, microbial habitat formation and stabilization of rhizosphere conditions. Engineered nanobiochar systems provide an integrated platform in which nanoparticle reactivity is combined with the structural and adsorptive properties of biochar. The review also considers links with microbiome engineering, multi-omics approaches, artificial intelligence-assisted precision agriculture and climate-resilient soil management. Despite promising evidence from controlled studies, important limitations remain, including particle aggregation under saline conditions, dose-dependent toxicity, uncertain environmental persistence, limited field validation, variable biochar performance and fragmented regulatory frameworks. Overall, nano-enabled rhizosphere engineering is a developing approach that may contribute to salinity resilience when supported by mechanistic validation, biosafety assessment, field reproducibility and responsible deployment.