Nitrogen fertilizer improves <i>Salix matsudana</i> growth and soil qualities.

Abstract

<h4>Introduction</h4>Soil contamination with heavy metals (e.g., Pb, Cd) poses severe environmental risks due to industrialization. <i>Salix matsudana</i>, a metal-tolerant woody plant, shows promise for phytoremediation, yet the synergistic role of nitrogen (N) fertilization in enhancing plant growth and soil remediation remains unclear. This study aims to elucidate how N fertilization optimizes <i>S. matsudana's</i> remediation efficiency.<h4>Methods</h4>We applied integrated physiological and multi-omics approaches to assess N fertilization effects on <i>S. matsudana</i> growth, Pb/Cd uptake, and rhizosphere properties. Physiological metrics (biomass, metal accumulation) were combined with microbial community analysis (16S rRNA sequencing) and metabolomic profiling (LC-MS/GC-MS) of rhizosphere soils under varying N concentrations.<h4>Results</h4>High N levels significantly increased plant biomass and Pb/Cd accumulation. Microbial diversity shifted, with enriched metal-mobilizing taxa. Metabolomics revealed elevated organic acids, correlating with improved metal bioavailability and soil health.<h4>Discussion</h4>N fertilization synergistically enhances phytoremediation by: (1) stimulating plant growth and metal uptake, (2) reshaping rhizosphere microbiomes for metal mobilization, and (3) promoting chelating metabolite secretion. These findings provide actionable insights for optimizing N-assisted phytoremediation strategies.