Sodium nitroprusside enhances <i>Eichhornia crassipes</i> remediation capacity of eutrophic water bodies through nitric oxide release

Water hyacinth (<i>Eichhornia crassipes</i>) is effective at remediating eutrophic water bodies through nitrogen (N) uptake, but its uncontrolled growth causes oxygen depletion. Sodium nitroprusside (SNP) is known to regulate plant growth and development. Here, the effects of SNP (1 μM and 10 μM, no change in total N levels of water bodies upon treatment with these concentrations of SNP) on N uptake, growth, and N assimilation in water hyacinth were investigated under low, medium, and high eutrophication levels. SNP enhanced the N absorption capacity of water hyacinth roots and upregulated the activities of key enzymes in N assimilation, resulting in elevated levels of free amino acids. This promoted tillering (<i>e.g.,</i> 40% increase in the tiller number) and reduced per-tiller health while simultaneously reducing surface coverage and improving N uptake efficiency, thereby increasing the N demand for plant growth. The application of a nitric oxide (NO) production inhibitor (Carboxy-PTIO) confirmed that SNP regulates N assimilation and tillering in water hyacinth through NO signaling, reducing water surface coverage without compromising N absorption capacity. These results suggest that SNP-mediated NO signaling can optimize the phytoremediation potential of water hyacinth by balancing N removal efficiency with controlled growth.