Entire Journey of Foliar Applied Nanomaterials with Different Surfactants Modification on Tomato Leaves and Subsequent Modulation of Stress Resistance

Foliar application of nanomaterials (NMs) offers great potential for sustainable crop disease management. However, how the presence of surfactants alters the behavior of NMs on leaf surfaces and their subsequent modulation of disease resistance remains unclear. Here, surfactants were incorporated into NMs suspensions to enhance foliar adhesion and deposition, thereby suppressing early blight (Alternaria solani) in tomato. Nonionic surfactants (Tween-80 and Silwet L-77) significantly improved the foliar deposition and translocation of La10Si6O27 nanorods (NRs). The treatment combining La10Si6O27 NRs with Silwet L-77 (NRs + L77) achieved the highest efficacy, reducing disease severity by 70%, which is 19.99% higher than La10Si6O27 NRs alone treatment. Mechanistically, (1) NRs + L77 activated the antioxidant defense system, increasing superoxide dismutase and peroxidase activities by 21.22% and 140.10%, respectively, while decreasing malondialdehyde content by 28.72%; (2) NRs + L77 optimized the phyllosphere microbiome, enriching beneficial genera such as Bacillus, Pantoea, and Klebsiella and restoring microbial network complexity; and (3) NRs + L77 upregulated defense-related gene expression, activated phenylpropanoid and flavonoid metabolic pathways, and induced systemic acquired resistance. In addition, NRs + L77 exhibited favorable biosafety toward nontarget organisms. This study demonstrates the potential of surfactant-modified NMs in improving disease control efficiency and contributing to sustainable crop protection.