Lanthanum Silicate Nanomaterials Enhance Sheath Blight Resistance in Rice: Mechanisms of Action and Soil Health Evaluation

In the current study, foliar spray with lanthanum (La) based nanomaterials (La 10 Si 6 O 27 nanorods, La 10 Si 6 O 27 nanoparticle, La(OH) 3 nanorods, and La 2 O 3 nanoparticle) suppressed the occurrence of sheath blight ( Rhizoctonia solani ) in rice. The beneficial effects were morphology-, composition-, and concentration-dependent. Foliar application of La 10 Si 6 O 27 nanorods (100 mg/L) yielded the greatest disease suppression, significantly decreasing the disease severity by 62.4% compared with infected controls; this level of control was 2.7-fold greater than the commercially available pesticide (Thifluzamide). The order of efficacy was as follows: La 10 Si 6 O 27 nanorods > La 10 Si 6 O 27 nanoparticle > La(OH) 3 nanorods > La 2 O 3 nanoparticle. Mechanistically, (1) La 10 Si 6 O 27 nanorods had greater bioavailability, slower dissolution, and simultaneous Si nutrient benefits; (2) transcriptomic and metabolomic analyses revealed that La 10 Si 6 O 27 nanorods simultaneously strengthened rice systemic acquired resistance, physical barrier formation, and antioxidative systems. Additionally, La 10 Si 6 O 27 nanorods improved rice yield by 35.4% and promoted the nutritional quality of the seeds as compared with the Thifluzamide treatment. A two-year La 10 Si 6 O 27 nanorod exposure had no effect on soil health based on the evaluated chemical, physical, and biological soil properties. These findings demonstrate that La based nanomaterials can serve as an effective and sustainable strategy to safeguard crops and highlight the importance of nanomaterial composition and morphology in terms of optimizing benefit.