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 (La₁₀Si₆O₂₇ nanorods, La₁₀Si₆O₂₇ nanoparticle, La(OH)₃ nanorods, and La₂O₃ nanoparticle) suppressed the occurrence of sheath blight (Rhizoctonia solani) in rice. The beneficial effects were morphology-, composition-, and concentration-dependent. Foliar application of La₁₀Si₆O₂₇ 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: La₁₀Si₆O₂₇ nanorods > La₁₀Si₆O₂₇ nanoparticle > La(OH)₃ nanorods > La₂O₃ nanoparticle. Mechanistically, (1) La₁₀Si₆O₂₇ nanorods had greater bioavailability, slower dissolution, and simultaneous Si nutrient benefits; (2) transcriptomic and metabolomic analyses revealed that La₁₀Si₆O₂₇ nanorods simultaneously strengthened rice systemic acquired resistance, physical barrier formation, and antioxidative systems. Additionally, La₁₀Si₆O₂₇ nanorods improved rice yield by 35.4% and promoted the nutritional quality of the seeds as compared with the Thifluzamide treatment. A two-year La₁₀Si₆O₂₇ 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.