Nano-formulated prothioconazole seed coating improves rice bakanae control and seedling establishment via metabolome and respiration modulation

Rice bakanae disease, caused by Fusarium fujikuroi that infects plants by colonizing the seed coat or embryo, poses a significant threat to rice production. While seed treatment with flowable concentrate (FS) of fungicides effectively controls rice bakanae, they may also pose phytotoxic risks. In this study, a reactive oxygen species (ROS)-generating prothioconazole nano-flowable concentrate (PROT NFS, 172.56 nm) for seed coating was prepared using wet media milling. The uptake and translocation test showed that after 21 days of PROT NFS seed treatment, prothioconazole levels in rice reached 10.43 mg/kg in roots and 1.89 mg/kg in leaves, accounting for an increase of 64.79 % and 137.65 %, respectively, compared to the PROT FS treatment. Consequently, the efficacy of disease control was improved, increasing from 60.72 % (PROT FS) to 85.71 % (PROT NFS). The ASTEC values from the Q2 seed vigor test indicated that PROT NFS exhibited similar metabolism time (24.81 h), relative germination time (65.41 h), starting metabolism rate (1.07 %/h), and oxygen consumption rate (1.90 %/h) compared to the bare seed treatment. Metabolomics analysis showed that the PROT NFS mitigated the pesticide damage of the traditional FS on rice seedlings and promoted seed vigor responses. Furthermore, PROT NFS was found to be biologically safe for non-target organisms. Thus, this study presents a promising strategy for enhancing seedling health through PROT NFS. • The preparation process is suitable for large-scale industrial production of nanopesticides. • PROT NFS was used for effective delivery of fungicides and improve seed coverage. • PROT NFS accelerated radicle emergence through the seed coat and preserved seed viability. • Nanoparticles provide better control of Fusarium fujikuroi and promote seedling growth. • PROT NFS showed a dual-mode synergistic effect for seed disease management.