Nanopriming for Sorghum Resilience: Green-Synthesized SiO2 and ZnO Nanoparticles Cooperatively Activate Defense Responses and Improve Seedling Establishment against Head Smut

Abstract

Green-synthesized SiO2 and ZnO nanoparticles prepared using Moringa oleifera leaf extract were evaluated as individual and combined seed-priming treatments against sorghum head smut. Antifungal assays included a commercial fungicide control; pot measurements covered disease, growth, photosynthesis, defense enzymes, phytohormones, and mineral nutrition. The respective EC50 values for SiO2, ZnO, and their 1:1 mixture were 75.4, 42.3, and 28.7 mg L–1. Combined priming at 50 + 50 mg L–1 produced a disease index of 6.5, compared with 50.8 in the infected control, giving 87.2% control efficacy. Disease outcomes did not differ significantly from the fungicide treatment under the reported comparison. The combined treatment also increased seedling growth and defense-related responses. These observations support further evaluation of the formulation as a multifunctional seed treatment under natural soil and field conditions.