Silicon Dioxide Nanoparticles and Biochar to Suppress Leaf Blight and Fruit Rot in Eggplant

Leaf blight and fruit rot caused by Phomopsis vexans are critical issues for eggplant crops. Our study evaluated the biochar amendment, alone and in combination with a foliar spray of silicon dioxide nanoparticles (SiO2-NPs), on plant performance and disease development. Fungal infection reduced plant growth, with a 22% decline in plant height and a marked decrease in chlorophyll and carotenoid levels. Adding biochar plant height mitigated these effects: the highest dose (30 g) increased plant height in infected plants by 17.1% and increased pigment concentrations and POX and PPO activities. At the same time, the blight index declined. When biochar was combined with SiO2-NPs, the improvements were more pronounced. In infected plants, the 30 g + SiO2-NPs treatment produced substantial improvement in plant height (+31.3%) and shoot biomass and restored chlorophyll and carotenoid contents by 63% and 28.1%, respectively. This treatment also produced the lowest blight index and the strongest enzymatic responses. Principal component analyses discriminated treated plants from infected ones. These findings indicate that biochar and SiO2-NPs can jointly enhance plant resilience to P. vexans infection, reducing its negative impact.