Silica nanoparticles (SiNPs) offer an ecofriendly and environmentally safe alternative for plant disease management. However, the mechanisms of SiNPs-induced disease resistance are largely unknown. This research evaluated the application of SiNPs in controlling the postharvest decay of ginger rhizomes inoculated with Fusarium solani. In vitro study showed that SiNP had little inhibitory effect on mycelial growth and spore germination of F. solani and did not significantly change mycelium’s MDA content and SDH activity. In vivo analysis indicated that SiNPs decreased the degree of decay around the wounds and decreased the accumulation of H₂O₂ after long-term pathogenic infection through potentiating the activities of antioxidant enzymes such as SOD, APX, PPO, and CAT. SiNP150 increased the CHI, PAL, and GLU activity at the onset of the experiment. Moreover, SiNP150 treatment increased total phenolics contents by 1.3, 1.5, and 1.2-times after 3, 5, and 7 days of treatment, and increased total flavonoids content throughout the experiment by 9.3%, 62.4%, 26.9%, 12.8%, and 60.8%, respectively. Furthermore, the expression of selected phenylpropanoid pathway-related genes was generally enhanced by SiNPs when subjected to F. solani inoculation. Together, SiNPs can effectively reduce the fungal disease of ginger rhizome through both physical and biochemical defense mechanisms.

Fusarium solani is one of the most ruinous soil-borne pathogens and seriously affects crop yields and quality worldwide. Ginger is an important medicinal crop, and ginger rhizome extract (GRE) has been used as an alternative for chemical fungicides and bactericides. We investigated the fungistatic effect of GRE on F. solani and analyzed the chemical constituents of GRE using UPLC-MS/MS. Antifungal assay results showed that 20 mg/mL of GRE completely inhibited the growth of F. solani. Morphological analysis revealed that GRE destroyed the morphology and structure of mycelia, thus inhibiting mycelial growth. Furthermore, GRE suppressed the activities of cell wall-degrading and cellular respiratory-related enzymes and decreased the content of fusaric acid, which reduced or even abrogated the infection ability of F. solani. UPLC-MS/MS analysis showed that GRE constituents belonged to eight categories, among which phenolic acids were the highest in content (46.29%) and tannins were the lowest in content (0.06%). When the antifungal activities of major phenolic and flavonoid compounds were evaluated, 4.0 mg/mL 4-hydroxybenzaldehyde and 15.0 mg/mL quercetin were found to completely inhibit F. solani growth. These results highlight GRE as an excellent source of antifungal compounds and suggest the possibility of using 4-hydroxybenzaldehyde and quercetin as natural fungicides to control crop diseases.