Application of ZnO-nanoparticles to manage Rhizopus soft rot of sweet potato and prolong shelf-life

Abstract A reduction in crop spoilage and an increase in shelf-life is the goal of effective disease control methods. This study aimed to assess ZnO-nanoparticles (ZnO-NPs) as a safe, new protectant against Rhizopus soft rot of sweet potato. ZnO-NPs had a fungicidal effect against Rhizopus stolonifer when used at concentrations above 50 ppm. The results showed that tubers treated with ZnO-NPs exhibited fewer fungal populations (1.2 CFU per segment) than those that did not receive the treatment. Tubers infected with Rhizopus stolonifer and treated with ZnO-NPs showed no visible decay for up to 15 days, indicating that ZnO-NPs act as a coating layer on tuber surface. The greatest weight loss after 15 days of storage was reported in infected tubers (8.98%), followed by infected tubers treated with ZnO (6.54%) and infected tubers treated with ZnO-NPs (3.79%). The activity of cell-wall degrading enzymes, α-amylase and cellulase, were significantly increased in both infected tubers and those treated with ZnO, compared to the tubers treated with ZnO-NPs. These results confirm that coating with ZnO-NPs is an effective method of protecting sweet potato tubers from infection, maintaining their quality and increasing their shelf-life for up to 2 months in storage.