Dragon fruit peel extract mediated green synthesis of silver nanoparticles and their antifungal activity against Colletotrichum truncatum causing anthracnose in chilli

Plant extracts have been used as reducing and stabilising agents to synthesise various metal-based nanoparticles due to their cost-effective and eco-friendly nature. In the present work, a green and environment-friendly method is adopted for synthesising silver nanoparticles (Ag NPs) using a biowaste of dragon fruit (Hylocereus spp.) peel aqueous extract at 80ºC in an alkaline condition. The Ag NPs were characterised through various analytical and microscopic techniques. The UV-Vis spectra of Ag NPs showed a characteristic peak between 400 - 410 nm. Transmission and scanning electron microscopic studies confirmed spherical monodispersed particles with an average size of 7 nm. Energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of silver and silver chloride among the principal elements. The X-ray powder diffraction (XRD) spectra showed the crystalline nature of synthesised silver and silver chloride nanoparticles. The synthesised nanoparticles showed potential antifungal activity against Colletotrichum truncatum spores in both in vitro conidial germination and spread plate assays. The efficacy of the synthesised NPs confirmed that these NPs could be used as potential antifungal agents against C. truncatum to control anthracnose in chilli.