Antifungal activity of photo-biosynthesized silver nanoparticles (AgNPs) from organic constituents in orange peel extract against phytopathogenic Macrophomina phaseolina

The soil-borne fungus Macrophomina phaseolina causes charcoal rot, which is one of the most damaging threats to the faba bean in Egypt. The goal of this work was to investigate the inhibitory effects of silver nanoparticles AgNPs on Modiolula phaseolina in vitro, as well as their effectiveness in reducing the incidence of charcoal rot in greenhouse settings. AgNPs were synthesized using a chemical and biological technique in this work. Aqueous trisodium citrate was used to synthesize chemical-AgNPs. However, biological-AgNPs were synthesized using the active chemical components (hesperidin and ascoebic acid are main products) occurred in orange (Citrus sinensis L.) peel extracts. The as-synthesized AgNPs (chemo-ANPs or bio-AgNPs) were full characterized using UV–Vible spectroscopy and transmission electron microscopy (TEM). Bio-AgNPs with spherical forms were found to have an average diameter of 32-47 nm. The antifungal activity of the aqueous extract of orange peel, chemo- and bio-AgNPs at doses of 0, 10, 25, 50, and 100 ppm was tested in vitro against the most virulent isolate of M. phaseolina (isolate number Mp3). It was demonstrated that the orange peel extract showed no antifungal activity. However chemo-AgNPs showed an inhibiting M. phaseolina (Mp3) radial development by 60.5% at a concentration of 100 ppm. In addition, bio-AgNPs were shown to have potential antifungal efficacy, inhibiting the radial growth of M. phaseolina (Mp3) by 100% at a concentration of 100 ppm. In a greenhouse experiment, faba bean seeds treated with bio-AgNPs significantly reduced the incidence of damping-off and charcoal rot diseases and raised the percent of survival plants under greenhouse conditions and soil infested with M. phaseolina. The use of bio-AgNPs improves the growth of faba bean plants growing in greenhouse conditions. As a result, photo-biosynthesized AgNPs from orange peel extract can be employed as a nano-fungicide and nano-fertilizer for faba bean production.