Green synthesis of silver nanoparticles using Artemisia persica extract and evaluation of their activity on onion gray rot fungus

Gray rot is a severe onion disease caused by the Botrytis fungus. Currently, green synthesis of silver nanoparticles (Ag NPs) using plants is being explored as an alternative to chemical poisons. In this research, pathogenic fungi were isolated and identified from onions with rotting symptoms. The biosynthesis of Ag NPs was performed using the aqueous extract of Artemisia leaves. The synthesis of Ag NPs was characterized using various techniques such as UV–Vis, FTIR, and TEM. The biosynthesis of Ag NPs was confirmed by observing the color change from light yellow to brown after 15 min at room temperature and dark conditions. The UV spectra revealed that the surface plasmon resonance is at 420 nm. According to TEM analysis, the average size of Ag NPs was approximately 20 nm. The synthesized Ag NPs were then tested against Botrytis fungus. Ten Botrytis strains were isolated, and the S3 isolate from the Islamabad region was selected. In vitro conditions showed that the growth inhibition rate of Ag NPs and Carbendazim poison, alone and in combination, against Botrytis fungus were 53.84%, 100%, and 100%, respectively. Moreover, Ag NPs and Carbendazim poison, alone and in combination, showed 100% shelf life of onions in storage within 3 and 2 months, respectively. Therefore, the synthesized Ag NPs were found to be effective in controlling pathogenic fungi without using fungicides.