Green synthesis of silver nanoparticles using guava leaves: an effective strategy to control chilli fruit rot disease

Anthracnose, caused by Colletotrichum capsici, is a significant fungal disease affecting chilli crops, leading to yield losses of 10-25%. Traditional control methods, primarily chemical fungicides, not only pose risks to the environment and soil health but also threaten public safety. In contrast, nanotechnology presents a promising eco-friendly alternative, leveraging the unique properties of nanoparticles, such as their small size and high surface-to-volume ratio, to effectively manage fungal infections with minimal environmental impact.

This study investigates the synthesis, characterization, and antifungal activity of silver nanoparticles (Ag-NPs) synthesized from guava leaf extract against chilli fruit rot. UV-Vis spectroscopy confirmed the synthesis of Ag-NPs with a peak absorption at 431 nm. X-ray diffraction (XRD) analysis revealed a crystalline structure with an average particle size of 42.5 nm, while scanning electron microscopy (SEM) showed spherical nanoparticles with sizes ranging from 30.5 nm to 50.3 nm across different samples. Fourier transform infrared spectroscopy (FTIR) identified functional groups involved in silver ion reduction. Zeta size analysis confirmed particle sizes of 500.1 nm, 1.0 nm, 62.4 nm, 262.8 nm, and 178.8 nm for samples S1 through S5, respectively. In antifungal assays, S1 at 50 ppm exhibited the highest mycelial growth inhibition (47.9%), with significant protective (87%) and curative (93%) effects. Additionally, in in-vitro leaflet assays, S1 demonstrated 86% inhibition of C. capsici at 50 ppm, highlighting its potential as an effective agent for managing chilli fruit rot.

This study presents a rapid, eco-friendly method for synthesizing Ag-NPs using guava leaf extract, showing their potential in managing chilli fruit rot caused by C. capsici. The results highlight their effectiveness in both protective and curative applications, offering a sustainable alternative to chemical fungicides. Future research should focus on scaling up the synthesis process for industrial applications, exploring the long-term environmental impact, and assessing the broader applicability of Ag-NPs in managing other phytopathogenic diseases across various crops. Silver nanoparticles (Ag-NPs) synthesized from guava leaf extract effectively inhibit Colletotrichum capsici, with 86% antifungal activity at 50 ppm. This study highlights an eco-friendly, rapid synthesis method for Ag-NPs as a promising alternative to chemical fungicides in managing chilli fruit rot disease.

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