Microbiology and Biotechnology Research: An Overview Vol. 7

Green gram (Vigna radiata) is frequently affected by fungal diseases such as anthracnose caused by Colletotrichum lindemuthianum, southern blight caused by Sclerotium rolfsii, powdery mildew, and cercospora leaf spot, which can hinder germination, kill plants, or significantly reduce yield. This study investigates the antifungal activity of green-synthesised zinc nanoparticles (ZnNPs) against C. lindemuthianum and S. rolfsii using the poisoned food technique. ZnNPs were synthesised using plant extracts of mehandi (Lawsonia inermis), neem (Azadirachta indica), marigold (Tagetes erecta), and ginger (Zingiber officinale), following compatibility assessment with the test pathogens. Different concentrations (100, 250, and 500 ppm) of ZnNPs were evaluated alongside corresponding plant extracts and zinc nitrate hexahydrate (250 ppm).

Results indicated significant fungistatic activity, with Mehandi ZnNps at 500ppm exhibiting the highest efficacy, demonstrating minimal mycelial growth (28.00mm) and a growth inhibition rate of 68.88%, followed by Marigold and Neem ZnNps against Colletotrichum. As for Sclerotium, Neem ZnNps at 500 ppm exhibited the highest efficacy, demonstrating minimal mycelial growth (15.00 mm) and a growth inhibition rate of 83.33%, followed by ginger and Mehandi. All tested ZnNps concentrations outperformed their respective plant extracts and Zinc nitrate hexahydrate, confirming the potential of green-synthesised ZnNp as effective agents. These findings highlight the potential of green-synthesised ZnNps as eco-friendly and effective antifungal agents, offering a sustainable alternative to chemical fungicides for managing fungal diseases in green gram. Further studies are recommended to investigate the mechanisms of antifungal action, field-level efficacy, and environmental impact, including effects on soil health and non-target organisms.