Background

Onions, a vital agricultural crop rich in carbohydrates and essential minerals, face severe threats from Fusarium oxysporum, the causative agent of basal rot disease. This study assessed the effectiveness of extracellular, green-synthesized silver nanoparticles (AgNPs), produced by Aspergillus terreus AUMC 15760, in managing basal rot disease caused by F. oxysporum AUMC 15798.

Results

AgNPs ranging from 12.1 to 28.7 nm were incorporated into PDA media at concentrations of 50, 100, 150, and 200 ppm, achieving fungal growth inhibition rates of 24.88%, 40.77%, 54.44%, and 69.33%, respectively. A greenhouse experiment was carried out using onion seedlings, with a randomized complete block design (RCBD) to compare eight different treatments: 100 ppm AgNPs (spray), 50 ppm AgNPs (spray), 100 ppm AgNPs (soil application), 50 ppm AgNPs (soil application), Dovex spray (50%), Dovex soil application (50%), a negative control, and a positive control. Greenhouse results showed a significant reduction in disease severity, with Dovex lowering it to 20%. AgNPs at 50 ppm reduced severity to 57.77% (soil) and 35.55% (spray), while 100 ppm further decreased it to 31.1% (soil) and 22.2% (spray). The application of 100 ppm AgNPs improved plant growth parameters. It also enhanced chlorophyll a, chlorophyll b, and carotenoid levels. The greatest reductions in phenolic (0.34 mg/g) and anthocyanin contents (0.48 mg/g), as well as peroxidase (0.44 µmol/min) and catalase activities (0.19 µmol/min), were recorded in plants treated with 100 ppm AgNPs (spray).

Conclusions

AgNPs effectively control basal rot disease, boost plant growth, and regulate antioxidant activity.

How to cite: Hegazy MG, Gad M, Lamlom SF, et al. Improved resistance to basal rot disease and promotion of onion plant growth by Aspergillus terreus-mediated silver nanoparticles. Electron J Biotechnol 2025;77. https://doi.org/10.1016/j.ejbt.2025.05.003.