Abstract
Background
Fusarium oxysporum causes wilt disease, which is considered a destructive disease, leading to decreased growth and death of most infected plants.
Materials and methods
After 7 days of incubation of Streptomyces clavuligerus on starch nitrate medium, the synthesis of silver nanoparticles (AgNPs) was done by using the supernatant from the microorganism. The color changed to dark brown, proving the formation of AgNPs. The size of AgNPs was analyzed using transmission electron microscope. Various concentrations of AgNPs (20, 40, 60, 80, and 100 mu l) were investigated against F.?oxysporum by using agar well diffusion method. Disease symptoms, disease index percent, phytochemicals, and metabolic indicators of resistance in plant, such as the reaction to induction of systemic resistance, were recorded in tomato plants.
Results and conclusion
The resultant AgNPs had size from 4 to 38 nm and were oval to spherical in shape. The observed inhibition zones were 12, 18, 19, 23, and 27 mm in diameter correspondingly. The growth of Fusarium has been reduced by 60, 40 ppm, and followed by 20 ppm. Treatment with different concentration of nanoparticles resulted in different responses regarding the total phenol content, proline content, and total protein of Fusarium-infected plants. Applications of 60 ppm by foliar shoot+root immersion and root immersion methods were the best treatments and reduced percent disease indexes by 8 and 11%, respectively. Therefore, it could be suggested that the application of tested treatments could be commercially used for controlling Fusarium wilt disease of vegetable plants, as they are effective against this disease, are less expensive, and are safe.