Abstract
Metal oxide nanoparticles have recently garnered interest as potentially valuable substances for the management of plant diseases. Copper oxide nanoparticles (Cu
2
ONPs) were chemically fabricated to control root rot disease in cucumbers. A scanning electron microscope (SEM), X-ray diffraction (XRD) and photoluminescence (PL) were employed to characterize the produced nanoparticles. Moreover, the direct antifungal activity of Cu
2
ONPs against
Fusarium solani
under laboratory, greenhouse, and field conditions were also evaluated. In addition, the induction of host-plant resistance by Cu
2
ONPs was confirmed by the results of enzyme activities (catalase, peroxidase, and polyphenoloxidase) and gene expression (
PR-1
and
LOX-1).
Finally, the effect of Cu
2
ONPs on the growth and productivity characteristics of the treated cucumber plants was investigated. The average particle size from all the peaks was found to be around 25.54 and 25.83 nm for 0.30 and 0.35 Cu
2
O, respectively. Under laboratory conditions, the study found that Cu
2
ONPs had a greater inhibitory effect on the growth of
Fusarium solani
than the untreated control. Cu
2
ONP treatment considerably reduced the disease incidence of the root rot pathogen in cucumber plants in both greenhouse and field environments. Defense enzyme activity and defense genes (
PR1
and
LOX1
) transcription levels were higher in cucumber plants treated with Cu
2
ONPs and fungicide than in the untreated control. SEM analysis revealed irregularities, changes, twisting, and plasmolysis in the mycelia, as well as spore shrinking and collapsing in
F. solani
treated with Cu
2
ONPs, compared to the untreated control. The anatomical analysis revealed that cucumber plants treated with Cu
2
ONPs had thicker cell walls, root cortex, and mesophyll tissue (MT) than untreated plants. Cucumber growth and yield characteristics were greatly improved after treatment with Cu
2
ONPs and fungicide. To the best of our knowledge, employing Cu
2
ONPs to treat cucumber rot root disease is a novel strategy that has not yet been reported.