ABSTRACT
Green synthesized silica nanoparticles (SiNPs) and their optimization
under different pH values i.e., (5, 7, 9, 11) giving sizes 20, 40.2, 70.2 and
95.5 nm, were evaluated for controlling Harpophora maydis the causal
agent of late wilt disease in Zea maize in vitro and in vivo. Under laboratory
conditions, PDA medium revealed that all tested SiNPs sizes, 20, 40.2, 70.2
and 95.5nm at different concentrations (0.5, 2.5, 5 and 10 ppm) significantly
inhibited the mycelia radial growth of Harpophora maydis. Reduction
increased by increasing concentration compared to control. The most
efficient treatment was SiNP- 20 nm followed by SiNP-40.2 nm.
Greenhouse experiment indicated that seed coated by SiNPs significantly
reduced the infection percentage of late wilt and enhanced the germination
percentage compared with check treatment (70.8%). The SiNP-20 nm
followed by SiNP-40.2 nm introduced superior reduction in disease
incidence (88.2 and 87.7% reduction, respectively) at concentration 10 ppm.
The lowest effect was SiNP-95.5 nm which gave 52.9% reduction. Results
of field trails during 2019-2020 growing season at Giza and Gemmeza
disease nurseries indicated that treated seeds with SiNPs showed significant
reduction in maize infected with late wilt compared with check plants
(78.3% and 81.7% at Giza 2019, Gemmeza 2020, respectively). Also, there
were significant differences between treatments in yield average of the two
seasons. The disease reduction and yield increased with increasing
concentrations. The SiNPs-20 nm and SiNPs-40.2 nm treatments were the
most efficient treatments in decreasing disease incidence and enhancing
yield when recorded 6.7% at 10 ppm at first season (Giza-2019) for both
treatments while gave 6.7% and 8.3% in the second season at Gemmeza-
2020, respectively. On the other hand, average yield were 29 ard/fd in cases
of SiNP-20 nm and 27.3 ard/fd in case of SiNP-40.2 nm. In contrary, the
lowest treatments were the concentration 0.5 ppm of treatments SiNPs 95.5,
70.2 nm. Where, the infection was 34% and average yield of 17.6 ard/fd for
SiNP-95.5 nm and it was 26.3% infection % which yielded 18 (ard/fd) in
treatment SiNP-70.2 nm at Gemmeza location. It could be concluded that
using the green synthesized SiNPs ecologically welcomed at sizes 20 and
Egypt. J. of Appl. Sci., 36 (3) 2021 1-19
40.2 nm, were more efficient than that with higher sizes in controlling maize
late wilt disease and enhancing maize yield productivity.