The effectiveness of three chemical inducers resistance, hydrogen
peroxide (H202) at 0.25, 0.5 and 1%, Bion (benzo 1,2,3)thiodiazole-7-
carbothioic- methlye ester) and salicylic acid at 2, 4 and 8 mM were tested in
greenhouse under artificial inoculations. all tested inducers significantly
reduced damping-off, wilt and root rot incidence, Salicylic acid at 4 mM and
Bion at 8 Mm followed by Hydrogen peroxide at 0.25 % gave the highest effect
on all parameters of disease incidence and consequently increasing
percentage of healthy survival plants. Increasing concentration of salicylic acid
up to 4 mM and hydrogen peroxide up to 0.25 % led to a decrease in their
effect on reducing the disease incidence. While the effect of Bion on reducing
of diseases incidence increased with increasing of their concentration. This
study indicated that, there is a correlation between induced resistance and
some biochemical changes in roots tissues like increased the activity of
oxidative enzymes (peroxidase and polyphenoloxidase) and accumulation of
phenol compounds. Salicylic acid at 4 mM followed by Hydrogen peroxidase at
0.25% and Bion at 8 mM recorded the highest content of phenol compounds
and highest increase of activity of oxidative enzymes (peroxidase and
polyphenoloxidase) in roots of peanut plants.