Abstract
Nowadays there is an urgent need for using the natural resistance elicitors due to the numerous problems caused by the chemical ones and these natural elicitors can be used in organic agriculture. This study examines the ability of onion dry scale extract to enhance the resistance in eggplant against bacterial wilt. This evaluation was performed through studying the change in polyamines and antioxidant metabolism in two groups of eggplant seedling (the first treated with prepared onion dry scale extract and the other non-treated) are infected with Ralstonia solanacearum. The onion dry scales extract enhanced the polyamines content. In treated infected (TI) plants the polyamine oxidase (PAO) activity significantly increased only on the 7th day after infection. On the 14th day after infection, the PAO activity and H2O2 significantly decreased. In the TI group, the activity of the antioxidant enzymes significantly increased in the two stages, consequently, the lipid peroxidation decreased in the TI group, which appeared in decreasing the activity of lipoxygenase activity at the 14th day after infection and decreasing the content of malonyl dialdehyde. Moreover, exogenous application of onion dry scales extract completely suppressed the percentage of dead plants due to wilt disease 14 days after sowing in non-sprayed plants in comparison with the sprayed plants being 84.37%. The study confirmed that onion dry scales extract spray can be considered as an organic method for fighting bacterial wilt in eggplant through the improvement of polyamine metabolism and the antioxidant machinery.