Interaction of Root-knot Nematode (meloidogyne Javanica) and Tomato as Affected by Hydrogen Peroxide

The effect of hydrogen peroxide (H2O2) on root-knot nematode (RKN, Meloidogyne javanica) in tomato was investigated. Soil drenching with exogenous H2O2 was done using seven H2O2 concentrations (1, 10, 100, 250, 500, 750 and 1 000 mM) at different application times (24 hours before the time of plant inoculation with the RKN (T1), at the time of inoculation (T2), and 24 hours after the inoculation time (T3). The nematode reproduction rate (eggs/g fresh root) was significantly reduced in all H2O2 treatments compared with the untreated control. The lowest reduction in nematode reproduction occurred at 10 mM H2O2. The application times T1 and T2 were significantly higher in reducing the reproduction rate than T3 at 250, 750 and 1 000 mM H2O2. The content of endogenous H2O2 in the treated plants was significantly higher than in the non-treated plants. Some phytotoxicity was apparent at the higher concentrations of H2O2 (≥ 500 mM) in the treated plants due to the accumulation of the endogenous H2O2. The treatments with 1 and 10 mM H2O2 did not differ from the untreated control in plant chlorophyll content while the content was significantly reduced at the higher concentrations. Exogenous application of H2O2 may have a direct effect on the nematode reproduction and an indirect effect on the treated tomato plants that can be elicited by H2O2 to resist the nematode infection.