In this research, the effects of antagonist bacterium (Bacillus cereus) and salicylic acid (SA) as chemical inducer alone and in combination against root knot nematode (Meloidogyne javanica) as the most important nematode in Iran, on cucumber roots (cv. superdominus) was investigated. The used concentrations were 109 cfu/ml for bacteria and 5 mM for SA. In greenhouse experiments some parameters were evaluated including nematode and plant growth criteria in treated plants with the two above materials. Results of this experiment showed that combination of biocontrol agent and chemical inducer decreased galling, egg masses and egg numbers on roots of cucumber. In biochemical analysis, also, some of defense compounds such as hydrogen peroxide and peroxidase activities were measured. Results showed that hydrogen peroxide level and peroxidase activity increased after inoculation until 4th and 5th days respectively and then decreased gradually. Soil drenching of B. cereus and SA caused maximum induction in roots.
Key words: Bacillus cereus, salicylic acid, Meloidogyne javanica, peroxidase, hydrogen peroxide.
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