The present study was conducted to evaluate 28 commercial cultivars and two promising breeding lines of barley in terms of resistance to Meloidogyne javanica nematode and to investigate the synthesis level of peroxidase, superoxide dismutase, catalase and polyphenol oxidase enzymes in different days after inoculation in greenhouse condition. Based on the results of evaluation, Jolge and Nimrouz cultivars were highly resistant, Rihan and Zarjow were very susceptible. The rest of the cultivars were ranked between these groups in resistant, moderately resistant and moderately susceptible groups. Comparison of the activity of antioxidant enzymes in highly resistance cultivars (Jolge and Nimrouz) and very susceptible cultivars (Rihan and Zarjow) roots showed that the activity of peroxidase, superoxide dismutase and polyphenol oxidase increased in the root of the highly resistant cultivars and decreased or remains unchanged in very susceptible cultivars. Nevertheless, catalase showed a decreasing trend after inoculation by nematodes in highly resistance cultivars, and in general; its level in resistant cultivars was less than susceptible cultivars. Therefore, changes in the activity of these enzymes can be attributed to different levels of resistance among these cultivars

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