Evaluation of biological control of Fusarium oxysporum f. sp. radicis-cucumerinum using different isolates of Trichoderma harzianum antagonist and activation of defense mechanisms of cucumber plant

Root and stem rot of cucumber with Fusarium oxysporum f. sp. radicis-cucumerinum is one of the most harmful diseases in cucumber greenhouses in Iran. Chemical fungicides do not have the acceptable ability to control this pathogen. Also, due to their economic costs and adverse effects on the environment, the use of biocontrol agents in the control plant diseases has been considered in recent years. Trichoderma antagonist isolates has been shown to be an effective biocontrol agent against a wide range of fungal pathogens. In this study, the effect of Trichoderma isolates on root rot and cucumber rot fungi was investigated. Three Trichoderma isolates were obtained from the mycology collection of the Department of Plant Protection, University of Tehran. Mean peroxidase activity (POX) as a marker of induced resistance was measured using a spectrophotometer. Also, the effect of Trichoderma isolates on disease control in greenhouse conditions was determined by soaking the soil with spore suspension of antagonist and fungal pathogen. All three Trichoderma isolates T11, T6 and T9 have an acceptable effect on growth inhibition of F. oxysporum f. sp. radicis-cucumerinum. T11 and T9 isolates showed 85.51% and 81.03% inhibition of mycelial growth of F42 strain, respectively. Peroxidase activity was assessed within seven days after inoculation. The highest peroxidase activity was observed on the fourth day in T11 isolate. Based on the results obtained in this study, it can be concluded that T11 isolate (T. harizianum T11) had the greatest effect among Trichoderma isolates in inducing resistance.