Inducing resistance reaction of orange against blue mold Pencillium italicum using the essential oil of Francoeuria undulata (L.) Lack

Mold decay is one of the most important diseases after harvesting citrus fruits, produced by Pencillium italicum fungi. It annually causes high amount of losses in citrus products. The essential oil of coca bush, Francoeuria undulata (L.) Lack, has high antibacterial properties on microorganisms. Therefore, in two separate experiments, the effect of various concentrations of essential oils (four levels including 0, 400, 800 and 1600) on inducing resistance of orange's fruit was evaluated against blue mold (two levels: without pathogen and with pathogen) via studying the defense enzymes. The present study was conducted as factorial based on completely randomized design with three replications. In second experiment, the effect of essential oil on pathogen control was studied at concentrations of 0, 400, 800, and 1600 in a completely randomized design. Results of analysis of variance showed that the interaction of concentration×pathogen at 48 and 96- hour time periods was significant on three enzymes including catalase, peroxidase and phenol. Also, the results of analysis of variance showed that the effect of coca bush essential oil concentration on inhibitory of pathogen growth on fruit was significant. The interaction of pathogen× plant type showed that the highest content of phenol, peroxidase and catalase was associated with control treatments, while high phenol content was observed in pathogenic treatments with coca bush. The interaction of presence and absence of pathogen×concentration showed that the highest phenol content was obserevd in control treatments at 0 and 800 ppm concentrations. Peroxidase content was high in healthy treatments, while there was no difference among various treatments in terms of catalase content. The interaction of plant type×essential oil concentration showed that there was no significant difference among various treatments in terms of phenol, peroxidase and catalase content.