ANTIBACTERIAL EFFECT OF ESSENTIAL OIL OF MEDICINAL HERBS AND THEIR INHIBITORY EFFECTS ON RALSTONIA SOLANACEARU BACTERIA (POTATO SOFT ROT FACTOR) AND PECTOBACTERIUM CAROTOVORUM BACTERIA (POTATO WILTING FACTOR)

Potato is one of the plants that annually suffer from damages due to the soft rot and tuber disease in the cellar. Nowadays, utilizing from herbal essential oils for acquisition of natural antibacterial agents has been of great interest to control plant-pathogens. In present study, five medicinal herbs of Thymus sativum L, Coriandrum sativum L., Cuminum cyminum L., Rosmarinus officinalis L. and Eucalyptus globules L. were extracted using distillation with water and their inhibitory effects on Ralstonia solanacearu bacteria (potato soft rot factor) and Pectobacterium carotovorum bacteria (potato wilting factor) examined through disc diffusion method1. Tube dilution method2 was used to determine the minimum inhibitory concentration and minimum bactericidal concentration. The variance analysis was carried out on tests in the form of a completely randomized factorial design. Comparison of means was performed based on Duncan's multi-domain test (MSTAT-C software). Thymus sativum L. essential oil was used in greenhouse stage, because it showed the highest level of inhibitory effect on both bacteria in the laboratory stage. The obtained results showed that Thymus sativum L. essential oil had the most antibacterial activity and effect compare with other essential by creating an inhibitory shaft diameter of 34,8 mm. For greenhouse experiments, Thymus sativum L. essential oil was used with a concentration of 0,5% by spray method and a concentration of 1% by pouring essential oil into the soil. According to the results, Thymus sativum L. reduced the occurrence of potatoes' soft rot disease up to 41% and potatoes' bacterial wilt up to 44%. Therefore, Thymus sativum L. essential oil can be utilized as an inhibitor to manage these two diseases in potato plant due to its appropriate antibacterial function.