Study the Effect of Three Species of Medicinal Plants of the Mint Family on Pathogenicity and Damage Root Knot Nematode Meloidogyne javanica in Tomato

Introduction: Root-knot nematodes (Meloidogyne spp.) are important plant pathogens that make large damage to the crops. The activity of root-knot nematode and reaction of host plant results in the development of several knots on the root, which interrupts water and food absorption system of the plant. Among popular methods for controlling root-knot nematodes are physical methods (soil solarization and flooding), farming methods (crop rotation, weed removal, contaminated roots removal, fertilization, soil reinforcement, planting time adjustment, and use of resistant varieties), and chemical methods (disinfection with pesticide and foliar spray. Incomplete control, high cost and environmental problems (chemical compounds) have directed some researchers toward to use non-chemical methods such as herbs and herbal products for the management nematodes. Mankind has used medicinal plants throughout the history in both direct and indirect ways. Today, medicinal plants have a considerable share of medical products. The nematicidal effect of many plants has been demonstrated and the use of plant products has been considered as a safe method to control root-knot nematode. This method is cheap and easy to use, does not cause environmental pollution, and is able to improve the soil in structural and nutritional terms. Organic plants possess a wide range of secondary metabolites such as phenyls, flavonoids, coinons, tanons, essences, alkaloids, saponins, and sterols. These substances are biodegradable owing to their natural origin and do not pollute the environment. Today, active plant compounds are given much attention because they are less durable and do not have the negative impact on mammals and non-target organisms. Plant products including essences and extracts are usually used to control plant diseases nematodes. Therefore, due to the favorable impact of plants in controlling Root-knot nematodes, In this study, the presence of several herbs (thyme, hyssop, and savory) are pathogenic nematode damage in tomato was examined. Materials and Methods: In this study, the effect of the medicinal plants of the mint family on root knot nematode, three herb thyme (Thymus vulgaris), savory (Sature jahortensis) and hyssop (Hyssopus officinalis) was used. In order to prepare the inoculum required for the test, root-knot nematode- contaminated tomato samples were collected from the farms or greenhouses of Chaharmahal Bakhtiari Province (one of the provinces of Iran). To separate and extract eggs and larvae, contaminated roots were chopped into 1-2 cm pieces by the method of Hussey & Jonsen were mixed in 10% hypochlorite sodium solution in a mixer for one minute. Then the mixture was put in the 400-mesh sieve under water current so as to remove hypochlorite sodium. Finally, the eggs were collected in distilled water. Furthermore, to prepare sufficient larvae, nematode egg masses were transferred to petri dishes and kept in the incubator for 24 hours until the eggs hatched. Finally, the obtained eggs and larvae were used to carry out the test. A greenhouse experiment was as factorial in a completely randomized design with single culture tomato and mixed with herbal hyssop (Hyssopus officinalis), thyme (Thymus vulgaris), and savory (Sature sp), in the presence and absence of nematodes. Results and Discussion: The tomato growth parameters (dry weight of root, stem, leaf, root length, shoot length) and nematode pathogenicity (Number of galls, egg massesin1/g of root of ,the number of eggs in each egg masses, second instar larvae per 100 gr of soil and reproductive factors) were evaluated three months after nematode inoculations. Data were analyzed using SAS statistical software comparing MSTATC software and LSD test was performed. Statistical analysis of data showed the significance difference between treatments. ANOVA results demonstrated that the use of three species of medicinal plants of the mint family is a significant effect on the pathogenicity of nematodes. For example One of them main indicators of pathogenic nematode are galls on the roots. The savory (Sature jahortensis), gall formation by nematode was reduced. In other words among the plants under study, Savory (Sature jahortensis) was the most effectiveness in reducing damage and pathogenicity of nematode, and thyme and hyssop were in next grades respectively. This inhibition may be due to a direct effect on larvae and egg root secretion or indirectly by providing suitable conditions for growing tomato and defense against nematode attacks. Conclusion: Collectively, the tested medicinal plants in this study, had good control effect against root knot nematode and can be used in nematode management programs. And their application in Natural conditions also is investigated