Relationship between the Occurrence of Tobacco Root-knot Nematode and Soil Physiochemical Properties in Enshi Tobacco-growing Area

In order to explore the relationship between the occurrence of tobacco root-knot nematode and soil physiochemical properties, 25 typical healthy and 25 typical diseased rhizosphere soil samples collected from Xuan'en Conunty, the typical tobacco root-knot nematode region in Enshi City of Hubei Province, were detected for organic matter, mean weight diameter of aggregates, water content, bulk density, capillary moisture, pH, alkali-hydrolyzale nitrogen, available phosphorus, rapid available potassium, changeable Ca²⁺, Mg²⁺ and Na⁺, available Fe, Mn, Cu, Zn and B. The most critical soil factors of tobacco root-knot nematode were identified by the t-test, correlation analysis and principal component analysis were used to systematically analyze the differences in the above 17 indicators between healthy and diseased soils. The results showed that the content of MWD, water content, capillary moisture capacity, exchangeable Ca²⁺, available Fe, Mn, Cu, Zn and B increased significantly by 54.76%, 6.45%, 7.61%, 64.90%, 37.25%, 50.62%, 56.67%, 60.14% and 33.33%, respectively (p<0.01), but the bulk density reduced significantly by 4.00% (p<0.01). The results also showed that the cumulative contribution rate was 68.62% from the above 10 indicators with significant differences, and the soil nutrient supply and water condition is the two principal component. According to the results, the available Mn and the capillary moisture capacity was established as the minimum data which could affect the occurrence of root-knot nematode disease.