Root-Knot Density as a New Index Can Quantitatively Diagnose the Damage of Root Nematodes to Plant Growth

Root-knot nematode disease occurs frequently due to continuous monocropping and excessive water nitrogen input. The degree gall index are often used evaluate the damage of root-knot disease. However, weak correlation between these two indicators tobacco leaf dry weight has been reported. objective this study was verify whether use density (RKD)—the number per unit root or volume—as a new indicator could describe growth yield quantitatively. A total 3000 plants from 60 independent plots were classified according symptom leaves in situ. 6 each plot selected sampled represent six levels 360 plants. responding roots taken out with auger. leaves, stems, knots as well volume, degree, determined for all separately. Our results showed that: (1) nematodes had negative while weight, not correlated; (2) length diameter ≥2 mm significantly positively correlated weight; (3) RKD negatively (4) decreased increase average reclassified groups, which index. highlighted that proposed paper can be quantitatively future research practical diagnosis nematodes.