Abstract: The research results about the effect of root-knot nematodes disease on tobacco yield and quality character indicated that when the tobacco plants were damaged by root-knot nematodes, the protein content of the tobacco leaves increased, but the contents of nicotine and reducing sugar decreased. The relationship between initial density and relative yield, initial density and disease intensity, disease intensity and yield loss were studied, and these mathematics models were established.

Key words: Tbacco, Root-knot nematode, Root-knot index, Yield loss rates