Division of Nematology, Indian Agricultural Rsearch Institute, New Delhi-110 012.
Seventeen different Meloidogyne incognita populations collected from 13 different states were evaluated for their reaction on differetial host-plants, Cotton cv. Delta pine-16, Tobacco cv. NC-95 and Tomato cv. Rutgers. All the populations multiplied on susceptible tomato cv. Rutgers. However, in case of cotton even though penetration and gall formation occurred with all the populations, egg-mass production was recorded only with 7 populations while in tobacco, the penetration of J2 occurred with 8 populations, gall and egg-mass production was observed only with 4 populations. The reproductive factor both in cotton and tobacco was generally low when compared with tomato. Based on the reaction of test populations on host differential plants, four races were identified. Race-l was found to be widely prevalent.
Root-knot nematode, Meloidogyne incognita, races, reproductive factor
