Identification of Plant Parasitic Nematodes Associated with Citrus in Dibrugarh District

The present investigation was carried out to determine the occurrence and distribution of plant parasitic nematodes associated with citrus plants of different citrus orchards in Dibrugarh district. A total of 149 soil and root samples were collected randomly from the rhizosphere of citrus plants from the twenty four different citrus orchards of seven blocks from Dibrugarh district. Eight genera of plant parasitic nematodes were found to be associated with citrus plants of Dibrugarh district. Genera of plant parasitic nematodes recorded were namely Tylenchulus, Hoplolaimus, Helicotylenchus, Tylenchorhynchus, Meloidogyne, Xiphinema, Paratylenchus and also nematodes genera found under criconematids. Among them Hoplolaimus sp., Helicotylenchus sp., Tylenchorhynchus sp. and T. semipenetrans were found to be present in most of the samples. Community analysis of plant parasitic nematodes revealed that the genus Hoplolaimus ranked first in relative frequency, absolute frequency, absolute density, relative density and prominence value. Genus Helicotylenchus ranked second in absolute density, relative density and prominence value and genus Tylenchorhynchus ranked third in case of absolute density absolute frequency and prominence value. Results shown that Tylenchulus semipenetrans ranked second in absolute frequency and relative frequency and fourth in prominence value.