Community analysis of plant-parasitic nematodes in yamuna khadar region of Delhi

An exploratory survey of the vegetable belt of Yamuna Khadar region of Delhi was conducted to assess the nematode community structure. Soil and root samples, representing 20 locations, were examined. Five important genera of plant-parasitic nematodes, namely, Meloidogyne incognita, Tylenchorhynchus vulgaris, Hoplolaimus indicus, Helicotylenchus indicus and Heterodera cajani were widespread. M. Incognita was present in 12 fields surveyed where brinjal (Solanum melongena L.), tomato (Lycopersicon esculentum L.), chilli (Capsicum frutescens L.) and poi (Basella rubra L.) were being cultivated. The relative density and prominence value of M. incognita was 63.6 and 628.9 reapectively. Heavy root-knot galling on brinjal roots was observed at 3 locations where the population density of second-stage juveniles (52) was 1698,5573 and 3525 per 200 cm³ soil. In a tomato field, the number of juveniles of M. incognita was as high as 5440 per 200 cm³ soil. The relative densities of T. vulgaris, Helicotylenchus indicus and Hoplolaimus indicus were 13.5, 13.4 and 5.4 and prominence values were 139.5, 101.2 and 59.7, respectively. The juveniles of Heterodera cajani were found at only two locations giving relative density of 3.9 and prominence value of 25.5 Most of the vegetable crops grown in this area showed yellowing of foliage, stunting and patchy growth.