The nematode populations of wheat fields in Xiaoquan village,Qingshui county,Tianshui city,Gansu province of China were investigated
preliminarily.The relationship of nematode populations and their quantities was presented.The recorded
nematodes were divided into five trophic groups:Phytophage nematode,Bacterivorous nematode,Insect nematode,Fungivorous nematode and Omnivore/Predator nematode.The results showed that the observed nematodes in the wheat fields in Tianshui region belong to 11Genus in 9 Families of 4 Orders,among which beneficial(non plant feeding) nematodes were related to 2 orders,6 families and 6 genus and harmful(plant parasitic) nematodes were related to 2 orders,3 families and 5 genus.The phytophage nematodes were absolutely dominant,accounted for 67.7% of total nematodes,bacterivorous nematodes for 27.4%,insect nematodes for 4.15% and omnivore/ predator nematodes for 1%.Fungivorous nematodes were not been found in this study.
Wasilewska index was only 0.401 which was much lower than 1.000,a general index of soil health.The index data indicated the health problem of soil,caused by wheat replanting year after year on the same fields.The results of this study could contribute to be basic data for Tianshui crop planning and adjusting.