| Root-knot nematode (Meloidogyne spp.) is a destructive pest of vegetable that reduces production in infested areas and is difficult to manage, especially in greenhouse of continuous planting tomato. For determining the influence of continuous tomato-cropping on root-knot nematode second-stage juveniles (RKN J2), soil nematodes and soil microorganism from rhizosphere soil, the dynamic distribution of J2, free-living nematode and soil microorganism with depth in greenhouse soil of different ages from Taian suburb were investigated from August 2007 to June 2008. Meanwhile, a pot experiment was conducted and the effects of three different nematicides on the soil microorganism and the second-stage juveniles of Meloidogyne spp were studied.The results of the pot experiment showed responses of the second-stage juveniles of Meloidogyne spp(J2) were sensitive to three nematoicides tested, the number of J2 was lower in Rugby (RU) treatment during 0-84 d after nematicide application. Soil microorganism showed different response in nematicide treatment. During 0~84 d after nematicide application, the number of actinomycetes in different treatment showed the similar trend. Fungi and bacteria indicate different response on 3 nematicide.Abamectin and Rugby stimulate multiplication of fungi in 21 d and 42 d respectively. However, the phenomenon of increase disappeared later. Aldicab inhibited significantly the multiplication of soil fungi(P<0.05), and simulated the multiplication of bacteria. It was found that Rugby simulated the multiplication of bacteria within 21 d after application and then inhibited, and no effects on soil fungi diversity.The results of the experiments in greenhouse soil showed the individuals of J2 increased with the planting years, the number of J2 in three soil layer of 0-year and 5year was significantly less than that of other tested soil (P<0.05), the average mean of J2 in 0-year and 5-year were 1.1 and 2.1·100 g-1 dry soil. In 8-year, 10-year and 12-year soil, the number of J2 were 154.9, 68.3 and 861.8·100 g-1 dry soil respectively, and the number of J2 increased with soil depth, the J2 individual mainly distribute in 20 to 30 cm soil layer. The number of free-living nematode also increased with the increasing of soil depth, regulator was not be found between continuous cropping time and soil free living nematode. The percentage of individual of J2 in total soil nematode were lower in 0-year and 5-year, the population of J2 was rare groups, keep a dynamic balance with the population of soil free living nematode. However, J2 of root knot nematode population in 8-year, 10-year and12-year were dominant groups, and ratio of individual of free-living nematodes and root-knot nematodes J2 were lower significantly than that of 0-year and 5-year (P<0.05). Therefore, the ratio of free living nematode and RKN J2 could be considered as early warning of RKN disease, and measure the severity of the disease.Fourteen families and 24 genera were observed,mainly in Protorhabditis, Diploseapter, Meloidogyninae, Helicotylenchus, with 74.4% of the soil nematode community.Plant parasitic nematodes and bacterivorous were more abundant trophic groups present in greenhouse soil of different ages. Populations of the both trophic groups increased with the increasing of planting-year in greenhouses.There was a significant difference in the vertical distribution of soil nematodes in greenhouse soil of different ages, the numbers of nematodes of 10 years greenhouse soil were significantly higher than other years in both 0-10 cm and 10-20 cm soil layer, while the numbers of nematodes of 5 years greenhouse soil were highest in 20-30 cm soil layer.The community diversity index such as Shannon-wiener's index, Simpson index, Pielou's evenness index and Species richness decreased with continuous cropping, the community diversity index of 0 year greenhouse was significantly higher than other years.Maturity index (MI), plant parasite index(PPI) and PPI/MI were effective in distinguishing differences in nematode community structure in different ages of greenhouses.The functional group index indicated that continuous cropping altered the ratio of r- and k- choice of plant parasite nematodes.In different continuous planting years soil, the number of bacteria was the highest, followed by actinomycete, fungi is the lowest. Microorganisms and microbial biomass carbon of different continuous planting soil all decreased with the depth of soil, 0-10 cm﹥10-20 cm﹥20-30 cm. With the increas of continuous croppinge time, the total numbers of soil microorganisms and biomass C increased, however, some peak appeared in different continuous planting time plots, the amount of soil bacteria, fungi, actinomycetes and biomass C were up to the maximum value in continuous planting 5, 8, 10 and 8 years. The distribution of soil microorganisms in different soil depths showed the similar trend, however, soil microbial biomass carbon was different changes in different continuous planting time soil during the whole experiment.
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