Effect Of Different Multiple Cropping On Soil Nematode Communities In Beijing Greenhouse

This research was chosen for application to an experimental site in Tongzhou (Beijing city,China).Four plots were set up to plant vegetables, The total numbers of root-knot nematodes and the free-living nematodes populations were investigated respectively. In order to understand the infection of different multiple cropping to individual density, nematode communities and biology diversity. The results are as follows:1. Nematodes were identified mainly into seven orders: Rhabditida,Tylenchida, Aphelenchida, Dorylaimida, Chromadorida, Araeolaimida, Enoplida.Furthermore they were distinguished into four trophic groups: bacterivores,fungivores, plant parasites, omnivores/predators,they included one-order plant parasites and six-order nonplant parasites.2. The density of second stage juvenile of root-knot nematodes (J2) on the different multiple cropping showed that: the number of the resistant plot of root-knot nematodes was least, which reached the highest level in Aug. Sep. in the susceptible plot of root-knot nematodes and the tolerant plot of root-knot nematodes,and in Jun.Oct. in the resistant plot of root-knot nematodes.Those indicated the multiple cropping of the resistant plot of root-knot nematodes not only reduced the density of second stage juvenile of root-knot nematodes (J2),but also advanced or declined the fastigium of root-knot nematodes,and the ratio of harmful plant nematodes was less.3. The analysis of influence of different multiple cropping to four trophic groups showed that the multiple cropping of the resistant plot of root-knot nematodes could decrease the individual density of plant parasites,increase the individual density of bacterivores. The analysis of relativity showed that the multiple cropping of the resistant plot of root-knot nematodes alse could change the relativity of trophic groups of soil nematodes.4. The analysis of community diversity of soil nematodes showed that the richness index, diversity index and evenness index would fluctuate by season. The diversity index and evenness index was least .Those indicated the multiple cropping of the resistant plot of root-knot nematodes could increase the diversity index and evenness index,but the richness...