Abstract: It is necessary to evaluate the ecological risks of transgenic Bt rice on soil non-target organisms before the rice is released to the market. In 2010, a field trial was conducted to investigate the effects of planting three genetically modified rice lines HH1, T2A-1, and T1C-19 that expressed Bacillus thuringiensis toxin (Bt) on the soil microbial characteristics and the abundance, trophic groups, and ecological indices of soil nematode. After rice harvest following one year planting, genetically modified rice line HH1 increased the soil microbial biomass carbon (MBC) significantly, as compared to the nontransgenic rice parent line MH63. In contrast, the three transgenic Bt lines had minor effects on the soil microbial biomass nitrogen (MBN), but T2A-1 and T1C-19 had great effects than HH1. As compared with the parent line, the three transgenic Bt lines had no significant effects on the nematode abundance, tropic group composition, and plant parasite index (PPI). Significant differences were observed in the structure index between Bt rice (T2A-1 and HH1) and nonBt rice (MH63). Our study suggested that transgenic Bt rice could have significant effects on the structure and function of soil ecosystem in a short period. Longer term monitoring in combining with the determination of Bt toxin content in soil would help to the comprehensive evaluation of the ecological risks of transgenic Bt rice on soil non-target biotic communities.

Key words: village scale, landscape pattern change, low-slope hilly area, GeoEye-1, WorldView-3, Northwestern Yunnan Province.