Abstract: Soil microbial organisms are an important components of farmland ecosystems, and soil microbial community structure and activity reflects quality of the soil to some extent. A pot experiment was conducted to investigate effects of application of river sediment on population and functional diversity of soil microbe and Cd content of winter wheat grain under four different sediment application levels, 0 (control), 20, 60 and 100 g•kg^-1. Results show that spike quality and 1 000-grain weight of wheat were much higher (P < 0.05) in Treatments 60 and 100 g•kg^-1 than in control and no significant difference was found in grain Cd content between the four river sediment application rates. Compared with control, application of river sediment had no significant influence on populations of bacteria, fungi and actinomyce, and no significant influence on average well color development (I_AWCD), Shannon index (H'), Simpson index (D) and McIntosh index (U) of microbe at 96 h, either. Principal component analysis (PCA) demonstrated that only by PC3 which explains 14.22% of the total variable variance, can the differences between control and the treatments be distinquished in carbon utilization of soil microbial community, while PC1, PC2 and PC4 which explains 21.76%, 16.32% and 11.62%, respectively, of the total variable variance are useless in this aspect. All of the above imply that in this study river sediment application rate has no significant effects on Cd content of winter wheat grain, functional diversity of soil microbe and soil quality.

Key words: river sediment application, soil microbe, function diversity, winter wheat grain, Cd, Biolog analysis