Monitoring Bt Protein Residues In Soil And Its Effects On The Communities Of Soil Biology

This paper based on three cotton fields in yancheng city,jiangsu province,identical soil type which has always planted transgenic resistant-pest cotton for two years,six years and ten years.According to citton's different vegetal period, we gathered the cotton field surface layer soil (0-20cm).The number of microorganisms and partial of physiological function groups,the diversity of bacteria and minitype invertebrates communities in soil were studied. Meanwhile, we also studied the quantity of Bt protein residues and its degradation dynamic in soil.The main results of this study are as follows:1.The number of culturable bacteria,fungi,denitrifying bacteria and Nitrobacteria changed significant with the different sampling period.With the period of transgenic resistant-pest cotton plant increase,the number of bacteria,fungi,denitrifying bacteria and Nitrobacteria are no notable change.However, the number of aerobic azotobacter is different due to different planting years.2.The diversity of soil bacteria in cotton fields showed a downward trend with the transgenic cotton plant consecutive years of increases.Dominant species are identical in three cotton fields , but the proportion between the two dominant species in soil samples was also gradually increased.3.Soil invertebrates community constitutes are similitude in three cotton field,and the total number of invertebrates has consistent regularity with the sampling period.There is no significant different in number of predominance groups in three cotton field,but the Simpson index, Shannon-wiener diversity index and Evenness are ascend with the increase of plant period,the richness debase with the increase of plant period.4.The quantity of Bt insecticidal protein residues is very low in three cotton field soil.We detected that pure Bt insecticidal protein degradated rapidly in soil. The degradation speed was slowdown gradually along with the study progressed.