Indoor pot experiment simulating the natural environment conditions along with high efficiency liquid chromatography (HPLC) method and terminal restriction fragment length polymorphism (T-RFLP) techniques was conducted to investigate the effect of chlorpyrifos on bacterial community diversity and structure of cotton rhizosphere soil. Chlorpyrifos doses in the experiment were 5 mg·kg-1 (recommended dose), 10 mg·kg-1, 15 mg·kg-1 and 20 mg·kg-1, with no chlorpyrifos addition as the control treatment. Diversity indices (including Shannon-Weiner index and Simpson index) were used to evaluate bacterial community diversity. Principal component analysis (PCA) was conducted to determine changes in bacterial community structure. Then the MiCA web tool was used for taxonomic interpretation of TRFs. The results suggested that the degradation half-life of chlorpyrifos doses of 5 mg·kg-1, 10 mg·kg-1, 15 mg·kg-1 and 20 mg·kg-1 were 10.04 d, 11.36 d, 11.55 d and 12.16 d, respectively. After 60 days of treatment, chlorpyrifos was almost completely degraded. At the end of the experiment (60 days after treatment), cotton biomass significantly decreased with increase of chlorpyrifos dose. Plant root growth was also significantly inhibited by chlorpyrifos. The soil rhizosphere bacterial community diversity under chlorpyrifos treatments decreased significantly after 10 d and 30 d of treatment compared with that of control. There was no significant difference between the 10 d and 30 d treatments in terms of diversity indexes under all chlorpyrifos treatments. Soil rhizosphere bacterial community diversity of chlorpyrifos application treatments almost recovered to the normal level after 60 days. With the concentration of chlorpyrifos increasing, bacterial community diversity decreased and recovery time became longer. The bacterial community structure was significantly different between chlorpyrifos treatments and the control, respectively, at 10 d, 30 d and 60 d after treatment, even though chlorpyrifos was almost completely degraded at 60 days. The difference between chlorpyrifos treatments and the control was increased at 60 d after treatment, and 20 mg·kg-1 chlorpyrifos treatment had the most significant difference. Also 60 d after treatment, Nitrospina sp. and Cellulophaga sp. were inhibited whereas Bacillus sp. and Streptomyces sp. enhanced by the presence of chlorpyrifos. This showed that rhizosphere soil bacterial community was restructured after treatment with chlorpyrifos. In conclusion, the study presented a comprehensive evaluation of the effects of chlorpyrifos on cotton rhizosphere soils bacterial community diversity and structure. It suggested that recommended or higher doses of chlorpyrifos resulted in cotton rhizosphere soil bacterial community restructuring with a significantly adverse effect on cotton growth and soil bacterial communities, which was need to pay close attention to ecological security of chlorpyrifos using.%通过室内盆栽试验模拟自然环境条件,采用高效液相色谱(HPLC)和末端限制性片段长度多态性(T-RFLP)技术,研究了土壤使用推荐剂量(5 mg·kg-1)及推荐剂量的2倍、3倍和4倍(10 mg·kg-1、15 mg·kg-1、20 mg·kg-1)毒死蜱对棉花根际土壤细菌群落多样性和结构的影响,以不施用毒死蜱的土壤为对照。结果表明,5 mg·kg-1、10 mg·kg-1、15 mg·kg-1和20 mg·kg-1毒死蜱在土壤中的半衰期分别为10.04 d、11.36 d、11.55 d和12.16 d,60 d时基本完全降解。毒死蜱处理60 d后,棉花生物量显著降低；毒死蜱浓度越高,棉花生物量越低。无毒死蜱条件下不同取样时间根际细菌多样性无显著差异,毒死蜱处理组前30 d细菌多样性均显著降低,60 d时毒死蜱处理组细菌多样性恢复到正常水平。研究发现毒死蜱浓度越高对细菌多样性抑制作用越显著,恢复越缓慢。主成分分析结果发现,第10 d、30 d和60 d毒死蜱处理组与对照组细菌群落结构差异显著,其中60 d时20 mg·kg-1毒死蜱处理组差异最显著,即使土壤中毒死蜱完全降解,根际细菌群落结构仍不会恢复到正常水平。60 d时,被毒死蜱抑制的细菌有硝化刺菌属(Nitrospina sp.)和Cellulophaga sp.等,被激活的有芽孢杆菌属(Bacillus sp.)和链霉菌属(Streptomyces sp.)等。可见,毒死蜱的引入,重新构建了土壤细菌群落结构,显著影响棉花生长,对棉花根际土壤微生态环境冲击较大,应对其生态安全性予以重视。
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