| [Object] Due to long-term continuous cropping,film mulching cultivation,and straw returning,cotton verticillium wilt is becoming more serious,which reduced the yield and quality of cotton in Xinjiang province.It is urgent to carry out biocontrol of cotton verticillium wilt for agricultural ecological balance and sustainable development.The purpose of this study is to determine the effects of different biological agents and application dosages on cotton verticillium wilt and soil micro-ecology under drip irrigation conditions.[Methods] A field experiment was conduced in 2016.Six biological agents were set in this experiment,and each agent contained three application dosages.The methods of fied investigation,biostatistics,soil ecology,and molecular biology techniques were used to clearly the effects of biological agents on cotton verticillium wilt and soil microbial population abundance.[Results](1)The comprehensive benefits of six agents was in the order of T3>T5>T1>T4>T2>T6.The proper application dosage of T3 biological agent treatment was at 1.5-2 kg/667m2.Biological agents T1,T2,T4,and T5 application dosage were 3 kg/667m2,1.2 kg/667m2,45 kg/667m2,and 4 kg/667m2,respectively.(2)Soil pH did not have a significant change but the soil organic matter increased by different degree after six biological agents application.Soil organic matter content was increased with the increasing of formulation rate in each agent treatment basically.This study had found that the formulation rate in which soil organic matter content was higher corresponded to the ground part of cotton growth was better.(3)Soil urease activity was significantly increased and phosphatase and catalase activity had no significant change after six biological agents dripping into soil.In T3 and T5 treatments,soil urease activity was increased significantly with the formulation rate increased and the increasing effect was very obvious.(4)Soil verticillium dahliae was significantly reduced after biological agents dripping into soil.By comparing to control,the verticillium dahliae abundance was the least in T3 treatment,the second was T5,followed by the T4,T1,T2,T6.Soil verticillium dahilae was decreased significantly with the application concentration increased except T2 treatment.The verticillium dahliae abundance of agent application at 1.2kg/667m2 level was significantly lower than the other two application levels in T2 treatment.(5)Soil bacteria was increased by times after biological agents application and the number of soil bacteria was increased with the formulation rate increased in each agent.Compared with the control,the number of soil actinomycetes was increased in different degrees from T1 to T5 except T6 treatment,which was no significant between different formulation rates.The number of soil fungi was decreased significantly in all treatments,which was decreased with formulation rate increased in T1,T3,T4 and T5 treatments and increased with formulation rate increased in T2 treatment.(6)Soil microbial diversity was changed obvious after biological agents application.The gemmatimonadetes and proteobacteria were increased significantly but the acid bacillus and verrucomicrobia were decreased significantly of bacteria.The ascomycete was increased significantly but basidiomycetes and imperfect-fungi were reduced of fungus.The actinomycetes abundance was increased significantly.[Conclusion] Six biological agents application at proper dosage have some control effect against cotton verticillium wilt and reduce the abundance of pathogen verticillium dahliae In addition,biological agents application can also promote soil enzyme activity and microbial community abundance.However,the further study need to carry out because of the application effects of biological agent varied with climatic,soil,and crop in different regions. |
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