Screening And Compound Agents Developed Based On Vermicompost Flora Bacteria Antagonistic Soil-borne Diseases

With the increasing of planted area and cultiving time, continuous cropping obstacles of crop is becoming serious problem and limiting the development of argricultural industry. Vermicompost, which was generated from organic waste by earthworm, have been commercialized as a substrate and fertilizer. It promoted physical and chemical of continuous cropping soil, regulated soil flora. Multiple functions were relevanted beneficial microbe of vermicomposts. To research microbial community diversity and screen beneficial microbe of vermicomposts, it was good for applying vermicompost. But effects of microbial community diversity of vermicomposts on different feedstocks and directly applied beneficial microbe were few studies. First, this paper studied effects of vermicomposts microbial community diversity of different feedstocks and changed feedstock. Then strains, which were isolated from vermicompost and garden soil, againsted to pathogenic fungi and had plant growth promoting activities in vitro, and identified by characteristics of morphological and molecular biology methods. This paper tested the compatibility of strains, strains growth of different pH values. Composite microbial agents, which were selected from mixed culture of different mediums, had treated soils of continuous cropping cucumber with different fertilizers. The effects of microbial community diversity of composite microbial agents treated soils of continuous cropping cucumber by plate count methods and PCR-DGGE. There results supported biological control methods and theoretical basis to solve continuous cropping obstacles of cucumber. Results were summarized as follows:(1) The earthworms were fed with different feedstocks, such as cattle manure, pig manure and sludge. Then the bacterial community diversity between feedstock and vermicompost were determined by DGGE analysis of PCR-amplified bacterial16S rDNA V3region. The results showed that:the diversities of bacterial community in various vermicomposts were all decreased as compared with different feedstocks. The similarity coefficients of the bacterial community between vermicompost and feedstock were different among all the tested samples, which were from15.3%to37.7%; feeding with different kind of feedstocks resulted in the different similarity coefficient of bacterial community among all the types of vermicomposts, but some vermicompost samples showed similar bacterial community diversity. The highest similarity value was found between two vermicomposts derived from cattle manure and pig manure, respectively, both of which were about one fold higher than their corresponding feedstocks; the bacterial community diversity of fresh vermicomposts declined and tended to be stable with the extension of feeding time after changing the feedstock from pig manure to cattle manure. The bacterial community diversity in feedstock could be changed after feeding by earthworm. The similarity coefficient between cattle manure and its corresponding vermicomposts was decreased from33.2%on0d to14.8%on21d, and then tended to be stable after21d.(2)8bacteria and4actinomycetes were isolated from vermicomposts and garden soils, exhibited strong activity against to Fusarisum oxysporumf, Rhizoctonia solaniKuhn, Cochliobolus sativu and Fusarium oxysporiumf, and had variable plant growth promoting activities in vitro.12strains were identified by characteristics of morphological and16S rRNA blast showed that,8strains were most similarly Bacillus,4strains were most similarly Streptomyces.(3)8bacteria and4actinomycetes were grown in mixed culture by compatibility test. They were grown of pH=6～8mediums and in acidic were grown better than in alkaline. In mixed cultures, they were initially identified optimized medium to culture composite microbial agents, in order to improve the activities of antagonism and growth-promoting.(4) Compared to different treatments of composite microbial agents and fertlizers, the results showed that, composite bacterial and actinomycete agent were varying degrees of promoting the bacterial and actinomycete counts, but reduced the fungal counts by different fertlizers treatments; they were also varying degrees of promoting the ratio between bacterial, actinomycete and fungal. With no fertilizer and fertilizer+organic fertilizer treatment, composite bacterial agent obviously promoted the rhizosphere bacteria. composite actinomycete agent obviously promoted the rhizosphere bacteria with fertilizer and fertilizer+organic fertilizer treatment. composite bacterial agent and composite actinomycete agent were varying degrees of proportion of rhizosphere microbial and regulation of bacterial community structure with different fertlizers treatments.