Analysis Of Soil Microbial Diversity In Continuous Cropping Cucumber Under Different Fertilization Conditions

With the development of facility agriculture, Continuous cropping obstacles are becoming increasingly prominent. As one of the main varieties of cucumber vegetable facilities, its mechanism of obstacles and preventive measures by scholars to wider attention. Previous studies showed that soil microbial flora imbalance is one of the main reasons for cucumber continuous cropping obstacles, and that the application of organic fertilizers and microbial fertilizer can effectively relieve cropping obstacles by improve soil physical and chemical properties, and adjust soil microbial ecology. Moreover, inappropriate and excessive fertilization is also leading to the deterioration of soil physical and chemical properties and soil microbial flora imbalance. Therefore, reasonable application of fertilizers organic fertilizer and microbial fertilizer, and to establish a reasonable fertilization strategy has a great significance for sustainable development of cucumber cultivation industry. By setting different fertilization treatments,including chemical fertilizers (FT), common organic fertilizer and chemical fertilizer (FC), bio-organic fertilizer and chemical fertilizer (FB) and no fertilizer (CK). Studying dynamic changes of the Microbial flora and Diversity of Continuous Cropping Cucumber under different fertilizer treatments. Anglicising of abundance of v6/v7 region of 16S rRNA, hcnAB gene, phzF gene and OPZ gene, and understanding of different fertilization on soil continuous cropping cucumber influenced on fungal community structure by means of Illumina MiSeq sequencing technology. In order to maintain soil microbial flora in health under continuous cropping and prevention and mitigation continuous cropping obstacles to provide a theoretical basis.1. Using dilution plate count and PCR-DGGE, to study dynamic change of Microflora and Diversity of Continuous Cropping Cucumber under different base fertilizer treatments. The results showed: With the increasing number of continuous cropping. There is a growing tendency for the microbial number. Compared with CK, FT treatment significantly increased the number of actinomycetes and fungi, and have an obvious inhibitory effect on the number of bacteria. FC and FB treatment produces a favourable effect on the number of bacteria and actinomycetes in varying degree. FC treatment has an obvious inhibitory effect on the number of fungi. FB treatment have an obvious inhibitory effect on the number of fungi in the early of continuous cropping (5 stubble), but promotes increasing number of fungi in later of continuous cropping.Cropping and fertilizer produced different degrees of impact on bacteria and fungi community structure. With the increasing number of continuous cropping,diversity and richness of the bacterium under CK treatment showed an increasing trend, while other fertilization showed a downward trend, and compared with FT and FC, FB treatment produced an obvious effect on maintaining diversity and abundance of bacteria. Cropping have contributed to rising diversity and abundance of fungi under different fertilizer treatment, but the range is smaller than CK.Showing FB>FC>FT abOTU diversity and richness of fungal after continuous cropping 7 stubble.2. Using RT-PCR and PCR-DGGE to study the abundance and diversity of pseudomonas under different fertilizer treatments. The results showed that:compared with CK, the application of fertilizer have a significant role in promoting to increase the abundance of pseudomonas when the first crop, when the eight crop, FT have a significant role in decreasing the abundance of pseudomonas, but there is no obvious change under organic fertilizer. Compared with the first crop, the abundance and relative abundance of pseudomonas were significantly decreased under different fertilizer treatment after continuous cropping 8 stubble. The diversity and richness of pseudomonas community structure have increased under Continuous cropping. The structure of fungi under different fertilizer treatments has large difference in the first crop. However, degree of difference decreased obviously after in the eighth crop. Besides, the ability of maintaining on diversity and richness of pseudomonas in the process of Cucumber Cropping, showed FB> FT> FC. Nucleotide sequence alignment of DGGE bands shows that the abundance of beneficial bacteria, including Pseudomonas fluorescens、Pseudomonas putida, Pseudomonas stutzeri and Pseudomonas sp,increased under fertilization treatments; FB treatment promote increasing the abundance of beneficial bacteria,while the abundance of Pseudomonas alcaligenes declined under FC treatment. The abundance of pseudomonas abOTU antagonistic soil-borne diseases of cucumber increased under continuous cropping, bio-organic fertilizer application can promote increasing the abundance of beneficial bacteria.3. Using RT-PCR to analyze change of the abundance of Fusarium oxysporum (MAT) F. oxysporum f. sp. Cucumerinum (OPZ), the function of hcnAB and phzF on soil of cucumber continuous cropping under different fertilizer. The results showed:Cropping lead to the relative abundance of genes related with soil-borne disease increased and the relative abundance of function gene abOTU may inhibit soil-borne pathogens decreased, this trend is more obvious under fertilizer and bio-organic fertilizer, Common organic fertilizer have a inhibit or mitigation role in the relative abundance of genes related with soil-borne disease increased and the relative abundance of function gene abOTU may inhibit soil-borne pathogens decreased.In addition, In addition, presenting positive correlation between the relative abundance of genes related with soil-borne disease and the relative abundance of function gene abOTU may inhibit soil-borne pathogens.4. IST1 zone of fungi on cucumber cropping (8 stubble) soil under CK、FT、FC、FB and FCB treatments samples processed high-throughput sequencing by Illumina Miseq platform, received 2,696,679 pieces effective sequence, and 2,036,675 pieces of high-quality sequence. Alpha diversity analysis showed that:compared with CK, FC and FT treatment on bulk soil can play a role in promoting increasing the richness of fungi; FT、FB、FC and FCB treatments reduces the diversity and richness of fungi on rhizosphere soil in the degree; consistent with analysis of PCR-DGGE in the 7 crop.Compared with the relative abundance of the main phylumunder different fertilizer treatments showed:compared with CK treatment, the relative abundance of Ascomycota、 Glomeromycota and Zygomycota generally decreased under FT、FC、 FB and FCB treatment, and organic fertilizer application is more significant on relative abundance, the relative abundance of Basidiomycota in rhizosphere soil increased under all treatment,but in the bulk soil,except FB treatment, the relative abundance of Basidiomycota significantly decreased. In addition to FCB treatment, other treatments generally increased the relative abundance of Chytridiomycota, and chemical fertilizer the most significant among all treatment.The most abundant in the soil before 20 kinds OTUs statistical results show that:the abundance of Fusarium solani, Fusarium oxysporum, Acremonium sp and Mortierella alpina are the highest, and the abundance of Fusarium solani, Ascomycota sp, Fusarium oxysporum and Acremonium sp. Are the highest at 20 ahead of the richest OTUs in rhizosphere soil. relative abundance of soil-borne fungal pathogens and beneficial bacteria of crop growth among the 20 ahead of the richest OTUs significant analysis under fertilizer treatments, the results showed: Compared with CK and FT treatment, organic fertilizer can control with the abundance of different soil-borne pathogenic fungi in different degrees in bulk and rhizosphere soil, meanwhile, the abundance of beneficial fungi have different degrees of decline under different fertilizer treatment.Beta diversity analysis showed: regardless of rhizosphere soil and bulk soil, variation in community structure is smaller between FT and CK, and compared with CK, organic fertilizer significantly changed the community of fungi, and community structure have a great degree of differentiation between FB and FC. Principal component analysis (PCA) and cluster analysis classified under the genus level obtained similar results.RDA analysis showed:the community of fungal has a significant differentiation under different fertilization treatment, and the more closely related to physicochemical characteristics. pH is more closely related to the formation of community structure under CK and FT treatment, and TN、PH、RAP、RAK、DOC、TP and AI have the effect of the formation of community structure under FC、FB and FCB treatment.