| Continuous crop monoculture is a common mode of production,particularly in protected cultivation.Crop growth obstacles which caused by continuous monoculture are a well known significant agricultural problem,but the differences of continuous monoculture with different crops,as well as the complexity of the effects of other environmental and soil tillage on crop growth barriers,increase the difficulty of the study on continuous monoculture obstacle.Therefore,the study on the rule of soil ecological deterioration in special crop continuous monoculture,special environment and tillage system has important significance for solving special crop continuous monoculture obstacle.This text,using 1-13 stubbles tomato continuous monoculture soil samples as material,analyze the factors of soil ecological deterioration of protected tomato continuous monoculture,based on the analysis of protected tomato growth rule under different monoculture stubbles.The purpose of our research is to provide theoretical support for regulating protected soil continuous cropping obstacle.The main results are as follows:1.It was clear that tomato plant height,stem diameter,plant fresh and dry weight,root activity,yield and quality were all increased from 1st to 3rd stubbles under protected continuous monoculture.The above indexes were not significant difference at 3-9 stubbles,but were all decreased significantly at the 11th and 13th stubbles.Comparing with 3-9 stubbles,MDA content at the 11th and 13th stubbles were significantly increased and tomato plot yield at 11 and 13 stubbles were decreased respectively about 19.09%and 20.58%on average.The results indicated that tomato plant showed significant physiological barrier phenomenon at continuous monoculture 11th and 13th stubbles.2.It was clear that soil water content,EC value,nutrition element content and organic matter content were all increased from 1st to 3rd stubbles under protected continuous monoculture and had no significant difference at 3-9 stubbles generally.Comparing with 3-9 stubbles,soil total P content was increased significantly and soil available N,available P,available K,available Fe,available Mn,available Cu and organic matter content decreased significantly at the 11th and 13th stubbles.Soil EC at the 11th and 13th stubbles showed a significant rising and was respectively increased about 43.92 and 39.10%on average comparing with 3-7 stubbles.Soil pH at 13th stubble was showed significant difference and was decreased about 0.25 units on average comparing with 3-9 stubbles.Correlation analysis indicated that soil available K,available Fe,available Mn,available Cu were all significantly positively related with tomato yield.As a whole,the physicochemical property of soil was deteriorated and soil nutrition content was unbalance at the 13th stubble.3.It was clear that soil enzyme activity,soil microbial abundance and soil microbial functional diversity were all increased from 1st to 3rd stubbles under protected continuous monoculture and had no significant difference at 3-11 stubbles.Soil total microbial abundance,bacterial abundance,ratio of bacterial and fungal abundances,soil the average well color development（AWCD）,microbial community functional diversity indexes,carbon source utilizing AWCD value and the activities of urease,invertase,neutral phosphatase at the 13th stubble were all decreased significantly,but the fungi abundance was increased significantly.Correlation analysis indicated that soil the average well color development（AWCD）and the activities of urease,invertase were all significantly positively related with tomato yield.The results indicated that enzyme activity,microbial abundance and microbial functional diversity in soil at 13th stubbles was deteriorated significantly and continuous monculture obstacle appeared.4.It was clear that soil bacterial community genetic diversity at the 13th stubble had a significant change.Comparing with the 1st stubble,two genus including Gp2 and Gp5 in Acidobacteria were significantly decreased at 3-11 stubbles and these had no significant difference at genus level at 3-11 stubbles.The number of different OTU at 13th stubble was obvious rising.Using PCA,PCoA and Beta diversity analysis methods,the 13th stubble significantly separated with all the other stubbles.LEfSe analysis manifested that:seven genus including Gp4、Gp6、Gp7、Gp10、Gp17、Gp18、Gp19 in Acidobacteria,Latescibacteriageneraincertaesedis and WPS2generaincertaesedis at the 13th stubble were all significantly increasing.5.It was clear that soil fungi community genetic diversity at the 11th and 13th stubbles had significant change.Abundance of pathogenic bacteria Alternaria at the 13th stubbles had significant increased.OTU cluster analysis at genus level of soil fungi among different stubbles indicated that the 11th and 13th soil fungi genus level OTU were clustered in one group,all other stubbles were clustered in another group.LEfSe analysis manifested that comparing with 1-9 stubbles,different species abundance of soil fungi at the 11th and 13th stubbles were significantly increasing.Abundance of cDothideomycetes,oPleosporales,oMicroascales,fMicroascaceae and three fungi species which were undefined or unidentified significantly increased at the 11th stubble.Abundance of cTremellomycetes,oCystofilobasidiales,fCystofilobasidiaceae,oMortierellales,fMortierellaceae,fPleosporaceae,fLasiosphaeriaceae and five fungi species which were undefined or unidentified significantly increased at the 13th stubble.In conclusion,protected tomato appeared significant continuous monoculture obstacle at the 11th and 13th stubbles and tomato yield is significantly decreased.The dominating reason of protected tomato continuous monoculture obstacle was the deterioration of soil environment factors,and soil continuous monoculture obstacle had relationship with soil pH,EC value,available nutrition content,organic matter content,the activity of urease,invertase,neutral phosphatase,bacteria abundance,fungi abundance and microbial diversity. |
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