Effects Of Cover Crops Of Wheat And Common Vetch On Growth And Soil Ecological Environment Of Continuous Cropping Chinese Cabbage

As a kind of green fertilizer,cover crop play a positive role in improving soil environment.Previous studies have shown that cover can increase soil available nutrient content,improve soil p H,and reduce soil EC value.Moreover,cover can increase soil microbial total,reduce the abundance of harmful microorganisms in soil,and promote crop growth.The effects of cover crops of wheat and common vetch on cabbage growth and soil microorganisms are not well understood.In this study,the continuous cropping soil of Chinese cabbage of Baicheng Team 3,Acheng District,Harbin for over 10 years was selected as the research object.With non-covered crops as the control,cover crop of wheat(W),cover crop of common vetch(P)and cover crops of wheat and common mixed vetch(WP)were set as three cover treatments.The effects of cover crops of wheat and common vetch on the growth and soil ecological environment of continuous cropping Chinese cabbage were investigated by using q PCR and Illumina Mi Seq high throughput sequencing technology.The purpose of this study was to screen OTU the cover crop treatments that promote the growth of Chinese cabbage seedlings,and clarify the microbial mechanism of their growth promotion and soil microorganisms,so as to provide theoretical basis and technical support for cover crops of wheat and common vetch to reduce the continuous cropping obstacles of cruciferous Chinese cabbage.The main results as follow:1.Cover crops of wheat and common vetch significantly promoted the growth of Chinese cabbage,and two consecutive cover results also showed that cover crops of wheat and common vetch mixed had a better growth promoting effect on Chinese cabbage.2.Cover crops of wheat and common vetch increased the contents of soil organic carbon,organic matter and total carbon,while cover crops of wheat and common vetch mixed significantly reduced soil p H.3.Cover treatment increased the abundance of fungi,but had little effect on the abundance of bacteria.P and WP decreased the abundance of Bacillus and Pseudomonas.4.Bacterial diversity was decreased by cover treatment,but the cover treatment increased the relative abundance of Sphingomonas,Bacillus,Massilia,TM7 a and Bryobacter.In addition,OTU1471(Bacillus)and OTU2453(Sphingomonas)were increased in the cover treatment compared with the control.5.Wheat treatment with cover and mixed treatment with cover significantly decreased the relative abundance of Olpidium,common vetch treatment with cover and mixed treatment with cover significantly decreased the relative abundance of Fusarium,and mixed treatment with cover significantly increased the relative abundance of Chaetomium.In addition,OTU1471(Bacillus)and OTU2453(Sphingomonas)and fungi OTU5(Mortierella),OTU12(Fusarium),OTU3(Gibberella)and OTU8(Botryotr)were increased in all the cover treatments compared with the control.The relative abundance of OTU7(Plectosphaerella),OTU14(Nectriaceae),OTU19(Humicola),Fungi OTU6(Humicola),OTU4(Pyronemataceae),OTU9(Preussia),OTU10(Fusarium),OTU13(Lophotrichus),OTU16(Mortierella),OTU30(Acaulium)and OTU28(Sodiomyces)were decreased.6.The results of PCo A analysis of bacteria showed that PCo A2 of control and each cover treatment was significantly separated at 30 days,and the bacterial colony structure was different.The results of PCo A analysis of fungi showed that there were significant differences in PCo A1 between control and each cover treatment,and there were significant differences in fungal community structure between control and each treatment.7.Mantel test results showed that soil organic matter,organic carbon and EC value were the main environmental factors affecting soil bacterial community structure,while soil EC value and p H value were the main environmental factors affecting soil fungal community structure.In conclusion,the cover crops of wheat and common vetch increased the beneficial bacteria in the soil,promoted the growth of cabbage plants,and played a positive role in alleviating the growth problem of continuous cropping.