Regulation Effects Of Soil Anaerobic Disinfection(ASD) On Soil Properties And In The Yield And Quality Of Flue-cured Tobacco

Tobacco is one of the economic crops that should avoid growing on the same land continuously.But,continuous cropping has become a common planting phenomenon in the production of tobacco because of the motivation of interest and the limited arable land.Therefore,tobacco continuous cropping would increase the spread of soil-borne diseases and insect pests,and cause the tobacco-planting soil to be hardness,poor permeability and maladjusted nutrient,which would ultimately affect tobacco growth and development and reduce yield and quality of tobacco.Anaerobic soil disinfestation（ASD）is an emerging,non-polluting and effective soil disinfection method.In order to explore an economical,environment-friendly and efficient method for eliminating tobacco continuous cropping obstacles,five kinds of organic materials such as tobacco stem（YG）,rice straw（JG）,rapeseed meal（CP）,rice bran（MK）and bagasse（GZ）were added in this study,and the ASD treatment without the addition of material（CK1）and the native soil（CK）were used as controls.The effects of ASD on soil quality and microbial community structure analyzed with the addition of different organic materials.Field experiments were carried out to research the ASD on the soil properties,soil-borne disease and the yield and quality of tobacoo with the the addition of rice bran（MK）and wood chips（WC）appling in at four levels(12,15,18,21 t·hm^-2),and the ASD treatment with no addition（CK1）was used as control.The results would provide theoretical basis and practical reference for the application and promotion of soil anaerobic disinfection in tobacco production.The main findings are as follows:（1）Soil physical and chemical properties and the activities of soil enzymes were affected by ASD significantly.ASD with the additions of different organic materials increased soil p H value,reduced soil EC and Eh,and improved soil nutrients.The add of tobacco stem（YG）increased the contents of available potassium and organic matter significantly,while rapeseed meal（CP）raised the contents of total nitrogen,organic matter,available nitrogen and the activities of catalase and urease.The field experiment showed that the ASD treatment with wood chips significantly elevated the soil p H,EC,organic matter,catalase and sucrase activities in Debao area,and the effects of high application level were better than those of the low application level.In Jingxi production area,different rules were observed.The addition of rice bran（MK）increased the soil EC,soil nutrient,and the activities of soil catalase and sucrase,butthere was no significant difference in the treatments of different application.（2）The ASD treatments with the additions of different organic materials could reduce the diversity of soil microbial community significantly.The proportions of the bacteria at the phylunm level and the fungi at the class level.were changed obviously by ASD.The components of microorganisms of the ASD added with rapeseed meal and tobacoo stem were notably different from those of CK and CK1.The relative abundance of the Firmicutes were increased sharply,and that of Clostridiaceae,Ruminococcaceae and Bacillaceae families were also increased significantly.While the relative abundance of the pathogenic fungi Xanthomonadaceae was reduced remarkably.Furthermore,the relative abundances of the saprophytic fungus Humicola and Penicillium were increased obviously,but the fungal fungus Fusarium was decreased markedly.In addition,the amounts of R.solanacearum was reduced extremely for the ASD treatment with the addition of CP and YG,which were reduced by 82%and 81%,respectively.（3）Field experiments showed that it was efficient for controlling the soil-borne deseases when applying the ASD method with the addition of MK.The incidence rates and the disease indice of tobacco bacterial wilt,root rot and black shank were decreased distinctively for the treatment of MK-21 in Debao and Jingxi areas.（4）The growth and economic traits of tobacco in Jingxi and Debao were affected significantly by the application of ASD.The plant height,stem circumference,numbers of leaves and leaf area of tobacco were increased obviously,especially for the application of ASD with the add of the rice bran（MK）.The economic traits of flue-cured tobacco were improved significantly by the addition of MK,and the treatments of MK-15 and MK-18showed excellent effects in Debao and Jingxi production areas,respectively.（5）The chemical composition and quality of flue-cured tobacco were influenced by the application of ASD with the addition of different organic materials.The conventional chemical compositions of tobacco leaves,such as the contents of total nitrogen and nicotin,were increased notably by the application of ASD with the add of MK,and the increasing range of which was larger than that of WC.The treatment of MK-21 showed excellent effects in improving the chemical composition of tobacco leaves.Correspondingly,the sensory qualities of flue-cured tobacco,such as fragrance quality,fragrance quantity and physiological strength,were raised significantly by the application of ASD with the addition of MK,but reduced obviously by WC.Furthermore,the treatment of WC showed little effects in the appearance quality of the C3F leaves,while the treatment of MK had an great positive effect on improving the appearance quality of the B2F leaves.Considering the influences of ASD on soil property,flue-cured tobacco quality and yield,it is recommended to apply MK-15 and MK-18 as additive material.In addition,the two materials of tobacco stem and rapeseed meal had significant effects in improving soil quality and inhibiting R.solanacearum,which would provide theoretical basis for the subsequent field implementation.