Role Of Soil Anaerobic Disinfestation In Controlling Bacterial Wilt

Tomato（Solanum lycopersicum）is one of the most important vegetables in the world.It is rich in nutrients and has a reputation as the king of fruits and vegetables,which is also one of the main types of vegetables in Chinese agricultural production.However,due to the monoculture and intensification of commercial tomato planting patterns,continuous cropping obstacles is increasing year by year,and large-scale outbreaks of soil-borne diseases and soil degradation have become increasingly serious.Bacterial wilt is a destructive soilborne disease induced by Ralstonia solanacearum,which severely restricts the growth of tomato.In order to prevent and control bacterial wilt of tomato,different carbon sources（rice bran,wheat bran,peanut cake）were chosen to study the effects of anaerobic soil disinfestation（ASD）on the control of bacterial wilt soil physical,chemical properties and soil enzyme activity.The content of metal ions Fe²⁺,Mn²⁺and organic acids and volatile ammonia in soil influenced by ASD were also determined.The result are as follows:（1）ASD treatments with different carbon sources have significant control effects on disease control.Compared with CK（no treatment）,ASD treatments effectively reduced the incidence of R.solanacearum and enhance growth of tomato plants,ASD with rice bran（ARB）,wheat bran（AWB）and peanut cake（the APB）application showed 100%suppression of the disease.Anaerobic treatment without organic materials（D）resulted in more than 10%of the incidence.Compared with CK,the contents of R.solanacearum in soil were decreased by 91.42%⁹7.14%for different ASD treatments.ASD with peanut cake（APB）significantly increased net photosynthetic rate and stomatal conductance in tomato leaves.（2）ASD treatments significantly influenced soil physicochemical properties and enzyme activity.Compared with CK,ASD treatment could significantly increase soil pH,with an increase of 0.4-1.2,but decrease at 6 days after treatment.ASD with wheat bran（AWB）and peanut bran（APB）significantly increased soil electrical conductivity.All ASD treatments significantly reduced soil Eh,which was decreased to negative values at 4 d after treatment and remained in a reduced state until the end of anaerobic treatment.ASD significantly increased soil urease and dehydrogenase activity,decreased soil acid phosphatase activity,but no significant effect on soil nitrate reductase activity.（3）ASD treatments also have obvious effects on the content of metal ions,organic acids,and volatile ammonia in the soil.ASD treatments significantly increased water-soluble ions in soil,releasing a large number of low-valent metal ions such as Fe²⁺,Mn²⁺and Cl^-.Compared with the control,a large amount of Fe²⁺and Mn²⁺were detected in soil treated with ASD,which were increased with the increase of treatment time,especially for the treatment with peanut bran（APB）,the content of Fe²⁺in soil was increased from 100 mg·kg^-1 to 2500 mg·kg^-1,and Mn²⁺from 10 mg·kg^-1 to 320mg·kg^-1,Furthermore,NO₃^-,PO₄^3-,and SO₄^2-content in soil were significantly reduced after ASD treatments.Application of wheat bran（AWB）and peanut bran（APB）significantly increased soil organic acids such as malic acid,citric acid,and succinic acid during the processing.During the ASD treatment,the release of volatile ammonia from the soil was significantly higher than that of the control,and the addition of peanut bran（APB）increased the most,Antibacterial experiments showed that Fe²⁺,Mn²⁺,and citric acid,succinic acid,and volatile ammonia all had a direct supressing role on R.solanacearum.