Control Effect Of Soil Disinfection On The Yam "Paste" Disease And Effects On Soil Environment

The planting area of Dioscorea Oppositifolia in Hebei Province is more than 11 333hm~2,mainly distributed in Baoding city.However,due to years of planting,soil-borne diseases have occurred seriously,and the disease incidence of serious block is as high as 90%.One of the main diseases of the D.oppositifolia continuous cropping obstacles is the yam"paste"disease.The occurrence of yam"paste"disease has greatly reduced the D.oppositifolia commodity rate,resulting in reduced yield of D.oppositifolia.The block with lighter disease is reduced by 40%-50%,and the block with serous disease has no yield.The yam"paste"disease has become a difficult problem that restricts the development of Hebei D.oppositifolia industrialization.In this study,the control effect test of soil disinfection treatment against yam"paste"disease was carried out,and the effect of soil disinfection treatment on soil environment were also studied.The results are as follows:1.Yam"paste"disease caused changes in yam tissues:from the comparison of the tissue sections of normal D.oppositifolia and the D.oppositifolia with"paste"disease,the cork layer cells of the D.oppositifolia with"paste"disease was shrunk,the color becames darker,the cell destruction was serious and the arrangement was irregular,and the cells corked.Cell died,and no cell nucleus.The structure of starch granules and needle crystals in the column structure is unclear.2,Chloropicrin fumigate soil can prevent yam"paste"disease:the effect of chloropicrin fumigation on the control yam"paste"disease is better than that metham sodium disinfection on yam"paste"disease.And the control effect of chloropicrin fumigation on yam"paste"disease is between 84.61%-97.56%,the total output increased by 55.72%-71.47%,among which the yield of commercial yam increased by 165.00%-561.00%;The control effect of metham sodium disinfect soil on yam"paste"disease was 8.93%-19.37%,and the total output increased by 4.94%-7.32%,the yield increase of commercial yam is 43.60%-63.60%.3.Soil disinfection can alleviated the soil acidification、the soil mineral elements deficiency disease and the soil microbial community structure imbalance caused by continuous cropping D.oppositifolia.The effect on soil pH:the pH value of the soil leaching solution was measured by the pH meter.The results showed that the soil pH values were 7.60 and 7.32 after fumigation treatment in the depth of 0-20 cm soil layer and the depth of 20-40 cm soil layer.The pH values of the untreated soil was 6.04 and 6.15,the soil acidification was improved after fumigation.The effect on soil metal ion contents:the copper ion,zinc ion,magnesium ion and calcium ion in four soil layers of each sampling point were determined by ICP-MS.The result showed that after fumigation,the copper ion content of the soil in the depth of 0-20cm was 16.15mg/kg,which was significantly higher than the content of the untreated soil,the content of copper ion was 14.67mg/kg.The copper ion content in the soil layer at 20-80 cm depth was not significant.After fumigation treatment,the zinc ion content of soil layer at20-40 cm depth was significantly higher than that of untreated soil by 117.94 mg/kg.There was no significant difference in calcium ions and magnesium ion between the soil before and after fumigation treatment.The effects on soil microbial community structure:the results of high-throughput sequencing were used to determine the fungal and bacterial contents in the soil before and after treatment.The results showed that the bacterial diversity of CK0-20 cm soil layer was higher than that of fumigation 0-20 cm,the fungal content of CK0-20 cm and CK20-40 cm soil layer was significantly higher than the fungal content of fumigation 0-20 cm and fumigation 20-40 cm soil layer.Three pathogens were isolated from severely diseases soils,namely:F.oxysporum,F.solani and F.chlamydosporu,these three pathogens were not found in the soil after chloropicrin fumigate,indicating that chloropicrin fumigation can improved the microbial community structure in the soil.