Study Of Chlorine Dioxide On Control Of Apple Replant Disease

In this experiment,Malus hupehensis Rehd.seedlings and young apple trees were used as materials in pot and field to study the effects of chlorine dioxide treatment of apple replanted soil on plant growth and soil microbial community structure.The main results are as follows:1.The 600 mg·L^-1chlorine dioxide treatment increased the biomass of potted Malus hupehensis Rehd.seedlings,and the change was significant compared with the replanted control.In August 2022,plant height,ground diameter,fresh weight and dry weight of 600mg·L^-1chlorine dioxide increased by 27.20%,15.95%,100.70%and 76.28%,respectively.2.The replanted soil treated with chlorine dioxide promoted the root growth of Malus hupehensis Rehd.seedlings.The root length,root surface area,root volume and root tip number of Malus hupehensis Rehd.seedlings were increased by 31.74%,96.54%,257.29%and 85.29%,respectively,when treated with 600 mg·L^-1chlorine dioxide in apple replantation soil.In addition,the activities of SOD,CAT and POD were increased in chlorine dioxide treatment,while the content of MDA was significantly decreased compared with that in replanted soil.3.Pot experiment showed that chlorine dioxide treatment reduced the total amount of microorganisms in replanted soil.In July 2022,the number of bacteria,fungi and actinomyces in the soil treated with 600 mg·L^-1chlorine dioxide decreased by 37.77%,56.11%and49.98%,respectively.In August,the number of bacteria,fungi and actinomyces in soil treated with 600 mg·L^-1chlorine dioxide decreased by 31.50%,34.25%and 36.22%,respectively.Moreover,the activities of urease,sucrase,neutral phosphatase and catalase decreased significantly in July and August after treatment.4.Chlorine dioxide significantly reduced the content of phenolic acids in replanted soil.After 600 mg·L^-1chlorine dioxide treatment,the contents of vanillic acid,syringic acid,vanillin,ferulic acid,benzoic acid,coumarin,phloretin and phlorizin in soil were 0.94 times,0.73 times,0.90 times,0.57 times,0.31 times,0.85 times,0.40 times and 0.50 times of the replanted control,respectively.5.Chlorine dioxide treatment changed the microbial community structure of replanted soil.Laboratory tests showed that chlorine dioxide solution inhibited the mycelium growth and conidium germination of Fusarium oxysporum,Fusarium proliferatum,Fusarium moniliforme,Fusarium solani.The effect of 600 mg·L^-1chlorine dioxide on the four Fusarium species was more significant.Chlorine dioxide treatment changed the fungal community structure of the replanted soil,and the relative abundance of the harmful bacterium Fusarium in 600 mg·L^-1chlorine dioxide treatment soil decreased by 50.65%compared with the replanted soil control.6.Field experiment results showed that chlorine dioxide treatment of apple replanted soil can significantly promote the growth of replanted young apple trees.In Qixia test site,compared with replanted soil control,plant height,ground diameter and shoot growth increased by 25.68%,10.70%and 77.00%respectively under 600 mg·L^-1chlorine dioxide treatment,while the number of soil bacteria and fungi decreased by 45.32%and 31.75%,respectively.In Penglai test site,plant height,ground diameter and shoot growth increased by24.63%,23.13%and 78.23%,respectively,while the number of bacteria and fungi decreased by 36.29%and 34.28%,respectively.