Effects Of Hydrogen Peroxide On The Soil Environment Of Apple Replant Disease And The Growth Of Malus Hupehensis Rehd. Seedlings

At present,due to the limitation of land resources,regional development and cultivation conditions,most of the old orchards in my country have frequently encountered obstacles in the reconstruction process,which greatly hinders the sustainable development of my country’s apple industry.Therefore,in this study,different concentrations of hydrogen peroxide were used to treat continuous cropping soil for pot experiments.By studying the effects of different treatments on the growth of Malus hupehensis Rehd.seedlings in the continuous cropping soil microbial environment,it provided an effective theoretical basis and technical support for alleviating the obstacles to continuous cropping of apples.The experiment was carried out from October 2020 to March 2022 at the School of Horticultural Science and Engineering,Shandong Agricultural University,the National Apple Engineering Technology Center,and the State Key Laboratory of Crop Biology.A total of 5 treatments were set up in the experiment:old apple orchard soil（CK1）,methyl bromide fumigation（CK2）,1.5%concentration hydrogen peroxide treatment（H1）,3%concentration hydrogen peroxide treatment（H2）,and 4.5%concentration hydrogen peroxide treatment（H3）.The main findings are as follows:1.Different concentrations of hydrogen peroxide treatment can promote the growth of Malus hupehensis Rehd.seedlings and increase the biomass.Compared with the old apple orchard soil,different treatments promoted the increase of biomass of Malus hupehensis Rehd.seedlings to different degrees,among them,the treatment with 4.5%hydrogen peroxide（H3）had the best effect,and its plant height increased by 63.1%,ground diameter increased by126.6%,fresh weight increased by 846.1%,and dry weight increased by 969.6%.2.Different concentrations of hydrogen peroxide treatment reduced the number of microorganisms in the soil and optimized the structure of soil microbial community.Each treatment reduced the number of microorganisms in the soil to varying degrees compared to the old apple orchard soil,among them,the application of 4.5%hydrogen peroxide（H3）treatment reduced the most,and the number of bacteria decreased by 91.0%,and the number of fungal decreased by 87.6%,and the number of Fusarium oxysporum decreased by 90.8%.3.Different concentrations of hydrogen peroxide treatment reduced the activity of soil enzymes.Compared with the old apple orchard soil,the application of 4.5%hydrogen peroxide treatment（H3）has the largest reduction,and its phosphatase decreased by 36.5%,sucrase decreased by 24.9%,and urease decreased by 44.4%.4.Different concentrations of hydrogen peroxide treatment significantly increased the superoxide dismutase activity,catalase activity,peroxidase activity and root respiration rate of Malus hupehensis Rehdseedlings,and greatly reduced the malondialdehyde activity.Compared with the old orchard soil,the application of 4.5%hydrogen peroxide（H3）has the largest increase,and its superoxide dismutase（SOD）increased by 602.2%,catalase（CAT）increased by 146.6%,peroxidase（POD）increased by 227.2%,and seedling root respiration rate increased by 96.4%,and its malondialdehyde（MDA）activity decreased by59.3%.5.Different concentrations of hydrogen peroxide treatment can change the photosynthetic parameters of Malus hupehensis Rehd.seedlings.Compared with the old orchard soil,the app-lication of 4.5%hydrogen peroxide treatment（H3）increased the most,and the basic paramet-ers of photosynthesis（net photosynthetic rate P_n,intercellular carbon dioxide concentration C-_i,transpiration rate T_rand stomatal conductance G_s）increased by 106.3%and 14.7%,respecti-vely.%,56.7%,and 81.8%,the chlorophyll a content increased by 40.0%,and the chlorophyl l b content increased by 79.3%.6.High-throughput sequencing assay data show dramatic changes in microbial community diversity.Compared with the old apple orchard soil,the application of 4.5%hydrogen peroxide（H3）has the most obvious change.Application of 4.5%hydrogen peroxide treatment（H3）and methyl bromide fumigation（CK2）have more similar soil dominance genus（Mortierella and Fusarium etc.）,and different from the old apple orchard soil（CK1）.The beneficial bacteria spores of 4.5%hydrogen peroxide treatment（H3）.The relative abundance of the enzyme genus increased by 160.25%,and the relative abundance of the harmful fungus Fusarium decreased by 70.5%.