Effect Of Different Strong Oxidizersr On Soil Environment And Seedings Growth Of Malus Hupehensis Rehd.Seedings Under Replanted Condition

Apple replant disease are common in major apple producing areas in the world,which seriously restricts the development of the global apple industry.In order to find an effective method to overcome the apple replant disease,this experiment took Malus.hupehensis Rehd.as the test material under potted conditions to explore the effects of replant soil treated with different strong oxidants on the growth and soil environment of Malus.hupehensis Rehd.seedlings.Five treatments were set up in the experiment: replant soil（CK）,peracetic acid（T1）,hydrogen peroxide（T2）,sodium hypochlorite（T3）,and potassium permanganate（T4）.The changes of soil enzyme activity,soil physicochemical properties,and replanted plant biomass were measured under different treatments,and it was confirmed that potassium permanganate had the best effect.On this basis,the effect of potassium permanganate on soil microorganisms was further studied.The main findings are as follows:In the pot experiment,except that after the sodium hypochlorite treatment,which caused the leaves to turn yellow,and the other strong oxidant treatments all effectively promoted the increase of the biomass of Malus hupehensis Rehd.seedlings.After potassium permanganate treatment,the plant height,ground diameter,fresh weight and dry weight of Malus hupehensis Rehd.seedlings in July 2019,August 2019 and September 2019 increased by 34.4,15.5,30.3and 2.32%;52.8,42.3,56.5 and 108.3% and 28.6,1.34,67.8 and 35.3% respectively compared with Malus hupehensis Rehd.seedlings in continuous cropping soil.Different strong oxidant treatments had different effects on the root system of Malus hupehensis Rehd.seedlings.In T1（peracetic acid）treatment,the root length,root surface area,root apex,root fork number and root respiration rate were 1.57,1.41,4.57,2.09 and 2.07 times higher than those in CK（replanting soil）,respectively;In T2（hydrogen peroxide）treatment,the root length,root surface area,root tip number,root fork number and root respiration rate were 1.53,1.31,3.95,2.56 and 1.48 times that of CK（replanting soil）,respectively.In T4（potassium permanganate）treatment,the root length,root surface area,root tip number,root fork number and root respiration rate were 1.67,1.88,3.57,2.62 and1.72 times higher than those of CK（replanting soil）,respectively.In T3（sodium hypochlorite）treatment,the root length,root surface area,root tip number,root fork number and root respiration rate were 1.02,0.80,1.28,0.97 and 1.12 times higher than those of CK（continuous cropping soil）,respectively.In conclusion,the effect of potassium permanganate treatment was the best.Different strong oxidant treatments reduced soil enzyme activities.In July 2021,the neutral phosphatase and sucrase activities were significantly decreased after potassium permanganate treatment.This is similar to the 2019 results.When potassium permanganate was added to the peat soil,it was found that the activities of neutral phosphatase,invertase and urease in the soil were significantly improved.Potassium permanganate treatment optimized the microbial community structure in replant soil.The relative abundances of Fusarium,Humicola and Mortierella decreased significantly.The post-combination treatment of potassium permanganate and peat soil promoted the recovery speed of soil microbial community and improved soil enzyme activity.