Effects Of Intercropping Against Apple Replant Disease In Old Apple Orchard

One year before the renovation and reconstruction of the aged apple orchard,trenches were dug and roots were cut within the row at a distance of 1 meter from the central trunk,and three crops were continuously planted between the rows.One year later,the aging fruit trees were removed and young trees were replanted.This study explores the impact of the above treatments on the soil environment of orchards and the effectiveness of preventing and controlling apple replant disease.The results are as follows:1.Continuous intercropping of Tagetes patula,Brassica juncea,and Triticum aestivum can improve the main soil enzyme activity.Compared with CK(aged apple orchard intercropping soil),the activities of soil urease,sucrase,phosphatase,and catalase increased by 55.56%,46.00%,30.72%,and 13.64% in T3(intercropping soil with Tagetes patula,Brassica juncea,and Triticum aestivum)treatment.2.Continuous intercropping of Tagetes patula,Brassica juncea,and Triticum aestivum reduced the content of root bark saponin,root bark extract,ferulic acid,and benzoic acid in the soil.Compared with CK(aged apple orchard intercropping soil),T3(intercropping soil with Tagetes patula,Brassica juncea,and Triticum aestivum)treatment resulted in a reduction of 64.41%,56.89%,61.29%,and 43.28% in the soil,respectively.3.Continuous intercropping of Tagetes patula,Brassica juncea,and Triticum aestivum significantly increased the number of cultivable bacteria in the soil,decreased the number of cultivable fungi,and changed the relative abundance of soil fungal communities.Compared with CK(aged apple orchard intercropping soil),T3(intercropping soil with Tagetes patula,Brassica juncea,and Triticum aestivum)treatment reduced the number of fungi in the soil by67.68%,increased the number of bacteria by 162.21%,and increased the bacterial/fungal ratio by 710.27%.It significantly reduced the relative abundance of Fusarium and Cryptococcus Saccharomyces,and increased the relative abundance of Mortierella.4.After continuous intercropping of Tagetes patula,Brassica juncea,and Triticum aestivum,the plant height,ground diameter,stem circumference,number of branches,and branch length of the replanted saplings increased to varying degrees.The plant height,ground diameter,stem circumference,number of branches,and branch length of the replanted saplings were 1.26,1.17,1.71,1.91,and 1.39 times higher than those without intercropping,respectively.5.The results of the pot experiment showed that in July 2022,compared with CK1(non intercropped soil),T(intercropped soil)had ammonium nitrogen,nitrate nitrogen,available phosphorus,available potassium,organic matter,and p H values 1.13,1.08,1.14,1.26,1.25,and 1.01 times higher than CK1,respectively.In August 2022,compared with CK1,T had1.12,1.09,1.11,1.29,1.32,and 1.08 times more ammonium nitrogen,nitrate nitrogen,available phosphorus,available potassium,organic matter,and p H in the soil,respectively.6.In September 2022,compared with CK1(non intercropped soil),the height,diameter,fresh weight,and dry weight of Malus hupehensis Rehd.Seedling in T(intercropped soil)were 1.13,1.15,1.19,and 1.13 times that of CK1,respectively;The root length,root surface area,root volume,and root tip number are 1.74,1.84,1.29,and 2.04 times that of CK1,respectively;The activities of root protective enzymes SOD,POD,CAT,and MDA content were 1.10,1.33,1.42,and 0.73 times higher than those of CK1,respectively.7.The root exudates of Brassica juncea can inhibit the growth of fungal hyphae caused by apple replant disease,such as Fusarium oxysporum,Fusarium moniliforme,Fusarium proliferatum and Fusarium solani.Its antibacterial component is dibutyl phthalate.