Analysis Of Soil Fungi Community Structure In Continuous Cropping Apple Of Loess Plateau In Northwest China

The experiment was conducted from August 2016 to March 2018 in the College of Horticultural Science and Engineering of Shandong Agricultural University and the National Experimental Station of the Apple Engineering Technology Research Center.Soil samples were collected from 20 continuous cropping orchards in 3 provinces of Shanxi,Gansu,Jin and Jin.The fungal community structure of apple continuous cropping soil in the Loess Plateau of Northwest China was studied by constructing and analyzing the continuous soil fungal clone library combined with T-RFLP technology.The seedlings of Malus hupehensis Rehd.were used as the test materials.The correlation between the growth of continuous cropping plants and the genus of dominant fungi in the soil was studied under potting conditions,and the types of major harmful fungi that caused the continuous cropping of apple in the Loess Plateau in Northwest China were identified.Regional prevention and control of apple continuous cropping obstacles provide a theoretical basis.The main findings are as follows:1.In terms of the classification level of the gate,Ascomycota is the main fungal type in the Loess Plateau region of the northwest and is found in all soil samples.The proportions of Ascomycetes in the 20 orchards were 72.31 %,67.90 %,84.51 %,57.14 %,49.37 %,80.43%,28.04 %,82.19 %,54.12 %,94.44 %,55.26 %,30.97 %,70.64 %,50.62 %,77.42 %,80.36 %,80.00 %,9.09 %,80.88 %? 76.74 %,respectively.Especially,the proportion of Ascomycota in the area of 10(Fuping)was as high as 94.44%;in the category of genus,Fusarium,Mortierella,Chaetomium,Cryptococcus were the main dominant flora in the Northwest Loess Plateau.The Fusarium spp.is present in almost every region and has a high abundance,especially in 2(Qinzhou),6(Liquan),8(binxian),10(Fuping),15(pinglu)and 16(In the Xiangcheng area,the relative abundances accounted for 30.86%,53.26%,57.53%,90.74%,41.94%,and 50.00%,respectively.2.Judging from the provinces to which the orchards belong,the five regions in Gansu Province have relatively high diversity index,evenness index,richness index and relatively low dominance index.The research results also showed that apple continuous cropping obstacles were severe in Shanxi Fuping,Pinglu Shanxi,and Shanxi Salt Lake districts.The fresh weight inhibition rates were 160%,107%,and 175%,respectively,and the abundance ofFusarium spp.was high,which was 90.74 % respectively.,41.94%,51.01%;Qingshui,Zhuanglang,Handan,Liquan,Qianxian,Baishui,and Jixian have a moderate degree of continuous cropping obstacles,with a fresh weight inhibition rate of 79%,79%,88%,54%,76%,71%,64%;Qinzhou,Jingning,Binxian,Xunyan,Huangling,Luochuan,Fuxian,Fucheng,Linyi,Wanrong appear to be low The fresh weight inhibition rates were 16%,20%,25%,8%,3%,6%,25%,15%,47%,and 11%,respectively.3.From the correlation between the inhibition of seedling growth and the dominant fungal genera in the soil,the abundance of Fusarium spp.was significantly positively correlated with the severity of apple continuous cropping obstacles(r=0.585,p<0.01).There was a significant negative correlation between the abundance of molds and the severity of continuous cropping disorders in apple(r=-0.473,p<0.05).