Identification Of Pratylenchus Species Of Sweet Potato And Screening Of Resistant Cutivars

Root-lesion nematodes of the genus Pratylenchus Filipjev,it rank second only to Root-knot and Cyst nematodes in terms of their worldwide economic impaction on crops.Being migratory endoparasites,Pratylenchus spp.caused severe root damage on a wide range of crops while feeding primarily in the cortical parenchyma.As migratory endoparasites,these nematodes destroy tissues of the root system,causing surface cracking and internal rotting of tubers and predisposing the parasitised tissues to secondary infections by fungi and bacteria.Reduction in the quantity of feeder roots usually results in a general loss of vigour and yield in sweet potato.Reports on the control aspects of Pratylenchus spp in recent years have focused on the screening of nematicides.This test focused on the screening of resistant cultivars in a field,different from other means such as nematicides,the resistance screening was not only cost-effective but also met the essential requirements of The Green Development.The main work and conclusions were listed as follows:1.Root-lesion nematodes of Guogou Village(Yangqiao Town,Linquan County,Fuyang City,Anhui Province,115 ° 24 ′ 37 ″E,32 ° 59 ′ 7 ″N,Altitude 30m)were identified as Pratylenchus brachyurus,Pratylenchus coffeae and Pratylenchus delattrei.Pratylenchus coffeae is the dominant species.The initial density of root-lesion nematode in Guo Gou Village ranged from 11 to 25 strips/100 g weight soil and reached the hazard threshold,which was investigated by field sampling.2.The increase of root lesion nematode density led to what the diversity of soil nematodes decreased in Guogou village.The relationship between root-lesion nematode density and soil nematode community diversity was a significant negative correlation(r =-0.61,P<0.05).We believed that the main reason for the deterioration of soil nematode microecology was the increase of root lesion nematode density.3.Immunized cultivars and highly resistant cultivars were not found,Four moderately resistant sweet potato cultivars,longshu19,shangshu19,yanshu25 and fushu24,were tested in a field repeat over 2 years.The control efficacy differed significantly among resistant cultivars.The medium resistance control effection of longshu19 was 82%,shangshu19 was 35%,longshu25 was 83%,and fushu24 was 27%.We suggested that these4 moderately resistant sweet potato cultivars can be cultivated in areas where root lesion nematode occurrence is severe.4.A significant positive correlation(r = 0.79,P<0.01)was found between the field resistance indicator and decay level of sweet potato,based on statistical analysis of the data.Fusarium was identified on the surface of rotten sweet potato.The nematodes in rotten sweet potato were mainly fungivores nematodes of the Tylenchida and Aphelenchida,Root lesion nematode and other plant parasitic nematodes were not found.Therefore,we believed that the harm of root lesion nematode to sweet potato do not just occured during the reproductive period,and the mechanical injury caused by style provided convenience for the parasitization of fungi,which ultimately led to aggravation of decay during sweet potato brewing,so planting medium resistant sweet potato cultivars can reduce the risk of the occurrence of sweet potato decay during the brewing period.As reviewed in,the screening of resistant cultivars in the field has some production significance and provides a theoretical basis and reference for searching for resistance genes and conducting studies on resistance mechanisms.