Investigationon Leaf Spot Disease With Its Identification Of Resistance,beetles Damage And Rootsystemin Several Eriobotrya Species And Interspecific Hybrids

Three aspects,namely loquat leaf spot disease harm,beetle harm and root system comparison are included in this study.Loquat leaf spot disease is the most common disease in the production of loquat,in which the loquat gray spot has a direct impact on the fruit,and the trunk is susceptible to the beetleswhich seriously harm the tree vigor.In addition,the root of cultivated loquat is not strong enough to the stress resistance of loquat and the absorption of fertilizer.All three aspects affect the yield and quality of loquat.It is a vital and basic work to screen loquat germplasm with strong resistance to pests and diseases for loquat? genetic improvement.Based on the diversity of germplasm resources,we used 26 species of Eriobotrya and 8 interspecific hybrids as materials,evaluated pest resistance and stress resistance of loquat germplasm resourcesfrom the natural incidence of investigation of the leaf spot disease,indoor artificial inoculation of gray spot disease,beetle hazard investigation,pest and disease control,observingroot growth and so on.In theory and practice,it provides scientific basis for controlling loquat leaf spot and beetles,and provides reference for the study of loquat resistance and root stress resistance.The results are as follows:(1)According to the leaf spot disease investigation among different types of germplasm resources loquats,the ranging of resistance to leaf spot from strong to weak are wild loquat,cultivated hybrid loquat,and cultivated loquat varieties.(2)According to the leaf spot disease resistance grading standard,221 loquat materials were evaluated,including 9 high resistant materials,30 resistant materials,36 moderate resistant materials,25 susceptible materials and 121 high susceptible materials.The high resistant and resistant materials of wild loquat accounted for 54.24%,while the hybrid loquat only 4.32%,showing the wild loquat resources is very rich in the leaf spot resistance.According to their corresponding disease index,the higher resistance to leaf spot of wild loquats are: E.fulvicoma W.Y.Chun ex W.B.Liao et al.,E.salwinensis Hand-Mazz,E.fragrans Champ,E.deflexa f.koshunensis Nakai,E.petiolata Hook.and E.malipoensis Kuan.In the hybrid loquats,E.deflexa f.koshunensis Nakai and E.deflexa f.buisanensis Nakai which are highly resistant to leaf spot disease with their respective hybrid progeny‘Jiefangzhong'× E.deflexa f.koshunensis Nakai,‘Dahongpao'× E.deflexa f.buisanensis Nakai still showed resistance to leaf spot disease.It is inferred that wild loquat may inherit its leaf spot resistance to its offspring.(3)In 25 kinds of loquat materials,most of them being wild loquat,according to the results of indoor artificial vaccination of the pathogen of loquat gray leaf spot,that is Pestalotiopsis eriobotrifolia,it indicated that the high resistance to loquat gray spot disease species are 8 kinds,they are E.fragrans C hamp,Photinia serrulata Lindl.,E.malipoensis Kuan,E.henryi Nakai,E.bengalensis f.Hook.,E.obovata W.W.Smith,E.deflexa f.koshunensis Nakai.;the resistant kinds are E.elliptica Lindl.and E.prinoides Rehd.& Wils× ?Jiefangzhong?.Among 25 kinds,there are 15 kinds of moderate resistant and higher resistant species,which accounts for 60.0% and is valuable material for carrying out the resistance of gray spot disease breeding.The results of the indoor test of gray spot disease were consistent with those in the field.(4)The investigation of the beetles harm to loquat indicates that wild loquat materials owns the highest proportion of 77.42% in the anti-beetles(Apriona germari Hope),is 5 times of cultivars;the types of anti-beetles loquat species from strong to weak are also wild loquat,variety of hybrid offspring loquat,interspecific hybrids,cultivars.The anti-beetles loquat species are E.bengalensis f.Hook.,E.cavaleriei Rehd.,E.deflexa Nakai,E.deflexa f.koshunensis Nakai,E.fragrans Champ,E.henryi Nakai,E.kwangsiensis Chun,E.malipoensis K uan,E.obovata W.W.Smith,E.× daduheensis H.Z.Zhang ex W.B.Liao et al.,E.prinoides var.laotica Vidal,E.salwinensis Hand-Mazz,E.sp?,E.fulvicoma W.Y.Chun ex W.B.Liao et al.,?ZaozhongNo.6?×E.deflexa f.koshunensis Nakai and ?Dahongpao?×E.deflexa f.buisanensis Nakai.In this study,have compared the two methods of prevention and control to beetles,chemical control and hook beetle larvaes,the later was better,but the two methods were both inadequate.(5)According to the root growth of E.malipoensis Kuan,it shows that there is a rapid root growth stage from 9 months to 19 months after being planted,but the specific growth point remains to be further studied.The root system of different types of loquats which were grown for 6 months and 9 months showed that the five most powerful roots of wild species are E.malipoensis Kuan,E.japonica Lindl.,E.obovata W.W.Smith,E.henryi Nakai,and E.× daduheensis H.Z.Zhang ex W.B.Liao et al.