Root-invading Fungi Of Common Vetch (Vicia Sativa) At Different Growth Stages

Root-invading fungi of common vetch(Vicia sativa)were studied in Qinghai-Tibet Plateau,Gansu province,China.Roots of V.sativa were sampled at Seedling,Branching,Flowering and Maturity stages in the year 2017 and 2018,respectively.Fungi were isolated and identified from 4 common vetch cultivars,Lanjian No.1,Lanjian No.2,Lanjian No.3 and 333/A.Pathogenicity and the effects of these root-invading fungi on common vetch growth and forage value were determined.The results as follows,A total of 35 fungal species belonging to 23 general were isolated from the field and greenhouse experiments,of which,30 fungal species belonging to 22 genera were isolated and identified from field.For the field research,18 fungi were isolated from Lanjian No.1,19 fungi from Lanjian No.2,twenty two fungi from Lanjian No.3 and 17 fungi from 333/A.Among these fungi isolated 12 species were shared by 4 V.sativa cultivars.They were Ascobolus sp.,Aspergillus niger,Fusarium acuminatum,F.solani,F.trichothecioides,F.tricinetum,F.avenaceum,Microdochium tabacinum,Rhizoctonia solani,Mortierella alpine,Phoma multirosta and Lectera colletotrichoides.Except for F.avenaceum,the percentage of other fungi isolation were more than 1.25%.F.equiseti,Humicila grisea,Paraphoma chrysanthemicola,Paraphoma sp.and Penicillium sp.were only isolated from the greenhouse research.The major root-invading fungi in 4 V.sativa cultivars were differed.The most common 5 fungal species from Lanjian No.1,in order of decrease frequency of isolation were Mortierella alpina(19.5%),Phoma multirostrata(17.62%),Ascobolus sp.(17.59%),Lectera colletotrichoides(11.5%)and F.avenaceum(10.62%).And Pythium recalcitrans was only isolated roots of Lanjian No.1.The most common 5 fungal species from Lanjian No.2,in order of decrease frequency of isolation were Mortierella alpina(16.62%),Rhizoctonia solani(14.7%),F.tricinetum(14.33%),F.avenaceum(13.91%)and F.acuminatum(11.06%).Wardomyces inflatus,Cladosporium uissimum,Phoma medicaginis and Myrothecium roridum were only isolated from roots of Lanjian No.2.The most common 5 fungal species from Lanjian No.3,in order of decrease frequency of isolation were Ascobolus sp.(39.91%),F.acuminatum(19.26%),Mortierella alpina(18.84%),F.tricinetum(17.83%)and R.solani(13.54%).And Alternaria japonica,Aspergillus oryzae,Dendryphion nanum,Odendron cerealis,Paecilomyces marquandii and Volutella ciliata were the 6 fungal species that were only isolated from the roots of Lanjian No.3.The most common 5 fungal species from 333/A,in order of decrease frequency of isolation were Ascobolus sp.(21.7%),F.acuminatum(17.14%),Mortierella alpina(14.56%),R.solani(13.94%)and F.trichothecioides(12.5%).As common vetch growing from Spring to Autumn,the percentage of fungal isolation from the plants roots were firstly increased,and then decreased.The percentage of fungal isolation of common vetch at Seedling,Branching,Flowering and Maturity were 25.47%,68.65%,71.48% and 61.33%,respectively.During the growth stages of V.sativa,21 fungi were isolated from Seedling stage,10 fungi from Branching stage,8 fungi from Flowering stage and 10 fungi from Maturity stage.The fungi that were shared by 4 growth stages were R.solani,M.tabacinum,F.acuminatum and F.tricinetum.Principal Component Analysis(PCA)showed that the percentage of fungal isolation was positively correlated with temperature.The Pathogenicity test results showed that F.oxysporum,F.avenaceum,F.acuminatum,F.tricinctum,Paraphoma chrysanthemicola,M.tabacinum,R.solani,Alternaria solani,Clonostachys rosea and Myrothecium roridum were the 10 fungi with the strongest pathogenicity to the four common vetches.The incidence of disease ranged from 33% ~ 100%,and the disease index ranged from 8 ~ 100.The pathogenicity of the 10 fungi with the strongest pathogenicity were further studied under greenhouse conditions.These fungi cause moulding,wilting and visible lesions on the common vetch roots.Disease index were 16 ~ 53.1,plant length and root length decreased between 1.3% ~ 26.5% and 4.3% ~ 14.3% respectively,root dry matter content decreased by 4.8% ~ 60.9%,chlorophyll content decreased by 12.5% ~ 30.3%,root activity decreased by 15.5% ~ 92.3%.The infection of Rhizoctonia solani and Microdochium tabacinum mostly significantly decreased crude protein and crude fat of common vetch.