Identification Of Common Fungi Diseases Of Dendrobium Candidum And Study On The Application Of Compound Microorganism Inoculant

There are many fungi diseases of Dendrobium candidum Wall.ex Lindl planting,but available literature has not investigated the compound biological resistance on common fungi diseases of Dendrobium candidum.Therefore,to evaluate the biocontrol activity of Gab-1/2 on Dendrobium candidum fungal disease,this preliminary study was carried out in three main aspects:(1)Isolation and identification of the pathogens of common fungi diseases of Dendrobium candidum,and investigate for the biological characteristics of the pathogens and the sensitivity on some fungicides.(2)In vitro determination of inhibition activities and disease resistance in greenhouse of compound microorganism inoculants Gab-1/2.(3)Growth-promoting effect of Gab-1/2 on Dendrobium candidum,and the biocontrol ability of the compound fungus was evaluated comprehensively.The main results are as follows:(1)In this study,four strains of pathogenic fungi were isolated from samples of Dendrobium candidum by tissue separation,numbered with SHYM-2,SHTJ,SHJF and SHHB.Through morphological observation,pathogenicity determination and ITS sequence analysis,SHYM-2 was identified as Phytoppthora palmivora,SHTJ was identified as Colletotrichum gloeosporides,SHJF was identified as Fusarium oxysporum,and SHHB was identified as Alternaria tenuissima.(2)Through the identification of single bacteria biocontrol ability,two biocontrol strains Gab-1(Paenibacillus polymyxa)and Gab-2(Bacillus subtilis)showed high antibacterial activity against four pathogens,and the highest inhibitory rate was 82.1%.Thus,the two strains were selected as candidate strains for the compound microorganism inoculants.Neither Gab-1 nor Gab-2 inhibited the function of each other,and could be used as compatible combination.The combination of two biocontrol bacteria revealed the compound effect of P.polymyxa and B.subtilis,and finally the compound composition of microorganism inoculant was constructed.(3)Through disease resistance determination in greenhouse of compound microorganism inoculants Gab-1/2,the result showed that,with the extension of application time,the improved control effects were at different levels.The observed control effect on P.palmivora,C.gloeosporides,F.oxysporum,A.tenuissim when compared to that of agricultural chemicals wre 77.6%,78.2%,0%,78.2%,respectively.(4)Through the determination of agronomic characters of Dendrobium candidum with Gab-1/2 application after eight month,the result showed that it has a role in promoting growth of plants: the combination of two biocontrol bacteria can affect the formation of the ground roots of Dendrobium candidum;can promote the growth of roots,stems and leaves,and can significantly increase branch number,plant height,underground root volume and fresh weight.Gab-1/2 does not only control the common fungal diseases and promote the growth of Dendrobium candidum,but also have certain application value and significant potency.