Studies On Biological Control Of Postharvest Diseases Of Kiwi-Fruits

Postharvest Diseases Of Kiwi-fruits was a serious problem in storage, because of the invading of the pathogens, kiwifruits depraved and then lost the commodity value and the value be used for food. At last caused obvious losses. Endophyic actinomycetes are abundant microbial resource. They produce active metabolizing substance and were important significance in biocontrol of plant disease.In this study 10 Endophytic actinomycetes were screened as biocontrol agent against postharvest diseases of Kiwi-fruits.1.Through the routine isolation, eleven strains were isolated from diseased fruits.Six strains were identifiedM1:M2[F.roseum(LK)S.etH.],M6[Geotrichum Candium],M7[F.oxysporum Schlecht.],M8[F.decemcellulare Brilc],M10[A.tenuis Nees],M12[Rhizopus rigricans Ehrenb]。Endophytic actinomycetes were screened as biocontrol agent againt Postharvest Diseases Of Kiwi-fruits,which causes enormous loses during storage and transport process and the conditions of fermentation were optimized.2.The identified pathogenic fungi were used as target pathogens to test the antagonistic capability of five actinomyces. The result demonstrated that five organisms having shown significant inhibiting effect most of the inhibiting effects beyond50% and some can reach 80%,germination of spores of target pathogens were suppressed obviously by the fermentation filtrate of them. Mixcultured respectively with five actinomyces respectively, target pathogens were inhibited by them the most effective agent was 91.5%.3.A modified"cross-plug"assay was used to identify the inhibition of 4 actinomyces to 5 fruit pathogens. The results indicated that the 5 strains have varying degrees inhibition to 5 fruit pathogens. The strain BAR1-5 has stable inhibition effect. The results shows that more than 70% inhibition ratio could be gained to M2,M7,M6 by GK and the inhibition ratio of X1 D3-2 are above 60%.Substrate mycelium of target pathogens suppressed with antagonistic actinomyces had been deformed or lysed and the degree of deformation were potentiated as prolonging the antagonistic. All tested actinomyces had represented persistent inhibiting effects on the target pathogens in different degrees and the same strain of actinomyces had different inhibiting categories of pathogens.4.The study showed that the fermentation broth of 5 actinomyces have different inhibition effective to different pathogenic fungi. The inhibition rate of GK toM7,M6,D3-2 to M30 X1 to M10 all surpassing 50% some can reached 60%.5.Optimized conditions for fermentation of four actinomyces were ascertained.The result showed that optimized mediums for strains D3-2,X1,BAR1-5,GK were number3,number7,number4,number1;pH were 7.5,7,8,6.5;and the fittest culture time for them were 96h,72h,96h,96h.