| Nowadays Ricinus communis wilt is one of the most soil-borne diseases for castor oil plant, which could lead to the underproduction of caster oil plant by 20%～30%,the worse field by 50%～60%,and even no production, which result in enormous economical lost .Until now there is no report of biocontrol methods and functional mechanism of Ricinus communis wilt .In order to effectively control the occurrence and harmness of Ricinus communis wilt ,this paper showed a rather systematic study on the controling effect and mechanism of Trichoderma spp.The main composition of which is T.harziann,L20 and L30 on Ticinus communis wilt. At the same time, this paper made the first attempt on the function of degradation of T.hanzianum on F.oxysprum thick toxin.The Trichoderma spp. on Ricinus. The paper also made clear that the functional mechanism of the Frichoderma spp. Control on Ricinus communis wilt had a relationship with the competition, hypen parasitism and lysis of pathosen hyphae of T.harzinum L20 and L30. Therefore, it provided a theoretical basis for field application of Trichoderma spp.Obtaining the antagonistic strains and soil sample from different depth in Tongyu of Jilin Province, we adopted Orthodox Tissne isolation method and the dilution-plat in method to get the pathogenic bacterium and biocontrol microorganism from infected plant and soil. After the seperation, the pathogenic bacterium confrontedlly. By separation, we gottwo strains of Trichoderma spp. which could prevent and control Ricinus communis wilt rather effectively. By prelimary judgement from morphology, the two strains of Trichoderma spp. More identified as T.harzianum and named L20 and L30.From the biology character study on the T.harzianum. the results showed the development of hyphae spore yield were under 30℃～35℃,when the Ph value is 2～11.Under the Ph value of 5～9,they could grow the fastest and yield spore most .There was no obvious effect of sunlight on the growth of T.harzianum, the colony will growfastest if the 24-hour full sunlight,the spore yield will be the most one as well.There was some difference between the biological character of the seperated T.harzinum and some related report about T.harzianum. The reported T.hanzainum could grow well under the temperature of 25℃～30℃,when the Phvalue is about 5.0.The results showed that T.harzianum L20 and L30,grow quite fast and strongly competitive.7～10d could recover the pathogenic bacterium colony and at the same time. They had strong antibiosis function on Ricinus communis wilt. The biocontrol Trichoderma spp. Which is produced from T.harzianum L20～L30 was planted for an experiment .The control effect on Ricinus communis wilt is 75.0% and 68.8%, respectively. The study also made clear for the best usage and the most proper dosafe of Trichoderma spp. which provides the ideal environmental conditional for the living and of different pathogens. This study provides that it has ideal biocontrol effect to Ricinus communis wilt by method of hole application and mixing soil.Among the antibiosis functions of T.richoclerma spp. on different pathogens, competition and hyper parasitism functional mechanism are theimportant ones. The studying results showed that during the processes of competition and hyper parasitism mechanisms ,some important resoluase are produced ,such as Chitinase, fiber enzyme,protease etc. Implanting the spores of Ricinus Communis will respectively into Chitinase. The fiber enzyme and protease. Observing pathogen spore's germination pathogen spore of T.harzianum did not germinate. Just with naked eye orange-red sediment could be observed ,and the pathogen spore in fiber enzyme and protease began to germinate.Adopting Divert viewing and accurate method of reventing sugar of determination to three kinds of enzyme activity of thus two strains T.hanzainum.The result showed that the enzyme activity of the identical strain at the different fermeatation time were different enzyme activity was not stable tracts from inside-spore and outside-spore of T.harzianum to deal with. F.oxysprum thick toxin,and putting sorghum seeds into the mixed treatment liquid in the greenhouse of 25℃,we observed the growth after 5d. The results showed that the root system of sorghum grew well and showed no disease symptom . This proved that toxin lost its growing–resistance function.
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