The Study On Antagonism Against Alternaria Solani And Control Of Potato Early Blight By The Fermentation Of Trichoderma T-115D

Using antagonistic microorganisms to control plant diseases is an important method not only non influence to the environment and human health and also potato non produce resistance to A. solani. The inhibition and mechanism of Trichoderma T-115D against Alternaria solani and obtained were studied in this paper. The conclusions were as follows:1. The studies of antimicrobial spectrum of Trichoderma T-115D showed that the fermentation of Trichoderma T-115D could inhibite 10 kinds of pathogens in different degree. The inhibition against Phytophthora was the best of all, and the inhibition rate was 70.0% in the 10 times dilute solution. It could also inhibit A. solani, Cytospora chrysosperm and so on. The inhibition rate reached to more than 50%, but less than 50% to inhibite Bipolaris sorokiniana, Fusarium solani and Pyricularia grisea. The results of confronted culture showed that Trichoderma T-115D grew rapidly, could occupy most of the space and had strongly competition than the pathogens.2. Through the research of Trichoderma T-115D fermentation conditions, the most suitable medium was PD for Trichoderma T-115D growth and metabolism The optimum fermentation conditions for Trichoderma T-115D in PD medium were the initial pH 6.0, 25℃, 150 r·min-1 for shaking speed, and more than 7 days for fermentation.3. Trichoderma T-115D grew rapidly, then occupied most of the space and eventually covered A. solani in confronted culture between A. solani and Trichoderma T-115D. It indicated that the competition was one of the antagonism mechanisms of Trichoderma T-115D, and Trichoderma T-115D could parasitize A. solani Trichoderma T-115D spiraled up binding with the hyphae of A. solani under microscope, it demonstrated that Trichoderma T-115D could parasitize A. solani.4. The fermentation of Trichoderma T-115D could inhibit growth of Trichoderma T-115D, and inhibition rate increased as the fermentation content increased. The fermentation could also strongly inhibite spore of A. solani germination, the inhibition rate was 100%.5. The fermented liquid of Trichoderma T-115D could prevent potato early blight. When spraying with fermented liquid of Trichoderma T-115D in vitro potatoes leaves firstly and inoculating the spore suspension on second day, and the control effect of fermenting stock solution was the best. The control effect of fermenting stock solution was 67.0% when inoculated with 104 spore every milliliter, it could be 63.3% when inoculated with 2.0×104, it could be 62.5% when inoculated with 5.0×104. As the lower concentration of fermented liquid leakage, the results were worse. When inoculating the spore suspension first and spraying fermented liquid of Trichoderma T-115D the next day, the effect to prevent potato early blight was be significantt. The control effect of fermenting stock solution was 57.1% when inoculated with 1.0×104 spore every milliliter, it could be 50.0% when inoculated with 2.0×104 and it could be 42.0% when inoculated with 5.0×104. It showed that the fermented liquid of Trichoderma T-115D could prevent potato early blight. Using the method of soaking potato tuber could prevent the happen of early blight, and the effece was better as the longer time soaking. The control effect could be 42.0% with soaking 5 hours.6. The results of treatments in the live leaves showed that the Trichoderma T-115D fermentation had a significant effect of prevention. Spraying Trichoderma T-115D stock fermentation firstly, the control effect could be 41.7% in variety Dongnong 303, and when the fermentation diluted was 10 times the control effect could be 13.9% . Inoculating the spore suspension firstly, the control effect would be 26.4% in Dongnong 303, and when the fermentation diluted was 10 times the control effect could be 6.1%. Using the method of watering Trichoderma T-115D fermentation could increase the potato plants'height, fresh and dry weight. The results was better as the more water content. With watering 250 milliliter Trichoderma T-115D fermentation, the plant could be more 6.6 millimeter than the contrast, fresh weight increased 0.912 gram and the dry weight increased 0.09 gram.