Studies On Resistance Mechanisms Of Gentian To Septoria Micropora Speg. And Control Methods Of The Disease

The paper identified the pathogen causing Gentian leaf spot, which was epidemic in Heilongjiang province, and evaluated the resistance level of Gentiaca scabra and Gentiaca manshurica, also analysed the relationship between morphology, physiological indicators and resistance, studied control methods for the disease. The results were summarized as follows:The pathogen causing Gentian leaf spot, which was epidemic in Heilongjiang province was Septoria gentiacae Thum. and Septoria micropora Speg..The resistance of Gentiaca manshurica was higher than that of Gentiaca scabra significantly.Results indicated that enzyme activity of Gentiaca manshurica was all higher than that of Gentiaca scabra before and after inoculation, especially PPO activity, PAL activity could be recognized as indicators to identify the resistance of Gentian to Gentian leaf spot. After inoculation, the pathogen induced PPO activity peak appearing firstly in the two varieties, PAL later, and then POD.Soluble protein content of healthy Gentiaca manshurica was lower than that of healthy Gentiaca scabra, Comparing with Gentiaca scabra, Gentiaca manshurica's soluble protein content changing range was relative smaller following inoculation.Gentiaca scabra's soluble sugar content was higher than Gentiaca manshurica's in healthy plant, it was propitious to pathogen invading , Gentiaca manshurica's soluble sugar content descended sharply after inoculation, so we could roughly consider Gentian leaf spot was a high sugar disease.In the whole disease process, Gentiaca manshurica's chlorophyll a and b content were always higher than that of Gentiaca scabra of the same phases .Results indicated that Gentiaca manshurica's some morphologic characters, such as height being rather short, ramification being few and leaf being narrow, leaf surface being lubricant et al , were all disadvantageous for spore's locating and germinating, so these characters exerted important function on resistance.Inhibiting fungus experiment screened out three fungicides, whose inhibitory effect for Septoria micropora was outstanding, and four better than others .There were four fungicides whose effect were rather better than others in fungicides effect experiment, especially Yebingkang was the best among the tested fungicides , and it's control effect was 69.05 percent in prophasco Ls-1 was provided with potential of being exploited into high effect fungicide for Septoria micropora, and it still awaited more study.Result of planting treatment experiment indicated that one treatment combination wasrelatively ideal, that was treating seedling with fungicide, intercropping with maize and cleaning up field remains; but the highest effect of the treatment was no more than 48.25%.