Relationship Between Pathogenicity Of Soybean Leaf Spot And Soybean Variety

Cercospora sojina is one kind of fungal diseases spread through the air and accurred in main soybean producing nations over the world. The pathogenic bacteria have the ability of variation and many pathogenic types in the field, which will cause some resistance decreased gradually, or even the totally loss of resistance. Therefore, the change rule of the pathogenic should be immediately clear. Because there are co evolutionary relationship between Cercospora sojina Hara and soybean varieties,which have been determined to major gene resistance in Genetics,it is important to study the interaction between pathogenic bacteria and soybean varieties. The population pathogenic variation of Cercospora sojina and the Identification of resistance of main soybean varieties, wild soybean varieties, Chinese and foreign soybean varieties have been studied in this paper, which used pot experiment andthe method of artificial inoculation.The following are the main results and conclusion of this study:1. Determine the pathogenic types of 144 varieties samples which collected from the main producing areas of soybean in Heilongjiang Province.And 14 physiologic races have been determined, they are NO.1, NO. 2, NO.3, NO.4, NO.5, NO.6, NO.7, NO.8, NO.11, NO.12, NO.13, NO.14, NO.15 and NO.16. NO.1and NO.3 are the regnant physiologic races of Heilongjiang Province, which have the same occurrence frequency of 12.58%.The next is NO.5, NO.15, NO.8, NO.12 and NO.2, the occurrence frequency is 11.94%,11.32%,10.69%,9.43% and 8.18%2. The 49 main varieties of soybean have low disease resistance against to the Cercospora sojina.The resistance frequency of Heinong 37 is 35%, which is the highest among all the soybean varieties. And the lowest are Heinong 52, Hefeng 25 and Suinong 15, the resistance frequency is 15%.3. The interaction between 99 soybean strains and Cercospora sojina Harashowed that the soybean strains have weak disease resistance,while the Cercospora sojina Hara have a high pathogenicity.4. According to the interaction relationship between 97 wild soybean varieties and 12 physiologic races(NO.1,NO.5~NO.15),there are 30 varieties resistance to 8 or more physiologic races, taking 30.92% of the materials under test,and there are 19 varieties susceptible to 8 or more physiologic races accounting for 19.59%. The race NO.1 is the highest virulence frequency and the lowest is the race NO.5.5. There are three high resistant strains among the 70 soybean germplasm resources in foreign countries which is WZ2, WZ7 and WZ13, there are 37 moderate resistance strains, which is the maximum and accounting for 52.85%.The next is the resistant varieties and susceptible varieties, which take the proportion of 34.29% and 8.57%.