Study On Aggregation Index Analysis Of Wheat Variety And Race Of Puccinia Striiformis West. And Race Dynamic Forecast

The data of planting acreages of wheat variety and occurring frequency of physiological race of Puccinia striiformis West, from 1975 to 2000 were collected and analyzed. Aggregation index was employed to characterize wheat variety and race population and their spatio-temporal relationship. By using hill plot nurseries inoculated with single race, by analyzing the historical data of varieties resistance to physiological race P. striiformis and by expert evaluation, the applicable relative parasitic fitness of P. striformis was obtained. Based on these data, a model of interaction between multi-variety and multi-race, named CRDM was established to explore the likelihood of predicting the dynamics of wheat yellow rust fungi.The detail results are as follows:1. After comparing several kinds of aggregation index, a new aggregation index, Ai, was defined by the square of mean and standard variance of the 10 foremost races sorted by the occurring frequency.That is Ai = M . S . The index was not affected by "other race and pathotype" in detecting data of P. striiformis race population and could better reflect the degree of aggregation of race population.2. The temporal sequence relationship of race aggregation curve among Gansu, Henan, Hubei, Shandong, Sichuan and Shanxi province and between wheat variety and race were analyzed by using correlation method. The results showed Gansu province where P. striiformis could easily mutate was the source place of new physiological races. Wheat variety aggregation affected race aggregation, but the race aggregation lagged behind wheat variety, for example, two years in Gansu province.3. By using the data of field experiment and historical accumulation of wheat variety resistance, the 2152 combinations' relative parasitic fitness among 192 variety * 24 races were figured out by the method of complex disease index. In addition, experts of wheat yellow rust disease estimated the rest of the combinations. In this experiment, we explored some methods to using historical data. At the same time, several methods were tried to achieve more applicable data, which established a solid ground for CRDM.4. CRDM, a model of interaction between multi-variety and multi-race was established. The data of the historical race of wheat yellow rust disease, the planting acreages of the main 192 wheat cultivars and the relative fitness of 192 varieties * 24 main races or pathotypes were input into this model, and then, using Visual basic 6.0 to program this model and to simulate the frequency change of all the races with the cultivar database, the fitness database and the race frequency database. The preliminary running results showed that this model can predit the trend of race occurring frequency, although its structure was simple. The most important was to continue filling the relative parasitic fitness database.