divulgação (1)Prelecionista: Gustavo Bilibio dos Santos; Data: 19/07/2022, às 14h, via Zoom*; Orientador: Emerson Medeiros Del Ponte

Resumo:  Wheat head blast (WHB) is one of the most important diseases of wheat. It is caused by the Pyricularia oryzae Triticum pathotype. First reported in 1985 in the state of Paraná, WHB has limited the expansion of wheat in the Brazilian Cerrado biome. In this work, data from wheat yield (Y) and WHB intensity under natural epidemics were collected from two sources: the UFTs data, which is a cooperative network of fungicide trials, and the EPAMIG data, where experiments were conducted to evaluate the effect of sowing dates on the wheat blast and yield. Three analyzes were conducted. First, the relationship between incidence (I) and severity (S) was studied using an ordinal linear regression model at the complementary log-log transformation of data. The Pearson correlation (r) analysis of the disease variables and yield was estimated using a meta-analytic approach for the Fisher’s Z transformation of r. The relationship between WHB intensity and Y was studied based on a random coefficients model fitted to the WHB intensity data and the log-transformed data of Y. The I-S relationship was well explained by the CLL model. The population average intercept and slope for the UFT were -1.467 and 1.614 and were -0.820 and 1.028 for the EPAMIG. The estimated value of I when the S reached 10% for the UFT and EPAMIG data sets were 46% and 22% respectively. The r for all intensity measures was negative. The highest estimated r by the meta-analysis was rI = -0.92 followed by rS = -0.90. The population average estimated intercept and slope for the WHB intensity and Y relationships were 7.798 and -0.020 for the I-Y and 7.721 and -0.030 for the S-Y relationship. The estimated relative yield loss when I and S reached 10% were 18.38% and 26.10% respectively. In our study, we were able to explore some important relationships of the WHB pathosystem and improve the epidemiological knowledge about the disease.

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