Three rice genotypes (Oryza sativa) were chosen, among some commercial cultivars and advanced lines, in order to evaluate the influence of nitrogen levels on leaf and panicle blast infection caused by Pyricularia grisea (Cooke) Sacc. Three genotypes El Paso 144 (EP), Don Ignacio (DI) and H 316-1-2-1-1 (H 316) under two nitrogen levels (without nitrogen and 150 kg N ha-1 as urea). Plants were inoculated on third leaf with a mixture of several insolates at a concentration of 1,2 x 10(5) hyphae fragments /ml and was incubated during 48 hours in a wet room. Leaf blast severity and lesion type, and panicle blast severity an incidence were evaluated. Data were analyzed by using ANOVA, and differences in means were compared by Tukey (p<0,05). Log-lineal models were applied with non-parametrical data. Genotype fertilization interaction in relation to leaf blast was not observed, at first shoot (M) and boot stages (D). Nitrogen fertilization increased leaf blast severity. Correlation between lesion type and percentage of leaf blast severity was high. Panicle blast severity was significantly reduced by N fertilization in genotypes EP and but not in H 316.
blast disease; nitrogen; Oryza sativa