Selection of genotypes for quantitative resistance to oat crown rust, based on its components, needs the knowledge of the association of these components with each other and with the amount of disease in the field, represented by AUDPC. This work aimed to determine these correlations, based on results of previous trials, in which the reaction of 31 white oat genotypes was tested and the resistance components were quantified. Correlations were usually low for the resistance components with each other and for these components with the amount of disease in the field. Higher correlations, consistent among years, with AUDPC were infection frequency in seedlings and latent period and pustule size in adult plants. All other possible correlations were very low. These data suggest that the resistance components mentioned can influence the expression of quantitative resistance in the field in a somewhat important manner. Nevertheless, the low correlation of resistance components with each other indicates that genotype selection, in this host-pathogen interaction, must not be based on a single resistance component assessment. The correlation analysis suggests that the expression of quantitative resistance to oat crown rust is not conditioned by a single resistance component but by the group effect of all of them. In addition, it is possible that different mechanisms are involved for each genotype, in such a way that the more important resistance component in one genotype may not be the same for another.
