Host-pathogen Relationship in Barley Scab

Abstract

The differentiation of physiological races in Fusarium graminearum SCHWABE, a causal fungus of barley scab was analyzed in this study. Twenty Fusarium strains collected from Japan and US from 1933 to 1985 (Table 1) were inoculated to 20 barley varieties sampled from about 5, 000 varieties of the world collection preserved in the Barley Germplasm Center, Okayama University (Table 2). "Cut-spike" inoculation method developed by the authors (TAKEDA and HETA 1989) was applied for evaluating the degree of virulence of the Fusarium strains and the degree of resistance of the barley varieties. At the flowering time, three spikes of each barley variety were cut and sprayed with the conidia suspension of each Fusarium strain, and they were kept in a phytotron where the temperature, humidity and light conditions were controlled. Thereafter the percentage of infected florets were recorded on the eighth day after inoculation. The experiment was replicated twice. For the statistical analyses, the percentage of infected florets was transformed into the degree of angle.