Abstract
Resistance of five or ten rice varieties to lesion formation and to sporulation of three blast fungus strains on host plants was tested in a greenhouse. Varietal difference of resistance to sporulation was found in a few experiments, but varietal difference of resistance to lesion formation was difficult to find, because of a large variation of pathogenicity index (aggressiveness) by which varietal resistance was estimated. However, correlation of field resistance was higher with resistance to lesion formation than with resistance to sporulation. Correlation between resistance to lesion formation and that to sporulation was not found.
