. The overgrowth curve has a positive, decreasing slope at higher inoculum concentrations (5.0 × 1010 1.0 × 1010 conidia/ml). This decrease in slope means that after a certain level of inoculum
concentration the acceleration of OGR decreases. Hormones in higher concentrations showed
similar pattern. Almost the same pattern of effect was observed in ASS (Fig.1). Therefore, the
growth promoting factor present in the spore suspension was heat resistant. It should be mentioned
that GAs also shows similar effect which might replace spore suspension in testing the
susceptibility of rice varieties against bakanae disease. In China, Ma et al. (2008) obtained a
significant correlation between the length of the seedling treated with GA3 and disease injury by
bakanae fungus.