The effect of a Pyricularia grisea Sacc. fungal filtrate growing in a liquid medium upon rice (Oryza sativa L.) seedlings and seeds

Abstract

Raw extracts of pure colonies of Pyricularia grisea fungus, of 60 days of incubation in 200 mL of Czapek liquid medium were used at different concentrations, on 30- day-old rice seedlings of IR-837 var. and in seeds from IR-837 and IR-759-54-2-2 cv., with the objective of proving their toxigenic power. Seedling symptoms consisted of progressive wilting twelve hours after they were placed in the filtrate and they were directly related with the concentration. There was an inhibiting action of the filtrate and its dilutions on rice seed germination in both varieties, which is in correspondance with the concentration, although there were not statistically significant differences among treatments. The different filtrate concentrations influenced seedling height and root length, that was inhibited under the action of the pure filtrate, but increasing with concentration decrement in the susceptible variety, although there were no statistically significant differences. Results proved that the fungus produces toxic substances in Czapek culture medium.