Pyricularia grisea Cavara, the cause of rice blast, is one of the most important fungal pathogens of rice due to its widespread occurrence and destructive nature (Ou, 1985). The fungus can attack any aerial part of the rice plant, including seeds, inwhich the fungus may over winter for several years (Ito, 1932 and Manandhar, 1996). For creating disease epiphytotics, suspension containing adequate number of conidia is required. This pathogen requires a set of conditions for its growth and sporulationincluding the composition of culture media, temperature and light (Cruz et al, 2009). Although Pyricularia grows well on most of the media, but it does not sporulate well. So the present study was carried out to find out suitable medium which will induce better sporulation of Pyricularia grisea irrespective of the light conditions and pH of the medium. Eleven different natural media based on makra grass {Eleusine indica), carrot cubes, banana leaves, banana petioles, Acrachne grass (Acrachne racemosa),rice husk, rice straw, bajra grains, rye grains, oat grains and barley grains were tried. The flasks containing the substrate were autoclaved twice at 121.6°C for 20-25 minutes. The flasks containing media were inoculated with three mycelial bits of 5mm diameter from 7 days old culture of P. grisea under aseptic conditions. Then the inoculated flasks were incubated at 25+ 2°C for 15 days. Three replications per medium were maintained. These flasks were regularly shaken after 3-4 days for the uniformspread of the fungus. After incubation period, 1 gm of sample was taken from each flask and was added to 3 ml of sterilized water in the test tubes and was shaken well. The number of conidia/ml present in each suspension were calculated with the help ofhaemocytometer. The results presented in Table 1 revealed that the number of spores/ml produced by all the substrates ranged between 0.33xl06/ml to 5.6xl06/ml.
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