Determination of ideal culture media for optimal mycelia growth of rice blast pathogen(Magnoporthe oryzae)

Abstract

The study was carried out to evaluate the optimal culture medium for mycelia growth of strains ofrice blast pathogen (Magnaportheoryzae) in the laboratory. The blast infested leaves, stem and panicle collected from farmers’ field in three Local Government Areas (Gbako, Katcha and Lavun LGAs) of Niger State, Nigeria. Samples were cultured using Potato Dextrose Agar (PDA). The incubation was done at ambient temperature of 28+2 0C and the associated fungi were identified. Pathogenicity test was done in the screen house to authenticate the causative organism of rice blast. Growth rate of M. oryzae was then assessed in four different media namely: Potato Dextrose Agar (PDA), Potato Carrot Agar (PCA), Malt Extract Agar (MEA) and Rice Agar (RA). A total of ten strains of M. oryzae were isolated and given hypothetical names MOR01 to MOR10. The result of pathogenicity test confirmed the isolates to be causative organism of the rice blast. All the media test supported the growth of M. oryzae. However, at the end of the evaluation, MOR10 showed more affinity for PDA with highest mycelia radial growth of 80mm in diameter. MOR07 had the least mycelia radial growth of 70mm. In PCA, MOR09 had the highest mycelia radial growth of 70mm, while the radial growth of MOR03, MOR05 and MOR06 were the highest (65mm each) in MEA. Therefore, for the optimal production of M. oryzae, PDA followed by PCA are the recommended optimal culture media.