Etiology of Grain Discolouring Mycoflora of Rice

The sample collected during the survey showed maximum frequency (35%) of Curvularia followed by Alternaria (20%) and others viz., Fusarium, Aspergillus, Penicillium, Heliminthosporium, Pyricularia arid Rhizopus spp. The fungi isolated from discoloured rice grains were Curvularia lunata, Alternaria alternata, Fusarium maniliformae, Heliminthosporium oryzae and Pyricularia grisea. Artificial inoculation of these mycoflora showed clear infection at 85–90 days and the mycoflora colonization on grains gave black, black dots, dark brown, ash gray and light to dark brown spots respectively on the ear head. Aspergillus, Penicilium and Rhizopus were not pathogenic in any stage of the crop as there was no symptom on panicle and seed discolouration. The infections of C. lunata, A. alternata were detected from seed coat and endosperm where as fungi like P. grisea, F. moniliformae were detected from all parts of seed viz., seed coat, endosperm and embryo.