Influence of moisture content and length of storage on mold invasion of paddy rice

The following fungal genera were observed in field samples: Trichoconiella, Curvularia, Fusarium, Nigrospora, Phoma, Sarocladiom, Alternaria, Cladosporium, Verticillium, Rhynchosporium, Helminthosporium, Aspergillus and Rhizophus. Trichoconiella, Curvularia and Fusarium were the predominant fungi associated with grains in all growth stages tested although there was a decrease in their prevalence upon the maturity of the plant. The relationship of moisture content and storage period to fungal population, seed germination, grain whiteness and translucency was also determined. Various fungal species predominated at different moisture conditions and storage periods. The fungi observed were Aspergillus flavus oryzae, A. glaucus, A. nidulans, A. candidus, A. versicolor, A. terreus, A. niber and unidentified species of Penicillium, Trichoconiella, Curvularia, Fusarium, Syncephalastrum, Verticillium, Cladosporium and Rhynchosporium. The predominant storage fungi were A. flavus-oryzae, A. glaucus, and A. candidus whereas the predominant field fungi were Trichoconiella sp., Curvularia sp. and Syncephalastrium sp. A decrease in the number of field fungi and an increase in the number of storage fungi with storage time was observed. Storage fungi from the wet and dry season samples were noted as early as five weeks after storage at moisture contents from 9.3 to 18.33%. The percentage germination of paddy remained high when stored at moisture contents of 9.3-14.0% but decreased with storage time at 14.5-18.3% moisture content. The percent germination of paddy reached a peak at 10-15 weeks of storage and gradually decreased during further storage. A significant negative correlation between percent germination and moisture content was observed. At 14.5-18.3% moisture content, the germination of stored paddy rice decreased with a marked increased of storage molds.