Seed-borne fungi associated with farmer saved rice seed in Uganda and their effect on germination

Abstract

Seventy seed samples from three districts of Uganda, namely, Bugiri, Pallisa, and Lira were examined by the blotter method for fungal infection at Makerere University. Twenty different seed-borne fungi were identified and their incidence and infection levels varied significantly (P<0.01) with respect to location and within districts. Bipolaris oryzae was the most prevalent pathogen with an infection range of 3-94%. Phoma oryzae, Pyricularia oryzae, Alternaria padwickii, Fusarium moniliforme, Curvularia lunnata, Nigrospora oryzae, Verticilium cinabarium and Alternaria alternata were also present in all the districts. However, some pathogens were localised. For example, Exserohilum rostratum, and Curvularia eragrostidis were only encountered in Lira and Bugiri districts, respectively. Pallisa district had the least number of fungal species while Bugiri registered the greatest diversity. Mean infections were also low in Pallisa as opposed to Bugiri and Lira districts.

Nine categories of seedling abnormality were recorded. Seedlings with shoot and root decay were encountered frequently. B. oryzae, Phoma oryzae, Pyricularia oryzae, A. padwickii, F. moniliforme, C. lunnata, Melanospora zaminae and Alternaria alternata were found associated with 100%, 55.6%, 44.4%, 66.7%, 77.8%, 11.1% and 11.1% of the different abnormalities, respectively. Results of the present study have revealed the occurrence of a wide range of pathogenic fungi and their association with seedling abnormalities.