Fungi Associated with Deterioration of Onion Variety (Colour)

Abstract

The incidence of fungi associated with deterioration of three varieties of onion bulbs was investigated in Usmanu Danfodiyo University, Sokoto. The bulbs were purposively collected in sterile polyethene bags through random sampling from kasuwan daji in Sokoto and brought to Mycology Laboratory, Department of Biological Sciences for analysis. Samples were prepared using standard procedures for Isolation and Inoculation of fungal organisms. Isolates were identified based on Morphological and cultural identification using mycological atlas. Pathogenicity test was out carried out using standard procedures. The result obtained revealed the presence of Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus and Rhyzopus oryzae. R. oryzae had the highest percentage of occurrence (47.4%) in Red onion, A.niger and A. fumigatus had the highest occurrence (39.1%) in white onion, and in the purple onion A. niger and A. flavus had the highest percentage of occurrence with (42.8%). The pathogenicity test indicated that all the isolates were found to facilitate spoilage of the bulbs. R. oryzae was found to be more pronounced on white onion, A. niger was prominent in purple onion, A. flavus on red onion. Therefore, fungal spoilage of onion could be determined base on the type of fungal organisms and the type of onion variety. The study could help formers to detect the type of organisms that are responsible for spoilage on the different onion varieties thus, determine the appropriate type of pesticides to apply either in the field or on storage.