Fungi Associated with the Deterioration of Post-harvest Onion Bulbs Sold in Some Markets in Awka, Nigeria

Abstract

Onion bulbs rots are caused by microorganisms especially fungi leading to economic loss. These fungi have been known to produce toxins which are injurious to human and animal health, therefore in this study, the fungi associated with the spoilage of onions bulbs purchased from Umuike, Amaikwo, Amaudo, Okpuno and Permanent site markets were isolated, characterized and identified. The average fungal counts ranged between 1.2 x 103 CfU/ml and 2.0 x 103 CfU/ml. The fungi isolated from the spoilt onion bulbs were Penicillum digitatum, Fusarium oxysporum, Rhizopus stolonifer, Alternaria alternata, Aspergillus niger and Saccharomyces cerevisiae. The samples from Amaudo market had the highest percentage distribution of fungi of 34.2% while those from permanent site had the least percentage distribution of 8.6%. Aspergillus niger had the highest percentage distribution of 34.29% in the spoilt onion bulbs while Saccharomyces cerevisiae had the least percentage distribution of 5.71%. Aspergillus niger also had the highest rot diameter of 40mm while Saccharomyces cerevisiae had the least rot diameter of 16mm. Adequate mycological knowledge, storage facilities and handling practices would therefore minimize the deterioration of onion bulbs thereby ensuring its availability to the society all year round.