Title : Characterization of rot-causing fungi associated with post-harvest deterioration of yam tubers during storage in Calabar, Nigeria
Abstract:
Post-harvest deterioration of yam by microorganisms is a major constraint militating against yam production and marketing in many yam-producing countries. This study aimed to identify the fungal pathogens causing rots and their impact during the storage of yam tubers in Calabar. Twenty yam tubers were collected from a warehouse at Akim market in Calabar and kept to rot. Eighteen of the tubers developed different symptoms of dry, wet and soft rots during storage from which 15 fungal pathogens were isolated. The pathogens were isolated; and characterized based on identified morphological characteristics, in addition to molecular data. The main fungi isolated were Aspergillus spp., Lasiodiplodia spp. and Rhizopus spp. Nucleotide sequence identities ranging from 60.0 to 97.6% were obtained among the isolates indicating various degrees of affinity. Pathogenicity test on D. rotundata and D. alata showed that all the isolates displayed typical symptoms of different yam rots as were observed in the original rotted yams from which the pathogens were isolated among the fungi isolates, Rhizopus spp. was the most invasive causing up to 100% rot of the tubers. Based on the present study data, it is recommended that in addition to employing improved methods of handling and storing yam tubers, developing resistant varieties will effectively cut down on postharvest losses caused by biological agents.
Key Words: Dioscorea spp.; Fungal disease; Phylogeny; Rots; Yam
