Some Fungal Pathogens of Yam (Dioscorea Spp.) In Storage And The Effects Of Their Infection On The Nutrient Composition

Abstract

The study isolated and identified three fungal pathogens of yam (Dioscorea spp.) in storage and investigated the effects of their infection on the yam nutrient composition. The pathogens were Aspergillus niger Van Tiegh, Botryodiplodia theobromae Pat and Sclerotium rolfsii Sacc. Results showed that the nutrient contents of the two species of yam, D. rotundata Poir. And D. alata L. were quantitatively altered by A. niger, B. theobromae and S. rolfsii during pathogenesis. The moisture content of both species significantly (P < 0.05) increased, whereas carbohydrate content significantly (P < 0.05) decreased in quantity during the period of incubation. The total protein and fat contents of both species were also lowered quantitatively, while the fibre and ash contents were increased by the rot causing organisms. The depletion of carbohydrate, protein and fat contents was more in D. rotundata than in D. alata. The results obtained suggests that the presence of carbohydrate, protein and fat is of primary importance for the survival and successful establishment of the pathogens within the tissue of yam.

Keywords: Fungal pathogen, nutrient composition, Dioscorea rotundata Dioscorea alata.