The Effect of Melanthera Scandens and Mimosa Pudica on Fungi Causing Postharvest Deterioration of Cassava Root Tubers

Abstract

Fresh cassava (<i>Manihot esculenta</i>) tubers unlike most other tubers of root crops are highly perishable. This study, therefore, investigated the antifungal activities of ethanol and hot water extract of <i>Melanthera scandens</i> (vine) and <i>Mimosa pudica</i> (touch me not) on rot fungi of cassava. Rotten cassava tuber samples were inoculated into Potato Dextrose Agar (PDA) for isolation of rot fungi causing postharvest deterioration of cassava tubers. The fungi obtained were identified using macroscopic and microscopic characteristics. The establishment of the pathogenicity of the fungal isolates was carried out by inoculating freshly harvested cassava tubers with the isolated fungi. The ethanol and hot water extract of the selected plants were tested against the isolated fungi both <i>in vitro and in vivo</i>. The isolates were identified as <i>Aspergillus niger, Aspergillus flavus, Penicillium notatum, Penicillium sp, and Fusarium verticillioides. A. flavus</i> being the most virulent with a percentage in severity of (27.15) on day 7 as compared with <i>Aspergillus niger, Fusarium verticillioides, Penicillium sp, and Penicillium notatum</i> which had (25.22, 17.17, 15.76 and 14.71) respectively. In the <i>in vitro</i> test the plants exhibited a high degree of fungicidal activity by inhibiting the mycelia growth of the rot fungi and <i>Mimosa pudica</i> was more effective in the suppression of fungal growth than <i>Melanthera scandens</i>. In the <i>in vivo</i> test there was a higher percentage reduction in diameter of rot when the plant extract was applied after twenty four hours of microbial inoculation directly to the cassava tuber. The extracts of <i>Melanthera scandens</i> and <i>Mimosa pudica</i> can therefore be used as a bio fungicide to extend the shelf-life of freshly harvested cassava tubers.