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PHYTOCHEMICAL AND ANTIMICROBIAL EFFECTS OF METHANOLIC EXTRACTS OF AFRAMOMUM MELEGUETA (SCHUMANN) AND ZINGIBER OFFICINALE (ROSCOE) ON FUNGAL ISOLATES OF TOMATO FRUIT (LYCOPERSICON ESCULENTUM

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Abstract

Tomato (Lycopersicon esculentum L.) fruits of Roma variety obtained from Nsukka in Nsukka Local Government Area of Enugu State were investigated for the cause of rot found in them. Four fungal pathogens were isolated and identified namely Helminthosporium solani (Durieu and Mont), Aspergillus niger (Tiegh), Penicillium digitatum (Pers) Sacc. and Mucor piriformis (Fisher). These pathogens were responsible for the post harvest rot of tomato in Nsukka, as proved by the pathogenicity tests. A. niger was the most virulent of the four pathogens. Growth of these pathogens was controlled using methanolic extracts of Aframomum melegueta seeds and rhizomes of Zingiber officinale. Phytochemical analysis of the extracts revealed the presence of tannins, phlobatannin, steroids, tarpenes, saponins, flavonoid and alkaloid compounds. These extracts were found to be fungitoxic on all tested pathogens when used to control their growth in vitro. The effects of these extracts on the radial growth of the pathogens were highly significant (P < 0.05) for all treatments. Z. officinale extract at 25% concentration completely inhibited all the pathogens. A. melegueta extract at 25% inhibited H. solani and M. piriformis completely, and reduced P. digitatum by 92.99% and A. niger by 89.09%. Both extracts inhibited the pathogens completely at 30% concentration. The degree of reduction in growth of these pathogens by methanolic extracts of A. melegueta and Z. officinale varied and was highly significant at (P < 0.05).