<i>In-Vitro</i> Study of Biofungicidal Effects of <i>Cassia alata</i> Leaf Extracts on Some Pathogenic Organisms of White Yam (<i>Dioscorea rotundata</i>) Tuber in Storage

Abstract

A preliminary experiment was conducted to evaluate the efficacy of Cassia alata leaf extract as a biofungicide and also to determine the minimum inhibition concentration (MIC) of the extract on organisms that cause soft rot of yam tuber in storage. The study was done at the plant pathology laboratory of University of Nigeria, Nsukka. The fungal organisms were isolated from the decaying yam tuber obtained from the yam storage barn of the Department of Crop Science, University of Nigeria, Nsukka. The Cassia alata leaf was obtained from the Botanical garden of the Department of Botany, University of Nigeria, Nsukka and ethanolic extraction was got using cold extraction method. The extract was further diluted to four levels of concentration thus: 250, 175, 87.5 and 48.75 mg/ml. The sensitivity pattern of the isolated fungal organisms was carried out using Agar cup diffusion technique. Organisms found sensitive to the extract were Scopulariopsis brevicaulis and Rhodorula mucilaginesa but Penicillium restrictum and Penicillium digitalum were not. Result of the sensitivity test showed that the extract was able to inhibit the growth of R. mucilaginesa at 56.23 mg/ml while the MIC of the extract for S. brevicaulis was 50.10 mg/ml. A major finding in this study is that the ethanol leaf extract of C. alata is selective in its bioactivity on the rot-causing organisms of yam.Keywords: In-Vitro, Biofungicidal effects, Cassia alata extracts, Pathogenic organisms, Dioscorea rotundata