Thesis Abstract

The fungitoxic properties of ethanolic and aqueous leaf extracts of Azadirachta indica and Ocimum gratissimum used for the control of post-harvest fungal diseases of Solanum melongena were tested in vitro with benlate serving as the standard fungicide and water as the bank control. Three fungal species, Aspergillus niger, Rhizoctonia solani and Mucor ramosissimus were isolated from diseased S. melongena fruits kept at room temperature on laboratory tops for10 days. The fruits started showing signs of decay after 4 days of exposure. Growth on the fruits at the sites of the rot suggested the presence of fungal pathogens. Isolation and culturing of these pathogens gave the identified species as the causal agents. Pathogenicity test confirmed them as the causal organisms of the fruit rot. The three pathogens were treated with both ethanol and aqueous leaf extracts of the two plants at concentrations ranging from 25 to 100% and benlate at concentrations between 2.5 and 10.0%. Various concentrations of the extracts were added to prepared Potato Dextrose Agar (PDA) media. The pathogens were inoculated separately into the PDA media and were incubated for eight days. Fungitoxic effects of these extracts on the mycelial growth of the pathogens were significant at P ≤ 0.05 for all treatments. The three pathogens were completely inhibited by the two plant rextracts for both the aqueous and ethanolic extracts at 100% concentration. With respect to ethanolic extract, O. gratissimum was more efficient than A indica, but the reverse was the case with aqueous extracts. Ethanolic extracts were generally more effective than the aqueous extracts. Ethanolic leaf extract of O. gratissimum may be used to effectively control post-harvest fungal diseases of S. melongena.

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