EVALUATION OF ANTIFUNGAL ACTIVITY OF SOLANUM NIGRUM AGAINST ASPERGILLUS NIGER, THE CAUSE OF BLACK ROT DISEASE OF ONION

Abstract

Antifungal activity of methanolic leaf and root extracts of Solanum nigrum L. was tested against Aspergillus niger Teigh. that causes black rot disease of onion (Allium cepa L.). Different concentrations of methanol leaf and root extracts viz. 1%, 2%, 3%, 4% and 5% were applied in vitro against A. niger. Root extract was proved more antifungal than leaf extract as its 5% concentration reduced the test fungal growth by 30%. Methanol root extract of S. nigrum was selected for further fractionation and this was partitioned by using various organic solvents viz. n-hexane, chloroform, ethyl acetate and n-butanol. MIC (minimum inhibitory concentration) of the isolated fractions along with a commercial fungicide (metalaxyl+mancozeb) was checked by serial dilution method against A. niger. Various concentrations (0.20 mg mL^-1 to 0.0007 mg mL^-1) were used for MIC bioassay and data was recorded after 24, 48 and 72 h incubation period. Chloroform fraction and synthetic fungicide more effectively retarded spore germination of A. niger with MIC 0.0007 mg mL^-1. The other fractions were comparatively less antifungal and their order of effectiveness was ethyl acetate > n-hexane>n-butanol.