OCCURRENCE OF ASPERGILLUS SPECIES AND AFLATOXIN IN GROUNDNUT (ARACHIS HYPOGAEA L.) AND ANTIFUNGAL POTENTIALS OF PHYTOCHEMICALS IN EASTERN ETHIOPIA

Abstract

Groundnut (Arachis hypogaea L.) is one of the most important food and oil crop in Ethiopia. However, the production and productivity of the crop are constrained by various factors. Of which, pre-and post harvest mold infections are the major problems. Thus, the present study was undertaken with the objectives to determine Aspergillus species associated with groundnut in the farmers’ storage's in Eastern Hararghe, assess the antifungal potential of selected phytochemicals against Aspergillus species infecting groundnut, and evaluate fumigation potentials of effective phytochemicals against Aspergillus species infecting groundnut and total aflatoxin contamination under storage conditions. 90 Groundnut samples were collected from three (Babile, Gursum and Fedis districts) of eastern Hararghe during 2018/2019 cropping season. Aspergillus species were isolated using Aspergillis flavus and Aspergillis parasiticus Agar medium. Results showed that Aspergillus species isolated from groundnut samples in the three districts were Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger, Aspergillus fumigatus and Aspergillus ochracies. Groundnut sample collected from all districts were dominantly affected by A. flavus (54 and 51%) and A. niger (57%). Out of the 20 plant extracts evaluated, 13 of them showed some antifungal activity against Aspergilus flavus using paper disc method and tested in a completely randomized design with three replications. The highest radial growth inhibition of A. flavus was exhibited by ethanolic extracts of A. sativum (71%) and C. citratus (65%). Methanol extracts of A. sativum (83%), and Z. officinale (59%) were showed highest potent activity against radial growth of A. flavus. The highest inhibitions of spore germination were attained by ethanolic extracts of C. citratus (100%), and A. sativum (91%). Methanolic plant extracts of A. sativum, C. citratus, and Z. officinale had statistically significant (p<0.05) difference with untreated control in spore diameter of A. flavus. In this experiment, methanolic extracts of A. sativum (98%), A. graveolens (96%), C. citratus (96%) and V. amygdalina (98%) did not inhibit germination of groundnut seeds. Data analizedusing SAS. Methanol extract of A. sativum and C. citratus reduced aflatoxin production by 76.6-100.0% under storage conditions. In conclusion, promising antifungal activity exhibited by some of the plants extracts in the present study, the application of methanolic extracts of A. sativum and C. citrates can be used to reduce total aflatoxin contamination of groundnut in storage conditions.