Activité antifongique d’extraits aqueux de Cymbopogon citratus (D.C.) Stapf., Eclipta alba (L.) Hassk. et Portulaca oleracea (L.) contre les principaux champignons transmis par les semences d’oignon (Allium cepa L.) au Burkina Faso

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Résumé

Aspergillus and Fusarium species are the major seed-borne fungi occurring on onion in Burkina Faso according to
a previous study. In order to work out effective, available and healthy method of seed treatment against these fungi, this
study aimed to evaluate the antifungal activity of three local botanical species. Mycelial growth of Aspergillus niger, Fusarium
moniliforme, Fusarium oxysporum and Fusarium solani was evaluated in vitro on media prepared with aqueous extracts of
Cymbopogon citratus, Eclipta alba and Portulaca oleracea. The health and germination quality of seeds previously treated
with the best aqueous extracts were then evaluated. The aqueous extract of C. citratus significantly inhibited the mycelial
growth of all Fusarium species at rates ranged from 42,8 to 92,0% but stimulated the growth of A. niger. Those of P. oleracea
inhibited the mycelial growth of all tested fungi at rates ranged from 3,2 to 42,4% while those of E. alba stimulated the
mycelial growth of all tested fungi. Seed treatment with the extracts of C. citratus and P. oleracea allowed reducing their
infection rates by fungi of over 50%. However, the emergence and growth of seedlings were respectively reduced by P.
oleracea and C. citratus compared to those of untreated seeds. Our study concludes that both aqueous extracts have proven
antifungal properties. The appropriated shape and dose of use, that does not affect the seedling emergence and growth,
should be sought.

Mots-clés

Antifungal activity, Aqueous extracts, Onion, Seed-borne fungi, Seed treatment.