Pathogenicity study of some seed-borne fungi of onion (Allium cepa L.) from Burkina Faso

Abstract

Onion production in Burkina Faso faces to several constraints including diseases. Symptoms such as seedling damping-off are currently been observed. Most of the fungi responsible for onion diseases are seed-transmitted but in Burkina Faso, little information on onion seed quality were available. In a previous study, Aspergillus niger, Fusarium oxysporum and Fusarium solani were found to be the main fungi present on onion seeds but their responsibility in the development of seedlings damping-off has not been established. The overall aim of this study is to evaluate in vitro, the effect of these fungi on onion seed germination and coleoptile growth in order to establish this responsibility. Onion seeds were inoculated with mycelium suspension of the fungi concentrated at 13.3 g/ml and incubated for 6 days under appropriates conditions. All the tested fungal isolates had an inhibitory effect on onion seed germination at rates ranging from 31 to 60%. The Fusarium species were the most virulent. Coleoptile length was also reduced by the fungi, leading to significant growth time-lag at rates ranging from 34 to 100%. Aspergillus niger was the most virulent. In conclusion, Aspergillus niger, Fusarium oxysporum and Fusarium solani are responsible of seedling damping-off of onion in Burkina Faso.