Onion is one of the main commodities in Morocco. However, several types of losses may occur at postharvest. Our objective is to study the situation of this post-harvest sector and to identify the causes and constraints encountered during the sale and consumption of this product in Khémisset. The survey of certain stakeholders allowed us to determine the types and extent of losses. The damage observed is caused mainly by mechanical and pathological factors. We identified two phytopathogenic fungi, Fusarium sp and Aspergilus niger. In addition, we found that average losses were of about 17% among wholesalers, 15% among traders and 27% among households.

Keywords: Postharvest losses, onion, phytopathogenic fungi