Onion crop (Allium fistulosum L.) has found an important niche in Colombian agriculture, with few studies of mycorrhizal symbiosis in productive zones. The objective of this study was to identify Arbuscular Mycorrhizal Fungi (AMF) and their relationship with agroecological zones in the onion production system. In the department of Antioquia, 23 rhizosphere soil samples were collected in lots with established onion crops for the determination of AMF, and GIS layers of the agroecological zones were applied to superimpose them. A total of 34 AMF morphospecies represented in the families Glomeraceae, Claroideoglomeraceae, Acaulosporaceae, Gigasporaceae, Ambisporaceae and Paraglomeraceae were found. The highest AMF importance value was presented by Glomus trufemii, followed by Glomus tenerum, Claroideoglomus etunicatum, Glomus microcarpum and Glomus warcupii. High affinity of the AMF Glomus s...