Summary
A study was made of the behavior of onion (Allium cepa L.) cultivars, with short day characters, during two agricultural years in Manaus, AM. Among the characters evaluated those of transplant survival and unproductive plants influenced negatively the production of the cultivars. It was concluded that these characters are critical for the adaptation of the onion, and the cultivars Barreiro Roxa de Piracicaba. Roxa Chata and Baia do Cedo can contribute genetic variability in different degrees, to obtain onions adapted to the condictions of Manaus.