Onion culture (Allium cepa L.) is very important among vegetables grown in Brazil. In terms of production it is only overcome by tomatoes and potatos and in somes regions of São Paulo, Pernambuco, Rio Grande do Sul and Santa Catarina it is the main economic activity. The objetive was the characterization of some morphological and physiological aspects of onion that change with climate conditions. A satisfactory knowledge about onion exist, however there is a need for constant improvement in technology to improve production and normalize supply.
onion; morphological; physiological; production
