Onion (Allium cepa L.), cultivars, production, storage

The production of onions, worldwide and in Switzerland ranks at the forth position of all vegetable produced. In Europe cultivars are mainly available from breeders from France, Netherlands, Germany and Japan. Onions are of high nutrional value. The development of onion leaves is highly correlated to the sum of daily maxima Temperatures, independent of the site of production. In contrast the development of the onion, its yield potential and size depends on the cultivar, spacing and production system. Following quality regulations three main gradings of onions are distinguished: onions for sauces (22-35 mm Ø), sales at groceries (35-70 mm Ø) and for industry (>70 mm Ø). Onions, harvested in late summer, can easily be stored in barns up to six months. For the integrated production (IP) onions are mainly produced by direct sowing, where as for organic farming (BIO) mainly sets are used. As an alternative to sets, transplants are used as well. Results are shown from different trials comparing the different production systems