Formation of onion bulblets in vitro and viability during medium-term storage

The influences of light conditions, sucrose and ethylene on in vitro format ion and storability of onion (Allium cepa L.) bulblets were studied in vari ous accessions. Light, sucrose and ethylene influenced bulb formation. Stor ability was primarily enhanced by a high sucrose concentration (100 g/l) in the culture medium. The bulbing process was characterised by changes in bu lbing ratio, leaf length, number of leaves and leaf development time. The v iability of bulbs after 1 year of in vitro storage at low temperatures was determined by their growth reaction in subsequent subcultures, growth after transfer into the greenhouse and tetrazolium staining. Sufficient sproutin g of bulblets previously stored at -1 degreesC demonstrated the possibility of storing them in a low-temperature, slow-growth culture.