Viability loss and oxidative stress in lily bulbs during long-term cold storage

The regeneration ability of bulb scales of the Asiatic hybrid lily (Lilium hybrids L.) 'Enchantment' was monitored for bulbs stored for 0 to 5 years at - 2 degrees C in moist peat. Regeneration ability decreased after more than 1 year of storage and was completely lost after 5 years. Possible involvement of oxidative stress in the loss of regeneration capacity was tested. In this study we used white (i.e. with no visual damage) scales to test whether breakdown of membranes by oxidative stress was an early event in this storage-induced viability loss of lily bulbs. The content of reduced glutathione, which was the main nonprotein thiol in the bulb scales, remained nearly constant, while that of oxidized glutathione was slightly increased after 3.3 years of storage. Significant changes in the content of phospholipids, neutral lipids and free fatty acids were not detected during storage. The degree of unsaturation of fatty acids in phospholipids increased during the first 3 years of storage. Ion leakage of bulb scales was not increased in bulbs that were stored for less than 4 years. No indication was found that oxidative stress is a major factor associated with the loss of regeneration capacity of lily bulbs during cold storage. (C) 1997 Elsevier Science Ireland Ltd.