Physiological and biochemical responses of six herbaceous peony cultivars to cold stress

Although herbaceous peony cultivars have been introduced and promoted widely, a key limitation to their use is their level of cold hardiness. In this study, the physiological and biochemical responses of six herbaceous peony cultivars to different temperatures and periods of exposure to freezing temperatures were assessed by analyzing changes in six indices. Under our experimental conditions, relative electric conductivity, soluble sugar concentration, soluble protein concentration, and malondialdehyde concentration generally increased as temperature declined, while proline content decreased. Superoxide dismutase activity fluctuated. After the same indicators were used to assess cold resistance over time at -20 degrees C, the six cultivars could be ranked, in decreasing levels of cold resistance, as: 'Da Fu Gui', 'Fen Yu Nu', 'Kansas', 'Monsieur Jules Elie', 'Taff, and 'Pink Hawaiian Coral'. (C) 2014 SAAB. Published by Elsevier B.V. All rights reserved.