Abstract:

Calycanthus chinensis is an endangered species which has survived from the tertiary period, and now it is only distributed in Zhejiang Province of China. In order to provide a scientific basis for conservation and cultivation of the plant, the effects of soil drought stress on antioxidant system and lipid peroxidation in leaves were investigated using 2-year-old pot-cultured seedlings. Fifteen pots of the seedlings with a similar growth rate were subjected to different levels of drought stress (no stress, mild stress, moderate stress, severe stress and extremely severe stress). In comparison with no stress and mild stress, antioxidant ability in leaves of C. chinensis significantly increased, while lipid peroxidation remained steadily under moderate stress. Proline content, superoxide dismutase (SOD) and peroxidase (POD) activities significantly increased, while the content of glutathione (GSH), ascorbic acid and carotenoid and catalase (CAT) activity significantly decreased under severe stress. As a result of increase in generating rate of superoxide anion (O₂^-· ) and content of hydrogen peroxide (H₂O₂), membrane permeability of leaf cells and malondialdehyde (MDA) content increased, while net photosynthetic rate (P_n), maximal photochemistry efficiency (F_v/F_m) and apparent quantum yield (AQY) decreased to different extents. The present conclusion is that C. chinensis growth could be inhibited by enhancing lipid peroxidation under severe and extremely severe drought stress.

Key words: Calycanthus chinensis, drought stress, lipid peroxidation, defense enzyme