Abstract: Under low temperature stress , as a product of membrane liquid peroxidation , malondialdehyde (MDA) content in leaves of Butia capitata seedling gradually increased with elongation of stress time and stress intensity. Membrane lipid peroxidation raised more quickly under - 8 ℃than that under 2 ℃. As for membrane permeability , there was only a little change under 2 ℃, but it showed a sharp increase under - 8 ℃, indicating that cell membrane suffered severe damage after 24 h of - 8 ℃. Cell defense enzymes SOD , POD and CAT activity raised immediately in 6 h and then decreased under - 8 ℃. They were severely inhibited by low temperature stress. Under 2 ℃, SOD activity had little change in 6 h , and then decreased. CAT activity had a similar trend with that under - 8 ℃, but it changed by a lower ranger. Though POD activity also took a trend of increasing firstly and then decreasing , POD activity maintained a high level until 48 h , it gave us a hint that 2 ℃ low temperature stress probably could not inhibit , but promote POD activity in 48 h for leaves of Butia capitata
seedling.

Key words: Butia capitata Becc seedling, Low temperature stress, Membrane lipid peroxidation, Cell defense enzyme