Abstract:

The physiological responses and their correlations of Populus hopeiensis leaves during PEG osmotic stress were investigated in this paper. The results showed that under the osmotic stress of PEG solution，the relative water content decreased，the content of malondialdehyde (MDA) increased and cell membrane selective permeability was deteriorated during the process of stress. After 24 h of stress，the O₂ production rate increased while the activities of superoxide dismutase (SOD) and peroxidase (POD) decreased. However，the activities of SOD and POD，the content of proline and soluble sugar increased at 18 h of treatment with the PEG solution，which might alleviate the damage of the stress. Correlation analyses showed that there was a significant negative correlation between the relative water content and MDA content or O₂ production rate respectively，whereas there was no significant correlation between the relative water content and the activities of SOD and POD. SOD activities were significantly and negatively correlated with O₂ production rate while no significant correlation was found between the relative water content and POD activities. The relationship between the above physiological indexes indicated that the responses of Populus hopeiensis leaves during PEG osmotic stress were the results of various physiological processes，and there existed some close correlations among the indexes in some way.

Key words: Populus hopeiensis, PEG, osmotic stress, physiological responses, correlation analysis