Abstract: The effect on the ultrasturcture of mesophyll cells and correlation among the ultrastructural changes, protective enzyme activities, destraction of membrane peroxidation was studied with the leaves of hybrid maize (Zea mays L. ) during water stress induced by hypertonic solution (PEG, 1500). During initial period of water stress, the ultrastructural changes of mesophyll cells were unremarkable, SOD and catalase (CAT) activities increased obviously. The permeability of plasma membrane and malondialdehyde (MDA) content increased slowly with the extension of water stress, ultrastructural injury of mesophyll cells was serious, and the sensitivity of organelles to water stress was much different, SOD and CAT activities decreased, the permeability of plasma membrane and MDA content increased rapidly. Moreover, the ultrastructure of mesophyll cells. SOD and CAT activities, the permeability of plasma membrane and MDA content could be partly recovered after rewatering. There were great differences between maize hybrid and it’s parental inbred lines during water stress and rewatering.

Key words: Water stress: Maize, Ultrastructure, Protective enzyme, Lipid, Peroxi Dation