Senescence is considered to associated with reactive oxygen
species (ROS), such as superoxide (O2
•−) and singlet oxygen. The
defense system, which included antioxidant enzymes and antioxidants,
play an important role in the oxyradical detoxification
process (Han et al., 2006; Mittler, 2002). It is well known that
POD and SOD are important oxyradical detoxification enzymes in
plant tissue, thus these enzymes were assayed in our study. SOD
can catalyze O2