The Evolution of Physiological Characteristics of Maize Root during Varietal Replace in China, 1950s to 1990s II.Changes of the Protective Enzyme Activities and Lipid Peroxidation

The study was conducted in combining the field cultivation and limited soil cylinder cultivation, for comparisons of the commercial maize varieties planted in 1950s to 1990s in China to analysis the changes of root antioxidant enzymes activity. The result indicated that activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase(POD) activities increased, while malondialdehyde (MDA) content declined as the replacement of maize varieties continued in China. The process of the new variety released was gone together with the ability improvement against active oxygen in root and root senescence. This tendency was more obvious at later growth stage. For maize varieties of 1990 s, the root in deep soil showed higher activities of these protective enzymes and lower content of MDA than that of 1970 s and 1950 s varieties. These characteristics might be helpful for the maintenance of root physiological activity during the grain filling period for varieties of 1990 s.