Abstract: This research aims to study maize leaves activity and the senescence characteristics of oxygen metabo-lism and it regulation by using Zhengdan 958 and Yudan 2002. The results showed that SOD，CAT activi ties of differ-entleaves rose and then declined with plant senescence，but MDA contents gradually increased as leaves senescencewent on. Although the leaves of the two varieties generally presented a similar tendency in their senescence，their se-nescence progresses significantly differed. Compared with leaves of Yudan 2002，the content of active oxygen protectiveenzyme and soluble protein of Zhengdan 958 were higher and declined more slowly and the content of MDA was lowerand rose more gradually. The activities of SOD and CAT of leaves increased in the seed dressing treatments which re-sulted in decreased MDA contents and soluble protein degradation rate of leaves. Results suggested that the treatmentsof maize seed dressing can prolong leaf life，effectively control or slow down the senescence，maintain physiolo gicalfunctions of its leaves during the growth and increase yield.

Key words: Maize leaf, Senescence, Defending enzyme activity, Plant growth regulator

CLC Number: 

• S513.01