Changes in Some Enzyme Activities of Peanut Leaves During Leaf Senescence

The changes in activity of some enzymes in peanut leaves during leaf senescence were studied with two high yielding peanut cultivars (cv. Luhua 11 and Fu 8707) in the campus and experimental farm of Shandong Agricultural University, Taian, China. The main results were as follows. Through the whole process of leaf growth and senescence, changes in activities of superoxide dismutase (SOD),catalase(CAT),peroxidase(POD) and nitrate reductase(NR) in leaves, can be fitted to a parabolic function, Y = A + BX + CX 2, where Y refers to the values of above parameters and X to the days after leaf unfolding(Table 1). Content of malondialdehyde (MDA) and production of superoxide radicle(O -· 2)in leaves changed from slow ascent after unfolding into fast ascent in late phase of senescence(Figs. 2,3). These tendencies of change could be described by an exponential function of Y = A e Bx ,where Y refers to the values of above parameters and X to days after leaf unfolding. The increase in O -· 2and MDA accumulation ,and the decrease in SOD,POD,CAT and NR activities in leaves were the main causes for leaf senescing.