Leaf senescence and photosynthesis in foxtail millet [Setaria italica (L.) P. Beauv] varieties exposed to drought conditions.

In this paper, we studied the changes of net photosynthetic rates (Pn), the contents of chlorophyll, soluble protein, malondialdehyde (MDA), superoxide radical (O2 ), and hydrogen peroxide (H2O2), and the activities of superoxide dismutase (SOD; EC1.15.1.1) and catalase (CAT; EC 1.11.1.6) in the leaves of two foxtail millet varieties (05-61 and Jingu3) under drought stress from 14 days after anthesis to maturity. PN, the contents of chlorophyll and soluble protein and the activities of SOD and CAT increased and then declined as the plants aged, whereas the accumulation of MDA, O2 - and H2O2 gradually increased with senescence. Although the leaves of two varieties generally shared a similar pattern of senescence, their rates of aging differed. The activities of SOD and CAT in leaves of 05-61 declined more quickly than Jingu3, particularly in the late stages of grain filling. Taken together, the results implicated that the alleviation of leaf senescence played an important role in promoting grain filling and enhancing the yield and quality of 05-61 in the rain-fed agriculture area.