Leaf senescence and protective enzyme system of broomcorn millet under drought condition

In three broomcorn millet varieties of Ningmi 13,Neimi 5 and Jinmi 4 which were planted in arid shed,chlorophyll contents,SOD,CAT,POD activities and MDA contents were analyzed after flowering under drought.The results showed that the chlorophyll contents,SOD,CAT and POD activities decreased gradually from 14 days after the varieties flowered,but MDA contents increased gradually as leaves senescence went on.Although the leaves of the varieties presented a similar tendency in their senescence,their senescence progresses differed significantly.Compared with Neimi 5 and Jinmi 4,the leaves of Ningmi 13 declined slowly in chlorophyll contents,SOD,and CAT activities,declined fast in POD activity,and increased slowly in MDA content,thus prolonging their function duration and slowing down the senescence of its leaves,which is conductive to the accumulation of photosynthate;Chlorophyll content,SOD and CAT activities had the positive correlation with yield per plant,but POD and MDA content had negative correlation with yield per plant under drought condition.