Aging of Winter wheat flag leaves and oxygen metabolism under nitrogen provision.

【Objective】The study was to promulgate the aging changes of Winter wheat flag leaves and oxygen metabolism under nitrogen provision.【Method】The experiment investigated the chlorophyll contents,photosynthetic rates,MDA content,SOD and POD activities and solvable protein content in the flag leaves of winter wheat at different rates of nitrogen provision(0,138,276 and 345 kg/hm2).【Result】Each time after flowering,the chlorophyll contents of the flag leaf were the highest,leaf senescence was postponed,metabolism intensity reduced slowly and the peroxidation degree was low when the amount of the nitrogen-provision was 276 kg/hm2.The chlorophyll content and the senile target and so on were not as good as the treatments in which the nitrogen-provision was 0,138,345 kg/hm2.【Conclusion】Right amount of nitrogen provision(276 kg/hm2) raises the chlorophyll content,the soluble protein content,the SOD and CAT activities,reduces the peroxidation degree of the membrane fat,and over nitrogen-provision(345 kg/hm2) promotes the leaf senescence of winter wheat.