Changes of Chlorophyll and Enzyme Activity in Active Oxygen Scavenging System of High-yielding Wheat Variety Jimai 22

To make clear the physiological basis for high yield in winter wheat Jimai 22,the variation of the content of chlorophyll and MDA and the activity of SOD and POD in active oxygen scavenging system of flag leaf were studied during the process of natural senescence.The chlorophyll content kept higher level all along,and the slowly decreasing stage was prolonged,so the functional period of flag leaf was prolonged and the plant senescence was postponed relatively,which led to the increase of grain weight.The SOD and POD activity were discovered with higher level,especially in the dough stage(24 days after anthesis),so the free radicals of active oxygen could be scavenged effectively and the leaves were protected from the damage.The MDA content was lower and increased slightly,so the membrane lipid peroxidation was weaker.All these indicated that the strong scavenging ability existed in the enzyme defense system in flag leaf of Jimai 22,and the membrane lipid peroxidation could be inhibited effectively,correspondingly,the functional period of flag leaf was prolonged and the plant senescence was postponed.In wheat breeding,the important measure to achieve the breakthrough in yield was to screen stay-green variety.