Effects of Plant Density and Nitrogen Fertilizer on Physiological Characteristics of Flag Leaf of Weak-and Medium-gluten Wheat at Late Growth Stage

The experiment was conducted to study the effects of plant density and nitrogen fertilizer on the physiological characteristics of flag leaf in weak gluten wheat Yangmai 9 and medium gluten wheat Yangmai 11 at late growth stage.The results indicated that the SOD and POD activities and chlorophyll content showed a trend of decreasing,while the MDA content showed a trend of increasing at late growth stage.Under the experimental condition,240 kg/hm2 N with the ratio of basic∶tillering∶elongation and booting fertilizer as 5∶1∶4 could postpone the plant senescence,prolong the grain-filling time,increase the photosynthetic ability of flag leaf and protein content in grains of Yangmai 11 with 120×104 basic seedlings per hectare,so good quality and high yield could be obtained.But for Yangmai 9 with 240×104 basic seedlings per hectare,180 kg/hm2 N with the ratio of basic∶tillering∶elongation and booting fertilizer as 5∶1∶4 was the best for coordinating the contradiction between high yield and good quality,which could guarantee the quality reach the standard and increase the SOD and POD activities,chlorophyll content and the photosynthetic ability of flag leaf,but decrease MDA content and delay the plant senescence.