追施氮肥对灌浆期沙地饲用燕麦叶片衰老特性的影响

Effects of Applying Nitrogen Fertilizer on Leaf Senescence Characteristics of Oat in Sandy Land during Grain Filling Stage

为探究氮素对饲用燕麦叶片衰老特性的影响,在科尔沁沙地,以燕麦为材料,于苗期、分蘖期、拔节期、抽穗期按照15%,40%,25%,20%比例,对燕麦追施0(CK),70,140,210,280 kg/hm^2纯氮,检测灌浆期燕麦叶片的叶面积、叶绿素含量、可溶性蛋白含量、抗氧化酶活性及膜脂过氧化程度。结果表明:追施氮肥对延缓叶片衰老、提高功能叶作用时间和效率有明显作用。在一定范围内随着施氮量的增加,饲用燕麦的叶面积、叶绿素含量均显著提高,可溶性蛋白含量增加,而MDA含量明显降低,SOD活性显著下降,POD活性和CAT活性显著增强,延缓叶片的衰老进程。当施氮量超过210 kg/hm^2后,继续增施氮肥旗叶叶面积、叶绿素含量及可溶性蛋白含量均明显下降,且不能持续提高花后叶片POD和CAT活性,但SOD活性显著增强,MDA含量显著升高。试验亦表明,清除植物体内氧自由基并非单一的酶作用结果,取决于SOD、POD、CAT保护酶系协同作用,在科尔沁沙地追施210 kg/hm^2氮肥,饲用燕麦叶片抗衰老能力最强。

To explore the effect of nitrogen on senescence characteristics of fodder oat leaves,in Horqin sandy land,using oat as material,pure nitrogen of 0( CK),70,140,210,280 kg/ha was applied to oats at seedling stage,tillering stage,jointing stage and heading stage in proportion of 15%,40%,25% and 20%. Leaf area,chlorophyll content,soluble protein content,antioxidant enzyme activity and membrane peroxidation degree were measured. The results showed that the application of nitrogen fertilizer had an obvious effect on delaying leaf senescence and improving functional leaf time and efficiency. In a certain range with the increased of nitrogen,chlorophyll content,leaf area of oat were significantly improved,the soluble protein content increased,while MDA content decreased,SOD activity decreased significantly,POD activity and CAT activity were significantly enhanced,delaying leaf senescence. When the nitrogen was more than 210 kg/ha,continuing to increase nitrogen application,flag leaf area and chlorophyll content and soluble protein content decreased significantly,and could not improve leaf POD and CAT activity after flowering,but the activity of SOD was significantly increased;MDA content increased significantly. This experiment also indicated that scavenging oxygen free radicals in plants was not a single enzyme action. It depended on the synergistic action of SOD,POD and CAT protective enzymes. The application of 210 kg/ha nitrogen fertilizer in the Horqin sandy land had the strongest anti-aging ability.