不同施氮水平对羊草抗衰老能力的影响

Effects of applying nitrogen fertilizer on leaf senescence characteristics of Leymus chinensis in sandy land

对人工建植的羊草草地施不同水平N(0、100、200、300、400 kg/hm^2分别用N0、N1、N2、N3、N4表示)肥,测定不同N素水平下羊草叶片的抗氧化酶活性、MDA含量及叶绿素含量分析不同施氮水平对沙地羊草衰老的影响。结果表明:施N可显著提高第1茬沙地羊草叶片中SOD,POD和CAT活性。随施N水平的增加,羊草旗叶、倒二叶和倒三叶叶片中叶绿素含量均呈先增加后减小的变化,下部叶片中MDA含量呈先降低后增加的趋势;施N显著增加第2茬沙地羊草叶片中POD活性,且N1水平下上部叶片中叶绿素含量增加显著,下部叶中MDA含量降低显著;追施氮肥可提高叶片叶绿素含量,增强叶片POD和SOD活性,推迟羊草衰老。综合不同N水平下活性酶强弱及叶绿素含量变化,科尔沁沙地羊草人工草地建植最佳施氮量为N1(100 kg/hm^2)。

The aim of the current experiment is to explore the effect of N fertilizer on the leaf senescence of Leymus chinensis and provide a theoretical basis for the construction of the artificial grassland of L.chinensis in Horqin area.Different levels of N fertilizer were applied to the artificial cultivated L.chinensis grassland,and the changes of antioxidant enzyme activity,MDA content and chlorophyll content in the leaves of.chinensis under different nitrogen N(0,50 kgN/hm^2,100 kgN/hm^2,150 kgN/hm^2,and 200 kgN/hm^2 are expressed in N0,N1,N2,N3,and N4,respectively) levels were analyzed.The results showed that the application of N fertilizer could significantly increase the activity of SOD,POD and CAT in the leaves of L.chinensis in one crop.With the increase of N fertilizer level,the chlorophyll content of flag leaves,inverted two leaves and third leaf leaves of L.chinensis increased first and then decreased,and the content of MDA in the lower leaves of L.chinensis decreased firstly and then increased in one crop.The application of N fertilizer could significantly increase the POD activity in the leaves of L.chinensis in the second crop,and at N1 level,chlorophyll content in upper leaves increased significantly,while MDA content in lower leaves decreased significantly.Topdressing nitrogen fertilizer can increase photosynthetic efficiency and delay the senescence of L.chinensis by increasing chlorophyll content,increasing POD and SOD activity in leaves..The optimum nitrogen application rate for L.chinensis artificial grassland in Horqin Sandy Land was N1(100 kgN/hm^2).