| 摘要: |
| [目的]揭示关中地区夏玉米叶面光谱特性与施氮量间的相关性,探索不同施氮水平下夏玉米叶片含氮量与叶绿素等生化指标及其光谱反射率特征.[方法]在田间设置不同施氮水平(纯氮施用量分为0,120和240 kg/hm2)的试验小区,分别于喇叭期、抽穗期、吐丝期和乳熟期,采用FieldSpec光谱仪于室内标准光源下测定夏玉米叶片的光谱反射率,采用H2SO4-H2O2消煮,连续流动注射分析仪测定叶片氮含量,采用叶绿素仪测定穗位叶片的叶绿素含量,并对所得数据进行相关性分析.[结果]夏玉米叶片含氮量与叶绿素含量之间呈显著相关性,作物施氮水平对叶片的叶绿素含量及含氮量有直接影响;不同施氮水平下夏玉米叶面的反射波谱曲线趋势大致相同,均明显在绿波段(550 nm左右)有1个反射峰,在近红外波段(760～1 070 nm)有1个较高的反射率平台,在近红外波段(760～1 070 nm)处的反射率随氮肥用量的增加而提高,在可见光波段(400～760 nm)处的反射率则正好相反;在可见光波段,不同生长期玉米的叶面光谱反射率表现为乳熟期>抽雄期>喇叭口期>吐丝期,而在近红外波段其光谱反射率表现为乳熟期>喇叭口期>抽雄期>吐丝期;在可见光(400～760 nm)波段处,夏玉米不同生育期叶片的反射率与叶片含氮量及叶绿素含量呈负相关,而在近红外(760～1 070 nm)波段处,除抽雄期外,其余生育期叶片的反射率与叶片含氮量及叶绿素含量均呈正相关,且相关性较为显著;高光谱遥感监测显示,关中地区夏玉米氮素营养水平的敏感时期分别是喇叭口期、吐丝期及乳熟期,敏感波段为可见光波段的500～720 nm和近红外区的760～1 070 nm.[结论]夏玉米的氮营养水平与叶面光谱反射率存在显著的相关性,利用高光谱遥感数据监测关中地区夏玉米的营养状况是可行的. |
| 关键词: 夏玉米 氮营养 叶绿素含量 光谱反射率 光谱特征 |
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| 基金项目:国家自然科学基金项目（30571527）；西北农林科技大学科研专项（2030203146） |
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| Initial study of different nitroger levels on summer corn's spectral characteristics |
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| Abstract: |
| 【Objective】 The sutdy revealed the correlation between spectral reflection and nitrogenous fertilizer of summer corn in Guanzhong area,and explored the nitrogen content,chlorophyll content and spectrum reflection of summer corn leaf in the different nitrogen conditions.【Method】 Experimental sites were set up in the field and the spectrum reflections of different stages were detrmined by FieldSpec in the room,leaf's nitrogen content and cholrophyll content were determined using H2SO4-H2O2 boil method and chlorophyll Meter,and the resulting data were analyzed with the flow Injection Analysis.【Result】 The result indicated that,the correlation between summer corn leaf's nitrogen content and chlorophyll content was distinct.The different nitrogenous fertilization affected nitrogen and chlorophyll content directly.In the different nitrogen levels the reflection spectrum curve tended to be approximately the same.The general spectrum characteristic displays had obvious green band (nearby 550 nm) reflection peak in the index of reflection spectrum curve,and the near-infrared band (760-1 070 nm) had a higher reflection platform.In the near-infrared band place reflection enhanced along with the nitrogenous fertilizer increase,just opposite in the visible light band place with visible light band 400-760 nm,and the leaf surface spectrum reflection displayed:milking stage>tassel stage>trumpet stage>spinning stage,while with infrared band 760-1 070 nm:milking stage,trumpet stage>tassel stage>the spinning stage.At band 400-760 nm,the correlation between spectrum reflection and nitrogen & chlorophyll content was negative,but opposite in the 760-1 070 nm,elativity prominent (except tassel stage).The estimation on summer cron leaf's nitrogen level using hyperspectral remote sensing's sensitive stage was trumpet stage,spinning stage and milking stage in the Guanzhong Area,the sensitive band being 500-720 nm and 760-1 070 nm.【Conclusion】 This shows,the correlation between different nitrogenous fertilizer and summer corn leaf's spectral reflection is very distinct.So it is feasible to observe corn's nutrient with the hyper-spectra data in the Guanzhong Area. |
| Key words: Summer corn Nitragen nutrient chlorophyll content spectral reflection spectral characteristoic |
