中国农业科学 ›› 2019, Vol. 52 ›› Issue (14): 2425-2435.doi: 10.3864/j.issn.0578-1752.2019.14.004

• 耕作栽培·生理生化·农业信息技术 • 上一篇    下一篇

不同灌溉条件下冬小麦冠层含水量的光谱响应

孙乾1,2,3,顾晓鹤1,2(),孙林3,王淼4,周龙飞1,2,3,杨贵军1,2,李卫国5,束美艳1,2,3   

  1. 1国家农业信息化工程技术研究中心,北京 100097
    2农业部农业遥感机理与定量遥感重点实验室/北京农业信息技术研究中心,北京 100097
    3山东科技大学测绘科学与工程学院,青岛 266590
    4河北省农业技术推广总站,石家庄 050011
    5江苏省农业科学院农业信息研究所,南京 210014
  • 收稿日期:2019-03-05 接受日期:2019-03-29 出版日期:2019-07-16 发布日期:2019-07-26
  • 通讯作者: 顾晓鹤
  • 作者简介:孙乾,E-mail: sunq817@163.com。
  • 基金资助:
    国家重点研发计划(2016YFD0300609);北京市农林科学院创新能力建设专项(KJCX20170705);江苏省重点计划项目(BE2016730)

Spectral Response Analysis of Canopy Water Content of Winter Wheat Under Different Irrigation Conditions

SUN Qian1,2,3,GU XiaoHe1,2(),SUN Lin3,WANG Miao4,ZHOU LongFei1,2,3,YANG GuiJun1,2,LI WeiGuo5,SHU MeiYan1,2,3   

  1. 1National Engineering Research Center for Information Technology in Agriculture, Beijing 100097
    2Key Laboratory of Quantitative Remote Sensing in Agriculture of Ministry of Agriculture/Beijing Research Center for Information Technology in Agriculture, Beijing 100097
    3College of Geomatics, Shandong University of Science and Technology, Qingdao 266590, Shandong
    4Hebei Agricultural Technology Extension General Station, Shijiazhuang 050011
    5Institute of Agricultural Information, Jiangsu Academy of Agricultural Sciences, Nanjing 210014
  • Received:2019-03-05 Accepted:2019-03-29 Online:2019-07-16 Published:2019-07-26
  • Contact: XiaoHe GU

摘要:

【目的】寻找快速、无损地诊断冠层含水量的方法,对冬小麦长势监测、旱情评估及变量灌溉提供技术支持。【方法】基于田间变量灌溉试验,分析生育期、灌溉量对冬小麦冠层含水量的影响,解析冠层光谱对不同灌溉处理下冠层含水量的响应规律,以冠层等效水厚度(EWTc)为表征指标,基于连续小波变换(CWT)技术,构建冬小麦冠层等效水厚度光谱诊断模型,利用独立样本验证模型精度。【结果】冬小麦冠层等效水厚度在生育后期均随着灌溉量的增多而增加,并随着生育进程的推进而减少;冬小麦冠层光谱反射率随着生育进程的推进而降低,在近红外和中红外波段冠层光谱反射率均表现为1水>0.5水>0水;与原始冠层光谱反射率相比,经连续小波变换后的小波系数与冠层等效水厚度相关性在第1、2、3、5、6、7分解尺度均有不同程度的提高,提高幅度在8.40%—26.20%;以第6尺度2 400 nm、第2尺度1 596 nm和第7尺度2 397 nm构建的冠层等效水厚度光谱诊断模型稳定性和精度较好,验证样本决定系数R 2为0.5411,RMSE为0.0127 cm。【结论】冬小麦冠层含水量随着灌溉时间与灌溉量发生规律性变化,在水分敏感波段范围内呈现明显的光谱响应特征,连续小波变换技术可以有效提高冠层光谱特征参量与冠层等效水厚度的相关性,实现冬小麦冠层含水量光谱诊断,可以为冬小麦田间变量灌溉决策提供技术支持。

关键词: 冬小麦, 冠层等效水厚度, 叶面积指数, 灌溉, 连续小波变换, 冠层光谱

Abstract:

【Objective】 Rapid and non-destructive diagnosis of canopy water content is of great significance for monitoring winter wheat growth, drought assessment and variable irrigation. The response of canopy spectrum to canopy water content under different irrigation treatments was analyzed in this study.【Method】Based on field variable irrigation experiments, the influence of growth stage and irrigation water on canopy water content of winter wheat were analyzed. The response rule of canopy spectrum to canopy water content under different irrigation treatments was explained. The canopy equivalent water thickness (EWTc) was used as the characterization index. Based on continuous wavelet transform (CWT), a spectral diagnostic model of EWTc of winter wheat was constructed. The accuracy of the model was verified by independent samples. 【Result】 The results showed that the EWTc of winter wheat increased with the increase of irrigation water in the later growth stage, and decreased with the advance of growth process. The canopy spectral reflectance of winter wheat decreased with the progress of the growth process. The canopy spectral reflectance of winter wheat at different irrigation treatments in near infrared and mid-infrared bands were as follows: 1 water > 0.5 water > 0 water. Compared with the original canopy spectral reflectance, the correlation between wavelet coefficients after continuous wavelet transform and EWTc was improved in different degrees at the decomposition scales of 1, 2, 3, 5, 6 and 7. In addition, the increase ranged from 8.40% to 26.20%. The spectral diagnostic model of canopy equivalent water thickness constructed at 2 400 nm in scale 6, 1 596 nm in scale 2, and 2 397 nm in scale 7 was better in stability and accuracy. The verification sample determined the coefficient R 2=0.5411, and RMSE=0.0127 cm.【Conclusion】The canopy water content of winter wheat changed regularly with irrigation time and irrigation amount, and showed obvious spectral response characteristics in the water sensitive band. Continuous wavelet transform technology could effectively improve the correlation between canopy spectral parameters and canopy equivalent water thickness. The spectral diagnosis of canopy water content of winter wheat was realized. It could provide technical support for variable irrigation decision-making in winter wheat field.

Key words: winter wheat, EWTc, LAI, irrigation, CWT, canopy spectrum