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首页> 中文期刊> 《农业工程学报》 >基于高光谱的冬油菜植株氮素积累量监测模型

基于高光谱的冬油菜植株氮素积累量监测模型

         
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摘要

Quick, non-destructive and accurate monitoring and diagnosis of plant nitrogen accumulation (PNA) is important for site-specific N management in winter oilseed rape production. To develop a method for determining PNA of winter oilseed rape (Brassica napusL.) with the hyperspectral techniques, field experiments were carried out for two growing seasons (2013-2014 and 2014-2015) at Meichuan town (30°06′47′′ N, 115°35′35′′ E), Hubei province, China. Rapeseed cultivar of Huayouza No. 9 (with low glucosinolate and erucic acid concentrations) was chosen as the test cultivar. Five N (as urea) fertilization rates were applied in the 2013-2014 growing season, i.e., 0 (N0), 90 (N90), 180 (N180), 270(N270) and 360 kg/hm2(N360). Additionally, for further examining the effects of N status on crop growth and spectral reflectance characteristics, three additional N rates, 45 (N45), 135 (N135) and 225 kg/hm2 (N225) were applied in the 2014-2015 growing season. Canopy hyperspectral reflectance and PNA under different N application rates at seedling, budding and flowering stage during the two growing seasons were measured separately using a Field Spec Pro spectrometer (Analytical Spectral Devices Inc. (ASD), Boulder, CO, USA) and chemical assays in the laboratory. Using linear and nonlinear regression methods, the estimate model for PNA of winter oilseed rape was built on the basis of the experiment data in 2013-2014 acted as training data set, and its precision had been evaluated and tested based on the experiment data in 2014-2015 acted as testing data set. The coefficient of determination (R2), relative root mean square error (RRMSE) and mean relative error (MRE) were used to evaluate the fitness between observed and predicted PNA values. The following sensitivity analysis method, Noise Equivalent (NE) model was calculated to assess the sensitivity of the optimal spectral parameters for detecting changes in PNA across different growth stages. The results indicated that PNA in winter oilseed rape increased with N fertilization rates, and changes in canopy hyperspectral reflectance under varied N rates were all highly significant and consistent in patterns across different growth stages and years. Compared with single reflectance measures, the simple reflectance ratio was more satisfied with its sound correlations with the PNA. PNA were highly and linearly correlated with spectral reflectance ratio of 1 259 nm and 492 nm (R1259/R492) with the highestR2 values (0.850). Upon the analysis the linear and nonlinear (logarithm, parabola, power and exponential) regression models for PNA estimation, and the selected optimal spectral parameters, e.g., ratio vegetation index-5 (RVI-5), normalized difference spectral index (NDSI), red-edge position with linear interpolation method (REIP), triangle vegetation index (TVI), first derivative of the reflectance spectra at the given wavelength at 742 nm (FD742) and the sum of first derivative with the red-edge region (SDR) had a good correlation with PNA (averagedR2 and standard error (SE) was 0.69 and 42.70, respectively), and the best spectral parameter was FD742 (R2=0.79,SE=35.66). Based on the results of precision analysis, the model in which the optimum reflectance ratios (R1259/R492) and first derivative of the reflectance spectra at the given wavelength at 742 nm (FD742) as variables would be perfect of estimating PNA of winter oilseed rape using hyperspectral techniques. The two spectral parameters had the relative lower Noise Equivalent (NE) values and would be not affected by growing stages. The model estimation accuracy was high, theR2 values were 0.98 and 0.98, respectively, the RRMSE values were 0.73 and 0.72, and the MRE values were 14.42 % and 10.31 %, respectively. The overall results indicate that the PNA of winter oilseed rape could be reliably estimated with the canopy hyperspectral methods established in this study.%为无损和定量研究高光谱技术在冬油菜植株氮素积累量(PNA, plant nitrogen accumulation)时空变化监测的适宜性及准确性,该文以两年田间氮肥水平试验为基础,采用单变量线性和非线性回归方法,建立基于特征光谱参数的冬油菜P NA高光谱估算模型.结果表明,采用比值光谱的方法可显著提高冬油菜冠层光谱反射率与PNA间的相关性,其最佳的波段组合为1 259 nm与492 nm处光谱反射率比值(R1259/R492),决定系数R2为0.85.高光谱参数间,以比值植被指数(RVI-5)、归一化光谱指数(NDSI)、线性内插法红边位置(REIP)、三角植被指数(TVI)、742 nm处一阶微分光谱值(FD742)和红边面积(SDR)等光谱参数与PNA相关性较好(平均R2和标准误SE分别为0.69和42.70),且以FD742表现最优(R2=0.79,SE=35.66).精度分析结果显示,以光谱参数R1259/R492和FD742为自变量的指数方程模型作为高光谱监测油菜PNA的最佳模型,各生育期Noise Equivalent(NE)均较低且表现稳定,同时模型估测精度较高,R2分别为0.98和0.98,相对均方根误差RRMSE分别为0.73和0.72,相对误差MRE分别为14.42%和10.31%.该方法为快捷和精确评估冬油菜PNA提供了新的研究思路.

著录项

  • 来源
    《农业工程学报》 |2015年第20期|147-156|共10页
  • 作者

    李岚涛; 马驿; 魏全全; 汪善勤; 任涛; 李小坤; 丛日环; 王振; 王少华;

  • 作者单位

    华中农业大学资源与环境学院,武汉 430070;

    农业部长江中下游耕地保育重点实验室,武汉 430070;

    农业部长江中下游耕地保育重点实验室,武汉 430070;

    华中农业大学资源与环境学院,武汉 430070;

    农业部长江中下游耕地保育重点实验室,武汉 430070;

    农业部长江中下游耕地保育重点实验室,武汉 430070;

    华中农业大学资源与环境学院,武汉 430070;

    农业部长江中下游耕地保育重点实验室,武汉 430070;

    华中农业大学资源与环境学院,武汉 430070;

    农业部长江中下游耕地保育重点实验室,武汉 430070;

    华中农业大学资源与环境学院,武汉 430070;

    农业部长江中下游耕地保育重点实验室,武汉 430070;

    湖北省武穴市农业局,武穴 435400;

    湖北省武穴市农业局,武穴 435400;

  • 原文格式 PDF
  • 正文语种 chi
  • 中图分类 油菜籽（芸薹）;遥感技术在农业上的应用;
  • 关键词

    光谱; 氮; 模型; 植株氮素积累量; 高光谱参数; 最优光谱比值;

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