| 基于高光谱指数估测马铃薯植株氮素浓度的敏感波段提取 |
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| 引用本文： | 杨海波,李斐,张加康,杨柳.基于高光谱指数估测马铃薯植株氮素浓度的敏感波段提取[J].植物营养与肥料学报,2020,26(3):541-551. |
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| 作者姓名： | 杨海波 李斐 张加康 杨柳 |
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| 作者单位： | 内蒙古农业大学草原与资源环境学院/内蒙古自治区土壤质量与养分资源重点实验室，呼和浩特 010018 |
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| 基金项目： | 国家自然科学基金项目（41361079）；2018年度内蒙古自治区高等学校“青年科技英才支持计划”（NJYT-18-A08）。 |
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| 摘 要： | 【目的】 基于光谱指数的氮素营养诊断是快速获取作物氮素营养状况的方式之一。其中，利用可见光和近红外波段光谱反射率构建的比率和归一化光谱指数对估测作物氮素营养状况具有重要意义。解决氮素营养诊断过程中存在的指数饱和及数据离散问题，以评价已有比率和归一化光谱指数对马铃薯关键生育时期植株氮素浓度诊断的可行性。 【方法】 2014—2016年在内蒙古武川县和四子王旗，设置了4个不同氮肥梯度的多点田间试验。在马铃薯块茎形成期、块茎膨大期和淀粉积累期，采集试验地和邻近农田马铃薯地上部和块茎样品，分析其氮素含量。并在马铃薯冠层以上50～80 cm采集光谱数据。用试验田数据建立了12个已发表的比率、归一化光谱指数和波段优化光谱指数与马铃薯关键生育时期植株氮素浓度的相关性与估测模型，并用农田马铃薯数据验证模型的精度。 【结果】 马铃薯植株氮素浓度分布范围在1.89%～4.69%，平均氮素浓度为3.30%，变异系数为18.75%；验证集数据来源于农民田块，马铃薯植株氮素浓度分布范围在2.00%～4.92%，平均氮素浓度为3.34%，变异系数为19.27%。蓝紫光400～450 nm和红边690～720 nm波段是马铃薯植株氮素浓度估测的敏感波段，部分已有光谱指数虽然可以用于马铃薯植株氮素浓度的估测，但是蓝紫光波段的缺失大大降低了估测的准确性。通过波段优化算法确定的优化光谱指数RSI、NDSI最佳波段位置分别为430、694和426、694 nm。基于优化光谱指数NDSI (426 nm、694 nm) 建立的马铃薯植株氮素浓度线性估测模型为y=?6.87x+6.08，决定系数R2最高，为0.68；RSI光谱指数与马铃薯植株氮素浓度的线性估测模型为y=?1.11x+5.92，R2为0.65，与已有比率和归一化光谱指数相比，优化光谱指数RSI和NDSI克服了高氮浓度条件下光谱指数饱和现象，显著提高了马铃薯植株氮素浓度的线性建模效果。农民田块验证数据显示，估测模型的估测值与实测值接近1∶1线，其中NDSI光谱指数估测模型的验证效果最佳，平均相对误差RE 和均方根误差RMSE分别为10.58%和0.42%。 【结论】 本研究通过波段优化算法确定了比率和归一化光谱指数的马铃薯植株氮素浓度敏感波段，采用蓝紫光400～450 nm和红边690～720 nm波段进行马铃薯植株氮素浓度估测，可以改善诊断高氮浓度时的指数灵敏度和数据离散问题，提高马铃薯植株氮素营养诊断的精度。
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| 关 键 词： | 马铃薯 光谱指数 植株氮素浓度 高光谱遥感 |
| 收稿时间： | 2019-04-28 |
The deriving of sensitive waveband for the estimation of plant nitrogen concentration in potato based on hyperspectral indices |
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| YANG Hai-bo,LI Fei,ZHANG Jia-kang,YANG Liu.The deriving of sensitive waveband for the estimation of plant nitrogen concentration in potato based on hyperspectral indices[J].Plant Nutrition and Fertilizer Science,2020,26(3):541-551. |
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| Authors: | YANG Hai-bo LI Fei ZHANG Jia-kang YANG Liu |
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| Institution: | College of Grassland, Resources and Environment, Inner Mongolia Agricultural University/Inner Mongolia Key Laboratory of Soil Quality and Nutrient Resource, Hohhot 010018, China |
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| Abstract: | 【Objectives】 Nitrogen nutrition diagnosis based on spectral indices is one of the ways to rapidly obtain nitrogen nutrition status of crops. Among them, the ratio and normalized spectral indices constructed by visible light and near-infrared have important significance for estimating the nitrogen nutrition status of crops. In order to evaluate the feasibility of the existing ratio and the normalized spectral index in the diagnosis of nitrogen concentration in potato plants during the critical growth period, the problems of indices saturation and data dispersion in the diagnosis process of nitrogen nutrition were solved. 【Methods】 From 2014 to 2016, four multi-point field experiments with different nitrogen fertilizer application rates were conducted in Wuchuan County and Siziwang banner, Inner Mongolia. The vine and tuber samples of potato in the tests field and adjacent farmlands were collected to analyze the nitrogen content, and the spectral data were collected 50–80 cm above the potato canopy during potato growth stages of tuber initiation, tuber bulking and starch accumulation. The accuracy of the model was verified by farmland potato data. Correlation and estimation models of 12 published ratios and normalized spectral indices and band-optimized spectral indices with plant nitrogen concentration were built in the critical growth periods of potato. 【Results】 The distribution range of nitrogen concentration in potato plants was 1.89%–4.69%, the average nitrogen concentration was 3.30%, and the coefficient of variation was 18.75%. The data of the verification set were from farmland. And the distribution range of nitrogen concentration in potato plants was 2.00%–4.92%, the average nitrogen concentration was 3.34%, and the coefficient of variation was 19.27%. The experimental results showed that the bands of blue violet at 400–450 nm and red edge at 690–720 nm were the sensitive bands for nitrogen concentration estimation of potato plants. Some existing spectral indexes could be used for nitrogen concentration estimation of potato plants, but the absence of blue violet band greatly reduced the accuracy of estimation. The optimal spectral indices positions of RSI and NDSI were 430 nm, 694 nm and 426 nm, 694 nm, respectively. The linear estimation model of nitrogen concentration of potato plants based on the optimized spectral indices NDSI (426 nm, 694 nm) was y=?6.87x+6.08, with the highest determination coefficient R2 (0.68). The linear estimation model of RSI spectral indices with potato plant nitrogen concentration was y =?1.11x+ 5.92 (R2 =0.65), Compared with the existing ratio and normalized spectral indices, optimization of spectral indices RSI and NDSI overcomed the high nitrogen concentration spectrum index under the condition of low saturation caused by sensitivity phenomenon, and significantly improved the potato plants linear modeling effect of nitrogen concentration in potato plant. The verification data of farmers’ field showed that the estimated value of the estimation model was close to the 1∶1 line with the measured value, and the NDSI spectral indices estimation model had the best verification effect, with the mean relative error RE and root mean square error RMSE being 10.58% and 0.42%, respectively. 【Conclusions】 In this study, the nitrogen concentration sensitive bands of potato plants with ratio and normalized spectral index are determined by band optimization algorithm. Using blue-violet light 400–450 nm and red edge 690–720 nm to estimate nitrogen concentration of potato plants can improve the index sensitivity and data dispersion problem in the diagnosis process of high nitrogen concentration of potato plant, and improve the accuracy of nitrogen nutrition diagnosis of potato plant. |
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