地面高光谱和低空遥感监测小麦白粉病初探

利用手持式高光谱仪和基于数字技术的低空遥感系统，对不同严重度小麦白粉病冠层光谱反射率进行了测定，同时调查病情指数，分析不同时期地面平台光谱反射率与病情指数及低空遥感平台反射率与病情指数（disease index，DI）、归一化植被指数（normalized difference vegetable index，NDVI）相关性。结果表明，地面光谱测量冠层光谱反射率和低空遥感数字图像反射率与小麦白粉病病情指数在灌浆期有显著的相关关系，就地面测量结果而言，近红外波段的相关性高于绿光波段，相关系数分别为0．79和0．54；低空遥感数字图像红、绿、蓝三波段中，相关性依次降低，相关系数分别为0．79、0．75和0．62；而且低空遥感图像与归一化植被指数也存在较好的相关关系，蓝、红、绿波段，相关系数依次为0．70、0．68和0．54。这表明利用遥感非破坏性监测小麦白粉痛有着良好的应用前景，对于小麦白粉病发生面积监测有重要意义。     

Tracing Sediment Sources Using Mid‐infrared Spectroscopy in Arvorezinha Catchment,Southern Brazil

The widespread adoption of the sediment fingerprinting approach to guide catchment management has been limited by the cost and the difficulty to prepare and process samples for geochemical and radionuclide analyses. Spectral properties have recently been shown to provide a rapid and cost‐efficient alternative for this purpose. The current research objective was (i) to quantify the sediment source contributions in a 1∙19‐km² rural catchment of Southern Brazil by using mid‐infrared (MIR) spectroscopy and (ii) to compare these results with those obtained with geochemical approach and near‐infrared and ultraviolet–visible spectroscopy methods. The sediment sources to discriminate were cropland surface (n  = 20), unpaved roads (n  = 10) and stream channel banks (n  = 10). Twenty‐nine suspended sediment samples were collected at the catchment outlet during nine significant flood events. The sources could be distinguished by MIR spectroscopy. Cropland and channel bank sources mainly differed in their clay mineral contents, but their similar organic matter content complicated the MIR‐model predictions. Unpaved road contributions were discriminated from the other sources by their lower organic carbon content. When the results of the current research based on MIR spectroscopy are compared with those obtained using other sediment fingerprinting approaches, based on geochemistry and near‐infrared and ultraviolet–visible spectroscopy, an overestimation of channel banks contribution and an underestimation of cropland and unpaved road contributions is found. These results suggest that MIR spectroscopy can provide a useful tool that is non‐destructive, rapid and cheap for tracing sediment sources in rural catchments and for guiding the implementation of soil and water conservation measures. Copyright © 2016 John Wiley & Sons, Ltd.     

Mapping Ridolfia segetum patches in sunflower crop using remote sensing

Ridolfia segetum is a frequent umbelliferous weed in sunflower crops in the Mediterranean basin. Field and remote sensing research was conducted in 2003 and 2004 over two naturally infested fields to determine the potential of multispectral imagery for discrimination and mapping of R. segetum patches in sunflower crops. The efficiency of the four wavebands blue (B), green (G), red (R) and near‐infrared (NIR), selected vegetation indices and the spectral angle mapper (SAM) classification method were studied using aerial photographs taken in the late vegetative (mid‐May), flowering (mid‐June) and senescence (mid‐July) crop growth stages. Discrimination efficiency of R. segetum patches in sunflower crops is consistently affected by their phenological stages, in this order: flowering > senescence > vegetative. In both fields, R. segetum patches were efficiently discriminated in mid‐June, corresponding to the flowering phase, by using the waveband G, the ratio R/B or SAM with overall accuracies ranging from 85% to 98%. The application of the median‐filtering algorithm to any of the classified images improved the accuracy. Our results suggest that mapping R. segetum weed patches in sunflower to implement site‐specific weed management techniques is feasible with aerial photography when images are taken from 8 to 10 weeks before harvesting.     

红树植物地面反射光谱特征研究

结合使用野外便携式光谱仪对九龙江口红树林保护区白骨壤、秋茄、桐花树3种红树植物的叶冠表观光谱的测量结果,系统分析比较了红树植物叶冠反射光谱特征及其差异;并在一个潮间带底质遥感信息处理平台上对研究地点进行基于表观光谱特征的白骨壤和秋茄的SPOT卫星遥感图像分类;最后讨论了红树光谱研究中存在的问题。     

Spectrophotometrical characteristics in the near infrared region in beech (<Emphasis Type="Italic">Fagus crenata</Emphasis>) and pine (<Emphasis Type="Italic">Pinus densiflora</Emphasis>) litters at the various decomposing stages

We examined the relationships between the absorptional characteristics in the near infrared region and the chemical changes of decomposing beech (Fagus crenata) and pine (Pinus densiflora) litters. Spectra as well as the concentrations of chemical substances approached each other and converged with decomposition, although both initial characteristics differed markedly between beech and pine. This indicated that the fundamental chemical structures were almost the same, although their organochemical composition differed. Specific absorption bands for lignin, polysaccharide, and protein were identified at 2,140 and 1,670 nm, 2,270, 1,720, 1,590, and 1,216 nm, and 2,350 nm, respectively. Absorbance at 1,670 nm, peculiar band of aromatics, showed a positive correlation with lignin concentration, which suggested the relative increment of aromatics due to condensed lignin in decomposing litters. Absorbance at 2,140 nm, characterized as the C–H bond in HRC = CHR, showed a negative correlation with lignin concentration, which suggested the decrements of some structures such as side-chains in lignin polymers unrelated to aromatics. Absorbance at 2,270, 1,720, and 1,216 nm, specified to O–H/C–O/C–H bonds in saccharide, might reflect the change of polysaccharide during decomposition because they showed a positive correlation to polysaccharide concentration. In the same way, absorbance at 2,350 nm, identified to the C–H/CH₂ bonds in protein, showed a negative correlation to nitrogen concentration in decomposing litters, which might indicate that the C–H/CH₂ bonds in protein decreased with decomposition due to microbial consumption of carbon in protein. Our findings suggested the possibility that the spectral changes indicate the litter digestibility during decomposition and that also explain the compositional change in decomposing litters.     

基于高光谱图谱融合技术的英德红茶等级快速无损判别

茶叶等级评价是检测茶叶品质的一项重要技术指标。通过提取红茶高光谱成像技术下的图像特征和光谱特征,构建一种基于图谱融合方法、适用于英德红茶等级评价的快速无损判别模型。首先制备3种不同等级的红茶样本,采用t分布-随机近邻嵌入和主成分分析对光谱数据进行降维可视化分析,然后从影响内在品质角度用连续投影法提取每种化学值的特征波长,通过多模型共识策略和竞争性自适应重加权算法-连续投影法筛选得出表征其内在品质的最佳特征波长组合,并建立基于遗传算法优化支持向量机的等级判别模型;其模型的训练集准确率为88%,预测集准确率为78.33%。为了融合外形纹理差异,先提取最佳特征波长组合对应的高光谱图像;采用图像掩膜消除背景的干扰和采用图像主成分分析消除多波长图像间的冗余信息,然后采用灰度共生矩阵和局部二值化算法提取主成分前三维主成分图像与特征光谱融合,并建立基于特征融合的遗传算法优化支持向量机等级判别模型,且基于第三主成分图像特征融合模型判别效果最佳,训练集准确率提升至98%,预测集准确率提升至96.67%。     

基于机载高光谱端元提取分析棉花生长期光谱变化

【目的】棉花在不同生长期的波谱曲线变化具有规律性,研究其时间序列上的反射光谱变化趋势与规律并监测长势,为基于无人机多光谱、高光谱遥感的作物长势监测提供借鉴和参考。【方法】使用多旋翼无人机搭载Rikola高光谱成像仪,获取棉花从花期到后期之间的高光谱影像。使用纯净像元指数算法和最大单形体体积算法进行端元提取,并以SR-3500光谱仪采集的地面光谱曲线为标准,光谱角度为评价指标,依次从端元提取算法效果、不同航高数据对比、光谱相关性、多期光谱曲线变化趋势等分析。【结果】最大单形体体积算法在60、80、100 m航高下波谱角度结果分别为0.065 8、0.065 9、0.067 7,相较于纯净像元指数算法结果更接近地面光谱仪数据,具有较优的相关性(R²均在0.99以上),且能更好地提取小样本端元。航高对端元提取的影响较小,同种算法在不同航高下提取结果差异均在2%以下。不同生长期棉花波谱曲线变化呈规律性,吸收谷与红边值在7月中旬到达峰值。标准植被指数与比值植被指数在7月上中旬达到最大值(0.841 7、11.630 5),增强型植被指数、差值植被指数、优化土壤调节植被指数在7月中下旬达到最大值(0.818 9、0.501 3、0.501 2)。【结论】最大单形体体积算法可较好的从棉花高光谱影像中提取出棉花波谱曲线,且100 m为较优的无人机数据采集航高。棉花在7月光合作用最大,对红光的强吸收、近红外波段强反射现象最为明显。     

西鄂尔多斯保护区沙冬青高光谱特征分析

沙冬青是亚洲荒漠唯一的常绿阔叶灌木,由于分布范围狭小、人为调查困难、资源分布不清,加上人类活动的破坏,其数量正在不断减少。快速、准确识别其生长状况、种群动态对进一步研究沙冬青种群分布及生长监测具有重要意义。采用便携式地物光谱仪测定不同龄级沙冬青反射光谱,利用马氏距离法对其原始光谱、一二阶微分谱特征差异波段选取分析;将冠层原始及其微分光谱与叶片叶绿素含量进行分析。通过其相关性的大小理解沙冬青的生长状况与叶绿素含量间的关系。结果表明:1)不同龄级沙冬青原始光谱曲线趋势较接近,符合植被光谱特征的规律性,幼龄沙冬青反射率差异较明显;不同龄级微分光谱曲线基本一致,幼龄峰值起伏变化显著,极大峰值位于719 nm处,主要受幼龄沙冬青长势的影响;2)通过分析得出马氏距离法对不同龄级沙冬青光谱差异显著波段的选择具有显著性,且所选择波段均为光谱特征波段;3)冠层光谱与叶绿素相关性分析得出不同龄级与叶绿素的敏感波长均为<740 nm的可见光波长范围内,说明可见光波段属于沙冬青叶绿素光谱反应的敏感波;与原始光谱相比,经过导数处理的微分光谱与叶片叶绿素的相关性更高,且相关性大的波段数明显增加。     

Proteomic Characterization of Equine Cerebrospinal Fluid

Cerebrospinal fluid (CSF) is a biofluid that is reflective of overall health. Although proteomic profiling of human CSF has been performed in the context of a variety of disease states, this report represents the first comprehensive proteomic analysis of equine CSF. A total of 320 proteins were confidently identified across six healthy horses, and these proteins were further characterized by gene ontology terms mapped in UniProt, and normalized spectral abundance factors were calculated as a measure of relative abundance. Theses results provide an optimized protocol for analysis of equine CSF and lay the groundwork for future studies involving the study of equine CSF in the context of pathogenic disease states.     

反射光谱法估计小麦叶片表皮蜡质含量的初步研究

为了探讨利用冠层反射光谱技术估计小麦叶片表皮蜡质含量的可行性,以小麦高叶片表皮蜡质含量材料2912与低叶片表皮蜡质含量品种普冰201和晋麦47及其杂交构建的F2:3株系为材料,通过氯仿提取称重法测定了小麦抽穗期的旗叶表皮蜡质含量,并采用FieldSpec 3测定了冠层反射光谱,分析小麦冠层反射光谱与叶片表皮蜡质含量之间的关系。结果表明,三个亲本以及株系间蜡质含量差异显著。高蜡质材料的可见光波段反射率整体高于低蜡质材料,短波长波段光谱反射率与叶片表皮蜡质含量相关性较高。以550和675nm波长的反射光谱为基础的单波/差值指数[R550/(R550-R675)]能较好地反映小麦叶片蜡质含量,两F2:3群体拟合模型的r2值分别为0.761和0.679,回归方程分别为y=0.07x-0.575和y=0.088x-1.481。