地物反射光谱的测试

本文讨论了双向反射率分布函数、双向反射率、双向反射率因子等光谱反射率之间的关系,并指出了在一定条件下,遥感技术中野外测量地物反射光谱所得的双向反射率因子和物理学中惯用的光谱反射率即半球反射率定义(全部反射光功率与入射光功率之比)是完全一致的.最后还讨论了在野外测量地物反射光谱时需要注意的几个具体问题.     

近红外光谱分析技术在测定饲料中植酸磷含量上的应用

植酸是一种抗营养因子。传统的用三氯化铁沉淀植酸的化学分析法费时费工,不能满足饲料工业发展的需要。为了寻求快速检测饲料中植酸磷(简称P.P.)含量的手段,本试验运用近红外光谱分析技术(简称 NIRS),分别以植酸磷含量较高的米糠饼和植酸磷含量较低的高粱为样品,对这两种饲料的化学分析法测值与近红外光谱法测值进行了比较。试验结果表明:用48个米糠饼样品和50个高粱样品进行定标,相关系数(R,下同)分别为0.901和0.890,残余标准差(RSD,下同)分别为0.06和0.03;另用不参与定标的25个米糠饼样品和21个高粱样品对定标结果进行检验,R 分别为0.803和0.917,RSD 分别为0.07和0.02。NIRS 法的分析精度基本上可以达到化学分析法的要求。作者认为,达项技术作为饲料中 PP 含量快速分析的手段是可行的。     

几种热控涂层的真空-紫外辐照试验

无机热控涂层是航天器常用的一类热控涂层。文章采用上海硅酸盐研究所研制的真空－紫外辐照装置,选用合适的加速倍率,对国内几种常用的热控涂层进行了10000ESH以上的辐照试验,原位测量了各阶段试验样品的太阳吸收比,获得了这些热控涂层的太阳吸收比变化曲线,验证了热控涂层的“漂白效应”。相关研究结果可以为热控制专家进行热设计时提供参考。     

Cow‐specific diet digestibility predictions based on near‐infrared reflectance spectroscopy scans of faecal samples

This study was designed to obtain information on prediction of diet digestibility from near‐infrared reflectance spectroscopy (NIRS) scans of faecal spot samples from dairy cows at different stages of lactation and to develop a faecal sampling protocol. NIRS was used to predict diet organic matter digestibility (OMD) and indigestible neutral detergent fibre content (iNDF) from faecal samples, and dry matter digestibility (DMD) using iNDF in feed and faecal samples as an internal marker. Acid‐insoluble ash (AIA) as an internal digestibility marker was used as a reference method to evaluate the reliability of NIRS predictions. Feed and composite faecal samples were collected from 44 cows at approximately 50, 150 and 250 days in milk (DIM). The estimated standard deviation for cow‐specific organic matter digestibility analysed by AIA was 12.3 g/kg, which is small considering that the average was 724 g/kg. The phenotypic correlation between direct faecal OMD prediction by NIRS and OMD by AIA over the lactation was 0.51. The low repeatability and small variability estimates for direct OMD predictions by NIRS were not accurate enough to quantify small differences in OMD between cows. In contrast to OMD, the repeatability estimates for DMD by iNDF and especially for direct faecal iNDF predictions were 0.32 and 0.46, respectively, indicating that developing of NIRS predictions for cow‐specific digestibility is possible. A data subset of 20 cows with daily individual faecal samples was used to develop an on‐farm sampling protocol. Based on the assessment of correlations between individual sample combinations and composite samples as well as repeatability estimates for individual sample combinations, we found that collecting up to three individual samples yields a representative composite sample. Collection of samples from all the cows of a herd every third month might be a good choice, because it would yield a better accuracy.     

高光谱遥感估测大豆冠层生长和籽粒产量的探讨

现代作物育种需要监测大量育种材料的生长并估测产量潜势, 高光谱遥感技术为此提供了简单、快捷、非损伤性测定的可能途径。选取30份大豆育成品种进行连续2年的产量比较试验, 在盛花期(R2)、盛荚期(R4)和鼓粒始期(R5)测定地上部生物量(ADM)和叶面积指数(LAI), 并利用ASD高光谱地物仪同步收集大豆冠层反射光谱信息。供试品种间ADM、LAI和产量差异显著或极显著。不同生育期可见光和近红外区域的光谱反射率与大豆ADM、LAI及产量均有显著相关, 尤其在R4和R5期相关性最高。在构建大量光谱参数的基础上, 遴选出对ADM、LAI及产量预测精度较好的回归模型。其中, R5期的P_Area560光谱参数与LAI和R4期的V_Area1450光谱参数与ADM构建的两个生长性状的监测模型效果最好, 决定系数(R²)分别为0.582和0.692。未发现单一生育期光谱参数对大豆估产的有效模型, 但综合R2期NPH1280、R4期V_Area1190以及R5期NPH560构建的产量估测模型, 决定系数(R²)达到0.68, 效果较好。本研究     

不同条件下夏玉米冠层反射光谱响应特性的研究

通过对两个年份不同牛育阶段的田间夏玉米活体进行冠层反射光谱测定,该文分析了不同空间尺度、种植密度、观测角度、生育阶段、叶面积指数KAI、氮素胁迫、叶片含水量以及与杂草共生等8个条件下的冠层反射光谱响应特性,并探讨其发生机理,研究结果表明,夏玉米在不同条件下的冠层反射光谱响应均呈现出一定的规律性.在近红外波段,其反射率值随氮肥施用量的增加而增大,尤以750～1350 nm波段,但在可见光波段,反射率值降低;随着观测探头的逐步升高,反射率值降低:随杂草量的增多,反射率值逐渐增大.这些结果揭示了高光谱遥感田间夏玉米理化信息获取的巨大潜力,同时,为以后遥感反演建模提供了依据.     

颗粒饲料淀粉糊化度的快速检测方法

淀粉糊化度是评价颗粒饲料加工质量的重要指标,直接影响畜禽吸收利用饲料中能量物质的效率,进而影响饲料的转化效率和畜禽生长状态。该文建立了颗粒饲料淀粉糊化度的两种快速检测方法,其中近红外光谱分析方法(NIRS)检测淀粉糊化度的定标和验证模型的决定系数(R2)分别为0.8759和0.9608;而快速黏度分析法(RVA)预测淀粉糊化度的定标和验证模型的决定系数分别为0.8025和0.8746。试验结果表明近红外光谱分析技术和快速黏度分析法均可快速且较准确地预测颗粒饲料的淀粉糊化度,在一定程度上能较好地满足实时监测饲料加工过程淀粉糊化程度、实现颗粒饲料精细加工的需要。     

The use of infrared spectroscopy and machine learning tools for detection of Meloidogyne infestations

Plant parasitic nematodes are generally soilborne pathogens that attack plants and cause economic losses in many crops. The infested plants show nonspecific symptoms or, often, are symptomless; therefore, diagnosis is performed by taking soil and root tissue samples. Here, we show that a combination of different infrared spectra analysis and machine learning algorithms can be used to detect plant parasitic nematode infestations before symptoms become visible, using leaves instead of roots and soil as samples. We found that tomato and guava plants infested with Meloidogyne enterorlobii produced different spectral patterns compared to uninfested plants. Using partial spectra from 1,450 to 900/cm as the "fingerprint region", principal component analyses indicated that after 5 (tomatoes) or 8 weeks (guava), plants with no visible symptoms of infestations were positively diagnosed. To improve the early detection response, we used machine learning modelling. A support vector machine (SVM) was used to obtain more robust, accurate models. The SVM model contained 34 support vectors, 17 for each level. The overall performance of the model was >97% and the total accuracy was significantly higher, demonstrating the absence of chance prediction. The best prediction of infestation was obtained at the second and fourth weeks for tomatoes and guavas, respectively, reducing the diagnostic time by half. The combined application of these techniques reduces the processing time from field to laboratory and shows enormous advantages by avoiding root and soil sampling.     

高温干旱复合胁迫对花生幼苗生理指标的影响

为探讨高温和干旱复合胁迫下的花生幼苗对逆境的响应机制，以抗逆性存在差异的花生品种豫花9719和豫花9326为试验材料，对其幼苗进行昼夜温度为45℃/25℃、土壤含水量为35%~40%左右的高温和干旱复合胁迫处理，研究复合胁迫对花生幼苗生长及生理特性的影响。结果表明：胁迫条件下，豫花9719的株高和干重分别比对照组低44.3%和30.2%，差异达极显著水平；含水量、叶绿素a、叶绿素b、类胡萝卜素、花青素的含量均低于对照，其中叶绿素a的含量低4.88%，差异达显著水平，花青素含量低18.14%，差异达极显著水平；PRI、PI、Gs、Pn值分别比其对照组低12%、50.31%、75.2%、72.3%，差异均达极显著水平；MDA含量和相对电导率分别比对照组高93.1%和29.93%，差异均达显著水平；可溶性蛋白和类黄酮含量分别比对照组高104.5%和41.00%，差异均达显著水平；SOD和CAT活性分别比对照组低0.91%和3.29%，差异不显著。豫花9326的株高比其对照组低33.6%，差异达极显著水平，干重降幅不显著；含水量、类胡萝卜素、花青素的含量均比对照组低，但差异均不显著；叶绿素a和叶绿素b的含量分别比对照组高19.44%和3.39%，其中叶绿素a差异达极显著水平； PRI、PI、Gs、Pn值均比对照低，差异均不显著；MDA含量和相对电导率均比对照组高，但差异均不显著；可溶性蛋白和类黄酮含量分别比对照组高271.33%和48.96%，差异均达极显著水平；SOD和CAT活性分别比对照组高70.11%和68.8%，增幅均达显著水平。推测豫花9326对高温和干旱复合胁迫的抗性较高，主要与其较为强大的抗氧化防御系统及光合系统有关。