fifteen populations of tartary buckwheat (fagopyrum tataricum gaertn.) occurring in habitats with different natural uv-b levels were sampled, and the plants were exposed to enhanced uv-b radiation under field conditions simulating 25% depletion of the stratospheric ozone layer. the experimental design was a 2×15 factorial, with two levels of uv-b radiation (ambient and enhanced uv-b radiation) and plants from 15 populations. the responses of plants in growth, morphology, productivity and in the composition of photosynthetic pigments were measured. the results demonstrated that there were significant differences among populations in responses to uv-b radiation: some populations exhibited a positive effect while others were negatively affected. the uv-b effects on plant traits were correlated with the constitutive values. a principal component analysis (pca) was used to evaluate the overall sensitivity of responses to uv-b radiation. our results suggest that the sensitivity of plants to uv-b radiation is not only associated with the ambient uv-b level in natural habitats but also with the relative growth rate and other factors.
文献 | 量子荧光|微型光纤光谱仪-ag贵宾会
in aloe arborescens mill. leaves, strong sunlight or its combination with drought induces the accumulation of the red keto-carotenoid, rhodoxanthin. simultaneously, the transformation of chloroplasts into chromoplasts accompanied by degradation of thylakoid membranes and formation of plastoglobuli, large in size and number, takes place. depending on stress conditions the build up of rhodoxantin occurred along with the loss of chlorophyll or on the background of relatively high content of the pigment in the leaves.microspectrophotometrical measurements showed the presence of chlorophyll-free plastids and retention of carotenoids during leaf adaptation to strong sunlight. the plastid spectra contained absorption bands of common for higher plants carotenoids together with those of rhodoxantin, with absorption maxima situated in the blue (440–480 nm) and the green ranges of the spectrum, respectively. the studies of whole-leaf optical properties revealed a broad band of rhodoxanthin absorption in the blue–green range peaking near 540–550 nm. within this spectral band the accumulation of rhodoxanthin occurring, probably, in plastoglobuli considerably increased light absorption by stressed aloe leaves. a possible photoprotective function of rhodoxanthin and other carotenoids as an internal light trap analogous to that accomplished by anthocyanins in other plant species is discussed
while most mammals have no more than two types of cone photoreceptor, four species of australian marsupial have recently been shown to possess three types, and thus have the potential for trichromatic colour vision. interestingly, the long-wave cones of the honey possum tarsipes rostratus are tuned to longer wavelengths than those of the other species measured to date. we tested whether the honey possum’s long-wave tuning is adaptive for visual tasks associated with its almost unique diet of nectar and pollen. we modelled three tasks: (1) detecting food-rich ‘target’ flowers against their natural background of foliage or other vegetation; (2) discriminating target flowers from flowers of non-target species; (3) discerning the maturity of the most important target flowers. initial comparisons of trichromacy vs dichromacy generally favoured the former, but interestingly dichromacy was no disadvantage in some cases. for tuning, we found that overall the honey possum’s long-wave tuning is more adaptive than that of the other marsupial species. nevertheless, the optimal tuning for tasks 1 and 2 would be at longer wavelengths still, implying that a different pressure or constraint operates against a further long-wave shift of the honey possum’s l cone tuning. our data show that a possible ecological pressure may be provided by the third task – the difficult and potentially critical discrimination of the maturity of the animal’s major food supply, the flowers of banksia attenuata.
the anthocyanin (anth) content in leaves provides valuable information about the physiological status of plants. thus, there is a need for accurate, efficient, practical methodologies to estimate this biochemical parameter. reflectance measurement is a means of quickly and nondestructively assessing leaf anth content in situ. the objective of this study was to test the overall performance and accuracy of nondestructive techniques for estimating anth content in grapevine leaves. relationships were established between anth content and four vegetation indices: nir (near-infrared)/green, red/green, anthocyanin reflectance index (ari, based on reflectances in bands within the green and the red-edge regions), and a modified anthocyanin reflectance index (mari, based on reflectances in green, red edge, and nir). the algorithms for anth retrieval were calibrated. the accuracy of anth prediction was evaluated using an independent data set containing sampled leaves from two field-grown grape cultivars (saint croix and saint pepin) with no adjustment of the coefficients after initial calibration. although anth in the validation data set was widely variable, from 3 to 45 nmol cm-2, the ari and mari algorithms were capable of accurately predicting anth content in grapevine leaves with a root mean square error below 3 nmol cm-2 and 2.3 nmol cm-2, respectively. such an approach has potential for developing simple hand-held field instrumentation for accurate nondestructive anth estimation and for analyzing digital airborne or satellite imagery to assist in making informed decisions regarding vineyard management.
we measured the attenuation of ultraviolet b (uvb) and ultraviolet a (uva) radiation in 32 streams located within the ontonagon river watershed on the upper peninsula of michigan, usa. attenuation coefficients (kd) of uvb and uva ranged widely among these streams, but generally translated into relatively shallow 1% transmission depths into the water column (2–45 cm for uvb and 6–103 cm for uva). both kd uvb and kd uva were positively correlated with stream dissolved organic c concentration (doc, range 2–35 mg c/l). absorbance coefficients of dissolved matter (ad) of uvb and uva also were strongly correlated with doc. kd uva (but not kd uvb) was weakly related to the concentration of particulate organic c and doc molar absorptivity. doc-specific kd uvb was, on average, higher in streams of our study compared to previously published values from lakes and wetlands. we developed a statistical model that predicts uvb flux to benthic organisms. the model incorporates information on water depth, doc concentration, surface reflectance, and forest canopy cover. this stream-uvb model (sum) predicts very low uvb flux to the benthic areas ofmost wetland and forested streams of this region during cloudless, midsummer days. overall, our results suggest a low likelihood that stream organisms in this region are normally exposed to high levels of ultraviolet radiation because shading is provided by both stream doc and forest canopy.
利用折射率可以建立偏振度与液体密度之间的函数关系.以不同浓度的盐水为例, 通过usb2000 光谱仪测得高光谱偏振信息并计算其密度, 发现在不同入射角度计算不同浓度的盐水密度的最佳波段不同, 在最佳波段范围内计算的盐水密度精度高.当入射角趋近布儒斯特角时最佳波段范围变宽, 可以满足现今遥感技术的要求.该研究结果为遥感技术在监测水体密度方面提供了新的科学依据.
本文的研究目的：通过对翡色翡翠热处理实验的研究，得出与天然红翡难以区分的热处理红翡，既提高了其商业价值又满足了人们对红翡的需求。
随着当前国际环境的不断变化，安全问题变得日益突出。目前广泛应用的安检设备一般都是基于x射线成像原理获得旅客携带包裹信息，对于一些具有易燃易爆的也太危险品（如酒精、汽油、煤油、甲醇等）的检查大多使用可视和气味检测的方法，采用新的手段和方法实现对液体类危险品的检测是当今本领域最为热门的研究课题。近红外光谱分析技术具有灵敏度高、响应速度快等特点，适用于现场快速检测和实时在线分析。本文针对实际情况，研究了用短波近红外光谱法现场快速检测液体的方法。
在测量叶绿素含量的同时, 使用二向反射光度计、usb2000 高光谱仪和偏振装置, 定量测量与计算丁香叶片高光谱偏振信息, 并建立偏振信息-叶绿素含量回归模型。结果表明:当0°偏振时, 叶绿素的含量与其偏振反射比的回归模型为y =4.506 4e -0.056 8x , 复相关指数r2 =0.895 8 ;90°偏振时, 叶绿素的含量与其偏振反射比的回归模型为y =145.79x -1.204 1 , 复相关指数为r2 =0.479 8 ;50°入射角时, 叶绿素的含量与其偏振度的回归模型为y =7 206.7x 6 -20 160x5 22 547x 4 -12 788x 5 3 822.4x 2 -553.72x 30.429,复相关指数为r2 =0.646 4 ;对以上模型进行f 检验, 发现模型中的偏振信息和叶绿素含量之间存在显著的函数关系, 为植被遥感监测和应用提供了理论基础。
根据色度学原理，利用usb2000 光纤光谱仪，量化常见红色宝石的色度学参数，通过比较分析可知，常见红色宝石在色度学方面呈现较明显的区别: 具有近似色调角的红色宝石样品的明度l 的值按照从大到小的顺序排列，分别为碧玺、尖晶石、石榴石、红宝石; 具有近似色调角的红色宝石样品的色度a* 和彩度c* 的值按照从大到小的顺序排列，分别为碧玺、红宝石、尖晶石、石榴石，而色度b* 的值按照从大到小的顺序排列，分别为石榴石、尖晶石、红宝石、碧玺。因此，利用光纤光谱仪、适当的照明方式及参数采集方法，应用色度学原理，可以对常见红色宝石在色度学方面进行初步对比分析。
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