排序方式： 共有8条查询结果，搜索用时 15 毫秒
1
1.
Leaf pigment content provides valuable insight into the productivity, physiological and phenological status of vegetation. Measurement of spectral reflectance offers a fast, nondestructive method for pigment estimation. A number of methods were used previously for estimation of leaf pigment content, however, spectral bands employed varied widely among the models and data used. Our objective was to find informative spectral bands in three types of models, vegetation indices (VI), neural network (NN) and partial least squares (PLS) regression, for estimating leaf chlorophyll (Chl) and carotenoids (Car) contents of three unrelated tree species and to assess the accuracy of the models using a minimal number of bands. The bands selected by PLS, NN and VIs were in close agreement and did not depend on the data used. The results of the uninformative variable elimination PLS approach, where the reliability parameter was used as an indicator of the information contained in the spectral bands, confirmed the bands selected by the VIs, NN, and PLS models. All three types of models were able to accurately estimate Chl content with coefficient of variation below 12% for all three species with VI showing the best performance. NN and PLS using reflectance in four spectral bands were able to estimate accurately Car content with coefficient of variation below 14%. The quantitative framework presented here offers a new way of estimating foliar pigment content not requiring model re-parameterization for different species. The approach was tested using the spectral bands of the future Sentinel-2 satellite and the results of these simulations showed that accurate pigment estimation from satellite would be possible. 相似文献
2.
许多研究已经表明，类胡萝卜素是分布最广泛、最重要的一类光辅助合成色素。类胡萝卜素具有多种生物学功能：作为化学保护剂可抵抗由植物自身叶绿素的光敏氧化作用引起的有害作用，给人体补充β-胡萝卜素可有效降低心血管疾病和癌症的发生概率，高摄入富含类胡萝卜素的饮食和降低白内障发生的危险之间有重要联系(Bendich，1993)。海藻中含有丰富的类胡萝卜素，从结构类型说，通常可以分为三类：胡萝卜素、叶黄素和类胡萝卜素酸。海藻中还含有多种特有的类胡萝卜素，如褐藻黄素、甲藻黄素、硅藻黄素等。直到目前为止，海藻中类胡萝卜素的组成与生理学功能尚没有明确的结论，因而对我国丰富的海藻资源中的类胡萝卜素进行较为系统和全面的化学及生物活性研究已成为摆在我们面前的一个重要课题。本研究选取我国青岛海滨三类大型经济海藻——红、绿、褐藻中资源量丰富的代表性种类作为实验材料，较系统地测定了其中类胡萝卜素的含量，并运用经典的柱层析法对各类胡萝卜素组分进行了分离，通过薄层分析和可见光谱扫描对各分离组分进行了定性、定量分析。 相似文献
3.
盐度对隐杆藻类胡萝卜素及脂肪酸含量的影响 总被引：2，自引：0，他引：2
于1992年6月，采集分离江苏台南盐场盐生隐杆藻，通过不同浓度的NaCl研究盐度对类胡萝卜素、脂肪酸含量的影响；类胡萝卜素，依Jones等（1974）方法提取，脂肪酸依Schwarzenbach等（1978）方法提取。结果表明，在0．5—1．5mol／LNaCl培养基中，类胡萝卜素的百分含量从2．76％下降到0．67％；然而当培养基NaCl浓度增加到3.5mol／L时，类胡萝卜素的百分含量又开始上升，到2.31％。在低盐度（NaCl，0．5－1．0mol／L）和高盐度NaCl，3．0－3．5mol／U）下培养的盐生隐杆藻中，总脂肪酸的含量高于中盐度（NaCl，10－25mol／L）的；软脂肪酸含量变化同总脂肪酸相似；此外，在不同盐度下各种脂肪酸的相对百分含量也是变化的。 相似文献
4.
太湖蓝藻中天然色素的分离提取及测定 总被引：9，自引：2，他引：9
本文对太湖蓝藻中的叶绿素，胡萝卜素，藻蓝素等天然色素进行分离提以，并运用紫外可见分光光度法对色素含量进行测定；最后对色素在食品，化妆品等方面的应用进行了初步探讨。 相似文献
5.
MacFarlane GR 《Marine pollution bulletin》2002,44(3):244-256
Sediment loadings and leaf accumulation of the heavy metals copper (Cu), lead (Pb) and zinc (Zn) with accompanying changes in leaf chlorophylls' (a + b), carotenoids and the antioxidant enzyme peroxidase were examined in the grey mangrove Avicennia marina (Forsk.) Vierh, in order to determine the applicability of these parameters as biomarkers of heavy metal stress under field conditions. Copper was found to show limited accumulation to leaf tissue, following a linear relationship at lower sediment concentrations, with saturation at higher sediment Cu concentrations. Copper accumulation relationships to leaf tissue were maintained temporally, and increases in sediment Cu, salinity, and decreases in sediment pH and Zn contributed to the accumulation of Cu to leaf tissue. Lead showed a significant relationship between sediment and leaf Pb levels, but accumulation was minimal. Accumulation relationships for Pb were not maintained temporally, and high sediment Pb, low pH and organic content increased bioavailability and accumulation of Pb. Zinc was the most mobile of all metals and was accumulated to the greatest quantities in leaf tissue in a dose-dependant relationship. Some temporal variation in Zn accumulation occurred, and higher sediment pH, organic content Zn and Pb promoted leaf Zn accumulation. Leaf Cu and Zn showed the strongest relationship with peroxidase activity and to a lesser degree Pb. Zinc was the only accumulated metal to show relationship maintenance with peroxidase activity over time. It was found that peroxidase activity best reflects the total phytotoxic effect from the combined metal stress of all three accumulated leaf metals. The only significant photopigment relationship evidenced was that of leaf Zn with the chlorophyll a/b ratio, but was not maintained temporally. Peroxidase activity may be an appropriate biomarker for Zn or total metal accumulation in leaf tissue, and the chlorophyll a/b ratio a suitable biomarker of Zn accumulation though requires temporal monitoring under field conditions. 相似文献
6.
Forests play an important role in regulation of the global climate; moreover, they provide human beings with a whole range of ecosystem services. Forest health and ecosystem functioning have been influenced by anthropogenic activities and their consequences, such as air pollution, surface mining, heavy metal contamination, and other biotic and abiotic stress factors, which had an especially serious effect on central Europe. Many aspects of the physiological state of trees are more or less related to the concentrations of two main groups of leaf photosynthetic pigments: chlorophylls and carotenoids. Therefore, their contents can be used as non-specific indicators of the actual tree physiological status, stress and the pre-visible tree damage. Variations in leaf biochemical composition affect foliar optical properties and can be assessed remotely using high spectral resolution data (hyperspectral data). These data were successfully used in earlier studies to detect vegetation stress and damage. However, only a few approaches have dealt with the use of hyperspectral remote sensing to assess vegetation physiological status on a regional scale. Moreover, little or no research has been done on assessing vegetation health while utilizing multi-date hyperspectral images.In this study, the method for assessing forest health conditions using optical indices retrieved from hyperspectral data was applied to the two temporal HyMap date sets acquired in 07/2009 and 08/2010 to detect stress for the Norway spruce forests in Sokolov, NW Bohemia, a region affected by long-term extensive mining. The classification results were validated by ground truth data (total chlorophyll – Cab, carotenoids – Car and carotenoid to chlorophyll ratio – Car/Cab) and were associated with the geochemical conditions of the forest stands. Both biochemical analysis of the sampled foliage and classification of 2009 and 2010 hyperspectral image identified the same sites affected by vegetation stress. In addition to higher Car/Cab, which enabled detection of the stressed trees using hyperspectral image data, these sites showed critically low pH and lower values for the macronutrient parameters in both organic horizons and, in addition, both sites exhibit critically low base cation to aluminum ratios (Bc/Al) for lower organic and top mineral (0–20 cm) soil horizons.The results of this study demonstrate (i) the potential application of hyperspectral remote sensing as a rapid method of identifying tree stress prior to symptom expression, and (ii) the added value of multi-temporal approaches for hyperspectral data and its further potential for monitoring forest ecosystems. 相似文献
7.
Experimental determination of carotenoid degradation 总被引：1，自引：0，他引：1
P. R. Leavitt 《Journal of Paleolimnology》1988,1(3):215-227
8.
This paper examines the use of canopy reflectance for different units of measurements of carotenoids estimation. Field spectral measurements were collected over cotton in different intensive field campaigns organized during the growing seasons of 2010 and 2011. Three units of measurement were evaluated carotenoids expressed as a mass per unit soil surface area (g/m2), a mass per unit leaf area (μg/cm2), and a mass per unit fresh leaf weight (mg/g), respectively. Four methods were compared to retrieve amount of carotenoids: stepwise multiple linear regression (SMLR), published spectral indices, band combination indices, and partial least square regression (PLSR). Results show that maximum sensitivity of reflectance to variation in different units of measurement of carotenoids was found in the green region at 515–550 nm, and at 715 nm and 750 nm regions in the far-red wavelengths. The predictive accuracies of Car (g/m2), Car (μg/cm2) and Car (mg/g) were tested on a validation data set and the results show that the highest R2 values between estimations and observations were 0.468 for Car (g/m2), 0.563 for Car (μg/cm2), and 0.456 for Car (mg/g), with relative root mean square error (RMSE%, RMSE/mean) of 48.72%, 22.07% and 21.07%, respectively. Compared to Car (g/m2) and Car (mg/g), the model performance indices for Car (μg/cm2) show a high degree of consistency among the R2 values and RMSE% and MAE% values. Further comparison were performed among the estimation accuracies of different unit carotenoids and among the different approaches used in the study by a paired-t-test. The results indicate that although the best estimation results for Car (μg/cm2) and Car (mg/g) were both obtained based on PLSR, they can be estimated by all four adopted methods without significant differences (P > 0.1). Whereas for Car (g/m2), the best estimation results were obtained based on published vegetation indices CIred-edge, which were significantly better than the estimation results based on SMLR (P < 0.000). In summary, the results of this study show that even the carotenoids expressed on concentration (mg/g) or content (μg/cm2) basis at leaf level can be estimated with the same prediction accuracies to the carotenoids expressed as a mass per unit surface area (g/m2) at canopy level using reflectance measurement at canopy level. 相似文献
1