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21.
Jan StuckensSebinasi Dzikiti Willem W. Verstraeten Stephan Verreynne Rony Swennen Pol Coppin 《Agricultural and Forest Meteorology》2011,151(7):1002-1015
Hyperspectral remote sensing for monitoring horticultural production systems requires the understanding of how plant physiology, canopy structure, management and solar elevation affect the retrieved canopy reflectance during different stages of the phenological cycle. Hence, the objective of this study was to set up and to interpret a hyperspectral time series for a mature and healthy citrus orchard in the Western Cape province of South Africa considering these effects. Based on the remotely sensed data, biophysical parameters at the canopy level were derived and related to known observed physiological and phenological changes at the leaf level and to orchard management. Fractions of mature fruit, flowers, and sunburnt leaves were considered, and indices related to canopy structure chlorophyll content and canopy water status were calculated.Results revealed small cover fractions of mature fruit, flowers and sunburnt leaves of respectively 2.1%, 3.1% and 7.0%, but the high spectral contrast between flowers and leaves allowed a successful classification of flowering intensity. Furthermore, it was shown that canopy level time series of vegetation indices were sensitive to changes in solar elevation and soil reflectance which could be reduced by applying an empirical soil line correction for the most affected indices. Most trends in vegetation indices at the canopy level could be explained by a combination of changes at the leaf level (chlorophyll, carotenoids, dry matter), changes in canopy structure (leaf area index and leaf angle distribution) and changes in cover fractions of vegetative flushes, flowers and sunburnt leaves. The transformed chlorophyll absorption ratio index over the optimised soil adjusted vegetation index (MCARI/OSAVI) was best related to leaf level trends in chlorophyll content. Seasonal changes in the photochemical reflectance index (PRI) were linked to inverse changes in the carotenoid-to-chlorophyll ratio. Canopy structure indices (the modified triangular vegetation index or MTVI2 and the standardized leaf area index determining index or sLAIDI) were sensitive to changes in leaf area index, average leaf angle as well to management interactions (pruning and harvest). Canopy water status was highly impacted during the spring flush due to expanding leaves that concealed trends in the underlying mature leaves. Seasonal trends in soil and weeds reflectance were related to changes in volumetric soil water content and to the earlier and reduced growth period of non-irrigated weeds. 相似文献
22.
Impact of xylanases with different substrate selectivity on gluten-starch separation of wheat flour 总被引:1,自引:0,他引:1
The influence on wheat flour gluten-starch separation of a xylanase from Aspergillus aculeatus (XAA) with hydrolysis selectivity toward water extractable arabinoxylan (WE-AX) and that is not inhibited by wheat flour xylanase inhibitors was compared to that of a xylanase from Bacillus subtilis (XBS) with hydrolysis selectivity toward water unextractable arabinoxylan (WU-AX) and that is inhibited by such inhibitors. XAA improved gluten agglomeration through degradation of WE-AX and concomitant reduction in viscosity, which in the laboratory scale batter procedure with a set of vibrating sieves (400, 250, and 125 microm), increased protein recoveries on the 400 microm sieve. In contrast, XBS had a negative effect as it decreased gluten protein recovery on this sieve, probably as a result of the viscosity increase that accompanied WU-AX solubilization. Hence, it was active even if most likely a considerable part of its activity was prevented by xylanase inhibitors. A combination of XAA and XBS at a low dosage yielded a distribution of gluten proteins on the different sieves comparable to that of the control. At a high combined dosage, the gluten agglomeration was better than that with XAA alone, indicating that both WE-AX and WU-AX have a negative impact on gluten agglomeration. Finally, experiments with endoxylanase addition at different moments during the separation process suggest that the status of the arabinoxylan population during dough mixing is far less critical for its impact on gluten agglomeration than that during the batter phase. 相似文献
23.
Development of an indirect competitive ELISA for flumequine residues in raw milk using chicken egg yolk antibodies 总被引:3,自引:0,他引:3
Van Coillie E De Block J Reybroeck W 《Journal of agricultural and food chemistry》2004,52(16):4975-4978
To detect flumequine in raw milk, an indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed. By carbodiimide conjugation, flumequine was conjugated to cationized bovine serum albumin (cBSA-flumequine) and to cationized ovalbumin (cOVA-flumequine). For the immunization of chickens, cBSA-flumequine was used, which allowed the isolation of specific chicken egg yolk immunoglobulins (IgY) for flumequine. As the coating antigen in the immunoassay, cOVA-flumequine was used. In the indirect competitive assay, standard flumequine was incubated together with the anti-flumequine antibodies. The antibody by which the lowest concentration of free flumequine that gives 50% inhibition of binding (IC50) was found in aqueous dilution was further tested for the applicability to detect flumequine in raw milk. An IC50 level in milk was reached that was about 5 times lower than in aqueous solution. So flumequine can be detected directly in raw milk at maximum residue level (50 microg/kg). No cross-reactivity was noticed with various related quinolones. 相似文献
24.
Carbon sequestration in the agricultural soils of Europe 总被引:6,自引:0,他引:6
In this review, technical and economically viable potentials for carbon sequestration in the agricultural soils of Europe by 2008-2012 are analysed against a business-as-usual scenario. We provide a quantitative estimation of the carbon absorption potential per hectare and the surface of agricultural land that is available and suitable for the implementation of those measures, their environmental effects as well as the effects on farm income. Realistically, agricultural soils in EU-15 can sequester up to 16-19 Mt C year−1 during the first Kyoto commitment period (2008-2012), which is less than one fifth of the theoretical potential and equivalent to 2% of European anthropogenic emissions. We identified as most promising measures: the promotion of organic inputs on arable land instead of grassland, the introduction of perennials (grasses, trees) on arable set-aside land for conservation or biofuel purposes, to promote organic farming, to raise the water table in farmed peatland, and—with restrictions—zero tillage or conservation tillage. Many options have environmental benefits but some risk of increasing N2O emissions. For most measures it is impossible to determine the overall impact on farm profitability. Efficient carbon sequestration in agricultural soils demands a permanent management change and implementation concepts adjusted to local soil, climate and management features in order to allow selection of areas with high carbon sequestering potential. Some of the present agricultural policy schemes have probably helped to maintain carbon stocks in agricultural soils. 相似文献
25.
Application of sequential solvent extraction, followed by HPLC combined with the taste dilution analysis, enabled the localization of the most intense velvety astringent, drying, and puckering astringent, as well as bitter-tasting, compounds in red wine, respectively. Isolation of the taste components involving gel adsorption chromatography, ultrafiltration, and synthesis revealed the identification of 26 sensory-active nonvolatiles, among which several hydroxybenzoic acids, hydroxycinnamic acids, flavon-3-ol glycosides, and dihydroflavon-3-ol rhamnosides as well as a structurally undefined polymeric fraction (>5 kDa) were identified as the key astringent components. In contradiction to literature suggestions, flavan-3-ols were found to be not of major importance for astringency and bitter taste, respectively. Surprisingly, a series of hydroxybenzoic acid ethyl esters and hydroxycinnamic acid ethyl esters were identified as bitter compounds in wine. Taste qualities and taste threshold concentrations of the individual wine components were determined by means of a three-alternative forced-choice test and the half-mouth test, respectively. 相似文献
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28.
Sabine Augustin Jan Evers Hans-Peter Dietrich Johannes Eichhorn Thomas Haussmann Regina Icke Ansgar Isenberg Wolfgang Lux Monica Musio Hans Pretzsch Winfried Riek Thomas Rötzer Bernd Schultze Andreas Schulze Jörg Schröder Walter Seidling Nicole Wellbrock Klaus von Wilpert Barbara Wolff 《European Journal of Forest Research》2005,124(4):251-260
In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and
other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system
in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse
effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary
air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring
was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and
feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal
Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives
of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification
and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading
to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected
level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis
(crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative,
as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the
extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.
相似文献
Sabine AugustinEmail: |
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30.
Helena Tukiainen Janne Alahuhta Richard Field Terhi Ala-Hulkko Raino Lampinen Jan Hjort 《Landscape Ecology》2017,32(5):1049-1063