Plant reageert op korte en lange termijn verschillend op lichtkleur : onderscheid effecten fotosynthese en fotomorfogenese
Ieperen, W. van; Heuvelink, E. ; Kierkels, T. - \ 2016
Onder Glas 13 (2016)10. - p. 15 - 17.
kunstlicht - fotosynthese - plantenontwikkeling - fotomorfogenese - proefopzet - fotosynthetische actieve straling - belichting - glastuinbouw - artificial light - photosynthesis - plant development - photomorphogenesis - experimental design - photosynthetically active radiation - illumination - greenhouse horticulture
De inzichten in het effect van lichtkleuren op fotosynthese, vorm en ontwikkeling groeien gestaag. Je zou dan graag willen dat het om simpele relaties gaat, bijvoorbeeld ‘blauw licht opent huidmondjes’. Zo ligt het echter vaak niet. Effecten op korte en lange termijn zijn vaak verschillend en het gaat altijd om de mix van kleuren.
Assessing the spatial variability in peak season CO2exchange characteristics across the Arctic tundra using a light response curve parameterization
Mbufong, H.N. ; Lund, M. ; Aurela, M. ; Molen, M.K. van der - \ 2014
Biogeosciences 11 (2014)17. - ISSN 1726-4170 - p. 4897 - 4912.
carbon-dioxide exchange - net ecosystem exchange - photosynthetically active radiation - growing-season - thermal-acclimation - vascular plants - tussock tundra - climate-change - energy flux - alaska
This paper aims to assess the spatial variability in the response of CO2exchange to irradiance across the Arctic tundra during peak season using light response curve (LRC) parameters. This investigation allows us to better understand the future response of Arctic tundra under climatic change. Peak season data were collected during different years (between 1998 and 2010) using the micrometeorological eddy covariance technique from 12 circumpolar Arctic tundra sites, in the range of 64-74° N. The LRCs were generated for 14 days with peak net ecosystem exchange (NEE) using an NEE-irradiance model. Parameters from LRCs represent site-specific traits and characteristics describing the following: (a) NEE at light saturation (Fcsat), (b) dark respiration (Rd), (c) light use efficiency (a), (d) NEE when light is at 1000 µmol m-2s-1(Fc1000), (e) potential photosynthesis at light saturation (Psat) and (f) the light compensation point (LCP). Parameterization of LRCs was successful in predicting CO2flux dynamics across the Arctic tundra. We did not find any trends in LRC parameters across the whole Arctic tundra but there were indications for temperature and latitudinal differences within sub-regions like Russia and Greenland. Together, leaf area index (LAI) and July temperature had a high explanatory power of the variance in assimilation parameters (Fcsat, Fc1000and Psat, thus illustrating the potential for upscaling CO2exchange for the whole Arctic tundra. Dark respiration was more variable and less correlated to environmental drivers than were assimilation parameters. This indicates the inherent need to include other parameters such as nutrient availability, substrate quantity and quality in flux monitoring activities.
Scientific and technical challenges in remote sensing of plant canopy reflectance and fluorescence
Malenovsky, Z. ; Mishra, K.B. ; Zemek, F. ; Rascher, U. ; Nedbal, L. - \ 2009
Journal of Experimental Botany 60 (2009)11. - ISSN 0022-0957 - p. 2987 - 3004.
laser-induced fluorescence - leaf-area index - light-use efficiency - induced chlorophyll fluorescence - blue-green fluorescence - photosynthetically active radiation - model inversion methods - vegetation biophysical parameters - rotational raman-scattering - net
State-of-the-art optical remote sensing of vegetation canopies is reviewed here to stimulate support from laboratory and field plant research. This overview of recent satellite spectral sensors and the methods used to retrieve remotely quantitative biophysical and biochemical characteristics of vegetation canopies shows that there have been substantial advances in optical remote sensing over the past few decades. Nevertheless, adaptation and transfer of currently available fluorometric methods aboard air- and space-borne platforms can help to eliminate errors and uncertainties in recent remote sensing data interpretation. With this perspective, red and blue-green fluorescence emission as measured in the laboratory and field is reviewed. Remotely sensed plant fluorescence signals have the potential to facilitate a better understanding of vegetation photosynthetic dynamics and primary production on a large scale. The review summarizes several scientific challenges that still need to be resolved to achieve operational fluorescence based remote sensing approaches
Coupled soil-leaf-canopy and atmosphere radiative transfer modeling to simulate hyperspectral multi-angular surface reflectance and TOA radiance data
Verhoef, W. ; Bach, H. - \ 2007
Remote Sensing of Environment 109 (2007)2. - ISSN 0034-4257 - p. 166 - 182.
photosynthetically active radiation - light interaction-model - vegetation canopies - plant-canopy - sail model - scattering - inversion - prospect - spectra - indexes
Coupling radiative transfer models for the soil background and vegetation canopy layers is facilitated by means of the four-stream flux interaction concept and use of the adding method. Also the coupling to a state-of-the-art atmospheric radiative transfer model like MODTRAN4 can be established in this way, thus enabling the realistic simulation of top-of-atmosphere radiances detected by space-borne remote sensing instruments. Possible applications of coupled modeling vary from mission design to parameter retrieval and data assimilation. This paper introduces a modified Hapke soil BRDF model, a robust version of the PROSPECT leaf model, and a modernized canopy radiative transfer model called 4SAIL2. The latter is a hybrid two-layer version of SAIL accommodating horizontal and vertical heterogeneities, featuring improved modeling of the hot spot effect and output of canopy absorptances. The integrated model is simply called SLC (soil¿leaf-canopy) and has been implemented as a speed-optimized Windows DLL which allows efficient use of computer resources even when simulating massive amounts of hyperspectral multi-angular observations. In this paper various examples of possible model output are shown, including simulated satellite image products. First validation results have been obtained from atmospherically corrected hyperspectral multi-angular CHRIS-PROBA data of the Upper Rhine Valley in Germany.