Journal articles on the topic 'Leaf level measurements'
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1
Williams, M. R., and I. Abbott. "Quantifying Average Defoliation Using Leaf-Level Measurements." Ecology 72, no. 4 (August 1991): 1510–11. http://dx.doi.org/10.2307/1941126.
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Baret, Frederic, Simon Madec, Kamran Irfan, Jeremy Lopez, Alexis Comar, Matthieu Hemmerlé, Dan Dutartre, Sebastien Praud, and Marie Helene Tixier. "Leaf-rolling in maize crops: from leaf scoring to canopy-level measurements for phenotyping." Journal of Experimental Botany 69, no. 10 (April 2, 2018): 2705–16. http://dx.doi.org/10.1093/jxb/ery071.
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Rajewicz, Paulina, Jon Atherton, Luis Alonso, and Albert Porcar-Castell. "Leaf-Level Spectral Fluorescence Measurements: Comparing Methodologies for Broadleaves and Needles." Remote Sensing 11, no. 5 (March 5, 2019): 532. http://dx.doi.org/10.3390/rs11050532.
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Successful measurements of chlorophyll fluorescence (ChlF) spectral properties (typically in the wavelength range of 650–850 nm) across plant species, environmental conditions, and stress levels are a first step towards establishing a quantitative link between solar-induced chlorophyll fluorescence (SIF), which can only be measured at discrete ChlF spectral bands, and photosynthetic functionality. Despite its importance and significance, the various methodologies for the estimation of leaf-level ChlF spectral properties have not yet been compared, especially when applied to leaves with complex morphology, such as needles. Here we present, to the best of our knowledge, a first comparison of protocols for measuring leaf-level ChlF spectra: a custom-made system designed to measure ChlF spectra at ambient and 77 K temperatures (optical chamber, OC), the widely used FluoWat leaf clip (FW), and an integrating sphere setup (IS). We test the three methods under low-light conditions, across two broadleaf species and one needle-like species. For the conifer, we characterize the effect of needle arrangements: one needle, three needles, and needle mats with as little gap fraction as technically possible. We also introduce a simple baseline correction method to account for non-fluorescence-related contributions to spectral measurements. Baseline correction was found especially useful in recovering the spectra nearby the filter cut-off. Results show that the shape of the leaf-level ChlF spectra remained largely unaffected by the measurement methodology and geometry in OC and FW methods. Substantially smaller red/far-red ratios were observed in the IS method. The comparison of needle arrangements indicated that needle mats could be a practical solution to investigate temporal changes in ChlF spectra of needle-like leaves as they produced more reproducible results and higher signals.
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Röll, Georg, Jens Hartung, and Simone Graeff-Hönninger. "Determination of Plant Nitrogen Content in Wheat Plants via Spectral Reflectance Measurements: Impact of Leaf Number and Leaf Position." Remote Sensing 11, no. 23 (November 26, 2019): 2794. http://dx.doi.org/10.3390/rs11232794.
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The determination of plant nitrogen (N) content (%) in wheat via destructive lab analysis is expensive and inadequate for precision farming applications. Vegetation indices (VI) based on spectral reflectance can be used to predict plant N content indirectly. For these VI, reflectance from space-borne, airborne, or ground-borne sensors is captured. Measurements are often taken at the canopy level for practical reasons. Hence, translocation processes of nutrients that take place within the plant might be ignored or measurements might be less accurate if nutrient deficiency symptoms occur on the older leaves. This study investigated the impact of leaf number and measurement position on the leaf itself on the determination of plant N content (%) via reflectance measurements. Two hydroponic experiments were carried out. In the first experiment, the N fertilizer amount and growth stage for the determination of N content was varied, while the second experiment focused on a secondary induction of N deficiency due to drought stress. For each plant, reflectance measurements were taken from three leaves (L1, L2, L3) and at three positions on the leaf (P1, P2, P3). In addition, the N content (%) of the whole plant was determined by chemical lab analysis. Reflectance spectrometer measurements (400–1650 nm) were used to calculate 16 VI for each combination of leaf and position. N content (%) was predicted using each VI for each leaf and each position. Significant lower mean residual error variance (MREV) was found for leaves L1 and L3 and for measurement position on P3 in the N trial, but the difference of MREV between the leaves was very low and therefore considered as not relevant. The drought stress trial also led to no significant differences in MREV between leaves and positions. Neither the position on the leaf nor the leaf number had an impact on the accuracy of plant nitrogen determination via spectral reflectance measurements, wherefore measurements taken at the canopy level seem to be a valid approach.
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Zhang, Jing-Cheng, Rui-liang Pu, Ji-hua Wang, Wen-jiang Huang, Lin Yuan, and Ju-hua Luo. "Detecting powdery mildew of winter wheat using leaf level hyperspectral measurements." Computers and Electronics in Agriculture 85 (July 2012): 13–23. http://dx.doi.org/10.1016/j.compag.2012.03.006.
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Umam, Khoirul, and Eko Heri Susanto. "Classification Of Rice Leaf Color Into Leaf Color Chart Using LAB Color Space." CCIT Journal 13, no. 2 (August 27, 2020): 168–74. http://dx.doi.org/10.33050/ccit.v13i2.1008.
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Leaf Color Chart (LCC) is a measurement tool that can be used to measure the color intensity of rice leaves. The function of these measurements is to find out how many doses of fertilizer are needed by rice plants. However, readings made by human vision have a high level of subjectivity and risk of error. Therefore we need a method that can minimize errors and the level of subjectivity. One method that can be done is to classify the green color of rice leaves using LAB color space. Rice leaf image taken using a smartphone device is then extracted in RGB format. The color is then converted to LAB color space and then compared to the standard green color in the LCC. The comparison results are then used to classify the colors. The testing results show that the method has the value of accuracy, average precision, and average recall of 54.74%, 54.44%, and 51.16% respectively. Therefore the method can only classify correctly half of the data testing.
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Perry, Eileen M., Ian Goodwin, and David Cornwall. "Remote Sensing Using Canopy and Leaf Reflectance for Estimating Nitrogen Status in Red-blush Pears." HortScience 53, no. 1 (January 2018): 78–83. http://dx.doi.org/10.21273/hortsci12391-17.
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Reflectance measurements at leaf and canopy scales were made in a red-blush pear (Pyrus communis) orchard for two growing seasons. Canopy reflectance measurements were obtained using a multispectral camera flown on board an unmanned aerial vehicle (UAV), and leaf reflectance measurements were undertaken in a laboratory using a portable spectrometer. These measurements were used to compute reflectance indices as surrogates for direct leaf nitrogen (N) concentration measurements. The indices were evaluated against laboratory analysis of leaf N concentration. Regression results for leaf %N on canopy-level measurements with the multispectral camera resulted in the highest R2 value [R2 = 0.67; root mean square error (RMSE) = 0.24%N] with a new index, Modified Canopy Chlorophyll Content Index (M3CI)_710 nm. Regression results for leaf %N on leaf-level measurements in-laboratory resulted in the highest R2 value (R2 = 0.65) with two other indices, Normalized Difference Vegetation Index (NDVI) and Normalized Difference Red-edge Index (NDRE)_720 nm. The corresponding RMSE values were 0.26%N. The results indicate that reflectance indices measured at the leaf level, with a controlled light source and calibration, could be used to estimate leaf %N. An analysis of uncertainty indicated that if leaf %N is estimated from leaf-level reflectance values, 10 or more leaves (from the same tree) should be averaged. The results support the use of a UAV-based assessment for canopy %N using the M3CI_710 nm, which could provide spatial information of leaf N concentration across an orchard.
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Raulier, F., P. Y. Bernier, and C. H. Ung. "Canopy photosynthesis of sugar maple (Acer saccharum): comparing big-leaf and multilayer extrapolations of leaf-level measurements." Tree Physiology 19, no. 7 (June 1, 1999): 407–20. http://dx.doi.org/10.1093/treephys/19.7.407.
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Riches, Mj, Daniel Lee, and Delphine K. Farmer. "Simultaneous leaf-level measurement of trace gas emissions and photosynthesis with a portable photosynthesis system." Atmospheric Measurement Techniques 13, no. 8 (August 4, 2020): 4123–39. http://dx.doi.org/10.5194/amt-13-4123-2020.
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Abstract. Plants emit considerable quantities of volatile organic compounds (VOCs), the identity and amount of which vary with temperature, light, and other environmental factors. Portable photosynthesis systems are a useful method for simultaneously quantifying in situ leaf-level emissions of VOCs and plant physiology. We present a comprehensive characterization of the LI-6800 portable photosynthesis system's ability to be coupled to trace gas detectors and measure leaf-level trace gas emissions, including limits in flow rates, environmental parameters, and VOC backgrounds. Instrument contaminants from the LI-6800 can be substantial but are dominantly complex molecules such as siloxanes that are structurally dissimilar to biogenic VOCs and thus unlikely to interfere with most leaf-level emissions measurements. We validate the method by comparing CO2 assimilation calculated internally by the portable photosynthesis system to measurements taken with an external CO2 gas analyzer; these assimilation measurements agree within 1 %. We also demonstrate both online and offline measurements of plant trace gas exchange using the LI-6800. Offline measurements by pre-concentration on adsorbent cartridges enable the detection of a broad suite of VOCs, including monoterpenes (e.g., limonene) and aldehydes (e.g., decanal). Online measurements can be more challenging if flow rates require dilution with ultrapure zero air. We use high-resolution time-of-flight chemical ionization mass spectrometry coupled to the LI-6800 to measure the direct plant emission of formic acid.
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Harley, Peter, Luanne Otter, Alex Guenther, and James Greenberg. "Micrometeorological and leaf-level measurements of isoprene emissions from a southern African savanna." Journal of Geophysical Research: Atmospheres 108, no. D13 (February 12, 2003): n/a. http://dx.doi.org/10.1029/2002jd002592.
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Ni, Zhuoya, Zhigang Liu, Hongyuan Huo, Zhao-Liang Li, Françoise Nerry, Qingshan Wang, and Xiaowen Li. "Early Water Stress Detection Using Leaf-Level Measurements of Chlorophyll Fluorescence and Temperature Data." Remote Sensing 7, no. 3 (March 20, 2015): 3232–49. http://dx.doi.org/10.3390/rs70303232.
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Zarco-Tejada, P. "Chlorophyll Fluorescence Effects on Vegetation Apparent Reflectance I. Leaf-Level Measurements and Model Simulation." Remote Sensing of Environment 74, no. 3 (December 2000): 582–95. http://dx.doi.org/10.1016/s0034-4257(00)00148-6.
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Vilà-Guerau de Arellano, Jordi, Patrizia Ney, Oscar Hartogensis, Hugo de Boer, Kevin van Diepen, Dzhaner Emin, Geiske de Groot, et al. "CloudRoots: integration of advanced instrumental techniques and process modelling of sub-hourly and sub-kilometre land–atmosphere interactions." Biogeosciences 17, no. 17 (August 31, 2020): 4375–404. http://dx.doi.org/10.5194/bg-17-4375-2020.
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Abstract. The CloudRoots field experiment was designed to obtain a comprehensive observational dataset that includes soil, plant, and atmospheric variables to investigate the interaction between a heterogeneous land surface and its overlying atmospheric boundary layer at the sub-hourly and sub-kilometre scale. Our findings demonstrate the need to include measurements at leaf level to better understand the relations between stomatal aperture and evapotranspiration (ET) during the growing season at the diurnal scale. Based on these observations, we obtain accurate parameters for the mechanistic representation of photosynthesis and stomatal aperture. Once the new parameters are implemented, the model reproduces the stomatal leaf conductance and the leaf-level photosynthesis satisfactorily. At the canopy scale, we find a consistent diurnal pattern on the contributions of plant transpiration and soil evaporation using different measurement techniques. From highly resolved vertical profile measurements of carbon dioxide (CO2) and other state variables, we infer a profile of the CO2 assimilation in the canopy with non-linear variations with height. Observations taken with a laser scintillometer allow us to quantify the non-steadiness of the surface turbulent fluxes during the rapid changes driven by perturbation of photosynthetically active radiation by cloud flecks. More specifically, we find 2 min delays between the cloud radiation perturbation and ET. To study the relevance of advection and surface heterogeneity for the land–atmosphere interaction, we employ a coupled surface–atmospheric conceptual model that integrates the surface and upper-air observations made at different scales from leaf to the landscape. At the landscape scale, we calculate a composite sensible heat flux by weighting measured fluxes with two different land use categories, which is consistent with the diurnal evolution of the boundary layer depth. Using sun-induced fluorescence measurements, we also quantify the spatial variability of ET and find large variations at the sub-kilometre scale around the CloudRoots site. Our study shows that throughout the entire growing season, the wide variations in stomatal opening and photosynthesis lead to large diurnal variations of plant transpiration at the leaf, plant, canopy, and landscape scales. Integrating different advanced instrumental techniques with modelling also enables us to determine variations of ET that depend on the scale where the measurement were taken and on the plant growing stage.
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Aasen, Van Wittenberghe, Medina, Damm, Goulas, Wieneke, Hueni, et al. "Sun-Induced Chlorophyll Fluorescence II: Review of Passive Measurement Setups, Protocols, and Their Application at the Leaf to Canopy Level." Remote Sensing 11, no. 8 (April 16, 2019): 927. http://dx.doi.org/10.3390/rs11080927.
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Imaging and non-imaging spectroscopy employed in the field and from aircraft is frequently used to assess biochemical, structural, and functional plant traits, as well as their dynamics in an environmental matrix. With the increasing availability of high-resolution spectroradiometers, it has become feasible to measure fine spectral features, such as those needed to estimate sun-induced chlorophyll fluorescence (F), which is a signal related to the photosynthetic process of plants. The measurement of F requires highly accurate and precise radiance measurements in combination with very sophisticated measurement protocols. Additionally, because F has a highly dynamic nature (compared with other vegetation information derived from spectral data) and low signal intensity, several environmental, physiological, and experimental aspects have to be considered during signal acquisition and are key for its reliable interpretation. The European Cooperation in Science and Technology (COST) Action ES1309 OPTIMISE has produced three articles addressing the main challenges in the field of F measurements. In this paper, which is the second of three, we review approaches that are available to measure F from the leaf to the canopy scale using ground-based and airborne platforms. We put specific emphasis on instrumental aspects, measurement setups, protocols, quality checks, and data processing strategies. Furthermore, we review existing techniques that account for atmospheric influences on F retrieval, address spatial scaling effects, and assess quality checks and the metadata and ancillary data required to reliably interpret retrieved F signals.
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Conover, C. A., and R. T. Poole. "Air and Soil Temperatures and Fertilizer Level Affect Growth and Quality of Epipremnum aureum Bunt." Journal of Environmental Horticulture 10, no. 3 (September 1, 1992): 156–59. http://dx.doi.org/10.24266/0738-2898-10.3.156.
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Abstract Three minimum air temperatures (AT), 15.5°, 18.5°, and 21°C (60°, 65°, and 70°F), four constant soil temperatures (ST), 15.5°, 21°, 26.5°, and 32°C (60°, 70°, 80°, and 90°F), and three fertilizer rates (FR) 2.5, 4.2, and 5.9 g 19N-2.6P-10K (0.09, 0.15, and 0.21 oz 19-6-12) Osmocote/15 cm (6 in) pot/3 months were utilized on Epipremnum aureum ‘Golden Pothos’ during November–April in 1983–84, 1984–85, and 1985–86. Data collected included plant grade, leaf color grade, top fresh weight, root fresh weight and leaf surface area. Analyzed data were similar for all three experiments with AT × ST interactions significant for 4 of 5 measurements in 1984 and 1985 and for all 5 measurements in 1986. In general, as fertilizer rate increased, all measurements increased linearly with only root fresh weight not increasing significantly. Results from the 1986 experiment are used for discussion.
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Greenberg, J. P., A. Guenther, P. Harley, L. Otter, E. M. Veenendaal, C. N. Hewitt, A. E. James, and S. M. Owen. "Eddy flux and leaf-level measurements of biogenic VOC emissions from mopane woodland of Botswana." Journal of Geophysical Research: Atmospheres 108, no. D13 (January 30, 2003): n/a. http://dx.doi.org/10.1029/2002jd002317.
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Huang, L., Z. Zhang, and X. Li. "The extrapolation of the leaf area-based transpiration of two xerophytic shrubs in a revegetated desert area in the Tengger Desert, China." Hydrology Research 46, no. 3 (March 13, 2014): 389–99. http://dx.doi.org/10.2166/nh.2014.171.
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Plant transpiration plays a key role in sand-binding zones, but obtaining accurate estimates at an integrated leaf-individual-canopy scale is difficult. In this study, transpiration rates of two typical xerophytic shrubs, Caragana korshinskii and Artemisia ordosica, were investigated during the growing season (April–October) from 2008 to 2012 in the Tengger Desert, a revegetated desert area in China. Gas exchange techniques, sap flow measurements, and the crop evapotranspiration minus micro-lysimeter method were used to evaluate plant transpiration. Transpiration data were subsequently compared with the dynamical normalized leaf area-based extrapolation. The results indicated that at leaf level, the transpiration rates of C. korshinskii and A. ordosica were 2.67 and 4.51 mmol H2O m−2s−1, respectively. The sap flow rates were 0.071 and 0.086 g h−1cm−2 at the tree level, and the transpiration rates were 0.42 and 0.35 mm d−1 at the stand level. The total seasonal transpiration of the two xerophytic shrubs reached 71.79 and 55.62 mm, representing approximately 48.4 and 37.5% of the total rainfall over this period. Direct measurements of plant transpiration and upscaling transpiration from leaf level to the stand level exhibited good correspondence, which verified that leaf area was a reliable representation of scaled transpiration, especially in arid desert regions.
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Al Salameh, Mohammed Saleh H. "Predicting leaf state effects on radiowaves based on propagation loss measurements." MATEC Web of Conferences 292 (2019): 02005. http://dx.doi.org/10.1051/matecconf/201929202005.
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A new propagation model is proposed for estimating the attenuation of wireless communication signals in woodland environments. After rainfall or snowfall, the components of the woodland area become moist which degrades the received signal level. To take this into account, the model considers wet/dry states of the foliage, and its dependency on the operating frequency. The parameters of the propagation loss model are optimized using the least squares method. To demonstrate the validity and usefulness of the model, computed results are compared with measured data where excellent matching is observed. It is noted that not only the foliage and rainfall affect the propagation phenomenon, but also wet foliage condition after rainfall contributes to the fading of the wave.
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Maréchaux, Isabelle, Megan K. Bartlett, Philippe Gaucher, Lawren Sack, and Jérôme Chave. "Causes of variation in leaf-level drought tolerance within an Amazonian forest." Journal of Plant Hydraulics 3 (January 31, 2016): e004. http://dx.doi.org/10.20870/jph.2016.e004.
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Amazonian tree communities have already been seriously impacted by extreme natural droughts, and intense droughts are predicted to increase in frequency. However, our current knowledge of Amazonian tree species’ responses to water stress remains limited, as plant trait databases include few drought tolerance traits, impeding the application and predictive power of models. Here we explored how leaf water potential at turgor loss point (πtlp), a determinant of leaf drought tolerance, varies with species life history, season, tree size and irradiance within a forest in French Guiana. First, we provided a further direct validation of a rapid method of πtlp determination based on osmometer measurements of leaf osmotic potential at full hydration for five Amazonian tree species. Next, we analysed a dataset of 131 πtlp values for a range of species, seasons, size (including saplings), and leaf exposure. We found that early-successional species had less drought-tolerant leaves than late-successional species. Species identity was the major driver of πtlp variation, whereas season, canopy tree size and leaf exposure explained little variation. Shifts in πtlp from saplings to canopy trees varied across species, and sapling leaf drought tolerance was a moderate predictor of canopy tree leaf drought tolerance. Given its low within-species variability, we propose that πtlp is a robust trait, and is useful as one index of species’ drought tolerance. We also suggest that measuring this trait would considerably advance our knowledge on leaf drought tolerance in hyperdiverse communities and would thus likely shed light on the resilience of such vulnerable species-rich ecosystem.
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Verlinden, Melanie S., Hamada AbdElgawad, Arne Ven, Lore T. Verryckt, Sebastian Wieneke, Ivan A. Janssens, and Sara Vicca. "Phosphorus stress strongly reduced plant physiological activity, but only temporarily, in a mesocosm experiment with <i>Zea mays</i> colonized by arbuscular mycorrhizal fungi." Biogeosciences 19, no. 9 (May 5, 2022): 2353–64. http://dx.doi.org/10.5194/bg-19-2353-2022.
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Abstract. Phosphorus (P) is an essential macronutrient for plant growth and one of the least available nutrients in soil. P limitation is often a major constraint for plant growth globally. Although P addition experiments have been carried out to study the long-term effects on yield, data on P addition effects on seasonal variation in leaf-level photosynthesis are scarce. Arbuscular mycorrhizal fungi (AMF) can be of major importance for plant nutrient uptake, and AMF growth may be important for explaining temporal patterns in leaf physiology. In a nitrogen (N) and P fertilization experiment with Zea mays, we investigated the effect of P limitation on leaf pigments and leaf enzymes, how these relate to leaf-level photosynthesis, and how these relationships change during the growing season. A previous study on this experiment indicated that N availability was generally high, and as a consequence, N addition did not affect plant growth, and also the leaf measurements in the current study were unaffected by N addition. Contrary to N addition, P addition strongly influenced plant growth and leaf-level measurements. At low soil P availability, leaf-level photosynthetic and respiratory activity strongly decreased, and this was associated with reduced chlorophyll and photosynthetic enzymes. Contrary to the expected increase in P stress over time following gradual soil P depletion, plant P limitation decreased over time. For most leaf-level processes, pigments and enzymes under study, the fertilization effect had even disappeared 2 months after planting. Our results point towards a key role for the AMF symbiosis and consequent increase in P uptake in explaining the vanishing P stress.
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Chen, Tingting, Ruier Zeng, Wenxuan Guo, Xueying Hou, Yubin Lan, and Lei Zhang. "Detection of Stress in Cotton (Gossypium hirsutum L.) Caused by Aphids Using Leaf Level Hyperspectral Measurements." Sensors 18, no. 9 (August 24, 2018): 2798. http://dx.doi.org/10.3390/s18092798.
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: Remote sensing can be a rapid, accurate, and simple method for assessing pest damage on plants. The objectives of this study were to identify spectral wavelengths sensitive to cotton aphid infestation. Then, the normalized difference spectral indices (NDSI) and ratio spectral indices (RSI) based on the leaf spectrum were obtained within 350–2500 nm, and their correlation with infestation were qualified. The results showed that leaf spectral reflectance decreased in the visible range (350–700 nm) and the near-infrared range (NIR, 700–1300 nm) as aphid damage severity increased, and significant differences were found in blue, green, red, NIR and short-wave infrared (SWIR) band regions between different grades of aphid damage severity. Decrease in Chlorophyll a (Chl a) pigment was more significant than that in Chlorophyll (Chl b) in the infested plants and the Chl a/b ratio showed a decreasing trend with increase in aphid damage severity. The sensitive spectral bands were mainly within NIR and SWIR ranges. The best spectral indices NDSI (R678, R1471) and RSI (R1975, R1904) were formulated with these sensitive spectral regions through reducing precise sampling method. These new indices along with 16 other stress related indices compiled from literature were further tested for their ability to detect aphid damage severity. The two indices in this study showed significantly higher coefficients of determination (R2 of 0.81 and 0.81, p < 0.01) and the least RMSE values (RMSE of 0.50 and 0.49), and hence have potential application in assessing aphid infestation severity in cotton.
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Smith, Marie-Louise, and Mary E. Martin. "A plot-based method for rapid estimation of forest canopy chemistry." Canadian Journal of Forest Research 31, no. 3 (March 1, 2001): 549–55. http://dx.doi.org/10.1139/x00-187.
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In this study we present a rapid method to scale the leaf-level chemistry of forest stands to the whole-canopy level. The method combines simple leaf-level measurements of mass and chemistry with a camera-based technique to estimate the fractional distribution of species' foliage area in a forest canopy. Results using this methodology for the estimation of whole-canopy N concentration (g/100 g) are presented and are shown to be comparable with those derived directly from litter fall collection. The ability to efficiently scale leaf-level traits to whole forest canopies enhances our ability to examine key relationships associated with these traits at various levels from the leaf to the forest stand and, with remote sensing technologies, to larger landscapes.
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Martínez-Maldonado, Fabio Ernesto, Angela María Castaño-Marín, Gerardo Antonio Góez-Vinasco, and Fabio Ricardo Marin. "Upscaling Gross Primary Production from Leaf to Canopy for Potato Crop (Solanum tuberosum L.)." Climate 10, no. 9 (August 29, 2022): 127. http://dx.doi.org/10.3390/cli10090127.
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Estimating gross primary production (GPP) is important to understand the land–atmosphere CO2 exchange for major agroecosystems. Eddy covariance (EC) measurements provide accurate and reliable information about GPP, but flux measurements are often not available. Upscaling strategies gain importance as an alternative to the limitations of the use of the EC. Although the potato provides an important agroecosystem for worldwide carbon balance, there are currently no studies on potato GPP upscaling processes. This study reports two GPP scaling-up approaches from the detailed leaf-level characterization of gas exchange of potatoes. Multilayer and big leaf approaches were applied for extrapolating chamber and biometric measurements from leaf to canopy. Measurements of leaf area index and photosynthesis were performed from planting to the end of the canopy life cycle using an LP-80 ceptometer and an IRGA Li-Cor 6800, respectively. The results were compared to concurrent measurements of surface–atmosphere GPP from the EC measurements. Big-leaf models were able to simulate the general trend of GPP during the growth cycle, but they overestimated the GPP during the maximum LAI phase. Multilayer models correctly reproduced the behavior of potato GPP and closely predicted both: the daily magnitude and half-hourly variation in GPP when compared to EC measurements. Upscaling is a reliable alternative, but a good treatment of LAI and the photosynthetic light-response curves are decisive factors to achieve better GPP estimates. The results improved the knowledge of the biophysical control in the carbon fluxes of the potato crop.
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González-Cascón, R., J. Pacheco-Labrador, and M. P. Martín. "Evolución del comportamiento espectral y la composición química en el dosel arbóreo de una dehesa." Revista de Teledetección, no. 46 (June 27, 2016): 31. http://dx.doi.org/10.4995/raet.2016.5688.
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<p>In the context of the BIOSPEC and FLUXPEC projects (http://www.lineas.cchs.csic.es/fluxpec/), spectral and biophysical variables measurements at leaf level have been conducted in the tree canopy of a holm oak dehesa (Quercus ilex) ecosystem during four vegetative periods. Measurements of bi-conical reflectance factor of intact leaf (ASD Fieldspec 3® spectroradiometer), specific leaf mass (SLM), leaf water content (LWC), nutrient (N, P, K, Ca, Mg, Mn, Fe, and Zn) and chlorophyll concentration were performed. The spectral measurements have been related with the biophysical variables by stepwise and partial least squares regression analyses. These analyses allowed to identify the spectral bands and regions that best explain the evolution of the biophysical variables and to estimate the nutrient contents during the leaf maturation process. Statistically significant estimates of the majority of the variables studied were obtained. Wavelengths that had the highest contributions explaining the chemical composition of the forest canopy were located in spectral regions of the red edge, the green visible region, and the shortwave infrared.</p>
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Bracho-Nunez, A., N. M. Knothe,, S. Welter, M. Staudt, W. R. Costa, M. A. R. Liberato, M. T. F. Piedade, and J. Kesselmeier. "Leaf level emissions of volatile organic compounds (VOC) from some Amazonian and Mediterranean plants." Biogeosciences 10, no. 9 (September 6, 2013): 5855–73. http://dx.doi.org/10.5194/bg-10-5855-2013.
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Abstract. Emission inventories defining regional and global biogenic volatile organic compounds (VOC) emission strengths are needed to determine the impact of VOC on atmospheric chemistry (oxidative capacity) and physics (secondary organic aerosol formation and effects). The aim of this work was to contribute with measurements of tree species from the poorly described tropical vegetation in direct comparison with the quite well-investigated, highly heterogeneous emissions from Mediterranean vegetation. VOC emission from sixteen plant species from the Mediterranean area were compared with twelve plant species from different environments of the Amazon basin by an emission screening at leaf level using branch enclosures. Analysis of the volatile organics was performed online by a proton-transfer-reaction mass spectrometer (PTR-MS) and offline by collection on adsorbent tubes and subsequent gas chromatographic analysis. Isoprene was the most dominant compound emitted followed by monoterpenes, methanol and acetone. The average loss rates of VOC carbon in relation to the net CO2 assimilation were found below 4% and indicating normal unstressed plant behavior. Most of the Mediterranean species emitted a large variety of monoterpenes, whereas only five tropical species were identified as monoterpene emitters exhibiting a quite conservative emission pattern (α-pinene < limonene < sabinene < ß-pinene). Mediterranean plants showed additional emissions of sesquiterpenes. In the case of Amazonian plants no sesquiterpenes were detected. However, missing of sesquiterpenes may also be due to a lack of sensitivity of the measuring systems. Furthermore, our screening activities cover only 1% of tree species of such tropical areas as estimated based on recent biodiversity reports. Methanol emissions, an indicator of growth, were found to be common in most of the tropical and Mediterranean species. A few species from both ecosystems showed acetone emissions. The observed heterogeneous emissions, including reactive VOC species which are not easily detected by flux measurements, give reason to perform more screening at leaf level and, whenever possible, within the forests under ambient conditions.
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Neinavaz, Elnaz, Andrew K. Skidmore, Roshanak Darvishzadeh, and Thomas A. Groen. "LEAF AREA INDEX RETRIEVED FROM THERMAL HYPERSPECTRAL DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B7 (June 20, 2016): 99–105. http://dx.doi.org/10.5194/isprs-archives-xli-b7-99-2016.
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Leaf area index (LAI) is an important essential biodiversity variable due to its role in many terrestrial ecosystem processes such as evapotranspiration, energy balance, and gas exchanges as well as plant growth potential. A novel approach presented here is the retrieval of LAI using thermal infrared (8–14 μm, TIR) measurements. Here, we evaluate LAI retrieval using TIR hyperspectral data. Canopy emissivity spectral measurements were recorded under controlled laboratory conditions using a MIDAC (M4401-F) illuminator Fourier Transform Infrared spectrometer for two plant species during which LAI was destructively measured. The accuracy of retrieval for LAI was then assessed using partial least square regression (PLSR) and narrow band index calculated in the form of normalized difference index from all possible combinations of wavebands. The obtained accuracy from the PLSR for LAI retrieval was relatively higher than narrow-band vegetation index (0.54 < R<sup>2</sup> < 0.74). The results demonstrated that LAI may successfully be estimated from hyperspectral thermal data. The study highlights the potential of hyperspectral thermal data for retrieval of vegetation biophysical variables at the canopy level for the first time.
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Neinavaz, Elnaz, Andrew K. Skidmore, Roshanak Darvishzadeh, and Thomas A. Groen. "LEAF AREA INDEX RETRIEVED FROM THERMAL HYPERSPECTRAL DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B7 (June 20, 2016): 99–105. http://dx.doi.org/10.5194/isprsarchives-xli-b7-99-2016.
Full textAbstract:
Leaf area index (LAI) is an important essential biodiversity variable due to its role in many terrestrial ecosystem processes such as evapotranspiration, energy balance, and gas exchanges as well as plant growth potential. A novel approach presented here is the retrieval of LAI using thermal infrared (8–14 μm, TIR) measurements. Here, we evaluate LAI retrieval using TIR hyperspectral data. Canopy emissivity spectral measurements were recorded under controlled laboratory conditions using a MIDAC (M4401-F) illuminator Fourier Transform Infrared spectrometer for two plant species during which LAI was destructively measured. The accuracy of retrieval for LAI was then assessed using partial least square regression (PLSR) and narrow band index calculated in the form of normalized difference index from all possible combinations of wavebands. The obtained accuracy from the PLSR for LAI retrieval was relatively higher than narrow-band vegetation index (0.54 < R<sup>2</sup> < 0.74). The results demonstrated that LAI may successfully be estimated from hyperspectral thermal data. The study highlights the potential of hyperspectral thermal data for retrieval of vegetation biophysical variables at the canopy level for the first time.
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Papierowska, Ewa, Jan Szatyłowicz, Stanisław Samborski, Joanna Szewińska, and Elżbieta Różańska. "The Leaf Wettability of Various Potato Cultivars." Plants 9, no. 4 (April 14, 2020): 504. http://dx.doi.org/10.3390/plants9040504.
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Leaf wettability has an impact on a plant’s ability to retain water on its leaf surface, which in turn has many environmental consequences. In the case of the potato leaf (Solanum tuberosum L.), water on the leaf surface may contribute to the development of a fungal disease. If fungal disease is caused, this may reduce the size of potato harvests, which contribute significantly to meeting global food demand. The aim of this study was to assess the leaf wettability of five potato cultivars (i.e., Bryza, Lady Claire, Rudawa, Russet Burbank, Sweet Caroline) in the context of its direct and indirect impact on potato yield. Leaf wettability was assessed on the basis of contact angle measurements using a sessile drop method with an optical goniometer. For Bryza and Rudawa cultivars, which showed, respectively, the highest and the lowest contact angle values, light microscopy as well as scanning electron microscopy analyses were performed. The results of the contact angle measurements and microscopic image analyses of the potato leaf surfaces indicated that the level of wettability was closely related to the type of trichomes on the leaf and their density. Therefore, higher resistance of the Rudawa cultivar to biotic stress conditions could be the result of the presence of two glandular trichome types (VI and VII), which produce and secrete metabolites containing various sticky and/or toxic chemicals that may poison or repel herbivores.
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Blanco, Flávio Favaro, and Marcos Vinícius Folegatti. "Estimation of leaf area for greenhouse cucumber by linear measurements under salinity and grafting." Scientia Agricola 62, no. 4 (August 2005): 305–9. http://dx.doi.org/10.1590/s0103-90162005000400001.
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The measurement of leaf area by linear parameters is a useful tool when plants cannot be destroyed for direct measurement. The objectives of this study were to establish equations to estimate the leaf area of greenhouse-cucumber and to evaluate the effects of salinity and grafting on this estimative. Non-grafted cucumber seedlings, cv. 'Hokushin', were transplanted in a greenhouse and were irrigated with water of different salinities (1.0, 3.2 and 5.0 dS m-1). In the second growing period, the same cultivar was grafted on Cucurbita spp. and the plants were irrigated with water of 1.4, 3.0 and 5.3 dS m-1. Leaves of different sizes were collected from both experiments and leaf area was determined by an integrating area meter. Leaf length (L) and width (W) were also recorded. An equation for estimating the leaf area from L and W was developed for a given salinity level or grafting condition and estimated well the area of leaves collected in the other treatments. The leaf area (LA) of cucumber 'Hokushin' could be estimated using the equation LA = 0.88LW - 4.27, for any grafting and salinity conditions.
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Hari, Pertti, Annikki Mäkelä, Frank Berninger, and Toivo Pohja. "Field evidence for the optimality hypothesis of gas exchange in plants." Functional Plant Biology 26, no. 3 (1999): 239. http://dx.doi.org/10.1071/pp98044.
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The ‘optimality hypothesis’ of gas exchange in plants has been studied since the 1970s, but testing it in the field has proven difficult. A recent reformulation of the hypothesis with detailing assumptions on leaf structure makes it possible to solve the optimisation problem explicitly, such that the predictions of gas exchange are readily testable against field data. This form of the model was tested against field measurements of photosynthesis, transpiration and stomatal conductance in Scots pine (Pinus sylvestris) shoots during three clear summer days. Model parameters were estimated independently from photosynthesis measurements on preceding days. The measurements were carried out at a new field measurement station with a very low level of noise. The predictions of photosynthesis, transpiration andstomatal conductance explained 84–98% of the variance in the data.
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Ramsay, Robbie, Chiara F. Di Marco, Mathew R. Heal, Matthias Sörgel, Paulo Artaxo, Meinrat O. Andreae, and Eiko Nemitz. "Measurement and modelling of the dynamics of NH<sub>3</sub> surface–atmosphere exchange over the Amazonian rainforest." Biogeosciences 18, no. 9 (May 6, 2021): 2809–25. http://dx.doi.org/10.5194/bg-18-2809-2021.
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Abstract. Local and regional modelling of NH3 surface exchange is required to quantify nitrogen deposition to, and emissions from, the biosphere. However, measurements and model parameterisations for many remote ecosystems – such as tropical rainforest – remain sparse. Using 1 month of hourly measurements of NH3 fluxes and meteorological parameters over a remote Amazon rainforest site (Amazon Tall Tower Observatory, ATTO), six model parameterisations based on a bidirectional, single-layer canopy compensation point resistance model were developed to simulate observations of NH3 surface exchange. Canopy resistance was linked to either relative humidity at the canopy level (RHz0′), vapour pressure deficit, or a parameter value based on leaf wetness measurements. The ratio of apoplastic NH4+ to H+ concentration, Γs, during this campaign was inferred to be 38.5 ± 15.8. The parameterisation that reproduced the observed net exchange of NH3 most accurately was the model that used a cuticular resistance (Rw) parameterisation based on leaf wetness measurements and a value of Γs=50 (Pearson correlation r=0.71). Conversely, the model that performed the worst at replicating measured NH3 fluxes used an Rw value modelled using RHz0′ and the inferred value of Γs=38.5 (r=0.45). The results indicate that a single-layer canopy compensation point model is appropriate for simulating NH3 fluxes from tropical rainforest during the Amazonian dry season and confirmed that a direct measurement of (a non-binary) leaf wetness parameter improves the ability to estimate Rw. Current inferential methods for determining Γs were noted as having difficulties in the humid conditions present at a rainforest site.
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Elings, Anne, Walter A. H. Rossing, and Wopke van der Werf. "Virtual Lesion Extension: A Measure to Quantify the Effects of Bacterial Blight on Rice Leaf CO2 Exchange." Phytopathology® 89, no. 9 (September 1999): 789–95. http://dx.doi.org/10.1094/phyto.1999.89.9.789.
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Virtual lesion extension was proposed as a measure to summarize the effects of foliar diseases with single spreading lesions on CO2-exchange parameters at the whole-leaf level. Visible lesion plus virtual lesion extension constitute a virtual lesion, in which CO2 exchange was postulated to be nil. Virtual lesion extension can be derived for each photosynthesis parameter from gas-exchange measurements. Using a leaf-shape function, one-dimensional lesion length was translated into two-dimensional lesion area, and a relationship between visible and virtual severity can be established. The model was applied to measurements of leaf CO2 exchange in rice leaves infected with Xanthomonas campestris pv. oryzae, the causal organism of rice bacterial blight. The model resulted in a virtual lesion extension of 1.1 cm for the gross CO2-exchange rate at light saturation, -3.9 cm for dark respiration rate, and 0 for initial light use efficiency. Reduced light interception due to a visible lesion caused reductions in net CO2 assimilation, and small virtual lesion extensions only marginally reduced net CO2 assimilation further. The additional reduction was smaller in case of longer leaves. Measurement of net photosynthesis rate along a transect from the base to the tip of infected leaves indicated that the location on the leaf blade where net photosynthesis decreased from normal to nil was centered around the lesion tip.
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Allen, Scott T., Margaret L. Whitsell, and Richard F. Keim. "Leaf area allometrics and morphometrics in baldcypress." Canadian Journal of Forest Research 45, no. 8 (August 2015): 963–69. http://dx.doi.org/10.1139/cjfr-2015-0039.
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Leaf area relationships are important physiologically and ecologically but are not well studied in baldcypress (Taxodium distichum (L.) Rich. var. distichum). Tree leaf area (LA) and leaf area index (LAI) were measured in a wetland in southern Louisiana by dissecting crowns of felled trees and by scaling stand-level measurements with allometry. Branchlet morphology ranged from flat and open with high specific leaf area (87.2 ± 30.7 cm2·g−1; mean ± SD) to scaled with appressed leaves and low specific leaf area (22.1 ± 11.6 cm2·g−1). Leaves were more appressed higher in the canopy. Tree LA was strongly related to sapwood basal area (SBA), and SBA was related to diameter; these allometric relationships enabled estimating LA from diameters. At the plot level, LAI estimated by allometric relationship (ranging from 1.8 to 10.2) was not linearly related to output from an optical canopy analyzer measuring light extinction; ratios of allometric to optical methods were 0.8 for the sparsest plot and 2.4 for the densest plot. LAI was less in deeper flooded plots (3.6 ± 0.6) than in transiently flooded plots (8.4 ± 0.6), but it is unclear whether this represents a difference in maximum LAI or delayed attainment of maximum LAI in lower areas.
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Lati, Ran Nisim, Sagi Filin, and Hanan Eizenberg. "Robust Methods for Measurement of Leaf-Cover Area and Biomass from Image Data." Weed Science 59, no. 2 (June 2011): 276–84. http://dx.doi.org/10.1614/ws-d-10-00054.1.
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Leaf-cover area is a widely required plant development parameter for predictive models of weed growth and competition. Its assessment is performed either manually, which is labor intensive, or via visual inspection, which provides biased results. In contrast, digital image processing enables a high level of automation, thereby offering an attractive means for estimating vegetative leaf-cover area. Nonetheless, image-driven analysis is greatly affected by illumination conditions and camera position at the time of imaging and therefore may introduce bias into the analysis. Addressing both of these factors, this paper proposes an image-based model for leaf-cover area and biomass measurements. The proposed model transforms color images into an illumination-invariant representation, thus facilitating accurate leaf-cover detection under varying light conditions. To eliminate the need for fixed camera position, images are transformed into an object–space reference frame, enabling measurement in absolute metric units. Application of the proposed model shows stability in leaf-cover detection and measurement irrespective of camera position and external illumination conditions. When tested on purple nutsedge, one of the world's most troublesome weeds, a linear relation between measured leaf-cover area and plant biomass was obtained regardless of plant developmental stage. Data on the expansion of purple nutsedge leaf-cover area is essential for modeling its spatial growth. The proposed model offers the possibility of acquiring reliable and accurate biological data from digital images without extensive photogrammetric or image-processing expertise.
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Tseng, Menq-Jiau, Cheng-lie Zhang, and Paul H. Li. "Quantitative Measurements of Mefluidide Protection of Chilled Corn Plants." Journal of the American Society for Horticultural Science 111, no. 3 (May 1986): 409–12. http://dx.doi.org/10.21273/jashs.111.3.409.
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Abstract Leaves of mefluidide-treated corn (Zea mays L.) plants showed significant protection from chilling injury compared with untreated, chilled controls. On a per-plant basis, leaves sprayed with 5, 10, 15, or 20 ppm mefluidide had 6%, 14%, 9%, or 12% damage, respectively, of the total leaf area after a 6-day exposure to 4°C, whereas controls had more than 60% damage. Treated plants had more leaf area, were taller, had greater fresh and dry weights, and flowered 6 days earlier than controls. Plant growth was stunted with a 20-ppm spray, although plants were protected from chilling injury. During a 6-day chilling period, a consistent level of about 10% electrolyte leakage was observed among treated plants, whereas from control tissue, electrolyte leakage increased from 10% to 40%. These results suggest that mefluidide may modulate the permeability of the plasma membrane in the chilling environments. Chemical name used: N-[2,4-dimethyl-5-[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide (mefluidide).
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Haefele, Stephan M., Joel D. L. C. Siopongco, Serafin T. Amarante, and To Phuc Tuong. "Effect of Abiotic Stresses on the Nondestructive Estimation of Rice Leaf Nitrogen Concentration." International Journal of Agronomy 2010 (2010): 1–11. http://dx.doi.org/10.1155/2010/863605.
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Decision support tools for non-destructive estimation of rice crop nitrogen (N) status (e.g., chlorophyll meter [SPAD] or leaf color chart [LCC]) are an established technology for improved N management in irrigated systems, but their value in rainfed environments with frequent abiotic stresses remains untested. Therefore, we studied the effect of drought, salinity, phosphorus (P) deficiency, and sulfur (S) deficiency on leaf N estimates derived from SPAD and LCC measurements in a greenhouse experiment. Linear relations between chlorophyll concentration and leaf N concentration based on dry weight (Ndw) between SPAD values adjusted for leaf thickness andNdwand between LCC scores adjusted for leaf thickness andNdwcould be confirmed for all treatments and varieties used. Leaf spectral reflectance measurements did not show a stress-dependent change in the reflectance pattern, indicating that no specific element of the photosynthetic complex was affected by the stresses and at the stress level applied. We concluded that SPAD and LCC are potentially useful tools for improved N management in moderately unfavorable rice environments. However, calibration for the most common rice varieties in the target region is recommended to increase the precision of the leaf N estimates.
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Tasnim, Rafa, and Yong-Jiang Zhang. "Are Wild Blueberries a Crop with Low Photosynthetic Capacity? Chamber-Size Effects in Measuring Photosynthesis." Agronomy 11, no. 8 (August 6, 2021): 1572. http://dx.doi.org/10.3390/agronomy11081572.
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Wild lowbush blueberries, an important fruit crop native to North America, contribute significantly to the economy of Maine, USA, Atlantic Canada, and Quebec. However, its photosynthetic capacity has not been well-quantified, with only a few studies showing its low photosynthetic rates. Its small leaves make accurate leaf-level photosynthetic measurements difficult and introduce potential uncertainties in using large leaf chambers. Here, we determined the photosynthetic rate for five different wild blueberry genotypes using a big leaf chamber enclosing multiple leaves and a small leaf chamber with a single leaf to test whether using big leaf chambers (branch-level measurements) underestimates the photosynthetic capacity. Photosynthetic rates of wild blueberries were significantly (35–47%) lower when using the big leaf chamber, and they are not a crop with low photosynthetic capacity, which can be as high as 16 μmol m−2 s−1. Additionally, wild blueberry leaves enclosed in the big chamber at different positions of a branch did not differ in chlorophyll content and photosynthetic rate, suggesting that the difference was not caused by variation among leaves but probably due to leaf orientations and self-shading in the big chamber. A significant linear relationship between the photosynthetic rate measured by the small and big leaf chambers suggests that the underestimation in leaf photosynthetic capacity could be corrected. Therefore, chamber-size effects need to be considered in quantifying photosynthetic capacity for small-leaf crops, and our study provided important guidelines for future photosynthesis research. We also established the relationship between the Electron Transport Rate (ETR) and photosynthetic CO2 assimilation for wild blueberries. ETR provides an alternative to quantify photosynthesis, but the correlation coefficient of the relationship (R2 = 0.65) suggests that caution is needed in this case.
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Li, Ji, Yongguang Zhang, Lianhong Gu, Zhaohui Li, Jing Li, Qian Zhang, Zhaoying Zhang, and Lian Song. "Seasonal variations in the relationship between sun-induced chlorophyll fluorescence and photosynthetic capacity from the leaf to canopy level in a rice crop." Journal of Experimental Botany 71, no. 22 (September 9, 2020): 7179–97. http://dx.doi.org/10.1093/jxb/eraa408.
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Abstract Photosynthetic capacity (leaf maximum carboxylation rate, Vcmax) is a critical parameter for accurately assessing carbon assimilation by plant canopies. Recent studies of sun-induced chlorophyll fluorescence (SIF) have shown potential for estimating Vcmax at the ecosystem level. However, the relationship between SIF and Vcmax at the leaf and canopy levels is still poorly understood. In this study, we investigated the dynamic relationship between SIF and Vcmax and its controlling factors using SIF and CO2 response measurements in a rice paddy. We found that SIF and its yield (SIFy) were strongly correlated with Vcmax during the growing season, although the relationship varied with plant growth stages. After flowering, SIFy showed a stronger relationship with Vcmax than SIF flux at both the leaf and canopy levels. Further analysis suggested that the divergence of the link between SIF and Vcmax from leaf to canopy are the result of changes in canopy structure and leaf physiology, highlighting that these need to be considered when interpreting the SIF signal across spatial scales. Our results provide evidence that remotely sensed SIF observations can be used to track seasonal variations in Vcmax at the leaf and canopy levels.
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Hakala, T., O. Nevalainen, S. Kaasalainen, and R. Mäkipää. "Technical Note: Hyperspectral lidar time series of pine canopy physiological parameters." Biogeosciences Discussions 11, no. 10 (October 23, 2014): 15019–35. http://dx.doi.org/10.5194/bgd-11-15019-2014.
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Abstract. We present an empirical application of hyperspectral lidar for monitoring the seasonal and spatial changes in pine chlorophyll content and upscaling the accurate leaf-level chlorophyll measurements into branch and tree level. The results show the capability of the new instrument for monitoring the changes in the shape and physiology of tree canopy: the spectral indices retrieved from the hyperspectral point cloud agree with laboratory measurements of the chlorophyll content. The approach opens new prospects for replacing destructive and labor-intensive manual sampling with remote observations of tree physiology.
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Botha, E. J., B. J. Zebarth, and B. Leblon. "Non-destructive estimation of potato leaf chlorophyll and protein contents from hyperspectral measurements using the PROSPECT radiative transfer model." Canadian Journal of Plant Science 86, no. 1 (January 1, 2006): 279–91. http://dx.doi.org/10.4141/p05-017.
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Optimizing nitrogen (N) fertilization in potato (Solanum tuberosum L.) production by in-season measurements of potato N status may improve fertilizer N-use efficiency. Hyperspectral leaf reflectance and transmittance measurements can be used to assess potato N status by estimating leaf chlorophyll or N contents. This study evaluated the ability of the inverted PROSPECT radiative transfer model to predict leaf chlorophyll and N (as protein) contents. Trials were conducted with Russet Burbank and Shepody potato cultivars under different N fertility rates (0 to 300 kg N ha-1) in 2001 and 2002. Leaf reflectance and transmittance, leaf chlorophyll content, and leaf protein content were measured. Leaf chlorophyll and protein content correlated significantly (r = 0.16*, n = 584), but the relationship was strongly dependent on sampling date (r = 0.55* to 0.92*). Chlorophyll content was predicted with reasonable accuracy by the model, particularly in 2002. The low estimation accuracy in 2001 was probably related to sample variability induced by prolonged drought conditions. Protein content could not be predicted with any degree of accuracy by the model. The relative success of the PROSPECT model to predict chlorophyll content, and the good correlation between leaf chlorophyll and leaf N, suggests that it might be used as a component of a more complex leaf-canopy reflectance model to estimate chlorophyll content from reflectance spectra at the canopy level. Key words: Leaf reflectance, PROSPECT radiative transfer model, Solanum tuberosum
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Yiğit, Nurcan, Mehmet Çetin, and Hakan Şevik. "Prunus laurocerasus L. Türü Bazı Yaprak Mikromorfolojik Karakterlerinin Yetişme Ortamına Göre Değişimi." Turkish Journal of Agriculture - Food Science and Technology 6, no. 11 (October 28, 2018): 1517. http://dx.doi.org/10.24925/turjaf.v6i11.1517-1521.1704.
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In this study, it was aimed to identify the change in some micromorphological characters in Prunus laurocerasus L. leaves obtained from 6 different provinces located in the areas where different climate types are dominant, depending on their habitat. In this regard, the leaf samples were collected from Prunus laurocerasus L. individuals in the provinces of Rize, Samsun located in the areas including the European-Siberian, Irano-Turanian and Mediterranean phytogeographical regions. The leaf epidermis images were obtained with the help of SEM on the collected leaf samples, and the required measurement procedures were performed on these images with the help of “Image J” measurement program. By measurements performed on the leaf epidermis surface, Stoma Length (µm), Stoma Width (µm), Pore length (µm), Pore width (µm) and Stoma Density (in an area of 1 mm2) measured such as micromorphological characters. The data obtained were subjected to the Variance analysis and Duncan’s test, and the change in these characters depending on their habitat was statistically evaluated. At the end of the study, it was determined that there were statistically significant differences at the confidence level of minimum 95% among the conditions of the habitat in terms of all characters except for the stomatal width.
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Yang, Peiqi, Christiaan van der Tol, Petya K. E. Campbell, and Elizabeth M. Middleton. "Unraveling the physical and physiological basis for the solar- induced chlorophyll fluorescence and photosynthesis relationship using continuous leaf and canopy measurements of a corn crop." Biogeosciences 18, no. 2 (January 20, 2021): 441–65. http://dx.doi.org/10.5194/bg-18-441-2021.
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Abstract. Estimates of the gross terrestrial carbon uptake exhibit large uncertainties. Sun-induced chlorophyll fluorescence (SIF) has an apparent near-linear relationship with gross primary production (GPP). This relationship will potentially facilitate the monitoring of photosynthesis from space. However, the exact mechanistic connection between SIF and GPP is still not clear. To explore the physical and physiological basis for their relationship, we used a unique data set comprising continuous field measurements of leaf and canopy fluorescence and photosynthesis of corn over a growing season. We found that, at canopy scale, the positive relationship between SIF and GPP was dominated by absorbed photosynthetically active radiation (APAR), which was equally affected by variations in incoming radiation and changes in canopy structure. After statistically controlling these underlying physical effects, the remaining correlation between far-red SIF and GPP due solely to the functional link between fluorescence and photosynthesis at the photochemical level was much weaker (ρ=0.30). Active leaf level fluorescence measurements revealed a moderate positive correlation between the efficiencies of fluorescence emission and photochemistry for sunlit leaves in well-illuminated conditions but a weak negative correlation in the low-light condition, which was negligible for shaded leaves. Differentiating sunlit and shaded leaves in the light use efficiency (LUE) models for SIF and GPP facilitates a better understanding of the SIF–GPP relationship at different environmental and canopy conditions. Leaf level fluorescence measurements also demonstrated that the sustained thermal dissipation efficiency dominated the seasonal energy partitioning, while the reversible heat dissipation dominated the diurnal leaf energy partitioning. These diurnal and seasonal variations in heat dissipation underlie, and are thus responsible for, the observed remote-sensing-based link between far-red SIF and GPP.
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Ma, Dongdong, Liangju Wang, Libo Zhang, Zhihang Song, Tanzeel U. Rehman, and Jian Jin. "Stress Distribution Analysis on Hyperspectral Corn Leaf Images for Improved Phenotyping Quality." Sensors 20, no. 13 (June 30, 2020): 3659. http://dx.doi.org/10.3390/s20133659.
Full textAbstract:
High-throughput imaging technologies have been developing rapidly for agricultural plant phenotyping purposes. With most of the current crop plant image processing algorithms, the plant canopy pixels are segmented from the images, and the averaged spectrum across the whole canopy is calculated in order to predict the plant’s physiological features. However, the nutrients and stress levels vary significantly across the canopy. For example, it is common to have several times of difference among Soil Plant Analysis Development (SPAD) chlorophyll meter readings of chlorophyll content at different positions on the same leaf. The current plant image processing algorithms cannot provide satisfactory plant measurement quality, as the averaged color cannot characterize the different leaf parts. Meanwhile, the nutrients and stress distribution patterns contain unique features which might provide valuable signals for phenotyping. There is great potential to develop a finer level of image processing algorithm which analyzes the nutrients and stress distributions across the leaf for improved quality of phenotyping measurements. In this paper, a new leaf image processing algorithm based on Random Forest and leaf region rescaling was developed in order to analyze the distribution patterns on the corn leaf. The normalized difference vegetation index (NDVI) was used as an example to demonstrate the improvements of the new algorithm in differentiating between different nitrogen stress levels. With the Random Forest method integrated into the algorithm, the distribution patterns along the corn leaf’s mid-rib direction were successfully modeled and utilized for improved phenotyping quality. The algorithm was tested in a field corn plant phenotyping assay with different genotypes and nitrogen treatments. Compared with the traditional image processing algorithms which average the NDVI (for example) throughout the whole leaf, the new algorithm more clearly differentiates the leaves from different nitrogen treatments and genotypes. We expect that, besides NDVI, the new distribution analysis algorithm could improve the quality of other plant feature measurements in similar ways.
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Bauerle, William L., William W. Inman, and Jerry B. Dudley. "Leaf Abscisic Acid Accumulation in Response To Substrate Water Content: Linking Leaf Gas Exchange Regulation with Leaf Abscisic Acid Concentration." Journal of the American Society for Horticultural Science 131, no. 2 (March 2006): 295–301. http://dx.doi.org/10.21273/jashs.131.2.295.
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Quantitative differences in leaf abscisic acid (ABAL) among four cultivars of red maple (Acer rubrum L.) and one freeman maple (Acer ×freemanii E. Murray) cultivar were investigated. This study tested the hypothesis that ABAL concentration can be used to compare the effects of water stress on the gas exchange response of five different maple genotypes, including four red maple cultivars [`Summer Red', `October Glory', `Autumn Flame', and `Franksred' ('Red Sunset')] and one hybridized freeman maple cultivar ['Jeffersred' ('Autumn Blaze')]. Two-year-old cloned genotypes of red maple and freeman maple were subjected to two treatments: irrigated daily to container capacity or irrigation withheld for one drought and recovery cycle. Leaf abscisic acid concentration, gas exchange, and wholetree sap flow measurements were conducted under well-watered and drought stress conditions. Over the course of the drought stress and recovery phase, net photosynthesis (Anet), stomatal conductance (gs), and transpiration (E) declined as ABAL and instantaneous water use efficiency (A/gs) increased. Until severe water stress conditions were prominent, water use was higher in `Summer Red' as compared to `October Glory'. This study found that ABAL tracked gs and that stomatal responsiveness to substrate moisture deficit is likely mediated by ABA accumulation in leaf tissue. This research demonstrates a leaf level physiological response to substrate volumetric water content that appears to depend on ABAL concentration. In addition, the evidence in this study indicates that ABAL may be used as a potential surrogate for the gs response to substrate water stress and could become part of a cultivar drought tolerance selection strategy for red maple and freeman maple.
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Collatz, GJ, M. Ribas-Carbo, and JA Berry. "Coupled Photosynthesis-Stomatal Conductance Model for Leaves of C4 Plants." Functional Plant Biology 19, no. 5 (1992): 519. http://dx.doi.org/10.1071/pp9920519.
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Leaf based models of net photosynthesis (An) and stomatal conductance (g) are often components of whole plant, canopy and regional models of net primary productivity and surface energy balance. Since C4 metabolism shows unique responses to environmental conditions and C4 species are important agriculturally and ecologically, a realistic and accurate leaf model specific to C4 plants is needed. In this paper we develop a simple model for predicting An and g from leaves of C4 plants that is easily parameterised and that predicts many of the important environmental responses. We derive the leaf model from a simple biochemical-intercellular transport model of C4 photosynthesis that includes inorganic carbon fixation by PEP carboxylase, light dependent generation of PEP and RuBP, rubisco reaction kinetics, and the diffusion of inorganic carbon and O2 between the bundle sheath and mesophyll. We argue that under most conditions these processes can be described simply as three potentially limiting steps. The leaf photosynthesis model treats An as first order with respect to either light, CO2 or the amount of rubisco present and produces a continuous transition between limitations. The independent variables of the leaf photosynthesis model are leaf temperature (TI), intercellular CO2 levels and the absorbed quantum flux. A simple linear model of g in terms of An and leaf surface CO2 level (ps) and relative humidity (hs) is combined with the photosynthesis model to give leaf photosynthesis as a function of absorbed quantum flux, T1 and ps and hs levels. Gas exchange measurements from corn leaves exposed to varied light, CO2 and temperature levels are used to parameterise and test the models. Model parameters are determined by fitting the models to a set of 21 measurements. The behaviour of the models is compared with an independent set of 71 measurements, and the predictions are shown to be highly correlated with the data. Under most conditions the leaf model can be parameterised simply by determining the level of rubisco in the leaves. The effects of light environment, nutritional status and water stress levels on An and g can be accounted for by appropriate adjustment of the capacity for rubisco to fix CO2. We estimate rubsico capacity from CO2 and light saturated photosynthesis although leaf nitrogen content or rubisco assays from leaf extracts could also be used for this purpose.
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Egea, Gregorio, Ian C. Dodd, María M. González-Real, Rafael Domingo, and Alain Baille. "Partial rootzone drying improves almond tree leaf-level water use efficiency and afternoon water status compared with regulated deficit irrigation." Functional Plant Biology 38, no. 5 (2011): 372. http://dx.doi.org/10.1071/fp10247.
Full textAbstract:
To determine whether partial rootzone drying (PRD) optimised leaf gas exchange and soil–plant water relations in almond (Prunus dulcis (Mill.) D.A. Webb) compared with regulated deficit irrigation (RDI), a 2 year trial was conducted on field-grown trees in a semiarid climate. Five irrigation treatments were established: full irrigation (FI) where the trees were irrigated at 100% of the standard crop evapotranspiration (ETc); three PRD treatments (PRD70, PRD50 and PRD30) that applied 70, 50 and 30% ETc, respectively; and a commercially practiced RDI treatment that applied 50% ETc during the kernel-filling stage and 100% ETc during the remainder of the growth season. Measurements of volumetric soil moisture content in the soil profile (0–100 cm), predawn leaf water potential (Ψpd), midday stem water potential (Ψms), midday leaf gas exchange and trunk diameter fluctuations (TDF) were made during two growing seasons. The diurnal patterns of leaf gas exchange and stem water potential (Ψs) were appraised during the kernel-filling stage in all irrigation regimes. When tree water relations were assessed at solar noon, PRD did not show differences in either leaf gas exchange or tree water status compared with RDI. At similar average soil moisture status (adjudged by similar Ψpd), PRD50 trees had higher water status than RDI trees in the afternoon, as confirmed by Ψs and TDF. Although irrigation placement showed no effects on diurnal stomatal regulation, diurnal leaf net photosynthesis (Al) was substantially less limited in PRD50 than in RDI trees, indicating that PRD improved leaf-level water use efficiency.
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Hakala, T., O. Nevalainen, S. Kaasalainen, and R. Mäkipää. "Technical Note: Multispectral lidar time series of pine canopy chlorophyll content." Biogeosciences 12, no. 5 (March 12, 2015): 1629–34. http://dx.doi.org/10.5194/bg-12-1629-2015.
Full textAbstract:
Abstract. We present an empirical application of multispectral laser scanning for monitoring the seasonal and spatial changes in pine chlorophyll (a + b) content and upscaling the accurate leaf-level chlorophyll measurements into branch and tree level. The results show the capability of the new instrument for monitoring the changes in the shape and physiology of tree canopy: the spectral indices retrieved from the multispectral point cloud agree with laboratory measurements of the chlorophyll a and b content. The approach opens new prospects for replacing destructive and labour-intensive manual sampling with remote observations of tree physiology.
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El-Gioushy, Sherif Fathy, Rokayya Sami, Amina A. M. Al-Mushhin, Hanan M. Abou El-Ghit, Mohamed S. Gawish, Khadiga Ahmed Ismail, and Reda M. Y. Zewail. "Foliar Application of ZnSO4 and CuSO4 Affects the Growth, Productivity, and Fruit Quality of Washington Navel Orange Trees (Citrus sinensis L.) Osbeck." Horticulturae 7, no. 8 (August 9, 2021): 233. http://dx.doi.org/10.3390/horticulturae7080233.
Full textAbstract:
The goal of this study was to examine how to improve the vegetative growth, nutritional status, productivity, and fruit quality of Washington navel orange trees by examining the effect of foliar application of ZnSO4 (0, 300, and 600 mg/L) solutions in combination with CuSO4 (0, 200, and 400 mg/L) solutions on Washington navel orange trees, which were 11 years old and grown in clay loam soil with a surface irrigation system. The results showed that all the investigated measurements responded specifically to each investigated factor. ZnSO4 elicited a stronger and more effective response than CuSO4. Nonetheless, the response varied only slightly or moderately from one measurement to the next. In terms of the interaction effect between ZnSO4 and CuSO4 concentrations, the effect of each investigated factor was directly reflected in its combinations, with ZnSO4 (600 mg/L) and CuSO4 (200 and 400 mg/L) being the most effective for the majority of the measurements under consideration. When the highest level of ZnSO4 was combined with the highest level of CuSO4, the highest values for the various vegetative growth parameters shoot length and diameter, number of leaves per shoot, leaf area, and total assimilation area per shoot were obtained. As a result, the nutritional status (the highest total leaf chlorophyll and leaf mineral contents) was significantly coupled with the treatment of 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4. Moreover, the combinations of the highest ZnSO4 concentration (600 mg/L) and CuSO4 concentration (400 mg/L) exhibited the greatest statistical values of the measurements of fruiting aspects as well as fruit quality. Consequently, it can be recommended that using 600 mg/L ZnSO4 in combination with 400 mg/L CuSO4 as a foliar spray on monthly basis during the period from March to July could be safely recommended under similar environmental conditions and horticulture practices adopted in the present experiment.
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Neves, Ademir D., Ricardo F. Oliveira, and José R. P. Parra. "A new concept for insect damage evaluation based on plant physiological variables." Anais da Academia Brasileira de Ciências 78, no. 4 (December 2006): 821–35. http://dx.doi.org/10.1590/s0001-37652006000400015.
Full textAbstract:
The objective of this study was to determine the damage levels caused by Orthezia praelonga Douglas, 1891 and Leucoptera coffeella (Guérin-Mèneville 1842), on rangpur lime and Obatã coffee leaves, respectively. Measurements were based on a new concept for the evaluation of the following plant physiological parameters: photosynthesis, stomatal conductance, leaf temperature and transpiration, and internal concentration of CO2 (by infrared analyzer). A negative correlation between infestation level and photosynthesis was found, where the negative inflexion point of the curve was considered as a reference for damage levels. The control level for O. praelonga is below the 7-13% limit for damaged leaf area (40 to 70 scales per leaf), while for L. coffeella it is below the 26-36% limit for the same variable. Photosynthesis provided the best correlation for this type of analysis.
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Potůčková, Markéta, Lucie Červená, Lucie Kupková, Zuzana Lhotáková, and Jana Albrechtová. "Statistical comparison of spectral and biochemical measurements on an example of Norway spruce stands in the Ore Mountains, Czech Republic." Geoinformatics FCE CTU 15, no. 1 (July 22, 2016): 69–83. http://dx.doi.org/10.14311/gi.15.1.6.
Full textAbstract:
The physiological status of vegetation and changes thereto can be monitored by means of biochemical analysis of collected samples as well as by means of spectroscopic measurements either on the leaf level, using field (or laboratory) spectroradiometers or on the canopy level, applying hyperspectral airborne or spaceborne image data. The presented study focuses on the statistical comparison and ascertainment of relations between three datasets collected from selected Norway spruce forest stands in the Ore Mountains, Czechia. The data sets comprise i) photosynthetic pigments (chlorophylls, carotenoids) and water content of 495 samples collected from 55 trees from three different vertical levels and the first three needle age classes, ii) the spectral reflectance of the same samples measured with an ASD Field Spec 4 Wide-Res spectroradiometer equipped with a plant contact probe, iii) an airborne hyperspecral image acquired with an Apex sensor. The datasets cover two localities in the Ore Mountains that were affected differently by acid deposits in the 1970s and 1980s. A one-way analysis of variance (ANOVA), Tukey’s honest significance test, hot spot analysis and linear regression were applied either on the original measurements (the content of leaf compounds and reflectance spectra) or derived values, i.e., selected spectral indices. The results revealed a generally low correlation between the photosynthetic pigments, water content and spectral measurement. The results of the ANOVA showed significant differences between sites (model areas) only in the case of the leaf compound dataset. Differences between the stands on various levels of significance exist in all three datasets and are explained in detail. The study also proved that the vertical gradient of the biochemical and biophysical parameters in the canopy play a role when the optical properties of the forest stands are modelled.