Artykuły w czasopismach na temat „Estimation de la surface foliaire”
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1
Ruget, F., R. Bonhomme i M. Chartier. "Estimation simple de la surface foliaire de plantes de maïs en croissance". Agronomie 16, nr 9 (1996): 553–62. http://dx.doi.org/10.1051/agro:19960903.
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Cregg, Bert M. "Leaf Area Estimation of Mature Foliage of Juniperus". Forest Science 38, nr 1 (1.02.1992): 61–67. http://dx.doi.org/10.1093/forestscience/38.1.61.
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Abstract The ratio of total surface area to projected leaf area was determined for mature foliage samples collected at three canopy heights from Juniperus virginiana and J. scopulorum from four seed sources grown in southeastern Nebraska. The relation of projected leaf area to leaf dry weight and volume was also determined. Total surface area was estimated to be 3.2 times the projected surface area. This relationship was independent of seed source or crown position. Projected leaf area can be satisfactorily estimated from weight or volume. However, these relationships differed by crown position or seed source. These results indicate that leaf area of mature juniper foliage may be rapidly estimated through measurement of projected surface area. Further, the leaf area of large samples may be estimated by determining the appropriate specific leaf area or surface-to-volume ratios. For. Sci. 38(1):61-67.
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Palacin, Jordi, Tomas Palleja, Marcel Tresanchez, Ricardo Sanz, Jordi Llorens, Manel Ribes-Dasi, Joan Masip, Jaume Arno, Alexandre Escola i Joan Ramon Rosell. "Real-Time Tree-Foliage Surface Estimation Using a Ground Laser Scanner". IEEE Transactions on Instrumentation and Measurement 56, nr 4 (sierpień 2007): 1377–83. http://dx.doi.org/10.1109/tim.2007.900126.
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Zeide, Boris, i Peter Pfeifer. "A Method for Estimation of Fractal Dimension of Tree Crowns". Forest Science 37, nr 5 (1.11.1991): 1253–65. http://dx.doi.org/10.1093/forestscience/37.5.1253.
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Abstract A method is proposed for estimating fractal dimension of tree crowns from measurements of foliage mass and crown volume. Because fractal dimensions for each of the ten investigated species were greater than two, crown surface and volume depend on the unit of measurement. The power relationship between foliage mass and crown volume reflects self-similarity of tree crowns. In all studied cases, fractal dimensions of dominant trees were greater than those of intermediate trees of the same species. Fractal dimension can be used as an indicator of tolerance, crown class, and foliage distribution within a crown. For. Sci. 37(5):1253-1265.
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Lin, C., S. C. Popescu, S. C. Huang, Y. C. Chen, P. T. Chang i H. L. Wen. "A novel reflectance-based model for evaluating chlorophyll concentration of fresh and water-stressed leaves". Biogeosciences Discussions 10, nr 11 (18.11.2013): 17893–937. http://dx.doi.org/10.5194/bgd-10-17893-2013.
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Abstract. Water deficit can cause chlorophyll degradation which decreases foliar chlorophyll concentration (Chls). Few studies investigated the effectiveness of spectral indices under water stress conditions. Chlorophyll meters have been extensively used for a wide variety of leaf chlorophyll and nitrogen estimations. Since a chlorophyll meter works based on the sensing of leaves absorptance and transmittance, the reading of chlorophyll concentration will be affected by changes in transmittance as if there is a water deficit in leaves. The overall objective of this paper was to develop a novel and reliable reflectance-based model for estimating Chls of fresh and water stressed leaves using the reflectance at the absorption bands of chlorophyll a and b and the red edge spectrum. Three independent experiments were designed to collect data from three leaf sample sets for the construction and validation of Chls estimation models. First, a reflectance experiment was conducted to collect foliar Chls and reflectance of leaves with varying water stress using the ASD FieldSpec spectroradiometer. Second, a chlorophyll meter (SPAD-502) experiment was carried out to collect foliar Chls and meter reading. These two datasets were separately used for developing reflectance-based or absorptance-based Chls estimation models using linear and nonlinear regression analysis. Suitable models were suggested mainly based on the coefficient of determination (R2). Finally, an experiment was conducted to collect the third dataset for the validation of Chls models using the root mean squared error (RMSE) and the mean absolute error (MAE). In all of the experiments, the observations (real values) of the foliar Chls were extracted from acetone solution and determined by using a Hitachi U-2000 spectrophotometer. The spectral indices in the form of reflectance ratio/difference/slope derived from the chlb absorption bands (ρ645 and ρ455) provided Chls estimates with RMSE around 0.40–0.55 mg g–1 for both fresh and water-stressed samples. We improved Chls prediction accuracy by incorporating the reflectance at red edge position (ρREP) in regression models. An effective chlorophyll indicator with the form of (ρ645–ρ455) / ρREP proved to be the most accurate and stable predictor for foliar Chls concentration. This model was derived with an R2 of 0.90 (P < 0.01) from the training samples and evaluated with RMSE 0.35 and 0.38 mg g–1 for the validation samples of fresh and water stressed leaves, respectively. The average prediction error was within 14% of the mean absolute error.
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Régnière, Jacques, i Chris Sanders. "Abundance and Distribution of Foliage on Balsam Fir and White Spruce in Reference to Spruce Budworm Ecology and Absolute Population Density Estimation". Forests 13, nr 4 (30.03.2022): 534. http://dx.doi.org/10.3390/f13040534.
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We describe the distribution and amount of foliage, expressed as foliated branch surface area, weight, or number of buds in the live crown of healthy open-grown and closed-canopy balsam fir and white spruce trees. Balsam fir and white spruce have very similar total foliage surface area and weight. The live crown of white spruce trees contains fewer buds than balsam fir of similar dimensions. Thus, bud density per unit foliage weight or surface area is higher in balsam fir than in white spruce. We also observed that buds tend to grow in clusters more often on balsam fir than on white spruce, and that larvae of the spruce budworm preferentially attack buds that grow in clusters. Equations were developed to predict the total surface area and weight of foliage as well as number of buds in the live crown for estimation of absolute population density of spruce budworm. These equations use diameter at breast height (DBH) and the number of nodes in the live crown as predictors. When data on the number of live nodes are unavailable, it can be estimated from tree height. Equations were also developed from which to estimate foliage area, weight or bud numbers from DBH only.
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Lin, C., S. C. Popescu, S. C. Huang, P. T. Chang i H. L. Wen. "A novel reflectance-based model for evaluating chlorophyll concentrations of fresh and water-stressed leaves". Biogeosciences 12, nr 1 (6.01.2015): 49–66. http://dx.doi.org/10.5194/bg-12-49-2015.
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Abstract. Water deficits can cause chlorophyll degradation which decreases the total concentration of chlorophyll a and b (Chls). Few studies have investigated the effectiveness of spectral indices under water-stressed conditions. Chlorophyll meters have been extensively used for a wide variety of leaf chlorophyll and nitrogen estimations. Since a chlorophyll meter works by sensing leaves absorptance and transmittance, the reading of chlorophyll concentration will be affected by changes in transmittance as if there were a water deficit in the leaves. The overall objective of this paper was to develop a novel and reliable reflectance-based model for estimating Chls of fresh and water-stressed leaves using the reflectance at the absorption bands of chlorophyll a and b and the red edge spectrum. Three independent experiments were designed to collect data from three leaf sample sets for the construction and validation of Chls estimation models. First, a reflectance experiment was conducted to collect foliar Chls and reflectance of leaves with varying water stress using the ASD FieldSpec spectroradiometer. Second, a chlorophyll meter (SPAD-502) experiment was carried out to collect foliar Chls and meter readings. These two data sets were separately used for developing reflectance-based or absorptance-based Chls estimation models using linear and nonlinear regression analysis. Suitable models were suggested mainly based on the coefficient of determination (R2). Finally, an experiment was conducted to collect the third data set for the validation of Chls models using the root mean squared error (RMSE) and the mean absolute error (MAE). In all of the experiments, the observations (real values) of the foliar Chls were extracted from acetone solution and determined by using a Hitachi U-2000 spectrophotometer. The spectral indices in the form of reflectance ratio/difference/slope derived from the Chl b absorption bands (ρ645 and ρ455) provided Chls estimates with RMSE around 0.40–0.55 mg g−1 for both fresh and water-stressed samples. We improved Chls prediction accuracy by incorporating the reflectance at red edge position (ρREP) in regression models. An effective chlorophyll indicator with the form of (ρ645–ρ455)/ρREP proved to be the most accurate and stable predictor for foliar Chls concentration. This model was derived with an R2 of 0.90 (P < 0.01) from the training samples and evaluated with RMSE 0.35 and 0.38 mg g−1 for the validation samples of fresh and water-stressed leaves, respectively. The average prediction error was within 14% of the mean absolute error.
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Lhomme, J. P., N. Boudhina, M. M. Masmoudi i A. Chehbouni. "Estimation of crop water requirements: extending the one-step approach to dual crop coefficients". Hydrology and Earth System Sciences 19, nr 7 (30.07.2015): 3287–99. http://dx.doi.org/10.5194/hess-19-3287-2015.
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Abstract. Crop water requirements are commonly estimated with the FAO-56 methodology based upon a two-step approach: first a reference evapotranspiration (ET0) is calculated from weather variables with the Penman–Monteith equation, then ET0 is multiplied by a tabulated crop-specific coefficient (Kc) to determine the water requirement (ETc) of a given crop under standard conditions. This method has been challenged to the benefit of a one-step approach, where crop evapotranspiration is directly calculated from a Penman–Monteith equation, its surface resistance replacing the crop coefficient. Whereas the transformation of the two-step approach into a one-step approach has been well documented when a single crop coefficient (Kc) is used, the case of dual crop coefficients (Kcb for the crop and Ke for the soil) has not been treated yet. The present paper examines this specific case. Using a full two-layer model as a reference, it is shown that the FAO-56 dual crop coefficient approach can be translated into a one-step approach based upon a modified combination equation. This equation has the basic form of the Penman–Monteith equation but its surface resistance is calculated as the parallel sum of a foliage resistance (replacing Kcb) and a soil surface resistance (replacing Ke). We also show that the foliage resistance, which depends on leaf stomatal resistance and leaf area, can be inferred from the basal crop coefficient (Kcb) in a way similar to the Matt–Shuttleworth method.
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Lhomme, J. P., N. Boudhina, M. M. Masmoudi i A. Chehbouni. "Estimation of crop water requirements: extending the one-step approach to dual crop coefficients". Hydrology and Earth System Sciences Discussions 12, nr 5 (13.05.2015): 4933–63. http://dx.doi.org/10.5194/hessd-12-4933-2015.
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Abstract. Crop water requirements are commonly estimated with the FAO-56 methodology based upon a "two-step" approach: first a reference evapotranspiration (ET0) is calculated from weather variables with the Penman–Monteith equation; then ET0 is multiplied by a tabulated crop-specific coefficient (Kc) to determine the water requirement (ETc) of a given crop under standard conditions. This method has been challenged to the benefit of a "one-step" approach, where crop evapotranspiration is directly calculated from a Penman–Monteith equation, its surface resistance replacing the crop coefficient. Whereas the transformation of the two-step approach into a one-step approach has been well documented when a single crop coefficient (Kc) is used, the case of dual crop coefficients (Kcb for the crop and Ke for the soil) has not been treated yet. The present paper examines this specific case. Using a full two-layer model as a reference, it is shown that the FAO-56 dual crop coefficient approach can be translated into a one-step approach based upon a modified combination equation. This equation has the basic form of the Penman–Monteith equation, but its surface resistance is calculated as the parallel sum of a foliage resistance (replacing Kcb) and a soil surface resistance (replacing Ke). We also show that the foliage resistance, which depends on leaf stomatal resistance and leaf area, can be inferred from the basal crop coefficient (Kcb) in a way similar to the Matt–Shuttleworth method.
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Brand, David G. "Estimating the surface area of spruce and pine foliage from displaced volume and length". Canadian Journal of Forest Research 17, nr 10 (1.10.1987): 1305–8. http://dx.doi.org/10.1139/x87-203.
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Accurate determination of the surface area of needle-leaved trees is a basic requirement for many types of physiological or growth analysis studies in forest research. While many methods are available to estimate surface area, there is still a need for an accurate, rapid measurement technique for species with three- or four-sided needle morphology. I propose a regression technique with length and displaced volume as the independent variables. The regression technique is an improvement over the use of displaced volume and length in direct geometric calculation as it does not assume a constant needle morphology. The regression technique gives more accurate results than direct calculation, is comparable in precision, and is necessary to counter bias where variation in the cross-sectional shape of foliage is related to the treatment or variable under study. Use of regression, however, requires that a subsample of foliage, representing the range of conditions to be studied, be sectioned and measured directly for surface area to develop the estimation equation.
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Krzyżanowska, Katarzyna, i Paweł Krzyżanowski. "The use of numerical methods in the design of a formula that returns the surface of the leaves of Phragmites australis (Cav.) Trin. Ex Steud." Limnological Review 20, nr 1 (1.03.2020): 33–39. http://dx.doi.org/10.2478/limre-2020-0004.
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AbstractThe paper presents the results of calculations and a verification of numerical models developed for estimating the surface of leaves of the common reed (Phragmites australis (Cav.) Trin. Ex Steud.). The research sample consisted of 137 leaves collected from the rush zone of Lake Raduńskie Górne in 2018. The total area of leaves obtained for testing was 1932.3 cm2. To derive a formula that returns the surface of common reed foliage regression models were used – MLR (Multiple Linear Regression) and SLR (Stepwise Linear Regression). It has been shown that the measurement of basic leaf dimensions (i.e. length – L, mid-width – WM and maximum width – WX) makes it possible to define an empirical formula which, with an average accuracy of 99.9%, allows the real surface of leaves to be estimated. The modelling results were compared with formulas currently used in practice, and the measurement errors were determined using these formulas. It has been shown that the formulas used to date are subject to RMSE to the value of 1.19-2.52. The application of the developed formula (A = 0.4486 – 0.046 L + 7.9267 WM – 5.8121 WX + 0.5853 L • WX) will significantly reduce errors in leaf surface estimation (RMSE = 0.86) and thus the amount of reed transpiration and evapotranspiration, especially in the case of handling small samples (number of leaves and measurements).
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Li, Yanxi, Rui Chen, Binbin He i Sander Veraverbeke. "Forest foliage fuel load estimation from multi-sensor spatiotemporal features". International Journal of Applied Earth Observation and Geoinformation 115 (grudzień 2022): 103101. http://dx.doi.org/10.1016/j.jag.2022.103101.
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Qin, Jiang Lin. "Non-Linear Methods Could More Accurately Measure Chlorophyll Content in Grape Foliar Non-Destructively with Visible/Red-Infrared Hyperspectral". Advanced Materials Research 239-242 (maj 2011): 2376–88. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.2376.
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Efficient methods of non-destructively measuring chlorophyll content (Chl) across a wide range of greenness in grape leaves are necessary for a producer to effectively monitor the status of the crop. Wet chemical methods and handheld leaf Chl meters such as the Minolta SPAD-502 Chl meter(Markwell,1995) have traditionally been used for this purpose. Recently, the availability of small and affordable radiometers , which uses Near infra-red and Red edge(CIred edge)( Mark R. Steel, 2008b), for Chl estimation in grapevine leaves, has provided means to estimate Chl from reflectance measurements. The two methods were equally accurate measuring pigments at low to moderate Chl levels. But, when Chl exceeded 300 mg/m2, SPAD sensitivity to Chl declined noticeably and the accuracy of Chl estimation by the CIred edge was much higher than that of the SPAD meter, the chlorophyll index was found to be capable of accurately estimating pigment contents across a much greater Chl range than the SPAD meter. However, in this paper an artificial-intelligence technique, the Support Vector Machine (SVMLightV6.01) model was introduced to establish the relationship between the Chlorophylls content and reflectance of 400-750 nm spectrum, variation of species and growth stages, which can much more perfectly compensated the reflectance that was absorpted by anthocyanin and carotenoids and scatterd because of different leaf thickness, density, or surface properties. As a result that we have solved the problems such as saturation and/or asymptote in high/or lower content of chlorophyll, and SVM model was found to be capable of more accurately estimating pigment contents across a greater range than the SPAD and CIred edge, thus it can be used for quantitative assessment of early stages of pant stress.
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Tsutsumida, Narumasa, Nagai Shin i Tomoaki Miura. "Evaluation of Land Surface Phenology for Autumn Leaf Color Change Based on Citizen Reports across Japan". Remote Sensing 14, nr 9 (22.04.2022): 2017. http://dx.doi.org/10.3390/rs14092017.
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Autumn foliage color is an important phenological characteristic associated with climate and appeals to populations as a cultural ecosystem service (CES). Land surface phenology (LSP) analyzed using time-series remotely sensed imagery can facilitate the monitoring of autumn leaf color change (ALCC); however, the monitoring of autumn foliage by LSP approaches is still challenging because of complex spatio-temporal ALCC patterns and observational uncertainty associated with remote sensing sensors. Here, we evaluated the performance of several LSP analysis approaches in estimation of LSP-based ALCCs against the ground-level autumn foliage information obtained from 758 sightseeing (high CES) sites across Japan. The ground information uniquely collected by citizens represented ALCC stages of greening, early, peak, late, and defoliation collected on a daily basis. The ALCC was estimated using a second derivative approach, in which normalized difference vegetation index (NDVI), kernel normalized difference vegetation index (kNDVI), enhanced vegetation index (EVI), two-band enhanced vegetation index (EVI2), and green red vegetation index (GRVI) were applied based on MODerate resolution Imaging Spectroradiometer (MODIS) MOD09A1 with four (Beck, Elmore, Gu, and Zhang) double logistic smoothing methods in 2020. The results revealed inconsistency in the estimates obtained using different analytical methods; those obtained using EVI with the Beck model estimated the peak stage of the ALCC relatively well, while the estimates obtained using other indices and models had high discrepancies along with uncertainty. Our study provided insights on how the LSP approach can be improved toward mapping the CESs offered by autumn foliage.
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Nunes, Matheus H., Matthew P. Davey i David A. Coomes. "On the challenges of using field spectroscopy to measure the impact of soil type on leaf traits". Biogeosciences 14, nr 13 (14.07.2017): 3371–85. http://dx.doi.org/10.5194/bg-14-3371-2017.
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Abstract. Understanding the causes of variation in functional plant traits is a central issue in ecology, particularly in the context of global change. Spectroscopy is increasingly used for rapid and non-destructive estimation of foliar traits, but few studies have evaluated its accuracy when assessing phenotypic variation in multiple traits. Working with 24 chemical and physical leaf traits of six European tree species growing on strongly contrasting soil types (i.e. deep alluvium versus nearby shallow chalk), we asked (i) whether variability in leaf traits is greater between tree species or soil type, and (ii) whether field spectroscopy is effective at predicting intraspecific variation in leaf traits as well as interspecific differences. Analysis of variance showed that interspecific differences in traits were generally much stronger than intraspecific differences related to soil type, accounting for 25 % versus 5 % of total trait variation, respectively. Structural traits, phenolic defences and pigments were barely affected by soil type. In contrast, foliar concentrations of rock-derived nutrients did vary: P and K concentrations were lower on chalk than alluvial soils, while Ca, Mg, B, Mn and Zn concentrations were all higher, consistent with the findings of previous ecological studies. Foliar traits were predicted from 400 to 2500 nm reflectance spectra collected by field spectroscopy using partial least square regression, a method that is commonly employed in chemometrics. Pigments were best modelled using reflectance data from the visible region (400–700 nm), while all other traits were best modelled using reflectance data from the shortwave infrared region (1100–2500 nm). Spectroscopy delivered accurate predictions of species-level variation in traits. However, it was ineffective at detecting intraspecific variation in rock-derived nutrients (with the notable exception of P). The explanation for this failure is that rock-derived elements do not have absorption features in the 400–2500 nm region, and their estimation is indirect, relying on elemental concentrations covarying with structural traits that do have absorption features in that spectral region (constellation effects). Since the structural traits did not vary with soil type, it was impossible for our regression models to predict intraspecific variation in rock-derived nutrients via constellation effects. This study demonstrates the value of spectroscopy for rapid, non-destructive estimation of foliar traits across species, but highlights problems with predicting intraspecific variation indirectly. We discuss the implications of these findings for mapping functional traits by airborne imaging spectroscopy.
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Devaux, A., J. Brodeur, C. Hamel i G. Tremblay. "Effet des taches foliaires causées par le Phaeosphaeria nodorum inoculé à différents stades de développement sur le rendement du blé de printemps". Phytoprotection 79, nr 2 (12.04.2005): 55–62. http://dx.doi.org/10.7202/706134ar.
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Des études en serre ont été réalisées pour évaluer l'effet du Phaeosphaeria nodorum sur le rendement du blé de printemps (Triticum aestivum, cv. Laval 19). Les plants de blé étaient inoculés aux stades gonflement épiaison, pleine floraison et grain laiteux. L'essai a été réalisé au cours de l'hiver 1993 et répété au cours de l'hiver 1994. L'inoculation du champignon pathogène P. nodorum entraîne généralement une augmentation significative de la surface foliaire infectée et une réduction du rendement comparativement aux témoins non inoculés. La surface foliaire infectée mesurée uniquement sur la feuille étendard est similaire à celle mesurée sur la plante entière. Le stade phénologique a un effet significatif sur toutes les variables observées: surface foliaire infectée, poids des tiges et des feuilles, poids des épis, poids des grains, poids des biomasses végétative et totale et indice de récolte. L'inoculation du pathogène au stade grain laiteux, le plus tardif de l'étude, semble avoir provoqué moins d'effets négatifs sur le rendement du blé comparativement aux trois autres stades étudiés. Selon les résultats de cette étude et les observations réalisées au Québec au cours des 15 dernières années, il est peu probable que les taches foliaires causées par le P. nodorum provoquent des baisses appréciables de rendement du blé de printemps au Québec.
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Moroh Joseph, Akaza, Goré Bi Boh Nestor, Anzara Gnigouan Kadio Guy Roland i Kadio Guy Roland. "Evaluation De La Diversité Phénologique Et Morphologique De Neuf Variétés De Piment (Capsicum Spp.) Cultivées Dans La Région Du Haut-Sassandra (Côte d’Ivoire)". European Scientific Journal, ESJ 18, nr 3 (31.01.2022): 278. http://dx.doi.org/10.19044/esj.2022.v18n3p278.
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a connaissance des caractéristiques des ressources génétiques est nécessaire pour une utilisation efficiente. Or les piments cultivés dans la région du Haut-Sassandra, en Côte d’Ivoire sont insuffisamment caractérisés. Pour déterminer leur diversité phénologique et morphologique, neuf variétés cultivées dans cette région ont été caractérisées à partir de huit paramètres quantitatifs dans un essai en blocs aléatoires complets de neuf traitements avec trois répétitions. Les analyses ont mis en évidence des groupes de variétés aux caractéristiques opposées. Ainsi, une variété, avec le délai de germination le plus court (5 jours), la hauteur de plante la plus élevée (23 cm), la meilleure croissance latérale, la densité du feuillage la plus grande et la surface foliaire la plus faible (11,62 cm2), s’est nettement distinguée des autres. Aussi, avec un long délai de germination (8 à 9 jours), des plantes de plus faibles diamètres et hauteurs (15 à 16 cm), des surfaces foliaires, des nombres de ramifications, des longueurs de ramification la plus développée, des envergures de frondaison et densités de feuillage moyens, quatre variétés se sont distinguées des quatre autres variétés présentant des valeurs de paramètres intermédiaires. Les neuf variétés de piment étudiées présentent une importante diversité liée à la germination, la hauteur de plante et la surface foliaire. Les caractéristiques de certaines variétés ont été semblables. Il ressort de ces résultats que la diversité en sein des piments est efficacement mise en évidence avec le délai de germination, la hauteur de la plante, la surface foliaire et peut être exploitée en sélection.
la plus grande et la surface foliaire la plus faible (11,62 cm2), s’est nettement distinguée des autres. Aussi, avec un long délai de germination (8 à 9 jours), des plantes de plus faibles diamètres et hauteurs (15 à 16 cm), des surfaces foliaires, des nombres de ramifications, des longueurs de ramification la plus développée, des envergures de frondaison et densités de feuillage moyens, quatre variétés se sont distinguées des quatre autres variétés présentant des valeurs de paramètres intermédiaires. Les neuf variétés de piment étudiées présentent une importante diversité liée à la germination, la hauteur de plante et la surface foliaire. Les caractéristiques de certaines variétés ont été semblables. Il ressort de ces résultats que la diversité en sein des piments est efficacement mise en évidence avec le délai de germination, la hauteur de la plante, la surface foliaire et peut être exploitée en sélection.
Also, four varieties, with a long germination time (8 to 9 days), plants of smaller diameters and heights (15 to 16 cm), average leaf areas, numbers of branches, length of the most developed branch, canopy size and foliage density differed from the other four varieties with intermediate parameter values. The nine varieties of chilli studied show significant diversity linked to germination, plant height and leaf surface.The characteristics of some varieties are similar. As a consequence of these results, the diversity within peppers is effectively revealed with time to germination, plant height, area of leaf and is to be exploited in breeding.
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Régnière, Jacques, Timothy J. Lysyk i Michel Auger. "POPULATION DENSITY ESTIMATION OF SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE) ON BALSAM FIR AND WHITE SPRUCE FROM 45-CM MID-CROWN BRANCH TIPS". Canadian Entomologist 121, nr 3 (marzec 1989): 267–81. http://dx.doi.org/10.4039/ent121267-3.
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AbstractThe 45-cm mid-crown branch tip from balsam fir and white spruce is described in terms of surface area, fresh weight, and bud density. Fresh weight is suggested as the most appropriate unit to express density of all stages of the spruce budworm’s, Choristoneura fumiferana (Clem.), life cycle, particularly for the purposes of comparisons between host species and locations with different foliage conditions.Changes in distribution of the spruce budworm in the crown of balsam fir are documented for all stages of the insect’s life cycle. Correction factors to account for these changes when estimating density on the basis of the 45-cm branch tip sampling unit are given for balsam fir and white spruce.The amount of error in detection of spruce budworm larvae on foliage of both host trees by sampling personnel varied systematically and consistently as a function of insect development. A method to compensate for this type of error is also suggested.
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Makowski, D., R. Bancal i A. Vicent. "Estimation of Leaf Wetness Duration Requirements of Foliar Fungal Pathogens with Uncertain Data—An Application to Mycosphaerella nawae". Phytopathology® 101, nr 11 (listopad 2011): 1346–54. http://dx.doi.org/10.1094/phyto-01-11-0024.
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Wetness of the host surface is a critical environmental factor for the development of foliar fungal diseases, but it is difficult to estimate the wetness durations required by pathogens for infection when only few experimental data are available. In this paper, we propose a method to estimate wetness duration requirements of foliar fungal pathogens when precise experimental data are not available. The proposed method is based on approximate Bayesian computation. It only requires lower and upper bounds of wetness duration requirements for one or fewer temperatures. We describe the method, show how to apply it to an infection model, and then present a case study on Mycosphaerella nawae, the causal agent of circular leaf spot of persimmon. In this example, the parameters of a simple infection model were estimated using experimental data found in the literature for the pathogen, and the model was applied to assess the risk in a Spanish area recently affected by the disease. The results showed that the probability of successful infection was higher than 0.5 for 32% of the on-site wetness durations recorded in the affected area. Results obtained with simulated data showed that our method was able to improve the estimation of wetness duration requirement. Given the flexibility of the proposed method, we expect it to become adopted for assessing the risk of introduction of exotic fungal plant pathogens.
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Rajab Pourrahmati, Manizheh, Nicolas Baghdadi i Ibrahim Fayad. "Comparison of GEDI LiDAR Data Capability for Forest Canopy Height Estimation over Broadleaf and Needleleaf Forests". Remote Sensing 15, nr 6 (10.03.2023): 1522. http://dx.doi.org/10.3390/rs15061522.
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The GEDI LiDAR system was specifically designed to detect vegetation structure and has proven to be a suitable tool for estimating forest biophysical parameters, especially canopy height, at a global scale. This study compares the GEDI relative height metric (RH100) over different forest types, especially deciduous broadleaf and evergreen coniferous located in Thuringia, Germany, to understand how the forest structural differences affect the GEDI height estimation. A canopy height model that was produced using digital terrain and surface models (DTM and DSM) derived from airborne laser scanning data is used as the reference data. Based on the result, GEDI canopy height over needleleaf forest is slightly more accurate (RMSE = 6.61 m) than that over broadleaf (RMSE = 8.30 m) and mixed (RMSE = 7.94 m) forest. Evaluation of the GEDI acquisition parameters shows that differences in beam type, sensitivity, and acquisition time do not significantly affect the accuracy of canopy heights, especially over needleleaf forests. Considering foliage condition impacts on canopy height estimation, the contrasting result is observed in the broadleaf and needleleaf forests. The GEDI dataset acquired during the winter when deciduous species shed their leaves (the so-called leaf-off dataset), outperforms the leaf-on dataset in the broadleaf forest but shows less accurate results for the needleleaf forest. Considering the effect of the plant area index (PAI) on the accuracy of the GEDI canopy height, the GEDI dataset is divided into two sets with low and high PAI values with a threshold of median PAI = 2. The results show that the low PAI dataset (median PAI < 2) corresponds to the non-growing season (autumn and winter) in the broadleaf forest. The results using the leaf-off/leaf-on season dataset are in line with the slightly better performance of GEDI using the non-growing dataset (RMSE = 7.40 m) compared to the growing dataset (RMSE = 8.44 m) in the deciduous broadleaf forest and vice versa as well as the slightly better result using the growing dataset (RMSE = 6.38 m) compared to the non-growing dataset (RMSE = 7.24 m) in the evergreen needleleaf forest. Although a slight improvement in canopy height estimation was observed using either the leaf-off or non-growing season dataset for broadleaf forest, and either the leaf-on or growing season dataset for needleleaf forest, the approach of filtering GEDI data based on such seasonal acquisition time is recommended when retrieving canopy height over pure stands of broadleaf or needleleaf species, and the sufficient dataset is available.
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Shabanov, Nikolay V., Vyacheslav A. Egorov, Tatiana S. Miklashevich, Ekaterina A. Stytsenko i Sergey A. Bartalev. "Utility of Leaf Area Index for Monitoring Phenology of Russian Forests". Remote Sensing 15, nr 22 (19.11.2023): 5419. http://dx.doi.org/10.3390/rs15225419.
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Retrievals of land surface phenology metrics depend on the choice of base variables selected to quantify the seasonal “greenness” profile of vegetation. Commonly used variables are vegetation indices, which curry signal not only from vegetation but also from the background of sparse foliage, they saturate over the dense foliage and are also affected by sensor bandwidth, calibration, and illumination/view geometry, thus introducing bias in the estimation of phenometrics. In this study we have intercompared the utility of LAI and other biophysical variables (FPAR) and radiometric parameters (NDVI and EVI2) for phenometrics retrievals. This study was implemented based on MODIS products at a resolution of 230 m over the entire extent of Russian forests. Free from artifacts of radiometric parameters, LAI exhibits a better utilization of its dynamic range during the course of seasonal variations and better sensitivity to the actual foliage “greenness” changes and its dependence on forest species. LAI-based retrievals feature a more conservative estimate of the duration of the growing season, including late spring (9.3 days) and earlier fall (8.9 days), compared to those retrieved using EVI2. In this study, we have tabulated typical values of the key phenometrics of 12 species in Russian forests. We have also demonstrated the presence of the latitudinal dependence of phenometrics over the extent of Russian forests.
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Gomes, Heliofábio Barros, Rosiberto S. da S. Junior, Frederico Tejo De Paci, Danilo K. C. De Lima, Pedro H. P. De Castro, Fabiano Barbosa dos Santos, Samuellson L. Cabral i Rosana A. Ferreira. "Mapeamento Temático da Cobertura Vegetal na Microrregião do Sertão do São Francisco Alagoano, Utilizando Imagens TM LANDSAT 5 (Thematic Mapping of Plant Cover in Microregion Sertão of the San Francisco Alagoas, Images Using TM LANDSAT 5)". Revista Brasileira de Geografia Física 5, nr 5 (3.01.2013): 1121. http://dx.doi.org/10.26848/rbgf.v5i5.232823.
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Atualmente o uso de técnicas de gerenciamento de fazendas utilizando ferramentas de agricultura de precisão vem se tornando cada vez mais comum. Uma dessas ferramentas é a obtenção de informações da resposta espectral dos alvos, cujas aplicações exigem a consideração de vários fatores como a textura do solo e o tipo de vegetação em estudo, pois os mesmos podem influenciar na interpretação dos dados. Os índices de vegetação têm sido muito utilizados no monitoramento de áreas vegetadas, na determinação e estimativa do índice de área foliar, biomassa e da radiação fotossinteticamente ativa. Os índices foram calculados através de etapas do Algoritmo SEBAL (Balanço de Energia da Superfície do Solo), mediante dados de imagens do TM – LANDSAT 5. Os resultados mostraram que ocorreu uma variação na cobertura vegetal da região em estudo, no sentido de alteração negativa da densidade e biomassa. A variação da densidade foi mais acentuada em 2008 do que em 2006 conforme resultados apresentados nos índices estudados. Os resultados obtidos demonstraram que o algoritmo SEBAL teve bom desempenho em escala regional na estimativa dos Índices de Vegetação, com potenciais para serem aplicados em áreas onde a disponibilidade de dados meteorológicos são limitantes.Palavras-chave: NDVI, SAVI, Sensoriamento Remoto. Thematic Mapping of Plant Cover in Microregion Sertão of the San Francisco Alagoas, Images Using TM LANDSAT 5 ABSTRACTCurrently the use of farm management techniques using tools of precision agriculture is becoming increasingly common. One such tool is to obtain information from the spectral response of the targets whose applications require consideration of several factors such as soil texture and type of vegetation in the study, as they may influence the interpretation of data. The vegetation indices have been used in the monitoring of vegetated areas, the determination and estimation of leaf area index, biomass and PAR. Rates were calculated using the algorithm steps of the SEBAL (Surface Energy Balance of Soil) upon image data from TM – LANDSAT 5. The results showed that there was a change in the vegetation of the study area in order to change negative density and biomass. The variation of density was larger in 2008 than in 2006 according to results presented in the indices studied. The results showed that the algorithm SEBAL performed well on a regional scale in the estimation of vegetation indices, with potential for application in areas where the availability of meteorological data are limited.Keywords: NDVI, SAVI, REMOTE SENSING.
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Williamson, Nathan M., i James K. Agee. "Heat content variation of interior Pacific Northwest conifer foliage". International Journal of Wildland Fire 11, nr 1 (2002): 91. http://dx.doi.org/10.1071/wf01046.
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Heat content with and without ash was measured for foliage of three interior Pacific Northwest conifers (Pinus ponderosa, Pseudotsuga menziesii, and Abies grandis/concolor) in five locations in Oregon and Washington. Heat content with ash did not vary by species (20.47–20.59 MJ kg–1), but ash content did vary, so that heat content without ash varied by species. Heat content also varied by location but, due to confounding with season, these differences should be viewed with caution. Foliar heat content values averaged about 10% higher than those used for surface fuels in standard fire behavior fuel models. If heat content is included in future models of crown fire behavior, errors in using heat contents that are too low may have a larger impact than most errors in estimating foliar moisture content, but sources of error might be overwhelmed by other errors in estimating crown fire energy balance.
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Giuliani, Rita, Eugenio Magnanini i Luca Corelli Grappadelli. "A Custom-built Scanner for the Estimation of the Radiation Intercepted by a Tree Canopy". HortScience 32, nr 3 (czerwiec 1997): 531D—531. http://dx.doi.org/10.21273/hortsci.32.3.531d.
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This work proposes a methodology, by light-scanning below the canopy, to directly estimate the photon flux radiation (400–1200 nm) intercepted by single or row canopies. The system is based on the assumption that the light intercepted by the canopy, at a particular time, corresponds to the difference between the incoming potential radiation on a ground surface area (able to include the ground area shaded by the canopy), and the actual radiation influx to that area in presence of the canopy. To this purpose, light-scanning equipment has been designed, built, and tested, whose main components are two aligned multi-sensor bars (1.2 m long) and a CR10 data logger, equipped with an AM 416 Relay Multiplexer (Campbell Sci. Ltd., U.K.). The radiation sensors (BPW 14N TELEFUNKEN) were chosen because of their spectral sensitivity, along with low cost. The sensors have been placed along the bars, at 5-cm intervals, and fitted with a Teflon® diffuser to provide a cosine correction. Radiation measurements are taken moving parallelly the bars on the ground, step by step, to monitor a sample point grid (5 cm by step length). Preliminary radiation scans were taken during the summer in a 3-year-old peach orchard, trained as delayed vasette. Measurements were taken for a single canopy at various hours of the day. Moreover, radiation scans were taken at the same hour, over a 3-day timespan, while gradually defoliating the canopy. A custom-built software program has been developed for data handling. Mathcad software (Mathsoft Inc., U.S.) has been used to display the canopy shade image projected on the ground, the quantum map of the monitored area, and to calculate the light influx on the whole canopy. Moreover, the light spots on the ground determined by foliage gaps have been identified and the amount of radiation reaching the ground has been be estimated.
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Murthy, Ramesh, i Phillip M. Dougherty. "Estimating Foliage Area of Loblolly Pine Shoots". Forest Science 43, nr 2 (1.05.1997): 299–303. http://dx.doi.org/10.1093/forestscience/43.2.299.
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Abstract In this study, foliage surface area of loblolly pine (Pinus taeda L.) shoots from plants grown in a 2 x 2 factorial study of nutrients and water and three levels of CO2 was predicted by flush (growth cycle). Harms (1971) predicted foliage surface area of a flush from the weighted product of foliated flush length and average needle length. In the present study flush foliage surface area was predicted using the product of the natural log of foliated flush length and average fascicle length, and an additional independent variable fascicle density. Equations generated for each of the whole-plot treatment combinations did not differ significantly, therefore one prediction equation was developed for all whole-plot treatment combinations. Flush location significantly affected prediction of flush foliage area, therefore separate equations for predicting flush surface area were developed for the main and lateral shoots. The equations explained 96% of the variation in predicting flush foliage surface area for both main and lateral shoots with fascicle density explaining an extra 12% of the variation. The equations predicted flush foliage surface area with an average absolute percent deviation of predicted values of 16.1% and 12.6% for the main and lateral shoots. For. Sci. 43 (2):299-303.
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Bourgeois, G., C. Brodeur i A. C. Kushalappa. "Effet de la brûlure cercosporéenne, causée par le Cercospora carotae, sur le développement, la croissance et le rendement de la carotte". Phytoprotection 79, nr 1 (12.04.2005): 9–19. http://dx.doi.org/10.7202/706131ar.
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L'objectif de cette étude était de quantifier l'effet de la sévérité de la brûlure cercosporéenne (Cercospora carotae) sur le développement (stades végétatifs), la croissance (poids secs du feuillage et des racines, indice de surface foliaire) et le rendement de la carotte (Daucus carota var. sativa). Au cours d'expériences effectuées en sol organique durant les saisons 1990, 1991 et 1992, trois niveaux de sévérité ont été obtenus par des nombres différents d'applications de fongicides, à savoir aucune application, deux ou trois applications et une application à chaque semaine. Au cours des trois années, des différences entre les traitements ont été observées 60 jours après le semis pour la sévérité de la maladie, 80 jours après le semis pour le poids sec du feuillage et l'indice de surface foliaire, et 100 jours après le semis pour le poids sec des racines. Une augmentation du nombre d'applications a permis une augmentation du rendement total en carottes. Cependant, les applications hebdomadaires n'ont pas augmenté le rendement en carottes de classe régulière par rapport à deux ou trois applications pour l'ensemble de la saison. Il est donc possible de réduire le nombre d'applications de fongicides, tout en conservant un rendement économiquement acceptable.
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Majasalmi, Titta, i Ryan M. Bright. "Evaluation of leaf-level optical properties employed in land surface models". Geoscientific Model Development 12, nr 9 (5.09.2019): 3923–38. http://dx.doi.org/10.5194/gmd-12-3923-2019.
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Abstract. Vegetation optical properties have a direct impact on canopy absorption and scattering and are thus needed for modeling surface fluxes. Although plant functional type (PFT) classification varies between different land surface models (LSMs), their optical properties must be specified. The aim of this study is to revisit the “time-invariant optical properties table” of the Simple Biosphere (SiB) model (later referred to as the “SiB table”) presented 30 years ago by Dorman and Sellers (1989), which has since been adopted by many LSMs. This revisit was needed as many of the data underlying the SiB table were not formally reviewed or published or were based on older papers or on personal communications (i.e., the validity of the optical property source data cannot be inspected due to missing data sources, outdated citation practices, and varied estimation methods). As many of today's LSMs (e.g., the Community Land Model (CLM), the Jena Scheme of Atmosphere Biosphere Coupling in Hamburg (JSBACH), and the Joint UK Land Environment Simulator (JULES)) either rely on the optical properties of the SiB table or lack references altogether for those they do employ, there is a clear need to assess (and confirm or correct) the appropriateness of those being used in today's LSMs. Here, we use various spectral databases to synthesize and harmonize the key optical property information of PFT classification shared by many leading LSMs. For forests, such classifications typically differentiate PFTs by broad geo-climatic zones (i.e., tropical, boreal, temperate) and phenology (i.e., deciduous vs. evergreen). For short-statured vegetation, such classifications typically differentiate between crops, grasses, and photosynthetic pathway. Using the PFT classification of the CLM (version 5) as an example, we found the optical properties of the visible band (VIS; 400–700 nm) to fall within the range of measured values. However, in the near-infrared and shortwave infrared bands (NIR and SWIR; e.g., 701–2500 nm, referred to as “NIR”) notable differences between CLM default and measured values were observed, thus suggesting that NIR optical properties are in need of an update. For example, for conifer PFTs, the measured mean needle single scattering albedo (SSA, i.e., the sum of reflectance and transmittance) estimates in NIR were 62 % and 78 % larger than the CLM default parameters, and for PFTs with flat leaves, the measured mean leaf SSA values in NIR were 20 %, 14 %, and 19 % larger than the CLM defaults. We also found that while the CLM5 PFT-dependent leaf angle values were sufficient for forested PFTs and grasses, for crop PFTs the default parameterization appeared too vertically oriented, thus warranting an update. In addition, we propose using separate bark reflectance values for conifer and deciduous PFTs and demonstrate how shoot-level clumping correction can be incorporated into LSMs to mitigate violations of turbid media assumption and Beer's law caused by the nonrandomness of finite-sized foliage elements.
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Fiala, Vincent, Jean-Pierre Boutin, Patrick Barry i Sylvie Derridj. "Les métabolites de surface foliaire (phylloplan): présence et rôle dans les relations plante-insecte". Acta Botanica Gallica 140, nr 2 (styczeń 1993): 207–16. http://dx.doi.org/10.1080/12538078.1993.10515583.
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Altimir, N., P. Kolari, J. P. Tuovinen, T. Vesala, J. Bäck, T. Suni, M. Kulmala i P. Hari. "Foliage surface ozone deposition: a role for surface moisture?" Biogeosciences 3, nr 2 (15.05.2006): 209–28. http://dx.doi.org/10.5194/bg-3-209-2006.
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Abstract. This paper addresses the potential role of surface wetness in ozone deposition to plant foliage. We studied Scots pine foliage in field conditions at the SMEARII field measurement station in Finland. We used a combination of data from flux measurement at the shoot (enclosure) and canopy scale (eddy covariance), information from foliage surface wetness sensors, and a broad array of ancillary measurements such as radiation, precipitation, temperature, and relative humidity. Environmental conditions were defined as moist during rain or high relative humidity and during the subsequent twelve hours from such events, circumstances that were frequent at this boreal site. From the measured fluxes we estimated the ozone conductance using it as the expression of the strength of ozone removal surface sink or total deposition. Further, we estimated the stomatal contribution and the remaining deposition was interpreted and analysed as the non-stomatal sink. The combined time series of measurements showed that both shoot and canopy-scale ozone total deposition were enhanced when moist conditions occurred. On average, the estimated stomatal deposition accounted for half of the measured removal at the shoot scale and one third at the canopy scale. However, during dry conditions the estimated stomatal uptake predicted the behaviour of the measured deposition, but during moist conditions there was disagreement. The estimated non-stomatal sink was analysed against several environmental factors and the clearest connection was found with ambient relative humidity. The relationship disappeared under 70% relative humidity, a threshold that coincides with the value at which surface moisture gathers at the foliage surface according to the leaf surface wetness measurements. This suggests the non-stomatal ozone sink on the foliage to be modulated by the surface films. We attempted to extract such potential modulation with the estimated film formation via the theoretical expression of adsorption. Whereas this procedure could predict the behaviour of the non-stomatal sink, it implied a chemical sink that was not accountable as simple ozone decomposition. We discuss the existence of other mechanisms whose relevance in the removal of ozone needs to be clarified, in particular: a significant nocturnal stomatal aperture neglected in the estimations, and a potentially large chemical sink offered by reactive biogenic organic volatile compounds.
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Altimir, N., P. Kolari, J. P. Tuovinen, T. Vesala, J. Bäck, T. Suni, M. Kulmala i P. Hari. "Foliage surface ozone deposition: a role for surface moisture?" Biogeosciences Discussions 2, nr 6 (22.11.2005): 1739–93. http://dx.doi.org/10.5194/bgd-2-1739-2005.
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Abstract. This paper addresses the potential role of surface wetness in ozone deposition to plant foliage. We studied Scots pine foliage in field conditions at the SMEARII field measurement station in Finland. We used a combination of data from flux measurement at the shoot (enclosure) and canopy scale (eddy covariance), information from foliage surface wetness sensors, and a broad array of ancillary measurements such as radiation, precipitation, temperature, and relative humidity. Environmental conditions were defined as moist during rain or high relative humidity, and the subsequent 12 h from such events, circumstances that were frequent at this boreal site. From the measured fluxes we estimated the ozone conductance as the expression of the strength of the ozone removal surface sink or total deposition. Further, the stomatal contribution was estimated and the remaining deposition was analysed as non-stomatal sink. The combined time series of measurements showed that both shoot and canopy-scale ozone total deposition were enhanced when moist conditions occurred. On average, the estimated stomatal deposition accounted for half of the measured removal at the shoot scale and one third at the canopy scale. However, during dry conditions the estimated stomatal uptake predicted the behaviour of the measured deposition, but during moist conditions there was disagreement. The estimated non-stomatal sink was analysed against several environmental factors and the clearest correspondence was found with ambient relative humidity. The relationship disappeared under 70% relative humidity, a threshold that coincides with the value at which surface moisture gathers at the foliage surface according to the leaf surface wetness measurements. This suggests the non-stomatal ozone sink on the foliage to be modulated by the surface films. We attempted to extract such potential modulation with the estimated film formation via the theoretical expression or adsorption isotherm. Whereas this procedure could predict the behaviour of the non-stomatal sink, it implied a chemical sink that was not accountable as simple ozone decomposition. We discuss the existence of other mechanisms whose relevance needs to be clarified, in particular: a significant stomatal aperture neglected in the estimations, and a potentially large chemical sink offered by reactive biogenic organic volatile compounds.
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Schneider, Christophe. "Influence de la suppression des entre-coeurs de souches de vigne sur le microclimat lumineux et la récolte". OENO One 19, nr 1 (31.03.1985): 17. http://dx.doi.org/10.20870/oeno-one.1985.19.1.1313.
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<p style="text-align: justify;">Cet essai concerne les effets de la suppression continue, après la nouaison, des entre-coeurs de souches de vigne sur le microclimat lumineux et la récolte.</p><p style="text-align: justify;">II apparaît que l'amputation de la part importante de surface foliaire représentée par les entre-coeurs (1/4 à 1/2) est compensée par une meilleure exposition du feuillage conservé.</p><p style="text-align: justify;">La production et la richesse en sucres des raisins ne sont pas influencées par le traitement alors que l'acidité totale semble plutôt diminuée.</p><p style="text-align: justify;">En définitive, le facteur déterminant du potentiel de production de la vigne, notamment du taux de sucres des raisins est moins la surface totale du feuillage que la « surface foliaire exposée ».</p><p style="text-align: justify;">+++</p><p style="text-align: justify;">The purpose of this trial was to measure the effects of a continuous lateral shoots removing, after berry set, on grapevine microlimate and crop.</p><p style="text-align: justify;">It was found that suppression of the lateral shoots which represent an important part of the leaf area (1/4 to 1/2) is balanced by a better exposure of the remaining foliage.</p><p style="text-align: justify;">Yield and sugar content of the grapes were not affected by the handling whereas the total acidity seemed to be decreased.</p><p style="text-align: justify;">Finally, it is less the total leaf area than the « exposed leaf area » which fixes the potentialities of grapevines especially the sugar content of the grapes.</p>
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MAURER, Patricia, J. PINON i Isabelle GENETET. "Méthode de mesure de la surface foliaire lésée par Marssonina brunnea (Ell. et Ev.) Magn". Annales des Sciences Forestières 43, nr 3 (1986): 403–6. http://dx.doi.org/10.1051/forest:19860309.
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Arseniou, Georgios, David W. MacFarlane i Dominik Seidel. "Measuring the Contribution of Leaves to the Structural Complexity of Urban Tree Crowns with Terrestrial Laser Scanning". Remote Sensing 13, nr 14 (14.07.2021): 2773. http://dx.doi.org/10.3390/rs13142773.
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Trees have a fractal-like branching architecture that determines their structural complexity. We used terrestrial laser scanning technology to study the role of foliage in the structural complexity of urban trees. Forty-five trees of three deciduous species, Gleditsia triacanthos, Quercus macrocarpa, Metasequoia glyptostroboides, were sampled on the Michigan State University campus. We studied their structural complexity by calculating the box-dimension (Db) metric from point clouds generated for the trees using terrestrial laser scanning, during the leaf-on and -off conditions. Furthermore, we artificially defoliated the leaf-on point clouds by applying an algorithm that separates the foliage from the woody material of the trees, and then recalculated the Db metric. The Db of the leaf-on tree point clouds was significantly greater than the Db of the leaf-off point clouds across all species. Additionally, the leaf removal algorithm introduced bias to the estimation of the leaf-removed Db of the G. triacanthos and M. glyptostroboides trees. The index capturing the contribution of leaves to the structural complexity of the study trees (the ratio of the Db of the leaf-on point clouds divided by the Db of the leaf-off point clouds minus one), was negatively correlated with branch surface area and different metrics of the length of paths through the branch network of the trees, indicating that the contribution of leaves decreases as branch network complexity increases. Underestimation of the Db of the G. triacanthos trees, after the artificial leaf removal, was related to maximum branch order. These results enhance our understanding of tree structural complexity by disentangling the contribution of leaves from that of the woody structures. The study also highlighted important methodological considerations for studying tree structure, with and without leaves, from laser-derived point clouds.
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Xu, Li, Hongyan Lai, Jinge Yu, Shaolong Luo, Chaosheng Guo, Yingqun Gao, Wenwu Zhou, Shuwei Wang i Qingtai Shu. "Carbon Storage Estimation of Quercus aquifolioides Based on GEDI Spaceborne LiDAR Data and Landsat 9 Images in Shangri-La". Sustainability 15, nr 15 (25.07.2023): 11525. http://dx.doi.org/10.3390/su151511525.
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The assessment of forest carbon storage plays a crucial role in forest management and ecosystem exploration, enabling the evaluation of forest quality, resources, carbon cycle and management. The Global Ecosystem Dynamics Investigation (GEDI) satellite provides a means to accurately measure these various forest vertical structure parameters by penetrating the forest canopy. However, the distribution of the footprint along the orbit track is heterogeneous and discontinuous, preventing the acquisition of spatially distributed carbon storage formation at the county level. Consequently, this study integrated GEDI and Landsat 9 data to estimate Quercus aquifolioides carbon storage in Shangri-La. By applying the Kriging interpolation to previously pretreated footprints, surface information from the GEDI L2B footprints was obtained. At the same time, Landsat 9 vegetation indices and band reflectance were extracted to analyze the correlation with the carbon storage of Quercus aquifolioides samples. Then, three methods (support vector machine, bagging, and random forest) were used to create a carbon storage estimation model for Shangri-La. The research results showed that (1) among the models for the selection of GEDI footprint parameters based on semi-variance, the optimal model of the digital_elevation_model was the spherical model, while the best model of percentage tree cover from the MODIS data (modis_treecover) and the foliage height diversity index (fhd_normal) was the exponential model. (2) Analyzing the thirty-three extracted independent variable factors correlated with the carbon storage of Quercus aquifolioides showed that the top five variables with the highest correlation were digital_elevation_model, modis_treecover, fhd_normal, DEM, and band 1 (B1). (3) After variable selection, the R2 = 0.82 and RMSE = 11.92 t/hm2 values of the Quercus aquifolioides carbon storage estimation model established via random forest were obtained, and its evaluation precision was superior to that of the support vector machine method and bagging regression. The carbon storage of Quercus aquifolioides was primarily in the range of 8.22~94.63 t/hm2, and the mean value was 42.44 t/hm2, while the total carbon storage was about 5,374,137.62 t. The findings from this paper illustrated the feasibility of obtaining carbon storage data on a county scale by combining GEDI LiDAR data with Landsat 9 optical data. The results also suggested a new perspective for combining GEDI L2B data with other remote sensing images to estimate other forest structure parameters.
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Henningsen, Jon Niklas, Héctor Alejandro Bahamonde, Karl Hermann Mühling i Victoria Fernández. "Tomato and Pepper Leaf Parts Contribute Differently to the Absorption of Foliar-Applied Potassium Dihydrogen Phosphate". Plants 12, nr 11 (29.05.2023): 2152. http://dx.doi.org/10.3390/plants12112152.
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Foliar fertilisation is an application technique that is increasingly being used in agriculture and offers the possibility of providing nutrients directly to the site of highest demand. Especially for phosphorus (P), foliar application is an interesting alternative to soil fertilisation, but foliar uptake mechanisms are poorly understood. To gain a better understanding of the importance of leaf surface features for foliar P uptake, we conducted a study with tomato (Solanum lycopersicum) and pepper (Capsicum annuum) plants, which have different leaf surface traits. For this purpose, drops of 200 mM KH2PO4 without surfactant were applied onto the adaxial or abaxial leaf side or to the leaf veins and the rate of foliar P absorption was evaluated after one day. Additionally, leaf surfaces were characterised in detail by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), estimating also leaf surface wettability and free energy, among other parameters. While the leaves of pepper hardly contained any trichomes, the abaxial side and the leaf veins of tomato leaves were densely covered with trichomes. The cuticle of tomato leaves was thin (approximately 50 nm), while that of pepper was thick (approximately 150–200 nm) and impregnated with lignin. Due to the fact that trichomes were most abundant in the leaf veins of tomato, dry foliar fertiliser drop residues were observed to be anchored there, and the highest P uptake occurred via tomato leaf veins, resulting in 62% increased P concentration. However, in pepper, the highest rate of P absorption was recorded after abaxial-side P treatment (+66% P). Our results provide evidence that different leaf parts contribute unequally to the absorption of foliar-applied agrochemicals, which could potentially be useful for optimising foliar spray treatments in different crops.
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Mao, J., D. M. Ricciuto, P. E. Thornton, J. M. Warren, A. W. King, X. Shi, C. M. Iversen i R. J. Norby. "Evaluating the Community Land Model in a pine stand with <sup>13</sup>CO<sub>2</sub> labeling and shading manipulations". Biogeosciences Discussions 12, nr 9 (7.05.2015): 6971–7015. http://dx.doi.org/10.5194/bgd-12-6971-2015.
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Abstract. Carbon allocation and flow through ecosystems regulate land surface–atmosphere CO2 exchange and thus is a key, albeit uncertain, component of mechanistic models. The Partitioning in Trees and Soil (PiTS) experiment-model project tracked carbon allocation through a young Pinus taeda stand following pulse-labeling with 13CO2 and two levels of shading. The field component of this project provided process-oriented data that was used to evaluate and improve terrestrial biosphere model simulations of rapid shifts in carbon allocation and hydrological dynamics under varying environmental conditions. Here we tested the performance of the Community Land Model version 4 (CLM4) in capturing short-term carbon and water dynamics in relation to manipulative shading treatments, and the timing and magnitude of carbon fluxes through various compartments of the ecosystem. For CLM4 to closely simulate pretreatment conditions, we calibrated select model parameters with pretreatment observational data. Compared to CLM4 simulations with default parameters, CLM4 with calibrated model parameters was able to better simulate pretreatment vegetation carbon pools, light response curves, and other initial states and fluxes of carbon and water. Over a 3 week treatment period, the calibrated CLM4 generally reproduced the impacts of shading on average soil moisture at 15–95 cm depth, transpiration, relative change in stem carbon, and soil CO2 efflux rate, although some discrepancies in the estimation of magnitudes and temporal evolutions existed. CLM4, however, was not able to track the progression of the 13CO2 label from the atmosphere through foliage, phloem, roots or surface soil CO2 efflux, even when optimized model parameters were used. This model bias arises, in part, from the lack of a short-term non-structural carbohydrate storage pool and progressive timing of within-plant transport, thus indicating a need for future work to improve the allocation routines in CLM4. Overall, these types of detailed evaluations of CLM4, paired with intensive field manipulations, can help to identify model strengths and weaknesses, model uncertainties, and additional observations necessary for future model development.
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Gower, Stith T., Charles C. Grier, Daniel J. Vogt i Kristiina A. Vogt. "Allometric relations of deciduous (Larixoccidentalis) and evergreen conifers (Pinuscontorta and Pseudotsugamenziesii) of the Cascade Mountains in central Washington". Canadian Journal of Forest Research 17, nr 7 (1.07.1987): 630–34. http://dx.doi.org/10.1139/x87-103.
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Logarithmic equations for estimating component biomass and projected leaf area from stem diameter and (or) sapwood cross-sectional area were computed for western larch (Larixoccidentalis Nutt.), lodgepole pine (Pinuscontorta Dougl.), and Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) in a mixed conifer stand in the Cascades of central Washington. Regression equations for estimating foliage biomass reported in this study did not compare favorably with foliage biomass allometric relations from other studies. For a given diameter, western larch supported a greater current foliage mass than lodgepole pine or Douglas-fir (P < 0.001); however, the total foliage mass of lodgepole pine was significantly greater (P < 0.001) than western larch. Despite lodgepole pine supporting a total foliage mass approximately twofold greater than western larch, allometric relations between foliage area and stem diameter were not different (P > 0.05) between the deciduous and evergreen conifer. Western larch supports a needle morphology that provides a greater photosynthetic surface area per unit of carbon invested than evergreen conifers in this environment.
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Kassambara, Ousmane, Oumar Sénou, Moussa Karembé i Ibrahim Sambaké. "Comportement Biophysique et Écophysiologique de Cinq Espèces Ligneuses en Plantation dans la Commune Rurale de Massala (Cercle de Ségou, Mali)". European Scientific Journal, ESJ 19, nr 6 (28.02.2023): 185. http://dx.doi.org/10.19044/esj.2023.v19n6p185.
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Au Mali, très peu d’études écophysiologiques ont été menées sur les espèces ligneuses notamment à leur stade juvénile. L’objectif de cette étude était d’évaluer le comportement biophysique et écophysiologique de cinq espèces ligneuses en plantation. Pour ce faire, les plants de trois espèces autochtones (Combretum micranthum, Combretum glutinosum et Piliostigma reticulatum) et deux espèces exotiques (Acacia auriculiformis et Cassia siamea) ont été produits en pépinière et plantés à l’âge de 4 mois dans un dispositif expérimental en blocs de Fisher avec 4 répétitions. Par la suite, les paramètres biophysiques (taux de survie, diamètre au collet et hauteur totale des plants) ont été évalués 29 mois après plantation alors que les paramètres écophysiologiques ou traits fonctionnels (teneur relative en eau (RWC), surface foliaire spécifique (SLA) et teneur en matière sèche foliaire (LDMC)) ont été évalués entre 12 et 24 mois après plantation pendant 4 périodes distinctes de l’année. Comme résultats obtenus, le taux de survie des plants a varié en fonction des espèces étudiées. De même, pour la croissance en hauteur et en diamètre, il a été obtenu une différence hautement significative (P<0,001) entre les cinq espèces. Concernant les traits fonctionnels, la teneur relative en eau a varié significativement en fonction d’une part de la période de l’année et d’autre part de l’espèce alors que l’interaction des deux facteurs a eu un effet significatif sur la surface foliaire spécifique et la teneur en matière sèche foliaire des plants. En outre, tous les traits fonctionnels étudiés étaient significativement corrélés entre eux. En somme, une meilleure connaissance des paramètres biophysiques et écophysiologiques peut orienter le choix d’espèces appropriées pour la plantation dans les differentes zones climatiques.
In Mali, very few ecophysiological studies have been conducted on woody species, particularly at their juvenile stage. The objective of this study was to evaluate the biophysical and ecophysiological behavior of five woody species in plantations. To do this, the plants of three native species (Combretum micranthum, Combretum glutinosum and Piliostigma reticulatum) and two exotic species (Acacia auriculiformis and Cassia siamea) were produced in the nursery and planted at the age of 4 months into an experimental device in Fisher blocks with 4 repetitions. Subsequently, the biophysical parameters (survival rate, collar diameter and total height of the plants) were evaluated 29 months after planting, while the ecophysiological parameters or functional traits (relative water content (RWC), specific leaf area (SLA) and leaf dry matter content (LDMC)) were evaluated between 12 and 24 months after planting during 4 distinct periods of the year. As results obtained, the survival rate of the plants varied according to the species studied. Likewise, for the growth in height and in diameter, a highly significant difference (P<0.001) was obtained between the five species. Regarding the functional traits, the relative water content varied significantly according to the time of year on the one hand and to the species on the other, while the interaction of the two factors had a significant effect on the specific leaf area and the leaf dry matter content of plants. Furthermore, all the functional traits studied were significantly correlated with each other. In short, a better knowledge of biophysical and ecophysiological parameters can guide the choice of appropriate species for planting in different climatic zones.
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Jaafar Omar, Sarbaz Faki, i Jassim Mohammad Aziz Al-Jubouri. "The role of adding potassium humate and foliar spraying with marine algae on the mineral content and nutritional value of Moringa". Sumer 4 8, CSS 4 (15.10.2023): 1–14. http://dx.doi.org/10.21931/rb/css/2023.08.04.05.
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An experiment was carried out in the plastic house at the Agricultural Research Station in Bani Maqam, affiliated to Jam Jamal Agriculture Directorate in Sulaymaniyah Governorate, in a randomized complete block design, with three replications, on June 10, 2021. Furthermore, 4, 8, 12 and 16 kg hectares when planting and before the first irrigation and after each mowing process, and the second factor was spraying with seaweed extract Alga000 at three levels 0, 1, and 2 ml (2 and 4 ml per liter of total spray) and at two intervals after 20 and 30 days of planting After 10 and 25 days of mowing, at a height of 20 cm from the surface of the ground, the mineral content of leaves and dry stems samples of the first mowing plants was estimated. It included the content of calcium, iron and manganese (mg/100g dry matter) and the percentage of nitrogen, phosphorous and potassium. Indicators of the nutritional value of the leaves and stems of the first mow, which included the estimation of the percentage of total carbohydrates, ash, protein and fiber. The results showed that adding 16 kg hectares of potassium humate and spraying at a concentration of 2 ml per liter twice with algae extract Bahriya recorded the highest content of iron (42.3 and 19.82), calcium (2103.7 and 1009.29) and manganese (40 and 10.15) mg/100 g of dry matter for leaves and stems. The highest percentage of phosphorous was 0.333% in dry leaves, and the highest percentage of nitrogen (3.89%) and 1.58%), potassium (1.601% and 1.24%), protein (24.314% and 9.885%), total carbohydrates (35.23% and 11.86%), and the lowest fiber content (4.57% and 25.45%) in the dry matter. For leaves and stems . Keywords: moringa, potassium humate, marine algae, mineral content, nutritional value
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Penavayre, M., René Morlat, A. Jacquet i F. Bimont. "Influence des terroirs sur la croissance et le développement de la vigne en millésime exceptionnellement sec (1990)". OENO One 25, nr 3 (30.09.1991): 119. http://dx.doi.org/10.20870/oeno-one.1991.25.3.1214.
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<p style="text-align: justify;">La croissance et le développement de la vigne ont été suivis en Val de Loire, lors d'une année à fort déficit hydrique. Les resultats ont mis en évidence un effet considérable des terroirs sur l'installation du couvert aérien. En début de cycle végétatif, la vitesse de croissance était liée à la température (air, sol), variable d'un terroir à l'autre. Par la suite, la contrainte hydrique, différente selon les sites, a orienté fortement la cinétique de mise en place de la surface foliaire et son niveau final. Le potentiel photosynthétique global a été réduit dans les terroirs présentant des réserves hydriques moindres et dans lesquels le système racinaire était limite en profondeur.</p>
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Barthou, H., R. Buis i P. Chanier. "La surface foliaire, déterminant du développement chez le Soja (Glycine max). Régulation inter-compartiments tige principale – rameaux". Canadian Journal of Botany 64, nr 12 (1.12.1986): 2878–86. http://dx.doi.org/10.1139/b86-380.
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Systematic early reduction of two-thirds of the surface of each leaf on the main stem in soya results in (i) a decrease, on the main axis, in the number of leaves formed and the total number of pods, with no change in the rate of phyllogenesis; and (ii) a stimulation of the development of axillary branches which compensate the foliar and reproductive deficit of the main stem through their growth, their leaf surface area, and the number of pods they form. For given growth conditions, it was shown that, to a certain extent, global production (vegetative and reproductive) is maintained at a constant level by compensation processes between the main stem and the branches. The existence of such relations between compartments has regulatory importance for the development of the whole plant. [Translated by the Journal]
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Rançon, Florian, Lionel Bombrun, Barna Keresztes i Christian Germain. "Comparison of SIFT Encoded and Deep Learning Features for the Classification and Detection of Esca Disease in Bordeaux Vineyards". Remote Sensing 11, nr 1 (20.12.2018): 1. http://dx.doi.org/10.3390/rs11010001.
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Grapevine wood fungal diseases such as esca are among the biggest threats in vineyards nowadays. The lack of very efficient preventive (best results using commercial products report 20% efficiency) and curative means induces huge economic losses. The study presented in this paper is centered around the in-field detection of foliar esca symptoms during summer, exhibiting a typical “striped” pattern. Indeed, in-field disease detection has shown great potential for commercial applications and has been successfully used for other agricultural needs such as yield estimation. Differentiation with foliar symptoms caused by other diseases or abiotic stresses was also considered. Two vineyards from the Bordeaux region (France, Aquitaine) were chosen as the basis for the experiment. Pictures of diseased and healthy vine plants were acquired during summer 2017 and labeled at the leaf scale, resulting in a patch database of around 6000 images (224 × 224 pixels) divided into red cultivar and white cultivar samples. Then, we tackled the classification part of the problem comparing state-of-the-art SIFT encoding and pre-trained deep learning feature extractors for the classification of database patches. In the best case, 91% overall accuracy was obtained using deep features extracted from MobileNet network trained on ImageNet database, demonstrating the efficiency of simple transfer learning approaches without the need to design an ad-hoc specific feature extractor. The third part aimed at disease detection (using bounding boxes) within full plant images. For this purpose, we integrated the deep learning base network within a “one-step” detection network (RetinaNet), allowing us to perform detection queries in real time (approximately six frames per second on GPU). Recall/Precision (RP) and Average Precision (AP) metrics then allowed us to evaluate the performance of the network on a 91-image (plants) validation database. Overall, 90% precision for a 40% recall was obtained while best esca AP was about 70%. Good correlation between annotated and detected symptomatic surface per plant was also obtained, meaning slightly symptomatic plants can be efficiently separated from severely attacked plants.
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Klosterhalfen, Anne, Alexander Graf, Nicolas Brüggemann, Clemens Drüe, Odilia Esser, María P. González-Dugo, Günther Heinemann i in. "Source partitioning of H<sub>2</sub>O and CO<sub>2</sub> fluxes based on high-frequency eddy covariance data: a comparison between study sites". Biogeosciences 16, nr 6 (19.03.2019): 1111–32. http://dx.doi.org/10.5194/bg-16-1111-2019.
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Abstract. For an assessment of the roles of soil and vegetation in the climate system, a further understanding of the flux components of H2O and CO2 (e.g., transpiration, soil respiration) and their interaction with physical conditions and physiological functioning of plants and ecosystems is necessary. To obtain magnitudes of these flux components, we applied source partitioning approaches after Scanlon and Kustas (2010; SK10) and after Thomas et al. (2008; TH08) to high-frequency eddy covariance measurements of 12 study sites covering different ecosystems (croplands, grasslands, and forests) in different climatic regions. Both partitioning methods are based on higher-order statistics of the H2O and CO2 fluctuations, but proceed differently to estimate transpiration, evaporation, net primary production, and soil respiration. We compared and evaluated the partitioning results obtained with SK10 and TH08, including slight modifications of both approaches. Further, we analyzed the interrelations among the performance of the partitioning methods, turbulence characteristics, and site characteristics (such as plant cover type, canopy height, canopy density, and measurement height). We were able to identify characteristics of a data set that are prerequisites for adequate performance of the partitioning methods. SK10 had the tendency to overestimate and TH08 to underestimate soil flux components. For both methods, the partitioning of CO2 fluxes was less robust than for H2O fluxes. Results derived with SK10 showed relatively large dependencies on estimated water use efficiency (WUE) at the leaf level, which is a required input. Measurements of outgoing longwave radiation used for the estimation of foliage temperature (used in WUE) could slightly increase the quality of the partitioning results. A modification of the TH08 approach, by applying a cluster analysis for the conditional sampling of respiration–evaporation events, performed satisfactorily, but did not result in significant advantages compared to the original method versions developed by Thomas et al. (2008). The performance of each partitioning approach was dependent on meteorological conditions, plant development, canopy height, canopy density, and measurement height. Foremost, the performance of SK10 correlated negatively with the ratio between measurement height and canopy height. The performance of TH08 was more dependent on canopy height and leaf area index. In general, all site characteristics that increase dissimilarities between scalars appeared to enhance partitioning performance for SK10 and TH08.
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Ben Abdallah, Ferjani, Nada Elloumi, Imed Mezghani, Makki Boukhris i Jean Pierre Garrec. "Réponses d’une vigne locale à une pollution fluorée". Canadian Journal of Botany 84, nr 3 (marzec 2006): 393–99. http://dx.doi.org/10.1139/b06-010.
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Les effets d’une pollution atmosphérique par des composés fluorés ont été étudiés sur des cultivars d’une vigne locale, Vitis vinifera L. ‘Asli’, cultivée aux environs d'une usine de production d'engrais phosphatés. L’étude a pour objectif de déterminer les mécanismes permettant à ces vignes autochtones de survivre dans la zone polluée. Elle a consisté à suivre le comportement de ces cultivars dans deux parcelles : l’une soumise aux fumées d’une usine polluante et l’autre au loin de toute pollution. Les paramètres mesurés sont la conductance stomatique, la teneur des feuilles en F– et en Ca2+ et l’activité photosynthétique des zones foliaires saines. Nos résultats suggèrent que la survie de la vigne est liée à une compartimentation du fluor dans les bordures et les extrémités des feuilles, avec une tendance de la plante à contourner les nouveaux tissus nécrosés par un liseré de transition conduisant au développement d’auréoles concentriques de zones nécrosées donnant au limbe un aspect de mosaïque. Ce dernier peut donner des informations intéressantes sur la qualité de l’air et l’état des plantes. Ce comportement est concomitant à une aptitude des zones foliaires saines à conserver la capacité photosynthétique de la plante, tant que les nécroses ne dépassent pas 10 % à 20 % de la surface foliaire. Outre le piégeage du fluor dans des régions foliaires particulières, la fermeture temporaire des stomates semble également contribuer à la restriction de l’accumulation de ce polluant. Par ailleurs, le parallélisme entre l’accumulation du fluor et celle du calcium suggère que ce cation est impliqué dans le piégeage et la détoxication du fluor en le séquestrant sous forme de CaF2. Enfin, nos résultats ne plaident pas en faveur d’une remobilisation foliaire du fluor qui demeure séquestré dans les feuilles les plus âgées. D’ailleurs, la contamination des baies semble se faire directement par les fumées de l'usine, et non par apports endogènes.
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Baldwin, Jr., V. C., K. D. Peterson, H. E. Burkhart, R. L. Amateis i P. M. Dougherty. "Equations for estimating loblolly pine branch and foliage weight and surface area distributions". Canadian Journal of Forest Research 27, nr 6 (1.06.1997): 918–27. http://dx.doi.org/10.1139/x97-030.
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Bahamonde, Héctor A., Carlos Pimentel, Luis Adrián Lara, Vikingur Bahamonde-Fernández i Victoria Fernández. "Foliar Application of Potassium Salts to Olive, with Focus on Accompanying Anions". Plants 12, nr 3 (19.01.2023): 472. http://dx.doi.org/10.3390/plants12030472.
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Potassium (K) is an essential element, which is often supplied to horticultural crops via foliar spraying. Some studies have investigated the effect of different foliar-applied K compounds; however, most studies have focussed on crop quality and yield parameters, or were performed with isolated leaf cuticles. The aim of this study was to evaluate the rates of the foliar ion penetration and leaf surface deposition of 130 mM K sprays of compounds with markedly different point of deliquescence (POD) and efflorescence (POE) values, the rates having been previously estimated in climate chamber trials. Shoots of field-grown, commercial olive trees were sprayed with K-nitrate (KNO3), K-sulphate (K2SO4), K-chloride (KCl), K-phosphate (K3PO4), K-carbonate (K2CO3) and K-bicarbonate (KHCO3), and leaf samples were collected after 3 and 24 h. Cation and anion concentrations were determined in the leaf tissues, and in a preliminary leaf water wash for estimating surface-deposited ion concentrations. No significant leaf tissue K increments were recorded between the K sprays. Olive tissue anion concentrations showed different patterns, and a chloride (Cl−) increase was detected 3 h after the foliar KCl supply. On the other hand, the foliar K applications led to leaf nitrate changes regardless of the K source supplied. High amounts of K and accompanying ions were recovered in the washing liquid of the foliar K-supplied leaves. Some foliar K treatments increased the leaf surface concentration of sulphate and chloride, suggesting a potential effect on leaf cell anion extrusion. Hence, despite no evidence of foliar K uptake, an effect of leaf anion concentrations was observed, indicating that foliar nutrient sprays may influence leaf and leaf surface anion balance.
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Baldwin, Jr., V. Clark, Kelly D. Peterson, Harold E. Burkhart, Ralph L. Amateis i Phillip M. Dougherty. "Erratum: Equations for estimating loblolly pine branch and foliage weight and surface area distributions". Canadian Journal of Forest Research 28, nr 7 (1.07.1998): 1097. http://dx.doi.org/10.1139/x98-096.
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Wang, X., C. J. Lin i X. Feng. "Sensitivity analysis of an updated bidirectional air–surface exchange model for elemental mercury vapor". Atmospheric Chemistry and Physics 14, nr 12 (25.06.2014): 6273–87. http://dx.doi.org/10.5194/acp-14-6273-2014.
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Abstract. A box model for estimating bidirectional air–surface exchange of gaseous elemental mercury (Hg0) has been updated based on the latest understanding of the resistance scheme of atmosphere–biosphere interface transfer. Simulations were performed for two seasonal months to evaluate diurnal and seasonal variation. The base-case results show that water and soil surfaces are net sources, while vegetation is a net sink of Hg0. The estimated net exchange in a domain covering the contiguous US and part of Canada and Mexico is 38.4 and 56.0 Mg as evasion in the summer and winter month, respectively. The smaller evasion in summer is due to the stronger Hg0 uptake by vegetation. Modeling experiments using a two-level factorial design were conducted to examine the sensitivity of flux response to the changes in physical and environmental parameters in the model. It is shown that atmospheric shear flows (surface wind over water and friction velocity over terrestrial surfaces), dissolved gaseous mercury (DGM) concentration, soil organic and Hg content, and air temperature are the most influential factors. The positive effect of friction velocity and soil Hg content on the evasion flux from soil and canopy can be effectively offset by the negative effect of soil organic content. Significant synergistic effects are identified between surface wind and DGM level for water surface, and between soil Hg content and friction velocity for soil surface, leading to ~50% enhanced flux compared to the sum of their individual effects. The air–foliage exchange is mainly controlled by surface resistance terms influenced by solar irradiation and air temperature. Research in providing geospatial distribution of Hg in water and soil will greatly improve the flux estimate. Elucidation on the kinetics and mechanism of Hg(II) reduction in soil/water and quantification of the surface resistances specific to Hg species will also help reduce the model uncertainty.
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Wang, X., C. J. Lin i X. Feng. "Sensitivity analysis of an updated bidirectional air-surface exchange model for mercury vapor". Atmospheric Chemistry and Physics Discussions 13, nr 12 (10.12.2013): 32229–67. http://dx.doi.org/10.5194/acpd-13-32229-2013.
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Abstract. A box model for estimating bidirectional air-surface exchange of gaseous elemental mercury (Hg0) has been updated based on the latest understanding of the resistance scheme of atmosphere–biosphere interface transfer. Simulations were performed for two seasonal months to evaluate diurnal and seasonal variation. The base-case results show that water and soil surfaces are net sources while vegetation is a net sink of Hg0. The estimated net exchange in a domain covering the contiguous US and part of Canada and Mexico is 38 and 56 Mg as evasion in the summer and winter month. The smaller evasion in summer is due to stronger Hg0 uptake by vegetation. Modeling experiments using a 2-level factorial design were conducted to examine the sensitivity of flux response to changes of physical and environmental parameters in the model. It is shown that atmospheric shear flow (surface wind over water and friction velocity over terrestrial surfaces), dissolved gaseous mercury (DGM) concentration, soil organic and Hg content, and air temperature are the most influential factors. The positive effect of friction velocity and soil Hg content on the evasion flux from soil and canopy can be effectively offset by the negative effect of soil organic content. Significant synergistic effects are identified between surface wind and DGM level for water surface, and between soil Hg content and friction velocity for soil surface, leading to ~50% enhanced flux compared to the sum of their individual effects. The air-foliar exchange is mainly controlled by surface resistance terms controlled by solar irradiation and air temperature. Research in providing geospatial distribution of Hg in water and soil will greatly improve the flux estimate. Elucidation on the kinetics and mechanism of Hg(II) reduction in soil/water and quantification of the surface resistances specific to Hg species will also help reduce the model uncertainty.
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FASSNACHT, K., S. GOWER, J. NORMAN i R. MCMURTRIC. "A comparison of optical and direct methods for estimating foliage surface area index in forests". Agricultural and Forest Meteorology 71, nr 1-2 (październik 1994): 183–207. http://dx.doi.org/10.1016/0168-1923(94)90107-4.
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