12 results on '"azote foliaire"'
Search Results
2. In situ estimation of foliar nitrogen in wild blueberry using reflectance spectra.
- Author
-
Maqbool, R., Percival, D. C., Adl, M. S., Zaman, Q. U., and Buszard, D.
- Subjects
BLUEBERRIES ,COMPOSITION of leaves ,PLANT physiology - Abstract
The article presents the study which conducted an in situ estimation of foliar nitrogen in wild blueberry (Vaccinium angustifolium Ait.), which is said to be a native plant in northeastern North America. The study tested the hypotheses that foliar nitrogen (N) in the plant can be estimated from canopy reflectance spectra and that the relationship between the spectra and foliar N is dependent on the specific spectral region. The study was conducted in Nova Scotia and New Brunswick.
- Published
- 2012
- Full Text
- View/download PDF
3. Canopy-scale relationships between foliar nitrogen and albedo are not observed in leaf reflectance and transmittance within temperate deciduous tree species.
- Author
-
Bartlett, Megan K., Ollinger, Scott V., Hollinger, David Y., Wicklein, Haley F., and Richardson, Andrew D.
- Subjects
- *
PLANT canopies , *PHOTOSYNTHESIS , *FOLIAR diagnosis , *CROPS , *NITROGEN , *REFLECTANCE , *TRANSMISSOMETERS , *GRISELINIA littoralis - Abstract
Strong positive correlations between the maximum rate of canopy photosynthesis, canopy-averaged foliar nitrogen concentration, and canopy albedo have been shown in previous studies. While leaf-level relationships between photosynthetic capacity and foliar nitrogen are well documented, it is not clear whether leaf-level relationships between solar-weighted reflectance and nitrogen underlie the canopy-scale patterns. Using an integrating sphere, we measured the reflectance and transmittance (350-2500 nm) of both individual leaves and multileaf stacks. Samples were collected from 12 broadleaf species at the Harvard Forest in central Massachusetts, USA. Across all species, foliar nitrogen (both mass-based nitrogen concentration and area-based nitrogen content) and leaf mass / area ratio were negatively, rather than positively, correlated with solar-weighted reflectance and transmittance in ultraviolet-visible and near-infrared wavelength bands (350-700 nm and 700-2500 nm, respectively). Leaf-level anatomy and biochemistry, therefore, do not appear to drive the canopy-level association between increasing foliar nitrogen content and increasing canopy albedo. This suggests that interactions between leaf optical properties and structural canopy-scale traits that correlate with nitrogen content (perhaps some combination of crown shape, leaf area index, leaf angular distribution, or other structural characteristics of the canopy), may instead underlie the previously observed relationship between nitrogen and canopy-level shortwave albedo. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
4. Seasonal variability of leaf area index and foliar nitrogen in contrasting dry–mesic tundras.
- Author
-
Campioli, Matteo, Michelsen, Anders, Samson, Roeland, and Lemeur, Raoul
- Subjects
- *
LEAF area index , *ECOSYSTEM management , *CULTIVARS , *PLANT development , *FOLIAGE plants , *PLANT canopies , *SHRUBS , *TUNDRAS , *BOTANICAL research , *REPRODUCTION - Abstract
Assimilation and exchange of carbon for arctic ecosystems depend strongly on leaf area index (LAI) and total foliar nitrogen (TFN). For dry–mesic tundras, the seasonality of these characteristics is unexplored. We addressed this knowledge gap by measuring variations of LAI and TFN at five contrasting subarctic heaths during the growing season 2007, from about 2 weeks after bud burst until about 2 weeks before senescence. The communities generally showed an early season LAI and TFN increase, owing to leaf development of deciduous shrubs, and limited variations later on, owing to concurrent leaf growth and mortality of evergreen shrubs. For most of the communities, the TFN:LAI ratio was constant along the entire sampling period, indicating that leaf growth and mortality, triggers for both LAI and TFN, are more important than leaf N retranslocation, which only affects TFN. A constant TFN:LAI ratio facilitates the determination of TFN from LAI, which is easier to measure or simulate. However, a sheltered community showed an increment in the LAI of the deciduous canopy in mid–late season, paralleled by a decreased TFN:LAI ratio. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
5. Relationships between leaf life span, leaf mass per area, and leaf nitrogen cause different altitudinal changes in leaf δ13C between deciduous and evergreen species.
- Author
-
Takahashi, K. and Miyajima, Y.
- Subjects
- *
CARBON , *PROXY statements , *GEOGRAPHY , *COSMOGRAPHY , *EARTH sciences , *GEOGRAPHIC names , *COUNTRIES , *CLIMATOLOGY , *GEOGRAPHY libraries - Abstract
We examined the variability in stable carbon isotope ratio (δ13C) in leaves of two deciduous broad-leaved species and two evergreen conifer species along an altitudinal gradient in central Japan. The δ13C of the two deciduous species decreased with altitude, except near the upper distribution limit. The two evergreen species, however, showed no clear altitudinal trends for δ13C. The δ13C of the two deciduous species was positively correlated with leaf mass per area (LMA), indicating that the altitudinal variation in δ13C was controlled by LMA. Leaf nitrogen per mass (as a proxy of assimilation capacity, Nmass) was negatively correlated with LMA for the two deciduous species, while it was not correlated with LMA for the two evergreen species. Leaf life span of the two deciduous species decreased with altitude, whereas that of the two evergreen species increased. Thus, the two deciduous species had shorter-lived thinner leaves with higher Nmass at higher altitudes, and the two evergreen species had longer-lived leaves. These changes contribute to the positive carbon balance at higher altitudes. Therefore, the different changes in δ13C with altitude between the deciduous and evergreen species are ascribed to the different altitudinal changes in the leaf traits for carbon balance. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
6. Post-harvest nitrogen cycling in clearcut and alternative silvicultural systems in a montane forest in coastal British Columbia.
- Author
-
Titus, Brian D., Prescott, Cindy E., Maynard, Doug G., Mitchell, Alan K., Bradley, Robert L., Feller, Michael C., Beese, W. J., Seely, Brad A., Benton, Ross A., Senyk, John P., Hawkins, Barbara J., and Koppenaal, Ross
- Subjects
SILVICULTURAL systems ,EXPERIMENTAL forests ,SOIL horizons ,ORGANIC compounds ,NITROGEN fixation ,NITROGEN compounds ,FORESTS & forestry ,FOREST management - Abstract
Copyright of Forestry Chronicle is the property of Canadian Institute of Forestry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2006
- Full Text
- View/download PDF
7. The biomass and nutrient levels of Calamagrostis canadensis and Carex stricta under different hydrologic and fungicide regimes.
- Author
-
Wetzel, Paul R. and van der Valk, Arnold G.
- Subjects
- *
PLANT growing media , *CALAMAGROSTIS , *CAREX , *FUNGICIDES , *HYDROLOGIC models , *BIOMASS - Abstract
We examined whether fungicide and the subsequent reduction of soilborne pathogenic fungi would differentially enhance the productivity and foliar nutrient content of two coexisting species, Calamagrostis canadensis (Michx.) Beauv. and Carex stricta Lam. This was tested under hydrologic regimes that simulated those in prairie wetlands and included a 32-d cycle (flooded 16 d, dry 16 d), 6-d cycle (flooded 3 d, dry 3 d), flooded, well-watered, and dry hydroperiods. Calamagrostis canadensis biomass increased 26%–45% in the wet hydroperiods (6-d cycle, well watered, and flooded) when fungicide was applied but remained fairly constant over all hydroperiods in nonfungicide treatments. Calamagrostis canadensis grown in the wet hydroperiods without fungicide produced the same biomass and growth rates as plants treated with fungicide in the dry hydrologic regime, suggesting that pathogenic fungi in wet hydrologic regimes have the same effect as major environmental stresses such as drought. In contrast, the biomass and growth rate of Carex stricta generally did not vary significantly with fungicide treatment. The only exception was in the rapidly alternating hydroperiod (6-d cycle), where Carex stricta treated with fungicide produced 48% more biomass and grew 46% faster than plants not treated with fungicide. Mean concentrations of foliar phosphorus generally were not significantly different between the fungicide and nonfungicide treatments for either plant species, while foliar nitrogen concentrations were higher in both species when treated with fungicide in the 32-d cycle, dry, and well-watered hydroperiods. The effect of fungicide on the biomass and foliar nutrients of these two co-occurring plant species depended on the species and the hydrologic regime, and our results suggest that seasonal and interannual changes in hydrologic regimes may confer a temporary advantage to one species or the other that, over the long term, allow them to coexist. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
- View/download PDF
8. Imagerie hyperspectrale et inférence de la teneur en azote foliaire: approche par modelisation pour documenter les effets liés à l'architecture de la plante
- Author
-
Roumet, Pierre, Jean, Pierre-Antoine, Gorretta, Nathalie, Rabatel, Gilles, Ecarnot, Martin, Amélioration génétique et adaptation des plantes méditerranéennes et tropicales (UMR AGAP), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro), Information – Technologies – Analyse Environnementale – Procédés Agricoles (UMR ITAP), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), and AGROCAMPUS OUEST. FRA.
- Subjects
modelling ,plant architecture ,Vegetal Biology ,teneur en azote ,[SDV.BV]Life Sciences [q-bio]/Vegetal Biology ,imagerie hyperspectrale ,azote foliaire ,Biologie végétale ,nitrogen content ,modélisation ,architecture de la plante - Abstract
La spectroscopie visible et proche Infrarouge couplée à de l’imagerie (hyperspectrale) permet le traitement du signal de réflectance à l’échelle d’un couvert végétal en plein champ. A partir de ce signal, un étalonnage permettant d'inférer la teneur en azote folaire d'un couvert de blé a été développé [1]. Notre objectif était de i) préciser le domaine de validité de cet étalonnage notamment en prenant en compte l'impact de variations architecturales (insertion des feuilles notamment) et ii) comprendre pourquoi les performances de l'étalonnage obtenu -au demeurant très correctes- restaient inférieures à celles obtenues sur feuilles ou plantes isolées. Nous avons modélisé différentes maquettes de couvert de blé (modèle architecturé ADEL [2]) correspondant à différents stades phénologiques et architectures folaires. Ces maquettes ont été couplées avec un modèle de radiosité, CARIBU, estimant la quantité d’énergie d’une feuille reçue soit directement soit par ses voisines (reflectances directe et multiples) [3]. Nous avons observé que les organes soumis à des expositions fortes (généralement situés dans la partie haute du couvert) présentaient peu de réflexions multiples et avaient une teneur en azote foliaire conforme à un attendu défini sur la base d'une feuille isolée. A l'inverse, les réflexions multiples étaient importantes pour les pixels situés dans la partie basse du couvert générant un découplage entre signal spectral et contenu bichimique et une sous estimation de la teneur en azote (-0.4 points). Ces résultats sont présentés dans différents contextes architecturaux et leurs implications sont discutées dans le cadre du développement de la technologie hyperspectrale pour l’inférence de la teneur azote foliaire de couvert de blé., Imaging coupled with visible and infrared spectroscopy provide us some data to represent the canopy under field conditions. This signal can be processed to infer some leaf biochemical content such as nitrogen [1]. Here our aim was firstly, to precise how this calibration could be extended to numerous architectural contexts according in particular to leaf angle and secondly, to clarify why the accuracy of this calibration is lower compared to another one's performed on isolated leaves. Using ADEL-wheat a 3d architectural model of wheat development [2], different scenes corresponding to wheat canopies along plant cycle or related to leaf geometry shape have been modelled. These 3D scenes have been coupled with Caribu which model lighting for virtual scenes [3] allowing to estimate in each point of the scene direct and multiple reflectances. Multiple reflexions were reduced for upper leaves which received larger amount of light whereas they were important for lower leaves decoupling the relationship between spectral data and leaf nitrogen content (LNC). Therefore the LNC of these leaves are slightly under-estimated (-0.4 points). The consequence of these results will be discussed in the frame of the use of hyperspectral imaging development for field phenotyping.
- Published
- 2015
9. A profiling approach of the natural variability of foliar N remobilization at the rosette stage gives clues to understand the limiting processes involved in the low N use efficiency of winter oilseed rape
- Author
-
Marie-Françoise Niogret, Philippe Etienne, Alain Bouchereau, Marine Poret, Jacques Trouverie, Carole Deleu, Laurent Leport, Jean-Christophe Avice, Françoise Le Cahérec, Mathilde Orsel, Alexandra Girondé, Ecophysiologie Végétale, Agronomie et Nutritions (EVA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Recherche Agronomique (INRA), Institut de Génétique, Environnement et Protection des Plantes (IGEPP), Institut National de la Recherche Agronomique (INRA)-Université de Rennes (UR)-AGROCAMPUS OUEST, Institut de Recherche en Horticulture et Semences (IRHS), Université d'Angers (UA)-Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Institut National de la Recherche Agronomique (INRA)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-AGROCAMPUS OUEST, Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), and AGROCAMPUS OUEST-Institut National de la Recherche Agronomique (INRA)-Université d'Angers (UA)
- Subjects
remobilisation de l'azote ,nitrogen nutrition ,Genotype ,Physiology ,Nitrogen ,[SDV]Life Sciences [q-bio] ,Plant Science ,Biology ,Protein degradation ,7. Clean energy ,nitrogen use efficiency ,chemistry.chemical_compound ,Nitrate ,Gene Expression Regulation, Plant ,[SDV.BV]Life Sciences [q-bio]/Vegetal Biology ,Natural variability ,Amino acid export ,nitrogen utilization efficiency ,soluble proteins ,Plant Proteins ,2. Zero hunger ,amino acids ,efficience d'utilisation de l'azote ,nitrogen remobilization efficiency ,genotypic variability ,Brassica napus ,Genetic Variation ,food and beverages ,protéine soluble ,Limiting ,azote foliaire ,nutrition azotée ,Plant Leaves ,Agronomy ,chemistry - Abstract
International audience; Oilseed rape, a crop requiring a high level of nitogen (N) fertilizers, is characterized by low N use efficiency. To identify the limiting factors involved in the N use efficiency of winter oilseed rape, the response to low N supply was investigated at the vegetative stage in 10 genotypes by using long-term pulse-chase (15)N labelling and studying the physiological processes of leaf N remobilization. Analysis of growth and components of N use efficiency allowed four profiles to be defined. Group 1 was characterized by an efficient N remobilization under low and high N conditions but by a decrease of leaf growth under N limitation. Group 2 showed a decrease in leaf growth under low N supply that was associated with a low N remobilization efficiency under both N supplies despite a high remobilization of soluble proteins. In response to N limitation, Group 3 is characterized by an increase in N use efficiency and leaf N remobilization compared with high N that is not sufficient to sustain the leaf biomass production at a similar level to non-limited plants. Genotypes of Group 4 subjected to low nitrate were able to maintain leaf growth to the same level as under high N. The profiling approach indicated that enhancement of amino acid export and soluble protein degradation was crucial for N remobilization improvement. At the whole-plant level, N fluxes revealed that Group 4 showed a high N remobilization in source leaves combined with a better N utilization in young leaves. Consequently, an enhanced N remobilization limits N loss in fallen leaves, but this remobilized N needs to be efficiently utilized in young leaves to improve N use efficiency.
- Published
- 2015
10. Propriétés spectrales d’un couvert de blé : relations entre l’architecture 3D et la réflectance du couvert
- Author
-
Jean, P. A., Ecarnot, Martin, Gorretta, N., Rabatel, Gilles, Roumet, Pierre, Institut National de la Recherche Agronomique (INRA), Amélioration génétique et adaptation des plantes méditerranéennes et tropicales (UMR AGAP), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Société Française de Photogrammétrie et Télédétection (SFPT). FRA., Information – Technologies – Analyse Environnementale – Procédés Agricoles (UMR ITAP), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and ProdInra, Migration
- Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences ,[SDV.SA] Life Sciences [q-bio]/Agricultural sciences ,modélisation architecturale ,couvert végétal ,modèle 3d ,[SDV]Life Sciences [q-bio] ,azote foliaire ,reflectance spectrale ,modèle mathématique ,blé ,[SDV.IDA]Life Sciences [q-bio]/Food engineering ,[SDV.BV]Life Sciences [q-bio]/Vegetal Biology ,[SDV.BV] Life Sciences [q-bio]/Vegetal Biology ,[SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering ,spectroscopie infra rouge ,imagerie hyperspectrale ,ComputingMilieux_MISCELLANEOUS - Abstract
National audience; La spectroscopie visible et proche infrarouge couplée à l’imagerie hyperspectrale permet le traitement du signal de réflectance à l’échelle d’un couvert végétal et le développement de relations de calibration destinées à déduire la composition chimique de ce couvert comme l’azote foliaire. Un modèle mathématique de détermination de l’azote a été mis en place à l’échelle du couvert en se basant sur l’imagerie hyperspectrale. Toutefois les interactions possibles entre données de réflectance du couvert et les propriétés architecturales (taille et angle d’insertion des feuilles) interrogent sur la robustesse du modèle obtenu. Pour préciser l’impact de ces variations architecturales sur les propriétés spectrales du couvert, nous avons modélisé différentes maquettes de couverts de blé (modèle architecturé ADEL) à différents stades phénologiques avec un modèle de radiosité imbriqué (calcul de la quantité d’énergie d’une feuille reçue par ses voisines) nommé Caribu. Ces deux modèles sont disponibles sur la plate forme Open Alea.27 L’analyse en composantes principales a été utilisée pour représenter les données issues de Caribu. Les deux premiers axes de cette ACP (> 99 % de la variabilité expliquée) représentent respectivement l’exposition de la feuille et les réflexions multiples. Le modèle azote a été appliqué à ces données spectrales. Pour une maquette donnée, nous avons pu observer que les organes soumis à des expositions fortes et ne présentant pas de réflexions multiples avaient une teneur en azote foliaire conforme à l’attendu alors que les triangles situés dans la partie basse du couvert, très soumise à des réflexions multiples, avaient une teneur en azote foliaire sous-estimée ( 0.4 points). Ces résultats sont présentés dans différents contextes architecturaux ; leurs implications sont discutées dans le cadre du développement de la technologie hyperspectrale pour l’estimation de la teneur en azote foliaire de couverts de blé.
- Published
- 2014
11. Reply to Ollinger et al.: Remote sensing of leaf nitrogen and emergent ecosystem properties
- Author
-
Yan Yang, Alexei Lyapustin, Anthony B. Davis, Vern C. Vanderbilt, Robert K. Kaufmann, Ranga B. Myneni, Alexander Marshak, Mitchell A. Schull, Pedro Latorre Carmona, Philip Lewis, Stéphane Jacquemoud, Yuri Knyazikhin, Pauline Stenberg, Matti Mõttus, Miina Rautiainen, Frédéric Baret, Mathias Disney, Department of Earth and Environment [Boston], Boston University [Boston] (BU), University College of London [London] (UCL), University of Helsinki, Department of Forest Sciences, University of Alaska [Fairbanks] (UAF), National Aeronautics and Space Administration, Partenaires INRAE, Hydrology and Remote Sensing Laboratory, US Department of Agriculture [Beltsville] (USDA), Universitat Jaume I, Jet Propulsion Laboratory (JPL), California Institute of Technology (CALTECH)-NASA, Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH), Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut de Physique du Globe de Paris (IPGP), and Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
- Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences ,feuille ,Canopy ,reflectance ,télédétection ,[SCCO.COMP]Cognitive science/Computer science ,écosystème ,03 medical and health sciences ,capteur optique ,Ecosystem properties ,spectroscopie proche infrarouge de réflectivité NIRS ,Radiative transfer ,transfert radiatif ,Ecosystem ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,Remote sensing ,azote ,0303 health sciences ,Multidisciplinary ,photon ,04 agricultural and veterinary sciences ,Canopy properties ,azote foliaire ,15. Life on land ,Inverse problem ,Computer science ,Reflectivity ,Agricultural sciences ,Geography ,13. Climate action ,Remote sensing (archaeology) ,Informatique (Sciences cognitives) ,spectre de reflectance ,040103 agronomy & agriculture ,0401 agriculture, forestry, and fisheries ,Leaf nitrogen ,mécanisme biologique ,donnée satellitaire ,Sciences agricoles ,structure de la canopée - Abstract
Various physical, chemical, and physiological processes, including canopy structure, impact surface reflectance. Remote sensing aims to derive ecosystem properties and their functional relationships, given these impacts. Ollinger et al. (1) do not distinguish between the forward and inverse problems in radiative transfer and, hence, misrepresent our results (2). The authors also suggest our conclusions are based on a subset of data from ref. 3, which is not the case.
- Published
- 2013
12. Modifications physiologique et protéomique associées à la remobilisation de l'azote foliaire au cours de la sénescence séquentielle chez le colza (Brassica Napus L.)
- Author
-
Desclos, Marie, Ecophysiologie Végétale, Agronomie et Nutritions (EVA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Recherche Agronomique (INRA), Université de Caen Basse Normandie, and Jean-Christophe Avice
- Subjects
fertilisation azotée ,privation d'azote ,[SDV]Life Sciences [q-bio] ,[SDE]Environmental Sciences ,inhibiteur de protéase ,these ,sénescence foliaire ,azote foliaire ,colza d'hiver - Abstract
Plante de grande culture, le colza (Brassica napus L. ) présente une faible efficience d’utilisation de l’azote (EUA) due à une mauvaise remobilisation de l’azote (N) au cours de la sénescence foliaire. Afin de caractériser les mécanismes clés susceptibles d’améliorer l’EUA, les objectifs visaient à identifier les processus physiologiques, protéomiques et moléculaires impliqués dans la remobilisation du N au cours de la sénescence foliaire et de déterminer l’impact de bas intrants azotés sur ces processus. Les jeunes feuilles de colza privées en nitrate présentent un ralentissement de la sénescence concomitant à l’accumulation d’un inhibiteur de protéases correspondant à BnD22 (Brassica napus Drought 22 kDa), une protéine capable de se lier aux chlorophylles. La double fonction de BnD22 interviendrait dans la protection des tissus juvéniles en maintenant l’intégrité des protéines et la capacité photosynthétique en réponse aux stress abiotiques. L’analyse des événements physiologiques et protéomiques associés à la remobilisation du N et à la sénescence foliaire a montré l’implication de protéines du métabolisme énergétique, de réponse aux stress et de protéolyse. Une protéase chloroplastidiale FtsH, une protéase à aspartate, une sous-unité du protéaosome et une protéase à cystéine SAG12 sont successivement induites au cours de la sénescence. La privation en N accélère l’entrée en sénescence mais n’affecte pas la séquence des événements. Le faible niveau de N résiduel observé dans les feuilles chutées de colzas privés en N s’explique par la conjonction d’une sénescence précoce, d’une protéolyse rapide, et d’une augmentation de la durée et de l’intensité du recyclage du N., Senescence, the faster proteolysis, and the increase of duration as well as intensity of N recycling. Brassica napus L. (oilseed rape) is an important crop plant with low nitrogen use efficiency (NUE) due to a weak remobilization of nitrogen (N) during leaf senescence. In order to characterize the key processes able to improve the NUE, the objectives were to identify the physiological, proteomics and molecular events implied in N remobilization during leaf senescence, and to determine whether low mineral N availability impact on these events. Young leaves of nitrate-deprived plants presented a delay of senescence concomitant with the accumulation of a trypsin inhibitor corresponding to BnD22 (Brassica napus Drought 22 kDa), a protein capable of binding chlorophylls. The dual function of BnD22 could be involved in the protection of younger tissues by maintaining protein integrity and photosynthesis capacity in response to abiotic stresses. The analysis of proteomics and physiological events associated with N remobilization and leaf senescence revealed the involvement of proteins acting in energy metabolism, plant stress response and proteolysis. A chloroplastidial protease FtsH, an aspartic protease, a proteaosome subunit and a cysteine protease SAG12 were successively induced during leaf senescence. The N starvation led to accelerate the onset of leaf senescence but did not affect the sequence of events. The weak level of residual N observed in fallen leaves of oilseed rape deprived in N was explained by the premature.
- Published
- 2008
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.