BANCAL Pierre.JPG

BANCAL Pierre

Chargé de Recherche : Répartition C/N chez le blé en remplissage

Chargé de Recherche : Répartition C/N chez le blé en remplissage

 

HAL : Dernières publications

  • [hal-03660399] Towards a global characterization of winter wheat cultivars behavior in response to stressful environments during grain-filling

    Starting from grain yield, quality and resistance against multiple diseases, the characterization of the cultivar’s behavior increased in recent decades. Needs in quantitative assessments of a larger range of criteria has greatly evolved towards yield stability in a large range of fluctuating environments. Using a large dataset crossing cultivars and environments, we thus explored the relationships between yield and Healthy Area Duration (HAD), as affected by genotype, environment and septoria caused by Zygmoseptoria tritici. A set of indexes was then proposed to properly profile cultivar’s behavior. A curvilinear relationship relating HAD to potential yield was first parameterized. It allows quantifying HAD efficiency. Susceptibility (HAD loss) was differentiated from total tolerance (the ratio between yield loss and HAD loss). Finally the specific tolerance, i.e. not due to HAD level, was quantified. Correlations between indexes pointed out that no trade-off was shown between total tolerance and actual or potential yield as well as disease susceptibility. These correlations partially depended on the nitrogen status of crops, underlining other G×E interactions indexes may trap. Finally, as HAD efficiency appeared more highly linked to actual yield than potential yield we proposed an alternative set on indexes based on Healthy Area Absorption (HAA) that accounted for meteorological variability. Interestingly, these last indexes were insensitive to nitrogen nutrition as well as to cultivar susceptibility to Z. tritici. The developed indexes allowed profiling the cultivars’ behavior under a common range of environments. HAA-based indexes open the way to a useful global characterization of cultivars by breeders. Moreover, HAA can be assessed using high-throughput phenotyping tools. A thorough evaluation of this last point needs to be done.

    ano.nymous@ccsd.cnrs.fr.invalid (Marie-Odile Bancal) 05 May 2022

    https://agroparistech.hal.science/hal-03660399
  • [hal-02947483] Green loss and nitrogen remobilization along the flag leaf blade of wheat

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 24 Sep 2020

    https://hal.inrae.fr/hal-02947483
  • [hal-01678092] Wheat lines exhibiting variation in tolerance of Septoria tritici blotch differentiated by grain source limitation

    Septoria tritici blotch (STB) is the most damaging disease of wheat crops in Europe. Because of the partial nature of genotypic resistance or the increasing resistance against fungicides, the tolerance, i.e. maintaining yield in the presence of expressed disease, is a relevant alternative. Tolerance is generally estimated through the yield loss per unit of source reduction, contrasts of tolerance between genotypes have been observed previously suggesting that either increasing the source availability or improving the use of stored assimilate could improve tolerance. This paper aims at developing a source/sink approach to understand the tolerance mechanism and identifying potential traits to increase tolerance of STB. A field experiment was designed to explore the relation between tolerance of STB and source/sink balance. Based on six wheat genotypes contrasting for tolerance exposed to natural STB epidemics, late nitrogen fertilization and a 50% spikelet removal were applied to change the source/sink balance. The tolerance of genotypes was quantitatively estimated over three additional field experiments. We found that STB tolerance was correlated with traits of healthy crops (high individual grain weight and high proportion of green leaf lamina area as leaf 3; flag leaf = leaf 1). The spikelet removal revealed a highly variable degree of source limitation for grain filling amongst the six genotypes. Thus, we proposed an easily calculated index that highly correlated positively with the labor intensive estimation of STB tolerance. Finally, potential yield and tolerance were not correlated, which suggests that breeding for yield performance and tolerance could be possible.

    ano.nymous@ccsd.cnrs.fr.invalid (François Collin) 08 Jan 2018

    https://hal.science/hal-01678092
  • [hal-02624328] Estimation of leaf traits from reflectance measurements: comparison between methods based on vegetation indices and several versions of the PROSPECT model

    Leaf biochemical composition corresponds to traits related to the plant state and its functioning. This study puts the emphasis on the main leaf absorbers: chlorophyll a and b (Cab), carotenoids (Cc), water (Cw) and dry mater (Cm) contents. Two main approaches were used to estimate [Cab, Cc, Cw, Cm] in a non-destructive way using spectral measurements. The first one consists in building empirical relationships from experimental datasets using either the raw reflectances or their combination into vegetation indices (VI). The second one relies on the inversion of physically based models of leaf optical properties. Although the first approach is commonly used, the calibration of the empirical relationships is generally conducted over a limited dataset. Consequently, poor predictions may be observed when applying them on cases that are not represented in the training dataset, i.e. when dealing with different species, genotypes or under contrasted environmental conditions. The retrieval performances of the selected VIs were thus compared to the ones of four PROSPECT model versions based on reflectance data acquired at two phenological stages, over six wheat genotypes grown under three different nitrogen fertilizations and two sowing density modalities. Leaf reflectance was measured in the lab with a spectrophotometer equipped with an integrating sphere, the leaf being placed in front of a white Teflon background to increase the sensitivity to leaf biochemical composition. Destructive measurements of [Cab, Cc, Cw, Cm] were performed concurrently.

    ano.nymous@ccsd.cnrs.fr.invalid (Jingyi Jiang) 26 May 2020

    https://hal.inrae.fr/hal-02624328
  • [hal-01739289] An innovative light chamber for measuring photosynthesis by three-dimensional plant organs

    Abstract Background: In plants, three-dimensional (3-D) organs such as inflorescences or fruits carry out photosynthesis and thus play a significant role in carbon assimilation and yield. However, this contribution has been poorly characterized because there is no reliable method for measuring photosynthesis by 3-D organs. One of the major challenges is ensuring the uniform irradiation of samples that are placed within a sealed chamber. Results: In this study, we developed an innovative chamber with homogeneous lighting that can be used to measure photosynthesis by large 3-D organs. It consisted of a 15-cm-long sealed transparent cylinder that was surrounded by a decagonal prismatic light source, made up of a mixture of red and blue LEDs. We characterized irradiance homogeneity within the chamber at a resolution level of 1 cm and 10°. Photosynthetic photon flux density (PPFD) along the central axis of the chamber could be set to any value between 100 and 1100 μmol m−2 s−1. The coefficient of variation for the irradiation values found throughout the chamber was 10% and that for the ratio of red-to-blue spectra was less than 1.5%. The temperature of the sample was regulated to stay within 1 °C of the target temperature, regardless of PPFD. We compared the performance of our device with that of a commercially available device employing unidirectional lighting. Specifically, we examined net photosynthesis in two sample types—wheat ears and grape clusters—at varying PPFD levels. Conclusions: The devices gave similar estimates of dark respiration, regardless of sample type or age. Conversely, net photosynthesis started to become asymptotic at lower irradiance levels in our device than in the conventional device because apparent quantum yield was three times higher. When examining the effects of irradiance heterogeneity, it was clear that biased estimates could result from systems employing unidirectional light sources. Our results also confirmed that our chamber could be a useful tool for obtaining more accurate estimates of photosynthesis by 3-D organs.

    ano.nymous@ccsd.cnrs.fr.invalid (Alain Fortineau) 20 Mar 2018

    https://hal.science/hal-01739289
  • [hal-02947495] Does Zymoseptoria tritici accelerate leaf apical senescence in winter wheat plants cv. Soissons grown under contrasted nitrogen conditions?

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 24 Sep 2020

    https://hal.inrae.fr/hal-02947495
  • [hal-02947494] Mise au point d’une chambre à éclairement cylindrique adaptée à la mesure de la photosynthèse par les organes massifs

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 24 Sep 2020

    https://hal.inrae.fr/hal-02947494
  • [hal-02947484] Impacts physiologiques et agronomiques de l’application d’une nouvelle spécialité fongicide en T2 sur des couverts de blé

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 24 Sep 2020

    https://hal.inrae.fr/hal-02947484
  • [hal-01370080] Zymoseptoria tritici development induces local senescence in wheat leaves, without affecting their monocarpic senescence under two contrasted nitrogen nutrition

    Zymoseptoria tritici causes large losses in wheat yield usually related to the losses of green area. However, the issue of whether green area losses result from the local necrosis or from acceleration in the monocarpic apical senescence remains open. The present study examined whether leaf inoculation with Zymoseptoria tritici modifies apical senescence of flag leaf in wheat cultivar Soissons grown under two contrasted nitrogen nutritions. The dynamics of local and apical senescences and the pycnidia number were measured repeatedly throughout the grain filling. Local and apical senescence were adjusted to functions, the parameters of which were analyzed according to nitrogen and inoculation treatments. The intra-leaf gradient of residual nitrogen concentration was measured at plant maturity. The relative rate of apical senescence increased twofold when fertilization was withheld. Both treatments, inoculation and nitrogen, generated a large range of disease that developed to different extents, resulting from different rates and timing. Local necrosis and pycnidia number strongly varied with nitrogen nutrition but necrosis varied in the same extent as apical senescence, thus green area relative loss was unaffected by nitrogen nutrition. By opposition, apical senescence was never affected at any time by the inoculation. Residual nitrogen increased in the inoculated portions of the infected leaves, in correlation with local necrosis, whereas the residual nitrogen in the non-inoculated part of infected leaves stayed at the level of control leaves. Apical senescence was managed at the leaf tissue level, according to nitrogen availability but regardless of disease, a useful output for modelling.

    ano.nymous@ccsd.cnrs.fr.invalid (Marie-Odile Bancal) 21 Sep 2016

    https://hal.science/hal-01370080
  • [hal-01535231] Identifying traits leading to tolerance of wheat to Septoria tritici blotch

    tIdentifying tolerance traits to diseases in wheat genotypes has an increased interest to minimize pesticideuse and to complement resistance and escape.Yield tolerance to Septoria tritici blotch (STB) was studied pooling up three experiments involving18 genotypes, 5 years and 6 sites in France, amounting to 161 genotype × year × site × managementcombinations. Each combination involves a crop pair (treated or not against foliar diseases) repeated twoto three times. Most crops were grown under high fertilization, and STB was the main disease present inuntreated crops. Crop traits (ear density, grain number and weight, area of leaf laminas) were recorded;green area of leaf laminas over time was fitted to a Gompertz equation, producing metrics for senescencetraits (time and duration).Over the whole dataset, LAI from 1.1 to 7.5 m2m−2; yields from 280 to 1122 gDM m−2and relative yieldlosses up to 70% were recorded. Fungicide treated crops exhibited slightly larger ear density and leaf lam-ina area independently of the intensity of epidemics. As an overall trend, yield became more determinedby source traits when epidemics occurred. Yield loss was proportional (r2= 0.7) to senescence advanceby disease. Decrease in grain number and weight were also correlated (r2= 0.4 and 0.8, respectively) toyield loss. Two epidemic indices were built to compare data across year × site combinations. Then yieldin untreated crop was predicted (r2= 0.87) from yield in corresponding treated crop, and interactionof epidemic indices with traits of the treated crops that therefore were pointed out as responsible fortolerance variability. Late senescing crops exhibited a greater tolerance to epidemics. Conversely, grainweight was a major key of intolerance. To minimize the trade-off between yield potential and toleranceit is thus suggested to maximize grain number.This study represents a first step in identifying key traits involved in tolerance to STB in varyingagronomic conditions and cultivars

    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 08 Jun 2017

    https://hal.science/hal-01535231
  • [hal-01192469] Tolérance du blé tendre aux stress biotiques et abiotiques

    Les divers stress biotiques et abiotiques qu'un peuplement rencontre au cours de son cycle ont souvent comme effet majeur la réduction de la surface foliaire verte. Des travaux préliminaires ont montré une certaine stabilité de la relation entre l’indice foliaire vert intégré pendant le remplissage du grain (IFVI) et le rendement. Ce projet avait pour objectif d'utiliser l'IFVI pour mettre au point un indicateur global de phénotypage "multistress", afin de caractériser le comportement variétal dans différents environnements et ITK. Il devait également approfondir la notion de tolérance, consistant au maintien des performances en présence de stress avéré, et jusqu'ici mal séparée du potentiel de rendement. En mobilisant des acteurs de la recherche (INRA, Lasalle), du développement (Arvalis) et du secteur privé (Saaten Union), une base de données importante a été construite. Les résultats de stations expérimentales ont permis l’élaboration de l’indicateur, tandis que son automatisation "haut débit" était travaillée par ailleurs. Le réseau INRA "ITK blés rustiques" a permis l'évaluation de l'ensemble. On distinguera une tolérance intrinsèque, qui ne dépend que du niveau d’IFVI, donc du potentiel de la culture, et une tolérance spécifique, réponse variétale à un changement de milieu ou d'ITK. Potentiel et rusticité sont largement indépendants, et peuvent donc être sélectionnés conjointement. Par contre notre base de données suggère un trade-off entre les composantes de la rusticité: tolérance, et résistance + échappement, soulignant le besoin de recherche dans ce domaine. A terme, l'indicateur proposé pourra être utilisé pour caractériser les variétés les plus adaptées à un milieu donné et pour aider à la conception de couverts de céréales écologiquement intensifs.

    ano.nymous@ccsd.cnrs.fr.invalid (D. Gouache) 27 May 2020

    https://hal.science/hal-01192469
  • [hal-01000864] Crop architecture and crop tolerance to fungal diseases and insect herbivory. Mechanisms to limit crop losses

    Plant tolerance to biotic stresses (mostly limited here to fungal pathogens and insects) is the ability of a plant to maintain performance in the presence of expressed disease or insect herbivory. It differs from resistance (the capacity to eliminate or limit pests and pathogens by genetic and molecular mechanisms) and avoidance (the ability to escape infection by epidemics). The ways to tolerance of pests and diseases are multiple and expressed at different scales. The contribution of organs to the capture and use of resources depends on canopy and root architecture, so the respective locations of disease and plant organs will have a strong effect on the crop's response. Similarly, tolerance is increased when the period of crop sensitivity lies outside the period within which the pest or pathogen is present. The ability of the plant to compensate for the reduced acquisition of resources by the production of new organs or by remobilization of reserves may also mitigate biotic stress effects. Numerous examples exist in the literature and are described in this article. Quantification of tolerance remains difficult because of: (i) the large number of potential mechanisms involved; (ii) different rates of development of plants, pests and pathogens; and (iii) various compensatory mechanisms. Modelling is, therefore, a valuable tool to quantify losses, but also to prioritize the processes involved

    ano.nymous@ccsd.cnrs.fr.invalid (Bertrand B. Ney) 04 Jun 2014

    https://hal.science/hal-01000864
  • [hal-01000853] Down-regulation by stems and sheaths of grain filling with mobilized nitrogen in wheat

    A major challenge for modern agriculture is to limit the excessive use of chemicals while improving wheat grain quality, mainly protein concentration, but without affecting yield. This paper focuses on the regulation of N mobilization from vegetative organs to fill the grains. Wheat crops were grown at low N uptake post anthesis. Ten days after anthesis, the second and third upper leaf blades were either cut at the ligule or wrapped in aluminium foil. The evolution of chlorophyll, green area, dry matter and N was studied in all organs from anthesis to maturity. N related metabolites (proteins, amino acids, nitrate) and enzymatic activities (glutamine synthetase, glutamate dehydrogenase, nitrate reductase, endoprotease) were also assessed in the blades. The grain N filling immediately slowed down following the defoliation by the same extent as the N mobilization rate from cut blades, while no modification of senescence or N metabolism occurred in other vegetative parts. In contrast, all indices for N metabolism indicated that wrapped blades exhibited strongly accelerated senescence. N was then completely released from these organs within two weeks, thus temporarily increasing N availability for the rest of the plant. However, no difference in grain N was observed between shoots with wrapped leaves and controls, whereas stem and sheaths stored the extra N released by wrapped blades. Grains did not adjust their N filling rate to N mobilization rate. Instead, the rate for N filling was asymmetrically regulated by the stem and/or sheaths. Lowering the N mobilization rate immediately resulted in a lower rate for grain N filling, whereas increasing N mobilization did not change the rate of grain N filling, due to temporary storage.

    ano.nymous@ccsd.cnrs.fr.invalid (Rym R. Ben Slimane) 04 Jun 2014

    https://hal.science/hal-01000853
  • [hal-01004328] Crop Architecture and Crop tolerance to biotic stresses. Mechanisms to limit crop losses

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    ano.nymous@ccsd.cnrs.fr.invalid (J. J. Smith) 11 Jun 2014

    https://hal.science/hal-01004328
  • [hal-01003422] Modelling fungal sink competitiveness with grains for assimilates in wheat infected by a biotrophic pathogen

    Experiments have shown that biotrophic fungi divert assimilates for their growth. However, no attempt has been made either to account for this additional sink or to predict to what extent it competes with both grain filling and plant reserve metabolism for carbon. Fungal sink competitiveness with grains was quantified by a mixed experimentalmodelling approach based on winter wheat infected by Puccinia triticina. One week after anthesis, plants grown under controlled conditions were inoculated with varying loads. Sporulation was recorded while plants underwent varying degrees of shading, ensuring a range of both fungal sink and host source levels. Inoculation load significantly increased both sporulating area and rate. Shading significantly affected net assimilation, reserve mobilization and sporulating area, but not grain filling or sporulation rates. An existing carbon partitioning (sourcesink) model for wheat during the grain filling period was then enhanced, in which two parameters characterize every sink: carriage capacity and substrate affinity. Fungal sink competitiveness with host sources and sinks was modelled by representing spore production as another sink in diseased wheat during grain filling. Data from the experiment were fitted to the model to provide the fungal sink parameters. Fungal carriage capacity was 056 001 g dry matter Cd-1 per lesion, much less than grain filling capacity, even in highly infected plants; however, fungal sporulation had a competitive priority for assimilates over grain filling. Simulation with virtual crops accounted for the importance of the relative contribution of photosynthesis loss, anticipated reserve depletion and spore production when light level and disease severity vary. The grain filling rate was less reduced than photosynthesis; however, over the long term, yield loss could double because the earlier reserve depletion observed here would shorten the duration of grain filling. Sourcesink modelling holds the promise of accounting for plantpathogen interactions over time under fluctuating climatic/lighting conditions in a robust way.

    ano.nymous@ccsd.cnrs.fr.invalid (Marie-Odile Bancal) 10 Jun 2014

    https://hal.science/hal-01003422
  • [hal-01000795] Localized Septoria leaf blotch lesions in winter wheat flag leaf do not accelerate apical senescence during the necrotrophic stage

    Mycosphaerella graminicola, the most damaging disease of wheat in Northern Europe induces yield or grain quality losses usually related to green area losses. This work aims at clarifying whether induced senescence is due to an acceleration of apical senescence and thus to a modification of the leaf nitrogen remobilization rate. The effect on apical leaf senescence of a restricted diseased leaf area was investigated. The experiment involved four winter wheat cultivars varying in their susceptibility to four M. graminicola isolates. Flag leaves were inoculated at a dose representative of field epidemics. As soon as symptoms appeared, dynamics of apical senescence (Sapi) and around the inoculation zone (Ssep) were measured by repeatedly taking digital photos until senescent areas merged. Ssep trends were fit to a logistic function whose parameters depended on cultivar×isolate interactions. Disease severities ranged from 0 to 24% total leaf area. Apical senescence followed an exponential pattern in control and inoculated leaves. Sapi was twice as great in inoculated shoots as in controls, even when no disease occurred. The relative rate of Sapi depended on the cultivar, but no isolate effect was detected despite wide variations in Ssep extent. Paired comparisons between inoculated and control leaves showed that the relative rate of Sapi was not increased by inoculation. It is concluded, that over a wide range of Septoria disease, apical senescence was not accelerated in inoculated leaves as compared to control. Results suggest that the disease did not modify the regulation of leaf N remobilization rate.

    ano.nymous@ccsd.cnrs.fr.invalid (Rym R. Ben Slimane) 04 Jun 2014

    https://hal.science/hal-01000795
  • [hal-02947486] Tolérance du blé tendre aux stress biotiques et abiotiques » C2008-02 Blé tendre

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 24 Sep 2020

    https://hal.inrae.fr/hal-02947486
  • [hal-02947485] Septoria tritici: Une première approche de la tolérance aux stress de fin de cycle

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    ano.nymous@ccsd.cnrs.fr.invalid (David Gouache) 24 Sep 2020

    https://hal.inrae.fr/hal-02947485
  • [hal-01192243] A general cultivar tolerance to stresses and its modeling in the case of wheat affected by STB (Septoria tritici)

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 02 Sep 2015

    https://hal.science/hal-01192243
  • [hal-01192276] Impact of Septoria disease on apical senescence in wheat

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    ano.nymous@ccsd.cnrs.fr.invalid (Rym Ben Slimane) 02 Sep 2015

    https://hal.science/hal-01192276
  • [hal-01192198] Modélisation des interactions épidémie - couvert végétal : De la recherche à la mise au point d'outils opérationnels pour la protection intégrée des cultures

    La complexité des interactions entre les maladies et les couverts végétaux rend difficile la prise en compte de nombreux facteurs influençant celles-ci. Cette complexité limite l'élaboration d'outils fiables d'aide à la décision, la conception d’itinéraires techniques freinant les maladies, et l’évaluation variétale. Un projet collaboratif entre Arvalis et l’UMR EGC (INRA AgroParisTech), a permis d'élaborer des outils opérationnels, stables, fondés sur la compréhension des relations entre couvert et maladie, prenant la septoriose du blé comme "modèle" dans le cadre de l’Unité Mixte de Technologie Pivert. Ce projet repose sur un cadre conceptuel commun identifiant et hiérarchisant les différents points-clés des interactions entre épidémie et couvert. Les résultats, et la démarche, sont déclinés dans cette communication, et présentés en détail dans les posters auxquels il est fait référence.

    ano.nymous@ccsd.cnrs.fr.invalid (D. Gouache) 02 Sep 2015

    https://hal.science/hal-01192198
  • [hal-01192275] Dry matter partitioning parameterization in wheat infected by sporulating wheat leaf rust (Puccinia triticina)

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    ano.nymous@ccsd.cnrs.fr.invalid (Marie-Odile Bancal) 02 Sep 2015

    https://hal.science/hal-01192275
  • [hal-01192283] Regulation of grain N accumulation in wheat

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    ano.nymous@ccsd.cnrs.fr.invalid (Rym Ben Slimane) 02 Sep 2015

    https://hal.science/hal-01192283
  • [hal-02947482] Modélisation des interactions épidémie – couvert végétal : de la recherche à la mise au point d’outils opérationnels pour la protection intégrée des cultures

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 24 Sep 2020

    https://hal.inrae.fr/hal-02947482
  • [hal-01192125] Early development and enlargement of wheat floret primordia suggest a role of partitioning within spike to grain set

    Spike grain number, a major component in the yield of wheat, is suspected of being determined by the sudden death of most of the initiated floret primordia, which occurs at around booting. By counting twice weekly the number of floret primordia in the middle and top spikelets, the onset time for the death of floret primordia (Td) was assessed in six genotypes of differing earliness and fertility subjected to three treatments that were applied during stem elongation. The variation in Td was positively correlated with overall earliness, as well as with spike fertility. Ovary development and enlargement were quantified in eight specified positions within the spikes, but Td could not be assigned to a developmental stage attained by any ovary. Development and enlargement were very strongly correlated with each other throughout the floret lifetime, yet with significant effects of genotype, treatment and position within spikes. In each position within a spike, the proportion of florets that set a grain correlated to the initial delay of development as compared to the most advanced floret (r2 = 0.64), but this correlation was severely biased by genotype and the floret position effect. Better correlations were obtained with either the development or width of each ovary at Td, thus highlighting the role of the preceding phase. The best prediction (r2 = 0.93) was obtained from the ratio of ovary width to that of the most advanced floret at Td. The importance of this width ratio emphasized the role of partitioning in grain set: only florets able to divert nutrients survived after Td and eventually set a grain. This relationship was no longer biased by floret position, while some remaining variability due to genotype suggested potential for plant breeding: width ratios at Td were generally related to the growth duration of various primordia, as well as to their relative growth rate.

    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 02 Sep 2015

    https://hal.science/hal-01192125
  • [hal-01192050] Decorrelating source and sink determinism of nitrogen remobilization during grain filling in wheat

    Nitrogen (N) remobilization is the major source of N for grain filling in wheat, the other being N uptake after anthesis (Nup); however, variations in remobilization efficiency are not fully understood. It is hard to tell whether the source or the sink effects predominate, because N in the culm at anthesis (Nant) correlates strongly with both N remobilization (Nrem) and grain number (Gn), respectively the main source and the main sink. Methods: A pot experiment was thus designed to assess the relative contributions of the source and sink to Nrem regulation. Using two cultivars of winter wheat (Triticum aestivum, ‘Apache’ and ‘Autan’), three pre-anthesis and two post-anthesis N fertilization levels were applied in order to vary the N sources, while ear trimming at anthesis reduced sink size. Unlike results observed at a scale of m2, the equation binding Nant to Nrem exhibited a negative intercept, challenging the concept of nitrogen remobilization efficiency. Before ear trimming, Gn fitted well to Nant, with a slope dependent on genotype. To obtain a sink variable that was less correlated with Nant, the difference {delta}Gn was calculated between actual grain number and that which could be predicted from culm N before trimming. A multiple regression then predicted Nrem (r2 = 0·95) from Nant, Nup and {delta}Gn, with fitting unbiased by fertilization treatment, trimming or genotype. Conclusions: In untrimmed culms, {delta}Gn had a negligible effect, so that Nrem could be fitted to Nant and Nup only: grain N filling appeared to be determined by sources only (Nant and Nup), not by sink, and the reduction of Nrem by Nup was quantified. In these ‘normal’ cases, the regulation of Nrem should thus be located within the N sources themselves. In contrast, ear-trimming needs to be considered with caution as it introduced a sink limitation on Nrem; moreover one with an important genotype effect.

    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 02 Sep 2015

    https://hal.science/hal-01192050
  • [hal-01191988] Positive contribution of stem growth to grain number per spike in wheat

    This paper challenges the common belief that spike:stem competition determines grain number in wheat. A field experiment was conducted using three contrasting treatments (high shoot density, shading, and extended photoperiod) and six genotypes of varying earliness and spike:stem ratio. Floret primordia were counted in medium and top spikelets of main spikes throughout stem elongation. Floret death occurred simultaneously in both spikelets, and the corresponding critical time was used for comparison with growth analysis. Whole shoot growth rate was highest at the time of floret death, but both stem and spike growth continued to accelerate for a period of time thereafter. Spike respiration measurements did not indicate special requirements at the critical time. Spike carbohydrate concentration started to decline more or less before floret death, depending on genotype, but exactly at the inflexion time for spike elongation, thus suggesting a developmental process rather than a trophic limitation. Multiple correlation indicated that grain number positively correlated not only with spike growth rate at the time of floret death, but with both growth rates of spike and non-spike (stem + leaves) shoot parts. Grain number was poorly predicted by partitioning to spike of either shoot dry mass or shoot growth rate at critical time. In contrast, floret surviving proportion was highly correlated to partitioning and multiple correlation did not indicate a significant effect on survival of non-spike growth rate. It is concluded that even though spike:stem competition decreased floret survival, it was only loosely correlated to grain number.

    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 02 Sep 2015

    https://hal.science/hal-01191988
  • [hal-01192195] Late foliar diseases in wheat crops decrease nitrogen yield through N uptake rather than through variations in N remobilization

    Background and Aims French wheat grains may be of little value on world markets because they have low and highly variable grain protein concentrations (GPC). This nitrogen-yield to yield ratio depends on crop nitrogen (N) fertilization as well as on crop capacity to use N, which is known to vary with climate and disease severity. Here an examination is made of the respective roles that N remobilization and post-anthesis N uptake play in N yield variations; in particular, when wheat crops (Triticum aestivum) are affected by leaf rust (Puccinia triticina) and Septoria tritici blotch (teleomorph Mycosphaerella graminicola). Methods Data from a 4-year field experiment was used to analyse N yield variations in wheat crops grown either with a third or no late N fertilization. Natural aerial epidemics ensured a range of disease severity, and fungicide ensured disease-free control plots. The data set of Gooding et al. (2005, Journal of Agricultural Science 143: 503-518) was incorporated in order to enlarge the range of conditions. Key Results Post-anthesis N uptake accounted for a third of N yield whilst N remobilization accounted for two-thirds in all crops whether affected by diseases or not. However, variations in N yield were highly correlated with post-anthesis N uptake, more than with N remobilization, in diseased and also healthy crops. Furthermore, N remobilization did not significantly correlate with N yield in healthy crops. These findings matched data from studies using various wheat genotypes under various management and climatic conditions. Leaf area duration ( LAD) accurately predicted N remobilization whether or not crops were diseased; in diseased crops, LAD also accurately predicted N uptake. Conclusions Under the experimental conditions, N yield variations were closely associated with post-anthesis N uptake in diseased but also in healthy crops. Understanding the respective roles of N uptake and N remobilization in the case of diseased and healthy crops holds the promise of better modelling of variations in N yield, and thus in GPC.

    ano.nymous@ccsd.cnrs.fr.invalid (Marie-Odile Bancal) 02 Sep 2015

    https://hal.science/hal-01192195
  • [hal-02677383] Source-sink partitioning. Do we need Münch?

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 31 May 2020

    https://hal.inrae.fr/hal-02677383
  • [hal-02706642] Sucrose : fructan 6-fructosyltransferase, a key enzyme for diverting carbon from sucrose to fructan in barley leaves.

    [...]

    ano.nymous@ccsd.cnrs.fr.invalid (Nathalie Duchateau) 01 Jun 2020

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 01 Jun 2020

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    ano.nymous@ccsd.cnrs.fr.invalid (Pierre Bancal) 01 Jun 2020

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Date de modification : 06 novembre 2023 | Date de création : 04 août 2010 | Rédaction : Com Ecosys - S. Formisano