WorldCat Identities

Regnard, Jean-Luc

Overview
Works: 12 works in 12 publications in 2 languages and 19 library holdings
Roles: Contributor, Other, Author, Opponent, Thesis advisor
Publication Timeline
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Most widely held works by Jean-Luc Regnard
ROLE DE L'ANOXIE DANS LA LEVEE DE DORMANCE DES BOURGEONS DE PEUPLIER (POPULUS X EURAMERICANA (DODE) GUINIER, CV. I 214) : ANALYSE DES PROCESSUS PHYSIOLOGIQUES by Jean-Luc Regnard( Book )

1 edition published in 1984 in French and held by 3 WorldCat member libraries worldwide

L'ETUDE DE LA DORMANCE DES BOURGEONS DU PEUPLIER UTILISE LA MODELISATION DES BOUTURES DE NOEUDS ISOLES, APPRECIANT LE DEBOURREMENT PAR DIFFERENTS CRITERES CLASSIQUES (DD50, TMD, TMD) OU SPECIFIQUEMENT DEFINIS (DM30), DONT LA CORRELATION A ETE CONFIRMEE AU NIVEAU MICROMETRIQUE. L'ANOXIE TEMPORAIRE OU L'HYPOXIE INTENSE (MOINS DE 1% D'OXYGENE) ELIMINANT LA DORMANCE QUELLE QUE SOIT SON INTENSITE INITIALE. CET EFFET S'EXERCE A TOUTES LES TEMPERATURES, INDEPENDAMMENT DE L'ACTION DU FROID. L'EXAMEN DU MECANISME MET EN CAUSE L'ACTION DES PHENOLS OXYDABLES, DU PROCESSUS FERMENTAIRE INDUIT, ET LE ROLE JOUE PAR L'ETHYLENE SYNTHETISE CONSECUTIVEMENT AU TRAITEMENT. L'INTERVENTION DE L'ETHYLENE OU DE SON PRECURSEUR ACC ACCUMULE EN ANOXIE ET CONTRARIEE PAR LES INHIBITEURS SPECIFIQUES (AVG, CO**(++), AG**(+))
Field phenotyping of water stress at tree scale by UAV-sensed imagery: new insights for thermal acquisition and calibration by David Gómez-Candón( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

Are the effects of winter temperatures on spring budburst mediated by the bud water status or related to a whole-shoot effect? Insights in the apple tree by Juliano Dutra Schmitz( )

1 edition published in 2014 in English and held by 2 WorldCat member libraries worldwide

Genetic variability and phenotypic plasticity of apple morphological responses to soil water restriction in relation with leaf functions and stem xylem conductivity by Pierre-Éric Lauri( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

Evaluation of wild tomato accessions (Solanum spp.) for resistance to two-spotted spider mite (Tetranychus urticae Koch) based on trichome type and acylsugar content by Mohamed Rakha( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

Variabilité génétique de la tolérance à la sécheresse d'arbres d'intérêts agronomiques : rôle de la vulnérabilité à la cavitation du xylème by Wanploy Jinagool( )

1 edition published in 2015 in English and held by 1 WorldCat member library worldwide

In a context of climatic changes, drought stress and water management are regarded as one of the most important constraints for agricultural sector. Thus the selection for drought tolerance became a main objective for many breeding programs. Vulnerability to cavitation is considered a trait of interest for the selection for extreme drought stress, especially for woody species. However, the extent of its variability and its relation to drought tolerance are poorly documented on intraspecific level, particularly for cultivated species. In this study the genetic variability of vulnerability to cavitation was studied on three different experimental devices with three trees of agronomic interest that are threatened by the risk of drought: walnut, rubber and apple trees. Low or no variation in xylem vulnerability to cavitation was found in the studied species and between two species of walnuts despite differences previously reported features. These results suggested a canalization of cavitation resistance on critical organs (branches and stems). In apple tree, the rootstock was suspected to cause the narrow resistance to cavitation on the scion. On the contrary, differences on other traits in response to drought stress such as stomatal regulation, leaf shedding or vulnerability to cavitation on petiole were found. Therefore, vulnerability to cavitation of critical organs was not a relevant parameter for the selection of drought tolerance and breeding programs on the species studied did not appear to affect this parameter
Bases génétiques de la résistance vis-à-vis des nématodes du genre Meloidogyne chez le piment by Arnaud Barbary( )

1 edition published in 2014 in French and held by 1 WorldCat member library worldwide

Root-knot nematodes (RKNs), Meloidogyne spp., are extremely polyphagous plant parasites worldwide. Since the use of most chemical nematicides is being prohibited, genetic resistance is an efficient alternative way to protect crops against these pests. However, nematode populations proved able to breakdown plant resistance, and genetic resources in terms of resistance genes (R-genes) are limited. Sustainable management of these valuable resources is thus a key point of R-gene durability. In pepper, Me1 and Me3 are two dominant major R-genes, currently used in breeding programs to control M. arenaria, M. incognita and M. javanica, the three main RKN species. Challenging these two genes in different genetic backgrounds against M. incognita demonstrated that (1) the efficiency of the R-genes in reducing the reproductive potential of RKNs is strongly affected by the plant genetic background, (2) the allelic status of the R-genes has no effect on nematode reproduction. According to these first results, a QTL analysis was performed to identify and to localize partial resistance factors against RKNs which could explain the differences observed between the genetic backgrounds. Focusing on M. incognita, M. arenaria and M. javanica, four new major QTLs were localized. They are all regrouped on pepper chromosome P1 except one QTL efficient against M. javanica, which was located on pepper chromosome P9. The cluster on chromosome P1, regrouping most of the newly discovered resistance factors, is described for the first time with respect to RKN resistance. As a conclusion, this work should contribute to the breeding of new pepper varieties with a high level of resistance against RKNs
Analyse des interactions entre les racines d'hévéa (Hevea brasiliensis Muel. Arg.) et de cultures intercalaires dans les jeunes plantations du Nord-Est de la Thaïlande by Santimaitree Gonkhamdee( )

1 edition published in 2010 in English and held by 1 WorldCat member library worldwide

Pour d'évidentes raisons agronomiques et environnementales, être en mesure de concevoir et mettre en place des systèmes de culture dans lesquels les plantes accèdent aux ressources de manière optimale revêt une importance cruciale pour tous les intervenants impliqués dans la production agricole. Les techniques d'intensification telles que la mise en place de cultures d'inter-rang et l'agro-foresterie visent à accroître la productivité globale des terres tout en assurant la durabilité des agro-écosystèmes, via une optimisation de l'utilisation des ressources environnementales (lumière, eau et nutriments) par les plantes et une préservation des cycles géochimiques. En théorie, les moyens d'atteindre ces objectifs sont nombreux mais en pratique, les interactions souterraines sont complexes et difficiles à mesurer, de sorte que les progrès réalisés dans la conception d'agro-écosystèmes améliorés et durables demeurent modestes. Dans ce contexte, l'objectif de ce travail a été d'évaluer, au travers de mesures racinaires detaillées en rhizotron et au champ, les effets des cultures d'inter-rang sur la croissance des jeunes hévéas. La dynamique des interactions souterraines a été étudiée, tant au niveau de la racine individuelle qu'à celui du système racinaire entier, sur la base, notamment, de descriptions numériques détaillées. Une telle approche a permis de proposer, en outre, une voie novatrice pour l'analyse de la dynamique racinaire à l'echelle du systeme racinaire entier, à savoir l'analyse des trajectoires de croissance. Dans le cas de l'association maïs-hévéa, les expérimentations en rhizotron ont permis de mettre en evidence que les interactions souterraines entre ces deux plantes peuvent induire des modifications de la croissance de leurs racines, à la fois à l'échelle de la racine individuelle et à celle du système racinaire entier. Toutefois, une telle coordination des dynamiques racinaires des plantes associées n'a pas pu être confirmée dans le cas des traitements manioc-hévéa et arachide- hévéa. Les expérimentations au terrain ont fourni, de manière assez prévisible, une image complexe des interactions souterraines entre hévéa et cultures d'inter-rang. Toutefois, un premier résultat obtenu par le biais de la mise en place de 'pièges à racines' dans un traitement niébé-hévéa, a été de montrer que ces deux plantes n'avaient pas un comportement compétitif marqué l'une vis-à-vis de l'autre. Il est également apparu que les hévéas paraissent 'investir' dans des racines 'coûteuses', car de faible longueur spécifique, probablement pour assurer une certaine durabilité de ces organes, tandis que les cultures d'inter-rang favorisent l'allocation des assimilâts vers des racines de longueur spécifique élevée, de construction moins 'coûteuses', probablement en réponse a un impératif de croissance plus rapide (suggéré par les taux d'élongation racinaire mesurés au cours des expérimentations en rhizotron). Enfin, excepté le cas du manioc, l'introduction de cultures d'inter-rang telles que le maïs et l'arachide n'a pas eu d'impact significatif sur le développement des jeunes hévéas, comme en attestent l'évolution de leur circonférence, hauteur et développement foliaire. Ce résultat de terrain est compatible avec les résultats des expérimentations en rhizotron qui n'ont démontré aucun effet inhibiteur des cultures d'inter-rang sur le développement de la partie aérienne des hévéas. Bien que les travaux présentés dans ce rapport, ne permettent pas, à eux seuls de conclure de manière définitive sur la façon dont les espèces cultivées en association peuvent se compléter mutuellement sur le plan fonctionnel, ils apportent des éléments de réponse préliminaires à cette question complexe ainsi que des méthodes permettant de les obtenir. Au total, ce travail représente donc une contribution à la conception des agro-écosystèmes durables qui deviennent de plus en plus indispensables dans le contexte d'une demande mondiale croissante en produits alimentaires et matières premières. En outre, certains des résultats obtenus dans le cadre de cette thèse ouvrent des perspectives pour des recherches plus approfondies, avec une finalité agronomique appliquée
Variabilité architecturale et fonctionnelle du système aérien chez le pommier (Malus domestica Borkh.) : comparaison de quatre cultivars par une approche de modélisation structure-fonction by Catherine Massonnet( Book )

in French and held by 1 WorldCat member library worldwide

Beyond the well-described architectural diversity between apple tree cultivars, a functional variability is suspected, still scarcely investigated, which could affect their productivity and adaptation potential. ln other respects, it has been assurned that functional variability of different apple cultivars considered at an integrated scale could depend on the architectural organization of the aerial system and on the variability of foliage functions. The comparison which was here carried out between genotypes inc1uded 4 apple cultivars: Fuji and Braeburn, on the one hand, and Ariane and X3305, on the other hand. The trees were respectively 7-years-old and 2-years-old at the beginning of this study. Trees were cultivated in an experimental orchard which was irrigated and submitted to standard professional praètice. Between-trees study of the architectural variability revealed different dynamics of foliage setting between younger and older trees. Sorne differences in shoot composition were also revealed between trees of the same age, resulting in different light interception efficiency which was quantified by the STAR parameter (Silhouette to Totalleaf Area Ratio). A method for tree 3D-structure description was validated, which used a mixed approach of foliage digitalization and reconstruction. Functional comparison at the leaf scale showed that parameters of stomatal regulation (Jarvis model) differed between the 4 genotypes, while photosynthetic parameters (biochemical model of Farquhar) showed little variation. Architectural and functional characteristics of each cultivar were taken into account to parameterize and apply the RATP functional-structural model, and their coupling made it possible to simulate light interception capacity, transpiration and carbon gain at the branch scale. A sensitivity analysis of the model was applied to the Braeburn cultivar; it showed that architectural traits predominate when functional variability is considered at the branch scale. The research prospects opened by this ecophysiological approach applied to the apple tree by means of a functional-structural model are discussed
How can peach quality be promoted and brown rot prevented through coordinated agricultural practices and storage conditions? : a modeling approach by Enrico-Maria Casagrande( )

1 edition published in 2021 in English and held by 1 WorldCat member library worldwide

Peach quality development and fungal infections after harvest are issues of concern in the fruit value chain. Their examination would benefit from an integrated approach that considers the processes involved, their interactions, and their drivers. In this context, the general objectives of the thesis were (i) to create a modeling framework to simulate peach quality development and brown rot infections and their control by pre-harvest (cultural practices) and post-harvest (storage) conditions; and (ii) to use this model to investigate ways to improve fruit quality and to reduce losses. In this study, we focused on the nectarine (Prunus persica var. nucipersica) case. We first defined and calibrated, using experimental data, a mathematical model to simulate the combined effect of fruit growth and storage conditions (temperature and relative humidity) on nectarine quality-related traits. We modeledthe seasonal course of fruit surface conductance to water vapor, fruit mass loss during storage, and sugar concentration dynamics in fruit pulp. The observed data suggested an increase of sweetness with an increase of fruit mass loss during storage, which was also shown by model simulations. Moreover, the model put forward that fruit from late harvest dates could have higher sweetness at the end of storage than fruit harvested earlier. Second, we studied the spread of brown rot during storage. We verified experimentally that there were no secondary infections (without direct contact between fruit) by Monilinia laxa. Then, we used experimental results to test the effect of pre-harvest (including meteorology) and post-harvest conditionson the time-to-infection by brown rot, using a survival model with parametric estimates. Several conditions were found to be significant in explaining the disease incidence, notably the mean storage temperature, the fruit mass and the prevalence of brown rot at harvest, and the mean wetness duration in the week before harvest. Finally, we integrated the above-mentioned models within a fruit crop model that takes explicitly into account the role of pre-harvest practices on the development of fruit characteristics at the tree scale. We studied, via a sensitivity analysis and model exploration, the model behavior in relation to some orchard practices (irrigation and fruit load) and storage conditions (temperature and relative humidity). Model simulations correctly reproduced the well-known effects of practices on fruit quality criteria, such as the increase of fruit size under well-irrigated conditions and low fruit load, and the increase of sweetness under water-stressed regimes. The model was able to support that fruit properties are controlled by storage conditions, notably fruit mass loss increases with increasing temperature and decreasing relative humidity, and the brown rot infections increase with temperature. Simulations also highlighted the influence of interactions between pre- and post-harvest conditions on the brown rot prevalence and the fruit yield at the end of storage. We finally used the modeling framework to search for the combinations of pre- and post-harvest conditions thatoptimize a performance score encompassing fruit quality and yield. The relative importance assigned to the fruit quality criteria largely affected the choice of the optimal scenarios. The results also pointed out a trade-off between quality criteria, and in particular sweetness, and the fruit yield. The use of this modeling framework could support the dialogue between the actors of the fruit value chain, by suggesting scenarios of pre-harvest practices and storage conditions that satisfy their expectations, without prejudging the subsequent behavior of the fruit after storage
Etude des interactions climat radiatif x génotypes sur la concentration en flavonoïdes des fruits chez des agrumes diploïdes et tétraploïdes by Marie Durand-Hulak( )

1 edition published in 2015 in French and held by 1 WorldCat member library worldwide

Phenolic compounds have important antioxidant properties and are generally associated with the protective effect of diets rich in fruits and vegetables. They also contribute to their organoleptic quality and participate to plant response to biotic and abiotic stresses. Citrus fruits are one of the most important fruit crops in the world. Thus, they represent an important nutritional source of phenolic compounds. In the current context of citrus crop, improving the organoleptic and nutritional qualities of fruit as well as the improvement of plant resistance to biotic and abiotic contraints are priorities for breeders. Phenolic compounds are therefore an important target for citrus selection. However, the regulation of the phenolic compounds accumulation in citrus as well as their physiological roles remain unclear. Moreover, citrus breeding involves selection of tetraploid cultivars. In case of tetraploidy, we have to distinguished, doubled diploids from somatic hybrid coming from genome addition. However, the effect of ploidy on the composition of phenolic compounds remains not well understood. To address these issues, we first developed a high-throughput method for the analysis of phenolic compounds by ultra high performance liquid chromatography (UPLC) coupled with mass spectrometry (MS). This method was validated on 4 tissues and allowed the analysis of 64 metabolites belonging to 6 different chemical classes simultaneously, in 20 minutes. This method allowed us to map the phenolic compound profiles of 11 Citrus species, to improve phylogenetic classifications based on those compounds and to identify the steps of the biosynthetic pathway involved in the phenotypic variability. We then applied this method to study the variability of flavonoid profiles in Citrus diploids, doubleds diploid and coming from somatic hybridization. This study highlighted that some genotypes, including oranges (C. sinensis (L.) Osbeck) did not accumulate flavonoid-neohesperidosides with bitter flavors, while grapefruits (C. paradisi Macf.) accumulated those molecules in large quantities. In addition, we have shown that genome doubling did not cause significant changes in the accumulation of glycosylated flavonoids while genome addition can induce transgressive over-accumulation of these compounds. The analysis of two genes encoding rhamnosyl transferases and involved in rutinoside and neohesperidosides formation, failed to validate this level of regulation but suggested other mechanisms regulating the accumulation of glycosylated flavonoids in the allotetraploid. Finally, we studied the response of two Citrus genotypes subjected to abiotic stress, UV-B, and the dependence of this response on ploidy level. We analyzed flavonoid profiles in growing and mature leaves during UV-B treatment, applied in greenhouses, and after the end of the treatment. Our study revealed that unlike diploids, polyploids were weakly affected by UV-B. The high levels of flavonoids screening UV-B combined with high concentrations of quercetin and luteolin derivatives, with antioxidant activity, may buffer the negative effect of UV-B radiation in polyploids. The induction of DFR and F3H genes and the rise in anthocyanins and quercetin derivatives under the action of UV-B may help to prevent other biotic and abiotic stresses
 
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