1,721,117 research outputs found
Quantifier pour optimiser les performances et services rendus de différentes espèces de légumineuses en exploitations agricoles
No full textAnalysis of genotype-environment -crop management interactions of durum wheat-grain legume intercrops for optimizing cultivar choice and cropping system design
No full textAccroître la biodiversité dans les agroécosystèmes est une stratégie écologique qui permettrait de rendre les productions plus durables. Une des pistes prometteuses est la culture en association de deux espèces sur une même parcelle et pendant une durée significative de leur cycle de développement. Ces cultures associées et notamment les mélanges céréalelégumineuse présentent de nombreux avantages, en particulier dans les systèmes à faible disponibilité en azote, en termes de production, de qualité et de bénéfices environnementaux. Ces performances sont étroitement liées à l’expression des complémentarités de niche et la réduction des effets de compétition entre les composantes de l’association. Les interactions interspécifiques dépendent fortement des caractéristiques phénotypiques (physiologie, morphologie, phénologie) des espèces et variétés associées. L’objectif de notre travail était d’étudier l’effet de la variabilité génotypique de espèces sur les performances des cultures associées de blé dur-légumineuse à graine et d’analyser le comportement des cultivars vis-à-vis des interactions inter et intra-spécifiques. Pour cela, nous avons mis en place deux expérimentations de 2011 à 2013 afin de tester plusieurs combinaisons de variétés présentant des traits phénotypiques différents. Chaque variété a été semée en culture pure en densité normale et en demi-densité (afin d’étudier les interactions intra-spécifiques) et en association de type substitutive (les deux espèces sont semées en demi densité et en mélange sur le rang) afin d’étudier les interactions interspécifiques. Nos résultats ont confirmé que le comportement d’un génotype est variable entre culture pure et association et que la performance d’une espèce en association dépendrait de sa performance en culture pure mais aussi de sa compétitivité. Ce pouvoir compétitif est sensible aux traits phénotypiques de chaque espèce et à la variation des conditions pédoclimatiques. Une analyse de la dynamique des interactions interspécifiques montre qu’à partir de la période de floraison des légumineuses, les compétitions deviendraient plus intenses et pourraient influencer les rendements en grains. In fine, ce travail nous a permis d’identifier des traits marqueurs de la performance des légumineuses en association qui serviront à concevoir des idéotypes adaptés aux couverts plurispécifiques afin d’optimiser les services rendus par ces systèmes cultivés.Increasing biodiversity in agroecosystems may contribute to a sustainable productions. Intercropping, the growth of two or more species in the same space at the same time, is considered as a practical application of ecological principles based on biodiversity. Grain legume-cereal intercropping reveals many potential advantages in productivity, stability of outputs and ecological sustainability particularly in low N-input systems. These advantages occur when intercrop components have a complementary ecological niches and competitive interaction are reduced. Interspecific interactions are greatly influenced by phenotypic traits (physiological, morphological and phenological) among cultivars and species. The aim of our study is to study the effect of genotypic variability of species on the performance of durum wheat-grain legume intercrops and to analyze the response of cultivars toward inter and intraspecific interactions. An experimental trial was carried out during two years (2011 to 2013) to test different cultivar combinations. Each cultivar and specie was cultivated as sole crop, half density sole crop and intercrop in a replacement design to evaluate inter- and intra-specific interactions. Our results confirmed that genotype behavior is different between sole crop and intercropping. The intercrop performance is dependent on its performance on sole crop and on its competitiveness. Phenotypic traits and pedoclimatic conditions influence the competitive ability of intercrops. Besides, a dynamic analysis of interspecific interactions shows that from the legumes flowering period, competitions would be the most intense and would impact the grain yield. Finally, this study has allowed to identify some indicators of the performance of grain legumes on intercropping that would help to concept ideotypes adapted to multispecies systems in order to optimize their advantages
Culture associée: Définition
No full textNational audienceIntercropping is an agricultural practice whereby at least two species are cropped together during a significant period of their growth.Intercropping aims at using more efficiently the available resources by promoting complementarity between species in order to increase the products’ production on a given surface of land and quality (e.g. level of proteins of a cereal), but also to limit diseases, pests and weeds pressure...La culture associée est une pratique agricole qui consiste à implanter dans une parcelle au moins deux espèces pendant une période significative de leur croissance. Elle vise à utiliser plus efficacement les ressources disponibles en valorisant la complémentarité entre les espèces pour augmenter la production et la qualité des produits mais aussi lutter contre les maladies, ravageurs et adventices..
Purification of Nongreen Plastids (Proplastids and Amyloplasts) from Angiosperms, and Isolation of Their Envelope Membranes
No full textInternational audiencePlastids, a wide family of plant specific organelles, exist in all plant cells in a number of different forms with different functions essential for plant life. Among them, chloroplasts are by far the more extensively studied owing to their central role in photosynthesis. However, other plastid family members, often referred to as nongreen plastids, play also major roles in the physiology of higher plants and could be better suited for studies of specific metabolic processes in heterotrophic plant cells. Unfortunately, serious technical problems are frequently encountered with separating intact, active nongreen plastids from contaminating membranes and mitochondria. Here, we provide detailed protocols suitable for the large scale preparation of intact and highly pure proplastids from cauliflower buds, as well as amyloplasts from sycamore cultured cells, and for the subsequent separation of their surrounding envelope membranes from the stroma and other plastid fractions. Both methods proved to be highly reliable and have been instrumental for in-depth investigations on biochemistry and physiology of nongreen plastids
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Purification of Nongreen Plastids (Proplastids and Amyloplasts) from Angiosperms, and Isolation of Their Envelope Membranes
No full textInternational audiencePlastids, a wide family of plant specific organelles, exist in all plant cells in a number of different forms with different functions essential for plant life. Among them, chloroplasts are by far the more extensively studied owing to their central role in photosynthesis. However, other plastid family members, often referred to as nongreen plastids, play also major roles in the physiology of higher plants and could be better suited for studies of specific metabolic processes in heterotrophic plant cells. Unfortunately, serious technical problems are frequently encountered with separating intact, active nongreen plastids from contaminating membranes and mitochondria. Here, we provide detailed protocols suitable for the large scale preparation of intact and highly pure proplastids from cauliflower buds, as well as amyloplasts from sycamore cultured cells, and for the subsequent separation of their surrounding envelope membranes from the stroma and other plastid fractions. Both methods proved to be highly reliable and have been instrumental for in-depth investigations on biochemistry and physiology of nongreen plastids
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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