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Changes in sunflower breeding over the last fifty years
No full textThis article discusses changes in sunflower breeding objectives since the introduction of hybrid varieties 50 years ago. After a reminder of the importance of some early programmes, Canadian in particular, the present situation for each breeding objective is compared with those encountered earlier. Breeding for yield has changed from maximum possible yield under intensive agriculture to yield with resistance to abiotic stresses, moderate droughts and shallow soils in particular, helped by collaboration with agronomists to produce crop models. Breeding for oil has changed from quantity to quality and the value of seed meal is again becoming economically important. Necessary disease resistances vary with agronomic practises and selection pressure on pathogens according to varietal genetics. The possibilities of new types of sunflower are also discussed. Advances in genomics will change breeding procedures, but with rapidly changing molecular techniques, international collaboration is particularly important
The effect of male sterility on oil content and seed yield in sunflowers (Helianthus annuus L.)
No full textInternational audienc
The effect of male sterility on oil content and seed yield in sunflowers (Helianthus annuus L.)
No full textMeasurements of oil content and seed yield of some experimental sunflower hybrids between a tester line and individuals from a population showed that the male sterile hybrids contained a mean of 2.62 % more oil than male fertile hybrids and had a higher seed yield (103.19 % of the control varieties compared with 94.97 %). Similar differences were found between inbred male sterile plants and their isogenic maintainers under self pollination (1.25 % more oil, 4.11 g/plant more seed) ans cross pollination (1.13 % more oil, 7.56 g/plant more seed). The greater oil content and seed yield of male sterile plants did not appear to be related to the cytoplasm determining male sterility nor to cross pollination it could be due to the male sterility as such.Des études de la teneur en huile et du rendement en grains d’hybrides expérimentaux, fabriqués à partir d’individus d’une population de tournesol, ont montré des différences entre les hybrides mâle-stériles et mâle-fertiles. Les premiers avaient une teneur en huile supérieure de 2,62 p. 100 et un rendement supérieur de 8,22 p. 100 (par rapport à des variétés témoins). Des différences ont aussi été trouvées entre des lignées mâle-stériles cytoplasmiques et leurs mainteneurs de stérilité isogéniques. En autofécondation, les mâle-stériles avaient 1,25 p. 100 d’huile en plus de 4,11 g/plante de semences en plus et, en fécondation libre, 1,13 p. 100 d’huile en plus et 7,56 g/plante de semences en plus. Il semble que les différences entre mâle-stérile et mâle-fertile ne soient pas dues au cytoplasme mâle-stérile de Helianthus petiolaris, ni à la fécondation libre par rapport à l’autofécondation. Aussi, est-il proposé qu’elles soient liées à l’absence de production de pollen
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Etude des relations entre la precocite du tournesol et son rendement, sa teneur en huile, son developpement et sa morphologie
No full textDans une étude sur 25 hybrides de tournesol, issus d’un plan factoriel de croisement, ainsi que des variétés cultivées, 2 matrices de corrélations linéaires totales entre différents paramètres ont été réalisées afin d’étudier les liaisons entre différents caractères du développement et l’humidité à la récolte, le rendement en grains et la teneur en huile. La précocité à la récolte est corrélée avec la durée totale levée-maturité physiologique (r = 0,74 **), et plutôt avec la durée floraison-maturité physiologique (0,69 **) que la durée levée-floraison (0,54 *). Les caractères morphologiques ne sont pas révélateurs de la précocité. Le rendement est corrélé avec des caractères morphologiques de vigueur, mais parmi ses composantes le nombre de grains par capitule paraît plus important que le poids de 1 000 grains. La teneur en huile est peu corrélée avec d’autres caractères. En l’absence de corrélation rendement-précocité la sélection de tournesols précoces à haut rendement devrait être possible mais nécessiterait des observations en fin de cycle de la maturité des graines.The developmental and agronomic characteristics of sunflowers were observed in trials involving 25 hybrids from a factorial cross and 3 commercial varieties, over 2 years, 1986 and 1987. There were significant differences between genotypes for all characteristics except the duration sowing-emergence (table I). From the results, 2 matrices of total linear correlations were calculated between different parameters in order to study relations between developmental stages and earliness at harvest, yield and oil content (tables II and III). The length of developmental phases before and after flowering are independent. The duration emergencephysiological maturity was correlated with the periods before and after flowering, but more closely with the duration flowering-maturity (r = 0.87 **). Earliness at harvest appears correlated with the total duration emergencephysiological maturity (r = 0.74 **), and follows the same pattern, being more especially related to the duration flowering-physiological maturity (r = 0.69 **) than to the duration emergence-flowering (r = 0.54 *). Of the morphological characters observed, most do not provide any useful indication concerning earliness; only leaf number shows a significant correlation with emergence-flowering and emergence-maturity. In contrast, yield is significantly correlated with morphological characters which vary with plant vigour, such as head and basal stem diameter and plant height. For the components directly determining yield, seed number per capitulum appears more important than 1 000 seed weight. In the conditions of the trials, yield appears most related to characters determined before flowering. Oil content is not closely linked with other characters, except lateness to some extent. It is concluded that since earliness at harvest depends on the sum of all the vegetative stages, more particularly those after flowering, no juvenile character provides a satisfactory forecast. Earliness can only be determined by end of cycle observations on seed maturation. However, the absence of any significant correlation between yield and earliness suggests that it should be possible to select for high yielding early sunflowers
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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