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Differential effect of resistance inducers on the susceptibility of lettuce varieties to Sclerotinia sclerotiorum and Botrytis cinerea
No full textThe preventive use of resistance inducers has been shown to be an interesting method to reduce dependency on pesticides for plant protection. However, little is known on possible differences in the protective effects of such methods for different varieties of a given crop. In the present study, we assessed the effect of three compounds (acibenzolar-S-méthyl, a calcium-based mineral compound and a yeast extract) for the protection of six varieties of lettuce against two major pathogens, Sclerotinia sclerotiorum and Botrytis cinerea. The compounds were sprayed on the plants three days before inoculation. A water spray was used as a control. The protective effect of the compounds was then assessed by comparing the size of lesions developing on inoculated leaves.
For both pathogens, none of the compounds fully inhibited disease development. However, reduction in lesion size was observed on some of the leaves. The effect of the three compounds was different for the two pathogens. For tests with B. cinerea, effects of plant treatment were not statistically significant. In contrast, significant effects were found for five of the varieties inoculated with S. sclerotiorum. Overall, the yeast extract provided the highest level of protection against that pathogen. However, for all compounds, the extent of the protective effect depended on the variety. Furthermore, in some cases the effect of the compound was opposite to that desired and disease was more severe on treated plants than on the water control. Possible consequences for field application of such methods will be discussed
Biological control of Sclerotinia sclerotiorum on lettuce: does the efficacy of protection depend on the cultivar and the strain of the pathogen?
No full text2 annexesMasterBiocontrol based on micro-organisms and resistance inducers is considered as an interesting method to reduce dependency on pesticides for plant protection. The efficacy of these control methods is known to be influenced by complex factors, still only partially understood, which complicate their use in the field. This study was focused on two main issues, (1) Variability in the susceptibility of Sclerotinia sclerotiorum to the hyperparasitic fungus Coniothyrium minitans. Results obtained with seven strains of S. sclerotiorum provide a possible hypothesis to explain the variability of field efficacy of Contans® observed in France on various crops. It also provided methodological background to further explore this hypothesis. Further work will foremost require the elucidation of the source of contamination with Penicillium sp. encountered during the study. (2) Resistance inducers to protect different cultivars of lettuce against S. sclerotiorum. Three compounds (acibenzolar-S-methyl, a calcium-based mineral compound and a yeast extract) were evaluated for the protection of six lettuce cultivars. Overall, the yeast extract provided the highest level of protection against that pathogen. However, for all compounds, the extent of the protective effect depended on the cultivar.La mise en œuvre de biocontrôle à l'aide de micro-organismes et d'inducteurs de résistance est considérée comme une méthode intéressante pour réduire la dépendance aux pesticides pour la protection des végétaux. L'efficacité de ces méthodes au champ est influencée par des facteurs complexes, encore partiellement compris, qui compliquent souvent leur utilisation. Cette étude était focalisée sur deux principales questions: (1) La variabilité de la sensibilité de Sclerotinia sclerotiorum au champignon hyperparasite Coniothyrium minitans. Les résultats obtenus avec sept souches de S. sclerotiorum fournissent une hypothèse pour expliquer la variabilité de l'efficacité au champ de Contans® observée en France sur diverses cultures. Ils donnent également un contexte méthodologique pour explorer davantage cette hypothèse. D'autres travaux seront également nécessaires pour élucider la source de contamination par Penicillium sp. observée lors de l'étude (2) Les inducteurs de résistance pour protéger différents cultivars de laitue contre S. sclerotiorum. Trois composés (acibenzolar-S-méthyle, un composé minéral à base de calcium et d'un extrait de levure) ont été évalués pour la protection de six variétés de laitues. Dans l'ensemble, l'extrait de levure a montré le plus haut niveau de protection. Cependant, pour tous les composés, la mesure de l'effet de protection dépend du cultivar
Pengendalian Hayati Sclerotinia sclerotiorum pada Tanaman Selada: Apakah Keefektifan Pengendalian Dipengaruhi oleh Kultivar dan Strain Patogen?
No full textPengendalian hayati dengan mikroorganisme dan penginduksi ketahanan merupakan metode untuk mengurangi ketergantungan terhadap penggunaan pestisida kimia sintetik dalam pengendalian penyakit tanaman. Keefektifan pengendalian ini dipengaruhi oleh faktor-faktor kompleks yang belum dapat dipahami secara keseluruhan. Penelitian ini mengkaji 2 topik utama, (1) Kerentanan dari 7 isolat patogen Sclerotinia sclerotiorum terhadap cendawan hiperparasit Coniothyrium minitans. Setiap sclerotia dari masing-masing strain patogen diinokulasi dengan 105 spora C. minitans per ml air steril dan diinkubasi dalam kondisi lembab. Pengamatan perkembangan C. minitas dilakukan pada 3 dan 4 minggu setelah inokulasi menggunakan mikroskop binokular dan mikroskop elektron. Tiga isolat S. sclerotiorum kemudian dipilih untuk pengujian dual kultur; (2) Penginduksi ketahanan untuk melindungi berbagai kultivar selada terhadap serangan S. sclerotiorum. Enam kultivar selada masing-masing diberi perlakuan dengan 3 jenis suspensi penginduksi ketahanan (acibenzolar-S-methyl 0.01%, bahan mineral kalsium 0.1% dan ekstrak khamir 0.2%). Tiga hari setelah perlakuan, setiap kultivar diinokulasi dengan miselium patogen S. Sclerotiorum dengan metode detached leaf. Pengamatan dilakukan 2 hari setelah inokulasi dengan mengukur luasan gejala nekrotik yang terbentuk pada daun. Hasil studi pertama menunjukkan bahwa 2 dari 7 isolat S. sclerotiorum, isolat SS4 dan SS6, lebih banyak diinfeksi oleh cendawan antagonis C. minitans. Akan tetapi, berdasarkan persentase mortalitas dapat diketahui bahwa isolat SS4 (±60%) merupakan isolat yang paling rentan terhadap C. minitans dibandingkan dengan isolat SS6 (±10%). Hal ini menjelaskan mengenai keragaman efikasi dari penggunaan agen antagonis di lapangan yang diamati pada beberapa pertanaman di Prancis. Selanjutnya, hasil studi kedua menunjukkan bahwa efek perlindungan dari semua jenis penginduksi ketahanan berbeda terhadap setiap kultivar. Walaupun secara statistik tidak terdapat pengaruh yang nyata pada interaksi antara kultivar tanaman dan bahan penginduksi uji, dari studi kedua ini dapat diketahui bahwa ekstrak khamir memiliki kemampuan untuk menginduksi ketahanan pada sebagian besar kultivar uji dengan persentase perlindungan mencapai 70%. Penyakit Lettuce drop yang disebabkan oleh S. sclerotiorum dapat dikendalikan dengan menggunakan cendawan antagonis C. minitans dan penginduksi ketahanan sebagai strategi pengendalian alternatif. Metode-metode ini memiliki prospek yang baik, tetapi dibutuhkan pengkajian lebih lanjut untuk mengoptimalkan keefektifannya di lapangan. Kata kunci
Biological control of Sclerotinia sclerotiorum on lettuce: does the efficacy of protection depend on the cultivar and the strain of the pathogen?
No full text2 annexesMasterBiocontrol based on micro-organisms and resistance inducers is considered as an interesting method to reduce dependency on pesticides for plant protection. The efficacy of these control methods is known to be influenced by complex factors, still only partially understood, which complicate their use in the field. This study was focused on two main issues, (1) Variability in the susceptibility of Sclerotinia sclerotiorum to the hyperparasitic fungus Coniothyrium minitans. Results obtained with seven strains of S. sclerotiorum provide a possible hypothesis to explain the variability of field efficacy of Contans® observed in France on various crops. It also provided methodological background to further explore this hypothesis. Further work will foremost require the elucidation of the source of contamination with Penicillium sp. encountered during the study. (2) Resistance inducers to protect different cultivars of lettuce against S. sclerotiorum. Three compounds (acibenzolar-S-methyl, a calcium-based mineral compound and a yeast extract) were evaluated for the protection of six lettuce cultivars. Overall, the yeast extract provided the highest level of protection against that pathogen. However, for all compounds, the extent of the protective effect depended on the cultivar.La mise en œuvre de biocontrôle à l'aide de micro-organismes et d'inducteurs de résistance est considérée comme une méthode intéressante pour réduire la dépendance aux pesticides pour la protection des végétaux. L'efficacité de ces méthodes au champ est influencée par des facteurs complexes, encore partiellement compris, qui compliquent souvent leur utilisation. Cette étude était focalisée sur deux principales questions: (1) La variabilité de la sensibilité de Sclerotinia sclerotiorum au champignon hyperparasite Coniothyrium minitans. Les résultats obtenus avec sept souches de S. sclerotiorum fournissent une hypothèse pour expliquer la variabilité de l'efficacité au champ de Contans® observée en France sur diverses cultures. Ils donnent également un contexte méthodologique pour explorer davantage cette hypothèse. D'autres travaux seront également nécessaires pour élucider la source de contamination par Penicillium sp. observée lors de l'étude (2) Les inducteurs de résistance pour protéger différents cultivars de laitue contre S. sclerotiorum. Trois composés (acibenzolar-S-méthyle, un composé minéral à base de calcium et d'un extrait de levure) ont été évalués pour la protection de six variétés de laitues. Dans l'ensemble, l'extrait de levure a montré le plus haut niveau de protection. Cependant, pour tous les composés, la mesure de l'effet de protection dépend du cultivar
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
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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