131,021 research outputs found
Can Physiology Help Us to Combat Late Blight in Potato?
No full textLate blight is a devastating disease in potato production world-wide. Breeding for resistance is complex because of the versatile and aggressive population of Phytophthora infestans, which overcomes any new genetic source of resistance very rapidly. There are reliable fungicides available to control the disease, but chemical control is costly and harmful to the environment. There are no cultural practices reducing the infestation, which are reliable enough to cope with the disease in a non-chemical way. Given the close link between the physiological condition of the crop and its resistance to late blight, this paper addresses the question whether crop physiology can help to combat the disease. Although there are possibilities to (partly) escape to the late blight by advancing the crop cycle or the tuber bulking, it is concluded that crop physiology can do little to reliably reduce the susceptibility to late blight. Breeding for resistance remains the best option
Opportunities and constraints of tomato production in Eritrea
No full textTomato is an important vegetable in Eritrea, grown across the entire country. Yields in Eritrea are comparatively low, due to agronomic, institutional and market constraints. We carried out a survey throughout the country based on a participatory rural appraisal, discussion groups and interviews with staff members of the Ministry of Agriculture. Results showed that farmers preferred varieties with a prolonged harvesting period and a long storage life unless other varieties are better yielding and can immediately be marketed. However, their knowledge on varieties is limited while maintaining their own seeds. Seedlings are established in nurseries and subsequently transplanted once they have reached a height of 10 to 15 cm. Spacing, staking, pruning and irrigation are important aspects of proper crop management. Flower abortion is common in some areas and the crop is affected by several diseases and pests. The harvesting takes place over a prolonged period and timing of harvest of individual fruits is based on skin colour. There are significant price differences based on size grade. Seasonality of the crop causes problems with marketing and price fluctuation. It is recommended to improve the farmer’s knowledge on variety characteristics, to improve the seed systems and train the farmers in improved crop managemen
Diversity between and within farmers’ varieties of tomato from Eritrea
No full textTomato yields in Eritrea are low (15 Mg/ha) compared with 19 Mg/ha in Africa and 27 Mg/ha worldwide. This is partly caused by poor quality of varieties used. This study analysed the diversity among and heterogeneity within farmers’ varieties of tomato from Eritrea and compared these varieties with other African and Italian varieties. Fifteen simple sequence repeat (SSR) markers were used for the genetic analysis. Genetic similarities among the varieties were calculated and an Unweighted Pair Group Method with Arithmetic Mean analysis was performed. Furthermore, individual plants of varieties were genotyped to evaluate uniformity within varieties. A high degree of diversity was observed among the Eritrean varieties. Thirteen out of the 15 SSRs were polymorphic, with 2 to 5 alleles per marker. The dendrogram showed two major types of varieties: San-Marzano and Marglob. Eritrean varieties were closely related to old Italian varieties in both types. Analysis of the within-variety variation showed that the Eritrean tomato genotypes were less uniform than the other varieties, probably because of deliberate mixing. A survey among farmers showed that some of them purposely mixed seeds to prolong the harvesting period, for yield stability and stress tolerance. Farmers value ‘new material’ as a source of influ
De hervorming van de landbouw moet ingrijpender. Een vergelijking vam twee visies.
No full textHet belang van nieuw beleid zoals dat is gedefinieerd in de werkgroepen De Zeeuw c.s. en Struik c.s. Beide groepen geven aan hoe de landbouw, natuur en milieu beter kunnen samengaa
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Wheat 2004 outdoor
No full textThis dataset contains the underlying data for the study:
Evers JB, Vos J, Andrieu B, Struik PC. 2006. Cessation of tillering in spring wheat in relation to light interception and red : far-red ratio. Annals of Botany, 97: 649-658,
http://dx.doi.org/10.1093/aob/mcl020
Evers JB, Vos J, Fournier C, Andrieu B, Chelle M, Struik PC. 2007. An architectural model of spring wheat: evaluation of the effects of population density and shading on model parameterization and performance. Ecological Modelling 200: 308-320
http://dx.doi.org/10.1016/j.ecolmodel.2006.07.042
Chelle M, Evers JB, Combes D, Varlet-Grancher C, Vos J, Andrieu B. 2007. Simulation of the three-dimensional distribution of the red:far-red ratio within crop canopies. New Phytologist, 176: 223-234
http://dx.doi.org/10.1111/j.1469-8137.2007.02161.x
Evers JB, Vos J, Chelle M, Andrieu B, Fournier C, Struik PC. 2007. Simulating the effects of localized red:far-red ratio on tillering in spring wheat (Triticum aestivum) using a three-dimensional virtual plant model. New Phytologist, 176: 325-336
http://dx.doi.org/10.1111/j.1469-8137.2007.02168.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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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