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351.
Amira Mougou-Hamdane Xavier Giresse Cyril Dutech Marie-Laure Desprez-Loustau 《Annals of Forest Science》2010,67(2):212-212
352.
Euvaldo F. CabralPaula Cristina Pecora Aldo Ivan Céspedes ArceAdriano R. Bruno Tech Ernane Jose Xavier Costa 《Computers and Electronics in Agriculture》2011,76(1):1-5
This paper demonstrates the oscillatory characteristics of electrical signals acquired from two ornamental plant types (Epipremnum pinnatum and Philodendron scandens - Family Araceae), using a noninvasive acquisition system. The electrical signal was recorded using Ag/AgCl superficial electrodes inside a Faraday cage. The presence of the oscillatory electric generator was shown using a classical power spectral density. The Lempel and Ziv complexity measurement showed that the plant signal was not noise despite its nonlinear behavior. The oscillatory characteristics of the signal were explained using a simulated electrical model that establishes that for a frequency range from 5 to 15 Hz, the oscillatory characteristic is higher than for other frequency ranges. All results show that non-invasive electrical plant signals can be acquired with improvement of signal-to-noise ratio using a Faraday cage, and a simple electrical model is able to explain the electrical signal being generated. 相似文献
353.
Silvana Creste Klaus A. G. Accoroni Luciana R. Pinto Roland Vencovsky Marcos A. Gimenes Mauro A. Xavier Marcos G. A. Landell 《Euphytica》2010,172(3):435-446
Target region amplification polymorphism (TRAP) markers were used to estimate the genetic similarity (GS) among 53 sugarcane
varieties and five species of the Saccharum complex. Seven fixed primers designed from candidate genes involved in sucrose metabolism and three from those involved in
drought response metabolism were used in combination with three arbitrary primers. The clustering of the genotypes for sucrose
metabolism and drought response were similar, but the GS based on Jaccard’s coefficient changed. The GS based on polymorphism
in sucrose genes estimated in a set of 46 Brazilian varieties, all of which belong to the three Brazilian breeding programs,
ranged from 0.52 to 0.9, and that based on drought data ranged from 0.44 to 0.95. The results suggest that genetic variability
in the evaluated genes was lower in the sucrose metabolism genes than in the drought response metabolism ones. 相似文献
354.
Linde Besard Veerle Mommaerts Jessica Vandeven Xavier Cuvelier Guido Sterk Guy Smagghe 《Pest management science》2010,66(7):786-793
BACKGROUND: This project assessed the potential hazards of different classical and novel acaricides against an important non‐target and beneficial insect for the pollination of wild flowers and cultivated crops, the bumblebee Bombus terrestris (L). Twenty‐three acaricides used commercially in the control of phytophagous mites (Acari) were tested in greenhouses and/or the open field. Side effects included acute mortality and also sublethal effects on nest reproduction. The different compounds were administered in the laboratory via three different worst‐case field scenario routes of exposure: dermal contact and orally via the drinking of treated sugar water and via treated pollen. The compounds were tested at their respective maximum field recommended concentration (MFRC), and, when strong lethal effects were observed, a dose–response assay with a dilution series of the MFRC was undertaken to calculate LC50 values. RESULTS: From the different acaricide classes, several chemistries caused high levels of acute toxicity in bumblebee workers, especially bifenthrin and abamectin which resulted in 100% mortality by contact. In addition, several acaricides tested were found to have a detrimental effect on drone production. For oral exposures via treated sugar water, the dose–response assay showed the LC50 values for abamectin, bifenazate, bifenthrin and etoxazole to be 1/15 MFRC (1.17 mg AI L?1), 1/10 MFRC (9.6 mg AI L?1), 1/83 MFRC (0.36 mg AI L?1) and 1/13 MFRC (4.4 mg AI L?1) respectively, indicating that their use should be carefully evaluated. CONCLUSION: Overall, the results suggest that most of the acaricides tested are compatible with bumblebees, with the exceptions of abamectin, bifenazate, bifenthrin and etoxazole. However, the risks also depended on the type of treatment. As a result, the sugar water treatment seems to present the worst‐case situation of exposure, indicating that this approach is suitable for determining the hazards of pesticides against bumblebees. Finally, it is suggested that future tier testing under more field‐related conditions is required for a final decision of their risks. Copyright © 2010 Society of Chemical Industry 相似文献
355.
Xavier Domene Stefania Mattana Wilson Ramírez Joan Colón Patrícia Jiménez Teresa Balanyà Josep M. Alcañiz Manel Bonmatí 《Journal of Soils and Sediments》2010,10(1):30-44
Background, aim, and scope
Mining activities disturb land and reduce its capacity to support a complete functional ecosystem. Reclamation activities in this case are not easy due to the large amount of soil required. This is why mining debris are usually used as surrogate of soil, despite their unsuitable physicochemical properties. However, these properties can be improved with the amendment using an organic source, usually sewage sludge. Nevertheless, the use of sludge might lead to impacts on soil and water ecosystems because of its physicochemical properties and pollutant content. The aim of this study is to assess the suitability of the use of mining debris amended with sewage sludge as practice for the reclamation of land degraded by limestone-quarrying activities. 相似文献356.
357.
Ayman F. Omar Xavier Foissac 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(2):353-360
Symptoms reminiscent of phytoplasma infection were observed in four provinces (governorates) of Egypt in fields of eggplants,
tomato plants and squash. Diseased plants exhibited stunting, leaf yellows and flower development abnormalities. PCR amplification
of 16SrDNA with phytoplasma-specific primer pairs confirmed the phytoplasma presence. Sequencing and phylogenetic analysis
indicated that all phytoplasmas had the same partial 16SrDNA sequence, assigning them to the 16SrII-D phytoplasma subgroup.
Disease incidence was about 1% among the 20 squash fields surveyed and equally varied from 4% to 15% in the 20 eggplant fields
and in the 40 tomato fields inspected. The widespread distribution of this phytoplasma in annual solanaceous and cucurbit
crops suggests a wider plant host range including wild plants that could act as reservoir and insist on the need for a insect
vector survey. A finer genetic differentiation of Egyptian 16SrII-D phytoplasma strains from different geographical origins
and different host plants should help to better trace such epidemics. 相似文献
358.
Donati JF Forveille T Cameron AC Barnes JR Delfosse X Jardine MM Valenti JA 《Science (New York, N.Y.)》2006,311(5761):633-635
Understanding how cool stars produce magnetic fields within their interiors is crucial for predicting the impact of such fields, such as the activity cycle of the Sun. In this respect, studying fully convective stars enables us to investigate the role of convective zones in magnetic field generation. We produced a magnetic map of a rapidly rotating, very-low-mass, fully convective dwarf through tomographic imaging from time series of spectropolarimetric data. Our results, which demonstrate that fully convective stars are able to trigger axisymmetric large-scale poloidal fields without differential rotation, challenge existing theoretical models of field generation in cool stars. 相似文献
359.
360.
Xavier?PonsEmail author Belén?Lumbierres Ribes?Antoni Petr?Stary 《Journal of pest science》2011,84(4):437-445
Alfalfa aphids were monitored and aphid parasitism was determined in three crop-growing seasons (2007–2009) in commercial
alfalfa fields in valleys close to the Pyrenees, where an intensive arable crop rotation is practised under non-tillage and
an integrated pest management system. Acyrthosiphon pisum, Therioaphis trifolii, and Aphis craccivora were the aphid species colonizing alfalfa fields but their occurrence varied between years. Thirteen Aphidiinae parasitoid
species and four Aphelinidae from the genus Aphelinus sp. were recorded. Aphidius ervi was the prevalent parasitoid species associated with A. pisum but Praon barbatum was also noticeable, especially during the first year. Trioxys complanatus and P. exsoletum were the only species associated with T. trifolii. Lysiphlebus fabarum was the prevalent parasitoid species associated with A. craccivora. The occurrence of Lysiphlebus testaceipes parasitizing A. craccivora on alfalfa is a new record for the study region because this parasitoid species had only been previously found on weeds.
Only A. pisum and A. craccivora were parasitized by Aphelinus sp. Whereas A. abdominalis and A. semiflavus were associated with A. pisum, A. chaonia, and Aphelinus sp. nr. albipodus were associated with A. craccivora. Associations between aphid species and Aphidiinae or Aphelinidae parasitoid species emphasize that individual aphid species
also possess individual parasitoid complexes (guilds) which do not interfere with each other in alfalfa. Alloxysta victrix, A. macrophadna, Alloxysta spp., Asaphes suspensus, A. vulgaris, Dendrocerus aphidum, Pachyneuron aphidis and Syrphophagus aphidivorus were the hyperparasitoids associated with aphid–parasitoid complexes. Our study showed A. ervi, T. complanatus, P. exsoletum, and L. fabarum as potential candidate species which could provide biological control of their respectively aphid hosts in alfalfa. 相似文献