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排序方式: 共有249条查询结果,搜索用时 15 毫秒
201.
Martin Weis Christoph Gutjahr Victor Rueda Ayala Roland Gerhards Carina Ritter Florian Schölderle 《Gesunde Pflanzen》2008,60(4):171-181
Site-specific weed control techniques have gained interest in the precision farming community over the last years. Managing weeds on a subfield level requires measuring the varying density of weeds within a field. Decision models aid in the selection and adjustment of the treatments, depending on the weed infestation. The weed control can be done either with herbicides or mechanically. A site-specific herbicide application technology can save large amounts of herbicides. Mechanical weed control techniques adapting to the weed situation in the field are applicable to a wide spectrum of crops. Site-specific techniques for the detection and management of weeds are presented. A system for the discrimination of different weed species and crops from images is described, which generates weed maps automatically. Models for the yield effect of weeds are developed and applied in on-farm-research experimental setups. Economic weed thresholds are derived and used for a herbicide application with a patch sprayer. 相似文献
202.
Tamantini Swati Bergamasco Sara Portoghesi Luigi Vettraino Anna Maria Zikeli Florian Mugnozza Giuseppe Scarascia Romagnoli Manuela 《European Journal of Forest Research》2022,141(4):683-698
European Journal of Forest Research - Sweet chestnut forests occupy an important role in Italy and Europe, its resilience is often affected by aggressive pathogen attack. In the last times some... 相似文献
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204.
AISHAN Tayierjiang HALIK Ü mü t Florian BETZ TIYIP Tashpolat DING Jianli NUERMAIMAITI Yiliyasijiang 《干旱区科学》2015,7(4):544-554
Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a dominant tree species along the Tarim River watershed, plays an irreplaceable role in the sustainable development of regional ecology, economy and society. However, as the result of climate changes and human activities, the natural riparian ecosystems within the whole river basin were degraded enormously, particularly in the lower reaches of the river where about 320 km of the riparian forests were either highly degraded or dead. In this study, we presented one of the main criteria for the assessment of vitality of P. euphratica forests by estimating the defoliation level, and analyzed forest structure and determined the height-diameter(height means the height of a tree and diameter means the diameter at breast height(DBH) of a tree) relationship of trees in different vitality classes(i.e. healthy, good, medium, senesced, dying, dead and fallen). Trees classified as healthy and good accounted for approximately 40% of all sample trees, while slightly and highly degraded trees took up nearly 60% of total sample trees. The values of TH(tree height) and DBH ranged from 0–19 m and 0–125 cm, respectively. Trees more than 15 m in TH and 60 cm in DBH appeared sporadically. Trees in different vitality classes had different distribution patterns. Healthy trees were mainly composed more of relatively younger trees than of degraded tress. The height-diameter relationships differed greatly among tress in different vitality classes, with the coefficients ranging from 0.1653 to 0.6942. Correlation coefficients of TH and DBH in healthy and good trees were higher than those in trees of other vitality classes. The correlation between TH and DBH decreased with the decline of tree vitality. Our results suggested that it might be able to differentiate degraded P. euphratica trees from healthy trees by determining the height-diameter correlation coefficient, and the coefficient would be a new parameter for detecting degradation and assessing sustainable management of floodplain forests in arid regions. In addition, tree vitality should be taken into account to make an accurate height-diameter model for tree height prediction. 相似文献
205.
Florian?Wichern Christian?Richter Rainer?Georg?JoergensenEmail author 《Biology and Fertility of Soils》2003,37(5):288-294
Soil samples were taken at three depths (0–10, 10–20, 20–30 cm) from an old home garden site, subtropical South Africa (KwaZulu Natal Province), exhibiting symptoms of soil fertility breakdown, and from a new garden site, used formerly as extensive grassland. The aims of our study were to investigate (1) whether soil fertility breakdown is reflected by soil biological indices and (2) whether these indices provide information for improving the situation. The bulk density was significantly larger at the old garden site, with an average of 1.25 g cm-3 in comparison to 1.04 g cm-3 at the new garden site. Also the soil pH was significantly higher at the old garden site, with an average of 5.6 in comparison to 4.0 at the new garden site. Soil organic C and all soil microbial indices declined markedly with depth. If the concentrations were converted to the total amounts stored per hectare at 0- to 30-cm depth, soil organic C was only 10% greater (18.9 versus 17.2 t) at the new garden site, but microbial biomass C was 110% (1,680 vs 790 kg) and ergosterol even 220% greater (5.1 vs 1.6 kg). The microbial biomass C to soil organic C ratio ranged from 0.25% to 1.10%, declined markedly with depth and was almost twice as high at the new garden site. The metabolic quotient qCO2 revealed strong depth-specific variations of between 18 and 38 mg CO2-C day-1 g-1 microbial biomass C at the old garden site on a two to three times higher level than at the new garden site. Soil micro-organisms are much more strongly affected by compaction than by acidification at the present two sites. Whether land use practices led to the increase in bulk density at the old garden site or to the decrease in soil pH at the new garden site is still not fully understood. For these reasons, it is very difficult to recommend a feasible melioration plan. 相似文献
206.
Nicolas Chomrat Elvire Antajan Isabelle Auby Gwenael Bilien Liliane Carpentier Marie-Noëlle de Casamajor Florian Ganthy Fabienne Herv Magali Labadie Claire Mteigner Camille Paradis Myriam Perrire-Rumbe Florence Sanchez Vronique Schet Zouher Amzil 《Marine drugs》2022,20(7)
Blooms of the benthic toxic dinoflagellate genus Ostreopsis have been recorded more frequently during the last two decades, particularly in warm temperate areas such as the Mediterranean Sea. The proliferation of Ostreopsis species may cause deleterious effects on ecosystems and can impact human health through skin contact or aerosol inhalation. In the eastern Atlantic Ocean, the toxic O. cf. ovata has not yet been reported to the north of Portugal, and the only species present further north was O. cf. siamensis, for which the toxic risk is considered low. During summer blooms of unidentified Ostreopsis species on the French Basque coast (Atlantic) in 2020 and 2021, people suffered from irritations and respiratory disorders, and the number of analyzed cases reached 674 in 2021. In order to investigate the causes, sampling was carried out during summer 2021 to (i) taxonomically identify Ostreopsis species present using a molecular approach, (ii) isolate strains from the bloom and culture them, and (iii) characterize the presence of known toxins which may be involved. For the first time, this study reports the presence of both O. cf. siamensis and O. cf. ovata, for which the French Basque coast is a new upper distribution limit. Furthermore, the presence of ovatoxins a, b, c, and d in the environmental sample and in a cultivated strain in culture confirmed the toxic nature of the bloom and allowed identifying O. cf. ovata as the producer. The present data identify a new health risk in the area and highlight the extended distribution of some harmful dinoflagellates, presumably in relation to climate change. 相似文献
207.
Nora M. BiermannNora Rindler MSc Heinz Hans Florian Buchner 《Journal of Equine Veterinary Science》2014
This study assessed the therapeutic effect of pulsed electromagnetic fields (PEMF) on the backs of Polo ponies by measuring mechanical nociceptive thresholds (MNTs) and induced back movement. Twenty Polo ponies in regular training and competition were assigned to two groups. A double-blind, placebo-controlled, crossover field study with PEMF was performed, consisting of two 10-day therapy periods. At the beginning and end of each therapy period, the MNTs from 25 sites of the horses backs were assessed by pressure algometry (PA), and induced back movement was evaluated by flexion testing. Baseline MNTs were generally low, with means between 6.4 and 10.0 kg/cm2. Significant changes in MNTs occurred nearly equally after both the PEMF and the placebo control treatments (at 5 of 25 or 6 of 25 sites, respectively) and without any regular pattern. Changes were evident, predominantly as decreased MNTs within and between treatment periods. Flexion testing revealed stiffness or avoidance in 19 of 20 horses. Results of the flexion testing showed an increased number of physiologic reactions at the end of both treatment periods compared with baseline values. The effect of PEMF on back pain and range of induced back movement could not be proven in this study. Although pretherapy values indicated the horses might have experienced back pain, all horses were still actively used in sport, and back pain might not have been severe enough to allow a significant effect to be demonstrated. 相似文献
208.
209.
Wanner F 《Schweizer Archiv für Tierheilkunde》2011,153(6):295-297
210.
Wanner F 《Schweizer Archiv für Tierheilkunde》2011,153(5):244-245