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排序方式: 共有542条查询结果,搜索用时 15 毫秒
101.
102.
Edyta Wojciechowska Christoph H. Weinert Björn Egert Bernhard Trierweiler Markus Schmidt-Heydt Bernd Horneburg Simone Graeff-Hönninger Sabine E. Kulling Rolf Geisen 《European journal of plant pathology / European Foundation for Plant Pathology》2014,139(4):735-747
Tomato fruits can be contaminated by saprophytic strains of Alternaria alternata which is the reason for the frequent occurrence of Alternaria toxins like alternariol, alternariol monomethylether or tenuazonic acid in these types of products. It was shown earlier that alternariol is a colonization factor for tomatoes. In the current analysis two different tomato genotypes were analysed by untargeted comprehensive two-dimensional gas chromatography mass spectrometry (GC×GC-MS). This analysis revealed clear differences in the metabolic profiles which were paralleled by differences in resistance towards Alternaria colonization. One of the genotypes was more resistant against A. alternata infection and contained high amounts of chlorogenic acid in contrast to the other genotype which was sensitive against infection. In in vitro analysis, chlorogenic acid reduced alternariol biosynthesis during the first days of growth of A. alternata. Expression analysis of the alternariol polyketide synthase gene, a key gene in the biosynthesis of alternariol, also revealed a temporal reduction in its expression in the first phases of growth. However by chromatographic analysis it could be demonstrated that chlorogenic acid was degraded over time. This degradation leads to a relief of inhibition resulting in an only temporal inhibition of alternariol biosynthesis. In vivo colonization experiments revealed that chlorogenic acid reduces colonization of tomatoes by A. alternata in a concentration dependent manner, which however is partly counteracted by the addition of alterariol. 相似文献
103.
Organic acids released into the rhizosphere may perform many beneficial functions to the plant including metal detoxification and enhancement of nutrient acquisition. Typically, these organic acids are studied in isolation; however, roots simultaneously exude a cocktail of organic acids and other substances, and their combined impact on rhizosphere processes may be quite different. It has been hypothesized that some exudates may play secondary roles (e.g. inhibitors of microbial activity, blockage of sorption sites), which might enhance the longevity and nutrient-mobilization capacity of others. Here we investigated how the decomposition, sorption and P-solubilizing effects of citrate, malate and oxalate are affected by the presence of malonate and shikimate. We found that in a range of agricultural soils the decomposition of citrate, malate and oxalate was rapid, but not influenced by the presence of large quantities of shikimate or malonate. This suggests that the individual organic acids are taken up by different transport mechanisms or components of the microbial community. At large concentrations, malonate decreased sorption of citrate, malate and oxalate on the soil, whilst shikimate had little effect. The capacity of citrate, malate and oxalate to desorb P was significantly greater in cocktails containing malonate compared with the single organic acid; no effect was seen with shikimate. We conclude that neither malonate nor shikimate at realistic concentrations will significantly affect the biodegradation of citrate, malate or oxalate in the rhizosphere, and while malonate did enhance P desorption, this effect is additive rather than synergistic. Overall, we found little evidence that malonate and shikimate act as secondary regulators of citrate, malate and oxalate behavior in soil. 相似文献
104.
It is generally recognized that roads can adversely affect local animal populations but little is known how roads affect bats. In particular, no study compared the response of bats that differ in foraging ecology to motorways that cut through the breeding habitat. As bats are key species in conservation, such data are urgently needed for designing management plans. Using radio-telemetry, mist netting, and mark-recapture data we investigated the effects of a motorway with heavy traffic on the habitat use of two threatened forest-living bats. We compared barbastelle bats (Barbastella barbastellus), which forage in open space, to Bechstein’s bats (Myotis bechsteinii), which glean prey from the vegetation. Five of six radio-tracked barbastelle bats crossed the motorway during foraging and roost switching, flying through underpasses and directly over the motorway. In contrast, only three of 34 radio-tracked Bechstein’s bats crossed the motorway during foraging, all three using an underpass. Bechstein’s bats, unlike barbastelle bats, never crossed the motorway during roost switching. Moreover, only in Bechstein’s bats individuals foraging close to the motorway had smaller foraging areas than individuals foraging further away, whereas other forest edges had no such effect. Our data show that motorways can restrict habitat accessibility for bats but the effect seems to depend on the species’ foraging ecology and wing morphology. We suggest that motorways have stronger barrier effects on bats that forage close to surfaces than on bats that forage in open space, and discuss the implications of our findings for bat conservation during road construction. 相似文献
105.
Tineke Slootweg Michel Alvinerie Philipp Egeler Daniel Gilberg Jussi V. K. Kukkonen Jörg Oehlmann Carsten Prasse Arto J. Sormunen Markus Liebig 《Journal of Soils and Sediments》2010,10(8):1611-1622
Purpose
Although ivermectin is a widely used lipophilic parasiticide, data on its potential bioaccumulation in aquatic invertebrates are scarce. In this study, bioaccumulation patterns of radiolabeled 3H-ivermectin from sediments into tissues of the sediment-dwelling worm Lumbriculus variegatus were investigated and assessed. 相似文献106.
Samuli Junttila Mikko Vastaranta Jarno Hämäläinen Petri Latva-käyrä Markus Holopainen Rocío Hernández Clemente 《Scandinavian Journal of Forest Research》2017,32(2):154-165
The effect of forest structure and health on the relative surface temperature captured by airborne thermal imagery was investigated in Norway Spruce-dominated stands in Southern Finland. Airborne thermal imagery, airborne scanning light detection and ranging (LiDAR) data and 92 field-measured sample plots were acquired at the area of interest. The surface temperature correlated most negatively with the logarithm of stem volume, Lorey’s height and the logarithm of basal area at a resolution of 254?m2 (9?m radius). LiDAR-derived metrics: the standard deviations of the canopy heights, canopy height (upper percentiles and maximum height) and canopy cover percentage were most strongly negatively correlated with the surface temperature. Although forest structure has an effect on the detected surface temperature, higher temperatures were detected in severely defoliated canopies and the difference was statistically significant. We also found that the surface temperature differences between the segmented canopy and the entire plot were greater in the defoliated plots, indicating that thermal images may also provide some additional information for classifying forests health status. Based on our results, the effects of forest structure on the surface temperature captured by airborne thermal imagery should be taken into account when developing forest health mapping applications using thermal imagery. 相似文献
107.
Markus Holopainen Antti Mäkinen Jussi Rasinmäki Juha Hyyppä Hannu Hyyppä Harri Kaartinen Risto Viitala Mikko Vastaranta Annika Kangas 《European Journal of Forest Research》2010,129(5):899-907
The objective was to compare tree-level airborne laser-scanning (ALS) data accuracy with standwise estimation data accuracy
as input data for forest planning, using tree- and stand-level simulators. The influence of the input data accuracy was studied
with respect to (1) timing of the next thinning or clear-cutting and (2) the relative variation in the predicted income of
the next logging expressed as the net present value (NPV). The timing and predicted NPV of thinning and clear-cutting operations
were considered separately. The research was based on Monte Carlo simulations carried out with the tree- and stand-level simulators
using a simulation and optimisation (SIMO) framework. The simulations used treewise measurements taken on 270 circular plots
measured at the Evo Field Station, Finland, as input data. Deviations in the tree data measured were generated according to
the mean standard errors found in standwise field estimation and tree-level ALS. The accuracy factors of ALS individual tree
detection were based on the EUROSDR/ISPRS Tree Extraction Project. The results show that input data accuracy significantly
affects both the timing and relative NPV of loggings. Tree-level ALS produces more accurate simulation results than standwise
estimation with the error levels assumed. Diameter-based characteristics are the most important input data in all simulations.
Accurate tree height estimates cannot be fully utilised in current simulators. 相似文献
108.
Antti Mäkinen Markus Holopainen Annika Kangas Jussi Rasinmäki 《European Journal of Forest Research》2010,129(5):887-897
Developments in the field of remote sensing have led to various cost-efficient forest inventory methods at different levels
of detail. Remote-sensing techniques such as airborne laser scanning (ALS) and digital photogrammetry are becoming feasible
alternatives for providing data for forest planning. Forest-planning systems are used to determine the future harvests and
silvicultural operations. Input data errors affect the forest growth projections and these effects are dependent on the magnitude
of the error. Our objective in this study was to determine how the errors typical to different inventory methods affect forest
growth projections at individual stand level during a planning period of 30 years. Another objective was to examine how the
errors in input data behave when different types of growth simulators are used. The inventory methods we compared in this
study were stand-wise field inventory and single-tree ALS. To study the differences between growth models, we compared two
forest simulators consisting of either distance-independent tree-level models or stand-level models. The data in this study
covered a 2,000-ha forest area in southern Finland, including 240 sample plots with individually measured trees. The analysis
was conducted with Monte Carlo simulations. The results show that the tree-level simulator is less sensitive to errors in
the input data and that by using single-tree ALS data, more precise growth projections can be obtained than using stand-wise
field inventory data. 相似文献
109.
Michael Rodgers Mark O’Connor Mark Gerard Healy Connie O’Driscoll Zaki-ul-Zaman Asam Mika Nieminen Russell Poole Markus Müller Liwen Xiao 《Forest Ecology and Management》2010
The aim of this study was to investigate the release of phosphorus (P) to receiving waters resulting from harvesting 34-year-old lodgepole pine trees in an upland peat catchment. The study site was within a 25.3-hectare (ha) area, and was drained by a stream that received flows from ploughed furrows, mainly, via collector drains, and discharged directly to the salmonid Shrahrevagh River, Burrishoole, Co. Mayo, Ireland. The study site was divided into two parts: the upstream part was left intact and the downstream part was harvested in early Autumn 2005 following implementation of forest guidelines. Good management practices such as proper use of brash mats and harvesting only in dry weather were implemented. Two instrumented stations were established – one just upstream (US) and the other just downstream (DS) of the clearfelled area. The measurement of P concentrations at the two stations commenced in May 2005, two months before the harvesting started. The daily mean P concentration at the DS station increased from about 6 μg L−1 of total reactive phosphorus (TRP) during pre-clearfelling to 429 μg L−1 in August 2006. By October 2009, four years after clearfelling, the P concentrations at the DS station had returned to pre-clearfelling levels. In the first three years after harvesting, up to 5.15 kg ha−1 of TRP was released from the harvested catchment to the receiving water; in the second year alone, 2.3 kg ha−1 of TRP was released. Linear regression can be used to describe the relationship between TRP load and water discharge. About 80% of the total phosphorus (TP) in the study stream was soluble and more than 70% of the P release occurred in storm events, indicating that traditional buffer strips with widths of 15–20 m might not be efficient for P immobilization. The P concentrations were affected by antecedent weather conditions and highest concentrations occurred during storm events following prolonged drought periods. The water extractable phosphorus (WEP) contents in the soil were significantly higher below windrow/brash material than in brash-free areas, and whole-tree harvesting should be studied as one of the means to decrease P export from blanket peats. 相似文献
110.