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31.
A vineyard of Vitis vinifera cv. Sangiovese was surveyed for incidence of esca and xylem sap collection. Sap samples were collected from healthy vines and from those with dual infection by Phaeomoniella chlamydospora (Pch) and Togninia minima (Tmi) or triple infection by Pch, Tmi and Fomitiporia mediterranea (Fme), during each early spring in a 3-year period (2001–2003). In order to analyse the possible trends in the climatic data, temperature and rainfall were assessed. At sap harvesting, aliquots of sap were assayed for phytotoxicity and extracted with ethyl acetate for phytotoxin recovery. Moreover, the exopolysaccharide (EPS) content was evaluated on several sap samples during the bleeding period. Conidia of Pch and Tmi, mycelium of Fme and their secondary metabolites were found in the sap of the esca-affected vines, indicating that the pathogens and their by-products together with some defence substances were accumulated and then translocated. Bioactivity tests showed toxicity of the sap from esca-affected vines to healthy detached leaves of cv. Sangiovese. The daily amount of sap, the pH, and the volume (Jv) and solute (Js) fluxes were analysed as a function of the infecting fungi. Pullulan, glucogalactomannan(s) and arabinogalactan(s) are the main EPS in the esca-infected vines, whereas in the sap of healthy vines no traces of pullulan were found. Scytalone and isosclerone usually produced in vitro by Pch and Tmi were also detected in the sap of vines infected by Pch and Tmi or by Pch, Tmi and Fme. The endogenous phytohormone content of healthy vines evaluated by the cutting bioassay was different from that of infected vines. Four phenolics belonging to three classes e.g., benzoic acid derivatives, stilbenes and flavonol-glycosides were separated and identified by HPLC.  相似文献   
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33.

Key message

Aggregated, consolidated, and derived soil physicochemical data of 286 ICP Forests Level II plots were completed with soil hydraulic properties for integrated use with forest monitoring data. Database access should be requested at http://icp-forests.net . Metadata associated available at https://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=153e599e-6624-4e2b-b862-8124386ea9cd&hl=eng

Context

The ICP Forests database is one of the most comprehensive forest ecosystem datasets in Europe and contains the accumulated results of more than two decades of harmonised forest monitoring all over Europe.

Aims

The aim of this paper is to share knowledge on the ICP Forests Level II soil data for broader use among forest scientists.

Methods

After standard analysis, quality checks, aggregation, and calculation of derived variables (e.g. nutrient stocks, base saturation, C:N ratio, and water retention parameters), data have been gathered into a static database (AFSCDB.LII.2.2), which will be updated to new versions as soon as new measurements become available.

Results

The database provides a basis for the combined evaluation of up to 130 unique soil variables of 286 plots with dynamic data on tree growth, ground vegetation, foliar chemistry, crown condition, tree phenology, leaf area index, ozone injury, litterfall, soil solution chemistry, deposition, ambient air quality, and meteorological data assessed on the same plots.

Conclusion

The unprecedented comprehensiveness and level of detail in this newly aggregated database may overcome existing restrictions so far impeding the realisation of large-scale forest ecosystem studies in Europe.
  相似文献   
34.
The Columbia root-knot nematode (CRKN), Meloidogyne chitwoodi, is an EPPO A2 type quarantine pest since 1998. This nematode causes severe damage in economically important crops such as potato and tomato, making agricultural products unacceptable for the fresh market and food processing. Commonly used nematicidal synthetic chemicals are often environmentally unsafe. Essential oils (EOs) may constitute safer alternatives against RKN. EOs, isolated from 56 plant samples, were tested against CRKN hatching, in direct contact bioassays. Some of the most successful EOs were fractionated and the hydrocarbon molecules (HM) and oxygen-containing molecules (OCM) fractions tested separately. 24 EOs displayed very strong hatching inhibitions (≥90 %) at 2 µL mL?1 and were further tested at lower concentrations. Dysphaniaambrosioides, Filipendula ulmaria, Ruta graveolens, Satureja montana and Thymbra capitata EOs revealed the lowest EC50 values (<0.15 µL mL?1). The main compounds of these EOs, namely 2-undecanone, ascaridol, carvacrol, isoascaridol, methyl salicylate, p-cymene and/or γ-terpinene, were putatively considered responsible for CRKN hatching inhibition. S. montana and T. capitata OCM fractions showed hatching inhibitions higher than HM fractions. The comparison of EO and corresponding fractions EC50 values suggests interactions between OCM and HM fractions against CRKN hatching. These species EOs showed to be potential environmentally friendly CRKN hatching inhibitors; nonetheless, bioactivity should be considered globally, since its HM and OCM fractions may contribute, diversely, to the full anti-hatching activity.  相似文献   
35.
Transverse drying shrinkage was measured at microscopic and mesoscopic levels in poplar wood characterised by an increasing growth strain (GS), from normal to tension wood. Results show that: (a) the drying shrinkage, measured as a relative thickness decrease, was significantly higher for G-layer (GL) than for the other layers (OL), GL shrinkage was not significantly correlated with GS, and OL shrinkage was negatively correlated with GS. (b) In gelatinous fibre (G-fibre), lumen size increased during drying and this increase was positively related with GS, but in normal wood fibre, lumen size decreased during drying. These findings suggest that GL shrank outwards (i.e., its internal perimeter increases), so that its shrinkage weakly affected the total cell shrinkage and the mesoscopic shrinkage was controlled by the OL shrinkage which shrank inwards (i.e., its external perimeter decreases). (c) Measurements done on 7 × 7 mm2 thin sections evidenced a negative correlation between transverse shrinkage and GS, significant in T direction but weak in R direction. These observations at both levels allow to discuss the contribution of GL to the mesoscopic shrinkage of tension wood.  相似文献   
36.
Phenological stages are the result of biorhythms and environmental factors, these last are probably the same ones that caused, during evolution, adjustments of the species to different climate. The present study was carried out in a Phenological Garden located in central Italy (Perugia, Umbria Region) which contains indicator species, common to all International Phenological Gardens. The aim of this study was to determine and analyse the average trends of development of eight plant species and their phenological adjustment to the Mediterranean environment, over a nine-year period (1997–2005). The results of the statistical analyses show a strong relationship between the temperature trends and vegetative seasonal evolutions interpreted by phenological data for all the species considered. Moreover, it was demonstrated that the plants studied may approach or close completely the timing gaps eventually created during the first phenological phases, adjusting thus the beginning of subsequent phenophases.  相似文献   
37.
Taking advantage of the introduction of the black-tailed deer to the Queen Charlotte Islands (British Columbia, Canada), we used dendrochronological analyses to understand the consequences of deer browsing on Sitka spruce growth. We compared shape, radial growth, height growth and age of young spruce in three sites. We identified two types of trees growing side by side: (1) stunted and heavily browsed spruce, smaller than the browsing limit and (2) escaped spruce that were taller than the browsing limit but still browsed in their lower part. The compact and heavily ramified shape in stunted spruce was the result of repeated and intense browsing. In escaped spruce this was also the case below the browsing limit (1.16 m±0.07 m), in sharp contrast with the normal shape that escaped spruce resumed above the browsing limit. We show that the release of browsing pressure, once the tree reaches the browsing limit, is characterised by an abrupt increase in radial growth. Before release, trees show a growth stagnation characterized by narrow rings (0.5 mm per year) and small annual height increments (<5 cm per year). After release, trees show a growth stabilisation characterised by wider rings (3 mm per year) and larger annual height increments (20 cm per year). We use this pattern to estimate frequency and age at release and their possible variation over time. Age differences between stunted and escaped spruce are highly significant and indicate that, despite of browsing, most if not all trees will ultimately reach the browsing limit and escape. Heavy deer pressure (30 deer per km2) delays spruce sapling recruitment by about 8 years. This delay varies in relation to site quality and seems to have increased over time, suggesting an increase in browsing pressure.  相似文献   
38.
It has been postulated that osmotic effects on plant tissue are mediated by abscisic acid (ABA). Hybrid larch (Larix kaempferi (Lambert) Carr. x L. decidua Mill.) plantlets, transformed with the ABA-inducible wheat Em promoter associated with the Gus reporter gene, were axenically inoculated with two ectomycorrhizal fungi: Cenococcum geophilum Fr., considered tolerant to water stress, and Laccaria bicolor (Marie) Orton, considered less tolerant to drought. The mycorrhizal and non-mycorrhizal transgenic plantlets were subjected to osmotic stress by adding polyethylene glycol (PEG) to the culture medium. In the presence of PEG, L. bicolor and C. geophilum reduced shoot water potential and turgor potential, but increased host osmotic potential. Treatment of plantlets with PEG induced a significant increase in endogenous ABA concentrations. Laccaria bicolor and C. geophilum behaved similarly and significantly decreased the ABA response of plantlets to PEG treatment. Moreover, inoculation with either fungus regulated the ABA response of the plantlets even when the fungus was separated from the host by a cellophane sheet that prevented mycorrhiza formation. Although the wheat Em promoter was inducible in larch plantlets, it was not regulated by endogenous ABA. Induction of the wheat Em promoter in larch plantlets depended on organ type, with maximum induction in the root apex. Induction of the Em promoter was significantly decreased by mycorrhizal inoculation.  相似文献   
39.

Ovine and caprine stockbreeding have been gaining attention in developing countries as an attractive investment. On these animals, infectious diseases of the reproductive tract, such as leptospirosis, can compromise the production leading to economic losses. The present study aimed to determine the risk factors associated with incidental leptospirosis and its influence on the reproductive parameters of ewes and goats of Espírito Santo state, Brazil. A total of 737 animals distributed on 24 herds/flocks were studied, and an overall prevalence of 10.9 % seroreactive animals was observed. Serogroup Icterohaemorrhagiae was the most frequent in goats (97.0 %) as well as in ewes (78.3 %). Regarding risk factors related to leptospirosis, the presence of waterholes and the semi-intensive breeding system were the most important associated to seroreactivity. Besides, there was an observed association between seroreactivity and reproductive failures (P?<?0.05). Moreover, seroreactive ewes (relative risk (RR)?=?1.3) and goats (RR?=?1.9) presented more chances to have abortions than seronegative animals. Furthermore, seroreactive ewes presented 11.6 more chances of having premature births when compared to the seronegative ones. It can be concluded that Leptospira infection, mainly those caused incidental strains (such as Icterohaemorrhagiae serogroup), is a significant factor to reduce the productivity of small ruminants’ herds/flocks in the studied region, and environmental measures must be considered on control programs.

  相似文献   
40.
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