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21.
We have examined the effect of Pen, an aqueous extract of the dry mycelium of Penicillium chrysogenum, on plant–pathogen interactions. Pen controlled a broad range of pathogens on several crop plants under greenhouse and field conditions. Pen protected grapevine from downy and powdery mildew (caused by Plasmopara viticola and Uncinula necator), tomato from early blight (caused by Phytophthora infestans), onion from downy mildew (Peronospora destructor) and apple trees from apple scab (caused by Venturia inaequalis) to a similar extent as fungicides such as copper and sulphur or well-known inducers such as benzothiadiazole or β-aminobutyric acid. Pen had no major direct fungicidal effect and is thus supposed to protect plants by activating their defense mechanisms. The raw material for extraction of Pen was available in constant quality, a prerequisite for commercial application. Under certain conditions, Pen caused phytotoxic side effects. The symptoms mostly consisted of small necrotic spots or, more rarely, of larger necrotic areas. The development of the symptoms was dependent on several parameters, including concentration of Pen, the number of applications, the persistence on the plant tissue, the plant species and variety and environmental conditions. In grapevine, a partially purified fraction of Pen was much less toxic than the crude Pen extract, but protected the plants to a similar extent against P. viticola. Our data show that Pen has interesting and unique properties as a plant protection agent, but more research is needed to further reduce its phytotoxic side effects.  相似文献   
22.
We studied stomatal responses to decreasing predawn water potential (Psipd) and increasing leaf-to-air water vapor pressure difference (VPD) of co-occurring woody Mediterranean species with contrasting leaf habits and growth form. The species included two evergreen oaks (Quercus ilex subsp. ballota (Desf.) Samp. and Q. suber L.), two deciduous oaks (Q. faginea Lam. and Q. pyrenaica Willd.) and two deciduous shrubs (Pyrus bourgaeana Decne. and Crataegus monogyna Jacq.). Our main objective was to determine if stomatal sensitivity is related to differences in leaf life span and leaf habit. The deciduous shrubs had the least conservative water-use characteristics, with relatively high stomatal conductance and low stomatal sensitivity to soil and atmospheric drought. As a result, Psipd decreased greatly in both species during the growing season, resulting in early leaf abscission in the summer. The deciduous oaks showed intermediate water-use characteristics, having maximum stomatal conductances and CO2 assimilation rates similar to or even higher than those of the deciduous shrubs. However, they had greater stomatal sensitivity to soil drying and showed less negative Psipd values than the deciduous shrubs. The evergreen oaks, and especially the species with the greatest leaf longevity, Q. ilex, exhibited the most conservative water-use behavior, having lower maximum stomatal conductances and greater sensitivity to VPD than the deciduous species. As a result, Psipd decreased less during the growing season in the evergreens than in the deciduous species, which may contribute to greater leaf longevity by avoiding irreversible damage during the summer drought. However, the combination of low maximum CO2 assimilation rates and high stomatal sensitivity to drought must have a negative impact on the final carbon budget of leaves with a long life span.  相似文献   
23.
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   
24.
ABSTRACT

Applied behavior analysis can be used by development practitioners to improve the design and implementation of development programs. Programs are most successful when the goals and consequences of change agents, strategists, and adopters align, as we demonstrate with real-world examples from international agroforestry projects. We focus on the role of change agents acting as intermediaries between change strategists, such as large development agencies, and development adopters, the rural farmers who implement agroforestry projects. We describe three aspects that are particularly important for agroforestry projects: (1) identifying the rules being used, (2) assessing the roles and reinforcement contingencies of both individuals and larger groups, and (3) being flexible and able to respond to rapid change.  相似文献   
25.
Field-grown olive trees (Olea europaea L. cv. Leccino) were used over two growing seasons to determine the effect of deficit irrigation regimes on virgin olive oil (VOO) quality. Drip irrigation was managed to maintain a predawn leaf water potential (PLWP): (a) higher than -1.1 MPa (full irrigation: FI); (b) between -1.0 and -3.3 MPa (deficit irrigation: DI); (c) higher than -4.2 MPa (severe deficit irrigation: SI). The fruit yield and oil yield of DI trees were over 90% of those of FI treatments in both years, respectively, whereas yields of SI trees ranged from 61 to 76%. The irrigation regime had minor effects on the free acidity, peroxide value, and fatty acid composition of VOO. The concentrations of phenols and o-diphenols in VOO were negatively correlated with PLWP. The concentrations of the dialdehydic form of decarboxymethyl elenolic acid linked to (3,4-dihydroxyphenyl)ethanol (3,4-DHPEA-EDA), the isomer of the oleuropein aglycon (3,4-DHPEA-EA), and the dialdehydic form of decarboxymethyl elenolic acid linked to (p-hydroxyphenyl)ethanol (p-HPEA-EDA) were lower in FI than in SI treatments. The concentrations of lignans (+)-1-acetoxipinoresinol and (+)-1-pinoresinol were unaffected by the irrigation regime. The tree water status had a marked effect on the concentration of volatile compounds, such as the C(6)-saturated and unsaturated aldehydes, alcohols, and esters.  相似文献   
26.
On the basis of the biological activities exhibited by the phenolic constituents of Yucca schidigera, the antioxidant activity of the methanol extract of Yucca gloriosa roots was evaluated in the TEAC assay. The strong activity exerted by this extract prompted investigation of its phenolic constituents, yielding three new phenolic derivatives, gloriosaols C, D, and E, along with gloriosaols A and B previously isolated from Y. gloriosa roots and yuccaols C-E isolated from Y. schidigera. ESIMS and NMR data of gloriosaols C-E closely resembled those reported for gloriosaols A and B, two diasteroisomers characterized by unusual spirostructures. Careful inspection of ROESY spectra revealed that gloriosaols C-E are diastereoisomers of gloriosaols A and B. A possible assignment of the relative configuration of gloriosaols C-E, derived according to an integrated NMR-quantum mechanical (QM) approach, which was already applied to the determination of the stereostructures of gloriosaols A and B, is also proposed. Gloriosaols A-E exhibited potent antioxidant activity measured by the TEAC assay, showing the potential use of Y. gloriosa as a source of antioxidant principles.  相似文献   
27.
In this paper lipoxygenase (LOX) presence was investigated in coffee berries to determine its involvement in lipid degradative metabolism of plants grown in organic and conventional cultivations. An immunochemical analysis has evidenced a ca. 80 kDa protein, cross-reacting with an anti-LOX antibody, only in the pulp fraction of berries obtained from plants of both cultivations. LOX activity in this fraction could be monitored either as conjugated diene formation or reaction products (determined by HPLC) and was mainly associated with a heavy membrane fraction (HMF, enriched in tonoplast, endoplasmic reticulum, plasma membrane, and mitochondria) and a light membrane fraction (LMF, enriched in plasma membrane and endoplasmic reticulum, with low levels of tonoplast and mitochondria). The LOX activity of LMF from berries of both cultivations showed an optimum at pH 8.0. The HMF exhibited a different activity peak in samples from conventional (pH 8.0) and organic (pH 5.5) cultures, suggesting the presence of different isoenzymes. These findings were also confirmed by variation of the ratio of 9- and 13-hydroperoxides in organic (1:1) and conventional cultivations (1:10), indicating that the organic one was subjected to an oxidative stress in the coffee pulp fraction leading to the expression of an acidic LOX. Such de novo synthesized LOX activity could be responsible for the production of secondary metabolites, which may interfere with the organoleptic profile of coffee.  相似文献   
28.
This study documents the degree of positional atelectasis in sedated dogs receiving 100% oxygen (O2) versus room air. Initial lateral recumbency was determined by an orthopedic study and initial treatment (O2 or room air) was randomized. Each dog was maintained in lateral recumbency for 15 min, at which time ventrodorsal (VD) and opposite lateral thoracic radiographs were obtained. Each dog was then maintained in the opposite lateral recumbency and received the other treatment for 15 min, followed by a VD and opposite lateral radiograph. Radiographs were scored for severity of pulmonary pattern and mediastinal shift by 3 radiologists. Dogs breathing O2 had significantly higher scores than dogs breathing room air. If radiographically detectable dependent atelectasis is present, repeat thoracic images following manual positive ventilation and/or position change to the opposite lateral recumbency should be made to rule out the effect of O2 positional atelectasis and avoid misdiagnosis.  相似文献   
29.
Long pentraxin 3 (PTX3) is a conserved pattern-recognition secreted protein and a host-defence-related component of the humoral innate immune system. The aim of the present study was to characterize swine PTX3 (SwPTX3) protein expression in influenza virus infected pigs. First, we performed in silico studies to evaluate the cross-reactivity of PTX3 human antibodies against SwPTX3. Secondly, we used in vitro analysis to detect SwPTX3 presence in swine bone marrow dendritic cells (SwBMDC) upon stimulation with different agents by Western blot and immunofluorescence. Finally, the levels of SwPTX3 were assessed in experimental infection of pigs with different strains of influenza virus. This is a novel study where the expression of SwPTX3 was evaluated in the context of a pathogen infection. The initial characterization of SwPTX3 in influenza virus infected pigs contributes to understand the role of PTX proteins in the immune response.  相似文献   
30.
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