Spatial and temporal patterns in seed predation as revealed by reciprocal experiments and video surveillance in neighbouring beech and spruce forests     

Vanessa Marie Ellingsen  Johan Asplund 《Scandinavian Journal of Forest Research》2017,32(2):105-114

European beech and Norway spruce are late successional and competitive species meeting each other in southern Norway. Beech is predicted to expand northwards with increased temperature, implying increased competition between the two tree species. Seed survival is a key process in this competition and here we estimate detection times and predation rates of beech and spruce seeds in adjacent beech and spruce forests by combining quantitative and qualitative approaches based on reciprocal seed predation experiments and video surveillance. These experiments were repeated over two growing seasons, and by using a video-surveillance technique, we were able to precisely reveal seed detection times and high seed predation rates, up to 15 seeds?min^?1, with bank vole and chaffinch as main predators. Moreover, the two main predators were different in their seed preferences, that is, beech seeds were exclusively removed or predated by the vole, while the finch consumed spruce seeds only. As we show high predation rates, even small variations in seed predator population densities would impact the regeneration success of beech and spruce. Because the highest predation rates were recorded for spruce seeds, it is likely that this will alter the competitive balance between the two tree species in favour of beech.  相似文献   

Screening of quinalphos,trifluralin and dichlorvos residues in fresh water of aquaculture systems in Mekong Delta,Vietnam     

Quoc Thinh Nguyen  Caroline Douny  Minh Phu Tran  Francois Brose  Phuong Thanh Nguyen  Do Thi Thanh Huong  Patrick Kestemont  Marie‐Louise Scippo 《Aquaculture Research》2019,50(1):247-255

To develop an easy and reliable method for detecting pesticides and their residues in the Mekong Delta, a GC‐MS analytical method was developed and validated according to European guidelines (SANTE/11945/2015) for the determination of residues of three pesticides (quinalphos, trifluralin and dichlorvos) in water. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.002 and 0.007 μg/L, respectively, for quinalphos and trifluralin, and 0.016 and 0.053 μg/L, respectively, for dichlorvos and quinalphos. The repeatability, the within‐laboratory reproducibility as well as the trueness met the European criteria. The recovery rate ranged between 72% (for dichlorvos and quinalphos) and 82% (for trifluralin). The developed method was then applied for the analysis of 33 water samples, collected in April 2013, at the beginning of the rainy season in the Mekong Delta in Vietnam. Thirteen samples were from rice field, 10 were collected from cat fish ponds and from red tilapia cages. Results showed that only 9% of total water samples analysed contained residues of pesticides, but only in water from rice fish systems. From the 13 samples taken in these systems, quinalphos was detected in three samples. The other two pesticides were not detected. A comparison between analytical results obtained from GC‐MS and an alternative method, that is GC‐ECD indicated that GC‐ECD is less sensitive than GC‐MS, with LOQ ranging from 0.37 to 1.18 (depending on the pesticide). However, for samples with concentrations above these LOQ, no significant difference was observed between the results obtained from the two analytical methodologies.  相似文献   

Periphyton characteristics influence the growth and survival of Holothuria scabra early juveniles in an ocean nursery system     

Minin J. Sinsona  Marie Antonette Juinio‐Meez 《Aquaculture Research》2019,50(9):2655-2665

Floating hapas (fine mesh net enclosures) are a cost‐effective ocean nursery system to culture post‐metamorphic Holothuria scabra to release size. The growth of periphyton biofilm on hapas is a natural food source for early juveniles. This study investigated the effects of periphyton quality (i.e. chlorophyll‐a, phaeopigment, total biomass, autotrophic index or AI), water quality (nutrients, chlorophyll‐a) and environmental parameters (temperature, rainfall) on the temporal variation in the growth and survival of early juvenile (~3 mm) H. scabra reared in floating hapas. Five trials where the juveniles were reared for 60 days each in the eutrophic coastal waters of Bolinao, the Philippines were conducted during different months over 2 years. Significant differences in the growth and survival of juveniles among trials were found. Absolute growth rates (AGR) ranged widely (0.01–0.09 g/day). Trials with high AGR of juveniles (0.07–0.09 g/day) during the first 30 days of rearing had significantly higher chlorophyll‐a (chl‐a) in biofilm (15.9–27.5 mg/m²) and lower AI. Conversely, during the subsequent 30 days, trials with high AGR of juveniles (0.06–0.11 g/day) had significantly lower chl‐a and higher AI. Multivariate analyses showed that chl‐a in biofilm, AI and nutrients in the water column are good indicators of periphyton quality and juvenile growth rates in floating hapas. Further, this study validates the expansion of the feeding mode of juveniles from primarily grazing on microalgae, to feeding on detritus and heterotrophs as they grow. These results are important in optimizing ocean nursery systems.  相似文献   

Chemistry of soil organic matter as related to C : N in Norway spruce forest (Picea abies(L.) Karst.) floors and mineral soils     

Marie‐France Dignac  Ingrid Kgel‐Knabner  Kerstin Michel  Egbert Matzner  Heike Knicker 《植物养料与土壤学杂志》2002,165(3):281-289

Due to high nitrogen deposition in central Europe, the C : N ratio of litter and the forest floor has narrowed in the past. This may cause changes in the chemical composition of the soil organic matter. Here we investigate the composition of organic matter in Oh and A horizons of 15 Norway spruce soils with a wide range of C : N ratios. Samples are analyzed with solid‐state ¹³C nuclear magnetic resonance (NMR) spectroscopy, along with chemolytic analyses of lignin, polysaccharides, and amino acid‐N. The data are investigated for functional relationships between C, N contents and C : N ratios by structural analysis. With increasing N content, the concentration of lignin decreases in the Oh horizons, but increases in the A horizons. A negative effect of N on lignin degradation is observed in the mineral soil, but not in the humus layer. In the A horizons non‐phenolic aromatic C compounds accumulate, especially at low N values. At high N levels, N is preferentially incorporated into the amino acid fraction and only to a smaller extent into the non‐hydrolyzable N fraction. High total N concentrations are associated with a higher relative contribution of organic matter of microbial origin.  相似文献   

Roach (<Emphasis Type="Italic">Rutilus rutilus</Emphasis>) reproductive cycle: a study of biochemical and histological parameters in a low contaminated site     

Perrine Geraudie  Marie Gerbron  Elisabeth Hill  Christophe Minier 《Fish physiology and biochemistry》2010,36(3):767-777

Fish reproduction is subjected to worrying trends in many aquatic environments. In this study, we report the absence of histological and biochemical alterations in fish sampled in a low contaminated site (characterised by the absence of detectable oestrogenic activity and mutagenicity in sediment extracts). A total of 474 roach (Rutilus rutilus) were monthly sampled during 18 months, and no intersex fish were recorded after careful histological examination, thus indicating that the incidence of this phenomenon may be very low under natural conditions. Furthermore, mean male plasma vitellogenin concentration was 24 ng ml⁻¹ and was only slightly elevated during the spawning period (up to 120 ng ml⁻¹) indicating that these low values may be characteristic of a low contaminated site. Of the male roach, 45.3% were sampled, a sex-ratio that did not significantly deviated from the expected 1:1 ratio between male and female. Results also showed that natural conditions can greatly affect the reproductive cycle of roach. Gametogenesis showed a biphasic pattern with first gonad maturation between September and December and a final maturation occurring at the end of winter/early spring. Under decreasing temperatures, particularly below 6°C, gametogenesis was stopped or even regressed with secondary oocytes becoming rare under histological observation. Conversely, elevated temperatures during the winter lead to an earlier gonad maturation.  相似文献   

Influence of soil type and water content on release of triticonazole from coated maize seed     

Marie‐Paule Charnay  Christine Verg  Enrique Barriuso 《Pest management science》2000,56(3):249-256

The release of [¹⁴C]triticonazole from coated maize seeds into soil, and its incorporation in maize, were studied under laboratory conditions over seven days in two soils at two different water contents (equivalent to a matrix potential of −3 kPa and −1580 kPa). The behaviour of a commercial coating formulation was compared to that of the same formulation supplemented with a pellicle to improve coated seed handling. Triticonazole released into soil, remaining in the integument and incorporated in different parts of the plant (stem, root, albumen) was measured. The triticonazole released into the soil corresponded to 25% of the initial applied amount on the seed under the best conditions (sandy soil, matrix potential of −3 kPa, set without pellicle). In these conditions, 13% of applied triticonazole was incorporated into roots and stems after seven days. The presence of an additional pellicle to improve the coating decreased the quantity of triticonazole released into soil and consequently the quantity of triticonazole incorporated into the plant. In all cases, the diffusion of triticonazole from the seed to the soil was not limited by the water solubility of triticonazole. Instead, the sorption of triticonazole on soil appears to be the key process governing its fate in soil. © 2000 Society of Chemical Industry  相似文献   

Sublethal effects from endosulfan on parasitization by the parasitoid wasp Leptopilina boulardi and specificity of nervous pathways involved     

Jean‐Marie Delpuech 《Pest management science》2019,75(5):1411-1415

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Polymorphisms in cyanogenic glucoside and cyano‐amino acid content in natural accessions of common vetch (Vicia sativa L.) and selection for improved agronomic performance     

Marwa Aouida  Fred Rook  Alexandra Bianca Maimann  Raquel Snchez‐Prez  Ghassen Abid  Marie Laure Fauconnier  Moez Jebara 《Plant Breeding》2019,138(3):348-359

Common vetch (Vicia sativa L.) is an important annual forage legume. It is used as a cover crop, green manure, pasture legume and for silage and hay production. Its seeds can be used as a source of highly digestible protein and minerals in animal diets. However, their utilization as a feedstuff for monogastric animals is hindered by the fact that the seeds contain cyanogenic antinutritional factors that reduce their palatability. An effective utilization of V. sativa seeds as a successful monogastric feed stuff requires selection for higher protein availability and minimization of the cyanogenic antinutritional factors content. In this study, we selected one natural accession named Mjez Ibeb, from a collection of 25 accessions and cultivars, based on its superior agronomic performance and its naturally occurring genetic variation for cyanogenic traits. We investigated the genetic variation that exists for the cyanogenesis trait in more detail and analysed the seeds of 133 lines derived from accession Mjez lbeb. Of these, 40 naturally polymorphic lines that showed deficiencies in cyanogenesis and cyano‐amino acid content, were subsequently selected for detailed chemical analysis. Cyanogenic glucosides and cyano‐amino acid concentrations varied widely in the 40 lines. Multivariate analysis was performed and three lines (L₁₆, L₂₁, L₁₈) with low content of cyanogenic compounds were identified.  相似文献   

Intensive versus low-input cropping systems: What is the optimal partitioning of agricultural area in order to reduce pesticide use while maintaining productivity?   总被引：1，自引：0，他引：1  

Marie Gosme  Frédéric Suffert 《Agricultural Systems》2010,103(2):110-116

Pesticide use should be reduced for sustainable agriculture. Low-input cropping systems, centered on hardy varieties that maintain their yield in the presence of pests, allow pesticide use to be reduced. Since yield potential is generally lower for hardy varieties than for high-yielding varieties, a balance must be found between production and pesticide reduction. In order to compute the optimal partitioning of agricultural area between intensive and low-input cropping systems, we present a model that allows yield and gross margins to be computed at the landscape scale, as a function of the proportion of the area under intensive and low-input systems. The model shows that two cases must be distinguished, depending on inoculum production by each of the coexisting systems. If the low-input system produces less inoculum (e.g. because resistant varieties are used), coexistence can be optimal, whereas if the low-input system produces more inoculum (e.g. because tolerant varieties are used), it is best to devote the whole area to a single system. The model gives the gross margin for each cropping system as a function of the proportion of low-input systems - and so predicts the proportion to which the farmers’ choices will lead - and illustrates the use of different (simplified) policies that would ensure that the optimum proportion is reached.  相似文献   

Caroubin: A Gluten-like Protein Isolated from Carob Bean Germ     

Pierre Feillet  Thrse Marie Roulland 《Cereal Chemistry》1998,75(4):488-492

In 1935, Bienenstock and coworkers claimed the presence of gluten-like material in the germ of the carob seed. The viscoelastic properties of the water-insoluble proteins isolated from carob germ, which we propose to call caroubin, have been confirmed by dynamic (G′ and G″) and static rheological measurements (texture profile analysis, viscoelastogram). Biochemical analyses showed important similarities (high glutamic acid content, size-exclusion HPLC profile, PAGE patterns of reduced and unreduced proteins) as well as large differences (high arginine and low cysteine and proline content of caroubin, carbohydrate composition) between caroubin and wheat gluten. Besides potential new industrial uses of carob seed, caroubin could be a valuable material to help us understand the physicochemical basis of the viscoelastic properties of plant protein complexes like wheat gluten.  相似文献