Epigeic earthworms increase soil arthropod populations during first steps of decomposition of organic matter     

Fernando Monroy  Manuel Aira  Jorge Domínguez 《Pedobiologia》2011,54(2):93-99

Earthworms and soil arthropods are major groups involved in soil decomposition processes. Although the interaction between these organisms can influence decomposition rates, little is known about their population dynamics during the decomposition of organic matter. In this study, we used the pig manure decomposition process to evaluate the effects of the presence of the epigeic earthworm Eisenia fetida on seven groups of soil arthropods: springtails, astigmatid, prostigmatid, mesostigmatid and oribatid mites, psocids and spiders. We carried out an experiment in which low and high doses (1.5 and 3 kg, respectively) of pig manure were applied in consecutive layers to small-scale mesocosms with and without earthworms. The presence of E. fetida increased the overall number of soil arthropods regardless of the dose of manure applied. This result was mainly due to the presence of large populations of springtails and mesostigmatid mites. Springtails were more abundant in the new layers of the mesocosms, which indicated a preference for substrates with fresh organic matter and higher microbial biomass. The other arthropod groups were consistently favored by the presence of earthworms, but remained at low densities throughout the decomposition process. Only the psocids were negatively affected by the presence of E. fetida. These results suggest that the development of large populations of soil arthropods, mainly springtails, in the mesocosms with earthworms is a characteristic feature of the initial stages of the earthworm-driven decomposition process.  相似文献   

Depolymerization and mineralization rates at 12 Mediterranean sites with varying soil N availability. A test for the Schimel and Bennett model     

Manuel Delgado-Baquerizo  Antonio Gallardo 《Soil biology & biochemistry》2011,43(3):693-696

It has been suggested that the relative abundance of soil nitrogen forms should change along an N availability gradient. This model was originally described at a biome scale, and few studies have tested it at other scales. Moreover, none of them has examined whether changes in the relative rates of ammonification, nitrification and depolymerization rates also occurs. Our goal was to test whether these N transformation rates change along an N availability gradient which is likely to exist between forest, shrubs and grasses. We used three N availability indexes (total K₂SO₄-extractable N, ion exchange membrane N and the sum of N mineralization and depolymerization rates). Depolymerization dominated over mineralization in the two poorest plant communities, while ammonification and nitrification rates dominated in intermediate and nutrient rich plant communities respectively. These results confirm that the Schimel and Bennett model can be applied at a regional scale, and that N availability may be modulating not only the dominant N form, but also the relative abundance of a particular N transformation rate.  相似文献   

Identification and thermal degradation kinetics of chlorophyll pigments and ascorbic acid from ditax nectar (Detarium senegalense J.F. Gmel)     

Diop Ndiaye N  Dhuique-Mayer C  Cisse M  Dornier M 《Journal of agricultural and food chemistry》2011,59(22):12018-12027

Detarium senegalense J.F. Gmel (ditax) is a forest tree found in Senegal the fruits of which are characterized by an attractive green flesh with a high amount in ascorbic acid. It is generally consumed as a nectar in Senegal. In this study, the main pigments of ditax pulp were identified and quantified by HPLC-DAD. Pheophytin a (128 mg/kg), which represents 58% of the total pigments, followed by hydroxypheophytin a' (33 mg/kg), chlorophyll b (24 mg/kg), and chlorophyll a (20 mg/kg) was the major pigment of ditax pulp. Lutein and β-carotene were present in lower amounts (4.6 and 3.6 mg/kg, respectively). The thermal degradation kinetics of pheophytin a, hydroxypheophytin a', and ascorbic acid were determined at temperatures ranging from 60 to 95 °C in ditax nectar. Pheophytin a was the most heat sensitive. Thermal processing induced the formation of degradation products such as pyropheophytin a and pyropheophytin b. The kinetics parameters have been calculated according to the models of Arrhenius, Eyring, and Ball. Following the Arrhenius relation, activation energies of pheophytin a, hydroxypheophytin a', and ascorbic acid were, respectively, 79, 74, and 46 kJ mol(-1). Losses calculated during isothermal treatments were close to experimental losses in pheophytin a, hydroxypheophytin a', and ascorbic acid. The Eyring model can then be used to predict chlorophyll pigments and vitamin C losses during pasteurization of the nectar (<10%).  相似文献   

Capillary electrophoresis of free fatty acids by indirect ultraviolet detection: application to the classification of vegetable oils according to their botanical origin     

Vergara-Barberán M  Escrig-Doménech A  Lerma-García MJ  Simó-Alfonso EF  Herrero-Martínez JM 《Journal of agricultural and food chemistry》2011,59(20):10775-10780

A method for the determination of fatty acids in vegetable oils by capillary electrophoresis with indirect UV-vis detection has been developed. The separation of fatty acids was optimized in terms of Brij surfactant nature and concentration and organic modifier (2-propanol) percentage. The optimal background electrolyte consisted of 10 mM p-hydroxybenzoate, 5 mM Tris at pH 8.8, 80 mM Brij 98, 40% acetonitrile, and 10% 2-propanol. Under these conditions, vegetable oils from five botanical origins (avocado, corn, extra virgin olive, hazelnut, and soybean) were analyzed and the fatty acid contents established. Linear discriminant analysis (LDA) models were constructed using fatty acid peak areas as predictors. An excellent resolution among all category pairs was obtained, and all samples were correctly classified with assignment probabilities of >95%.  相似文献   

Foamability and foam stability of molecular reconstituted model sparkling wines     

Coelho E  Rocha SM  Coimbra MA 《Journal of agricultural and food chemistry》2011,59(16):8770-8778

The present work aims at identifying the contribution of the different wine components to the foaming properties of wines. Twelve fractions were isolated from wine, and foam aptitude of each fraction was measured individually at the concentration at which it was recovered, using wine model solutions. For these concentrations, the maximum foam height (HM) was 8.4-11.7 cm, foam height on stability was 6.9-7.5 cm, and foam stability (TS) was 3.0-6.5 s. Moreover, foam measurements were also performed using 2-, 5-, and 10-fold concentrations of these compounds in wine. The HM increased linearly with the concentration of mannoproteins having low content of protein (MP1), and TS increased exponentially. The fractions that individually showed higher foaming properties were mixed in binary and ternary combinations, demonstrating that MP1 when mixed with low molecular weight hydrophobic compounds strengthens the air/water interface of these solutions, a characteristic that is on the basis of sparkling wines' foamability and foam stability.  相似文献   

Solid phase microextraction of volatile emissions of Ceratitis capitata (Wiedemann) (Diptera: Tephritidae): influence of fly sex, age, and mating status     

Alfaro C  Vacas S  Zarzo M  Navarro-Llopis V  Primo J 《Journal of agricultural and food chemistry》2011,59(1):298-306

Considerable efforts have been devoted to understanding the courtship behavior and pheromone communication of medflies; however, the sex pheromone composition is still a controversial subject. The discovery of new components affecting medfly behavior would be of interest for medfly control methods based on semiochemicals. This work describes volatile compounds emitted by Ceratitis capitata collected using solid phase microextraction. The volatile study was conducted according to an experimental design with three factors (sex, age, and mating status) assumed to be relevant for better understanding the chemical communication. Emission data were treated by means of principal component analysis, a statistical methodology not previously applied to the study of volatiles emitted by fruit flies. The characterization of emission patterns could be useful for the selection of compounds to be further investigated in biological assays to improve knowledge of the key semiochemicals involved in medfly behavior.  相似文献   

Adsorption and desorption behavior of metalaxyl in intensively cultivated acid soils     

Bermudez-Couso A  Fernandez-Calvino D  Pateiro-Moure M  Garrido-Rodriguez B  Novoa-Munoz JC  Estevez MA 《Journal of agricultural and food chemistry》2011,59(13):7286-7293

Metalaxyl adsorption and desorption behavior in acid soils were evaluated via batch and stirred-flow chamber experiments. On the basis of batch experiments (adsorption curves of the Giles C-type), metalaxyl has a low affinity for acid soils. Also, as derived from batch and stirred-flow chamber tests, its adsorption in acid soils is dictated mainly by their organic matter and clay contents. The high correlation between these two variables makes it rather complicated to resolve their effects. Metalaxyl adsorption occurs largely (80-99%) via fast adsorption reactions. On the other hand, the pesticide is desorbed in variable proportions (30-100%). The desorption parameters obtained by fitting the results to a pseudo-first-order reaction were correlated with no edaphic variable; however, the q(0)/q(max) ratio, which is a measure of reversibility in the adsorption-desorption process, exhibited significant negative correlation with the organic matter and clay contents.  相似文献   

Comparison Between Industrial�CUrban and Rural Particle Stations in a Ceramic Cluster (NE, Spain)     

Ana Belen Vicente  Teofilo Sanfeliu  Manuel Miguel Jordan 《Water, air, and soil pollution》2011,215(1-4):83-96

Since the beginning of the twentieth century, the province of Castellón, in eastern Spain, has been one of the most important areas of floor and wall tile production on both a national and worldwide scale. As a result of this sector??s productive rate of development (in the 1970?C2005 interval), a series of pollution-producing chemical substances has been introduced into the atmosphere. The objective of this study is the comparison between industrial?Curban and rural zones in this province, with the goal of establishing the causes of the contamination in order to apply corrective measures upon the different emission sources. Sustainable development is sought after to guarantee that, in the future, the environmental quality parameters fall within legal limits, ensuring the population??s well-being as well as conserving natural ecosystems and material assets. Total suspended particles and PM10 are the parameters studied. The reason for choosing this pollutant type is because particulate matter may present a much higher potential risk despite its low representativeness as compared to the gas pollutant??s group. A positive correlation between high particle concentrations and deterioration in public health has been shown in recent studies. The elements As, Cd, Ni, and Pb in PM10 were also analyzed to determine the toxicity of these particles. This study has demonstrated the different behaviors of the parameters studied at different types of stations (industrial?Curban and rural), leading to the conclusion that anthropogenic factors are very important in the area studied and that they determine the area??s air quality to a great extent.  相似文献   

Healthy food availability and the association with BMI in Baltimore, Maryland     

Casagrande SS  Franco M  Gittelsohn J  Zonderman AB  Evans MK  Fanelli Kuczmarski M  Gary-Webb TL 《Public health nutrition》2011,14(6):1001-1007

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Gibberellic acid and flower bud development in loquat (Eriobotrya japonica Lindl.)     

Carmina Reig  Vittorio Farina  Giorgio Volpe  Carlos Mesejo  Amparo Martínez-Fuentes  Francesca Barone  Francesco Calabrese  Manuel Agustí 《Scientia Horticulturae》2011

The application of gibberellic acid (GA₃) to the whole loquat tree from mid-May to early June and from early August to the onset of flowering, significantly reduced the number of premature flowering shoots per current shoot and per m³ of canopy, and so reduced the total number of panicles per m³ of canopy. The number of vegetative shoots per m³ of canopy was also significantly reduced by applying GA₃. The response depended on the concentration applied and produced optimal results at 50 mg l⁻¹. Differences in the number of flowers per panicle and leaves per shoot were not significantly modified by the treatment. Nevertheless, GA₃ applied directly to the developing apex near to flower differentiation reduced the number of flowers per panicle by 25–35% and without modifying the morphological characteristics of the panicle. Results suggest that less sprouting of lateral buds was largely responsible for the reduction in flowering intensity caused by GA₃. Best treatments reduced thinning costs (60%, approximately) of premature flowering shoots, slightly increased fruit diameter and significantly improved fruit colour and juice quality, thus advancing harvest date.  相似文献