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991.
Event-based precipitation samples were collected during the main agricultural season (April-September) over 4 years (2000-2003) at one site in the Choptank River Watershed on the Delmarva Peninsula. The samples were analyzed for 19 agricultural pesticides to determine the contribution of wet deposition as a source of these compounds to the Chesapeake Bay and the factors affecting the temporal trends in deposition. Chlorothalonil was detected most frequently (92% samples) followed by metolachlor (66%) and endosulfans (49%). Although chlorothalonil is the single biggest contributor to pesticide flux (33-46%), pesticide wet deposition is dominated by herbicides (46-61%), with the greatest fluxes occurring during the time of herbicide application on corn and soybeans. The analysis suggests that the extent of wet deposition of herbicides depends on the timing of precipitation relative to herbicide application. The insecticide and fungicide flux was greater in years with above-average rainfall (2001 and 2003), suggesting that for these pesticides deposition flux is dependent on the total amount of rainfall in the agricultural season. The data indicate that the use of chlorpyrifos, an organophosphate insecticide which is on the Toxics of Concern list for the Bay, is on the increase. Total pesticide flux ranged from 90 microg/m2 (2001) to 180 microg/m2 (2000). Wet deposition can account for up to 10-20% of the annual loadings of pesticides to the Bay. 相似文献
992.
Coppola L Castillo Md Monaci E Vischetti C 《Journal of agricultural and food chemistry》2007,55(2):396-401
Biobeds developed in Sweden bind and degrade pesticides from point sources. The objective of this work was to adapt the biobed to Italian operating conditions, for example, to identify organic materials as effective as those in the original Swedish composition. The capacity of urban and garden composts alone or mixed with citrus peel or straw to degrade chlorpyrifos and its metabolite TCP was compared to the typical Swedish biomix consisting of straw, peat, and soil. A tendency for higher 14C-chlorpyrifos mineralization and lower TCP levels was observed in the biomixes with garden compost alone or amended with straw. In a second trial, a high correlation of lower TCP with increasing levels of straw in typical Swedish biomixes was observed. Straw stimulates production of lignin-degrading enzymes such as manganese peroxidase (MnP), and further trials with pure MnP showed that this enzyme degrades TCP. Materials with an active lignin-degrading microflora are a prerequisite for effective dissipation of chlorpyrifos and non-accumulation of TCP. Thus, lignocellulosic materials as straw and garden composts should be present in biomixes to be used under Italian conditions. 相似文献
993.
Heimler D Isolani L Vignolini P Tombelli S Romani A 《Journal of agricultural and food chemistry》2007,55(5):1724-1729
Ten genotypes belonging to Lactuca sativa, Cicorium intybus, Plantago coronopus, Eruca sativa, and Diplotaxis tenuifolia and used in fresh mixed salads were investigated for their polyphenol contents. Flavonoids and hydroxycinnamic acids were characterized by high-performance liquid chromatography (HPLC)/diode array detection/mass spectrometry. Quercetin, kaempferol, luteolin, apigenin, and crysoeriol derivatives were identified; hydroxycinnamic acids were all caffeoyl derivatives. The total polyphenol content was obtained through the Folin-Ciocalteu test and from the HPLC data. The amounts ranged between 0.9 and 4.7 mg/g fresh weight. The antiradical activity was determined by the reaction with the stable DPPH* radical. The Fe2+ chelating activity was determined with a spectrophotometric test. From the complex of data, a quite complete picture of the characteristics of the vegetables emerges. A cultivated C. intybus cultivar exhibited the highest polyphenol content, while a wild C. intybus genotype exhibited the highest antiradical activity. In every case, the characteristics of the different salads as functional foods have been pointed out. 相似文献
994.
Cudworth DP Hegde VB Yap MC Guenthenspberger KA Hamilton CT Pechacek JT Johnson PL Bis SJ Tisdell FE Dripps JE Bruce TJ Dintenfass LP Gifford JM Karr LL Kempe MK McCormick DC Schoonover JR 《Journal of agricultural and food chemistry》2007,55(18):7517-7526
An extended lipophilic system that incorporated some key elements of first-generation 2,6-dihaloaryl actives, such as 1, demonstrated desirable efficacy against chewing insects as well as sap-feeding insects. These four-ring systems, based on 2, were accessed primarily via Suzuki couplings of halothiophene derivatives with appropriately substituted boronic acids. In particular, phenylthiophene systems that incorporated haloxyether groups, such as those in 3, 4, and 5, had the broadest spectrum of activity across chewing and sap-feeding insect pests. Expansion of this structure-activity relationship to include compounds with differing substitution patterns on the thiophene-C-ring and aryl-D-rings was undertaken. The synthesis and insecticidal activity of 3-aryl-5-(thiophen-2-yl)-1-methyl-1H-[1,2,4]triazoles will be described. 相似文献
995.
Different mycorrhizal fungal strains determine plant community response to nitrogen and water availability 下载免费PDF全文
Laura B. Martínez‐García Raúl Ochoa‐Hueso Esteban Manrique Francisco I. Pugnaire 《植物养料与土壤学杂志》2015,178(1):146-154
Most research on the mycorrhizal positive–negative responsiveness continuum (or “mutualism–parasitism continuum”) has focused on individual plant species growing at different levels of P availability. Here, we explore this continuum in an experimental plant community inoculated with three arbuscular mycorrhizal (AM) fungal strains (both single and mixed) growing under four resource availability scenarios. These scenarios are a factorial combination of two levels of water and N availability. Each AM fungal strain had a different origin: an arid ecosystem, a farmland, and a mine. We hypothesized that the response of the plant community to mycorrhizal inoculum would depend on the associated AM fungal strain and would be negatively related with increased nitrogen and water availability. Our results showed that mixed‐strain AM fungal inoculation had more positive effects along a wider range of water and N availability scenarios than single‐strain inoculation. In contrast, mycorrhizal growth response of plants inoculated with a single AM fungal strain shifted from positive to neutral and negative depending on resource availability. Adaptation of each strain to its local conditions might confer different properties to the mycorrhizal symbiosis. Therefore, we conclude that AM fungal origin and environmental limiting resources are crucial factors to predict plant community mycorrhizal growth response in changing ecosystems. 相似文献
996.
997.
Ward JL Poutanen K Gebruers K Piironen V Lampi AM Nyström L Andersson AA Aman P Boros D Rakszegi M Bedo Z Shewry PR 《Journal of agricultural and food chemistry》2008,56(21):9699-9709
One hundred and fifty bread wheat lines and 50 other lines of small-grain cereals (spelt, durum wheat, Triticum monococcum, Triticum dicoccum, oats, rye, and barley) were selected for diversity in their geographical origin, age, and characteristics. They were grown on a single site in Hungary in 2004-2005, harvested, milled, and analyzed for a range of phytochemicals (tocols, sterols, phenolic acids, folates, alkylresorcinols) and fiber components that are considered to have health benefits. Detailed analyses of these components in the different species are reported in a series of accompanying papers. The present paper discusses the comparative levels of the bioactive components in the different species, showing differences in both ranges and mean amounts. Furthermore, detailed comparisons of the bread wheat lines show that it is possible to identify lines in which high levels of phytochemicals and dietary fiber components are combined with good yield and processing quality. This means that commercially competitive lines with high levels of bioactive components are a realistic goal for plant breeders. 相似文献
998.
Ferramosca A Savy V Conte L Zara V 《Journal of agricultural and food chemistry》2008,56(17):8148-8158
Conjugated linoleic acid (CLA) strongly prevents fat accumulation in adipose tissue of mice, even if hepatic fat deposition and insulin resistance are concomitantly observed. This study investigated the possibility of maintaining the antiadiposity properties of CLA while preventing adverse effects such as liver steatosis and hyperinsulinemia. To this end, mice were divided into three groups and fed a standard diet (control) or a diet supplemented with 1% CLA (CLA) or a mixture of 1% CLA plus 7.5% pine nut oil (CLA + P). The combination of CLA + P preserved the CLA-mediated antiadiposity properties (70% fat reduction), preventing hepatic steatosis and a sharp increase in plasmatic insulin starting from the eighth week of CLA treatment. The assay of both fatty acid synthesis and oxidation in the CLA + P mice revealed a time-dependent biphasic behavior of the corresponding enzymatic activities. A sudden change in these metabolic events was indeed found at the eighth week. A strong correlation between the changes in key enzymes of lipid metabolism and in insulin levels apparently exists in CLA-fed mice. Furthermore, lower levels of lipids, in comparison to values found in CLA-fed mice, were observed in the liver and plasma of CLA + P-fed animals. 相似文献
999.
Laura Sánchez-Martín Augusto Arce Alejandro Benito Lourdes Garcia-Torres Antonio Vallejo 《Soil biology & biochemistry》2008,40(7):1698-1706
Irrigation management has an important influence on emissions of nitrous oxide (N2O) and nitric oxide (NO) from irrigated agricultural soils. In order to develop strategies to reduce the emission of these gases, a field experiment was carried out to compare the influence of different irrigation systems: furrow (FI) and drip-irrigation (DI), on N2O and NO emissions from a soil during the melon crop season. Two fertilizer treatments were evaluated for each irrigation regime: ammonium sulphate (AS) as a mineral N fertilizer, at a rate of 175 kg N ha?1; and a control without any N fertilizer (Control). On plots where the AS treatment was applied, drip irrigation reduced total N2O and NO emissions (by 70% and 33% respectively) with respect to values for furrow irrigation. This was probably due to the lower amount of water applied and the different soil wetting pattern associated with DI. Dry areas of the drip-irrigated plots emitted a similar amount of N2O to the wet areas (0.45 kg N2O-N ha?1) in the Control and greater quantities in the AS treatment (0.92 kg N2O-N ha?1 for dry and 0.70 kg N2O-N ha?1 for wet areas). We suggest that the N oxide pulses observed throughout the irrigation period on DI plots could have been the result of frequent increases in the soil wetting volume after the addition of water. Denitrification losses (from depths of 0–10 cm) were estimated at 11.44 kg N2O- N ha?1 for the AS treatment under FI and at 4.96 kg N2O-N ha?1 for DI. Under DI, nitrification was an important source of N2O, whereas denitrification was the most important source under FI. The addition of NH4+ and the use of DI enhanced the N2O/N2 ratio of gases produced through denitrification. The quantity of dissolved organic C (DOC) in the soil generally decreased with addition of NH4+.This work showed that, in comparison with furrow irrigation, drip irrigation is a method that can be used to save water and mitigate emissions of the atmospheric pollutants NO and N2O. 相似文献
1000.
Rice CP Baldwin Vi RL Abbott LC Hapeman CJ Capuco AV Le A Bialek-Kalinski K Bannerman DD Hare WR Paape MJ McCarty GW Kauf AC Sadeghi AM Starr JL McConnell LL Van Tassell CP 《Journal of agricultural and food chemistry》2007,55(21):8806-8813
Perchlorate has been detected in U.S. milk samples from many different states. Applying data from a recently reported 9-week experiment in which 16 Holstein dairy cows were administered perchlorate allowed us to derive an equation for the dose-response relationship between perchlorate concentrations in feed/drinking water and its appearance in milk. Examination of background concentrations of perchlorate in the total mixed ration (TMR) fed in addition to the variable dose supplied to treated cows as a ruminal infusate revealed that cows receive significant and variable exposure to perchlorate from the TMR. Weekly examination of the TMR disclosed that a change in ingredients midway through the experiment caused a significant (78%) change in TMR perchlorate concentration. Analyses of the ingredients comprising the TMR revealed that 41.9% of the perchlorate came from corn silage, 22.9% came from alfalfa hay and 11.7% was supplied by sudan grass. Finally, USDA Food and Nutrition Survey data on fluid milk consumption were used to predict potential human exposure from milk that contained concentrations of perchlorate observed in our previous dosing study. The study suggests that reducing perchlorate concentration in dairy feed may reduce perchlorate concentrations in milk as well as the potential to reduce human exposure to perchlorate in milk. 相似文献