Polyphenol content and antioxidative activity in some species of freshly consumed salads

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.     

Structure-activity relationship development of dihaloaryl triazole compounds as insecticides and acaricides. 1. Phenyl thiophen-2-yl triazoles

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.     

Different mycorrhizal fungal strains determine plant community response to nitrogen and water availability

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.     

The HEALTHGRAIN Cereal Diversity Screen: concept, results, and prospects

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.     

Dietary combination of conjugated linoleic acid (CLA) and pine nut oil prevents CLA-induced fatty liver in mice

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.     

Influence of drip and furrow irrigation systems on nitrogen oxide emissions from a horticultural crop

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.     

Predicting perchlorate exposure in milk from concentrations in dairy feed

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.     

Soil carbon dioxide (CO2) fluxes in permanent upslope pasture and downslope riparian buffers with varying vegetation

Background

Riparian buffers are primarily implemented for their water quality functions in agroecosystems. Their location in the agricultural landscape allows them to intercept and process pollutants from immediately adjacent agricultural land. Vegetated riparian buffers recycle soil organic matter, which elevates soil carbon (C), which upon processing, processes and releases carbon dioxide (CO₂). The elevated soil C and seasonally anoxic environments associated with riparian buffers promote denitrification and fermentation, further increasing soil CO₂ production.

Aim

Against this context, a replicated plot-scale experiment was established at North Wyke, UK, to measure the extent of soil CO₂ emissions in permanent pasture served by grass, willow, and woodland riparian buffers, as well as a no-buffer control.

Methods

Soil CO₂ was measured using the static chamber technique in conjunction with soil and environmental variables between June 2018 and February 2019.

Results

Cumulative soil CO₂ fluxes were in the descending order: woodland riparian buffer; 11,927.8 ± 1987.9 kg CO₂ ha^–1 > no-buffer control; 11,101.3 ± 3700.4 kg CO₂ ha^–1 > grass riparian buffer; 10,826.4 ± 2551.8 kg CO₂ ha^–1 > upslope pasture; 10,554.6 ± 879.5 kg CO₂ ha^–1 > willow riparian buffer; 9294.9 ± 1549.2 5 kg CO₂ ha^–1. There was, however, no evidence of significant differences among all treatments of the current study.

Conclusions

Despite the lack of significant differences, the results from our short-term study show that the woodland riparian buffer had relatively larger soil CO₂ emissions than the remainder of the other riparian buffers and the upslope pasture it serves. Our short-term findings may be useful in developing soil CO₂ mitigation strategies through careful selection of riparian buffer vegetation and may be useful in calibrating mechanistic models for simulating such emissions from similar agro systems.     

Cover crop identity determines root fungal community and arbuscular mycorrhiza colonization in following main crops

Cover crops (CC) can promote nutrient retention and recycling for main crops yet may also promote soilborne pathogens or suppress beneficial root symbionts such as arbuscular mycorrhizal fungi (AMF). We investigated how root fungal communities of main crop are affected by preceding CC monocultures and mixtures and by main crop identity. We expected that AMF abundance and diversity in main crops are promoted by AM-host CC, and suppressed by non-AM-host CC, and that mixtures of CC species can promote beneficial and suppress pathogenic root fungi. Our full-factorial field experiment comprised crop rotation in sand soil with different CC treatments (monocultures of radish [AM non-host], ryegrass, clover, vetch [AM hosts], mixtures of radish + vetch, ryegrass + clover and fallow) and two main crops (oat and endive). At peak crop growth, we investigated the root fungal communities in the main crops using microscopy and high throughput sequencing (Illumina MiSeq). Cover crop identity was of prime importance and CC legacy overruled main crop identity in determining root fungal communities in main crops. Compared with fallow, CC with ryegrass increased AMF colonization and richness in both main crops and of non-AMF in oat. Legacies of ryegrass, ryegrass + clover and vetch resulted in distinct root fungal communities in the main crops, while the legacy of CC with radish were similar to the legacy of fallow. Root fungal community in crops after clover had highest abundance of representative fungal pathogens in contrast with the other CC treatments that resulted in fungal communities where pathogens were scarce. Oppositely to expected, CC mixtures did not enhance fungal symbionts or suppressed pathogens. Overall, fungal communities in roots of the main crops in our field experiment were determined by the preceding CC species in monoculture, rather than by the CC AMF preference or functional group. This research highlights that the choice of CC determines the root fungal community in main crop which may influence crop quality.