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Greenhouse vegetable production is often associated with the excessive use of nitrogen fertilizers and a high rate of nitrate accumulation. We evaluated the uptake, translocation, and accumulation of nitrate in chard and spinach under greenhouse conditions with optimal fertilization. The results revealed low levels of nitrate in the leachates and substrates (chard ˃ spinach). The high nitrate concentrations in the root zone of spinach compared to those of chard were correlated with a high rate of accumulation in the stem, aerial fraction, and leaves (p < 0.0001). The nitrate concentration in spinach exceeded the limit established by international regulations by 3-fold. The daily intake of nitrate exceeded the acceptable daily intake (ADI) value in almost all age groups (except 13–19 years). However, in the age group of 1–2 years, the daily intake value (7.87 mg NO 3 − kg−1) was two times higher than the ADI. To improve the quality of food for children, food contamination monitoring programs must ensure adherence to production standards. [Display omitted] • The dynamics of nitrate in greenhouse systems were studied. • Nitrogen fertilization facilitates accumulation of nitrate in plant tissues. • The accumulation rate in both species was: leaves > aerial parts > stem. • Spinach accumulates more nitrate than chard, at levels that exceed international regulations. [ABSTRACT FROM AUTHOR]

Objective We compared three methods for estimating the individual peak height velocity (PHV) and age at peak height velocity (APHV) from the SuperImposition by Translation and Rotation (SITAR) model. Methods We fitted the SITAR model using simulated data and heights of 12 girls from the Chard Growth Study and obtained individual PHVs and APHVs from three methods: the model method, the quadratic function method and the numerical method, which are available in our newly developed R package“iapvbs”. The mean, interquartile range, range of biases in estimated APHV and PHV as well as the rates of warning and unreasonable cases, i.e. estimated APHVs being outside the range of age measurements, from the three methods were presented and compared. Results When the growth curves of all individuals were well fitted by the SITAR model, all three methods estimated individual APHVs with similarly small biases, with a few unreasonable cases (0.16%) observed when the model method was used while more computation time required for the numerical method. When the growth curves of some individuals were not very well fitted, the model method generated more unreasonable individual APHV (8.15%) and more bias in PHV and APHV, compared to those estimated by the numerical method and quadratic function method. In line with the observations from the simulated data, the real data analysis demonstrated that the numerical method generated more reliable PHV and APHV for individuals with growth curve not well fitted by the SITAR model. Conclusion The performance of different methods estimating individual APHV depends largely on how well the growth curves are fitted by the SITAR model. The quadratic function method is more superior when growth curves of all individuals are well fitted by the SITAR model; otherwise, the numerical method should be adopted for getting most robust estimates of PHV and APHV. The model method generates unreasonable APHV estimates, particularly when the growth curves are not well fitted. [ABSTRACT FROM AUTHOR]

The influence of organic nitrogen sources on the establishment of E. coli O157:H7 and the occurrence of other potentially human pathogenic bacteria on baby leaf salads was evaluated. Greenhouse-grown rocket and Swiss chard were spray-inoculated with gfp -tagged E. coli O157:H7 twice a week from when their first true leaves reached a length of 2 cm until three days before harvest. Analysis of nitrogen content in leaves revealed differences between treatments. Untreated plants had the lowest values, followed by plants fertilized with pig hair pellets and chicken manure. The same pattern was seen for the growth medium at the day of harvest. The applied strain showed similar establishment (measured using culture-dependent methods) irrespective of treatment, but Swiss chard hosted significantly more E. coli O157:H7 than rocket. Differences in the risk of infection were found for the crops, with plants fertilized with pig hair pellets showing a slightly higher risk. No relationship was found for total nitrogen content in leaves and colonization with E. coli O157:H7 gfp +. Isolating dominant Enterobacteriaceae from leaves, some strains showed conformity to bacterial species that have previously been identified to influence the establishment of E. coli O157:H7 in the phyllosphere. In this study, no inhibitory effects were observed in vitro . Colonies showing matching characteristics for Listeria spp. and Salmonella spp. were detected up to 5.5 and 5 log CFU g −1 fresh weight, respectively. However, presumptive Listeria spp. and Salmonella spp. could not be confirmed by sequencing of the 16S rRNA gene. [ABSTRACT FROM AUTHOR]

Cercospora leaf spot caused by Cercospora beticola is a significant threat to the production of sugar and table beet worldwide. A de novo genome assembly of C. beticola was used to develop eight polymorphic and reproducible microsatellite markers for population genetic analyses. These markers were used, along with five previously described microsatellite loci to genotype two C. beticola populations from table beet fields in New York, USA. High allelic and genotypic diversity and low population differentiation were found between fields. Linkage disequilibrium of loci after clone-correction of datasets was attributed to the presence of two distinct clonal lineages within the populations. Linkage equilibrium of loci in one of the clusters supported the presence of sexual reproduction. The draft de novo genome assembly will help elucidate the reproductive system of C. beticola through investigating evidence of recombination in the C. beticola genome. [ABSTRACT FROM AUTHOR]

Timely information on crop foliar nutrient content provides a measure of crop nutritional and vitality status. Growers and farm managers use such information for precision crop management such as an appropriate fertilizer application to correct for any crop nutrient deficiencies at identified hotspots. Foliar heavy nutrient content could also be a direct indicator of crops having been polluted from the surroundings, which may be a result of heavy metals absorbed from, among others, contaminated soils and waste water. In the present study, we explored the potential use of four partial least squares (PLS)-based regression algorithms for estimating foliar Swiss chard macro- and micronutrient concentrations using ground-based hyperspectral data under three treatments; i.e. rainwater + fertilizer (‘R + F’), tap water + fertilizer (‘T + F’), and treated wastewater (‘W’). Swiss chard canopy-level hyperspectral measurements under these three treatments were collected using a handheld spectroradiometer 2.5 months after sowing. The reflectance spectra were normalized to their first-order derivatives. The concentrations of three Swiss chard foliar macronutrients (NPK) and three micronutrients (Zn, Cu and Fe) under the three treatments were determined. Regression models for estimating macro- and micronutrient concentrations were then derived using PLS1 and sparse PLS1 methods, while the potential simultaneous estimation of the macronutrient as well as micronutrient concentrations was explored using the PLS2 and SPLS2 regression approaches. Results showed that high variances in the macro- and micronutrient concentrations can be explained by the four regression models under the three treatments ( R 2 train ranged between 0.73 and 0.99), except when P, Zn and Cu concentrations were estimated using the PLS2-based models under the three treatments ( R 2 train ranged between 0.08 and 0.68) and Fe concentration using SPLSR1 under ‘W’ treatment ( R 2 train = 0.64). Our results further showed that Swiss chard foliar N (RMSE = 1.67%) concentration under ‘R + F’ treatment and Fe (RMSE = 7.83%) concentration under the ‘T + F’ treatment most accurately estimated macro- and micronutrients. Our study also showed that the Swiss chard foliar macronutrient concentrations were more accurately estimated compared to micronutrient concentrations and PLS2 outperformed the PLS1 based regression model. The results of the current study pave the way for developing an effective foliar nutrient estimation routine suitable for monitoring Swiss chard nutrient status under different treatments. [ABSTRACT FROM AUTHOR]

Two open-top chamber experiments were carried out at a continental and a coastal location in Spain to test the ozone sensitivity of spinach ( Spinacia oleracea L.) and Swiss chard ( Beta vulgaris L. var. cycla ) under Mediterranean conditions. Three cultivars of spinach and two cultivars of Swiss chard currently grown in commercial fields were screened for ozone tolerance in terms of marketable yield. Different physiological parameters were measured to identify traits related with this tolerance and ozone effects on yield quality. All the spinach and Swiss chard cultivars tested in this study were sensitive to ozone in terms of marketable biomass yield. The commercial biomass decreased on average between 13.8 and 17.9% in spinach and between 0 and 20.1% in Swiss chard at a continental and a coastal site, respectively, after two months of ozone exposure under ambient plus 40 ppb of ozone concentration compared to charcoal-filtered air. Ozone effects on the marketable yield were associated with the appearance of leaf visible injury and by reductions in the photosynthetic activity of the leaves. Swiss chard cultivars were generally more ozone tolerant than spinach cultivars. However, the ozone sensitivity differed between cultivars of the same species and effects were more pronounced at the coastal site, where environmental growing conditions favoured plant growth more than at the continental site. The physiological traits analysed (photosynthesis and gas exchange parameters and ascorbate concentration and redox status) were not related to differences in ozone tolerance between cultivars. Ozone effects on leaf nitrogen content and greenness reflected the impact of ozone on yield quality parameters for leafy vegetables, such as leaf nitrate concentration and the marketable value. These results show that leafy vegetables can be more sensitive to ozone than other horticultural crops like tomato, which is used as a representative crop in risk assessments of ozone effects on horticultural production in Europe. [ABSTRACT FROM AUTHOR]

Swiss chard ( Beta vulgaris subsp. cicla) shoots contain high amounts of carotenoid and chlorophyll pigments and can be enhanced through varying cultural management practices, such as temperature, light, and mineral nutrient levels. The purpose of this study was to determine the effects of nitrogen (N) form and ratio on the carotenoid and chlorophylls concentrations in Swiss chard leaf tissue. Seeds of ‘Rhubarb Chard’ and ‘Oriole Orange’ Swiss chard were germinated under greenhouse conditions at the University of Tennessee (UT) and Mississippi State University (MSU). Plants were grown at 25/20 °C (day/night) and grown hydroponically in different N forms and ratios given as ammonium and nitrate N. Plants were analyzed for biomass production, carotenoid and chlorophyll concentrations, and xanthophyll pigment ratios in the shoot tissue. Swiss chard biomass accumulation responded significantly to N form ( P ≤ 0.001), and the interaction of N form and location ( P ≤ 0.01). Carotenoid and chlorophyll concentrations were also significantly affected by N form ( P ≤ 0.001), and the interaction of N form and location ( P ≤ 0.01). Specifically, concentrations of lutein (LUT), β-carotene (BC), neoxanthin (NEO), violaxanthin (VIO), and antheraxanthin (ANTH) increased by 42.0%, 45.1%, 49.0%, 59.3%, and 36.0%, respectively, when decreasing the treatment ratio of NH 4 -N:NO 3 -N from 100:0 to 25:75. Similarly, chlorophyll a (Chl a ) and chlorophyll b (Chl b ) increased 44.9% and 40.9%, respectively. There were significant differences in xanthophyll cycle pigments between the two locations. Higher light intensities at the MSU location may have contributed to lower pigment concentrations in the shoot tissues of Swiss chard. Since N fertility is important to overall health of the plant, it is crucial to understand the influence of managing it in a production system aimed to increase yields and nutritionally important pigmentation in Swiss chard. Thus, the recommendation for increase biomass accumulation and health promoting carotenoid and chlorophyll concentrations in the leaf tissue should consider decreasing NH 4 -NO 3 ratios in a fertility program to 25% NH 4 -N:75% NO 3 -N. [ABSTRACT FROM AUTHOR]

A simultaneous method was developed to analyse thiamethoxam and its metabolite clothianidin in Swiss chard using tandem mass spectrometry (in the positive electrospray ionisation mode using multiple reaction monitoring mode) to estimate the dissipation pattern and the pre-harvest residue limit (PHRL). Thiamethoxam (10%, WG) was sprayed on Swiss chard grown in two different areas under greenhouse conditions at the recommended dose rate of 10 g/20 L water. Samples were collected randomly up to 14 days post-application, extracted using quick, easy, cheap, effective, rugged, safe (QuEChERS) acetate-buffered method and purified via a dispersive solid phase extraction (d-SPE) procedure. Matrix matched calibration showed good linearity with determination coefficients ( R 2 ) ⩾ 0.998. The limits of detection (LOD) and quantification (LOQ) were 0.007 and 0.02 mg/kg. The method was validated in triplicate at two different spiked concentration levels. Good recoveries ( n = 3) of 87.48–105.61% with relative standard deviations (RSDs) < 10 were obtained for both analytes. The rate of disappearance of total thiamethoxam residues in/on Swiss chard was best described by first-order kinetics with half-lives of 6.3 and 4.2 days. We predicted from the PHRL curves that if the residues were <19.21 or 26.98 mg/kg at 10 days before harvest, then total thiamethoxam concentrations would be below the maximum residue limits during harvest. [ABSTRACT FROM AUTHOR]

Salinity is known to reduce NO 3 − uptake in many plants. Our previous study found that the increasing NaCl concentrations in media enhanced NO 3 − uptake in leaves. Here, we investigated whether nitrate ( NO 3 − ) uptake by Swiss chard ( Beta vulgaris var. cicla L.) was affected more by Na + than by K + , and elucidated which NO 3 − uptake processes were related to the application of these ions in the culture medium. Plants were grown hydroponically and subjected to 5 mM or 50 mM of either K or Na treatments for 7 days: K5 (K 5, Na 0), K50 (K 50, Na 0), Na5 (K 0, Na 5), and Na50 (K 0, Na 50). The leaf NO 3 − concentration was significantly enhanced in the Na treatments compared with the K treatments. The ratio of leaf to root NO 3 − concentrations in K5 and Na5 were 0.46 and 1.59, respectively, which indicates that NO 3 − is translocated to the leaves in the Na treatments. The NO 3 − concentration in the xylem sap, collected 6 h after the start of the treatments, was significantly higher in Na50 than in the other treatments. These are the opposite of the results for Arabidopsis , which accumulates NO 3 − in its roots to increase its salinity tolerance. Our results suggest that Na but not K enhances NO 3 − uptake and transport to the leaves in Swiss chard and that its function may relate to xylem translocation of NO 3 − . [ABSTRACT FROM AUTHOR]

In the current study, the effect of dill, parsley, spinach, and Swiss chard powder on the physicochemical, microbial, textural, and sensory properties of sucuk production during the seven-day ripening period was investigated. Six different fermented sucuks were produced, C1: 100 mg/kg sodium nitrite; C2: 100 mg/kg sodium nitrate; T1: dill powder 0.71%; T2: parsley powder 1.17%; T3: spinach powder 0.29% and T4: Swiss chard powder 0.26%. In group T4, a higher titratable acidity and lower pH values were found compared to the other groups (P < 0.01). No residual nitrate was detected in groups T3 and T4 at the end of the ripening period. Swiss chard powder (T4) increased the redness of the sucuks (P < 0.01). Naturally cured sucuks had higher lactic acid bacteria (LAB) counts than the control groups (P < 0.01). The T3 and T4 groups had the highest scores of flavour and overall acceptance (P < 0.05). Therefore, spinach and Swiss chard powder could be considered as a successful approach to produce naturally cured Turkish sucuk under the clean label concept. • Spinach and Swiss chard powders could be used as a natural curing agent in sausages. • Fermented sausages cured with vegetable powders had higher LAB counts. • Spinach and Swiss chard powder improved the sensory properties of Turkish sucuks. [ABSTRACT FROM AUTHOR]

Ingestion is one of the most important pathways to consider for calculating tritium dose to human beings. The objective of this study is to determine changes to TFWT and OBT concentrations in food as a result of its preparation for consumption. The contribution of OBT to the total tritium dose can be reduced by the oxidation of OBT during food preparation. The results show that preparation for consumption can result in reductions of up to 46% in TFWT concentration and 54% in OBT concentration in potato, and 22% in TFWT concentration and 57% in OBT concentration in Swiss chard. [ABSTRACT FROM AUTHOR]

There is an increasing demand for fresh vegetables such as Swiss chard in cognisance of their nutritive value. Early prediction of Swiss chard yield provides a valuable knowledge base for product management decisions like pre-harvest planning, post-harvest handing, food policy, and marketing. Consequently, the objective of the present study was to investigate the use of hyperspectral data in predicting yield of Swiss chard grown under different irrigation water sources. Swiss chard ground-based hyperspectral data were collected at canopy level using a handheld spectroradiometer at 2 and 2.5months after planting. Reflectance spectra were transformed to their first-order derivative and partial least squares (PLS) and sparse PLS (SPLS) regressions (R) were used for data analysis. Results showed that 95% and 97% of Swiss chard fresh and dry yields variation, respectively could be explained. SPLSR outperformed PLSR models for predicting Swiss chard fresh and dry yields. Results further showed that models developed using data collected when the crop was 2.5months old were more accurate than models derived using a 2-month old crop data, except the SPLSR model for predicting dry yield. Fresh yield estimates could be accurately modelled (root mean square error: RMSE=23.97% of the mean, Nash-Sutcliffe efficiency: NSE=0.93). However, Swiss chard dry yield could not be reliably predicted (at minimum RMSE=35.00% of the mean and a maximum NSE of 0.60 were obtained). This study demonstrates the potential of hyperspectral data in predicting Swiss chard fresh yield using combined irrigation treatments data sets. The study offers insight to the potential of large-scale prediction and estimation of Swiss chard yield using space borne and/or airborne hyperspectral data. [ABSTRACT FROM AUTHOR]

The transfer of Listeria monocytogenes to previously uncontaminated product during mechanical dicing of celery and its growth during storage at various temperatures were evaluated. In each of three trials, 275 g of retail celery stalks was immersed in an aqueous five-strain L. monocytogenes cocktail to obtain an average of 5.6 log CFU/g and then was diced using a hand-operated dicer, followed by sequential dicing of 15 identical 250-g batches of uninoculated celery using the same dicer. Each batch of diced celery was examined for numbers of Listeria initially and after 3 and 7 days of storage at 4, 7, and 10°C. Additionally, the percentage by weight of inoculated product transferred to each of 15 batches of uninoculated celery was determined using inoculated red stems of Swiss chard as a surrogate. Listeria transfer to diced celery was also assessed after removing the Swiss chard. L. monocytogenes transferred from the initial batch of inoculated celery to all 15 batches of uninoculated celery during dicing, with populations decreasing from 5.2 to 2.0 log CFU/g on the day of processing. At 10°C, Listeria reached an average population of 3.4 log CFU/g in all batches of uninoculated celery. Fewer batches of celery showed significant growth during storage at 4 and 7°C (P < 0.05). Swiss chard pieces were recovered from all 15 batches of celery, with similar amounts seen in batches 2 to 15 (P > 0.05). L. monocytogenes was also recovered from each batch of uninoculated celery after the removal of Swiss chard, with populations decreasing from 4.7 to 1.7 log CFU/g. Storing the diced celery at 10°C yielded a L. monocytogenes generation time of 0.87 days, with no significant growth observed during storage at 4 or 7°C. Consequently, mitigation strategies during dicing and proper refrigeration are essential to minimizing potential health risks associated with diced celery. [ABSTRACT FROM AUTHOR]

Statements that naturally cured meat products may contain lower residual nitrite levels compared to classical variants led to a closer examination of emulsion-type sausage products in this study, where the input of nitrate from plant extracts (red beet and Swiss chard) was adjusted to typical input levels of nitrite from nitrite curing salt (0.5% NaNO 2). The investigations showed that an incubation period of 150 min at 38 °C was necessary to complete the microbial reduction process of nitrate to nitrite and that residual nitrite contents of naturally cured sausages were comparable to the conventionally cured variant, regardless of the nitrate source. During the incubation period, the starter cultures were the dominant microorganisms and showed competitive properties against the natural accompanying flora. In terms of colour development, the variants with Swiss chard juice extract as well as synthetic nitrate showed similar colour formation to conventionally produced emulsion-type sausages. In contrast, colour-providing components of the red beet extract considerably masked the typical appearance. [ABSTRACT FROM AUTHOR]

Abstract: Chard is a plant used as an alternative hypoglycemic agent by diabetic people in Turkey. The aim of this study was to examine the molecular mechanism of hypoglycemic effects of chard extract. Male Sprague-Dawley rats (6–7 months old) were divided into five groups for this investigation: (1) control, (2) hyperglycemic, (3) hyperglycemic+chard, (4) hyperglycemic+insulin, (5) hyperglycemic+chard+insulin. Fourteen days after animals were rendered hyperglycemic by intraperitoneal injection of 60mg/kg streptozotocin, the chard water extract (2g/kg/day) or/and insulin (6U/kg/day) was administered for 45 days. Hypoglycemic effect of chard extract was demonstrated by a significant reduction in the fasting blood glucose and increased glycogen levels in liver of chard extract-treated hyperglycemic rats. Moreover, activity of adenosine deaminase, which is suggested as an important enzyme for modulating the bioactivity of insulin, was decreased by chard treatment. Immunostaining analysis showed increased nuclear translocation of Akt2 and synthesis of GLUT2 in the hepatocytes of chard or/and insulin-treated hyperglycemic rats. The oxidative stress was decreased and antioxidant defense was increased by chard extract or/and insulin treatment to hyperglycemic rats according to the decreased malondialdehyde formation, the activities of catalase, superoxide dismutase, myeloperoxidase and increased glutathione levels. These findings suggest that chard extract might improve glucose response by increasing GLUT2 through Akt2 and antioxidant defense in the liver. [Copyright &y& Elsevier]

Abstract: We report purification and characterisation of a polyphenol oxidase from red Swiss chard (rcPPO). Our purification procedure resulted in a 39-fold enrichment in specific activity and 17% recovery of total enzyme activity. The purified rcPPO appeared as a monomeric protein of 41kDa, with a specific conformation conserved in the Cu2+ combining region. It was optimally active at pH 7.5 and 45°C. It had a diphenolase substrate preference towards l-DOPA, catechol and chlorogenic acid, but also exhibited weak monophenolase one toward 4-methoxyphenol and l-tyrosine. We also found that the enzyme was activated by K+, Na+, SDS and laurouyl sarcosine, but inhibited by divalent cations including Ca2+, Cu2+. Its activity was completely inhibited by ascorbic acid, cysteine, 1,4-dithiothreitol, β-mercaptoethanol, sodium diethyldithiocarbamate, sodium metabisulphite, sodium sulphite and thiourea. This first report on the purification and characterisation of red Swiss chard PPO provides a basis for understanding and use of this enzyme. [Copyright &y& Elsevier]

A container experiment was conducted to test the hypothesis that uncomposted wool wastes could be used as nutrient source and growth medium constituent for container-grown plants. The treatments were: (1) rate of wool-waste application (0 or unamended control, 20, 40, 80, and 120g of wool per 8-in. pot), (2) growth medium constituents [(2.1) wool plus perlite, (2.2) wool plus peat, and (2.3) wool plus peat plus perlite], and (3) plant species (basil and Swiss chard). A single addition of 20, 40, 80, or 120g of wool-waste to Swiss chard (Beta vulgaris L.) and basil (Ocimum basilicum L.) in pots with growth medium provided four harvests of Swiss chard and five harvests of basil. Total basil yield from the five harvests was 1.6–5 times greater than the total yield from the unamended control, while total Swiss chard yield from the four harvests was 2–5 times greater relative to the respective unamended control. The addition of wool-waste to the growth medium increased Swiss chard and basil tissue N, and NO3–N and NH4–N in growth medium relative to the unamended control. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) microanalysis of wool fibers sampled at the end of the experiments indicated various levels of decomposition, with some fibers retaining their original surface structure. Furthermore, most of the wool fibers’ surfaces contained significant concentrations of S and much less N, P, or K. SEM/EDX revealed that some plant roots grow directly on wool-waste fibers suggesting either (1) root directional growth towards sites with greater nutrient concentration and/or (2) a possible role for roots or root exudates in wool decomposition. Results from this study suggest that uncomposted wool wastes can be used as soil amendment, growth medium constituent, and nutrient source for container-grown plants. [Copyright &y& Elsevier]

Leafy vegetables undergo abiotic and biotic stresses, and a series of processing steps that cause mechanical injury. Breaching the epidermis alters phyllosphere structural and nutrient conditions, resulting in successional shifts in leaf microbiota and entry of human pathogens. This study examined damage during processing of baby leaves (Swiss chard, spinach) and concomitant microbial successional events. Machine-harvesting, washing, and packaging caused major phyllosphere perturbations, with increasing levels of leaf damage. Older leaves showed most damage, but plant species was influential. Diversity estimates of bacterial and fungal communities revealed shifts in microbiota post-harvest, particularly after the washing step. Relative abundance of Pseudomonadaceae and Enterobacteriaceae increased from field to bag. Bacterial species specific to different harvesting and processing steps replaced core microbiota species. While processing is unavoidable, procedures that mitigate leaf damage can enhance shelf-life and food safety. • Intact baby leaves are damaged during harvesting and processing. • Leaf damage during and after harvest is affected by crop species. • Small round lesions appear on leaf blade and edges. • Post-harvest processing modifies leaf microbial community structure. • Highly damaged leaves should be removed before packaging. [ABSTRACT FROM AUTHOR]