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Sample records for romaine lettuce electronic

  1. Listeria monocytogenes internalizes in Romaine Lettuce grown in greenhouse conditions

    Science.gov (United States)

    Listeria monocytogenes has been implicated in a number of outbreaks involving fresh produce, including an outbreak in 2016 resulting from contaminated packaged salads. The persistence and internalization potential of L. monocytogenes in romaine lettuce was evaluated, and the persistence of two L. mo...

  2. Antineurodegenerative effect of phenolic extracts and caffeic acid derivatives in romaine lettuce on neuron-like PC-12 cells.

    Science.gov (United States)

    Im, Sung-Eun; Yoon, Hyungeun; Nam, Tae-Gyu; Heo, Ho Jin; Lee, Chang Yong; Kim, Dae-Ok

    2010-08-01

    In recent decades, romaine lettuce has been one of the fastest growing vegetables with respect to its consumption and production. An understanding is needed of the effect of major phenolic phytochemicals from romaine lettuce on biological protection for neuron-like PC-12 cells. Phenolics in fresh romaine lettuce were extracted, and then its total phenolics and total antioxidant capacity were measured spectrophotometrically. Neuroprotective effects of phenolic extract of romaine lettuce and its pure caffeic acid derivatives (caffeic, chicoric, chlorogenic, and isochlorogenic acids) in PC-12 cells were evaluated using two different in vitro methods: lactate dehydrogenase release and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assays. Total phenolics and total antioxidant capacity of 100 g of fresh romaine lettuce averaged 22.7 mg of gallic acid equivalents and 31.0 mg of vitamin C equivalents, respectively. The phenolic extract of romaine lettuce protected PC-12 cells against oxidative stress caused by H(2)O(2) in a dose-dependent manner. Isochlorogenic acid, one of the phenolics in romaine lettuce, showed stronger neuroprotection than the other three caffeic acid derivatives also found in the lettuce. Although romaine lettuce had lower levels of phenolics and antioxidant capacity compared to other common vegetables, its contribution to total antioxidant capacity and antineurodegenerative effect in human diets would be higher because of higher amounts of its daily per capita consumption compared to other common vegetables.

  3. Sensitivity of Pseudomonas fluorescens to gamma irradiation following surface inoculations on romaine lettuce and baby spinach

    Science.gov (United States)

    Irradiation of fresh fruits and vegetables is a post-harvest intervention measure often used to inactivate pathogenic food-borne microbes. We evaluated the sensitivity of Pseudomonas fluorescens strains (2-79, Q8R1, Q287) to gamma irradiation following surface inoculations on romaine lettuce and spi...

  4. Multispectral fluorescence imaging for detection of bovine feces on Romaine lettuce and baby spinach leaves

    Science.gov (United States)

    Hyperspectral fluorescence imaging with ultraviolet-A excitation was used to evaluate the feasibility of two-waveband fluorescence algorithms for the detection of bovine fecal contaminants on the abaxial and adaxial surfaces of Romaine lettuce and baby spinach leaves. Correlation analysis was used t...

  5. In-package inhibition of E.coli 0157:H7 on bulk romaine lettuce using cold plasma

    Science.gov (United States)

    Dielectric barrier discharge atmospheric cold plasma (DACP) treatment was evaluated for the inactivation of Escherichia coli O157:H7, surface morphology, color, carbon dioxide generation, and weight loss of bulk Romaine lettuce in a commercial plastic clamshell container. The lettuce samples were pa...

  6. Influence of mycorrhizal fungi on fate of E. coli 0157:H7 in soil and Salmonella in soil and internalization into romaine lettuce plants

    Science.gov (United States)

    The objectives of this study were to determine the influence of arbuscular mycorrhizal (AM) fungi on persistence of Salmonella and enterohemorrhagic E. coli O157:H7 (EHEC) within soil, and survival within Romaine lettuce. Romaine seedlings were grown with or without AM fungi, i.e., soil fungi that ...

  7. Effects of Abiotic and Biotic Stresses on the Internalization and Dissemination of Human Norovirus Surrogates in Growing Romaine Lettuce.

    Science.gov (United States)

    DiCaprio, Erin; Purgianto, Anastasia; Li, Jianrong

    2015-07-01

    Human norovirus (NoV) is the major causative agent of fresh-produce-related outbreaks of gastroenteritis; however, the ecology and persistence of human NoV in produce systems are poorly understood. In this study, the effects of abiotic and biotic stresses on the internalization and dissemination of two human NoV surrogates (murine norovirus 1 [MNV-1] and Tulane virus [TV]) in romaine lettuce were determined. To induce abiotic stress, romaine lettuce was grown under drought and flood conditions that mimic extreme weather events, followed by inoculation of soil with MNV-1 or TV. Independently, lettuce plants were infected with lettuce mosaic virus (LMV) to induce biotic stress, followed by inoculation with TV. Plants were grown for 14 days, and viral titers in harvested tissues were determined by plaque assays. It was found that drought stress significantly decreased the rates of both MNV-1 and TV internalization and dissemination. In contrast, neither flood stress nor biotic stress significantly impacted viral internalization or dissemination. Additionally, the rates of TV internalization and dissemination in soil-grown lettuce were significantly higher than those for MNV-1. Collectively, these results demonstrated that (i) human NoV surrogates can be internalized via roots and disseminated to shoots and leaves of romaine lettuce grown in soil, (ii) abiotic stress (drought) but not biotic stress (LMV infection) affects the rates of viral internalization and dissemination, and (iii) the type of virus affects the efficiency of internalization and dissemination. This study also highlights the need to develop effective measures to eliminate internalized viruses in fresh produce. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. Microbial quality of bagged baby spinach and romaine lettuce: effects of top versus bottom sampling.

    Science.gov (United States)

    Kase, Julie A; Borenstein, Stacey; Blodgett, Robert J; Feng, Peter C H

    2012-01-01

    Contamination with Escherichia coli O157:H7 and Salmonella have called into question the safety and microbial quality of bagged ready-to-eat leafy greens. This study expands on previous findings that these goods have high total bacteria counts (TBC) and coliform counts, variation in counts among different lots, that Escherichia coli is present, and disparities in counts when bags are top or bottom sampled. Nearly 100 bags of baby spinach and hearts of romaine lettuce from a single brand were subjected to both top and bottom sampling. Product was blended, and a portion serially diluted and plated to obtain TBC. Total coliform and E. coli levels were estimated by the most-probable-number (MPN) technique with ColiComplete discs. Top-sampled TBC from bags of baby spinach (48 bags, 13 different lots) ranged from 3.9 to 8.1 log CFU/g and bottom-sampled TBC ranged from 4.0 to 8.2 log CFU/g, with 52% of the bags (or 39% of the lots) producing TBC higher in bottom samples. For hearts of romaine (47 bags from 19 different lots), top-sampled bags had TBC ranging from 2.4 to 7.0 log, and bottom-sampled bags had TBC from 3.3 to 7.3 log, with 64% of the bags (or 63% of the lots) showing higher TBC in bottom samples. However, we are unable to reject the hypothesis that the top and bottom samples from either commodity contain the same TBC (P ≥ 0.08). No E. coli was detected and total coliform bacteria counts were, with few exceptions, ≥210 MPN/g, irrespective of TBC. In general, lots with the most number of days before the printed "use-by" date had lower TBC. However, the R(2) values for either baby spinach (0.4085) or hearts of romaine (0.2946) suggest that age might not be a very good predictor of higher TBC. TBC varied widely between lots and even more so within same-lot samples, as indicated by the sum of squares results. This finding, along with higher TBC in bottom samples, suggests further consideration when a microbiological sampling scheme of bagged produce is

  9. Internalization and Dissemination of Human Norovirus and Animal Caliciviruses in Hydroponically Grown Romaine Lettuce

    Science.gov (United States)

    DiCaprio, Erin; Ma, Yuanmei; Purgianto, Anastasia; Hughes, John

    2012-01-01

    Fresh produce is a major vehicle for the transmission of human norovirus (NoV) because it is easily contaminated during both pre- and postharvest stages. However, the ecology of human NoV in fresh produce is poorly understood. In this study, we determined whether human NoV and its surrogates can be internalized via roots and disseminated to edible portions of the plant. The roots of romaine lettuce growing in hydroponic feed water were inoculated with 1 × 106 RNA copies/ml of a human NoV genogroup II genotype 4 (GII.4) strain or 1 × 106 to 2 × 106 PFU/ml of animal caliciviruses (Tulane virus [TV] and murine norovirus [MNV-1]), and plants were allowed to grow for 2 weeks. Leaves, shoots, and roots were homogenized, and viral titers and/or RNA copies were determined by plaque assay and/or real-time reverse transcription (RT)-PCR. For human NoV, high levels of viral-genome RNA (105 to 106 RNA copies/g) were detected in leaves, shoots, and roots at day 1 postinoculation and remained stable over the 14-day study period. For MNV-1 and TV, relatively low levels of infectious virus particles (101 to 103 PFU/g) were detected in leaves and shoots at days 1 and 2 postinoculation, but virus reached a peak titer (105 to 106 PFU/g) at day 3 or 7 postinoculation. In addition, human NoV had a rate of internalization comparable with that of TV as determined by real-time RT-PCR, whereas TV was more efficiently internalized than MNV-1 as determined by plaque assay. Taken together, these results demonstrated that human NoV and animal caliciviruses became internalized via roots and efficiently disseminated to the shoots and leaves of the lettuce. PMID:22729543

  10. In-package inhibition of E. coli O157:H7 on bulk Romaine lettuce using cold plasma.

    Science.gov (United States)

    Min, Sea C; Roh, Si Hyeon; Niemira, Brendan A; Boyd, Glenn; Sites, Joseph E; Uknalis, Joseph; Fan, Xuetong

    2017-08-01

    Dielectric barrier discharge atmospheric cold plasma (DACP) treatment was evaluated for the inactivation of Escherichia coli O157:H7, surface morphology, color, carbon dioxide generation, and weight loss of bulk Romaine lettuce in a commercial plastic clamshell container. The lettuce samples were packed in a model bulk packaging configuration (three rows with either 1, 3, 5, or 7 layers) in the container and treated by DACP (42.6 kV, 10 min). DACP treatment reduced the number of E. coli O157:H7 in the leaf samples in the 1-, 3-, and 5-layer configurations by 0.4-0.8 log CFU/g lettuce, with no significant correlation to the sample location (P > 0.05). In the largest bulk stacking with 7 layers, a greater degree of reduction (1.1 log CFU/g lettuce) was observed at the top layer, but shaking the container increased the uniformity of the inhibition. DACP did not significantly change the surface morphology, color, respiration rate, or weight loss of the samples, nor did these properties differ significantly according to their location in the bulk stack. DACP treatment inhibited E. coli O157:H7 on bulk lettuce in clamshell containers in a uniform manner, without affecting the physical and biological properties and thus holds promise as a post-packaging process for fresh and fresh-cut fruits and vegetables. Published by Elsevier Ltd.

  11. Dielectric barrier discharge atmospheric cold plasma inhibits Escherichia coli 0157:H7, Salmonella, Listeria monocytogenes, and Tulane virus in Romaine lettuce

    Science.gov (United States)

    The present study investigated the effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus (TV) on Romaine lettuce, assessing the influences of moisture vaporization, modifi...

  12. Inactivation of Escherichia coli 0157:H7 and aerobic microorganisms in Romaine lettuce packaged in a commercial polyethylene terephthalate container using atmospheric cold plasma

    Science.gov (United States)

    The effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7 and aerobic microorganisms in Romaine lettuce packaged in a conventional commercial plastic container were evaluated during storage at 4 degrees C for 7 days. Effects ...

  13. The use of nile tilapia ( Oreochromis niloticus) cultivation wastewater for the production of romaine lettuce ( Lactuca sativa L. var. longifolia) in water recirculation system

    Science.gov (United States)

    Effendi, Hefni; Wahyuningsih, Sri; Wardiatno, Yusli

    2017-10-01

    In the recirculation aquaponic system (RAS), fish farming waste was utilized as a nutrient for plant, minimizing the water need, reducing the waste disposal into the environment, and producing the fish and plant as well. The study aimed to examine the growth of romaine lettuce ( Lactuca sativa L. var. Longifolia) in aquaponic system without the addition of artificial nutrient. The nutrient relies solely on wastewater of nile tilapia ( Oreochromis niloticus) cultivation circulated continuously on the aquaponic system. The results showed that tilapia weight reached 48.49 ± 3.92 g of T3 (tilapia, romaine lettuce, and inoculated bacteria), followed by T2 (tilapia and romaine lettuce) and T1 (tilapia) of 47.80 ± 1.97 and 45.89 ± 1.10 g after 35 days of experiment. Tilapia best performance in terms of growth and production occurred at T3 of 3.96 ± 0.44 g/day, 12.10 ± 0.63 %/day, 96.11 ± 1.44 % and 1.60 ± 0.07 for GR, SGR, SR, and FCR, respectively. It is also indicated by better water quality characteristic in this treatment. Romaine lettuce harvests of T2 and T3 showed no significant difference, with the final weight of 61.87 ± 5.59 and 57.74 ± 4.35 g. Overall, the integration of tilapia fish farming and romaine lettuce is potentially a promising aquaponic system for sustainable fish and horticulture plant production.

  14. Occurrence of Coliform and Escherichia coli Contamination and Absence of Escherichia coli O157:H7 on Romaine Lettuce from Retail Stores in the Upper Midwest.

    Science.gov (United States)

    Greve, Josephine D; Zietlow, Mark S; Miller, Kevin M; Ellingson, Jay L E

    2015-09-01

    A total of 720 whole, romaine lettuce heads were purchased from retail locations in the Upper Midwest and assessed for coliform and Escherichia coli contamination and for the presence of E. coli O157:H7. During a 16-month period (August 2010 through December 2011), coliform and E. coli counts were enumerated on Petrifilm, and the presence of E. coli O157:H7 and the virulence gene eae was evaluated by real-time PCR (qPCR). Over half (400 of 720) of the lettuce samples were processed with an immunomagnetic separation step before the qPCR assay. All retail lettuce samples were negative for E. coli O157:H7 when tested with the R.A.P.I.D. LT qPCR targeting a region of the O-antigen, and only two (0.28%) were positive for the eae gene when tested with LightCycler qPCR. On Petrifilm, coliform counts of most lettuce samples (96.4%) were between lettuce samples (98.2%) were lettuce heads. These results contribute to the limited recorded data and understanding of microbial contamination of whole romaine lettuce heads purchased from retail locations, specifically revealing the absence of E. coli O157:H7 and low levels of contamination with coliforms and other E. coli strains.

  15. Irrigation Water Sources and Time Intervals as Variables on the Presence of Campylobacter spp. and Listeria monocytogenes on Romaine Lettuce Grown in Muck Soil.

    Science.gov (United States)

    Guévremont, Evelyne; Lamoureux, Lisyanne; Généreux, Mylène; Côté, Caroline

    2017-07-01

    Irrigation water has been identified as a possible source of vegetable contamination by foodborne pathogens. Risk management for pathogens such as Campylobacter spp. and Listeria monocytogenes in fields can be influenced by the source of the irrigation water and the time interval between last irrigation and harvest. Plots of romaine lettuce were irrigated with manure-contaminated water or aerated pond water 21, 7, or 3 days prior to harvesting, and water and muck soil samples were collected at each irrigation treatment. Lettuce samples were collected at the end of the trials. The samples were tested for the presence of Campylobacter spp. and L. monocytogenes. Campylobacter coli was isolated from 33% of hog manure samples (n = 9) and from 11% of the contaminated water samples (n = 27), but no lettuce samples were positive (n = 288). L. monocytogenes was not found in manure, and only one sample of manure-contaminated irrigation water (n = 27) and one lettuce sample (n = 288) were positive. No Campylobacter or L. monocytogenes was recovered from the soil samples (n = 288). Because of the low incidence of pathogens, it was not possible to link the contamination of either soil or lettuce with the type of irrigation water. Nevertheless, experimental field trials mimicking real conditions provide new insights into the survival of two significant foodborne pathogens on romaine lettuce.

  16. Influence of mycorrhizal fungi on fate of E. coli O157:H7 and Salmonella in soil and internalization into Romaine lettuce plants.

    Science.gov (United States)

    Nicholson, April M; Gurtler, Joshua B; Bailey, Rebecca B; Niemira, Brendan A; Douds, David D

    2015-01-02

    The objectives of this study were to determine the influence of a symbiotic arbuscular mycorrhizal (AM) fungus on persistence of Salmonella and enterohemorrhagic Escherichia coli O157:H7 (EHEC) within soil, and survival within Romaine lettuce. Romaine seedlings were grown with or without AM fungi. Soil surrounding plants was inoculated with ca. 8 log CFU/plant of either Salmonella enterica or E. coli EHEC composites. Samples (soil, root, and shoot) were analyzed on days 1, 8, 15 and 22 for Salmonella and EHEC by direct plating and selective enrichment. Twenty-four hours after inoculation, populations of Salmonella and EHEC, respectively, were 4.20 and 3.24 log CFU/root, 2.52 and 1.17 log CFU/shoot, and 5.46 and 5.17 log CFU/g soil. By selective enrichment, samples tested positive for Salmonella or EHEC at day 22 at rates of 94 and 68% (shoot), 97 and 56% (root), and 100 and 75% (soil), respectively, suggesting that Salmonella has a greater propensity for survival than EHEC. Salmonella populations in soil remained as high as 4.35 log CFU/g by day 22, while EHEC populations dropped to 1.12 log CFU/g in the same amount of time. Ninety-two percent of all Romaine leaves in our study were positive for internalized Salmonella from days 8 to 22 and remained as high as 1.26 log CFU/shoot on day 22 in AM fungi+Romaine plants. There were no differences (P>0.05) between the survival of either pathogen based on the presence or absence of mycorrhizal fungi. Results of this study suggest that AM fungi do not affect the internalization and/or survival of either S. enterica or E. coli O157:H7 in Romaine lettuce seedlings. Our results should provide Romaine lettuce farmers confidence that the presence and/or application of AM fungi to crop soil is not a contributing factor to the internalization and survival of Salmonella or E. coli O157:H7 within Romaine lettuce plants. Published by Elsevier B.V.

  17. Enhanced Proton Translocating Pyrophosphatase Activity Improves Nitrogen Use Efficiency in Romaine Lettuce1[C][W][OA

    Science.gov (United States)

    Paez-Valencia, Julio; Sanchez-Lares, Jonathan; Marsh, Ellen; Dorneles, Liane T.; Santos, Mirella P.; Sanchez, Diego; Winter, Alexander; Murphy, Sean; Cox, Jennifer; Trzaska, Marcin; Metler, Jason; Kozic, Alex; Facanha, Arnoldo R.; Schachtman, Daniel; Sanchez, Charles A.; Gaxiola, Roberto A.

    2013-01-01

    Plant nitrate (NO3−) acquisition depends on the combined activities of root high- and low-affinity NO3− transporters and the proton gradient generated by the plasma membrane H+-ATPase. These processes are coordinated with photosynthesis and the carbon status of the plant. Here, we present the characterization of romaine lettuce (Lactuca sativa ‘Conquistador’) plants engineered to overexpress an intragenic gain-of-function allele of the type I proton translocating pyrophosphatase (H+-PPase) of Arabidopsis (Arabidopsis thaliana). The proton-pumping and inorganic pyrophosphate hydrolytic activities of these plants are augmented compared with control plants. Immunohistochemical data show a conspicuous increase in H+-PPase protein abundance at the vasculature of the transgenic plants. Transgenic plants displayed an enhanced rhizosphere acidification capacity consistent with the augmented plasma membrane H+-ATPase proton transport values, and ATP hydrolytic capacities evaluated in vitro. These transgenic lines outperform control plants when challenged with NO3− limitations in laboratory, greenhouse, and field scenarios. Furthermore, we report the characterization of a lettuce LsNRT2.1 gene that is constitutive up-regulated in the transgenic plants. Of note, the expression of the LsNRT2.1 gene in control plants is regulated by NO3− and sugars. Enhanced accumulation of 15N-labeled fertilizer by transgenic lettuce compared with control plants was observed in greenhouse experiments. A negative correlation between the level of root soluble sugars and biomass is consistent with the strong root growth that characterizes these transgenic plants. PMID:23307651

  18. Internalization of Sapovirus, a Surrogate for Norovirus, in Romaine Lettuce and the Effect of Lettuce Latex on Virus Infectivity

    Science.gov (United States)

    Esseili, Malak A.; Zhang, Zhenwen

    2012-01-01

    Noroviruses are the leading cause of food-borne outbreaks, including those that involve lettuce. The culturable porcine sapovirus (SaV) was used as a norovirus surrogate to study the persistence and the potential transfer of the virus from roots to leaves and from outer to inner leaves of lettuce plants. Treatment of lettuce with SaV was done through the roots of young plants, the soil, or the outer leaves of mature plants. Sampling of roots, xylem sap, and inner and outer leaves followed by RNA extraction and SaV-specific real-time reverse transcription (RT)-PCR was performed at 2 h and on postinoculation days (PID) 2, 5, 7, 14, and/or 28. When SaV was inoculated through the roots, viral RNA persisted on the roots and in the leaves until PID 28. When the virus was inoculated through the soil, viral RNA was detected on the roots and in the xylem sap until PID 14; viral RNA was detected in the leaves only until PID 2. No infectious virus was detected inside the leaves for either treatment. When SaV was inoculated through the outer leaves, viral RNA persisted on the leaves until PID 14; however, the virus did not transfer to inner leaves. Infectious viral particles on leaves were detected only at 2 h postinoculation. The milky sap (latex) of leaves, but not the roots' xylem sap, significantly decreased virus infectivity when tested in vitro. Collectively, our results showed the transfer of SaV from roots to leaves through the xylem system and the capacity of the sap of lettuce leaves to decrease virus infectivity in leaves. PMID:22752176

  19. Notice of release of iceberg, romaine, and leaf lettuce breeding lines with improved disease resistance

    Science.gov (United States)

    The Agricultural Research Service, U.S. Department of Agriculture announces the release of sixteen breeding lines of lettuce (Lactuca sativa L.). Five (SM13-Il, SM13-I2, SM13-I3, SM13-I4, and SM13-I5) of the six iceberg breeding lines can be used for whole head or salad blend production; the sixth i...

  20. Automated thinning increases uniformity of in-row spacing and plant size in romaine lettuce

    Science.gov (United States)

    Low availability and high cost of farm hand labor make automated thinners a faster and cheaper alternative to hand thinning in lettuce (Lactuca sativa L.). However, the effects of this new technology on uniformity of plant spacing and size as well as crop yield are not proven. Three experiments wer...

  1. Dielectric barrier discharge atmospheric cold plasma inhibits Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus in Romaine lettuce.

    Science.gov (United States)

    Min, Sea C; Roh, Si Hyeon; Niemira, Brendan A; Sites, Joseph E; Boyd, Glenn; Lacombe, Alison

    2016-11-21

    The present study investigated the effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus (TV) on Romaine lettuce, assessing the influences of moisture vaporization, modified atmospheric packaging (MAP), and post-treatment storage on the inactivation of these pathogens. Romaine lettuce was inoculated with E. coli O157:H7, Salmonella, L. monocytogenes (~6logCFU/g lettuce), or TV (~2logPFU/g lettuce) and packaged in either a Petri dish (diameter: 150mm, height: 15mm) or a Nylon/polyethylene pouch (152×254mm) with and without moisture vaporization. Additionally, a subset of pouch-packaged leaves was flushed with O 2 at 5% or 10% (balance N 2 ). All of the packaged lettuce samples were treated with DACP at 34.8kV for 5min and then analyzed either immediately or following post-treatment storage for 24h at 4°C to assess the inhibition of microorganisms. DACP treatment inhibited E. coli O157:H7, Salmonella, L. monocytogenes, and TV by 1.1±0.4, 0.4±0.3, 1.0±0.5logCFU/g, and 1.3±0.1logPFU/g, respectively, without environmental modifications of moisture or gas in the packages. The inhibition of the bacteria was not significantly affected by packaging type or moisture vaporization (p>0.05) but a reduced-oxygen MAP gas composition attenuated the inhibition rates of E. coli O157:H7 and TV. L. monocytogenes continued to decline by an additional 0.6logCFU/g in post-treatment cold storage for 24h. Additionally, both rigid and flexible conventional plastic packages appear to be suitable for the in-package decontamination of lettuce with DACP. Published by Elsevier B.V.

  2. Binding of Human GII.4 Norovirus Virus-Like Particles to Carbohydrates of Romaine Lettuce Leaf Cell Wall Materials

    Science.gov (United States)

    Esseili, Malak A.

    2012-01-01

    Norovirus (NoV) genogroup II genotype 4 (GII.4) strains are the dominant cause of the majority of food-borne outbreaks, including those that involve leafy greens, such as lettuce. Since human NoVs use carbohydrates of histo-blood group antigens as receptors/coreceptors, we examined the role of carbohydrates in the attachment of NoV to lettuce leaves by using virus-like particles (VLPs) of a human NoV/GII.4 strain. Immunofluorescence analysis showed that the VLPs attached to the leaf surface, especially to cut edges, stomata, and along minor veins. Binding was quantified using enzyme-linked immunosorbent assay (ELISA) performed on cell wall materials (CWM) from innermost younger leaves and outermost lamina of older leaves. The binding to CWM of older leaves was significantly (P lettuce CWM by utilizing multiple carbohydrate moieties. This binding may enhance virus persistence on the leaf surface and prevent effective decontamination. PMID:22138991

  3. Light exposure during storage preserving soluble sugar and l-ascorbic acid content of minimally processed romaine lettuce (Lactuca sativa L.var. longifolia).

    Science.gov (United States)

    Zhan, Lijuan; Hu, Jinqiang; Ai, Zhilu; Pang, Lingyun; Li, Yu; Zhu, Meiyun

    2013-01-01

    Minimally processed romaine lettuce (MPRL) leaves were stored in light condition (2500lux) or darkness at 4°C for 7d. Light exposure significantly delayed the degradation of chlorophyll and decrease of glucose, reducing sugar, and sucrose content, and thus preserved more total soluble solid (TSS) content at the end of storage in comparison with darkness. While, it did not influenced starch content that progressively decreased over time. The l-ascorbic acid (AA) accumulated in light-stored leaves, but deteriorated in dark-stored leaves during storage. The dehydroascorbic acid (DHA) increased in all leaves stored in both light and dark condition, of which light condition resulted in less DHA than darkness. In addition, the fresh weight loss and dry matter significantly increased and these increases were accelerated by light exposure. Conclusively, light exposure in applied intensity effectively alleviated MPRL quality deterioration by delaying the decreases of pigments, soluble sugar, TSS content and accumulating AA. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Sustainable lettuce: Adaptability to uncertain production conditions

    Science.gov (United States)

    Lettuce is a popular and widely consumed leafy vegetable. California and Arizona annually produce more than 250,000 acres of iceberg, romaine, leaf, and specialty types of lettuce, supplying more than 95% of the U.S market as well as exports to Canada and other countries. These states have dominat...

  5. Agronomic aspects of strip intercropping lettuce with alyssum for biological control of aphids

    OpenAIRE

    Brennan, Eric B.

    2013-01-01

    Organic lettuce growers in California typically use insectary strips of alyssum (Lobularia maritima (L.) Desv.) to attract hoverflies (Syrphidae) that provide biological control of aphids. A two year study with transplanted organic romaine lettuce in Salinas, California investigated agronomic aspects of lettuce monoculture and lettuce-alyssum strip intercropping on beds in replacement intercropping treatments where alyssum transplants replaced 2 to 8% of the lettuce transplants, and in additi...

  6. Efficacy of chlorine, acidic electrolyzed water and aqueous chlorine dioxide solutions to decontaminate Escherichia coli O157:H7 from lettuce leaves.

    Science.gov (United States)

    Keskinen, Lindsey A; Burke, Angela; Annous, Bassam A

    2009-06-30

    This study compared the efficacy of chlorine (20-200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20-200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20-200 ppm chlorite ion concentration, TriNova) washes in reducing populations of Escherichia coli O157:H7 on artificially inoculated lettuce. Fresh-cut leaves of Romaine or Iceberg lettuce were inoculated by immersion in water containing E. coli O157:H7 (8 log CFU/ml) for 5 min and dried in a salad spinner. Leaves (25 g) were then washed for 2 min, immediately or following 24 h of storage at 4 degrees C. The washing treatments containing chlorite ion concentrations of 100 and 200 ppm were the most effective against E. coli O157:H7 populations on Iceberg lettuce, with log reductions as high as 1.25 log CFU/g and 1.05 log CFU/g for TriNova and Sanova wash treatments, respectively. All other wash treatments resulted in population reductions of less than 1 log CFU/g. Chlorine (200 ppm), TriNova, Sanova, and acidic electrolyzed water were all equally effective against E. coli O157:H7 on Romaine, with log reductions of approximately 1 log CFU/g. The 20 ppm chlorine wash was as effective as the deionized water wash in reducing populations of E. coli O157:H7 on Romaine and Iceberg lettuce. Scanning electron microscopy indicated that E. coli O157:H7 that was incorporated into biofilms or located in damage lettuce tissue remained on the lettuce leaf, while individual cells on undamaged leaf surfaces were more likely to be washed away.

  7. Role of syrphid larvae and other predators in suppressing aphid infestations in organic lettuce on California's Central Coast.

    Science.gov (United States)

    Smith, Hugh A; Chaney, William E; Bensen, Tiffany A

    2008-10-01

    Organic lettuce, Lactuca sativa L., growers on the Central Coast of California rely on conservation biological control to manage Nasonovia ribisnigri Mosley (Hemiptera: Aphididae) and other aphid pests of lettuce. In 2006, we carried out five replicated field trials to determine the importance of syrphid larvae in the suppression of N. ribisnigri and other aphids infesting organic romaine lettuce. We used Entrust, a spinosad-based insecticide approved for use on organic farms, to suppress syrphid larvae in aphid-infested romaine. Romaine treated with Entrust was unmarketable at harvest because of aphid infestation, whereas insecticide-free romaine was marketable. Syrphid larvae composed 85% or more of total predators in most trials, and they were the only predators consistently recovered from romaine that was infested with aphids early and largely aphid-free by harvest. The species mix of nonsyrphid predators varied from site to site. Applications of Entrust suppressed nonsyrphid predators in two trials, and so was an imperfect tool for selectively suppressing syrphid larvae. The relative importance of syrphid larvae and other predators in the conservation biological control of aphids in organic romaine is discussed. We conclude that syrphid larvae are primarily responsible for the suppression of aphids in organic romaine on California's Central Coast.

  8. Lettuce breeding

    Science.gov (United States)

    In the 2016-2017 period, major efforts targeted resistance to lettuce drop caused by Sclerotinia species, Verticillium wilt, Fusarium wilt, bacterial leaf spot, corky root, downy mildew, drought tolerance, lettuce aphid, tipburn, shelf-life of salad-cut lettuce, and multiple disease resistance. Resi...

  9. Phenolic composition and related antioxidant properties in differently colored lettuces: a study by electron paramagnetic resonance (EPR) kinetics.

    Science.gov (United States)

    Pérez-López, Usue; Pinzino, Calogero; Quartacci, Mike Frank; Ranieri, Annamaria; Sgherri, Cristina

    2014-12-10

    Differently colored lettuce (Lactuca sativa L.) cultivars (green, green/red, and red) were studied to correlate their phenolic composition with their antioxidant kinetic behavior. Electron paramagnetic resonance (EPR) was employed to monitor decay kinetics of 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)), which allowed the identification of three differently paced antioxidants. The results showed that as long as lettuce had higher red pigmentation, the hydrophilic antioxidant capacity increased together with the contents in free and conjugated phenolic acids, free and conjugated flavonoids, and anthocyanins. EPR allowed the identification of slow-rate antioxidants in green and green/red cultivars, intermediate-rate antioxidants in green, green/red, and red cultivars, and fast-rate antioxidants in green/red and red cultivars. At present, the different kinetic behaviors cannot be attributed to a specific antioxidant, but it is suggested that the flavonoid quercetin accounted for the majority of the intermediate-rate antioxidants, whereas the anthocyanins accounted for the majority of the fast-rate antioxidants.

  10. Reframing Romaine Brooks' heroic queer modernism.

    Science.gov (United States)

    Langer, Cassandra L

    2010-01-01

    Modernism was not a wholesale embracing of Greenberg's definition as abstracting, non-objective, and autonomous. The expatriate U.S. artist and lesbian Romaine Brooks politicized her portraits of females based on a queer combination of the Byronic erotic and Baudelaire's modern dandy. Her execution of her queer modernist aesthetics re-presents female heroes as part of a self-reflective dynamic of lesbian modernity that emphasizes the ambiguity of normative gender binaries and plays with style, personality, and impersonation as disrupting to bourgeoisie mores. My focus is on how Brooks shatters normative conventions of portraiture in her revolutionary critique of heteronormativity.

  11. Phyllosphere Microbiota Composition and Microbial Community Transplantation on Lettuce Plants Grown Indoors

    Science.gov (United States)

    Williams, Thomas R.

    2014-01-01

    ABSTRACT The aerial surfaces of plants, or phyllosphere, are microbial habitats important to plant and human health. In order to accurately investigate microbial interactions in the phyllosphere under laboratory conditions, the composition of the phyllosphere microbiota should be representative of the diversity of microorganisms residing on plants in nature. We found that Romaine lettuce grown in the laboratory contained 10- to 100-fold lower numbers of bacteria than age-matched, field-grown lettuce. The bacterial diversity on laboratory-grown plants was also significantly lower and contained relatively higher proportions of Betaproteobacteria as opposed to the Gammaproteobacteria-enriched communities on field lettuce. Incubation of field-grown Romaine lettuce plants in environmental growth chambers for 2 weeks resulted in bacterial cell densities and taxa similar to those on plants in the field but with less diverse bacterial populations overall. In comparison, the inoculation of laboratory-grown Romaine lettuce plants with either freshly collected or cryopreserved microorganisms recovered from field lettuce resulted in the development of a field-like microbiota on the lettuce within 2 days of application. The survival of an inoculated strain of Escherichia coli O157:H7 was unchanged by microbial community transfer; however, the inoculation of E. coli O157:H7 onto those plants resulted in significant shifts in the abundance of certain taxa. This finding was strictly dependent on the presence of a field-associated as opposed to a laboratory-associated microbiota on the plants. Phyllosphere microbiota transplantation in the laboratory will be useful for elucidating microbial interactions on plants that are important to agriculture and microbial food safety. PMID:25118240

  12. Variability of phenolic content and antioxidant activity of two lettuce varieties under Fe deficiency.

    Science.gov (United States)

    Msilini, Najoua; Oueslati, Samia; Amdouni, Thouraya; Chebbi, Mohamed; Ksouri, Riadh; Lachaâl, Mokhtar; Ouerghi, Zeineb

    2013-06-01

    Fe deficiency affects food growth and quality in calcareous soils. In this study, the effect of Fe deficiency on growth parameters, phenolic content and antioxidant capacities of two lettuce shoots varieties (Romaine and Vista) were investigated. Fresh matter production, pigment (chlorophyll and carotenoid) and Fe2+ content were significantly reduced by Fe deficiency in both varieties. However, restriction of these parameters was particularly pronounced in Romaine variety as compared to Vista. Moreover, Fe deficiency caused decreases in the activity of antioxidant enzymes such as catalase and guaiacol peroxidase, whereas ascorbate peroxidase and malondialdehyde concentrations were not significantly affected. On the other hand, Fe deficiency in Vista variety induced an increase in polyphenol and flavonoid content as compared to Romaine variety. In addition, total antioxidant capacity and antiradical test against DPPH radical decreased in leaves of Romaine variety after 15 days of treatment. These results suggest that the higher polyphenol content in Vista variety supports the involvement of these components in the stability of antioxidant capacities and then in its protection against oxidative damage generated by Fe deficiency in lettuce plants. © 2012 Society of Chemical Industry.

  13. Water lettuce

    African Journals Online (AJOL)

    Nutritive values, Mineral and Antioxidant properties of Pistia stratiotes (Water lettuce). 1R .S.U. Wasagu ... The use of plants as medicines predates written human history and some of ... used to maintain health, as well as to prevent, diagnose ...

  14. Oxygenated phosphine fumigation for control of Nasonovia ribisnigri (Homoptera: Aphididae) on harvested lettuce.

    Science.gov (United States)

    Liu, Yong-Biao

    2012-06-01

    Low temperature regular phosphine fumigations under the normal oxygen level and oxygenated phosphine fumigations under superatmospheric oxygen levels were compared for efficacy against the aphid, Nasonovia ribisnigri (Mosley), and effects on postharvest quality of romaine and head lettuce. Low temperature regular phosphine fumigation was effective against the aphid. However, a 3 d treatment with high phosphine concentrations of > or = 2,000 ppm was needed for complete control of the aphid. Oxygen greatly increased phosphine toxicity and significantly reduced both treatment time and phosphine concentration for control of N. ribisnigri. At 1,000 ppm phosphine, 72 h regular fumigations at 6 degrees C did not achieve 100% mortality of the aphid. The 1,000 ppm phosphine fumigation under 60% O2 killed all aphids in 30 h. Both a 72 h regular fumigation with 2,200 ppm phosphine and a 48 h oxygenated fumigation with 1,000 ppm phosphine under 60% O2 were tested on romaine and head lettuce at 3 degrees C. Both treatments achieved complete control of N. ribisnigri. However, the 72 h regular fumigation resulted in significantly higher percentages of lettuce with injuries and significantly lower lettuce internal quality scores than the 48 h oxygenated phosphine fumigation. Although the oxygenated phosphine fumigation also caused injuries to some treated lettuce, lettuce quality remained very good and the treatment is not expected to have a significant impact on marketability of the lettuce. This study demonstrated that oxygenated phosphine fumigation was more effective and less phytotoxic for controlling N. ribisnigri on harvested lettuce than regular phosphine fumigation and is promising for practical use.

  15. Romain Rolland: une rencontre avec l’Inde

    Directory of Open Access Journals (Sweden)

    María Ángeles Caamaño Piñeiro

    2015-04-01

    Full Text Available The aim of this article is to discuss the thoughts that Romain Rolland made about India, a subject which has curiously attracted little critical attention. A pioneer intercultural studies, Romain Rolland laid the ground for a future development of the cultural relationship between Europe and India. Three fundamental texts conform the approach to India made by this writer. Three biographies about Gandhi, Ramakrishna and Vivekananda. These biographical works are constructed according to a non-duality logic which coincides with that of the Advaita Vedanta in stylistic and conceptual terms.

  16. Effect of Salt Stress on Morphological Traits of Lettuce Genotypes (Lactuca Sativa L.

    Directory of Open Access Journals (Sweden)

    maryam zare

    2017-02-01

    Romaine lettuce long green Teresa genotype, respectivly. Increasing salinity led to significant reduction (p≤0.01 in the plant length lettuce in all genotypes. Root and plant fresh weight lettuce genotypes were significantly (p≤0.01 influenced by different levels of salinity. The greatest amount in root and plant fresh weight lettuce genotypes were obtained in the control treatment and the lowest amount at the level of 4 dS/m. Root and plant dry weight lettuce genotypes were significantly (p≤0.01 influenced by the salinity. Root and plant dry weight decreased with increasing salinity. So that the greatest amount of root and plant dry weight lettuce genotypes were obtained in control treatment and the lowest amount at the level of 4 dS/m.. The results showed that root and plant length ,root fresh and dry weight, plant fresh and dry weight and leaf length and width reduced with increasing salinity. The clustering pattern the genotypes were grouped into 3 clusters based on their charachters at 4 dS/m salinity. The first cluster were placed in salt tolerant groups, while the other genotypes were clustered into moderately tolerant cluster. Romaine lettuce long green Teresa genotype was placed in salt-tolerant group and Lettuce Everest, Lettuce May Queen, Curly endive hair angel, Cabbage Milan Aubervilliers and Romaine lettuce long blonde Galaica were placed in salt-sensitive group.

  17. Effect of Salt Stress on Morphological Traits of Lettuce Genotypes (Lactuca Sativa L.

    Directory of Open Access Journals (Sweden)

    maryam zare

    2017-09-01

    Romaine lettuce long green Teresa genotype, respectivly. Increasing salinity led to significant reduction (p≤0.01 in the plant length lettuce in all genotypes. Root and plant fresh weight lettuce genotypes were significantly (p≤0.01 influenced by different levels of salinity. The greatest amount in root and plant fresh weight lettuce genotypes were obtained in the control treatment and the lowest amount at the level of 4 dS/m. Root and plant dry weight lettuce genotypes were significantly (p≤0.01 influenced by the salinity. Root and plant dry weight decreased with increasing salinity. So that the greatest amount of root and plant dry weight lettuce genotypes were obtained in control treatment and the lowest amount at the level of 4 dS/m.. The results showed that root and plant length ,root fresh and dry weight, plant fresh and dry weight and leaf length and width reduced with increasing salinity. The clustering pattern the genotypes were grouped into 3 clusters based on their charachters at 4 dS/m salinity. The first cluster were placed in salt tolerant groups, while the other genotypes were clustered into moderately tolerant cluster. Romaine lettuce long green Teresa genotype was placed in salt-tolerant group and Lettuce Everest, Lettuce May Queen, Curly endive hair angel, Cabbage Milan Aubervilliers and Romaine lettuce long blonde Galaica were placed in salt-sensitive group.

  18. Influence of surface polysaccharides of Escherichia coli O157:H7 on plant defense response and survival of the human enteric pathogen on Arabidopsis thaliana and lettuce (Lactuca sativa).

    Science.gov (United States)

    Jang, Hyein; Matthews, Karl R

    2018-04-01

    This study aimed to determine the influence of bacterial surface polysaccharides (cellulose, colanic acid, and lipopolysaccharide; LPS) on the colonization or survival of Escherichia coli O157:H7 on plants and the plant defense response. Survival of E. coli O157:H7 were evaluated on Arabidopsis thaliana and romaine lettuce as a model plant and an edible crop (leafy vegetable), respectively. The population of the wild-type strain of E. coli O157:H7 on Arabidopsis plants and lettuce was significantly (P lettuce regardless of day post-inoculation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Lettuce contact allergy.

    Science.gov (United States)

    Paulsen, Evy; Andersen, Klaus E

    2016-02-01

    Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22%. The majority of cases are non-occupational, and may partly be caused by cross-reactivity. The sesquiterpene lactone mix seems to be a poor screening agent for lettuce contact allergy, as the prevalence of positive reactions is significantly higher in non-occupationally sensitized patients. Because of the easy degradability of lettuce allergens, it is recommended to patch test with freshly cut lettuce stem and supplement this with Compositae mix. As contact urticaria and protein contact dermatitis may present as dermatitis, it is important to perform prick-to-prick tests, and possibly scratch patch tests as well. Any person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  20. Stability of carotenoids and tocopherols in ready-to-eat baby-leaf lettuce and salad rocket during low-temperature storage.

    Science.gov (United States)

    Saini, Ramesh Kumar; Shang, Xiao Min; Ko, Eun Young; Choi, Jeong Hee; Keum, Young-Soo

    2015-08-01

    Minimally processed ready-to-eat baby-leaf vegetables (BLVs) are the most convenient source to include the health beneficial bioactive in the daily diet. In the present study, the visual quality and storage stability of carotenoids, tocopherols were investigated in lettuce (green and red romaine) and salad rocket BLVs. The commercially packed samples of BLVs were stored at 0 °C and 4 °C in dark conditions and analyzed after 0, 2, 4, 8 and 12 days of storage. All the studied samples were found in better visual quality up to eight days of storage at both the temperatures. In most cases, the quality was correlated with the chlorophyll contents. The highest significant (p tocopherols were observed in samples stored at 4 °C. Also, carotenoids and tocopherols are maximum stable in green and red romaine lettuce, respectively.

  1. Effects of gamma irradiation on the survival of Pseudomonas fluorescens inoculated on romaine lettuce

    Science.gov (United States)

    Irradiation of fresh fruits and vegetables has been utilized as a post-harvest intervention measure for inactivation of microbial pathogens. Pseudomonas fluorescens 2-79, Q8R1, Q287 are non-plant pathogenic, non-pectolytic strains of a potential biocontrol agent. We tested the sensitivity of these s...

  2. Lettuce contact allergy

    DEFF Research Database (Denmark)

    Paulsen, Evy; Andersen, Klaus E

    2016-01-01

    Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present...... person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy.......Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present...... new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22...

  3. Fate of Salmonella enterica in a mixed ingredient salad containing lettuce, cheddar cheese, and cooked chicken meat.

    Science.gov (United States)

    Bovo, Federica; De Cesare, Alessandra; Manfreda, Gerardo; Bach, Susan; Delaquis, Pascal

    2015-03-01

    Food service and retail sectors offer consumers a variety of mixed ingredient salads that contain fresh-cut vegetables and other ingredients such as fruits, nuts, cereals, dairy products, cooked seafood, cooked meat, cured meats, or dairy products obtained from external suppliers. Little is known about the behavior of enteric bacterial pathogens in mixed ingredient salads. A model system was developed to examine the fate of Salmonella enterica (inoculum consisting of S. enterica serovars Agona, Typhimurium, Enteritidis, Brandenberg, and Kentucky) on the surface of romaine lettuce tissues incubated alone and in direct contact with Cheddar cheese or cooked chicken. S. enterica survived but did not grow on lettuce tissues incubated alone or in contact with Cheddar cheese for 6 days at either 6 or 14°C. In contrast, populations increased from 2.01 ± 0.22 to 9.26 ± 0.22 CFU/cm(2) when lettuce washed in water was incubated in contact with cooked chicken at 14°C. Populations on lettuce leaves were reduced to 1.28 ± 0.14 CFU/cm(2) by washing with a chlorine solution (70 ppm of free chlorine) but increased to 8.45 ± 0.22 CFU/cm(2) after 6 days at 14°C. Experimentation with a commercial product in which one third of the fresh-cut romaine lettuce was replaced with inoculated lettuce revealed that S. enterica populations increased by 4 log CFU/g during storage for 3 days at 14°C. These findings indicate that rapid growth of bacterial enteric pathogens may occur in mixed ingredient salads; therefore, strict temperature control during the manufacture, distribution, handling, and storage of these products is critical.

  4. [The Sigmund Freud - Romain Rolland letters (1923-1936)].

    Science.gov (United States)

    Vermorel, H; Vermorel, M

    1989-01-01

    This correspondence evolves on three planes: that of a dialogue between an atheistic Jew and a solitary Christian interested in mysticism, that is also a dialogue between a Frenchman attracted by German culture and an inhabitant of Vienna who was particularly attached to France, as well as being an exchange of ideas on the origins of literary and scientific creation. The central debate on the question of the oceanic heeling suggested by Romain Rolland led Sigmund Freud to take up again an essential point in his self-analysis that had remained unanalysed at the time of his exchange with Fliess: his relationship with an original mother image.

  5. Effects of household washing on bacterial load and removal of Escherichia coli from lettuce and "ready-to-eat" salads.

    Science.gov (United States)

    Uhlig, Elisabeth; Olsson, Crister; He, Jiayi; Stark, Therese; Sadowska, Zuzanna; Molin, Göran; Ahrné, Siv; Alsanius, Beatrix; Håkansson, Åsa

    2017-11-01

    Customer demands for fresh salads are increasing, but leafy green vegetables have also been linked to food-borne illness due to pathogens such as Escherichia coli O157:H7. As a safety measure, consumers often wash leafy vegetables in water before consumption. In this study, we analyzed the efficiency of household washing to reduce the bacterial content. Romaine lettuce and ready-to-eat mixed salad were washed several times in flowing water at different rates and by immersing the leaves in water. Lettuce was also inoculated with E. coli before washing. Only washing in a high flow rate (8 L/min) resulted in statistically significant reductions ( p  < .05), "Total aerobic count" was reduced by 80%, and Enterobacteriaceae count was reduced by 68% after the first rinse. The number of contaminating E. coli was not significantly reduced. The dominating part of the culturable microbiota of the washed lettuce was identified by rRNA 16S sequencing of randomly picked colonies. The majority belonged to Pseudomonadaceae , but isolates from Enterobacteriaceae and Staphylococcaceaceae were also frequently found. This study shows the inefficiency of tap water washing methods available for the consumer when it comes to removal of bacteria from lettuce. Even after washing, the lettuce contained high levels of bacteria that in a high dose and under certain circumstances may constitute a health risk.

  6. Leaf microbiota in an agroecosystem: spatiotemporal variation in bacterial community composition on field-grown lettuce.

    Science.gov (United States)

    Rastogi, Gurdeep; Sbodio, Adrian; Tech, Jan J; Suslow, Trevor V; Coaker, Gitta L; Leveau, Johan H J

    2012-10-01

    The presence, size and importance of bacterial communities on plant leaf surfaces are widely appreciated. However, information is scarce regarding their composition and how it changes along geographical and seasonal scales. We collected 106 samples of field-grown Romaine lettuce from commercial production regions in California and Arizona during the 2009-2010 crop cycle. Total bacterial populations averaged between 10(5) and 10(6) per gram of tissue, whereas counts of culturable bacteria were on average one (summer season) or two (winter season) orders of magnitude lower. Pyrosequencing of 16S rRNA gene amplicons from 88 samples revealed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the most abundantly represented phyla. At the genus level, Pseudomonas, Bacillus, Massilia, Arthrobacter and Pantoea were the most consistently found across samples, suggesting that they form the bacterial 'core' phyllosphere microbiota on lettuce. The foliar presence of Xanthomonas campestris pv. vitians, which is the causal agent of bacterial leaf spot of lettuce, correlated positively with the relative representation of bacteria from the genus Alkanindiges, but negatively with Bacillus, Erwinia and Pantoea. Summer samples showed an overrepresentation of Enterobacteriaceae sequences and culturable coliforms compared with winter samples. The distance between fields or the timing of a dust storm, but not Romaine cultivar, explained differences in bacterial community composition between several of the fields sampled. As one of the largest surveys of leaf surface microbiology, this study offers new insights into the extent and underlying causes of variability in bacterial community composition on plant leaves as a function of time, space and environment.

  7. Leaf microbiota in an agroecosystem: spatiotemporal variation in bacterial community composition on field-grown lettuce

    Science.gov (United States)

    Rastogi, Gurdeep; Sbodio, Adrian; Tech, Jan J; Suslow, Trevor V; Coaker, Gitta L; Leveau, Johan H J

    2012-01-01

    The presence, size and importance of bacterial communities on plant leaf surfaces are widely appreciated. However, information is scarce regarding their composition and how it changes along geographical and seasonal scales. We collected 106 samples of field-grown Romaine lettuce from commercial production regions in California and Arizona during the 2009–2010 crop cycle. Total bacterial populations averaged between 105 and 106 per gram of tissue, whereas counts of culturable bacteria were on average one (summer season) or two (winter season) orders of magnitude lower. Pyrosequencing of 16S rRNA gene amplicons from 88 samples revealed that Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria were the most abundantly represented phyla. At the genus level, Pseudomonas, Bacillus, Massilia, Arthrobacter and Pantoea were the most consistently found across samples, suggesting that they form the bacterial ‘core' phyllosphere microbiota on lettuce. The foliar presence of Xanthomonas campestris pv. vitians, which is the causal agent of bacterial leaf spot of lettuce, correlated positively with the relative representation of bacteria from the genus Alkanindiges, but negatively with Bacillus, Erwinia and Pantoea. Summer samples showed an overrepresentation of Enterobacteriaceae sequences and culturable coliforms compared with winter samples. The distance between fields or the timing of a dust storm, but not Romaine cultivar, explained differences in bacterial community composition between several of the fields sampled. As one of the largest surveys of leaf surface microbiology, this study offers new insights into the extent and underlying causes of variability in bacterial community composition on plant leaves as a function of time, space and environment. PMID:22534606

  8. Lettuce and spinach breeding

    Science.gov (United States)

    Lettuce and spinach production is beset by numerous biotic an abiotic challenges, thus the leafy-vegetable industry of California requires continued development of improved, adapted cultivars to meet new disease and insect problems, changes in the market, and changes in growing procedures. The lettu...

  9. Analysis of eleven phenolic compounds including novel p-coumaroyl derivatives in lettuce (Lactuca sativa L.) by ultra-high-performance liquid chromatography with photodiode array and mass spectrometry detection.

    Science.gov (United States)

    Ribas-Agustí, Albert; Gratacós-Cubarsí, Marta; Sárraga, Carmen; García-Regueiro, José-Antonio; Castellari, Massimo

    2011-01-01

    Lettuce is a widely consumed vegetable and a good source of phenolic compounds. Several factors (genetic, agronomical and environmental) can influence the lettuce composition; their effects are not completely defined and more studies are needed on this topic. To develop an improved ultra-high-performance liquid chromatography (UHPLC) method to quantify the main target intact phenolic compounds in lettuce. UHPLC identification of the compounds was supported by PAD spectra and MS(n) analyses. Quantification was carried out by PAD, by creating matrix-matched calibration curves at the specific wavelength for each compound. Sample pretreatment was simplified, with neither purification nor hydrolysis steps. Chromatographic conditions were chosen to minimise matrix interferences and to give a suitable separation of the major phenolic compounds within 27 min. The method allowed the quantification of 11 intact phenolic compounds in Romaine lettuces, including phenolic acids (caffeoyl and p-coumaroyl esters) and flavonoids (quercetin glycosides). Four p-coumaroyl esters were tentatively identified and quantified for the first time in lettuce. The main intact phenolic compounds, including four novel p-coumaroyl esters, were simultaneously quantified in lettuce with optimal performances and a reduced total time of analysis. These findings make headway in the understanding of the lettuce phytochemicals with potential nutritional relevance. Copyright © 2011 John Wiley & Sons, Ltd.

  10. Season, Irrigation, Leaf Age, and Escherichia coli Inoculation Influence the Bacterial Diversity in the Lettuce Phyllosphere

    Science.gov (United States)

    Williams, Thomas R.; Moyne, Anne-Laure; Harris, Linda J.; Marco, Maria L.

    2013-01-01

    The developmental and temporal succession patterns and disturbance responses of phyllosphere bacterial communities are largely unknown. These factors might influence the capacity of human pathogens to persist in association with those communities on agriculturally-relevant plants. In this study, the phyllosphere microbiota was identified for Romaine lettuce plants grown in the Salinas Valley, CA, USA from four plantings performed over 2 years and including two irrigation methods and inoculations with an attenuated strain of Escherichia coli O157:H7. High-throughput DNA pyrosequencing of the V5 to V9 variable regions of bacterial 16S rRNA genes recovered in lettuce leaf washes revealed that the bacterial diversity in the phyllosphere was distinct for each field trial but was also strongly correlated with the season of planting. Firmicutes were generally most abundant in early season (June) plantings and Proteobacteria comprised the majority of bacteria recovered later in the year (August and October). Comparisons within individual field trials showed that bacterial diversity differed between sprinkler (overhead) and drip (surface) irrigated lettuce and increased over time as the plants grew. The microbiota were also distinct between control and E. coli O157:H7-inoculated plants and between E. coli O157:H7-inoculated plants with and without surviving pathogen cells. The bacterial inhabitants of the phyllosphere therefore appear to be affected by seasonal, irrigation, and biological factors in ways that are relevant for assessments of fresh produce food safety. PMID:23844230

  11. Wild lettuce (Lactuca virosa) toxicity

    OpenAIRE

    Besharat, Sima; Besharat, Mahsa; Jabbari, Ali

    2009-01-01

    Wild lettuce (Lactuca virosa) can cause toxic effects when eaten. Wild lettuce grows in the north of Iran and some natives consume it unaware of its adverse side effects. We describe eight patients with manifestations of wild lettuce toxicity, admitted to a general hospital affiliated to the Golestan University of Medical Sciences. All the patients recovered (although one had to spend 48 h in the intensive care unit) and no chronic complications were reported. A clinical suspicion of toxicity...

  12. LC-MS Untargeted Metabolomics To Explain the Signal Metabolites Inducing Browning in Fresh-Cut Lettuce.

    Science.gov (United States)

    García, Carlos J; García-Villalba, Rocío; Gil, María I; Tomas-Barberan, Francisco A

    2017-06-07

    Enzymatic browning is one of the main causes of quality loss in lettuce as a prepared and ready-to-eat cut salad. An untargeted metabolomics approach using UPLC-ESI-QTOF-MS was performed to explain the wound response of lettuce after cutting and to identify the metabolites responsible of browning. Two cultivars of Romaine lettuce with different browning susceptibilities were studied at short time intervals after cutting. From the total 5975 entities obtained from the raw data after alignment, filtration reduced the number of features to 2959, and the statistical analysis found that only 1132 entities were significantly different. Principal component analysis (PCA) clearly showed that these samples grouped according to cultivar and time after cutting. From those, only 15 metabolites belonging to lysophospholipids, oxylipin/jasmonate metabolites, and phenolic compounds were able to explain the browning process. These selected metabolites showed different trends after cutting; some decreased rapidly, others increased but decreased thereafter, whereas others increased during the whole period of storage. In general, the fast-browning cultivar showed a faster wound response and a higher raw intensity of some key metabolites than the slow-browning one. Just after cutting, the fast-browning cultivar contained 11 of the 15 browning-associated metabolites, whereas the slow-browning cultivar only had 5 of them. These metabolites could be used as biomarkers in breeding programs for the selection of lettuce cultivars with lower browning potential for fresh-cut applications.

  13. Modeling uptake kinetics of cadmium by field-grown lettuce

    Energy Technology Data Exchange (ETDEWEB)

    Chen Weiping [Department of Environmental Sciences, University of California, 900 University Avenue, Riverside, CA 92521 (United States)], E-mail: chenweip@yahoo.com.cn; Li Lianqing [Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095 (China); Chang, Andrew C.; Wu Laosheng [Department of Environmental Sciences, University of California, 900 University Avenue, Riverside, CA 92521 (United States); Kwon, Soon-Ik [Agricultural Environmental and Ecology Division, National Institute of Agricultural Science and Technology, Suwon 441-707 (Korea, Republic of); Bottoms, Rick [Desert Research and Extension Center, 1004 East Holton Road, El Centro, CA 92243 (United States)

    2008-03-15

    Cadmium uptake by field grown Romaine lettuce treated with P-fertilizers of different Cd levels was investigated over an entire growing season. Results indicated that the rate of Cd uptake at a given time of the season can be satisfactorily described by the Michaelis-Menten kinetics, that is, plant uptake increases as the Cd concentration in soil solution increases, and it gradually approaches a saturation level. However, the rate constant of the Michaelis-Menten kinetics changes over the growing season. Under a given soil Cd level, the cadmium content in plant tissue decreases exponentially with time. To account for the dynamic nature of Cd uptake, a kinetic model integrating the time factor was developed to simulate Cd plant uptake over the growing season: C{sub Plant} = C{sub Solution} . PUF{sub max} . exp[-b . t], where C{sub Plant} and C{sub Solution} refer to the Cd content in plant tissue and soil solution, respectively, PUF{sub max} and b are kinetic constants. - A kinetic model was developed to evaluate the uptake of Cd under field conditions.

  14. Modeling uptake kinetics of cadmium by field-grown lettuce

    International Nuclear Information System (INIS)

    Chen Weiping; Li Lianqing; Chang, Andrew C.; Wu Laosheng; Kwon, Soon-Ik; Bottoms, Rick

    2008-01-01

    Cadmium uptake by field grown Romaine lettuce treated with P-fertilizers of different Cd levels was investigated over an entire growing season. Results indicated that the rate of Cd uptake at a given time of the season can be satisfactorily described by the Michaelis-Menten kinetics, that is, plant uptake increases as the Cd concentration in soil solution increases, and it gradually approaches a saturation level. However, the rate constant of the Michaelis-Menten kinetics changes over the growing season. Under a given soil Cd level, the cadmium content in plant tissue decreases exponentially with time. To account for the dynamic nature of Cd uptake, a kinetic model integrating the time factor was developed to simulate Cd plant uptake over the growing season: C Plant = C Solution . PUF max . exp[-b . t], where C Plant and C Solution refer to the Cd content in plant tissue and soil solution, respectively, PUF max and b are kinetic constants. - A kinetic model was developed to evaluate the uptake of Cd under field conditions

  15. CONSUMER ATTITUDES TOWARD ORGANICALLY GROWN LETTUCE

    OpenAIRE

    Wolf, Marianne McGarry; Johnson, Bradey; Cochran, Kerry; Hamilton, Lynn L.

    2002-01-01

    This research shows that approximately 29 percent of lettuce purchases in California expect to purchase an organically grown lettuce product in the future. Organic lettuce purchasers are more likely to be female, have a higher household income and a higher level of education. Consumers are concerned with the freshness, quality, price, and environmental impact of the lettuce they purchase.

  16. Sanitizer efficacy in preventing cross-contamination of heads of lettuce during retail crisping.

    Science.gov (United States)

    Jung, Yangjin; Jang, Hyein; Guo, Mengqi; Gao, Jingwen; Matthews, Karl R

    2017-06-01

    This study was conducted to provide information regarding mitigation of cross-contamination through the use of sanitizer during crisping at retail outlets. Seven non-inoculated heads and one inoculated head (≈5 log CFU/g) of lettuce were placed into commercial sink filled with 76 L of tap water (TW), electrolyzed water (EW, free chlorine: 43 ± 6 ppm), lactic acid and phosphoric acid-based sanitizer (LPA, pH 2.89), or citric acid-based sanitizer (CA, pH 2.78) and soaked for 5 min. Two subsequent batches (eight non-inoculated heads per batch) were soaked in the same solution. Soaking with EW significantly reduced the population of S. enterica (2.8 ± 1.5 log CFU/g), E. coli O157:H7 (3.4 ± 1.1 log CFU/g), and L. monocytogenes (2.6 ± 0.7 log CFU/g) inoculated on Romaine lettuce compared to TW, LPA, and CA (p lettuce, EW significantly reduced populations of S. enterica and E. coli O157:H7, but not L. monocytogenes compared to other treatments. No significant difference was noted between TW, LPA, and CA in reducing foodborne pathogens (p > 0.05) or preventing cross-contamination. Soaking with EW prevented cross-contamination among lettuce heads and controlled bacterial populations in crisping water for three consecutive batches. EW may be an effective option as a sanitizer to minimizing the cross-contamination of leafy greens during the retail crisping. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Wild lettuce (Lactuca virosa) toxicity.

    Science.gov (United States)

    Besharat, Sima; Besharat, Mahsa; Jabbari, Ali

    2009-01-01

    Wild lettuce (Lactuca virosa) can cause toxic effects when eaten. Wild lettuce grows in the north of Iran and some natives consume it unaware of its adverse side effects. We describe eight patients with manifestations of wild lettuce toxicity, admitted to a general hospital affiliated to the Golestan University of Medical Sciences. All the patients recovered (although one had to spend 48 h in the intensive care unit) and no chronic complications were reported. A clinical suspicion of toxicity caused by wild lettuce intake and an accurate history formed the basis of the diagnosis. Conservative treatment, vital sign monitoring, control of patient intake and output, and reducing patient agitation provided the basis for treatment.

  18. Media Effects on Lettuce Growth in "Pillows" Designed for the VEGGIE Spaceflight Growth Chamber

    Science.gov (United States)

    Massa, Gioia; Newsham, Gerard; McCoy, LaShelle; Stutte, Gary; Wheeler, Raymond

    2012-01-01

    VEGGIE is a prototype vegetable production unit for space designed by Orbital Technologies Corporation that is being developed to fly on the International Space Station. A modular plant rooting system "pillow" is being designed to support plant growth in VEGGIE under microgravity conditions. VEGGIE pillows are small self-contained packets of media with time-release fertilizer that can wick water passively from a root mat reservoir. Seeds are planted in pillows and the entire root system of a plant is contained as the crop develops, preventing loss into the spacecraft cabin. This study compared five media types and three lettuce cultivars in pillows growing in a VEGGIE analog environment.. Media consisted of a peat-based potting mix (Fafard #2,Conrad Fafard Inc., Agawam, MA), and a calcined clay, (arcillite, 1-2 mm sifted, Turface Proleague, Profile LLC, Buffalo Grove IL) as well as three different blends of the two, 70:30, 50:50, and 30:70. Lettuce cultivars tested were 'Sierra', a bi-colored French crisp Batavia lettuce, 'Outredgeous', a red romaine lettuce and 'Flandria', a green butter head variety. Plants were grown for 28 days, harvested, biometric data was obtained, and tissue mineral analysis was performed. For all cultivars, lettuce plants grown in the media blends were more productive than those in the individual media types. All cultivars showed bell-shaped curves in response to increases in arcillite / decreases in Fafard #2 for leaf area, fresh, and dry mass. Plants in 100% Fafard #2 and in 100% arcillite were stunted, but only those in higher levels of Fafard #2 (70% and 100%) had reduced shoot percent moisture, possibly indicating that mechanisms causing stunting differed. Variation in tissue nutrient content are consistent with this, with Mg and Mn highest in plants grown in 100% Fafard and decreasing as the concentration of arcillite increased. Color also varied with media, especially in the 'Sierra' lettuce, with plants grown in increasing levels

  19. Detailed characterization of Mirafiori lettuce virus-resistant transgenic lettuce.

    Science.gov (United States)

    Kawazu, Yoichi; Fujiyama, Ryoi; Noguchi, Yuji; Kubota, Masaharu; Ito, Hidekazu; Fukuoka, Hiroyuki

    2010-04-01

    Lettuce big-vein disease is caused by Mirafiori lettuce virus (MiLV), which is vectored by the soil-borne fungus Olpidium brassicae. A MiLV-resistant transgenic lettuce line was developed through introducing inverted repeats of the MiLV coat protein (CP) gene. Here, a detailed characterization study of this lettuce line was conducted by comparing it with the parental, non-transformed 'Kaiser' cultivar. There were no significant differences between transgenic and non-transgenic lettuce in terms of pollen fertility, pollen dispersal, seed production, seed dispersal, dormancy, germination, growth of seedlings under low or high temperature, chromatographic patterns of leaf extracts, or effects of lettuce on the growth of broccoli or soil microflora. A significant difference in pollen size was noted, but the difference was small. The length of the cotyledons of the transgenic lettuce was shorter than that of 'Kaiser,' but there were no differences in other morphological characteristics. Agrobacterium tumefaciens used for the production of transgenic lettuce was not detected in transgenic seeds. The transgenic T(3), T(4), and T(5) generations showed higher resistance to MiLV and big-vein symptoms expression than the resistant 'Pacific' cultivar, indicating that high resistance to lettuce big-vein disease is stably inherited. PCR analysis showed that segregation of the CP gene was nearly 3:1 in the T(1) and T(2) generations, and that the transgenic T(3) generation was homozygous for the CP gene. Segregation of the neomycin phosphotransferase II (npt II) gene was about 3:1 in the T(1) generation, but the full length npt II gene was not detected in the T(2) or T(3) generation. The segregation pattern of the CP and npt II genes in the T(1) generation showed the expected 9:3:3:1 ratio. These results suggest that the fragment including the CP gene and that including the npt II gene have been integrated into two unlinked loci, and that the T(1) plant selected in our study did

  20. Romain Rolland, Stefan Zweig et l’Europe (1919-1933)

    OpenAIRE

    Brancy , Jean-Yves

    2005-01-01

    International audience; Romain Rolland (1866-1944), l’homme qui a tenté de fédérer les esprits européens contre la Barbarie de la guerre en 1914, fut un précurseur de l’idée européenne moderne. Dans chaque pays, des hommes ont agi dans une même communauté d’esprit pour tendre vers ce même objectif. Parmi ceux-ci, Stefan Zweig (1881-1942), entretint avec Romain Rolland une correspondance abondante où le thème européen figure en bonne place. Les deux écrivains évoquent l’idée d’une Europe cultu...

  1. La théorie de la diplomatie dans le Saint Empire Romain

    OpenAIRE

    Weber, Wolfgang E. J.

    2016-01-01

    Principes Dans ce que l’on nomme officiellement, depuis 1500 environ jusqu’à sa fin en 1806, le Saint Empire romain de la nation allemande (Heiliges Römisches Reich Deutscher Nation), le développement de la théorie de la diplomatie, autrement dit de conceptions relatives aux diplomates et à la diplomatie, est le fait d’élites soucieuses de mieux comprendre des problèmes posé...

  2. Moderate effect of damming the Romaine River (Quebec, Canada) on coastal plankton dynamics

    Science.gov (United States)

    Senneville, Simon; Schloss, Irene R.; St-Onge Drouin, Simon; Bélanger, Simon; Winkler, Gesche; Dumont, Dany; Johnston, Patricia; St-Onge, Isabelle

    2018-04-01

    Rivers' damming disrupts the seasonal cycle of freshwater and nutrient inputs into the marine system, which can lead to changes in coastal plankton dynamics. Here we use a 3-D 5-km resolution coupled biophysical model and downscale it to a 400-m resolution to simulate the effect of damming the Romaine River in Québec, Canada, which discharges on average 327 m3 s-1 of freshwater into the northern Gulf of St. Lawrence. Model results are compared with environmental data obtained from 2 buoys and in situ sampling near the Romaine River mouth during the 2013 spring-summer period. Noteworthy improvements are made to the light attenuation parametrization and the trophic links of the biogeochemical model. The modelled variables reproduced most of the observed levels of variability. Comparisons between natural and regulated discharge simulation show differences in primary production and in the dominance of plankton groups in the Romaine River plume. The maximum increase in primary production when averaged over the inner part of Mingan Archipelago is 41%, but 7.1% when the primary production anomaly is averaged from March to September.

  3. Evaluation of Lettuce Genotypes for Seed Thermotolerance

    Science.gov (United States)

    Thermoinhibition of lettuce (Lactuca sativa L.) seed germination is a common problem associated with lettuce production. Depending on lettuce cultivars, seed germination may be inhibited when temperatures exceed 28oC. The delay or inhibition of seed germination at high temperatures may reduce seedli...

  4. Growth and photosynthesis of lettuce

    NARCIS (Netherlands)

    Holsteijn, van H.M.C.

    1981-01-01

    Butterhead lettuce is an important glass-house crop in the poor light period in The Netherlands. Fundamental data about the influence of temperature, light and CO 2 on growth and photosynthesis are important e.g. to facilitate selection criteria for new cultivars. In

  5. Selenium accumulation in lettuce germplasm

    Science.gov (United States)

    Selenium (Se) is an essential micronutrient for animals and humans. Increasing Se content in food crops offers an effective approach to reduce the widespread selenium deficiency problem in many parts of the world. In this study, we evaluated thirty diverse accessions of lettuce (Lactuca sativa L.) f...

  6. Le cochon comme problème. Grecs, Romains et l’interdit juif du porc

    OpenAIRE

    Har - Peled, Misgav

    2012-01-01

    Composition du Jury : Monsieur Philippe Borgeaud (Université de Genève) ;Monsieur Daniel Boyarin (Université de Californie, Berkeley) ;Monsieur Maurice Kriegel (ÉHESS), directeur en cotutelle ;Monsieur David Nirenberg (Université de Chicago), directeur en cotutelle Monsieur Jean-Claude Schmitt (ÉHESS). Thèse soutenue le 28 novembre 2011 Résumé La thèse identifie pourquoi et comment l’interdit juif du porc est devenu l’interdit alimentaire juif par excellence dans le monde gréco-romain. Par un...

  7. LES CERFS-VOLANTS OU LA MÉMOIRE HISTORIQUE DE ROMAIN GARY

    OpenAIRE

    Barkate , Jonathan

    2016-01-01

    International audience; Dédié à la mémoire, le dernier roman de Romain Gary rend un vibrant hommage à la Résistance et doit être lu comme un testament destiné à perpétuer le souvenir de ceux qui ont contribué à surmonter la honte des années d’occupation. La galerie de portraits de résistants vante la folie sacrée et le roman met en scène un triangle amoureux en miroir de la situation politique de 1939-1945.

  8. A survey of syrphid predators of Nasonovia ribisnigri in organic lettuce on the central coast of California.

    Science.gov (United States)

    Smith, Hugh A; Chaney, William E

    2007-02-01

    Organic lettuce, Lactuca sativa L., producers on California's Central Coast rely on endemic syrphid flies (Diptera: Syrphidae) to suppress populations of Nasonovia ribisnigri Mosley (Homoptera: Aphididae) and other aphids affecting lettuce. Growers are using various forms of habitat manipulation to enhance biological control. We surveyed syrphids collected from organic romaine in and around the Salinas Valley from March through September 2005 to gain a better understanding of the species responsible for aphid suppression and to examine possible implications for biocontrol. The primary species of syrphid fly reared were Toxomerus marginatus (Say) (39%), Platycheirus stegnus (Say) (27%), Sphaerophoria sulfuripes (Thomson) (13%), and Allograpta obliqua (Say) (10%). Syrphus opinator Osten Sacken (2%), Toxomerus occidentalis (Curran) (1.3%), and Eupeodes volucris Osten Sacken (1%) were less common. Sphaerophoria pyrrhina Bigot, Scaeva pyrastri (L.), Platycheirus obscurus Say, Allograpta exotica Wiedemann, and Eupeodes americanus Wiedemann each made up aphids. P. stegnus was observed to deposit in clusters of eggs, and was only reared in significant numbers from highly infested fields. Approximately 5% of syrphid larvae overall were parasitized by either Diplazon sp. (Hymenoptera: Ichneumonidae) or Pachyneuron sp. (Hymenoptera: Pteromalidae).

  9. Potential internalisation of caliciviruses in lettuce.

    Science.gov (United States)

    Urbanucci, A; Myrmel, M; Berg, I; von Bonsdorff, C-H; Maunula, L

    2009-10-31

    Fresh produce such as lettuce (Lactuca sativa) has often been linked to epidemic viral gastroenteritis. In these cases, it is unknown whether the viral contamination has occurred during the growing or the processing of the implicated product. In this study lettuce was grown in the presence of enteric viruses, and the uptake of viruses via the roots into the edible parts (leaves and stem) of the lettuce plants was investigated, for plants with both intact and damaged roots. The roots of lettuce, growing either in hydroponic culture or in soil, were exposed to canine calicivirus (CaCV) and a human genogroup 2 norovirus (HuNoV) by these being added into the water or soil in which the lettuce was growing. Leaves from lettuce plants and seedlings were examined for viruses by real-time RT-PCR. When the lettuce plants were exposed to very high concentrations of CaCV, the virus was detected in lettuce leaves, indicating contamination via the roots, but the frequency of positive results was low. Internalisation occurred in both seedlings and grown plants, in both hydroponic and soil cultures, and occurred whether the roots were intact or damaged. However, internalisation of HuNoV was not detected in any of the experimental set ups, although the concentrations to which the plants were exposed were relatively high. Based on these results, viral contamination of lettuce plants via roots cannot be excluded, but is apparently not an important transmission route for viruses.

  10. Pochonia chlamydosporia promotes the growth of tomato and lettuce plants

    Directory of Open Access Journals (Sweden)

    Rosangela Dallemole-Giaretta

    2015-10-01

    Full Text Available The fungus Pochonia chlamydosporia is one of the most studied biological agents used to control plant-parasitic nematodes. This study found that the isolates Pc-3, Pc-10 and Pc-19 of this fungus promote the growth of tomato and lettuce seedlings. The isolate Pc-19 colonized the rhizoplane of tomato seedlings in only 15 days and produced a large quantity of chlamydospores. This isolate was able to use cellulose as a carbon source, in addition to glucose and sucrose. Scanning electron microscopy (SEM revealed that hyphae of the P. chlamydosporia isolate Pc-10 penetrated the epidermal cells of the tomato roots. These three P. chlamydosporia isolates promote the growth of tomato and lettuce.

  11. Genetics of resistance against lettuce downy mildew

    Science.gov (United States)

    Lettuce (Lactuca sativa) is one of the most valuable vegetable crops in the U.S. Downy mildew (DM), caused by Bremia lactucae, is the most important foliar disease of lettuce worldwide, which decreases the quality of the marketable portion of the crop. The use of resistant varieties carrying dominan...

  12. Comparative Study of Lettuce and Radish Grown Under Red and Blue LEDs and White Fluorescent Lamps

    Science.gov (United States)

    Mickens, Matthew A.; Massa, Gioia; Newsham, Gerard; Wheeler, Raymond; Birmele, Michele

    2016-01-01

    Growing vegetable crops in space will be an essential part of sustaining astronauts during long-range missions. To drive photosynthesis, red and blue light-emitting diodes (LEDs) have attracted attention because of their efficiency, longevity, small size, and safety. In efforts to optimize crop yield, there is also recent interest in analyzing the subtle effects of additional wavelengths on plant growth. For instance, since plants often look purplish gray under red and blue LEDs, the addition of green light allows easy recognition of disease and the assessment of plant health status. However, it is important to know if wavelengths outside the traditional red and blue wavebands have a direct effect on enhancing or hindering the mechanisms involved in plant growth. In this experiment, a comparative study was performed on two short cycle crops of red romaine lettuce (Lactuca sativa cv. "Outredgeous") and radish (Raphanus sativa cv. 'Cherry Bomb'), which were grown under two light treatments. The first treatment being red (630 nm) and blue (450 nm) LEDs alone, while the second treatment consisted of daylight tri-phosphor fluorescent lamps (CCT approximately 5000 K) at equal photosynthetic photon flux (PPF). The treatment effects were evaluated by measuring the fresh biomass produced, plant morphology and leaf dimensions, leaf chlorophyll content, and adenosine triphosphate (ATP) within plant leaf/storage root tissues.

  13. Resistance to lettuce aphid (Nasonovia ribisnigri) biotype 0 in wild lettuce accessions PI 491093 and PI 274378

    Science.gov (United States)

    Lettuce aphid, Nasonovia ribisnigri Mosley (Homoptera : Aphididae), is a major insect pest of lettuce, Lactuca sativa L, in many commercial lettuce productions areas around the world. Resistance to lettuce aphid was first reported in Lactuca virosa L. accession IVT 280 and characterized as complete,...

  14. Biological Control of Lettuce Drop and Host Plant Colonization by Rhizospheric and Endophytic Streptomycetes

    Science.gov (United States)

    Chen, Xiaoyulong; Pizzatti, Cristina; Bonaldi, Maria; Saracchi, Marco; Erlacher, Armin; Kunova, Andrea; Berg, Gabriele; Cortesi, Paolo

    2016-01-01

    Lettuce drop, caused by the soil borne pathogen Sclerotinia sclerotiorum, is one of the most common and serious diseases of lettuce worldwide. Increased concerns about the side effects of chemical pesticides have resulted in greater interest in developing biocontrol strategies against S. sclerotiorum. However, relatively little is known about the mechanisms of Streptomyces spp. as biological control agents against S. sclerotiorum on lettuce. Two Streptomyces isolates, S. exfoliatus FT05W and S. cyaneus ZEA17I, inhibit mycelial growth of Sclerotinia sclerotiorum by more than 75% in vitro. We evaluated their biocontrol activity against S. sclerotiorum in vivo, and compared them to Streptomyces lydicus WYEC 108, isolated from Actinovate®. When Streptomyces spp. (106 CFU/mL) were applied to S. sclerotiorum inoculated substrate in a growth chamber 1 week prior lettuce sowing, they significantly reduced the risk of lettuce drop disease, compared to the inoculated control. Interestingly, under field conditions, S. exfoliatus FT05W and S. cyaneus ZEA17I protected lettuce from drop by 40 and 10% respectively, whereas S. lydicus WYEC 108 did not show any protection. We further labeled S. exfoliatus FT05W and S. cyaneus ZEA17I with the enhanced GFP (EGFP) marker to investigate their rhizosphere competence and ability to colonize lettuce roots using confocal laser scanning microscopy (CLSM). The abundant colonization of young lettuce seedlings by both strains demonstrated Streptomyces' capability to interact with the host from early stages of seed germination and root development. Moreover, the two strains were detected also on 2-week-old roots, indicating their potential of long-term interactions with lettuce. Additionally, scanning electron microscopy (SEM) observations showed EGFP-S. exfoliatus FT05W endophytic colonization of lettuce root cortex tissues. Finally, we determined its viability and persistence in the rhizosphere and endorhiza up to 3 weeks by quantifying its

  15. Biological control of lettuce drop and host plant colonization by rhizospheric and endophytic streptomycetes

    Directory of Open Access Journals (Sweden)

    Xiaoyulong eChen

    2016-05-01

    Full Text Available Lettuce drop, caused by the soil borne pathogen Sclerotinia sclerotiorum, is one of the most common and serious diseases of lettuce worldwide. Increased concerns about the side effects of chemical pesticides have resulted in greater interest in developing biocontrol strategies against S. sclerotiorum. However, relatively little is known about the mechanisms of Streptomyces spp. as biological control agents against S. sclerotiorum on lettuce. Two Streptomyces isolates, S. exfoliatus FT05W and S. cyaneus ZEA17I, inhibit mycelial growth of Sclerotinia sclerotiorum by more than 75% in vitro. We evaluated their biocontrol activity against S. sclerotiorum in vivo, and compared them to Streptomyces lydicus WYEC 108, isolated from Actinovate®. When Streptomyces spp. (106 CFU/mL were applied to S. sclerotiorum inoculated substrate in a growth chamber one week prior lettuce sowing, they significantly reduced the risk of lettuce drop disease, compared to the inoculated control. Interestingly, under field conditions, S. exfoliatus FT05W and S. cyaneus ZEA17I protected lettuce from drop by 40% and 10% respectively, whereas S. lydicus WYEC 108 did not show any protection. We further labeled S. exfoliatus FT05W and S. cyaneus ZEA17I with the enhanced GFP (EGFP marker to investigate their rhizosphere competence and ability to colonize lettuce roots using confocal laser scanning microscopy (CLSM. The abundant colonization of young lettuce seedlings by both strains demonstrated Streptomyces’ capability to interact with the host from early stages of seed germination and root development. Moreover, the two strains were detected also on two-week-old roots, indicating their potential of long-term interactions with lettuce. Additionally, scanning electron microscopy (SEM observations showed EGFP-S. exfoliatus FT05W endophytic colonization of lettuce root cortex tissues. Finally, we determined its viability and persistence in the rhizosphere and endorhiza up to

  16. Precut prepackaged lettuce: a risk for listeriosis?

    Science.gov (United States)

    Hanning, Irene B; Johnson, Michael G; Ricke, Steven C

    2008-12-01

    The most recent outbreaks of listeriosis have been traced back to contaminated ready-to-eat (RTE) poultry and meat products. However, Listeria monocytogenes can be isolated from every food group, including fresh vegetables. This review is focused on one of the most popular RTE vegetable products, precut prepackaged lettuce. The available literature concerning Listeria contamination of vegetables is reviewed, and possible reasons why no recent outbreaks or sporadic cases of listeriosis due to contaminated precut prepackaged lettuce are explored.

  17. Influence of mycorrhizal fungi (glomus intraradices) on survival of Salmonella and E.coli 0157:H7 in soil and translocation into romaine lettuce roots and shoot

    Science.gov (United States)

    Modern agriculture practices disrupt the natural symbiotic relationship that arbuscular mycorrhizal (AM) fungi have with most vegetable plants, which may affect translocation of human pathogens into the plant and/or survival in the soil. AM-fungi are frequently utilized in organic farming to improv...

  18. Bacterial surface-displayed GII.4 human norovirus capsid proteins bound to surface of Romaine lettuce through HBGA-like molecules

    Science.gov (United States)

    Human Noroviruses (HuNoVs) are the main cause of nonbacterial gastroenteritis. Contaminated produce is a main vehicle for dissemination of HuNoVs. In this study, we used an ice nucleation protein (INP) mediated surface display system to present the protruding domain of GII.4 HuNoV capsid protein (G...

  19. Atmospheric cold plasma inactivation of Escherichia coli 0157:H7 and aerobic microorganisms in cold-stored romaine lettuce packaged in a commerical polyethylene terephthalate container

    Science.gov (United States)

    Leafy greens continue to be a significant vector for foodborne pathogens, including Escherichia coli O157:H7. Dielectric barrier discharge atmospheric cold plasma (ACP) treatment is a promising method for microbial decontamination of produce. An important aspect of this technology is the potential f...

  20. The presence of Spinoza in the exchanges between Sigmund Freud and Romain Rolland.

    Science.gov (United States)

    Vermorel, Henri

    2009-12-01

    Although Freud recognized his profound affinity with Spinoza, we seldom find explicit and direct references to the philosopher in his works. The correspondence between Romain Rolland, the 'Christian without a church', and Freud, the 'atheist Jew', is full of Spinozian reminiscences that nourish their works of this period and are underpinned by their mutual transference. The Future of an Illusion is written according to a Spinozian blueprint and aims at replacing religion, qualified as superstition, by psychoanalysis. A quotation from Heine, 'brother in unbelief', is a direct reference to Spinoza. Concurring with Freud's critiques of dogmas and churches, Rolland proposes an analysis of the 'oceanic feeling' as a basis of the religious sentiment. Freud replies with Civilization and Its Discontents. In 1936, on the occasion of Rolland's 70th birthday, Freud sends him an open letter, A disturbance of memory on the Acropolis, where the strange feeling that he has experienced in front of the Parthenon refers inter alia to his double culture: Jewish and German. In the light of this correspondence, the creation of psychoanalysis turns out to be a quest for the sacred that has disappeared in modernity; Freud, though, was able to find it inside man's unconscious.

  1. Advancements in utilizing molecular markers in lettuce breeding

    Science.gov (United States)

    Lettuce (Lactuca sativa L.) is globally the most popular commercially produced, leafy vegetable, farmed in moderate climates. Cultivated lettuce is a self-fertilizing, diploid (2n = 2x = 18) species from the family Compositae (Asteraceae). New cultivars of lettuce are developed by combining desirabl...

  2. Genetic characterization of resistance to Sclerotinia in lettuce cultivar Eruption

    Science.gov (United States)

    Lettuce drop caused by the fungal pathogens Sclerotinia minor and S. sclerotiorum is a serious disease of lettuce. The use of genetic resistance as part of an integrated lettuce drop management strategy should have a significant economic advantage in mitigating yield loss. Sclerotinia resistance is ...

  3. Development of marker-free transgenic lettuce resistant to Mirafiori lettuce big-vein virus.

    Science.gov (United States)

    Kawazu, Yoichi; Fujiyama, Ryoi; Imanishi, Shunsuke; Fukuoka, Hiroyuki; Yamaguchi, Hirotaka; Matsumoto, Satoru

    2016-10-01

    Lettuce big-vein disease caused by Mirafiori lettuce big-vein virus (MLBVV) is found in major lettuce production areas worldwide, but highly resistant cultivars have not yet been developed. To produce MLBVV-resistant marker-free transgenic lettuce that would have a transgene with a promoter and terminator of lettuce origin, we constructed a two T-DNA binary vector, in which the first T-DNA contained the selectable marker gene neomycin phosphotransferase II, and the second T-DNA contained the lettuce ubiquitin gene promoter and terminator and inverted repeats of the coat protein (CP) gene of MLBVV. This vector was introduced into lettuce cultivars 'Watson' and 'Fuyuhikari' by Agrobacterium tumefaciens-mediated transformation. Regenerated plants (T0 generation) that were CP gene-positive by PCR analysis were self-pollinated, and 312 T1 lines were analyzed for resistance to MLBVV. Virus-negative plants were checked for the CP gene and the marker gene, and nine lines were obtained which were marker-free and resistant to MLBVV. Southern blot analysis showed that three of the nine lines had two copies of the CP gene, whereas six lines had a single copy and were used for further analysis. Small interfering RNAs, which are indicative of RNA silencing, were detected in all six lines. MLBVV infection was inhibited in all six lines in resistance tests performed in a growth chamber and a greenhouse, resulting in a high degree of resistance to lettuce big-vein disease. Transgenic lettuce lines produced in this study could be used as resistant cultivars or parental lines for breeding.

  4. Genetic investigation of the nonhost resistance of wild lettuce, Lactuca saligna, to lettuce downy mildew, Bremia lactucae

    NARCIS (Netherlands)

    Boer, den E.

    2014-01-01

    Abstract

    Downy mildew (Bremia lactucae) in lettuce (Lactuca sativa) is a devastating foliar disease causing high losses in lettuce cultivation. The wild lettuce and nonhost species, Lactuca saligna, is absolute resistant to downy mildew and

  5. Sources of Verticillium dahliae affecting lettuce.

    Science.gov (United States)

    Atallah, Zahi K; Maruthachalam, Karunakaran; Subbarao, Krishna V

    2012-11-01

    ABSTRACT Since 1995, lettuce in coastal California, where more than half of the crop in North America is grown, has consistently suffered from severe outbreaks of Verticillium wilt. The disease is confined to this region, although the pathogen (Verticillium dahliae) and the host are present in other crop production regions in California. Migration of the pathogen with infested spinach seed was previously documented, but the geographic sources of the pathogen, as well as the impact of lettuce seed sparsely infested with V. dahliae produced outside coastal California on the pathogen population in coastal California remain unclear. Population analyses of V. dahliae were completed using 16 microsatellite markers on isolates from lettuce plants in coastal California, infested lettuce seed produced in the neighboring Santa Clara Valley of California, and spinach seed produced in four major spinach seed production regions: Chile, Denmark, the Netherlands, and the United States (Washington State). California produces 80% of spinach in the United States and all seed planted with the majority infested by V. dahliae comes from the above four sources. Three globally distributed genetic populations were identified, indicating sustained migration among these distinct geographic regions with multiple spinach crops produced each year and repeated every year in coastal California. The population structure of V. dahliae from coastal California lettuce plants was heavily influenced by migration from spinach seed imported from Denmark and Washington. Conversely, the sparsely infested lettuce seed had limited or no contribution to the Verticillium wilt epidemic in coastal California. The global trade in plant and seed material is likely contributing to sustained shifts in the population structure of V. dahliae, affecting the equilibrium of native populations, and likely affecting disease epidemiology.

  6. Stimulation of lettuce seed germination by ethylene.

    Science.gov (United States)

    Abeles, F B; Lonski, J

    1969-02-01

    Ethylene increased the germination of freshly imbibed lettuce (Lactuca sativa L. var. Grand Rapids) seeds. Seeds receiving either red or far-red light or darkness all showed a positive response to the gas. However, ethylene was apparently without effect on dormant seeds, those which failed to germinate after an initial red or far-red treatment. Carbon dioxide, which often acts as a competitive inhibitor of ethylene, failed to clearly reverse ethylene-enhanced seed germination. While light doubled ethylene production from the lettuce seeds, its effect was not mediated by the phytochrome system since both red and far-red light had a similar effect.

  7. Internalisation potential of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica subsp. enterica serovar Typhimurium and Staphylococcus aureus in lettuce seedlings and mature plants.

    Science.gov (United States)

    Standing, Taryn-Ann; du Plessis, Erika; Duvenage, Stacey; Korsten, Lise

    2013-06-01

    The internalisation potential of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella enterica subsp. enterica serovar Typhimurium in lettuce was evaluated using seedlings grown in vermiculite in seedling trays as well as hydroponically grown lettuce. Sterile distilled water was spiked with one of the four human pathogenic bacteria (10(5) CFU/mL) and used to irrigate the plants. The potential for pathogen internalisation was investigated over time using light microscopy, transmission electron microscopy and viable plate counts. Additionally, the identities of the pathogens isolated from internal lettuce plant tissues were confirmed using polymerase chain reaction with pathogen-specific oligonucleotides. Internalisation of each of the human pathogens was evident in both lettuce seedlings and hydroponically grown mature lettuce plants. To our knowledge, this is the first report of S. aureus internalisation in lettuce plants. In addition, the levels of background microflora in the lettuce plants were determined by plate counting and the isolates identified using matrix-assisted laser ionisation-time of flight (MALDI-TOF). Background microflora assessments confirmed the absence of the four pathogens evaluated in this study. A low titre of previously described endophytes and soil inhabitants, i.e., Enterobacter cloacae, Enterococcus faecalis, Lysinibacillus fusiformis, Rhodococcus rhodochrous, Staphylococcus epidermidis and Staphylococcus hominis were identified.

  8. Ladybugs and Lettuce Leaves. Teachers' Manual.

    Science.gov (United States)

    Barnes, Tracy; And Others

    This is a guide for use with "Ladybugs and Lettuce Leaves" activity cards which are activities for elementary school students (grades 4 to 6) focusing on gardening. It includes educational objectives for each topic as well as lists of vocabulary words, comments, questions for discussion, additional activities, and resources. An interdisciplinary…

  9. Sensory analysis of calcium-biofortified lettuce

    Science.gov (United States)

    Vegetables represent an attractive means of providing increased calcium nutrition to the public. In this study, it was demonstrated that lettuce expressing the deregulated Arabidopsis H(+)/Ca(2+) transporter sCAX1 (cation exchanger 1) contained 25-32% more calcium than controls. These biofortified l...

  10. Overexpression of homogentisate phytyltransferase in lettuce results ...

    African Journals Online (AJOL)

    In this study, HPT gene isolated from Lactuca sativa L. (LsHPT) was transferred into L. sativa (lettuce) via Agrobacterium-mediated method and 15 transgenic plants were obtained. The expression of LsHPT gene and the total content of and -tocopherol in transgenic plants were increased up to 4 and 2.61 folds, respectively, ...

  11. AND DEVELOPMENT OF LETTUCE ON CHERNOZEM ORDINARY

    Directory of Open Access Journals (Sweden)

    N. V. Gromakova

    2017-01-01

    Full Text Available Lettuce is very popular in the Russian consumer market. Special conditions for its cultivation determine the need to select modern, inexpensive elements of agro-technology that promote high yields. At present biochar (bio-coal is considered as a promising organic fertilizer. Its main difference lies in the possibility of using any organic raw material in its production. In Russia, the study on the use of biochar is limited; there is no practice of applying it in the complex of agricultural techniques of various agricultural crops. In the conditions of vegetative experiment, the influence of various doses of biochar in ordinary chernozem on the growth and development of lettuce (Lactuca sativa cultivar was studied in accordance with the developed experiment scheme: control (without biochar, supplemented with 1, 2 and 5 % of biochar. In the experiment, biochar obtained from birch wood was used, by pyrolysis method in fraction of 0.5-5mm. The following observations and determinations were made: the timing of the onset of the phases of plant development, the length of the roots, the number of leaves, the length of the largest leaf, the height of plants, the diameter of the rosette, the mass of 10 plants. The use of biochar contributed to a reduction of beginning period technical ripeness in plants, particularly in variant with the addition of 2%. The increase in root length, the number of leaves of lettuce plants as compared with to control in variants with 2 and 5% of biocar has been observed. The length of the largest leaf, the height of plants and the diameter of the rosette of lettuce are characterized by a significant improvement, even in variant with 1%. Productivity of lettuce was highest in the variant with 2% of biochar applied to the soil.

  12. Partial aphid resistance in lettuce negatively affects parasitoids.

    Science.gov (United States)

    Lanteigne, Marie-Eve; Brodeur, Jacques; Jenni, Sylvie; Boivin, Guy

    2014-10-01

    This study investigated the effects of partial plant resistance on the lettuce aphid Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae), a major pest of cultivated lettuce (Lactuca sativa L.), and one of its parasitoids, Aphidius ervi Haliday (Hymenoptera: Braconidae). Aphids were reared on susceptible (L. sativa variety Estival; S) or partially resistant (Lactuca serriola L. PI 491093; PR) lettuce, and next parasitized by A. ervi females. Fitness proxies were measured for both aphids and parasitoids. Developmental time to adult stage took longer for alate and apterous aphids (an average of 3.5 and 1.5 additional days, respectively) on PR than on S lettuce, and fecundity of alate aphids reared on PR lettuce was reduced by 37.8% relative to those reared on S lettuce. Size (tibia length) and weight of aphids reared on PR lettuce were lower than for aphids reared on S lettuce from the third and second instar onward, respectively. Parasitism of aphids reared on PR plants resulted in lower parasitoid offspring emergence (-49.9%), lower adult female (-30.3%) and male (-27.5%) weight, smaller adult female (-17.5%) and male (-11.9%) size, and lower female fecundity (37.8% fewer eggs) than when parasitoids developed from aphids reared on S plants. Our results demonstrate that partial aphid resistance in lettuce negatively affects both the second and third trophic levels. Host plant resistance in cultivated lettuce may therefore create an ecological sink for aphid parasitoids.

  13. Evaluation of sanitary quality of lettuce (Lactuca sativa, L. irrigated with reused water in comparison with commercialized lettuce

    Directory of Open Access Journals (Sweden)

    Claudinei Fonseca Souza

    2011-08-01

    Full Text Available Inadequate use of water resources reduces their availability and therefore, research focused on their reutilization is required. This work evaluated the sanitary quality of lettuce irrigated with reused water in comparison with samples of lettuce commercialized in Taubaté (SP market. An experiment was developed in a greenhouse with three beds of lettuce irrigated with reused water and three beds of lettuce irrigated with urban water supply. After lettuce biological cycle had been completed, lettuce samples were collected from the beds (irrigated and non-irrigated with reused water and from samples of lettuce commercialized in the city market that were analyzed in the laboratory. The analyses were done using the multiple tubes methodology. The results showed that the samples from lettuce irrigated with urban water supply were not contaminated by either total or thermotolerant coliforms while samples of irrigated lettuce with reused water were contaminated by total coliforms. Samples from commercialized lettuce were contaminated by both kinds of coliforms. Results indicated that the application of reused water for agricultural purposes should occur only after carefully treatment to allow a safe use and to contribute to the water use sustainability.

  14. Agronomic efficiency of intercropping tomato and lettuce

    Directory of Open Access Journals (Sweden)

    Arthur B. Cecílio Filho

    2011-09-01

    Full Text Available Four experiments were carried out at the São Paulo State University, Brazil, with the aim of determining the agronomic viability of intercropping tomato and lettuce, under greenhouse conditions. The studied intercropping systems were established by transplanting lettuce at 0, 10, 20 and 30 days after transplanting (DAT tomato and by transplanting tomato at 0, 10, 20 and 30 DAT lettuce. Intercropped tomato and lettuce were evaluated during two seasons and compared to their sole cropping. The experimental design was a randomized complete block with nine treatments. The productivity and the classification of the tomato fruits were not influenced by having lettuce intercropped with it, but lettuce production was lowered when tomato was intercropped with it. The longer the delay in lettuce transplanting, the greater the reduction in its productivity. There was an effect of cropping season on the extent of the agronomic advantage of intercropping over sole cropping. In the first cropping season, intercropping established by transplanting lettuce during the interval between 30 days before up to 20 DAT tomato yielded land use efficiency (LUE indices of 1.63 to 2.22. In the second period, intercropping established with the transplanting of lettuce up to 30 days before tomato yielded LUE indices of 1.57 to 2.05.Quatro experimentos foram conduzidos na Unesp, Brasil, com o objetivo de determinar a viabilidade agronômica de cultivos consorciados de alface e tomate em ambiente protegido. Consórcios estabelecidos por transplantes da alface aos 0, 10, 20 e 30 dias após o transplante (DAT do tomate e de tomate aos 0, 10, 20 e 30 DAT da alface, foram avaliados em duas épocas e comparados às suas monoculturas. Cada experimento foi conduzido em delineamento de blocos ao acaso, com nove tratamentos. Verificou-se que a produtividade do tomate e a classificação dos frutos não foram influenciadas pela alface, mas a produção da alface foi menor em cons

  15. Comparative Infection Progress Analysis of Lettuce big-vein virus and Mirafiori lettuce virus in Lettuce Crops by Developed Molecular Diagnosis Techniques.

    Science.gov (United States)

    Navarro, Jose A; Botella, Francisco; Maruhenda, Antonio; Sastre, Pedro; Sánchez-Pina, M Amelia; Pallas, Vicente

    2004-05-01

    ABSTRACT Nonisotopic molecular dot blot hybridization technique and multiplex reverse transcription-polymerase chain reaction assay for the specific detection of Lettuce big-vein virus (LBVV) and Mirafiori lettuce virus (MiLV) in lettuce tissue were developed. Both procedures were suitable for the specific detection of both viruses in a range of naturally infected lettuce plants from various Spanish production areas and seven different cultivars. The study of the distribution of both viruses in the plant revealed that the highest concentration of LBVV and MiLV occurred in roots and old leaves, respectively. LBVV infection progress in a lettuce production area was faster than that observed for MiLV. In spite of different rates of virus infection progress, most lettuce plants became infected with both viruses about 100 days posttransplant. The appearance of both viruses in lettuce crops was preceded by a peak in the concentration of resting spores and zoosporangia of the fungus vector Olpidium brassicae in lettuce roots.

  16. Effect of dim light irradiation on preservation of fresh lettuce

    International Nuclear Information System (INIS)

    Harada, F.; Uchino, T.; Akimoto, K.; Hu, W.

    2001-01-01

    In order to preserve fresh lettuce, the dim light irradiation storage was investigated. Lettuce (Lactuca sativa L.) stored for about 120 hours at 5 or 20 deg C under continuous illumination at 0 (darkness), 1.6, 3.4, 6.5, 13 or 19.7 micro mol/m**-2/s**-1 photosynthetic photon flux. The light compensation point was about 3.4 micro mol/m**-2/s**-1 at 5 deg C, about 19.7 micro mol/m**-2/s**-1 at 20 deg C. Fresh weight of lettuce decreased by promotion of transpiration caused by the dim light. Accordingly the root of lettuce should not be removed, so as to up-take water. The optimum dim light irradiation preserved the chlorophyll content in lettuce leaf or increased it. Therefore it appeared that the dim light irradiation was effective for the fresh lettuce preservation

  17. Evaluation of non-chemical seed treatment methods for the control of Phoma valerianellae on lamb`s lettuce seeds

    NARCIS (Netherlands)

    Schmitt, A.; Koch, E.; Stephan, D.; Kromphardt, C.; Jahn, M.; Krauthausen, H.J.; Forsberg, G.; Werner, S.; Amein, T.; Wright, S.A.I.; Tinivella, F.; Wolf, van der J.M.; Groot, S.P.C.

    2009-01-01

    The aim of the present study was to identify seed treatment methods for eradicating Phoma valerianellae from lamb`s lettuce seeds in organic vegetable production. Using seeds naturally infested with the pathogen, the effect of three physical methods (hot water, aerated steam, electron treatment) and

  18. Weedborne reservoirs and seed transmission of Verticillium dahliae in lettuce

    OpenAIRE

    Vallad, G E; Bhat, R G; Koike, S T; Ryder, E J; Subbarao, K V

    2005-01-01

    The seed transmission of Verticillium dahliae was evaluated in lettuce (Lactuca sativa). Seed collected from lettuce plants infected with V. dahliae were plated with or without surface sterilization on Sorenson's modified NP10 medium. Of the seed plated with or without surface sterilization, 90 and 66 %, respectively, yielded colonies of V. dahliae. The incidence of Verticillium wilt ranged from 55 to 80 % among lettuce plants grown from seed harvested from infected plants. All evaluated isol...

  19. Unravelling the resistance mechanism of lettuce against Nasonovia ribisnigri

    OpenAIRE

    Broeke, ten, C.J.M.

    2013-01-01

    Aphids are serious pests of crop plant species, and host plant resistance is often the most effective and environmentally friendly control strategy to control these pests. One of these aphid pests is the black currant - lettuce aphid, Nasonovia ribisnigri (Mosely), an economically important pest of cultivated lettuce, Lactuca sativa L. Host plant resistance has been used since 1982 to control this aphid species and is mediated by the Nr-gene, originating from wild lettuce Lactuca virosa L. H...

  20. Characterization of lettuce big-vein associated virus and Mirafiori lettuce big-vein virus infecting lettuce in Saudi Arabia.

    Science.gov (United States)

    Umar, M; Amer, M A; Al-Saleh, M A; Al-Shahwan, I M; Shakeel, M T; Zakri, A M; Katis, N I

    2017-07-01

    During 2014 and 2015, 97 lettuce plants that showed big-vein-disease-like symptoms and seven weed plants were collected from the Riyadh region. DAS-ELISA revealed that 25% and 9% of the lettuce plants were singly infected with LBVaV and MiLBVV, respectively, whereas 63% had a mixed infection with both viruses. The results were confirmed by multiplex reverse transcription polymerase chain reaction using primers specific for LBVaV and MiLBVV. LBVaV and MiLBVV were also detected in Sonchus oleraceus and Eruca sativa, respectively. The nucleotide sequence of LBVaV and MiLBVV Saudi isolates ranged from 94.3-100%, and their similarities to isolates with sequences in the GenBank database ranged from 93.9 to 99.6% and 93.8 to 99.3%, respectively. Olpidium sp. was present in the roots of lettuce plants with big-vein disease and it was shown to facilitate transmission of both viruses.

  1. Le sauvetage des juifs au Chambon-sur-Lignon à travers Les Cerfs-volants de Romain Gary

    OpenAIRE

    Letourneau, Ingrid

    2018-01-01

    Dans Les Cerfs-volants (1980) Romain Gary relate la jeunesse résistante de Ludo à Cléry, un village normand inventé par l'auteur. Au sein de cette fiction, Gary, lui‑même ancien résistant aux racines juives, cite à plusieurs reprises le nom du Chambon‑sur‑Lignon, village connu pour avoir sauvé des réfugiés juifs durant la Seconde Guerre mondiale. L'hommage de Gary adopte ainsi le ton de la pudeur. Surtout, la mémoire du village se déploie à travers le personnage d'Ambroise Fleury, dont certai...

  2. Sandra Boehringer, L'Homosexualité féminine dans l'Antiquité grecque et romaine

    Directory of Open Access Journals (Sweden)

    Rostom Mesli

    2008-07-01

    Full Text Available La publication de L’Homosexualité féminine dans l’Antiquité grecque et romaine de Sandra Boehringer est, à plusieurs titres, une excellente nouvelle.Sur le plan universitaire et éditorial, d’abord, ce livre vient confirmer qu’après de longues années de chape de plomb, les départements de lettres classiques et d’histoire ancienne sont en train de s’ouvrir aux recherches sur la sexualité. L’université française ne s’est mise – c’est le moins que l’on puisse dire – que très lentement aux recherc...

  3. Growing patterns to produce 'nitrate-free' lettuce (Lactuca sativa).

    Science.gov (United States)

    Croitoru, Mircea Dumitru; Muntean, Daniela-Lucia; Fülöp, Ibolya; Modroiu, Adriana

    2015-01-01

    Vegetables can contain significant amounts of nitrate and, therefore, may pose health hazards to consumers by exceeding the accepted daily intake for nitrate. Different hydroponic growing patterns were examined in this work in order to obtain 'nitrate-free lettuces'. Growing lettuces on low nitrate content nutrient solution resulted in a significant decrease in lettuces' nitrate concentrations (1741 versus 39 mg kg(-1)), however the beneficial effect was cancelled out by an increase in the ambient temperature. Nitrate replacement with ammonium was associated with an important decrease of the lettuces' nitrate concentration (from 1896 to 14 mg kg(-1)) and survival rate. An economically feasible method to reduce nitrate concentrations was the removal of all inorganic nitrogen from the nutrient solution before the exponential growth phase. This method led to lettuces almost devoid of nitrate (10 mg kg(-1)). The dried mass and calcinated mass of lettuces, used as markers of lettuces' quality, were not influenced by this treatment, but a small reduction (18%, p < 0.05) in the fresh mass was recorded. The concentrations of nitrite in the lettuces and their modifications are also discussed in the paper. It is possible to obtain 'nitrate-free' lettuces in an economically feasible way.

  4. Virus diseases in lettuce in the Mediterranean basin.

    Science.gov (United States)

    Moreno, Aranzazu; Fereres, Alberto

    2012-01-01

    Lettuce is frequently attacked by several viruses causing disease epidemics and considerable yield losses along the Mediterranean basin. Aphids are key pests and the major vectors of plant viruses in lettuce fields. Lettuce mosaic virus (LMV) is probably the most important because it is seed-transmitted in addition to be transmissible by many aphid species that alight on the crop. Tomato spotted wilt virus (TSWV) is another virus that causes severe damage since the introduction of its major vector, the thrips Frankliniella occidentalis. In regions with heavy and humid soils, Lettuce Mirafiori big-vein virus (LMBVV) can also produce major yield losses. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Varietal response to lead by lettuce

    Energy Technology Data Exchange (ETDEWEB)

    John, M.K.

    1977-06-01

    Nine lettuce varieties were hydroponically grown at six substrate Pb concentrations to 50 ppM in substrate. Top and root tissue Pb concentration, amounts assimilated, and translocation to edible tissue were dependent on the variety as well as substrate lead and exposure duration. Even though Pb in substrate was in a precipitated form, lettuce plants could assimilate and translocate Pb. Differential response of varieties with similar morphology indicated genetical regulated physiological mechanisms of Pb assimilation and translocation. This evidence suggests varietal selection could minimize human and animal dietary intake of Pb via food plants. While early growth of some varieties was stimulated by low concentrations of Pb, and high solution concentrations suppressed growth of several varieties, genetic variation also included non-significant response of growth.

  6. Lettuce seeds production in hydroponic system

    OpenAIRE

    Menezes, Nilson Lemos de; Santos, Osmar Souza dos; Schmidt, Denise

    2001-01-01

    Sementes de alface das cultivares Deyse e Regina foram produzidas em estufa, no sistema hidropônico, com elevados rendimentos por planta e boa qualidade de sementes, quando comparados a resultados de sistema convencional, de canteiros em campo. Esses dados sugerem estudos de produção de sementes de alface em cultivo protegido.Lettuce seeds of Deyse and Regina cultivars were produced in greenhouse, in hydroponic system, with excelents rendiments per plant and seed quality, when compared to con...

  7. USE OF PELLETED LETTUCE SEEDS IN BIOAVAILABILITY STUDIES

    Science.gov (United States)

    Lettuce (Latuca sativa L., cv. Buttercrunch) is one of the most common and sensitive test organisms, among plants, used in toxicology and bioavailability studies. Much of the available lettuce seeds in commercial channels are pelleted to allow for precision machine planting. Th...

  8. USE OF PELLETED LETTUCE SEEDS IN BIOABAILABILITY STUDIES

    Science.gov (United States)

    Lettuce (Latuca sativa L., cv. Buttercrunch) is one of the most common and sensitive test organisms, among plants, used in toxicology and bioavailability studies. Much of the available lettuce seeds in commercial channels are pelleted to allow for precision machine planting. Th...

  9. Marker-assisted selection for disease resistance in lettuce

    Science.gov (United States)

    Lettuce (Lactuca sativa L.) is the most popular leafy vegetable that is cultivated mainly in moderate climate. Consumers demand lettuce with good visual appearance and free of disease. Improved disease resistance of new cultivars is achieved by combining desirable genes (or alleles) from existing cu...

  10. 7 CFR 319.56-24 - Lettuce and peppers from Israel.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Lettuce and peppers from Israel. 319.56-24 Section 319... Lettuce and peppers from Israel. (a) Lettuce may be imported into the United States from Israel without... protected with sticky traps and prophylactic sprays approved for the crop by Israel; (v) The lettuce must be...

  11. Nutritional value, bioactive compounds, and health benefits of lettuce (Lactuca sativa L.)

    Science.gov (United States)

    Lettuce is one of the most popularly consumed vegetables worldwide but its nutritional value has been underestimated. Lettuce is low in calories and fat but high in fiber. Moreover, lettuce is high in potassium but low in sodium. Lettuce is also a good source of health-beneficial bioactive compounds...

  12. Microbiological quality and safety assessment of lettuce production in Brazil.

    Science.gov (United States)

    Ceuppens, Siele; Hessel, Claudia Titze; de Quadros Rodrigues, Rochele; Bartz, Sabrina; Tondo, Eduardo César; Uyttendaele, Mieke

    2014-07-02

    The microbiological quality and safety of lettuce during primary production in Brazil were determined by enumeration of hygiene indicators Escherichia coli, coliforms and enterococci and detection of enteric pathogens Salmonella and E. coli O157:H7 in organic fertilizers, soil, irrigation water, lettuce crops, harvest boxes and worker's hands taken from six different lettuce farms throughout the crop growth cycle. Generic E. coli was a suitable indicator for the presence of Salmonella and E. coli O157:H7, while coliforms and enterococci were not. Few pathogens were detected: 5 salmonellae and 2 E. coli O157:H7 from 260 samples, of which only one was lettuce and the others were manure, soil and water. Most (5/7) pathogens were isolated from the same farm and all were from organic production. Statistical analysis revealed the following environmental and agro-technical risk factors for increased microbial load and pathogen prevalence in lettuce production: high temperature, flooding of lettuce fields, application of contaminated organic fertilizer, irrigation with water of inferior quality and large distances between the field and toilets. Control of the composting process of organic fertilizers and the irrigation water quality appear most crucial to improve and/or maintain the microbiological quality and safety during the primary production of lettuce. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Littérature et éducation : le processus formatif du Fakir de Romain Puértolas

    Directory of Open Access Journals (Sweden)

    Artur Ribeiro Gonçalves

    2015-12-01

    Full Text Available L’extraordinaire voyage du Fakir qui est resté coincé dans une armoire Ikea, de Romain Puértolas, met en scène un fakir indien en quête d’un lit à clous à Paris.Prétexte pour un voyage à travers les difficultés de la contemporanéité, les heurs et malheurs du Fakir, héros picaresque, pendant son voyage, amusent et instruisent.Cet article propose de lire l’œuvre dans le cadre défini par le roman picaresque et d’en proposer la lecture à des étudiants non spécialistes en littérature, visant des objectifs d’éducation littéraire tout autant que des objectifs d’éducation par lalittérature (linguistiques, discursifs, esthétiques, d’analyse sociale. Le parcours formatif, par l’agencement des activités de réception, interaction et production, favorise la réflexion et la transformation du lecteur et s’inscrit dans la continuité du principe classique – amuser et instruire.

  14. Evidence for Lettuce big-vein associated virus as the causal agent of a syndrome of necrotic rings and spots in lettuce

    NARCIS (Netherlands)

    Verbeek, M.; Dullemans, A.M.; Bekkum, van P.J.; Vlugt, van der R.A.A.

    2013-01-01

    Lettuce big-vein associated virus (LBVaV, genus Varicosavirus) was shown to be responsible for characteristic necrotic symptoms observed in combination with big-vein symptoms in lettuce breeding lines when tested for their susceptibility to lettuce big-vein disease (BVD) using viruliferous Olpidium

  15. Genetic resources collections of leafy vegetables (lettuce, spinach, chicory, artichoke, asparagus, lamb’s lettuce, rhubarb and rocket salad): composition and gaps

    NARCIS (Netherlands)

    Treuren, van R.; Coquin, P.; Lohwasser, U.

    2012-01-01

    Lettuce, spinach and chicory are generally considered the main leafy vegetables, while a fourth group denoted by ‘minor leafy vegetables’ includes, amongst others, rocket salad, lamb’s lettuce, asparagus, artichoke and rhubarb. Except in the case of lettuce, central crop databases of leafy

  16. Effect of population density of lettuce intercropped with rocket on productivity and land-use efficiency

    Science.gov (United States)

    2018-01-01

    The objective of this study was to evaluate the influence of the spacing of lettuce rows on the production of a lettuce-rocket intercropping system over two growing seasons (11 August to 25 September 2011 and 12 January to 24 February 2012) in Jaboticabal, São Paulo, Brazil. We evaluated 11 treatments in each season: lettuce-rocket intercrops with five row spacings for the lettuce (0.20, 0.25, 0.30, 0.35 and 0.40 m) and the rocket planted midway between the lettuce rows, sole crops of lettuce at the same five row spacings and a sole crop of rocket. Fresh and dry masses of the lettuce and rocket and number of lettuce leaves per plant were highest with a lettuce row spacing of 0.40 m, but the productivities of the lettuce and rocket were higher with a lettuce row spacing of 0.20 m. The productivities and fresh and dry weights of the lettuce and rocket and the number of lettuce leaves per plant were highest in the sole crops, but the fresh and dry weights of the rocket were higher with intercropping. The land equivalent ratios were >1.0 in both seasons in all intercrops and were highest for the densest crop (1.41). Intercropping was therefore 41% more efficient than sole cropping for the production of lettuce and rocket. PMID:29698401

  17. Irrigation and nitrogen level affect lettuce yield in greenhouse ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-12-17

    Dec 17, 2008 ... and it achieves very high irrigation efficiency and uses. *Corresponding ... serious harmful effect on lettuce growing (Table 1). During the ... Seeds were sown in a seed bed under greenhouse conditions on. October 20th in ...

  18. Persistence of 14C maneb in lettuce plants an soil

    International Nuclear Information System (INIS)

    Bennaceur, M.; Sennaoui, Z.; Meguenni, H.

    1992-10-01

    Maneb residue is studied on lettuce plant and soil after spraying on greenhouse with 14C maneb. The residues declined with time. After 37 days from the application, 14C maneb residues in water extracts declined to 1,5. 10-2ug/g from 5,8. 10-1ug/g of the zero day sample in lettuce plants and 4,6. 10-3ug/g from 1,73. 10-1ug/g in soil. The 14C internals residues in lettuce and soil increase respectively till 16 days and 24 days, then decrease to 88% and 4,05% after 37 days. ETU was present in lettuce plant after 8 days then decreases with time. Two metabolites were identified by TLC (EU,ETU)

  19. The Inlfuence of Biochar on Growth of Lettuce and Potato

    Institute of Scientific and Technical Information of China (English)

    Kalika P. Upadhyay; Doug George; Roger S. Swift; Victor Galea

    2014-01-01

    Pot experiments were conducted in a glasshouse to determine the growth pattern of lettuce, true potato seedlings (TPS) and single node cuttings of TPS in response to biochar. The treatments were arranged in a randomized complete block design with 5 treatments (0, 10, 30, 50 and 100 t ha-1) of biochar from greenwaste with 5 replications in lettuce, 10 in TPS and 5 in single node cuttings of TPS. The observations recorded on growth parameters showed that biochar had signiifcant effect on growth of lettuce but no consistent effect on growth of TPS and single node cuttings. Among the biochar rates, 30 t ha-1 had the greatest inlfuence on overall growth of lettuce. The pH and electrical conductivity increased as the biochar rates increased in all experiments. These results provide an avenue for soil management system by using biochar as an amendment in horticultural crops. However, their veriifcation in the ifeld is important for speciifc recommendations.

  20. Lettuce achene invigoration through osmopriming at supraoptimal temperature

    International Nuclear Information System (INIS)

    Jahangir, M.M.; Amjad, M.; Iqbal, Q.; Nawaz, A.; Afzal, I.

    2009-01-01

    The effect of osmopriming on lettuce achene invigoration at supra optimal temperature (35degreeC) was investigated in the present study. Osmopriming of lettuce achene with KNO/sub 3/ (0.25%, 0.5% and 1%), CaCl/sub 2/ (15 mM, 25 mM, 50 mM) and PEG 8000 (0.1 g/ml H/sub 2/O, 0.2 g/ml H/sub 2/O, 0.3g/ml H/sub 2/O) alleviated thermodormancy and improved lettuce achene's vigor. Moreover, priming significantly improved final germination % age, energy of germination, germination index, shoot length, root length, vigor index and reduced mean germination time and time taken to 50% germination, as compared to control, when seeds were subjected to supra-optimal germination environments. It can be concluded that osmopriming can act as effective tool to invigorate lettuce seeds at supra optimal temperature. (author)

  1. A model for multiseasonal spread of verticillium wilt of lettuce.

    Science.gov (United States)

    Wu, B M; Subbarao, K V

    2014-09-01

    Verticillium wilt, caused by Verticillium dahliae, is a destructive disease in lettuce, and the pathogen is seedborne. Even though maximum seed infestation rates of lettuce seed lots, it is necessary to establish acceptable contamination thresholds to prevent introduction and establishment of the pathogen in lettuce production fields. However, introduction of inoculum into lettuce fields for experimental purposes to determine its long term effects is undesirable. Therefore, we constructed a simulation model to study the spread of Verticillium wilt following pathogen introduction from seed. The model consists of four components: the first for simulating infection of host plants, the second for simulating reproduction of microsclerotia on diseased plants, the third for simulating the survival of microsclerotia, and the fourth for simulating the dispersal of microsclerotia. The simulation results demonstrated that the inoculum density-disease incidence curve parameters and the dispersal gradients affect disease spread in the field. Although a steep dispersal gradient facilitated the establishment of the disease in a new field with a low inoculum density, a long-tail gradient allowed microsclerotia to be dispersed over greater distances, promoting the disease spread in fields with high inoculum density. The simulation results also revealed the importance of avoiding successive lettuce crops in the same field, reducing survival rate of microsclerotia between crops, and the need for breeding resistance against V. dahliae in lettuce cultivars to lower the number of microsclerotia formed on each diseased plant. The simulation results, however, suggested that, even with a low seed infestation rate, the pathogen would eventually become established if susceptible lettuce cultivars were grown consecutively in the same field for many years. A threshold for seed infestation can be established only when two of the three drivers of the disease-(i) low microsclerotia production per

  2. Silencing the lettuce homologs of small rubber particle protein does not influence natural rubber biosynthesis in lettuce (Lactuca sativa).

    Science.gov (United States)

    Chakrabarty, Romit; Qu, Yang; Ro, Dae-Kyun

    2015-05-01

    Natural rubber, cis-1,4-polyisoprene, is an important raw material in chemical industries, but its biosynthetic mechanism remains elusive. Natural rubber is known to be synthesized in rubber particles suspended in laticifer cells in the Brazilian rubber tree (Hevea brasiliensis). In the rubber tree, rubber elongation factor (REF) and its homolog, small rubber particle protein (SRPP), were found to be the most abundant proteins in rubber particles, and they have been implicated in natural rubber biosynthesis. As lettuce (Lactuca sativa) can synthesize natural rubber, we utilized this annual, transformable plant to examine in planta roles of the lettuce REF/SRPP homologs by RNA interference. Among eight lettuce REF/SRPP homologs identified, transcripts of two genes (LsSRPP4 and LsSRPP8) accounted for more than 90% of total transcripts of REF/SRPP homologs in lettuce latex. LsSRPP4 displays a typical primary protein sequence as other REF/SRPP, while LsSRPP8 is twice as long as LsSRPP4. These two major LsSRPP transcripts were individually and simultaneously silenced by RNA interference, and relative abundance, polymer molecular weight, and polydispersity of natural rubber were analyzed from the LsSRPP4- and LsSRPP8-silenced transgenic lettuce. Despite previous data suggesting the implications of REF/SRPP in natural rubber biosynthesis, qualitative and quantitative alterations of natural rubber could not be observed in transgenic lettuce lines. It is concluded that lettuce REF/SRPP homologs are not critically important proteins in natural rubber biosynthesis in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Irradiation of lettuce (Lactuca sativa. L.): microbiological and sensory aspects

    International Nuclear Information System (INIS)

    Tsuhako, Vanessa Provenzano

    2005-01-01

    The increasing demand for fresh foods have stimulated the marketing of minimally processed vegetables. However, these products maintain most of their natural microbiota even after being sanitized, including pathogenic microorganisms. Refrigerated storage allows the growth of psychotropic microorganisms and among them the pathogen Listeria monocytogenes. The ingestion of food contaminated with L. monocytogenes may represent a risk to pregnant women and their fetuses and to immunocompromised people. Non-thermal alternative processes for food preservation, such as irradiation, can reduce pathogenic and spoilage microorganism populations without impairing substantial changes in sensory, physical or chemical attributes. The aims of this research were to evaluate the effect of gamma radiation on L. monocytogenes artificially inoculated on minimally processed lettuce, to evaluate its effect on lettuce leaves through acceptance sensory test and to determine the irradiated vegetable shelf life through sensory and microbiological tests. A mixture of 4 types of lettuce (Iceberg, Boston, Loose-leaf and Red loose-leaf) were artificially inoculated with L. monocytogenes (7 log UFC/g lettuce) and then exposed to 0.3; 0.6; 0.9 and 1.2 kGy, under refrigeration. The DlO values for L. monocytogenes varied fram 0.18 to 0.21 kGy. Sensory and microbiological tests indicated that the shelf life of Iceberg lettuce stored at 7 deg C was 5 and 7 days for the irradiated and non-irradiated samples, respectively, and for the irradiated and non-irradiated Loose-leaf lettuce samples were 10 days. For the non-irradiated Boston sample, the shelf life was 3 days and for the Irradiated 7 days. Red loose-leaf showed 5 and 4 days of shelf lives for the irradiated and non-irradiated, respectively. Irradiated samples presented better microbiological quality than non-irradiated ones. The irradiation is feasible process to improve quality and safety of lettuce leaves. (author)

  4. Influence of production time on quality and height of yield of crisp lettuce

    International Nuclear Information System (INIS)

    Odziemkowski, S.; Gajc-Wolska, J.; Skapski, H.

    1998-01-01

    The cultivar of crisp lettuce Saladin, was grown in the field in 10 production terms starting from spring to autumn in 1993-95. The highest average weight of head of crisp lettuce was obtained in earlier terms of production. The head weight at the time of harvest depended on the amount of solar radiation during the time of lettuce head formation

  5. Genome-wide association study for lettuce cultivars with improved salad processing efficiency

    Science.gov (United States)

    Lettuce (Lactuca sativa L.) is widely used as the main ingredient of packaged leafy vegetable salads. Salad lettuce can have short shelf life, decaying as early as eight days after harvest and reducing the nutritional quality. Decayed lettuce is not marketable, produces extra waste, and results in t...

  6. Detection of Lettuce Discoloration Using Hyperspectral Reflectance Imaging.

    Science.gov (United States)

    Mo, Changyeun; Kim, Giyoung; Lim, Jongguk; Kim, Moon S; Cho, Hyunjeong; Cho, Byoung-Kwan

    2015-11-20

    Rapid visible/near-infrared (VNIR) hyperspectral imaging methods, employing both a single waveband algorithm and multi-spectral algorithms, were developed in order to discrimination between sound and discolored lettuce. Reflectance spectra for sound and discolored lettuce surfaces were extracted from hyperspectral reflectance images obtained in the 400-1000 nm wavelength range. The optimal wavebands for discriminating between discolored and sound lettuce surfaces were determined using one-way analysis of variance. Multi-spectral imaging algorithms developed using ratio and subtraction functions resulted in enhanced classification accuracy of above 99.9% for discolored and sound areas on both adaxial and abaxial lettuce surfaces. Ratio imaging (RI) and subtraction imaging (SI) algorithms at wavelengths of 552/701 nm and 557-701 nm, respectively, exhibited better classification performances compared to results obtained for all possible two-waveband combinations. These results suggest that hyperspectral reflectance imaging techniques can potentially be used to discriminate between discolored and sound fresh-cut lettuce.

  7. Selectivity of thiobencarb between two lettuce (Lactuca sativa, L.) cultivars

    International Nuclear Information System (INIS)

    Reiners, S.

    1987-01-01

    Thiobencarb [S-(4-chlorobenzyl)N,N-diethylthiocarbamate] was examined for weed control on muck grown lettuce. Weed control results were erratic though differential lettuce tolerance was observed in the field. This led to the testing of five lettuce cultivars for tolerance to the herbicide. Of the five lettuce cultivars evaluated, two were selected with the widest tolerance differences: Great Lakes 366 (GLA) (tolerant) and Dark Green Boston (BOS) (susceptible). Studies examining the mechanism of thiobencarb tolerance were conducted with these two cultivars. Within four days after the addition of thiobencarb to the nutrient solution, BOS had significant reductions in the foliar dry weight. In addition, growth abnormalities including fused leaves were observed, indicating inhibition early in leaf development. Greater amounts of 14 C-thiobencarb were absorbed from nutrient solution by BOS, likely due to a significantly greater root system at the time of treatment. The greater uptake and accumulation of 14 C-label in the leaves, as well as significantly greater amounts of unmetabolized 14 C-thiobencarb in the foliage of BOS may account for the selectivity observed. A thiobencarb sulfoxide was not identified in these studies. This indicates that the metabolism of thiobencarb in lettuce differs from other members of the thiocarbamate family of herbicides

  8. Lettuce flavonoids screening and phenotyping by chlorophyll fluorescence excitation ratio.

    Science.gov (United States)

    Zivcak, Marek; Brückova, Klaudia; Sytar, Oksana; Brestic, Marian; Olsovska, Katarina; Allakhverdiev, Suleyman I

    2017-06-01

    Environmentally induced variation and the genotypic differences in flavonoid and phenolic content in lettuce can be reliably detected using the appropriate parameters derived from the records of rapid non-invasive fluorescence technique. The chlorophyll fluorescence excitation ratio method was designed as a rapid and non-invasive tool to estimate the content of UV-absorbing phenolic compounds in plants. Using this technique, we have assessed the dynamics of accumulation of flavonoids related to developmental changes and environmental effects. Moreover, we have tested appropriateness of the method to identify the genotypic differences and fluctuations in total phenolics and flavonoid content in lettuce. Six green and two red genotypes of lettuce (Lactuca sativa L.) grown in pots were exposed to two different environments for 50 days: direct sunlight (UV-exposed) and greenhouse conditions (low UV). The indices based on the measurements of chlorophyll fluorescence after red, green and UV excitation indicated increase of the content of UV-absorbing compounds and anthocyanins in the epidermis of lettuce leaves. In similar, the biochemical analyses performed at the end of the experiment confirmed significantly higher total phenolic and flavonoid content in lettuce plants exposed to direct sun compared to greenhouse conditions and in red compared to green genotypes. As the correlation between the standard fluorescence indices and the biochemical records was negatively influenced by the presence of red genotypes, we proposed the use of a new parameter named Modified Flavonoid Index (MFI) taking into an account both absorbance changes due to flavonol and anthocyanin content, for which the correlation with flavonoid and phenolic content was relatively good. Thus, our results confirmed that the fluorescence excitation ratio method is useful for identifying the major differences in phenolic and flavonoid content in lettuce plants and it can be used for high-throughput pre

  9. Growth experiment in lettuce [Lactuca sativa] using laser light

    International Nuclear Information System (INIS)

    Mori, Y.; Takatsuji, M.

    2001-01-01

    Photosynthetic rate, relative growth rate and vitamin C contents were measured in lettuce cultivated under red and blue lasers and the results were compared with those cultivated under light emitting diodes (LED). It was found that lettuce grew fairly healthily under red laser diode (650 nm) and blue laser (442 nm) with R/B ratio 10. However, both photosynthetic rate and growth rate rather diminished compared with LED cases. As for vitamin C contents, the result was about the same as LED cases

  10. Phosphorus rates on yield and quality of lettuce seeds

    OpenAIRE

    Kano,Cristiaini; Cardoso,Antonio Ismael Inácio; Bôas,Roberto L Villas

    2012-01-01

    Because of lack of information about phosphorus fertilization in lettuce from the standpoint of seed production, this study was undertaken. The work was carried out in Botucatu, São Paulo state, Brazil, from September 25, 2003 to February 19, 2004, in order to study the influence of crescents phosphorus rates on yield and quality of lettuce seeds, cultivar Verônica. The experimental design was randomized blocks with five treatments (0; 200; 400; 600 and 800 kg ha-1 of P2O5) and five replicati...

  11. Activity of aphids associated with lettuce and broccoli in Spain and their efficiency as vectors of Lettuce mosaic virus.

    Science.gov (United States)

    Nebreda, M; Moreno, A; Pérez, N; Palacios, I; Seco-Fernández, V; Fereres, A

    2004-03-01

    This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed.

  12. Prevalence of Lettuce mosaic virus - common strain on three lettuce producing areas from São Paulo State

    OpenAIRE

    Firmino,Ana Carolina; Krause-Sakate,Renate; Pavan,Marcelo Agenor; Silva,Norberto da; Hanai,Sérgio Minoru; Anbo,Roberto Hiroto; Nietzsche,Thomas; Le Gall,Olivier

    2008-01-01

    LMV is one of the most important pathogens of lettuce worldwide. Based on their ability to overcome the resistance genes mo1¹ and mo1² in lettuce, isolates can be divided in two types: LMV-Most, which can infect and are seed-borne in cultivars containing the mo1 gene and LMV-Common, which do not cause symptoms on these cultivars and are seed transmitted only in susceptible cultivars. To evaluate the occurrence of these two types of LMV isolates, a survey was carried out during 2002-2005 in th...

  13. Uptake kinetics of arsenic by lettuce cultivars under hydroponics ...

    African Journals Online (AJOL)

    Arsenic (As) uptake ability based on kinetic parameters by two lettuce cultivars; Sijibaiye (SJBY) and Texuanyanlingsun (TXYLS) was investigated in nutrient solution containing eight levels of arsenic (As). Depletion of As from solution was monitored over a period of 24 h at regular time to estimate As uptake kinetics of the ...

  14. Modelling concept of lettuce breeding for nutrient efficiency

    NARCIS (Netherlands)

    Kerbiriou, P.J.; Stomph, T.J.; Lammerts Van Bueren, E.; Struik, P.C.

    2014-01-01

    Modern lettuce cultivars are bred for use under high levels of input of water and nutrients, and therefore less adapted to low-input or organic conditions in which nitrate availability varies over time and within the soil profile. To create robust cultivars it is necessary to assess which traits

  15. Survival of pathogenic Escherichia coli on basil, lettuce, and spinach

    Science.gov (United States)

    The contamination of lettuce, spinach and basil with pathogenic E. coli has caused numerous illnesses over the past decade. E. coli O157:H7, E. coli O104:H4 and avian pathogenic E. coli (APECstx- and APECstx+) were inoculated on basil plants and in promix soiless substrate using drip and overhead ir...

  16. Genetic transformation of lettuce ( Lactuca sativa ): A review | Dan ...

    African Journals Online (AJOL)

    Lettuce (Lactuca sativa L.) is a globally important leafy vegetable that can be grown worldwide. Due to the rapid growth of population and the human desire to progress, there have been a lot of studies made by researchers, especially in genetic engineering. Improvements in regeneration system and transformation ...

  17. The nicolet lettuce model : a theme with variations

    NARCIS (Netherlands)

    Seginer, I.; Linker, F.; Buwalda, F.; Straten, van G.

    2004-01-01

    The NICOLET model has been developed to predict the growth and nitrate content of greenhouse lettuce. Four single-organ versions have been developed: [1] abundant supply of nitrogen (1998), [2] mild N-stress (1999), [3] severe N-stress (2003), and [4] ontogenetic changes of organic-N and water

  18. Irrigation and nitrogen level affect lettuce yield in greenhouse ...

    African Journals Online (AJOL)

    This study was conducted to investigate the effect of different irrigation and nitrogen levels on lettuce yield characteristics in greenhouse condition from December 2006 to March 2007. Irrigation levels of 100% of total class A pan (S1), 80% of total class A pan (S2), 60% of total class A pan (S3) and nitrogen levels of 0 kg ...

  19. Post-harvest decay in fresh-cut lettuce

    Science.gov (United States)

    Shelf-life of fresh-cut lettuce was assessed in two mapping population (Salinas 88 x La Brillante, and Pavane x Parade. The most significant QTL was detected in both populations on linkage group 4. This QTL was detected in seven experiments grown in different environments. Molecular markers are bein...

  20. Characterization of Verticillium dahliae disease reactions in lettuce differential cultivars

    Science.gov (United States)

    Soilborne diseases significantly affect high value crops in coastal California, including lettuce and strawberry. Breeding crops for pathogen resistance is a strategy for the sustainable management of crop disease. Verticillium dahliae is a soilborne fungus that causes wilt and economic losses in a ...

  1. Unravelling the resistance mechanism of lettuce against Nasonovia ribisnigri

    NARCIS (Netherlands)

    Broeke, ten C.J.M.

    2013-01-01

    Aphids are serious pests of crop plant species, and host plant resistance is often the most effective and environmentally friendly control strategy to control these pests. One of these aphid pests is the black currant - lettuce aphid, Nasonovia ribisnigri (Mosely), an economically

  2. University Opinion Poll 9: Child Care, MPIRG, Lettuce. Preliminary Report.

    Science.gov (United States)

    Matross, Ronald; And Others

    The University Opinion Poll conducted a survey of student opinion on issues related to University-sponsored day care, the role of the Minnesota Public Interest Research Group (MPIRG) and the University's policy on buying lettuce for its food services. Four hundred fifty-two respondents, 76% of a random sample of University of Minnesota students,…

  3. Physiological analysis of methods to relieve dormancy of lettuce seeds

    NARCIS (Netherlands)

    Weges, R.

    1987-01-01

    Low maximum temperature of germination restricts the cultivation of a number of lettuce cultivars to temperate conditions. Pretreatments have been studied that increase the maximum germination temperature, which is characterized by the temperature for 50% germination (T

  4. Developing lettuce with improved quality for processed salads.

    Science.gov (United States)

    Lettuce is increasingly consumed as minimally processed salads. Cultivars grown for this market may require breeding for improved shelf-life and resistance to physiological defects such as tipburn (TB). Tipburn is a calcium deficiency related defect causing necrosis on the leaf margins, typically on...

  5. Outbreaks of gastroenteritis linked to lettuce, Denmark, January 2010

    DEFF Research Database (Denmark)

    Ethelberg, S.; Lisby, M.; Bottiger, B.

    2010-01-01

    At least 11 linked outbreaks of gastroenteritis with a total of 260 cases have occurred in Denmark in mid January 2010. Investigations showed that the outbreaks were caused by norovirus of several genotypes and by enterotoxigenic Escherichia coli. Lettuce of the lollo bionda type grown in France...

  6. Characterization and performance of 16 new inbred lines of lettuce

    Science.gov (United States)

    The Agricultural Research Service, U.S. Department of Agriculture announces the release of sixteen breeding lines of lettuce (Lactuca sativa L.). Five (SM13-I1, SM13-I2, SM13-I3, SM13-I4, and SM13-I5) of the six iceberg breeding lines can be used for whole head or salad blend production; the sixth i...

  7. Seed Production of Cutting Lettuce Varieties: Economical Facets

    Directory of Open Access Journals (Sweden)

    Н. В. Лещук

    2011-05-01

    Full Text Available The article highlights current problems of cutting lettuce seed production for all its variants. Research background is provided to the composition of material expenditures for growing of every variant in particular. Economical efficiency of seed production in line with varietal certification requirements has been reproved.

  8. "Lettuce" Learn Math: Teaching Mathematics with Seeds and Centimeters

    Science.gov (United States)

    Rickard, Laura N.; Wilson, Colette

    2006-01-01

    "Lettuce Learn Math" is an interdisciplinary program that has effectively linked a small-scale agricultural production system to a sixth-grade mathematics and science curriculum. The mathematical concepts and skills, including measurement and geometry, taught in this project met and often exceeded the standards set by New York state for…

  9. Stable plastid transformation in lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Lelivelt, Cilia L C; McCabe, Matthew S; Newell, Christine A; Desnoo, C Bastiaan; van Dun, Kees M P; Birch-Machin, Ian; Gray, John C; Mills, Kingston H G; Nugent, Jacqueline M

    2005-08-01

    Although plastid transformation in higher plants was first demonstrated in the early 1990s it is only recently that the technology is being extended to a broader range of species. To date, the production of fertile transplastomic plants has been reported for tobacco, tomato, petunia, soybean, cotton and Lesquerella fendleri (Brassicaceae). In this study we demonstrate a polyethylene glycol-mediated plastid transformation system for lettuce that generates fertile, homoplasmic, plastid-transformed lines. Transformation was achieved using a vector that targets genes to the trnA/trnI intergenic region of the lettuce plastid genome employing the aadA gene as a selectable marker against spectinomycin. Spectinomycin resistance and heterologous gene transcription were shown in T(1) plants derived from self-pollinated primary regenerants demonstrating transmission of the plastid-encoded transgene to the first seed generation. Crossing with male sterile wild-type lettuce showed that spectinomycin resistance was not transmitted via pollen. Constructs containing the gfp gene showed plastid-based expression of green fluorescent protein. The lettuce plastid could have potential both as a production and a delivery system for edible human therapeutic proteins.

  10. The resistance of lettuce to the aphid Nasonovia ribisnigri

    NARCIS (Netherlands)

    Helden, van M.

    1995-01-01

    The resistance of lettuce to the aphid Nasonovia ribisnigri is based on a single, dominant gene, the Nr-gene. On the resistant plant aphids died within a few days, without any honeydew production. Transfer-experiments with a short stay on a resistant plant followed by a

  11. Effect of irradiation on kinetic behavior of Salmonella Typhimurium and Staphylococcus aureus in lettuce and damage of bacterial cell envelope

    International Nuclear Information System (INIS)

    Shim, Won-Bo; Je, Gil-Soo; Kim, Kyeongyeol; Mtenga, Adelard B.; Lee, Won-Gyeong; Song, Jeong-Un; Chung, Duck-Hwa; Yoon, Yohan

    2012-01-01

    This study evaluated effect of gamma irradiation on survival of Salmonella Typhimurium and Staphylococcus aureus on lettuce and damage of cell envelope. S. Typhimurium and S. aureus were inoculated on red leaf lettuce, and they were irradiated at 0, 0.5, 1, 1.5, 2, 2.5, and 3 kGy, and the samples were then stored at 7 and 25 °C for 7 days. Survival of S. Typhimurium and S. aureus were enumerated on xylose lysine deoxycholate agar and Baird–Parker agar, respectively. D 10 value (dose required to reduce 1 log CFU/leaf) was calculated, and kinetic parameters (maximum specific growth rate; μ max and lag phase duration; LPD) were calculated by the modified Gompertz model. In addition, cell envelope damage of the pathogens was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). D 10 values were 0.35 and 0.33 kGy for S. Typhimurium and S. aureus, respectively. During storage at 7 °C, S. Typhimurium and S. aureus had significant (P max , respectively. At 25 °C, cell counts of S. Typhimurium and S. aureus on the samples irradiated at 0 and 0.5 kGy increased (P max of both pathogens were higher in 0 kGy (1.08–2.27 log CFU/leaf/day) and 0.5 kGy (0.58–0.92 log CFU/leaf/day), and LPDs ranged from 1.53 to 3.14 day. SEM and TEM observations showed that cells irradiated at 1.5 and 3 kGy showed disrupted cell membrane. These results indicate that gamma irradiation could be a useful decontamination technology to improve food safety of lettuce by destroying cells of S. Typhimurium and S. aureus. - Highlights: ► Low dose of gamma irradiation destroyed cell envelope of the pathogens. ► Gamma irradiation decreased cell counts of the pathogens on lettuce. ► Gamma irradiation could be useful in improving food safety of lettuce.

  12. Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation

    International Nuclear Information System (INIS)

    Sallach, J. Brett; Zhang, Yuping; Hodges, Laurie; Snow, Daniel; Li, Xu; Bartelt-Hunt, Shannon

    2015-01-01

    The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce. - Highlights: • Antimicrobial uptake in lettuce is cultivar dependent. • Antimicrobial concentrations in lettuce decrease despite repeated exposure. • Lincomycin is better conserved in the soil-plant system than oxytetracycline or sulfamethoxazole. • Subirrigation resulted in more Salmonella in bottom soil than in top soil. • Internalization frequency of Salmonella in lettuce is low despite repeated exposure. - Cultivar-specific differences in lincomycin and sulfamethazine uptake were observed in lettuce, while uptake of Salmonella was low despite repeated exposure from wastewater

  13. The inheritance of resistance to bacterial leaf spot of lettuce caused by Xanthomonas campestris pv. vitians in three lettuce cultivars

    Science.gov (United States)

    Lettuce yields can be reduced by the disease bacterial leaf spot (BLS) caused by the pathogen Xanthomonas campestris pv. vitians (Xcv) and host resistance is the most feasible method to reduce disease losses. The cultivars La Brillante, Pavane, and Little Gem express an incompatible host-pathogen in...

  14. The influence of the microbial quality of wastewater, lettuce cultivars and enumeration technique when estimating the microbial contamination of wastewater-irrigated lettuce.

    Science.gov (United States)

    Makkaew, P; Miller, M; Cromar, N J; Fallowfield, H J

    2017-04-01

    This study investigated the volume of wastewater retained on the surface of three different varieties of lettuce, Iceberg, Cos, and Oak leaf, following submersion in wastewater of different microbial qualities (10, 10 2 , 10 3 , and 10 4 E. coli MPN/100 mL) as a surrogate method for estimation of contamination of spray-irrigated lettuce. Uniquely, Escherichia coli was enumerated, after submersion, on both the outer and inner leaves and in a composite sample of lettuce. E. coli were enumerated using two techniques. Firstly, from samples of leaves - the direct method. Secondly, using an indirect method, where the E. coli concentrations were estimated from the volume of wastewater retained by the lettuce and the E. coli concentration of the wastewater. The results showed that different varieties of lettuce retained significantly different volumes of wastewater (p 0.01) were detected between E. coli counts obtained from different parts of lettuce, nor between the direct and indirect enumeration methods. Statistically significant linear relationships were derived relating the E. coli concentration of the wastewater in which the lettuces were submerged to the subsequent E. coli count on each variety the lettuce.

  15. Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation.

    Science.gov (United States)

    Sallach, J Brett; Zhang, Yuping; Hodges, Laurie; Snow, Daniel; Li, Xu; Bartelt-Hunt, Shannon

    2015-02-01

    The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Lettuce infectious yellows virus-encoded P26 induces plasmalemma deposit cytopathology

    International Nuclear Information System (INIS)

    Stewart, Lucy R.; Medina, Vicente; Sudarshana, Mysore R.; Falk, Bryce W.

    2009-01-01

    Lettuce infectious yellows virus (LIYV) encodes a 26 kDa protein (P26) previously shown to associate with plasmalemma deposits (PLDs), unique LIYV-induced cytopathologies located at the plasmalemma over plasmodesmata pit fields in companion cells and phloem parenchyma. To further characterize the relationship of P26 and PLDs, we assessed localization and cytopathology induction of P26 expressed from either LIYV or a heterologous Tobacco mosaic virus (TMV) vector using green fluorescent protein (GFP) fusions, immunofluorescence microscopy, biochemical fractionation, and transmission electron microscopy (TEM). TEM analyses demonstrated that P26 not only associated with, but induced formation of PLDs in the absence of other LIYV proteins. Interestingly, PLDs induced by P26-expressing TMV were no longer confined to phloem cells. Putative P26 orthologs from two other members of the genus Crinivirus which do not induce conspicuous PLDs exhibited fractionation properties similar to LIYV P26 but were not associated with any PLD-like cytopathology.

  17. Nutritional and taste characteristics of low-potassium lettuce developed for patients with chronic kidney diseases

    OpenAIRE

    Yoshida, Takuya; Sakuma, Kozue; Kumagai, Hiromichi

    2014-01-01

    Dietary potassium restriction is recommended for chronic kidney disease (CKD) patients with hyperkalemia. Boiling or soaking vegetables in water is known to decrease their potassium content. However, these methods can also reduce the quantity of other nutrients. Recently, low-potassium (LK) lettuce has been developed for CKD patients with hyperkalemia. This study compared the potassium content, other nutritional values, and taste characteristics of LK lettuce with those of normal lettuce. The...

  18. Genetic dissection of nonhost resistance of wild lettuce, Lactuca saligna, to downy mildew

    OpenAIRE

    Zhang, N.

    2008-01-01

    Lettuce downy mildew is the most destructive disease in lettuce (Lactuca spp.) cultivation and is caused by Bremia lactucae. The successful cross between its host L. sativa and the nonhost, L. saligna, and offers a rare chance to study the genetics of the nonhost resistance. From a set of 29 Backcross Inbred Lines (BILs) representing in total 96% of the L. saligna genome, 15 introgressions were identified to contribute to this resistance at one to four tested lettuce developmental stages and ...

  19. Plastid transformation in lettuce (Lactuca sativa L.) by biolistic DNA delivery.

    Science.gov (United States)

    Ruhlman, Tracey A

    2014-01-01

    The interest in producing pharmaceutical proteins in a nontoxic plant host has led to the development of an approach to express such proteins in transplastomic lettuce (Lactuca sativa L.). A number of therapeutic proteins and vaccine antigen candidates have been stably integrated into the lettuce plastid genome using biolistic DNA delivery. High levels of accumulation and retention of biological activity suggest that lettuce may provide an ideal platform for the production of biopharmaceuticals.

  20. THE FARMING AND MARKETING OF ORGANIC LETTUCE: STUDY AT BOBOSAN VILLAGE, KEDUNGBANTENG SUB-DISTRICT, BANYUMAS

    Directory of Open Access Journals (Sweden)

    Irene Kartika Eka Wijayanti

    2017-09-01

    Full Text Available Banyumas has great potential as a producer of organic lettuce in term of condition of natural, human resources and availability of market. The centre producer of organic lettuce is located in district of Kedungbanteng, and managed by farmers group "abdi tani". The aim of this study is to analyze: 1. The cost and income farming of organic lettuce; 2. Financial feasibility of organic lettuce farm; 3. The channel and structure of organic lettuce market. Processing and data analysis performed qualitatively and quantitatively. The data used is to the production and marketing of organic lettuce in period of June-July 2016. Quantitative analysis performed using analysis of cost, farm income, and R/C. Qualitative analysis was conducted to determine the channel and structure of organic lettuce market. The results showed that organic lettuce farm income generating positive value and the value of R/C is greater than one (R/C >1, the farming is profitable and feasible. Organic lettuce marketing channels through the use of one channel, such farmers, traders, retailers (supermarket. Farmers faced monopsony market structure, while traders and retailers deal with oligopoly one

  1. Agricultural recycling of biodigested vinasse for lettuce production

    Directory of Open Access Journals (Sweden)

    Camila Roberta Javorski Ueno

    2014-10-01

    Full Text Available The agricultural use of waste products represents an interesting alternative for nutrient cycling. Biodigested vinasse, the final waste product of vinasse biodigestion and biogas production, can be reused for agricultural purposes. The present work sought to quantify the shoot dry mass production of lettuce plants, as well as foliar nitrogen, phosphorus and potassium content following the application of biodigested vinasse on soil. Biodigested vinasse was produced from anaerobic vinasse digestion, using anaerobic sludge as a source of microorganisms. The treatments, with four replications in entirely randomized design, consisted of anaerobic sludge from a gelatin factory, vinasse in natura, biodigested vinasse and a control treatment. The experiment was conducted over 45 days using 5 L vases and applying a dose equivalent to 150 m3 ha-1 . Lettuce treated with biodigested vinasse showed higher shoot dry mass production and higher accumulation of nitrogen, phosphorus and potassium in its leaves than that treated with vinasse in natura.

  2. Fate of [14C]-zineb on lettuce plants

    International Nuclear Information System (INIS)

    Vonk, J.W.

    1976-01-01

    [1,2- 14 C]-zinc ethylenebisdithiocarbamate (zineb) was prepared and applied in droplets to leaves of lettuce plants. In aqueous suspension zineb decomposes mainly into ethylenethiourea (ETU) and 5,6-dihydro-3H-imidazo[2,1-C]-1,2,4-dithiazole-3-thione (DIDT). Lettuce plants were harvested 0,1,3,7,14 and 21 days after treatment and analysed. A high proportion of radioactivity remained on the surface of the plant and could be washed off. The following identified products were present: unchanged zineb, ETU, DIDT, 2-imidazoline and ethyleneurea. The ETU residue disappeared within 7 days, while 2-imidazoline and ethyleneurea were formed gradually. Radioactivity inside the plant consisted mostly of ethyleneurea: no ETU was present. (author)

  3. Effect of pressure on the vacuum cooling of iceberg lettuce

    Energy Technology Data Exchange (ETDEWEB)

    Ozturk, Hande Mutlu [Pamukkale University, Food Engineering Department, Faculty of Engineering, Denizli (Turkey); Ozturk, Harun Kemal [Pamukkale University, Mechanical Engineering Department, Faculty of Engineering, 20070 Kinikli, Denizli (Turkey)

    2009-05-15

    Vacuum cooling is known as a rapid evaporative cooling technique for any porous product which has free water. The aim of this paper is to apply vacuum cooling technique to the cooling of the iceberg lettuce and show the pressure effect on the cooling time and temperature decrease. The results of vacuum cooling are also compared with conventional cooling (cooling in refrigerator) for different temperatures. Vacuum cooling of iceberg lettuce at 0.7 kPa is about 13 times faster than conventional cooling of iceberg lettuce at 6 C. It has been also found that it is not possible to decrease the iceberg lettuce temperature below 10 C if vacuum cooling method is used and vacuum pressure is set to 1.5 kPa. (author) [French] Le refroidissement sous vide est connu comme une technique evaporative rapide refroidissant pour n'importe quel produit poreux qui a de l'eau libre. Le but de ce papier est d'appliquer le refroidissement sous vide pour le refroidissement de la laitue et examiner l'effet de la pression sur le temps de refroidissement et la diminution de temperature. Les resultats de refroidissement sous vide sont aussi compares avec le refroidissement conventionnel (refroidissement dans le refrigerateur) pour les differentes temperatures. Le refroidissement a vide de laitue a 0.7 kPa est environ 13 fois plus vite que le refroidissement conventionnel de laitue croquante a 6 C. Il a ete aussi constate qu'il n'est pas possible de diminuer la temperature de laitue ci-dessous 10 C si le refroidissement sous vide est utilise comme methode et la pression a vide est montree a 1.5 kPa. (orig.)

  4. Colonization of lettuce rhizosphere and roots by tagged Streptomyces

    OpenAIRE

    Maria eBonaldi; Xiaoyulong eChen; Andrea eKunova; Cristina ePizzatti; Marco eSaracchi; Paolo eCortesi

    2015-01-01

    Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plas...

  5. Colonization of lettuce rhizosphere and roots by tagged Streptomyces

    Directory of Open Access Journals (Sweden)

    Maria eBonaldi

    2015-02-01

    Full Text Available Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plasmid harboring an enhanced green fluorescent protein marker and resistance to apramycin. The fitness of transformants was compared to the wild-type strains and all of them grew and sporulated at similar rates and retained the production of enzymes and selected secondary metabolites as well as in vitro inhibition of S. sclerotiorum. The tagged ZEA17I strain was selected to study the dynamics of lettuce roots and rhizosphere colonization in non-sterile growth substrate. The transformed strain was able to colonize soil, developing roots and rhizosphere. When the strain was inoculated directly on the growth substrate, significantly more t-ZEA17I was re-isolated both from the rhizosphere and the roots when compared to the amount obtained after seed coating. The re-isolation from the rhizosphere and the inner tissues of surface-sterilized lettuce roots demonstrated that t-ZEA17I is both rhizospheric and endophytic.

  6. Physiological and health quality of commercial lettuce and cabbage seed

    Directory of Open Access Journals (Sweden)

    Cleyton Teles Contreiras Paiva

    2016-08-01

    Full Text Available Physiological and sanitary seed quality is essential for rapid and uniform crop establishment at field, a factor which contributes to vegetable crop production success. The aim was to evaluate physiological and sanitary quality of lettuce and cabbage seeds coming three lots acquired in trade. Physiological quality was determined by means of germination test and index of speed germination. Health status was assessed through sanity test in Petri dishes containing BDA medium. The experimental design was completely randomized with four replications and the averages of each lot compared among themselves by Tukey test (5%. No statistical analyzes were performed to health test and samples were evaluated for presence of microorganisms on the plates. Aspergillus spp., Rhizopus spp., cocci and bacillus are associated with lettuce seeds, and Aspergillus spp., cocci and bacillus are associated with cabbage seeds, but this association can not interfere with germination performance at laboratory. Information about germination contained in the package do not always coincide with those examined in situ. Lettuce and cabbage seeds are being marketed carrying pathogens.

  7. Research on lettuce growth technology onboard Chinese Tiangong II Spacelab

    Science.gov (United States)

    Shen, Yunze; Guo, Shuangsheng; Zhao, Pisheng; Wang, Longji; Wang, Xiaoxia; Li, Jian; Bian, Qiang

    2018-03-01

    Lettuce was grown in a space vegetable cultivation facility onboard the Tiangong Ⅱ Spacelab during October 18 to November 15, 2016, in order to testify the key cultivating technology in CELSS under spaceflight microgravity condition. Potable water was used for irrigation of rooting substrate and the SRF (slowly released fertilizer) offered mineral nutrition for plant growth. Water content and electric conductivity in rooting substrate were measured based on FDR(frequency domain reflectometry) principle applied first in spaceflight. Lettuce germinated with comparative growth vigor as the ground control, showing that the plants appeared to be not stressed by the spaceflight environment. Under microgravity, lettuce grew taller and showed deeper green color than the ground control. In addition, the phototropism of the on-orbit plants was more remarkable. The nearly 30-d spaceflight test verified the seed fixation technology and water& nutrition management technology, which manifests the feasibility of FDR being used for measuring moisture content and electric conductivity in rooting zone under microgravity. Furthermore, the edibility of the space-grown vegetable was proved, providing theoretical support for astronaut to consume the space vegetable in future manned spaceflight.

  8. Purification, characterization and immunomodulatory activity of polysaccharides from stem lettuce.

    Science.gov (United States)

    Nie, Chenzhipeng; Zhu, Peilei; Ma, Shuping; Wang, Mingchun; Hu, Youdong

    2018-05-15

    Stem lettuce has a long history of cultivation in China and possesses high nutritional and medicinal value. In our previous studies, extraction optimization, characterization, and bioactivities of stem lettuce polysaccharides (SLP) were investigated. In this study, SLP were further separated into two purified polysaccharides, SLP-1 and SLP-2, by anion exchange chromatography followed by size exclusion chromatography. SLP-1, with a molecular weight of 90 KDa, was mainly composed of galacturonic acid, galactose and arabinose in a molar ratio of 17.6:41.7:33.9. SLP-2, with a molecular weight of 44 KDa, was mainly composed of mannose, galacturonic acid, galactose and arabinose in a molar ratio of 11.5:69.5:9.3:8.2. In addition, both purified polysaccharides contain sulphate radicals, have triple helical structures and can promote macrophage proliferation without cytotoxicity. SLP-2 was better able to stimulate phagocytic and nitric oxide production than SLP-1. The results suggest that polysaccharides from stem lettuce could be explored as immunomodulatory agents in the field of pharmaceuticals and functional foods. Copyright © 2018 Elsevier Ltd. All rights reserved.

  9. Jatropha press cake as organic fertilizer in lettuce cultivation

    Directory of Open Access Journals (Sweden)

    José R. Mantovani

    Full Text Available ABSTRACT In biodiesel production, vegetable press cake is obtained as waste, and a suitable destination for jatropha press cake would be the use in agriculture as organic fertilizer. This study aimed to evaluate the effect of jatropha press cake on soil fertility attributes and on lettuce production and accumulation of nutrients in the shoots. The experiment was conducted in pots in a greenhouse, in a randomized block design with eight treatments and five replicates. The treatments consisted of doses of jatropha press cake equivalent to 0, 0.5, 1.0, 2.0, 4.0, 8.0, 16.0 and 32.0 t ha-1. Portions of 5.5 dm3 of soil received limestone, phosphate fertilizer and the doses of jatropha press cake, and remained incubated for 30 days. After incubation, soil samples were collected, each pot received one lettuce seedling and the experiment was carried out for 45 days. The organic fertilization with jatropha press cake increased the contents of nutrients in the soil, especially K+, but caused increment in soil acidity and electrical conductivity. The use of jatropha press cake as organic fertilizer decreased lettuce production and accumulation of nutrients in the shoots.

  10. Possible Internalization of an Enterovirus in Hydroponically Grown Lettuce.

    Science.gov (United States)

    Carducci, Annalaura; Caponi, Elisa; Ciurli, Adriana; Verani, Marco

    2015-07-17

    Several studies have shown that enteric viruses can be transferred onto the surface of vegetables and fruits through spray irrigation, but, recently, reports have suggested viral contamination of vegetables sub-irrigated with reused wastewater. Hydroponic cultures, used to grow ready to eat fresh lettuce, have also been used to study the possibility of viral absorption through roots. This study was conducted to assess a possible risk of viral contamination in lettuce from contaminated water. The leaves of lettuce plants grown in hydroponic cultures where the roots were exposed to water containing Coxsakievirus B2, were analysed for evidence of the virus. The plants and water were sampled at different times and virus was measured using quantitative RT-PCR and infectivity assay. In leaf samples, the lowest observed infective data were lower than the qRT-PCR detection limits, suggesting that free viral RNA or damaged viruses are eliminated rapidly while infectious particles remain stable for a longer time. The obtained data revealed that the leaves were contaminated at a water concentration of 4.11 ± 1 Log Most Probable Number/L (8.03 ± 1 Log GC/L) a concentration observed in contaminated untreated water of wastewater treatment plants. However, the absorption dynamics and whether the virus is inactive in the leaves still remains to be clarified. Nevertheless, this work has practical implications for risk management in using reclaimed water for agricultural use; when irrigated vegetables are destined for raw consumption, virological contamination in water sources should be evaluated.

  11. Colonization of lettuce rhizosphere and roots by tagged Streptomyces.

    Science.gov (United States)

    Bonaldi, Maria; Chen, Xiaoyulong; Kunova, Andrea; Pizzatti, Cristina; Saracchi, Marco; Cortesi, Paolo

    2015-01-01

    Beneficial microorganisms are increasingly used in agriculture, but their efficacy often fails due to limited knowledge of their interactions with plants and other microorganisms present in rhizosphere. We studied spatio-temporal colonization dynamics of lettuce roots and rhizosphere by genetically modified Streptomyces spp. Five Streptomyces strains, strongly inhibiting in vitro the major soil-borne pathogen of horticultural crops, Sclerotinia sclerotiorum, were transformed with pIJ8641 plasmid harboring an enhanced green fluorescent protein marker and resistance to apramycin. The fitness of transformants was compared to the wild-type strains and all of them grew and sporulated at similar rates and retained the production of enzymes and selected secondary metabolites as well as in vitro inhibition of S. sclerotiorum. The tagged ZEA17I strain was selected to study the dynamics of lettuce roots and rhizosphere colonization in non-sterile growth substrate. The transformed strain was able to colonize soil, developing roots, and rhizosphere. When the strain was inoculated directly on the growth substrate, significantly more t-ZEA17I was re-isolated both from the rhizosphere and the roots when compared to the amount obtained after seed coating. The re-isolation from the rhizosphere and the inner tissues of surface-sterilized lettuce roots demonstrated that t-ZEA17I is both rhizospheric and endophytic.

  12. Antimicrobial activities of tapioca starch/decolorized hsian-tsao leaf gum coatings containing green tea extracts in fruit-based salads, romaine hearts and pork slices.

    Science.gov (United States)

    Chiu, Po-En; Lai, Lih-Shiuh

    2010-04-30

    The antimicrobial activities of edible coatings based on a tapioca starch/decolorized hsian-tsao leaf gum (dHG) matrix with various green tea extracts (GTEs) were evaluated. Its effect on the shelf-life extension of fruit-based salads, romaine hearts, and pork slices were investigated as well. Three types of GTEs from hot water (80 degrees C) (W), 40% (E4) and 80% (E8) ethanol were prepared. It was found that all GTEs showed pronounced inhibition on Gram positive bacteria in agar media, including Staphylococcus aureus BCRC 10781, Bacillus cereus BCRC 11778 and Listeria monocytogenes BCRC 14848, but not on Gram negative bacteria, such as Escherichia coli DH10beta and Salmonella enteria BCRC 10747. The antimicrobial activities increased with increasing GTEs concentration (1, 2 and 5%), but did not differentiate significantly in terms of the effect of extraction solvents. When various GTEs (1%) were added to an edible coating formulation based on 1.35% tapioca starch +0.15% dHG +0.225% glycerol, pronounced antimicrobial activity on Gram positive bacteria was also observed as evaluated by using cylinder diffusion and antimicrobial migration tests. It was believed that the active compounds in green tea extracts could leave the coating matrix and migrate to increase the non-growth area. When being sprayed on various real food models, all tapioca starch/dHG coatings containing GTEs could successfully reduce the aerobic counting and growth of yeasts/molds by 1 to 2 log cycles in fruit-based salads, as compared to the control sample. Furthermore, during refrigerated storage of romaine hearts and pork slices for 48h, tapioca starch/dHG coatings with E4 extracts demonstrated pronounced antimicrobial activity against Gram positive bacteria (4-6 log cycles reduction), followed by W extracts and E8 extracts in a decreasing order. Such results implied the high efficacy of antimicrobial migration of tapioca starch/dHG coatings containing GTEs and their application potentials on

  13. Zooming in on the lettuce genome: species relationships in Lactuca s.l., inferred from chromosomal and molecular characters

    OpenAIRE

    Koopman, W.J.M.

    2002-01-01

    Lactuca sativa (cultivated lettuce) is the world's most important leafy salad vegetable. Apart from L. sativa , the genus Lactuca contains ca. 75 wild species, potentially useful to improve, for example, taste, texture, and disease resistance of cultivated lettuce. The wild species L. serriola (Prickly Lettuce), L. saligna (Least Lettuce), and L. virosa (Great...

  14. 76 FR 81468 - Notice of Decision to Authorize the Importation of Shredded Lettuce From Egypt Into the...

    Science.gov (United States)

    2011-12-28

    ...] Notice of Decision to Authorize the Importation of Shredded Lettuce From Egypt Into the Continental... fresh shredded lettuce from Egypt. Based on the findings of a pest risk analysis, which we made... introducing or disseminating plant pests or noxious weeds via the importation of fresh shredded lettuce from...

  15. 76 FR 50992 - Notice of Availability of a Pest Risk Analysis for the Importation of Shredded Lettuce From Egypt

    Science.gov (United States)

    2011-08-17

    ...] Notice of Availability of a Pest Risk Analysis for the Importation of Shredded Lettuce From Egypt AGENCY... into the continental United States of fresh shredded lettuce from Egypt. Based on this analysis, we... fresh shredded lettuce from Egypt. We are making the pest risk analysis available to the public for...

  16. Optimal control of nitrate in lettuce by a hybrid approach: differential evolution and adjustable control weight gradient algorithms

    NARCIS (Netherlands)

    Lopez Cruz, I.L.; Willigenburg, van L.G.; Straten, van G.

    2003-01-01

    Abstract Since high concentration levels of nitrate in lettuce and other leafy vegetables are undesirable, cultivation of lettuce according to specified governmental regulations is currently an important issue. Therefore, methods are sought in order to produce a lettuce crop that allow maximization

  17. Production system and harvesting stage influence on nitrate content and quality of butterhead lettuce

    Directory of Open Access Journals (Sweden)

    Siti Fairuz Yosoff

    2015-01-01

    Full Text Available Leafy vegetables such as lettuce grown under different production systems may accumulate different concentrations of nitrate which may reach to the levels potentially toxic to humans. Moreover, nitrate accumulation varies in various plant parts and physiological age of the plant. Therefore, to determine the effect of production system and harvesting stage on nitrate accumulation and quality of butterhead lettuce, a study was conducted considering two lettuce production systems namely hydroponic and organic, and four different harvesting stages such as 35, 38, 41 and 44 days after transplanting (DAT. The experimental design was complete randomized design (CRD with four replications. Hydroponic and organic systems performed similar in terms of yield, quality and nitrate content of butterhead lettuce. Delaying harvesting can not only increase yield but also can minimize nitrate accumulation and health hazard risk as well. Delay in harvesting stage may result in quality deterioration of lettuce and increased production cost. Thus, a compromise is necessary to consider 41 DAT as the optimum stage to harvest butterhead lettuce with significantly higher reduction of nitrate content in both outer adult leaf blades and young leaves of hydroponic lettuce. Fresh weight, firmness and color of butterhead lettuce at this stage were still acceptable.

  18. Exploring the Limits of Crop Productivity: High Light Studies with Lettuce

    OpenAIRE

    USU Crop Physiology Lab

    2015-01-01

    There are many different leaf lettuce cultivars and they range in color from light green and yellow to deep green as a result of higher concentrations of chlorophyll in the leaves. We tested four cultivars in high light to explore the limits of lettuce productivity.

  19. Nondestructive phenotyping of lettuce plants in early stages of development with optical sensors

    Science.gov (United States)

    Rapid development of plants is important for the production of ‘baby-leaf’ lettuce that is harvested when plants reach the four- to eight-leaf stage of growth. However, environmental factors, such as high or low temperature, or elevated concentrations of salt, inhibit lettuce growth. Therefore, nond...

  20. A detailed linkage map of lettuce based on SSAP, AFLP and NBS markers

    NARCIS (Netherlands)

    Syed, H.; Sorensen, A.P.; Antonise, R.; van de Wiel, C.; van der Linden, C.G.; van 't Westende, W.; Hooftman, D.A.P.; den Nijs, J.C.M.; Flavell, A.J.

    2006-01-01

    Abstract Molecular markers based upon a novel lettuce LTR retrotransposon and the nucleotide binding site-leucine-rich repeat (NBS-LRR) family of disease resistance-associated genes have been combined with AFLP markers to generate a 458 locus genetic linkage map for lettuce. A total of 187

  1. Fluorescence hyperspectral imaging technique for the foreign substance detection on fresh-cut lettuce

    Science.gov (United States)

    Nondestructive methods based on fluorescence hyperspectral imaging (HSI) techniques were developed in order to detect worms on fresh-cut lettuce. The optimal wavebands for detecting worms on fresh-cut lettuce were investigated using the one-way ANOVA analysis and correlation analysis. The worm detec...

  2. Accuracy, reliability, and timing of visual evaluations of decay in fresh-cut lettuce

    Science.gov (United States)

    Visual assessments are used for evaluating the quality of food products, such as fresh-cut lettuce packaged in bags with modified atmosphere. We have compared the accuracy and the reliability of visual evaluations of decay on fresh-cut lettuce performed with experienced and inexperienced raters. In ...

  3. Dissipation and Residues of Pyrethrins in Leaf Lettuce under Greenhouse and Open Field Conditions.

    Science.gov (United States)

    Pan, Lixiang; Feng, Xiaoxiao; Zhang, Hongyan

    2017-07-21

    Pyrethrins are nowadays widely used for prevention and control of insects in leaf lettuce. However, there is a concern about the pesticide residue in leaf lettuce. A reliable analytical method for determination of pyrethrins (pyrethrin-and П, cinerin І and П, and jasmolin І and П) in leaf lettuce was developed by using gas chromatography-mass spectrometry (GC-MS). Recoveries of pyrethrins in leaf lettuce at three spiking levels were 99.4-104.0% with relative standard deviations of 0.9-3.1% ( n = 5). Evaluation of dissipation and final residues of pyrethrins in leaf lettuce were determined at six different locations, including the open field, as well as under greenhouse conditions. The initial concentration of pyrethrins in greenhouse (0.57 mg/kg) was higher than in open field (0.25 mg/kg) and the half-life for pyrethrins disappearance in field lettuce (0.7 days) was less than that greenhouse lettuce (1.1 days). Factors such as rainfall, solar radiation, wind speed, and crop growth rate are likely to have caused these results. The final residue in leaf lettuce was far below the maximum residue limits (MRLs) (1 mg/kg established by the European Union (EU), Australia, Korea, Japan).

  4. Genetics of the partial resistance against race 2 of Verticillium dahliae in lettuce

    Science.gov (United States)

    Lettuce (Lactuca sativa L.) production on the Coastal California is threatened by Verticillium wilt, a soil borne fungal disease caused by Verticillium dahliae that diminishes yield and quality. Two races of V. dahliae were identified on lettuce, race 1 and race 2. Complete resistance to race 1 is c...

  5. On-line fresh-cut lettuce quality measurement system using hyperspectral imaging

    Science.gov (United States)

    Lettuce, which is a main type of fresh-cut vegetable, has been used in various fresh-cut products. In this study, an online quality measurement system for detecting foreign substances on the fresh-cut lettuce was developed using hyperspectral reflectance imaging. The online detection system with a s...

  6. Screening of lettuce germplasm for agronomic traits under low water conditions

    Science.gov (United States)

    After a preliminary screening of over 3,500 varieties, we selected 200 cultivars of butterhead, cos, crisphead, leaf, and stem lettuce (Lactuca sativa L.) and wild prickly lettuce (Lactuca serriola L.) to test under high water (150% ET) and low water (50% ET) conditions in the field, and tracked com...

  7. Genetic dissection of nonhost resistance of wild lettuce, Lactuca saligna, to downy mildew

    NARCIS (Netherlands)

    Zhang, N.

    2008-01-01

    Lettuce downy mildew is the most destructive disease in lettuce (Lactuca spp.) cultivation and is caused by Bremia lactucae. The successful cross between its host L. sativa and the nonhost, L. saligna, and offers a rare chance to study the genetics of the nonhost resistance. From a set of 29

  8. Incorporation of temperature and solar radiation thresholds to modify a lettuce downy mildew warning system

    NARCIS (Netherlands)

    Wu, B.M.; Bruggen, van A.H.C.; Subbarao, K.V.; Scherm, H.

    2002-01-01

    The effect of temperature on infection of lettuce by Bremia lactucae was investigated in controlled environment studies and in the field. In controlled conditions, lettuce seedlings inoculated with B. lactucae were incubated at 15, 20, 25, or 30°C during a 4-h wet period immediately after

  9. Antioxidant capacity and contents of phenols, ascorbic acid, β-carotene and lycopene in lettuce

    Directory of Open Access Journals (Sweden)

    Zdravković Jasmina M.

    2014-01-01

    Full Text Available The antioxidant activity of three lettuce varieties (Lactuca sativa L. Emerald, Vera and Neva, cultivated in two kinds of protected spaces, a glasshouse and a plastic greenhouse, under controlled conditions, was determined. The content of antioxidant compounds: total phenols, flavonoids, L-ascorbic acid, ß-carotene and lycopene, were determined in ethanolic extracts of the lettuce with spectrophotometric methods. The largest content of total phenols (78.98 ± 0.67 mg GAE/g of dry extract was found in ethanolic extract of the lettuce variety Neva cultivated in a plastic greenhouse, whereas the largest content of flavonoids (35.45 ± 0.95 mg RU/g of dry extract was displayed in the lettuce Emerald cultivated in a glasshouse. It was observed that the lettuce cultivated in the glasshouse contained a somewhat higher content of L-ascorbic acid than the lettuce same variety from plastic greenhouse. The content of lycopene in the examined lettuce is negligible, and the content of ß-carotene is low. On the other hand, the high content of phenolic components causes favourable antioxidant properties found in all varieties of examined lettuce. [Projekat Ministarstva nauke Republike Srbije, br. TR 31059: A new concept in breeding vegetable cultivars and hybrids designed for sustainable growing systems using biotechnological methods

  10. Reducing microbial contamination on wastewater-irrigated lettuce by cessation of irrigation before harvesting

    DEFF Research Database (Denmark)

    Keraita, Bernard; Konradsen, Flemming; Drechsel, Pay

    2007-01-01

    OBJECTIVE: To assess the effectiveness of cessation of irrigation before harvesting in reducing microbial contamination of lettuce irrigated with wastewater in urban vegetable farming in Ghana. METHODS: Assessment was done under actual field conditions with urban vegetable farmers in Ghana. Trials...... were arranged in completely randomized block design and done both in the dry and wet seasons. Seven hundred and twenty-six lettuce samples and 36 water samples were analysed for thermotolerant coliforms and helminth eggs. RESULTS: On average, 0.65 log units for indicator thermotolerant coliforms and 0.......4 helminth eggs per 100 g of lettuce were removed on each non-irrigated day from lettuce in the dry season. This corresponded to a daily loss of 1.4 tonnes/ha of fresh weight of lettuce. As an input for exposure analysis to make risk estimates, the decay coefficient, k, for thermotolerant coliforms was 0...

  11. Transfer and expression of the rabbit defensin NP-1 gene in lettuce (Lactuca sativa).

    Science.gov (United States)

    Song, D; Xiong, X; Tu, W F; Yao, W; Liang, H W; Chen, F J; He, Z Q

    2017-01-23

    Lettuce (Lactuca sativa L.) is an annual plant of the daisy family, Asteraceae, with high food and medicinal value. However, the crop is susceptible to several viruses that are transmitted by aphids and is highly vulnerable to post-harvest diseases, as well as insect and mammal pests and fungal and bacterial diseases. Here, the rabbit defensin gene NP-1 was transferred into lettuce by Agrobacterium-mediated transformation to obtain a broad-spectrum disease-resistant lettuce. Transgenic lettuce plants were selected and regenerated on selective media. The presence of the NP-1 gene in these plants was confirmed by western blot analyses. Resistance tests revealed native defensin NP-1 expression conferred partial resistance to Bacillus subtilis and Pseudomonas aeruginosa, which suggests new possibilities for lettuce disease resistance.

  12. Association analysis of bacterial leaf spot resistance and SNP markers derived from expressed sequence tags (ESTs) in lettuce (Lactuca sativa L.)

    Science.gov (United States)

    Bacterial leaf spot of lettuce, caused by Xanthomonas campestris pv. vitians, is a devastating disease of lettuce worldwide. Since there are no chemicals available for effective control of the disease, host-plant resistance is highly desirable to protect lettuce production. A total of 179 lettuce ge...

  13. Microbial Profile of Soil-Free versus In-Soil Grown Lettuce and Intervention Methodologies to Combat Pathogen Surrogates and Spoilage Microorganisms on Lettuce

    Directory of Open Access Journals (Sweden)

    Sujata A. Sirsat

    2013-11-01

    Full Text Available Aquaponics is an effective method to practice sustainable agriculture and is gaining popularity in the US; however, the microbial safety of aquaponically grown produce needs to be ascertained. Aquaponics is a unique marriage of fish production and soil-free produce (e.g., leafy greens production. Fish are raised in fresh water tanks that are connected to water filled beds where fruits and vegetables are grown. The fish bi-products create nutrient-rich water that provides the key elements for the growth of plants and vegetables. The objective of this study was to perform a comparative analysis of the microbial safety and quality of aquaponic lettuce and soil grown lettuce (conventional, bagged, certified organic, and field lettuce. Following this, an intervention study was performed to combat foodborne pathogen surrogates (Salmonella and E. coli, spoilage, and fecal microorganisms using 2.5% acetic acid. The results of the comparative analysis study showed that aquaponically grown lettuce had significantly lower concentration of spoilage and fecal microorganisms compared to in-soil grown lettuce. The intervention study showed that diluted vinegar (2.5% acetic acid significantly reduced Salmonella, E. coli, coliforms, and spoilage microorganisms on fresh lettuce by 2 to 3 log CFU/g. Irrespective of growing methods (in-soil or soilless, it is crucial to incorporate good agricultural practices to reduce microbial contamination on fresh produce. The intervention employed in this study can be proposed to small farmers and consumers to improve quality and safety of leafy greens.

  14. Microbial Profile of Soil-Free versus In-Soil Grown Lettuce and Intervention Methodologies to Combat Pathogen Surrogates and Spoilage Microorganisms on Lettuce.

    Science.gov (United States)

    Sirsat, Sujata A; Neal, Jack A

    2013-11-11

    Aquaponics is an effective method to practice sustainable agriculture and is gaining popularity in the US; however, the microbial safety of aquaponically grown produce needs to be ascertained. Aquaponics is a unique marriage of fish production and soil-free produce (e.g., leafy greens) production. Fish are raised in fresh water tanks that are connected to water filled beds where fruits and vegetables are grown. The fish bi-products create nutrient-rich water that provides the key elements for the growth of plants and vegetables. The objective of this study was to perform a comparative analysis of the microbial safety and quality of aquaponic lettuce and soil grown lettuce (conventional, bagged, certified organic, and field lettuce). Following this, an intervention study was performed to combat foodborne pathogen surrogates ( Salmonella and E. coli ), spoilage, and fecal microorganisms using 2.5% acetic acid. The results of the comparative analysis study showed that aquaponically grown lettuce had significantly lower concentration of spoilage and fecal microorganisms compared to in-soil grown lettuce. The intervention study showed that diluted vinegar (2.5% acetic acid) significantly reduced Salmonella , E. coli , coliforms, and spoilage microorganisms on fresh lettuce by 2 to 3 log CFU/g. Irrespective of growing methods (in-soil or soilless), it is crucial to incorporate good agricultural practices to reduce microbial contamination on fresh produce. The intervention employed in this study can be proposed to small farmers and consumers to improve quality and safety of leafy greens.

  15. Possible Internalization of an Enterovirus in Hydroponically Grown Lettuce

    Directory of Open Access Journals (Sweden)

    Annalaura Carducci

    2015-07-01

    Full Text Available Several studies have shown that enteric viruses can be transferred onto the surface of vegetables and fruits through spray irrigation, but, recently, reports have suggested viral contamination of vegetables sub-irrigated with reused wastewater. Hydroponic cultures, used to grow ready to eat fresh lettuce, have also been used to study the possibility of viral absorption through roots. This study was conducted to assess a possible risk of viral contamination in lettuce from contaminated water. The leaves of lettuce plants grown in hydroponic cultures where the roots were exposed to water containing Coxsakievirus B2, were analysed for evidence of the virus. The plants and water were sampled at different times and virus was measured using quantitative RT-PCR and infectivity assay. In leaf samples, the lowest observed infective data were lower than the qRT-PCR detection limits, suggesting that free viral RNA or damaged viruses are eliminated rapidly while infectious particles remain stable for a longer time. The obtained data revealed that the leaves were contaminated at a water concentration of 4.11 ± 1 Log Most Probable Number/L (8.03 ± 1 Log GC/L a concentration observed in contaminated untreated water of wastewater treatment plants. However, the absorption dynamics and whether the virus is inactive in the leaves still remains to be clarified. Nevertheless, this work has practical implications for risk management in using reclaimed water for agricultural use; when irrigated vegetables are destined for raw consumption, virological contamination in water sources should be evaluated.

  16. Ability of Shiga toxigenic Escherichia coli to survive within dry-surface biofilms and transfer to fresh lettuce.

    Science.gov (United States)

    Adator, Emelia Hornam; Cheng, Meining; Holley, Rick; McAllister, Tim; Narvaez-Bravo, Claudia

    2018-03-23

    Biofilms are known to play important roles in bacterial survival and persistence in food-processing environments. This study aimed to determine the ability of the top 7 STEC serotypes to form biofilms on polystyrene (POL) and stainless steel (SS) plates and to quantify their survival and transfer from dry-surface biofilms to lettuce pieces. The ability of 14 STEC strains to form biofilms on these two materials at different exposure times and temperatures was assessed using crystal violet, Congo red and SEM. At 10 °C all serotypes were weak biofilm producers on both surfaces. In contrast, serotypes O45-040, O45-445, O103-102, O103-670 and O157-R508 were strong biofilm producers at 25 °C. Strains O103-102, O103-670, O111-CFS, O111-053 and O157:H7-R508 were expressers of curli. Under scanning electron microscopy, strains O103-670, O111-CFS, O157-R508, and O121-083 formed more discernible multilayer, mature biofilms on SS coupons. Regardless of the surface (POL/SS), all STEC strains were able to transfer viable cells onto fresh lettuce within a short contact time (2 min) to varying degrees (up to 6.35 log cfu/g). On POL, viable cell of almost all serotypes exhibited decreased detachment (p = 0.001) over 6 days; while after 30 days on SS, serotypes O45-040, O103-102, O103-670, O111-053, O111-CFS, O121-083, O145-231 O157:H7-R508 and O157:H7-122 were transferred to lettuce. After enrichment, all 14 STEC strains were recovered from dry-surface biofilms on POL and SS plates after 30 days. Results demonstrated that the top 7 STEC remained viable within dry-surface biofilms for at least 30 days, transferring to lettuce within 2 min of exposure and acting as a source of adulteration. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

  17. Nutrient absorption and response of lettuce to phosphorus fertilization

    OpenAIRE

    Antonio Ismael Inácio Cardoso; Cristiaini Kano; Roberto Lyra Villas Boas

    2012-01-01

    The objective of this study was to evaluate the response of lettuce (cultivar Verônica) to different levels of phosphorus fertilization. The experiment was conducted from 25/09/2003 (sowing) to 03/12/2003 (harvesting) at the Fazenda Experimental São Manuel, UNESP/FCA, Botucatu/SP, under protective structures. The experiment was conducted in a randomized block design, with five treatments (0, 200, 400, 600 and 800kg.ha-1 of P2O5, in the form of triple superphosphate) and five replications. Pla...

  18. Stimulating productivity of hydroponic lettuce in controlled environments with triacontanol

    Science.gov (United States)

    Knight, S. L.; Mitchell, C. A.

    1987-01-01

    Triacontanol (1-triacontanol) applied as a foliar spray at 10(-7) M to 4-day-old, hydroponically grown leaf lettuce (Lactuca sativa L.) seedlings in a controlled environment increased leaf fresh and dry weight 13% to 20% and root fresh and dry weight 13% to 24% 6 days after application, relative to plants sprayed with water. When applied at 8 as well as 4 days after seeding, triacontanol increased plant fresh and dry weight, leaf area, and mean relative growth rate 12% to 37%. There was no benefit of repeating application of triacontanol in terms of leaf dry weight gain.

  19. Assessing nitrogen supply potential and influence on growth of lettuce and amaranthus of different aged composts

    International Nuclear Information System (INIS)

    Akhtar, M.J.; Young, I.; Irvine, R.J.; Sturrock, C.

    2010-01-01

    This study assessed the potential of different composts at different maturity stages to supply N and their effect on the vegetative growth of lettuce and Amaranthus. Five composts aged 1, 3, 6, 9, and 12 months, were mixed with soil at the rate of 5%, 10% and 15% then seeded with lettuce and Amaranthus. Results showed that 1, 3 and 6 month aged composts had a negative effect on plant height of lettuce and Amaranthus as 1-15.78% and 4.78 to 29.45% decrease in plant height over control was recorded respectively. On the other hand 9 and 12 month aged composts had a significant positive effect on plant height of lettuce and Amaranthus where 43.48% and 34.8% increase over control was recorded with the application of 15% of 12 month aged compost respectively. A similar effect was observed on fresh biomass of both lettuce and Amaranthus where a 386% and 59.43% increase over control was recorded with the application of 15% of 12 month aged compost respectively. One and three month aged composts revealed a negative effect on N absorption by lettuce whereas 1, 3, 6 and 9 month aged composts had a negative effect on N absorption by Amaranthus. 30.39% and 21.48% increases over control in N absorption by lettuce and Amaranthus respectively were recorded with the application of 15% of 12 month aged compost. (author)

  20. Sampling Plans for the Thrips Frankliniella schultzei (Thysanoptera: Thripidae) in Three Lettuce Varieties.

    Science.gov (United States)

    Silva, Alisson R; Rodrigues-Silva, Nilson; Pereira, Poliana S; Sarmento, Renato A; Costa, Thiago L; Galdino, Tarcísio V S; Picanço, Marcelo C

    2017-12-05

    The common blossom thrips, Frankliniella schultzei Trybom (Thysanoptera: Thripidae), is an important lettuce pest worldwide. Conventional sampling plans are the first step in implementing decision-making systems into integrated pest management programs. However, this tool is not available for F. schultzei infesting lettuce crops. Thus, the objective of this work was to develop a conventional sampling plan for F. schultzei in lettuce crops. Two sampling techniques (direct counting and leaf beating on a white plastic tray) were compared in crisphead, looseleaf, and Boston lettuce varieties before and during head formation. The frequency distributions of F. schultzei densities in lettuce crops were assessed, and the number of samples required to compose the sampling plan was determined. Leaf beating on a white plastic tray was the best sampling technique. F. schultzei densities obtained with this technique were fitted to the negative binomial distribution with a common aggregation parameter (common K = 0.3143). The developed sampling plan is composed of 91 samples per field and presents low errors in its estimates (up to 20%), fast execution time (up to 47 min), and low cost (up to US $1.67 per sampling area). This sampling plan can be used as a tool for integrated pest management in lettuce crops, assisting with reliable decision making in different lettuce varieties before and during head formation. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. The effect of growth conditions on flavonols and anthocyanins accumulation in green and red lettuce

    Directory of Open Access Journals (Sweden)

    Klaudia BRÜCKOVÁ

    2016-12-01

    Full Text Available The aim of the study was to investigate the effect of different growth conditions on anthocyanins and flavonols accumulation in leaves of green and red loose leaf lettuce (Lactuca sativa var. crispa. Lettuce plants were grown in three types of conditions, in greenhouse (I. variant, behind clear glass in field (II. variant and in open field conditions (III. variant. Estimation of anthocyanins and flavonols content was done by non-destructive measurements with optical fluorescence sensor Multiplex® 3 (Force-A, France. It was estimated that green lettuce varieties had a greater flavonols content compared to red lettuce varieties in all experimental variants. The highest level of flavonols was detected in leaves of green variety Zoltán (1.218 RU and in red lettuce had the highest amount of flavonols in variety Carmesi (1.095 RU. At the same time red lettuce varieties were characterized by higher anthocyanins content. Parameter anthocyanin index is correlated with visible red coloration of leaves. The highest content of anthocyanins was detected in variety Oakly (0.867 RU. Under the open field conditions was found statistically significant higher (P < 0.05 flavonols and anthocyanins level in both green and red lettuce leaves compared to greenhouse conditions. It may be connected with intensification of flavonoids biosynthesis and accumulation which normally stimulated by sun irradiation, especially UV-B radiation.

  2. Neural Network Modeling to Predict Shelf Life of Greenhouse Lettuce

    Directory of Open Access Journals (Sweden)

    Wei-Chin Lin

    2009-04-01

    Full Text Available Greenhouse-grown butter lettuce (Lactuca sativa L. can potentially be stored for 21 days at constant 0°C. When storage temperature was increased to 5°C or 10°C, shelf life was shortened to 14 or 10 days, respectively, in our previous observations. Also, commercial shelf life of 7 to 10 days is common, due to postharvest temperature fluctuations. The objective of this study was to establish neural network (NN models to predict the remaining shelf life (RSL under fluctuating postharvest temperatures. A box of 12 - 24 lettuce heads constituted a sample unit. The end of the shelf life of each head was determined when it showed initial signs of decay or yellowing. Air temperatures inside a shipping box were recorded. Daily average temperatures in storage and averaged shelf life of each box were used as inputs, and the RSL was modeled as an output. An R2 of 0.57 could be observed when a simple NN structure was employed. Since the "future" (or remaining storage temperatures were unavailable at the time of making a prediction, a second NN model was introduced to accommodate a range of future temperatures and associated shelf lives. Using such 2-stage NN models, an R2 of 0.61 could be achieved for predicting RSL. This study indicated that NN modeling has potential for cold chain quality control and shelf life prediction.

  3. Carrot, Corn, Lettuce and Soybean Nutrient Contents are ...

    Science.gov (United States)

    Biochar, the carbon-rich material remaining after pyrolysis of cellulosic and manure feedstocks, has the potential as a soil amendment to sequester carbon and to improve soil water-holding and nutrient properties- thereby enhancing plant growth. However, biochar produced from some feedstocks also could adversely affect crop quality by changing soil pH and reducing nutrients (e.g., Ca, K, Mg, N, Na, and P) in plant tissues. To evaluate effects of biochar on the nutrient quality of four crops, we conducted a greenhouse study using pots with: carrot (Daucus carota cv. Tendersweet), corn (Zea mays, cv. Golden Bantam), lettuce (Lactuca sativa, cv. Black-Seeded Simpson) and soybean (Glycine max cv. Viking 2265). Plants were grown in one of two South Carolina sandy Coastal Plain soils (Norfolk and Coxville Soil Series), along with biochar (1% by weight) produced from pine chips (PC), poultry litter (PL), swine solids (SS), switchgrass (SG), and two blends of pine chips plus poultry litter (PC/PL, 50/50% and 80/20%). Each of the feedstocks and feedstock blends was pyrolyzed at 350, 500, and 700 ̊ C to produce the biochar used to amend the Norfolk and Coxville soils. Effects of biochar on leaf nutrients (% dry weight) statistically varied with species, soil, feedstock and temperature and nutrient. For carrot and lettuce, the PL, PL/PC, and SS biochars generally decreased leaf N, Ca, Mg, and P; while PL and PL/PC increased K and Na. Biochars had little effect on lea

  4. Mannanase production by the lettuce endosperm : Control by the embryo.

    Science.gov (United States)

    Halmer, P; Bewley, J D

    1979-01-01

    Endo-β-mannanase (EC 3.2.1.78) is produced and secreted by the cells of the endosperm of lettuce (lactuca sativa L.) "seeds" (achenes). In imbibed intact seeds, production is prevented by inhibitors. If the endosperm is incubated alone, these inhibitors can be removed by leaching, allowing mannanase production. Abscisic acid, a component of lettuce seeds, inhibits the production of mannanase in the isolated endosperm, and may be involved in regulation of mannanase production in intact seeds. During germination the inhibition is removed, beginning 4-8 h after red-light irradiation, which was given 4 h from sowing. The cotyledons participate in this process, and are controlled by events occuring in the axis within 4 h from red-light irradiation. This control by the axis apparently depends on the exchange of diffusible substances. Both benzyladenine and gibberellic acid can replace the influence of the axis if the latter is removed, and may therefore be involved in the control by the axis of the rest of the seed.

  5. Yield of lettuce grown in aquaponic system using different substrates

    Directory of Open Access Journals (Sweden)

    Rodrigo A. Jordan

    Full Text Available ABSTRACT In the aquaponic system, the characteristics of the materials used as substrate directly affect plant development, because besides acting as a support base, they must present a surface to fix microorganisms, responsible for the conversion of nutrients into forms more easily available to plants. Thus, the objective of this study was to evaluate the effect of four growing substrates on the yield of lettuce grown in aquaponic system. The experimental design was randomized blocks with four treatments, which corresponded to the substrates, and six replicates. Plants were grown using the nutrient film technique (NFT system. The substrates used in the experiment were: coconut shell fiber with crushed stone #3, expanded vermiculite, zeolite and phenolic foam. The treatment with phenolic foam was considered as the least suitable for lettuce cultivation in aquaponic system, because it caused lower yield (20.8 t ha-1. The treatment using coconut shell fiber with crushed stone #3 was considered as the most adequate, since it led to higher yield (39.9 t ha-1 compared with the other substrates analyzed.

  6. Impact of phytopathogen infection and extreme weather stress on internalization of Salmonella Typhimurium in lettuce.

    Science.gov (United States)

    Ge, Chongtao; Lee, Cheonghoon; Nangle, Ed; Li, Jianrong; Gardner, David; Kleinhenz, Matthew; Lee, Jiyoung

    2014-01-03

    Internalization of human pathogens, common in many types of fresh produce, is a threat to human health since the internalized pathogens cannot be fully inactivated/removed by washing with water or sanitizers. Given that pathogen internalization can be affected by many environmental factors, this study was conducted to investigate the influence of two types of plant stress on the internalization of Salmonella Typhimurium in iceberg lettuce during pre-harvest. The stresses were: abiotic (water stress induced by extreme weather events) and biotic (phytopathogen infection by lettuce mosaic virus [LMV]). Lettuce with and without LMV infection were purposefully contaminated with green fluorescence protein-labeled S. Typhimurium on the leaf surfaces. Lettuce was also subjected to water stress conditions (drought and storm) which were simulated by irrigating with different amounts of water. The internalized S. Typhimurium in the different parts of the lettuce were quantified by plate count and real-time quantitative PCR and confirmed with a laser scanning confocal microscope. Salmonella internalization occurred under the conditions outlined above; however internalization levels were not significantly affected by water stress alone. In contrast, the extent of culturable S. Typhimurium internalized in the leafy part of the lettuce decreased when infected with LMV under water stress conditions and contaminated with high levels of S. Typhimurium. On the other hand, LMV-infected lettuce showed a significant increase in the levels of culturable bacteria in the roots. In conclusion, internalization was observed under all experimental conditions when the lettuce surface was contaminated with S. Typhimurium. However, the extent of internalization was only affected by water stress when lettuce was infected with LMV. © 2013.

  7. pH dependent antioxidant activity of lettuce (L. sativa) and synergism with added phenolic antioxidants.

    Science.gov (United States)

    Altunkaya, Arzu; Gökmen, Vural; Skibsted, Leif H

    2016-01-01

    Influence of pH on the antioxidant activities of combinations of lettuce extract (LE) with quercetin (QC), green tea extract (GTE) or grape seed extract (GSE) was investigated for both reduction of Fremy's salt in aqueous solution using direct electron spin resonance (ESR) spectroscopy and in L-α-phosphatidylcholine liposome peroxidation assay measured following formation of conjugated dienes. All examined phenolic antioxidants showed increasing radical scavenging effect with increasing pH values by using both methods. QC, GTE and GSE acted synergistically in combination with LE against oxidation of peroxidating liposomes and with QC showing the largest effect. The pH dependent increase of the antioxidant activity of the phenols is due to an increase of their electron-donating ability upon deprotonation and to their stabilization in alkaline solutions leading to polymerization reaction. Such polymerization reactions of polyphenolic antioxidants can form new oxidizable -OH moieties in their polymeric products resulting in a higher radical scavenging activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Effect of electron beam irradiation on seed germination

    Energy Technology Data Exchange (ETDEWEB)

    Han, Seunghee; Bae, Youngmin [Changwon Univ., Changwon (Korea, Republic of)

    2013-07-01

    Effect of electron beam irradiation on seed germination was investigated in this research. Electron beam of 0.5, 1.0, 1.5 and 2.0 kGy was irradiated to the seeds of lettuce, green onion and cucumber, and the irradiated seeds were incubated at 25 .deg. Cn Nitsch medium solidified with 0.2% Phytagel. Germination percentage and the length of the sprouts were determined after 72 hours. Germination percentage of lettuce seeds was greatly reduced by the irradiation, and that of the green onion and cucumber were moderately reduced or unchanged by the irradiation. Although average length of the lettuce sprouts was reduced severely, that of the green onion and cucumber was unchanged or moderately reduced. Conclusively, electron beam irradiation might be a useful way of disinfecting some plant seeds including green onion and cucumber.

  9. Effect of electron beam irradiation on seed germination

    International Nuclear Information System (INIS)

    Han, Seunghee; Bae, Youngmin

    2013-01-01

    Effect of electron beam irradiation on seed germination was investigated in this research. Electron beam of 0.5, 1.0, 1.5 and 2.0 kGy was irradiated to the seeds of lettuce, green onion and cucumber, and the irradiated seeds were incubated at 25 .deg. Cn Nitsch medium solidified with 0.2% Phytagel. Germination percentage and the length of the sprouts were determined after 72 hours. Germination percentage of lettuce seeds was greatly reduced by the irradiation, and that of the green onion and cucumber were moderately reduced or unchanged by the irradiation. Although average length of the lettuce sprouts was reduced severely, that of the green onion and cucumber was unchanged or moderately reduced. Conclusively, electron beam irradiation might be a useful way of disinfecting some plant seeds including green onion and cucumber

  10. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  11. Phloem sap collection from lettuce (Lactuca sativa L.): Methodology and yield.

    Science.gov (United States)

    van Helden, M; Tjallingii, W F; van Beek, T A

    1994-12-01

    Three methods to collect phloem sap on different lettuce lines were optimized and are described in detail. The success ratio for stylectomy of aphids was over 80% through the combination of a specially designed setup and electrical penetration graphs to monitor phloem sap ingestion. For unknown reasons on some lettuce lines stylets never showed sustained exudation. There were clear differences in stylet exudation between two aphid species on the same lettuce line. Honeydew collection in hexadecane made accurate quantitative analysis possible; samples were large and clean, but biotransformed. The EDTA chelation method produced large samples, but dilution, oxidation, and impurities from the wound surface reduced the reliability.

  12. Persistence and Dissipation of Chlorpyrifos in Brassica Chinensis, Lettuce, Celery, Asparagus Lettuce, Eggplant, and Pepper in a Greenhouse

    Science.gov (United States)

    Lu, Meng-Xiao; Jiang, Wayne W.; Wang, Jia-Lei; Jian, Qiu; Shen, Yan; Liu, Xian-Jin; Yu, Xiang-Yang

    2014-01-01

    The residue behavior of chlorpyrifos, which is one of the extensively used insecticides all around the world, in six vegetable crops was assessed under greenhouse conditions. Each of the vegetables was subjected to a foliar treatment with chlorpyrifos. Two analytical methods were developed using gas chromatography equipped with a micro-ECD detector (LOQ = 0.05 mg kg−1) and liquid chromatography with a tandem mass spectrometry (LOQ = 0.01 mg kg−1). The initial foliar deposited concentration of chlorpyrifos (mg kg−1) on the six vegetables followed the increasing order of brassica chinensischlorpyrifos showed differences among the six selected vegetable plants, ranging from 16.5±0.9 mg kg−1 (brassica chinensis) to 74.0±5.9 mg kg−1 (pepper plant). At pre-harvest interval 21 days, the chlorpyrifos residues in edible parts of the crops were chlorpyrifos were found to be 7.79 (soil), 2.64 (pepper plants), 3.90 (asparagus lettuce), 3.92 (lettuce), 5.81 (brassica chinensis), 3.00 (eggplant plant), and 5.45 days (celery), respectively. The dissipation of chlorpyrifos in soil and the six selected plants was different, indicating that the persistence of chlorpyrifos residues strongly depends upon leaf characteristics of the selected vegetables. PMID:24967589

  13. Researches Regarding the Influence of Cold Storage on the Chlorophyll Content in Lettuce

    Directory of Open Access Journals (Sweden)

    Iuliana Cretescu

    2014-05-01

    Full Text Available The aim of the present investigations was to determine the effect of the cold storage period on the content of chlorophylls in the leaves of lettuce and arugula (rucola. The research material consisted in two types of lettuce (Lactuca sativa L. var. capitata; Lactuca sativa L. var. crispa and arugula (Eruca sativa purchased from supermarkets in Timisoara. The quantitative determination of chlorophyll pigments in leaves (SPAD was made by chlorophyll meter (SPAD 502 Konica-Minolta. During the few days cold storage at a temperature of 4ºC, the content of chlorophyll in the leaf significantly decreased, compared with that in the control group. After 3 days of cold storage arugula and lettuce (Lactuca sativa var. capitata values of chlorophyll content differ statistically very significantly (p<0.001 from the values found in the control group which for lettuce (Lactuca sativa L. var. crispa differs statistically significant (p < 0.05.

  14. Effect of Root-Zone Moisture Variations on Growth of Lettuce and Pea Plants

    Science.gov (United States)

    Ilieva, Iliana; Ivanova, Tania

    2008-06-01

    Variations in substrate moisture lead to changes in water and oxygen availability to plant roots. Ground experiments were carried out in the laboratory prototype of SVET-2 Space Greenhouse to study the effect of variation of root-zone moisture conditions on growth of lettuce and pea plants. The effect of transient increase (for 1 day) and drastic increase (waterlogging for 10 days) of substrate moisture was studied with 16-day old pea and 21-day old lettuce plants respectively. Pea height and fresh biomass accumulation were not affected by transient substrate moisture increase. Net photosynthetic rate (Pn) of pea plants showed fast response to substrate moisture variation, while chlorophyll content did not change. Drastic change of substrate moisture suppressed lettuce Pn, chlorophyll biosynthesis and plant growth. These parameters slowly recovered after termination of waterlogging treatment but lettuce yield was greatly affected. The results showed that the most sensitive physiological parameter to substrate moisture variations is photosynthesis.

  15. Series of Norovirus Outbreaks Caused by Consumption of Green Coral Lettuce, Denmark, April 2016

    DEFF Research Database (Denmark)

    Müller, Luise; Rasmussen, Lasse Dam; Jensen, Tenna

    2016-01-01

    In early April 2016, an unusual high number of point-source outbreaks of gastrointestinal disease were reported to occur in Denmark. Outbreaks were individually investigated. Two analytical studies were performed. Patient stool samples collected and analysed; positive stool samples were sequenced...... over the polymerase and/or capsid gene areas. Implicated lettuce heads were collected and analysed for the presence of norovirus. Foods were traced-back and traced-forward and international alert systems applied. A total of 23 linked point-source outbreaks occurred over the course of one week. Fresh...... green coral lettuce (Lollo Bionda lettuce) had been consumed in all settings. In a cohort study including 234 participants a dish containing green lettuce was associated with illness. Norovirus of Genogroup I (GI) was detected in samples from 28 patients comprising eight of the outbreaks. Sequencing...

  16. Experimental study and process parameters analysis on the vacuum cooling of iceberg lettuce

    International Nuclear Information System (INIS)

    He Suyan; Li Yunfei

    2008-01-01

    The vacuum cooling of iceberg lettuce was described in this paper. Based on the energy and mass balance, a mathematical model was developed to analyze the performance of the vacuum cooler and the evaporation-boiling phenomena during vacuum cooling of iceberg lettuce. The temporal trends of total system pressure, produce temperature such as surface temperature, center temperature, mass-average temperature, the weight loss of iceberg lettuce during vacuum cooling were predicted. Validation experimentation is achieved in the designed vacuum cooler. The experimental data were compared with the simulation results. It was found that the differences of the temperature between the simulation and the experiments were within 1 deg. C. The amount of water evaporated from the iceberg lettuce by simulation was 3.32% during the whole vacuum cooling, while the tested water loss rate was 2.97%, the maximal deviation of weight loss was within 0.59%. The simulation results agreed well with the experimental data

  17. Modeling Nitrogen Decrease in Water Lettuce Ponds from Waste Stabilization Ponds

    Science.gov (United States)

    Putri, Gitta Agnes; Sunarsih

    2018-02-01

    This paper presents about the dynamic modeling of the Water Lettuce ponds as a form of improvement from the Water Hyacinth ponds. The purpose of this paper is to predict nitrogen decrease and nitrogen transformation in Water Lettuce ponds integrated with Waste Stabilization Ponds. The model consists of 4 mass balances, namely Dissolved Organic Nitrogen (DON), Particulate Organic Nitrogen (PON), ammonium (NH4+), Nitrate and Nitrite (NOx). The process of nitrogen transformation which considered in a Water Lettuce ponds, namely hydrolysis, mineralization, nitrification, denitrification, plant and bacterial uptake processes. Numerical simulations are performed by giving the values of parameters and the initial values of nitrogen compounds based on a review of previous studies. Numerical results show that the rate of change in the concentration of nitrogen compounds in the integration ponds of waste stabilization and water lettuce decreases and reaches stable at different times.

  18. Mechanism of artemisinin phytotoxicity action: induction of reactive oxygen species and cell death in lettuce seedlings.

    Science.gov (United States)

    Yan, Zhi-Qiang; Wang, Dan-Dan; Ding, Lan; Cui, Hai-Yan; Jin, Hui; Yang, Xiao-Yan; Yang, Jian-She; Qin, Bo

    2015-03-01

    Artemisinin has been recognized as an allelochemical that inhibits growth of several plant species. However, its mode of action is not well clarified. In this study, the mechanism of artemisinin phytotoxicity on lettuce seedlings was investigated. Root and shoot elongation of lettuce seedlings were inhibited by artemisinin in a concentration-dependent manner. The compound effectively arrested cell division and caused loss of cell viability in root tips of lettuce. Overproduction of reactive oxygen species (ROS) was induced by artemisinin. Lipid peroxidation, proline overproduction and reduction of chlorophyll content in lettuce seedlings were found after treatments. These results suggested that artemisinin could induce ROS overproduction, which caused membrane lipids peroxidation and cell death, and impacted mitosis and physiological processes, resulting in growth inhibition of receptor plants. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  19. Round-robin comparison of methods for the detection of human enteric viruses in lettuce

    DEFF Research Database (Denmark)

    Le Guyader, Francoise S.; Schultz, Anna Charlotte; Haugarreau, Larissa

    2004-01-01

    Five methods that detect human enteric virus contamination in lettuce were compared. To mimic multiple contaminations as observed after sewage contamination, artificial contamination was with human calicivirus and poliovirus and animal calicivirus strains at different concentrations. Nucleic acid...

  20. Experimental study and process parameters analysis on the vacuum cooling of iceberg lettuce

    Energy Technology Data Exchange (ETDEWEB)

    He Suyan [School of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071 (China)], E-mail: hesuyan67829@sina.com; Li Yunfei [Department of Food Science and Engineering, School of Agriculture and Biology, Shanghai Jiao Tong University (China)

    2008-10-15

    The vacuum cooling of iceberg lettuce was described in this paper. Based on the energy and mass balance, a mathematical model was developed to analyze the performance of the vacuum cooler and the evaporation-boiling phenomena during vacuum cooling of iceberg lettuce. The temporal trends of total system pressure, produce temperature such as surface temperature, center temperature, mass-average temperature, the weight loss of iceberg lettuce during vacuum cooling were predicted. Validation experimentation is achieved in the designed vacuum cooler. The experimental data were compared with the simulation results. It was found that the differences of the temperature between the simulation and the experiments were within 1 deg. C. The amount of water evaporated from the iceberg lettuce by simulation was 3.32% during the whole vacuum cooling, while the tested water loss rate was 2.97%, the maximal deviation of weight loss was within 0.59%. The simulation results agreed well with the experimental data.

  1. Effect of 5-aminolevulinic acid on yield and quality of lettuce in sunlit ...

    African Journals Online (AJOL)

    ese

    2012-07-03

    Jul 3, 2012 ... Here, we report the effects of ALA on photosynthetic rate, yield and quality of lettuce in sunlit ... Plant growth regulators (PGRs) are widely applied on crops as a means of ..... This research was made possible by financial.

  2. Comparison of proteome response to saline and zinc stress in lettuce

    OpenAIRE

    Lucini, Luigi; Bernardo, Letizia

    2015-01-01

    Zinc salts occurring in soils can exert an osmotic stress toward plants. However, being zinc a heavy metal, some more specific effects on plant metabolisms can be forecast. In this work, lettuce has been used as a model to investigate salt and zinc stresses at proteome level through a shotgun tandem MS proteomic approach. The effect of zinc stress in lettuce, in comparison with NaCl stress, was evaluated to dissect between osmotic/oxidative stress related effects, from those changes specifica...

  3. The effect of growth conditions on flavonols and anthocyanins accumulation in green and red lettuce

    OpenAIRE

    Klaudia BRÜCKOVÁ; Oksana SYTAR; Marek ŢIVČÁK; Marian BRESTIC; Aleš LEBEDA

    2016-01-01

    The aim of the study was to investigate the effect of different growth conditions on anthocyanins and flavonols accumulation in leaves of green and red loose leaf lettuce (Lactuca sativa var. crispa). Lettuce plants were grown in three types of conditions, in greenhouse (I. variant), behind clear glass in field (II. variant) and in open field conditions (III. variant). Estimation of anthocyanins and flavonols content was done by non-destructive measurements with optical fluorescence sensor Mu...

  4. Antioxidant capacity and contents of phenols, ascorbic acid, β-carotene and lycopene in lettuce

    OpenAIRE

    Zdravković Jasmina M.; Aćamović-Đoković Gordana S.; Mladenović Jelena D.; Pavlović Radoš M.; Zdravković Milan S.

    2014-01-01

    The antioxidant activity of three lettuce varieties (Lactuca sativa L.) Emerald, Vera and Neva, cultivated in two kinds of protected spaces, a glasshouse and a plastic greenhouse, under controlled conditions, was determined. The content of antioxidant compounds: total phenols, flavonoids, L-ascorbic acid, ß-carotene and lycopene, were determined in ethanolic extracts of the lettuce with spectrophotometric methods. The largest content of total phenols (78.98...

  5. Effects of composted tobacco waste and farmyard manure on some soil physical properties and lettuce yield

    OpenAIRE

    Çerçioğlu, Melis; Okur, Bülent; Delibacak, Sezai; Ongun, Ali Rıza

    2008-01-01

    This research was held in Agriculture Faculty of Ege University Menemen Investigation and Practise Farmyard. Tobacco waste gathered from cigarette industry were composted and applied to the soil together with farmyard manure. lettuce (Lactuca sativa L. var. capitata) was grown as test plant. No mineral fertilizers or pestisides were applied. The effects of composted tobacco wastes and farmyard manures on soil physical properties and lettuce yield were investigated. All application...

  6. The economics of managing Verticillium wilt, an imported disease in California lettuce

    OpenAIRE

    Carroll, Christine L; Carter, Colin A; Goodhue, Rachael E; Lin Lawell, C.-Y. Cynthia; Subbarao, Krishna V

    2017-01-01

    Verticillium dahliae is a soilborne fungus that is introduced to the soil via infested spinach seeds and that causes lettuce to be afflicted with Verticillium wilt. This disease has spread rapidly through the Salinas Valley, the prime lettuce production region of California. Verticillium wilt can be prevented or controlled by the grower by fumigating, planting broccoli, or not planting spinach. Because these control options require long-term investment for future gain, renters might not take ...

  7. Effects of long-term low atmospheric pressure on gas exchange and growth of lettuce

    Science.gov (United States)

    Tang, Yongkang; Guo, Shuangsheng; Dong, Wenping; Qin, Lifeng; Ai, Weidang; Lin, Shan

    2010-09-01

    The objectives of this research were to determine photosynthesis, evapotranspiration and growth of lettuce at long-term low atmospheric pressure. Lettuce ( Lactuca sativa L . cv. Youmaicai) plants were grown at 40 kPa total pressure (8.4 kPa p) or 101 kPa total pressure (20.9 kPa p) from seed to harvest for 35 days. Germination rate of lettuce seeds decreased by 7.6% at low pressure, although this was not significant. There was no significant difference in crop photosynthetic rate between hypobaria and ambient pressure during the 35-day study. The crop evapotranspiration rate was significantly lower at low pressure than that at ambient pressure from 20 to 30 days after planting (DAP), but it had no significant difference before 20 DAP or after 30 DAP. The growth cycle of lettuce plants at low pressure was delayed. At low pressure, lettuce leaves were curly at the seedling stage and this disappeared gradually as the plants grew. Ambient lettuce plants were yellow and had an epinastic growth at harvest. The shoot height, leaf number, leaf length and shoot/root ratio were lower at low pressure than those at ambient pressure, while leaf area and root growth increased. Total biomass of lettuce plants grown at two pressures had no significant difference. Ethylene production at low pressure decreased significantly by 38.8% compared with ambient pressure. There was no significant difference in microelements, nutritional phytochemicals and nitrate concentrations at the two treatments. This research shows that lettuce can be grown at long-term low pressure (40 kPa) without significant adverse effects on seed germination, gas exchange and plant growth. Furthermore, ethylene release was reduced in hypobaria.

  8. The Comparison of Ammonium or Nitrate-Grown Lettuce and Spinach in a Hydroponic System

    OpenAIRE

    H. R. Roosta

    2010-01-01

    Most plant species are sensitive to high ammonium concentrations. In this experiment the sensitivity of lettuce and spinach to ammonium was investigated. In a factorial experiment with framework of a completely randomized design with two factors, nitrogen form (ammonium and nitrate) and plant species (lettuce and spinach), and three replications seeds were germinated in a mixture of perlite, sand and clay in soil-maid pots. After two weeks, the seedlings at two true-leaf stage were then trans...

  9. Diminished UV-absorbing nets reduce the Spreads and population density of Macrosiphum euphorbiae in lettuce.

    OpenAIRE

    Legarrea, S.; Díaz, B. M.; Plaza, M.; Barrios, L.; Morales, Ignacio; Viñuela Sandoval, Elisa; Fereres Castiel, Alberto

    2012-01-01

    UV-absorbing covers reduce the incidence of injurious insect pests and viruses in protected crops. In the present study, the effect of a UV-absorbing net (Bionet) on the spatio-temporal dynamics of the potato aphid on lettuce plants was evaluated. A field experiment was conducted during three seasons in two identical tunnels divided in four plots. A set of lettuce plants were artificially infested with Macrosiphum euphorbiae adults and the population was estimated by counting aphids on ev...

  10. Evaluation of three biostimulants in lettuce under parcel conditions

    Directory of Open Access Journals (Sweden)

    María Caridad Jiménez Arteaga

    2016-02-01

    Full Text Available The work was developed in the parcel Ñico López. The valued cultivation was the lettuce variety Black simpson, with the objective of evaluating the goods of three (3 bioestimulantes (Biobras 16, Biobras plus and Quitosana, about the yield and quality of the crop. The biostimulants was applied, to three stonemasons (one for biostimulant to the six days after transplant (DDT and three parcel to the seven DDT, leaving one stonemasons that as control, for an total seven (7 treatments. The main components of yield were measured and some components of the quality of the plant were determined in the Soils Province Laboratory The data were processed by the statistical package of the Statitic version 8 on Windows. One could observe that the three biostimulants has an effect positive on the mass and quality of the studied crop.

  11. Changes during imbition of irradiated dry seeds of lettuce

    International Nuclear Information System (INIS)

    Smith, M.T.

    1981-01-01

    Since ionizing radiation has been shown to produce free-radicals in dry seeds, effect peroxidation of lipids in model systems, and cause changes in membrane permeability, it was decided to subject dry seeds of lettuce to gamma irradiation to determine whether the cytological changes which occurred on subsequent imbition are similar in any way to those occurring during natural ageing in dry storage. Seeds of 3% moisture content were radiated with gamma rays from a Cobalt 60 source at doses between 3,4 kGy and 23,8 kGy and the root tips prepared for TEM after 5 and 12 hours imbition. The cytological changes which occurred are shortly discussed

  12. Use of Propolis in the Sanitization of Lettuce

    Directory of Open Access Journals (Sweden)

    Xesús Feás

    2014-07-01

    Full Text Available The present study aimed to determine the effectiveness of propolis in reducing the microbial load in ready-to-eat (RTE and fresh whole head (FWH lettuces (Lactuca sativa L. type Batavia. Two sanitizing solutions were employed: sodium hypochlorite (SH and propolis (PS, during 15 and 30 min. Tap water (TW was used as a control. Regarding the mean reduction on aerobic mesophiles, psychrotrophic and fecal coliforms, the SH and PS treatments showed the same pattern of variation. In all cases, PS was slightly more effective in the microbiological reduction in comparison with commercial SH. Reductions between two and three log cycles were obtained with PS on aerobic mesophiles and psychrotrophic counts. The information obtained in the present study can be used to evaluate the potential use of propolis as product for sanitizing other vegetables and for developing other food preservation technologies, with impact on human health.

  13. Changes during imbition of irradiated dry seeds of lettuce

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M T [Natal Univ., Durban (South Africa). Dept. of Biological Sciences

    1981-01-01

    Since ionizing radiation has been shown to produce free-radicals in dry seeds, effect peroxidation of lipids in model systems, and cause changes in membrane permeability, it was decided to subject dry seeds of lettuce to gamma irradiation to determine whether the cytological changes which occurred on subsequent imbition are similar in any way to those occurring during natural ageing in dry storage. Seeds of 3% moisture content were radiated with gamma rays from a Cobalt 60 source at doses between 3,4 kGy and 23,8 kGy and the root tips prepared for TEM after 5 and 12 hours imbition. The cytological changes which occurred are shortly discussed.

  14. Radiotracer studies of maneb residues in lettuce plants

    International Nuclear Information System (INIS)

    Sennaoui, Z.; Meguenni, H.; Bennaceur, M.

    1990-11-01

    Lettuce plants have received different treatments of 14C-maneb at variable time. A cleaning is made to determine the foliar surface residues. The analysis of CS2 showed relatively important amount especially for lots which have received 4 treatments (10,3ppm and 6,49ppm). The amounts found after combustion have showed increasing amounts, proportionally to the number of treatments. The analysis of ETU revealed a presence only for lots which have received several treatments (3 and 4). The analysis by TLC showed many metabolites. Two of them have been identified (ETU, EU). Interfoliar migration of 14C product occurred between treated leaves and untreated leaves of the same plant

  15. Laboratory and semi-field evaluation of Beauveria bassiana (Ascomycota: Hypocreales) against the lettuce aphid, Nasonovia ribisnigri (Hemiptera: Aphididae)

    DEFF Research Database (Denmark)

    Shrestha, Govinda; Enkegaard, Annie; Steenberg, Tove

    2015-01-01

    The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. The entomopathogenic fungus Beauveria bassiana strain GHA has recently been reported as a potential biocontrol candidate for use against the lettuce aphid. This study provides information...... on the mortality inflicted by B. bassiana when applied against different life stages of the lettuce aphid under laboratory conditions and how fungus infection affects the aphid fecundity. In addition, temporal changes in persistence of fungus inoculum applied to foliage of young lettuce plants under semi......-field conditions was analysed. Immature life stages were generally the least susceptible to fungal infection and the susceptibility of all stages was dose-dependent, with the highest mortality occurring at the highest dose. B. bassiana significantly affected the rate of nymph production by the lettuce aphid...

  16. High-level transient expression of recombinant protein in lettuce.

    Science.gov (United States)

    Joh, Lawrence D; Wroblewski, Tadeusz; Ewing, Nicholas N; VanderGheynst, Jean S

    2005-09-30

    Transient expression following agroinfiltration of plant tissue was investigated as a system for producing recombinant protein. As a model system, Agrobacterium tumefaciens containing the beta-glucuronidase (GUS) gene was vacuum infiltrated into lettuce leaf disks. Infiltration with a suspension of 10(9) colony forming units/mL followed by incubation for 72 h at 22 degrees C in continuous darkness produced a maximum of 0.16% GUS protein based on dry tissue or 1.1% GUS protein based on total soluble protein. This compares favorably to expression levels for commercially manufactured GUS protein from transgenic corn seeds. A. tumefaciens culture medium pH between 5.6 and 7.0 and surfactant concentrations lettuce to produce GUS protein more rapidly, but final levels did not exceed the GUS production in leaves incubated in continuous darkness after 72 h at 22 degrees C. The kinetics of GUS expression during incubation in continuous light and dark were represented well using a logistic model, with rate constants of 0.30 and 0.29/h, respectively. To semi-quantitatively measure the GUS expression in large numbers of leaf disks, a photometric enhancement of the standard histochemical staining method was developed. A linear relationship with an R2 value of 0.90 was determined between log10 (% leaf darkness) versus log10 (GUS activity). Although variability in expression level was observed, agroinfiltration appears to be a promising technology that could potentially be scaled up to produce high-value recombinant proteins in planta. Copyright 2005 Wiley Periodicals, Inc

  17. Non-destructive prediction of pigment content in lettuce based on visible-NIR spectroscopy.

    Science.gov (United States)

    Steidle Neto, Antonio José; Moura, Lorena de Oliveira; Lopes, Daniela de Carvalho; Carlos, Lanamar de Almeida; Martins, Luma Moreira; Ferraz, Leila de Castro Louback

    2017-05-01

    Lettuce (Lactuca sativa L.) is one of the most important salad vegetables in the world, with a number of head shapes, leaf types and colors. The lettuce pigments play important physiological functions, such as photosynthetic processes and light stress defense, but they also benefit human health because of their antioxidant action and anticarcinogenic properties. In this study three lettuce cultivars were grown under different farming systems, and partial least squares models were built to predict the leaf chlorophyll, carotenoid and anthocyanin content. The three proposed models resulted in high coefficients of determination and variable importance for the projection values, as well as low estimative errors for calibration and external validation datasets. These results confirmed that it is possible to accurately predict chlorophyll, carotenoid and anthocyanin content of green and red lettuces, grown in different farming systems, based on the spectral reflectance from 500 to 1000 nm. The proposed models were adequate for estimating lettuce pigments in a quick and non-destructive way, representing an alternative to conventional measurement methods. Prediction accuracies were improved by using the detrending, smoothing and first derivative pretreatments to the original spectral signatures prior to estimating lettuce chlorophyll, carotenoid and anthocyanin content, respectively. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  18. Purification and Characterization of Polyphenol Oxidase, Peroxidase and Lipoxygenase from Freshly Cut Lettuce (L. sativa

    Directory of Open Access Journals (Sweden)

    Vural Gökmen

    2011-01-01

    Full Text Available Enzymatic reactions taking place in minimally processed vegetables are considered as a major problem, because they adversely affect sensorial and nutritional quality. Polyphenol oxidase (PPO, peroxidase (POD and lipoxygenase (LOX from lettuce were purified on a column packed with positively charged diethylaminoethyl (DEAE cellulose by applying pH gradient elution from pH=4.0 to 9.0. The main purified fractions (PPO1 and PPO4, POD1 and POD2, LOX1 and LOX2 were characterized for enzyme concentration-reaction rate relationship, thermal stability, pH activity and kinetic parameters. Kinetic properties of each isoform were considerably different. Cysteine was found as the most effective inhibitor of both fractions of PPO. Kinetic parameters of lettuce POD were presented using guaiacol at various H2O2 concentrations. β-carotene directly influences lettuce LOX in the reaction medium available for the catalytic conversion of linoleic acid into hydroperoxides. Ascorbic and oxalic acids appear as effective PPO inhibitors, protecting phenolic compounds against oxidation in lettuce. Understanding the characteristics of deteriorative enzymes becomes important to maintain suitable conditions for fresh-like quality of lettuce. The results can be useful to keep the nutritional quality of minimally processed lettuce during shelf-life.

  19. Determination of Profenofos Pesticidal Residue in Lettuce (Lactuca sativa L. by Gas Chromatographic Method

    Directory of Open Access Journals (Sweden)

    Yohannes Alen

    2015-05-01

    Full Text Available The determination of profenofos pesticidal residue in the lettuce (Lactuca sativa L. by using gas chromatography using flame photometric detector (FPD had been investigated. The lettuce was collected from Padang Luar area, Agam distric, West Sumatera. Sample for determination of profenofos residue divided into three groups: unwashed (A, washed with water (B, and washed with detergent (C. Maceration with sonication was used for the extraction using ethylacetateas a solvent. The results showed that profenofos pesticide residue in sample A, B and C were 0.204, 0.080 and 0.061 ppm, respectively. These profenofos pesticidal residue are over than the Maximum Residue Limits (MRL that established by The Japan Food Chemical Research Foundation (0.05 ppm even though World Health Organization (WHO has not established Maximum Residue Limits (MRL profenofos on lettuce. Based on the statistical analysis one-way method (Anova using SPSS 20.0 showed that there was a significant concentrations difference between lettuce A from lettuce B and lettuce C with p < 0.05.

  20. Uptake and Accumulation of Pharmaceuticals in Lettuce Under Surface and Overhead Irrigations

    Science.gov (United States)

    Bhalsod, G.; Chuang, Y. H.; Jeon, S.; Gui, W.; Li, H.; Guber, A.; Zhang, W.

    2015-12-01

    Pharmaceuticals and personal care products are being widely detected in wastewater and surface waters. As fresh water becomes scarcer, interests in using reclaimed water for crop irrigation is intensified. Since reclaimed waters often carry trace levels of pharmaceuticals, accumulation of pharmaceuticals in food crops could increase the risk of human exposure. This study aims to investigate uptake and accumulations of pharmaceuticals in greenhouse-grown lettuce under contrasting irrigation practices (i.e., overhead and surface irrigations). Lettuce was irrigated with water spiked with 11 commonly used pharmaceuticals (acetaminophen, caffeine, carbamazepine, sulfadiazine, sulfamethoxazole, carbadox, trimethoprim, lincomycin hydrochloride, oxytetracycline hydrochloride, monensin sodium, and tylosin). Weekly sampling of lettuce roots, shoots, and soils were continued for 5 weeks, and the samples were freeze dried, extracted for pharmaceuticals and analyzed by LC-MS/MS. Preliminary results indicate that higher concentrations of pharmaceuticals were found in overhead irrigated lettuce compared to surface irrigated lettuce. For carbamezapine, sulfadiazine, trimethoprim, oxytetracycline, and monensin sodium, their concentrations generally increased in lettuce shoots in the overhead treatment over time. However, acetaminophen was found at higher concentrations in both shoots and roots, indicating that acetaminophen can be easily transported in the plant system. This study provides insight on developing better strategies for using reclaimed water for crop irrigations, while minimizing the potential risks of pharmaceutical contamination of vegetables.

  1. Evaluation of Lettuce Germplasm Resistance to Gray Mold Disease for Organic Cultivations

    Directory of Open Access Journals (Sweden)

    Chang Ki Shim

    2014-03-01

    Full Text Available This study was conducted to evaluate the resistance of 212 accessions of lettuce germplasm to gray mold disease caused by Botrytis cinerea. The lettuce germplasm were composed of five species: Lactuca sativa (193 accessions, L. sativa var. longifolia (2 accessions, L. sativa var. crispa (2 accessions, L. saligna (2 accessions, and L. serriola (1 accession; majority of these originated from Korea, Netherlands, USA, Russia, and Bulgaria. After 35 days of spray inoculation with conidial suspension (3×10⁷ conidia/ml of B. cinerea on the surface of lettuce leaves, tested lettuce germplasm showed severe symptoms of gray mold disease. There were 208 susceptible accessions to B. cinerea counted with 100% of disease incidence and four resistant accessions, IT908801, K000598, K000599, and K021055. Two moderately resistant accessions of L. sativa, K021055 and IT908801, showed 20% of disease incidence of gray mold disease at 45 days after inoculation; and two accessions of L. saligna, K000598 and K000599, which are wild relatives of lettuce germplasm with loose-leaf type, showed complete resistance to B. cinerea. These four accessions are candidates for breeding lettuce cultivars resistant to gray mold disease.

  2. Arsenic uptake by lettuce from As-contaminated soil remediated with Pteris vittata and organic amendment.

    Science.gov (United States)

    de Oliveira, Letuzia M; Suchismita, Das; Gress, Julia; Rathinasabapathi, Bala; Chen, Yanshan; Ma, Lena Q

    2017-06-01

    Leaching of inorganic arsenic (As) from chromated copper arsenate (CCA)-treated wood may elevate soil As levels. Thus, an environmental concern arises regarding As accumulation in vegetables grown in these soils. In this study, a greenhouse experiment was conducted to investigate the ability of As-hyperaccumulator P. vittata and organic amendments in reducing As uptake by lettuce (Lactuca sativa) from a soil contaminated from CCA-treated wood (63.9 mg kg -1 As). P. vittata was grown for 150 d in a CCA-contaminated soil amended with biochar, activated carbon or coffee grounds at 1%, followed by lettuce for another 55 d. After harvest, plant biomass and As concentrations in plant and soil were determined. The presence of P. vittata reduced As content in lettuce by 21% from 27.3 to 21.5 mg kg -1 while amendment further reduced As in lettuce by 5.6-18%, with activated C being most effective. Our data showed that both P. vittata and organic amendments were effective in reducing As concentration in lettuce. Though no health-based standard for As in vegetables exists in USA, care should be taken when growing lettuce in contaminated soils. Our data showed that application of organic amendments with P. vittata reduced As hazards in CCA-contaminated soils. Published by Elsevier Ltd.

  3. Responses of Nasonovia ribisnigri (Homoptera: Aphididae) to susceptible and resistant lettuce.

    Science.gov (United States)

    Liu, Yong-Biao; McCreight, James D

    2006-06-01

    Nymphs and alates of aphid Nasonovia ribisnigri (Mosley) (Homoptera: Aphididae) were tested on 10 lettuce cultivars with N. ribisnigri resistance gene Nr and 18 cultivars without the resistance gene in various bioassays. Bioassays used whole plants, leaf discs, or leaf cages to determine susceptibility of commercial lettuce cultivars to N. ribisnigri infestation and to evaluate screening methods for breeding lettuce resistance to N. ribisnigri. Resistant and susceptible plants were separated in 3 d when using whole plant bioassays. Long-term (> or =7 d) no-choice tests using leaf cages or whole plants resulted in no survival of N. ribisnigri on resistant plants, indicating great promise of the Nr gene for management of N. ribisnigri. Effective screening was achieved in both no-choice tests where resistant or susceptible intact plants were tested separately in groups or individually and in choice tests where susceptible and resistant plants were intermixed. Leaf discs bioassays were not suitable for resistance screening. All lettuce cultivars without the resistance gene were suitable hosts for N. ribisnigri, indicating the great importance of this pest to lettuce production and the urgency in developing resistant lettuce cultivars to manage N. ribisnigri.

  4. Ultralow oxygen treatment for postharvest control of Nasonovia ribisnigri (Homoptera: Aphididae) on iceberg lettuce.

    Science.gov (United States)

    Liu, Yong-Biao

    2005-12-01

    The aphid Nasonovia ribisnigri (Mosley) is a common pest of lettuce in the United States. It hinders export of U.S. lettuce to the overseas market such as Japan where it is a quarantined pest. Ultralow oxygen treatments were studied for control of the insect on iceberg lettuce. Small-scale ultralow oxygen treatments in plastic jars were conducted at 1, 5, and 10 degrees C for different durations to determine effective treatment against nymphs and alates of N. ribisnigri. At oxygen levels of 0.015-0.025%, N. ribisnigri can be controlled in 3 d at 1 degrees C, 2 d at 5 degrees C, and 1 d at 10 degrees C. Large-scale ultralow oxygen treatments were conducted in bulk container treatment chambers with commercial iceberg lettuce heads for 2 d at 6 degrees C with oxygen levels of 0.015 and 0.025% and for 3 d at 3 degrees C with oxygen level of 0.015%. All treatments achieved complete control of N. ribisnigri. No negative impact on lettuce quality was detected after 2 wk of posttreatment storage. Therefore, the selected treatments have potential to be commercially developed for postharvest control of N. ribisnigri on iceberg lettuce.

  5. Bacterial diversity and community structure in lettuce soil are shifted by cultivation time

    Science.gov (United States)

    Liu, Yiqian; Chang, Qing; Guo, Xu; Yi, Xinxin

    2017-08-01

    Compared with cereal production, vegetable production usually requires a greater degree of management and larger input of nutrients and irrigation, but these systems are not sustainable in the long term. This study aimed to what extent lettuce determine the bacterial community composition in the soil, during lettuce cultivation, pesticides and fertilizers were not apply to soil. Soil samples were collected from depths of 0-20cm and 20-40cm. A highthroughput sequencing approach was employed to investigate bacterial communities in lettuce-cultivated soil samples in a time-dependent manner. The dominant bacteria in the lettuce soil samples were mainly Proteobacteria, Actinobacteria, Chloroflexi, Nitrospirae, Firmicutes, Acidobacteria, Bacteroidetes, Verrucomicrobia, Planctomycetes, Gemmatimo nadetes, Cyanobacteria. Proteobacteria was the most abundant phylum in the 6 soil samples. The relative abundance of Acidobacteria, Firmicutes, Bacteroidetes, Verrucomicrobia and Cyanobacteria decreased through time of lettuce cultivation, but the relative abundance of Proteobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi, Planctomycetes and Nitrospirae increased over time. In the 0-20cm depth group and the 20-40cm depth soil, a similar pattern was observed that the percentage number of only shared OTUs between the early and late stage was lower than that between the early and middle stage soil, the result showed that lettuce growth can affect structure of soil bacterial communities.

  6. Uptake of perfluorinated alkyl acids by hydroponically grown lettuce (Lactuca sativa).

    Science.gov (United States)

    Felizeter, Sebastian; McLachlan, Michael S; de Voogt, Pim

    2012-11-06

    An uptake study was carried out to assess the potential human exposure to perfluorinated alkyl acids (PFAAs) through the ingestion of vegetables. Lettuce (Lactuca sativa) was grown in PFAA-spiked nutrient solutions at four different concentrations, ranging from 10 ng/L to 10 μg/L. Eleven perfluorinated carboxylic acids (PFCAs) and three perfluorinated sulfonic acids (PFSAs) were analyzed by HPLC-MS/MS. At the end of the experiment, the major part of the total mass of each of the PFAAs (except the short-chain, C4-C7, PFCAs) taken up by plants appeared to be retained in the nonedible part, viz. the roots. Root concentration factors (RCF), foliage/root concentration factors (FRCF), and transpiration stream concentration factors (TSCF) were calculated. For the long chained PFAAs, RCF values were highest, whereas FRCF were lowest. This indicates that uptake by roots is likely governed by sorption of PFAAs to lipid-rich root solids. Translocation from roots to shoots is restricted and highly depending on the hydrophobicity of the compounds. Although the TSCF show that longer-chain PFCAs (e.g., perfluorododecanoic acid) get better transferred from the nutrient solution to the foliage than shorter-chain PFCAs (e.g., perfluoroheptanoic acid), the major fraction of longer-chain PFCAs is found in roots due to additional adsorption from the spiked solution. Due to the strong electron-withdrawing effect of the fluorine atoms the role of the negative charge of the dissociated PFAAs is likely insignificant.

  7. Lytic bacteriophages reduce Escherichia coli O157: H7 on fresh cut lettuce introduced through cross-contamination.

    Science.gov (United States)

    Ferguson, Sean; Roberts, Cheryl; Handy, Eric; Sharma, Manan

    2013-01-01

    The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli O157:H7 (4.10 CFU/cm 2 ) following exposure to 50 μg/ml chlorine for 30 sec. After immersion studies, lettuce was spot-inoculated with E. coli O157:H7 (2.38 CFU/cm 2 ). Phage-treated, inoculated lettuce pieces were stored at 4°C for and analyzed for E. coli O157:H7 populations for up to 7 d. Immersion of lettuce in 9.8 log PFU/ml EcoShield™ for 2 min significantly (p PFU/ml) resulted in the deposition of high concentrations (7.8 log log PFU/cm 2 ) of bacteriophages on the surface of fresh cut lettuce, potentially contributing to the efficacy of the lytic phages on lettuce. Spraying phages on to inoculated fresh cut lettuce after being washed in hypochlorite solution was significantly more effective in reducing E. coli O157:H7 populations (2.22 log CFU/cm 2 ) on day 0 compared with control treatments (4.10 log CFU/cm 2 ). Both immersion and spray treatments provided protection from E. coli O157:H7 contamination on lettuce, but spray application of lytic bacteriophages to lettuce was more effective in immediately reducing E. coli O157:H7 populations fresh cut lettuce.

  8. Microbial risk in wastewater irrigated lettuce: comparing Escherichia coli contamination from an experimental site with a laboratory approach.

    Science.gov (United States)

    Makkaew, P; Miller, M; Fallowfield, H J; Cromar, N J

    This study assessed the contamination of Escherichia coli, in lettuce grown with treated domestic wastewater in four different irrigation configurations: open spray, spray under plastic sheet cover, open drip and drip under plastic sheet cover. Samples of lettuce from each irrigation configuration and irrigating wastewater were collected during the growing season. No E. coli was detected in lettuce from drip irrigated beds. All lettuce samples from spray beds were positive for E. coli, however, no statistical difference (p > 0.05) was detected between lettuces grown in open spray or covered spray beds. The results from the field experiment were also compared to a laboratory experiment which used submersion of lettuce in wastewater of known E. coli concentration as a surrogate method to assess contamination following irrigation. The microbial quality of spray bed lettuces was not significantly different from submersed lettuce when irrigated with wastewater containing 1,299.7 E. coli MPN/100 mL (p > 0.05). This study is significant since it is the first to validate that the microbial contamination of lettuce irrigated with wastewater in the field is comparable with a laboratory technique frequently applied in the quantitative microbial risk assessment of the consumption of wastewater irrigated salad crops.

  9. Phosphate effect on the content of selected elements in a lettuce variety grown at a contaminated soil

    International Nuclear Information System (INIS)

    Armelin, M.J.A.; Saiki, M.; Maihara, V.A.; Moreira, E.G.; Trevizam, A.R.; Muraoka, T.; Silva, M.L.S.

    2014-01-01

    The purpose of this study was to evaluate the efficiency of superphosphate fertilizer in remediating a contaminated soil with potentially toxic elements. For this, different phosphorus doses were used in a number of lettuce plants. The element concentrations determined in their leaves were compared with those found in control lettuce plants. Instrumental neutron activation analysis was the analytical technique used to determine element concentration in lettuce leave samples. The application of 250 mg kg -1 of P was the most effective treatment to reduce the concentrations of Br, Ca, Cd, Cl, Co, Cr, Fe, K, Mg, Mn, Sb and Zn in lettuce leaves. (author)

  10. Cross contamination of Escherichia coli O157:H7 between lettuce and wash water during home-scale washing.

    Science.gov (United States)

    Jensen, Dane A; Friedrich, Loretta M; Harris, Linda J; Danyluk, Michelle D; Schaffner, Donald W

    2015-04-01

    Lettuce and leafy greens have been implicated in multiple foodborne disease outbreaks. This study quantifies cross contamination between lettuce pieces in a small-scale home environment. A five-strain cocktail of relevant Escherichia coli O157:H7 strains was used. Bacterial transfer between single inoculated lettuce leaf pieces to 10 non-inoculated lettuce leaf pieces that were washed in a stainless steel bowl of water for 30 s, 1 min, 2 min, and 5 min was quantified. Regardless of washing time, the wash water became contaminated with 90-99% of bacteria originally present on the inoculated lettuce leaf piece. The E. coli O157:H7 concentration on initially inoculated leaf pieces was reduced ∼ 2 log CFU. Each initially uncontaminated lettuce leaf piece had ∼ 1% of the E. coli O157:H7 from the inoculated lettuce piece transferred to it after washing, with more transfer occurring during the shortest (30 s) and longest (5 min) wash times. In all cases the log percent transfer rates were essentially normally distributed. In all scenarios, most of the E. coli O157:H7 (90-99%) transferred from the inoculated lettuce pieces to the wash water. Washing with plain tap water reduces levels of E. coli O157:H7 on the inoculated lettuce leaf pieces, but also spreads contamination to previously uncontaminated leaf pieces. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Scientific rationale for cos lettuce growing technology Lactuca sativa var. longifolia L. in the Forest-Steppe of Ukraine

    Directory of Open Access Journals (Sweden)

    Н. В. Лещук

    2014-04-01

    Full Text Available Scientifically validated items of growing technology disclosed for cos lettuce marketable products in the conditions of Forest-Steppe of Ukraine. Impact of environmental factors onto growth and development of Lactuca sativa var. longifolia L. plants. Sowing terms established for the seed of cos lettuce at field-seeded growing. Development parameters are quoted for plant productivity indices and marketable product indices for cos lettuce of national and foreign breeding. According to VCU characteristics a  typical model has been designed for the cos lettuce indices of suitability for dissemination in Ukraine.

  12. Postharvest transfer and survival of Salmonella enterica serotype enteritidis on living lettuce.

    Science.gov (United States)

    Waitt, J A; Kuhn, D D; Welbaum, G E; Ponder, M A

    2014-02-01

    The potential for postharvest transfer of Salmonella to 'living lettuce' is not well understood. In this study, the transfer of Salmonella enterica Enteritidis (6 log CFU g(-1) ) from worker hands or contaminated roots to leaves of living lettuce was quantified. Transfer rates of Salmonella from contaminated gloves to sequentially handled lettuce heads ranged from 94% to head 1, 82% to head 2 and 69% to head 3. On average, 2.9 ± 0.1 log CFU g(-1) (64%) Salmonella was transferred from inoculated roots to leaves resulting from typical postharvest handling activities for living lettuce. Salmonella persisted on leaves stored at recommended storage temperatures (4°C) and increased 0.5 log CFU g(-1) when stored at temperature abuse conditions (12°C). Salmonella increased 1.6 log CFU g(-1) on roots after 18-day storage at 12°C, emphasizing the need to maintain temperature control to reduce the risk of human illness. Hydroponically grown lettuce packaged in plastic clamshells with intact roots, marketed as 'living lettuce', is increasing in popularity due to its extended shelf life. This study demonstrates the transfer of Salmonella from contaminated worker hands and contaminated roots to leaves where it persisted at 4°C for 18 day. Temperature abuse (12°C) increased Salmonella on roots and leaves. These findings suggest that failure to maintain temperatures below 12°C can pose a risk for consumers purchasing living lettuce at markets where recommended storage temperatures are not maintained. © 2013 The Society for Applied Microbiology.

  13. A PCR procedure for the detection of Giardia intestinalis cysts and Escherichia coli in lettuce.

    Science.gov (United States)

    Ramirez-Martinez, M L; Olmos-Ortiz, L M; Barajas-Mendiola, M A; Giono Cerezo, S; Avila, E E; Cuellar-Mata, P

    2015-06-01

    Giardia intestinalis is a pathogen associated with foodborne outbreaks and Escherichia coli is commonly used as a marker of faecal contamination. Implementation of routine identification methods of G. intestinalis is difficult for the analysis of vegetables and the microbiological detection of E. coli requires several days. This study proposes a PCR-based assay for the detection of E. coli and G. intestinalis cysts using crude DNA isolated from artificially contaminated lettuce. The G. intestinalis and E. coli PCR assays targeted the β-giardin and uidA genes, respectively, and were 100% specific. Forty lettuces from local markets were analysed by both PCR and light microscopy and no cysts were detected, the calculated detection limit was 20 cysts per gram of lettuce; however, by PCR, E. coli was detected in eight of ten randomly selected samples of lettuce. These data highlight the need to validate procedures for routine quality assurance. These PCR-based assays can be employed as alternative methods for the detection of G. intestinalis and E. coli and have the potential to allow for the automation and simultaneous detection of protozoa and bacterial pathogens in multiple samples. Significance and impact of the study: There are few studies for Giardia intestinalis detection in food because methods for its identification are difficult for routine implementation. Here, we developed a PCR-based method as an alternative to the direct observation of cysts in lettuce by light microscopy. Additionally, Escherichia coli was detected by PCR and the sanitary quality of lettuce was evaluated using molecular and standard microbiological methods. Using PCR, the detection probability of Giardia cysts inoculated onto samples of lettuce was improved compared to light microscopy, with the advantage of easy automation. These methods may be employed to perform timely and affordable detection of foodborne pathogens. © 2015 The Society for Applied Microbiology.

  14. Photoprotection vs. Photoinhibition of Photosystem II in Transplastomic Lettuce (Lactuca sativa) Dominantly Accumulating Astaxanthin.

    Science.gov (United States)

    Fujii, Ritsuko; Yamano, Nami; Hashimoto, Hideki; Misawa, Norihiko; Ifuku, Kentaro

    2016-07-01

    Transplastomic (chloroplast genome-modified; CGM) lettuce that dominantly accumulates astaxanthin grows similarly to a non-transgenic control with almost no accumulation of naturally occurring photosynthetic carotenoids. In this study, we evaluated the activity and assembly of PSII in CGM lettuce. The maximum quantum yield of PSII in CGM lettuce was <0.6; however, the quantum yield of PSII was comparable with that in control leaves under higher light intensity. CGM lettuce showed a lower ability to induce non-photochemical quenching (NPQ) than the control under various light intensities. The fraction of slowly recovering NPQ in CGM lettuce, which is considered to be photoinhibitory quenching (qI), was less than half that of the control. In fact, 1 O 2 generation was lower in CGM than in control leaves under high light intensity. CGM lettuce contained less PSII, accumulated mostly as a monomer in thylakoid membranes. The PSII monomers purified from the CGM thylakoids bound echinenone and canthaxanthin in addition to β-carotene, suggesting that a shortage of β-carotene and/or the binding of carbonyl carotenoids would interfere with the photophysical function as well as normal assembly of PSII. In contrast, high accumulation of astaxanthin and other carbonyl carotenoids was found within the thylakoid membranes. This finding would be associated with the suppression of photo-oxidative stress in the thylakoid membranes. Our observation suggests the importance of a specific balance between photoprotection and photoinhibition that can support normal photosynthesis in CGM lettuce producing astaxanthin. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  15. Feeding behaviour and performance of different populations of the black currant-lettuce aphid, Nasonovia ribisnigri, on resistant and susceptible lettuce

    NARCIS (Netherlands)

    Broeke, ten C.J.M.; Dicke, M.; Loon, van J.J.A.

    2013-01-01

    When crops are bred for resistance to herbivores, these herbivores are under strong selection pressure to overcome this resistance, which may result in the emergence of virulent biotypes. This is a growing problem for crop species attacked by aphids. The Nr-gene in lettuce confers near-complete

  16. Incidence of Lettuce mosaic virus in lettuce and its detection by polyclonal antibodies produced against recombinant coat protein expressed in Escherichia coli.

    Science.gov (United States)

    Sharma, Prachi; Sharma, Susheel; Singh, Jasvir; Saha, Swati; Baranwal, V K

    2016-04-01

    Lettuce mosaic virus (LMV), a member of the genus Potyvirus of family Potyviridae, causes mosaic disease in lettuce has recently been identified in India. The virus is seed borne and secondary infection occurs through aphids. To ensure virus freedom in seeds it is important to develop diagnostic tools, for serological methods the production of polyclonal antibodies is a prerequisite. The coat protein (CP) gene of LMV was amplified, cloned and expressed using pET-28a vector in Escherichia coli BL21DE3 competent cells. The LMV CP was expressed as a fusion protein containing a fragment of the E. coli His tag. The LMV CP/His protein reacted positively with a commercial antiserum against LMV in an immunoblot assay. Polyclonal antibodies purified from serum of rabbits immunized with the fusion protein gave positive results when LMV infected lettuce (Lactuca sativa) was tested at 1:1000 dilution in PTA-ELISA. These were used for specific detection of LMV in screening lettuce accessions. The efficacy of the raised polyclonal antiserum was high and it can be utilized in quarantine and clean seed production. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Preliminary investigations of the rhizosphere nature of hydroponically grown lettuces

    Science.gov (United States)

    Antunes, Inês; Paille, Christel; Lasseur, Christophe

    Due to capabilities of current launchers, future manned exploration beyond the Earth orbit will imply long journeys and extended stays on planet surfaces. For this reason, it is of a great importance to develop a Regenerative Life Support System that enables the crew to be, to a very large extent, metabolic consumables self-sufficient. In this context, the European Space Agency, associated with a scientific and engineering con-sortium, initiated in 1989 the Micro-Ecological Life Support System Alternative (MELiSSA) project. This concept, inspired on a terrestrial ecosystem (i.e. a lake), comprises five intercon-nected compartments inhabited by micro-organisms and higher-plants aiming to produce food, fresh water, and oxygen from organic waste, carbon dioxide, and minerals. Given the important role of the higher-plant compartment for the consumption of carbon dioxide and the production of oxygen, potable water, and food, it was decided to study the microbial communities present in the root zone of the plants (i.e. the rhizosphere), and their synergistic and antagonistic influences in the plant growth. This understanding is important for later investigations concerning the technology involved in the higher plant compartment, since the final goal is to integrate this compartment inside the MELiSSA loop and to guarantee a healthy and controlled environment for the plants to grow under reduced-gravity conditions. To perform a preliminary assessment of the microbial populations of the root zone, lettuces were grown in a hydroponic system and their growth was characterized in terms of nutrient uptake, plant diameter, and plant wet and dry weights. In parallel, the microbial population, bacteria and fungi, present in the hydroponic medium and also inside and outside the roots were analyzed in terms of quantity and nature. The goal of this presentation is to give a preliminary review in the plant root zone of the micro-organisms communities and as well their proportions

  18. Preference and life history traits of Aphelinus abdominalis (Hymenoptera: Aphelinidae) when offered different development stages of the lettuce aphid Nasonovia ribisnigri (Hemiptera: Aphididae)

    DEFF Research Database (Denmark)

    Shrestha, Govinda; Skovgård, Henrik; Steenberg, Tove

    2015-01-01

    stages of the lettuce aphid were exposed for parasitism compared with older developmental stages. This pattern was supported in the choice experiment where significantly more 2nd instar lettuce aphids were parasitised than alatoid 4th instars, with Manly’s preference index (mean ± SE) for the former...... %) were found across all host stages of the lettuce aphid....

  19. Selection for resistance to Verticillium wilt caused by race 2 isolates of Verticillium dahliae in accessions of lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Verticillium wilt of lettuce caused by Verticillium dahliae can cause severe economic damage to lettuce producers. The pathogen exists as two races (races 1 and 2) in lettuce, and complete resistance to race 1 is known. Resistance to race 2 isolates has not been reported, and production of race 1 re...

  20. Performance and feeding behaviour of two biotypes of the black currant-lettuce aphid, Nasonovia ribisnigri, on resistant and susceptible Lactuca sativa near-isogenic lines

    NARCIS (Netherlands)

    Broeke, ten C.J.M.; Dicke, M.; Loon, van J.J.A.

    2013-01-01

    The black currant-lettuce aphid, Nasonovia ribisnigri, is an important pest of cultivated lettuce, Lactuca sativa. Since 1982, the control of this aphid on lettuce is largely based on host plant resistance, conferred by the Nr gene, introgressed from Lactuca virosa. The resistance mechanism remains

  1. Escherichia coli Contamination of Lettuce Grown in Soils Amended with Animal Slurry

    DEFF Research Database (Denmark)

    Jensen, Annette Nygaard; Storm, Christina; Forslund, Anita

    2013-01-01

    A pilot study was conducted to assess the transfer of Escherichia coli from animal slurry fertilizer to lettuce, with E. coli serving as an indicator of fecal contamination and as an indicator for potential bacterial enteric pathogens. Animal slurry was applied as fertilizer to three Danish agric...... types between slurry, soil, and lettuce. The frequent finding of fecal-contaminated lettuce indicates that human pathogens such as Salmonella and Campylobacter can be present and represent food safety hazards.......A pilot study was conducted to assess the transfer of Escherichia coli from animal slurry fertilizer to lettuce, with E. coli serving as an indicator of fecal contamination and as an indicator for potential bacterial enteric pathogens. Animal slurry was applied as fertilizer to three Danish....... coli. A relatively higher frequency of E. coli in lettuce compared with the soil samples at harvest suggests environmental sources of fecal contamination, e.g., wildlife. The higher frequency was supported by the finding of 21 different PFGE types among the E. coli isolates, with only a few common PFGE...

  2. Respiration rate and ethylene production of fresh cut lettuce as affected by cutting grade

    Directory of Open Access Journals (Sweden)

    J. MARTÍNEZ

    2008-12-01

    Full Text Available For designing optimal polymeric films for modified atmosphere packaging of whole heads as well as for minimally fresh processed (fresh-cut Iceberg lettuce ‘Coolguard’, the effect of several cutting grades on respiration rate (RR and ethylene production at 5ºC was studied. According to common industrial practices cutting grades less than 0.5 cm, between 0.5 and 1 cm, and 2 cm length were selected. Results from four experiments were compared to those obtained for whole heads in which a homogenous range of 6 to 8 ml CO2 kg-1 h-1 in RR was found. Compared to whole heads, in fresh-cut lettuce the RR was 2-fold higher. The lowest cutting grade showed the highest respiration rate, and no significant differences in RR among lettuce pieces of intermediate and the highest grades were found. No ethylene production was detected in whole heads, while in minimally processed lettuce pieces only traces were found. For avoiding risks of anaerobic respiration and excessive CO2 levels within packages containing fresh-cut lettuce pieces lower than 0.5 cm length, films with relatively high O2 permeability like standard polypropylene or low-density polyethylene must be selected.;

  3. Occurrence of perchlorate in groundwater, paired farmland soil, lettuce, and rhizosphere soil from Chengdu, China.

    Science.gov (United States)

    Tang, Yulu; Zhong, Bifeng; Qu, Bing; Feng, Shujin; Ding, Sanglan; Su, Shijun; Li, Zhi; Gan, Zhiwei

    2017-05-24

    A total of 28 groundwater, paired farmland soil, lettuce, and its rhizosphere soil samples were collected from Chengdu, China to detect perchlorate levels and to evaluate the relationships of perchlorate concentrations among these matrices. The perchlorate concentrations in the groundwater, farmland soil, lettuce, and rhizosphere soil samples ranged from below detection limit to 60.2 μg L -1 , from below detection limit to 249 μg kg -1 dry weight (dw), from 2.07 to 1010 μg kg -1 wet weight, and from below detection limit to 314 μg kg -1 dw, respectively. Significant correlation was found in the perchlorate levels among the farmland soil, lettuce, and rhizosphere soil, suggesting that they have common pollution sources, or perchlorate might transfer from farmland soil-rhizosphere soil-plant. However, there is no significant correlation between groundwater and the other three matrices, indicating that infiltration from perchlorate contaminated farmland soil was not the predominant source for groundwater pollution in Chengdu. The perchlorate concentrations in the farmland soil and lettuce samples were significantly higher than those in the rhizosphere soil, primarily due to uptake of perchlorate through the rhizosphere micro-environment by lettuce, or accelerated degradation by rhizospheric microorganisms, which contributed more needs further investigation.

  4. Combination of minimal processing and irradiation to improve the microbiological safety of lettuce (Lactuca sativa, L.)

    International Nuclear Information System (INIS)

    Goularte, L.; Martins, C.G.; Morales-Aizpurua, I.C.; Destro, M.T.; Franco, B.D.G.M.; Vizeu, D.M.; Hutzler, B.W.; Landgraf, M.

    2004-01-01

    The feasibility of gamma radiation in combination with minimal processing (MP) to reduce the number of Salmonella spp. and Escherichia coli O157:H7 in iceberg lettuce (Lactuca sativa, L.) (shredded) was studied in order to increase the safety of the product. The reduction of the microbial population during the processing, the D 10 -values for Salmonella spp. and E. coli O157:H7 inoculated on shredded iceberg lettuce as well as the sensory evaluation of the irradiated product were evaluated. The immersion in chlorine (200 ppm) reduced coliform and aerobic mesophilic microorganisms by 0.9 and 2.7 log, respectively. D-values varied from 0.16 to 0.23 kGy for Salmonella spp. and from 0.11 to 0.12 kGy for E. coli O157:H7. Minimally processed iceberg lettuce exposed to 0.9 kGy does not show any change in sensory attributes. However, the texture of the vegetable was affected during the exposition to 1.1 kGy. The exposition of MP iceberg lettuce to 0.7 kGy reduced the population of Salmonella spp. by 4.0 log and E. coli by 6.8 log without impairing the sensory attributes. The combination of minimal process and gamma radiation to improve the safety of iceberg lettuce is feasible if good hygiene practices begins at farm stage

  5. Survival of Escherichia coli on Lettuce under Field Conditions Encountered in the Northeastern United States.

    Science.gov (United States)

    Weller, Daniel L; Kovac, Jasna; Roof, Sherry; Kent, David J; Tokman, Jeffrey I; Kowalcyk, Barbara; Oryang, David; Ivanek, Renata; Aceituno, Anna; Sroka, Christopher; Wiedmann, Martin

    2017-07-01

    Although wildlife intrusion and untreated manure have been associated with microbial contamination of produce, relatively few studies have examined the survival of Escherichia coli on produce under field conditions following contamination (e.g., via splash from wildlife feces). This experimental study was performed to estimate the die-off rate of E. coli on preharvest lettuce following contamination with a fecal slurry. During August 2015, field-grown lettuce was inoculated via pipette with a fecal slurry that was spiked with a three-strain cocktail of rifampin-resistant nonpathogenic E. coli. Ten lettuce heads were harvested at each of 13 time points following inoculation (0, 2.5, 5, and 24 h after inoculation and every 24 h thereafter until day 10). The most probable number (MPN) of E. coli on each lettuce head was determined, and die-off rates were estimated. The relationship between sample time and the log MPN of E. coli per head was modeled using a segmented linear model. This model had a breakpoint at 106 h (95% confidence interval = 69, 142 h) after inoculation, with a daily decrease of 0.70 and 0.19 log MPN for 0 to 106 h and 106 to 240 h following inoculation, respectively. These findings are consistent with die-off rates obtained in similar studies that assessed E. coli survival on produce following irrigation. Overall, these findings provide die-off rates for E. coli on lettuce that can be used in future quantitative risk assessments.

  6. Perception of bitterness, sweetness and liking of different genotypes of lettuce.

    Science.gov (United States)

    Chadwick, M; Gawthrop, F; Michelmore, R W; Wagstaff, C; Methven, L

    2016-04-15

    Lettuce is an important leafy vegetable, consumed across the world, containing bitter sesquiterpenoid lactone (SL) compounds that may negatively affect consumer acceptance and consumption. We assessed liking of samples with differing absolute abundance and different ratios of bitter:sweet compounds by analysing recombinant inbred lines (RILs) from an interspecific lettuce mapping population derived from a cross between a wild (L. serriola acc. UC96US23) and domesticated lettuce (L. sativa, cv. Salinas). We found that the ratio of bitter:sweet compounds was a key determinant of bitterness perception and liking. We were able to demonstrate that SLs, such as 8-deoxylactucin-15-sulphate, contribute most strongly to bitterness perception, whilst 15-p-hydroxylphenylacetyllactucin-8-sulphate does not contribute to bitter taste. Glucose was the sugar most highly correlated with sweetness perception. There is a genetic basis to the biochemical composition of lettuce. This information will be useful in lettuce breeding programmes in order to produce leaves with more favourable taste profiles. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Comparison of Land, Water, and Energy Requirements of Lettuce Grown Using Hydroponic vs. Conventional Agricultural Methods.

    Science.gov (United States)

    Barbosa, Guilherme Lages; Gadelha, Francisca Daiane Almeida; Kublik, Natalya; Proctor, Alan; Reichelm, Lucas; Weissinger, Emily; Wohlleb, Gregory M; Halden, Rolf U

    2015-06-16

    The land, water, and energy requirements of hydroponics were compared to those of conventional agriculture by example of lettuce production in Yuma, Arizona, USA. Data were obtained from crop budgets and governmental agricultural statistics, and contrasted with theoretical data for hydroponic lettuce production derived by using engineering equations populated with literature values. Yields of lettuce per greenhouse unit (815 m2) of 41 ± 6.1 kg/m2/y had water and energy demands of 20 ± 3.8 L/kg/y and 90,000 ± 11,000 kJ/kg/y (±standard deviation), respectively. In comparison, conventional production yielded 3.9 ± 0.21 kg/m2/y of produce, with water and energy demands of 250 ± 25 L/kg/y and 1100 ± 75 kJ/kg/y, respectively. Hydroponics offered 11 ± 1.7 times higher yields but required 82 ± 11 times more energy compared to conventionally produced lettuce. To the authors' knowledge, this is the first quantitative comparison of conventional and hydroponic produce production by example of lettuce grown in the southwestern United States. It identified energy availability as a major factor in assessing the sustainability of hydroponics, and it points to water-scarce settings offering an abundance of renewable energy (e.g., from solar, geothermal, or wind power) as particularly attractive regions for hydroponic agriculture.

  8. Bacterial networks and co-occurrence relationships in the lettuce root microbiota.

    Science.gov (United States)

    Cardinale, Massimiliano; Grube, Martin; Erlacher, Armin; Quehenberger, Julian; Berg, Gabriele

    2015-01-01

    Lettuce is one of the most common raw foods worldwide, but occasionally also involved in pathogen outbreaks. To understand the correlative structure of the bacterial community as a network, we studied root microbiota of eight ancient and modern Lactuca sativa cultivars and the wild ancestor Lactuca serriola by pyrosequencing of 16S rRNA gene amplicon libraries. The lettuce microbiota was dominated by Proteobacteria and Bacteriodetes, as well as abundant Chloroflexi and Actinobacteria. Cultivar specificity comprised 12.5% of the species. Diversity indices were not different between lettuce cultivar groups but higher than in L. serriola, suggesting that domestication lead to bacterial diversification in lettuce root system. Spearman correlations between operational taxonomic units (OTUs) showed that co-occurrence prevailed over co-exclusion, and complementary fluorescence in situ hybridization-confocal laser scanning microscopy (FISH-CLSM) analyses revealed that this pattern results from both potential interactions and habitat sharing. Predominant taxa, such as Pseudomonas, Flavobacterium and Sphingomonadaceae rather suggested interactions, even though these are not necessarily part of significant modules in the co-occurrence networks. Without any need for complex interactions, single organisms are able to invade into this microbial network and to colonize lettuce plants, a fact that can influence the susceptibility to pathogens. The approach to combine co-occurrence analysis and FISH-CLSM allows reliably reconstructing and interpreting microbial interaction networks. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. Acidovorax valerianellae sp. nov., a novel pathogen of lamb's lettuce [Valerianella locusta (L.) Laterr].

    Science.gov (United States)

    Gardan, Louis; Stead, David E; Dauga, Catherine; Gillis, Moniek

    2003-05-01

    Bacterial spot disease of lamb's lettuce [Valerianella locusta (L.) Laterr.] was first observed in fields in 1991. This new bacterial disease is localized in western France in high-technology field production of lamb's lettuce for the preparation of ready-to-use salad. Nineteen strains isolated in 1992 and 1993 from typical black leaf spots of naturally infected lamb's lettuce were characterized and compared with reference strains of Acidovorax and Delftia. The pathogenicity of the 19 strains was confirmed by artificial inoculation. Biochemical and physiological tests, fatty acid profiles, DNA-DNA hybridization and other nucleic acid-based tests were performed. A numerical taxonomic analysis of the 19 lamb's lettuce strains showed a single homogeneous phenon closely related to previously described phytopathogenic taxa of the genus Acidovorax. DNA-DNA hybridization studies showed that the lamb's lettuce strains were 91-100% related to a representative strain, strain CFBP 4730(T), and constituted a discrete DNA hybridization group, indicating that they belong to the same novel species. Results from DNA-rRNA hybridization, 16S rRNA sequence analysis and fatty acid analysis studies confirmed that this novel species belongs to the beta-subclass of the Proteobacteria and, more specifically, to the family Comamonadaceae and the genus Acidovorax. The name Acidovorax valerianellae sp. nov. is proposed for this novel taxon of phytopathogenic bacteria. The type strain is strain CFBP 4730(T) (= NCPPB 4283(T)).

  10. Endophytic fungi occurring in fennel, lettuce, chicory, and celery--commercial crops in southern Italy.

    Science.gov (United States)

    D'Amico, Margherita; Frisullo, Salvatore; Cirulli, Matteo

    2008-01-01

    The occurrence of endophytic fungi in fennel, lettuce, chicory, and celery crops was investigated in southern Italy. A total of 186 symptomless plants was randomly collected and sampled at the stage of commercial ripeness. Fungal species of Acremonium, Alternaria, Fusarium, and Plectosporium were detected in all four crops; Plectosporium tabacinum was the most common in all crop species and surveyed sites. The effect of eight endophytic isolates (five belonging to Plectosporium tabacinum and three to three species of Acremonium) inoculated on lettuce plants grown in gnotobiosis was assessed by recording plant height, root length and dry weight, collar diameter, root necrosis, and leaf yellowing. P. tabacinum and three species of Acremonium, inoculated on gnotobiotically grown lettuce plants, showed pathogenic activity that varied with the fungal isolate. Lettuce plants inoculated with the isolates Ak of Acremonium kiliense, Ac of Acremonium cucurbitacearum, and P35 of P. tabacinum showed an increased root growth, compared to the non-inoculated control. The high frequency of P. tabacinum isolation recorded in lettuce plants collected in Bari and Metaponto, and in fennel plants from Foggia agricultural districts, suggests a relationship not only between a crop species and P. tabacinum, but also between the occurrence of the endophyte and the crop rotation history of the soil.

  11. Combination of minimal processing and irradiation to improve the microbiological safety of lettuce (Lactuca sativa, L.)

    Energy Technology Data Exchange (ETDEWEB)

    Goularte, L.; Martins, C.G.; Morales-Aizpurua, I.C.; Destro, M.T.; Franco, B.D.G.M.; Vizeu, D.M.; Hutzler, B.W.; Landgraf, M. E-mail: landgraf@usp.br

    2004-10-01

    The feasibility of gamma radiation in combination with minimal processing (MP) to reduce the number of Salmonella spp. and Escherichia coli O157:H7 in iceberg lettuce (Lactuca sativa, L.) (shredded) was studied in order to increase the safety of the product. The reduction of the microbial population during the processing, the D{sub 10}-values for Salmonella spp. and E. coli O157:H7 inoculated on shredded iceberg lettuce as well as the sensory evaluation of the irradiated product were evaluated. The immersion in chlorine (200 ppm) reduced coliform and aerobic mesophilic microorganisms by 0.9 and 2.7 log, respectively. D-values varied from 0.16 to 0.23 kGy for Salmonella spp. and from 0.11 to 0.12 kGy for E. coli O157:H7. Minimally processed iceberg lettuce exposed to 0.9 kGy does not show any change in sensory attributes. However, the texture of the vegetable was affected during the exposition to 1.1 kGy. The exposition of MP iceberg lettuce to 0.7 kGy reduced the population of Salmonella spp. by 4.0 log and E. coli by 6.8 log without impairing the sensory attributes. The combination of minimal process and gamma radiation to improve the safety of iceberg lettuce is feasible if good hygiene practices begins at farm stage.

  12. Evaluation of respiratory parameters in minimally processed lettuce grown under organic or conventional system

    Directory of Open Access Journals (Sweden)

    Júlio César Mello

    2010-12-01

    Full Text Available The increased preference for minimally processed vegetables has been attributed to the health benefits associated with fresh produce and the demand for ready-to-eat salads. In this paper, lettuce (Lactuca sativa L. was evaluated for the effects of different cropping systems on the respiratory properties. Lettuce was packaged in low density polyethylene bags and stored in a refrigerator at 4 ºC. The concentration of carbon dioxide and oxygen inside the package was monitored during the storage at zero, three, six, eight, ten and twelve days by gas chromatography. Dry matter variation was measured gravimetrically up to day fourteen of storage. Values of respiratory rate for conventional lettuce increased from day 1 to 3 and remained low, while respiratory rate of the organic lettuce increased three-fold up to day 8, stabilizing at a high level. Variation in dry matter during storage also resulted from differences between the two cultivation systems. The highest content of dry matter was achieved by organic lettuce.

  13. The Protective Role of Lettuce oil (Lactuca sativa) against Radiation induced Biological Hazards in Male Rats

    International Nuclear Information System (INIS)

    Abdel-Magied, N.; Ahmed, A.G.

    2011-01-01

    This study was conducted to clarify the potential role of lettuce oil against damages induced in rats due to exposure to gamma radiation. Adult male albino rats (120-150 g) were divided into 4 groups each of 12 animals. The first group was considered control animals. The second group received, via gavages, lettuce oil (200 mg/Kg body weight) for 3 weeks. The third group was subjected to a single dose of 6.5Gy whole body gamma irradiation. The fourth group received lettuce oil for 3 weeks then was exposed to radiation. Blood samples were collected 1 and 7 days post irradiation. Exposure of rats to gamma irradiation caused a significant increase in the level of glucose, total cholesterol (TC), triglycerides (TG), malondialdehyde (MDA) and follicle stimulating hormone (FSH) while a significant decrease was recorded in glutathione content (GSH), superoxide dismutase (SOD) and catalase activities, white blood cells (WBCs), red blood cells (RBCs), haemoglobin content (Hb), haematocrit percentage (Hct%), mean corpuscular volume (MCV), platelets (PLT), leutinizing hormone (LH) and testosterone hormone . In rats treated with lettuce oil then exposed to radiation, the results showed an improvement in all previous parameters. It could be concluded that lettuce oil might reduce the biological hazards in rats induced by gamma irradiation

  14. Combination of minimal processing and irradiation to improve the microbiological safety of lettuce ( Lactuca sativa, L.)

    Science.gov (United States)

    Goularte, L.; Martins, C. G.; Morales-Aizpurúa, I. C.; Destro, M. T.; Franco, B. D. G. M.; Vizeu, D. M.; Hutzler, B. W.; Landgraf, M.

    2004-09-01

    The feasibility of gamma radiation in combination with minimal processing (MP) to reduce the number of Salmonella spp. and Escherichia coli O157:H7 in iceberg lettuce ( Lactuca sativa, L.) (shredded) was studied in order to increase the safety of the product. The reduction of the microbial population during the processing, the D10-values for Salmonella spp. and E. coli O157:H7 inoculated on shredded iceberg lettuce as well as the sensory evaluation of the irradiated product were evaluated. The immersion in chlorine (200 ppm) reduced coliform and aerobic mesophilic microorganisms by 0.9 and 2.7 log, respectively. D-values varied from 0.16 to 0.23 kGy for Salmonella spp. and from 0.11 to 0.12 kGy for E. coli O157:H7. Minimally processed iceberg lettuce exposed to 0.9 kGy does not show any change in sensory attributes. However, the texture of the vegetable was affected during the exposition to 1.1 kGy. The exposition of MP iceberg lettuce to 0.7 kGy reduced the population of Salmonella spp. by 4.0 log and E. coli by 6.8 log without impairing the sensory attributes. The combination of minimal process and gamma radiation to improve the safety of iceberg lettuce is feasible if good hygiene practices begins at farm stage.

  15. Fertilization effect on yield and nitrate content in organically produced lettuce

    Directory of Open Access Journals (Sweden)

    Čabilovski Ranko

    2010-01-01

    Full Text Available The effect of applying different organic materials (OM on yield and nitrate content in lettuce was studied in a field experiment on a farm registered for organic production during two years (2007 and 2008. Treatments were: farmyard manure (ST, guano (G, milled soybean (Glicine hispida seed (S; milled forage pea (Pisum sativum seed (P and control treatment (q. Biannual average fresh matter (FM yield of lettuce on fertilized plots ranges from 45.44 t ha-1 (P to 46,38 t ha-1 (ST and was significantly higher than fresh matter yield of the control (39.34 t ha-1, while the differences between fertilized treatments were not significant. Nitrate content in the fresh mass of lettuce in all treatments in both years was below the maximum allowed content (2.500 mg kg-1 regulated by the EU (Commission Regulation (EC, No 466/2001. In both years, the lowest nitrate content in the fresh mass of lettuce was recorded with the control treatment (q and highest with S treatment. Nitrate contents with G, P and S treatments were significantly higher than that recorded with FYM and q, whereas the differences between FYM and q were not significant in either the first or the second year of research. Linear correlation (r = 0.83**in 2007; r = 0.91** in 2008 was found between the content of mineral N in the soil and nitrate content in the FM of lettuce at the moment of harvesting in both years. .

  16. Cadmium and chromium effects on seed germination and root elongation in lettuce, spinach and Swiss chard

    Directory of Open Access Journals (Sweden)

    Oscar V Bautista

    2013-04-01

    Full Text Available The La Ramada district and the Bogota River are the principal water resources used for horticultural crop production on the Bogota Plateau, which contain channel pollutant materials, including heavy metals due to domestic and industrial activities on the Plateau. These materials have effects on crop production in this zone. The present research, under laboratory conditions, aimed to evaluate the effect of three concentrations (25, 35 and 50 µM L-1 of cadmium (Cd and chromium (Cr on imbibition, seed germination and root elongation in lettuce (Lactuca sativa var. Batavia, Swiss chard (Beta vulgaris var. cicla "White Ribbed", and spinach (Spinacia oleracea Hib. 424, three species widely cultivated on the Plateau. The three species used for evaluation showed a differential susceptibility response to Cd and Cr. In lettuce, fresh weight increase (imbibition was lower with all Cd concentrations at the last day of observation and at 25 µM L-1 of Cd in Swiss chard. Cadmium reduced seed germination by up to 46%, 97% and 8% in Swiss chard, lettuce and spinach, respectively. Also, root elongation decreased in Cd treatments by up to 57%, 89% and 56%, for Swiss chard, lettuce and spinach, respectively. Chromium, which showed fewer negative effects, decreased germination by up to 29% in Swiss chard, 6% in lettuce and 34% in spinach, as compared to the control

  17. Efficient and stable transformation of Lactuca sativa L. cv. Cisco (lettuce) plastids.

    Science.gov (United States)

    Kanamoto, Hirosuke; Yamashita, Atsushi; Asao, Hiroshi; Okumura, Satoru; Takase, Hisabumi; Hattori, Masahira; Yokota, Akiho; Tomizawa, Ken-Ichi

    2006-04-01

    Transgenic plastids offer unique advantages in plant biotechnology, including high-level foreign protein expression. However, broad application of plastid genome engineering in biotechnology has been largely hampered by the lack of plastid transformation systems for major crops. Here we describe the development of a plastid transformation system for lettuce, Lactuca sativa L. cv. Cisco. The transforming DNA carries a spectinomycin-resistance gene (aadA) under the control of lettuce chloroplast regulatory expression elements, flanked by two adjacent lettuce plastid genome sequences allowing its targeted insertion between the rbcL and accD genes. On average, we obtained 1 transplastomic lettuce plant per bombardment. We show that lettuce leaf chloroplasts can express transgene-encoded GFP to approximately 36% of the total soluble protein. All transplastomic T0 plants were fertile and the T1 progeny uniformly showed stability of the transgene in the chloroplast genome. This system will open up new possibilities for the efficient production of edible vaccines, pharmaceuticals, and antibodies in plants.

  18. Distribution and population development of Nasonovia ribisnigri (Homoptera: Aphididae) in iceberg lettuce.

    Science.gov (United States)

    Liu, Yong-Biao

    2004-06-01

    A field study was conducted to determine the distribution and development of aphid Nasonovia ribisnigri (Mosley) (Homoptera: Aphididae) populations in iceberg lettuce, Lactuca sativa L. 'Salinas'. Lettuce plants were transplanted and caged individually in the field and inoculated with apterous N. ribisnigri at 0, 1, 2, 3, and 4 wk after transplanting in spring and fall 2002. Plants were harvested 15-50 d after inoculations; numbers of alates and apterous N. ribisnigri were counted or estimated on each leaf for each plant. Inoculations during all 5 wk of plant development resulted in successful colonization of lettuce heads. Results indicated that head formation did not reduce the risk of colonization by N. ribisnigri to iceberg lettuce; plants were susceptible to colonization by N. ribisnigri throughout their development. For later inoculations, N. ribisnigri populations were relatively smaller, and aphids were found mostly within the heads. For earlier inoculations, N. ribisnigri populations were larger, and within-plant distributions shifted toward frame leaves. The shift of population distributions toward frame leaves correlated significantly with increases in N. ribisnigri population density. For most inoculations, more aphids were present on wrapper leaves than on other leaves. The proportion of alates did not vary significantly with population density. Population development of N ribisnigri also correlated significantly with heat unit accumulation. Yellow sticky cards were used to monitor alates in each cage. Catches of N. ribisnigri alates on yellow sticky cards were significantly correlated with total numbers of alates as well as with total population sizes on individual lettuce plants.

  19. Assessment of Escherichia coli O157:H7 transference from soil to Iceberg Lettuce via a contaminated harvesting knife

    Science.gov (United States)

    The potential for coring knives to cross-contaminate lettuce heads with pathogens was evaluated for both ring and blade ends. Rings and blades artificially contaminated with Escherichia coli O157:H7 (EHEC), were used to core three successive heads of iceberg lettuce. The coring rings and blades were...

  20. Baby leaf lettuce germplasm enhancement: developing diverse populations with resistance to bacterial leaf spot caused by Xanthomonas campestris pv. vitians

    Science.gov (United States)

    Baby leaf lettuce cultivars with resistance to bacterial leaf spot (BLS) caused by Xanthomonas campestris pv. vitians (Xcv) are needed to reduce crop losses. The objectives of this research were to assess the genetic diversity for BLS resistance in baby leaf lettuce cultivars and to select early gen...

  1. Assessing genetic variation in lettuce for traits related to nitrogen use efficiency using susceptibility and relative efficiency indices

    Science.gov (United States)

    Lettuce is a high value commodity in the USA with annual value of ~$2.5 billion. California produces ~75 percent of all lettuce in the country. Overuse of agricultural inputs for crop production can cause detrimental effects to the health of Californians as well as on agricultural and natural resour...

  2. Discrimination methods of biological contamination on fresh-cut lettuce based on VNIR and NIR hyperspectral imaging

    Science.gov (United States)

    Multispectral imaging algorithms were developed using visible-near-infrared (VNIR) and near-infrared (NIR) hyperspectral imaging (HSI) techniques to detect worms on fresh-cut lettuce. The optimal wavebands that detect worm on fresh-cut lettuce for each type of HSI were investigated using the one-way...

  3. Effector-mediated discovery of a novel resistance gene against Bremia Lactucae in a nonhost lettuce species

    NARCIS (Netherlands)

    Giesbers, A.K.J.; Pelgrom, Alexandra; Visser, R.G.F.; Niks, R.E.; Ackerveken, Van Den Guido; Jeuken, M.J.W.

    2017-01-01

    Candidate effectors from lettuce downy mildew (Bremia lactucae) enable high-throughput germplasm screening for the presence of resistance (R) genes. The nonhost species Lactuca saligna comprises a source of B. lactucae R genes that has hardly been exploited in lettuce breeding. Its

  4. Effector-mediated discovery of a novel resistance gene against Bremia lactucae in a nonhost lettuce species

    NARCIS (Netherlands)

    Giesbers, Anne K J; Pelgrom, Alexandra J E; Visser, Richard G F; Niks, Rients E; Van den Ackerveken, Guido; Jeuken, Marieke J W

    2017-01-01

    Candidate effectors from lettuce downy mildew (Bremia lactucae) enable high-throughput germplasm screening for the presence of resistance (R) genes. The nonhost species Lactuca saligna comprises a source of B. lactucae R genes that has hardly been exploited in lettuce breeding. Its

  5. Effects of pre-and postharvest lighting on quality and shelf life of fresh-cut lettuce

    NARCIS (Netherlands)

    Woltering, E.J.; Witkowska, I.M.

    2016-01-01

    The effects of pre-and postharvest lighting on quality and shelf life of fresh-cut lettuce was investigated. Lettuce was grown under different light intensities (120 and 250 μmol m-2 s-1 PAR from fluorescent tubes) and quality at harvest and subsequent postharvest

  6. Application of chlorophyll fluorescence imaging and hyperspectral imaging in evaluation of decay in fresh-cut lettuce

    Science.gov (United States)

    Lettuce (Lactuca sativa L.) is commercially the most popular leafy vegetable whose leaves are usually consumed raw. Cleaned, cored, and chopped (fresh-cut) lettuce is a desirable, but highly perishable product. Modified atmosphere packaging (MAP) has been introduced to maintain quality of fresh-cut ...

  7. Improved Design and Ultrasound-assisted Sanitation of Lettuce Harvesting Knives for Minimizing Escherichia coli O157:H7 Contamination

    Science.gov (United States)

    Laboratory studies have shown that Escherichia coli O157:H7 can be transferred to lettuce during harvesting. Knives used for lettuce coring-in-field (CIF) harvesting are likely to contact soil and consequently could serve as a vehicle for the transmission of food-borne human pathogens from contamin...

  8. A note on the measurement of genetic diversity within genebank accessions of lettuce (Lactuca sativa L.) using AFLP markers

    NARCIS (Netherlands)

    Jansen, J.; Verbakel, H.; Peleman, J.; Hintum, van T.J.L.

    2006-01-01

    This paper discusses a statistical approach for measuring genetic diversity within genebank accessions of a self-fertilising species. This approach is applied to lettuce (Lactuca sativa L.), using AFLP marker data on a set of 1,390 accessions, representing six different lettuce types. Knowledge of

  9. Health effect of vegetable-based diet: lettuce consumption improves cholesterol metabolism and antioxidant status in the rat.

    Science.gov (United States)

    Nicolle, Catherine; Cardinault, Nicolas; Gueux, Elyett; Jaffrelo, Lydia; Rock, Edmond; Mazur, Andrzej; Amouroux, Pierre; Rémésy, Christian

    2004-08-01

    It is often assumed that fruits and vegetables contribute to protect against degenerative pathologies such as cardiovascular diseases. Besides epidemiological observations, scientific evidences for their mechanism of action are scarce. In the present study, we investigated the mean term and post-prandial effects of lettuce ingestion on lipid metabolism and antioxidant protection in the rat. Feeding rats a 20% lettuce diet for 3 weeks resulted in a decrease cholesterol LDL/HDL ratio and a marked decrease of liver cholesterol levels (-41%). Concurrently, fecal total steroid excretion increased (+44%) and apparent absorption of dietary cholesterol was significantly depressed (-37%) by the lettuce diet. Lettuce diet also displayed an improvement of vitamin E/TG ratio in plasma and limited lipid peroxidation in heart as evidenced by TBARS. In post-prandial experiment, lettuce intake significantly increased both ascorbic acid and alpha-tocopherol plasma levels which contribute to improve plasma antioxidant capacity within 2 h of consumption. Other lipid-soluble antioxidants (lutein and vitamin E) may also improve the plasma antioxidant capacity. Lettuce consumption increases the total cholesterol end-products excretion and improves antioxidant status due to the richness in antioxidants (vitamins C, E and carotenoids). In our model, lettuce clearly shows a beneficial effect on lipid metabolism and on tissue oxidation. Therefore regular consumption of lettuce should contribute to improve protection against cardiovascular diseases. Copyright 2003 Elsevier Ltd.

  10. Aphid transmission of Lettuce necrotic leaf curl virus, a member of atentative new subgroup within the genus Torradovirus

    NARCIS (Netherlands)

    Verbeek, M.; Dullemans, A.M.; Vlugt, van der R.A.A.

    2017-01-01

    Lettuce necrotic leaf curl virus (LNLCV) was described as the first non-tomato-infecting member of the genus Torradovirus. Until today, the virus was found only in The Netherlands in two different areas in open field crops of lettuce. In 2015, LNLCV was accepted by the ICTV as a new member of the

  11. Feeding behavior and performance of Nasonovia ribisnigri on grafts, detached leaves, and leaf disks of resistant and susceptible lettuce

    NARCIS (Netherlands)

    Broeke, ten Cindy J.M.; Dicke, Marcel; Loon, van Joop J.A.

    2016-01-01

    Aphids are dependent on the phloem sap of plants as their only source of nutrients. Host-plant resistance in lettuce, Lactuca sativa L. (Asteraceae), mediated by the Nr gene is used to control the lettuce aphid Nasonovia ribisnigri (Mosely) (Hemiptera: Aphididae). The resistance is located in the

  12. Over fertilization limits lettuce productivity because of osmotic stress

    Directory of Open Access Journals (Sweden)

    Francisco Albornoz

    2015-09-01

    Full Text Available It is customary that growers apply high doses of nutrients to the soil in order to achieve high yields, with detrimental consequences for the environment; but no information exists with regards to the crop response to high fertilization levels. To evaluate the physiological response of lettuce (Lactuca sativa L. to various root zone nutrient concentrations (expressed as electrical conductivity, from 0.6 to 10 dS m-1, a replicated experiment was conducted using increasing concentrations of macronutrients applied to the root zone in an aeroponic system. Leaf photosynthesis and chlorophyll fluorescence were measured using a portable infrared gas analyzer attached with a fluorometer. Leaf nutrient content was analyzed by mass spectrometry and NO3-N was determined by flow injection analysis. Leaf photosynthetic rates increased when the solution concentration was raised from 0.6 to 4.8 dS m-1, but further increases in solution concentration did not result in any differences. The enhancement in photosynthetic rates was related to higher concentrations of N, P, Mg, and S in leaves. Leaf K content was correlated with stomatal conductance. Maximum growth was achieved with solution concentrations between 1.2 and 4.8 dS m-1 while at 10.0 dS m-1 leaf production was reduced by 30%. It is concluded that at high concentration of nutrients supplied in the root zone, yield reduces because of a combination of decreased stomatal conductance and leaf area.

  13. Effect of reflective surfaces on a greenhouse lettuce crop

    Energy Technology Data Exchange (ETDEWEB)

    Warman, P.R.; Mayhew, W.J.

    1979-01-01

    The Canadian greenhouse industry is an important segment of horticultural production, providing employment for thousands of people. Continuing increases in the costs of conventional fuel supplies, however, has placed the industry in some jeopardy since the cost of heating during the winter months is also escalating. In response to this problem the Brace Research Institute has developed a single roofed greenhouse designed to capture and store the sun's energy, and to increase the amount of downward solar radiation inside the greenhouse through the use of specularly-reflecting back and side walls. The research investigated the effect of a reflective surface on plant growth, development, and nutritional uptake during fall and the early months of winter. The inside walls of the greenhouse were lined with aluminized polyester to act as a reflective surface and flat black roofing felt paper to provide a non-reflecting surface. Grand Rapids Forcing lettuce was planted from seed into a peat-vermiculite bed and total solar radiation was monitored on the horizontal. Over the duration of the experiment, the reflective side of the greenhouse received more than twice as much solar radiation as the non-reflective side leading to significantly larger plant yields on the reflective side. There were no significant differences in the uptake of the plant macronutrients, N, P, K, Ca, and Mg.

  14. Ethylene synthesis in lettuce seeds: its physiological significance.

    Science.gov (United States)

    Burdett, A N

    1972-12-01

    The germination and pregermination ethylene production of Grand Rapids lettuce seeds (Lactuca sativa L.) incubated at 20 C after a red light treatment are inhibited if the seeds are first imbibed at 30 C for 36 hours. In this study, low concentrations of ethylene were found to enhance the germination of seeds pretreated at 30 C more than that of untreated controls. In the presence of high concentrations of ethylene, pretreated seeds and controls germinated at a similar rate. These results are consistent with the view that a prolonged imbibition at 30 C inhibits germination at a lower temperature through its effect on the ethylene production of the seeds. As a further test of the hypothesis, estimates were made of the pregermination ethylene content of untreated seeds and pretreated seeds incubated in the presence of sufficient ethylene to make them germinate as rapidly as untreated seeds. The values obtained were 0.65 and 0.74 nanoliter of ethylene per gram (dry weight) of seeds, respectively.

  15. Nutrient absorption and response of lettuce to phosphorus fertilization

    Directory of Open Access Journals (Sweden)

    Antonio Ismael Inácio Cardoso

    2012-09-01

    Full Text Available The objective of this study was to evaluate the response of lettuce (cultivar Verônica to different levels of phosphorus fertilization. The experiment was conducted from 25/09/2003 (sowing to 03/12/2003 (harvesting at the Fazenda Experimental São Manuel, UNESP/FCA, Botucatu/SP, under protective structures. The experiment was conducted in a randomized block design, with five treatments (0, 200, 400, 600 and 800kg.ha-1 of P2O5, in the form of triple superphosphate and five replications. Plants were grown in 13L plastic pots containing Latossolo Vermelho Distrófico Típico. A quadratic response was observed for the fresh mass of the plant shoots and leaf area, with maximum equivalent levels of 733 and 756kg.ha-1 of P2O5, respectively, as well as for potassium, calcium, magnesium, sulfur, boron, copper, iron, manganese and zinc accumulation. Linear increases were observed with the treatments of P2O5 for dry mass of the shoots, leaf number, plant height and nitrogen and phosphorus accumulation.

  16. Effect of low-cost irrigation methods on microbial contamination of lettuce irrigated with untreated wastewater

    DEFF Research Database (Denmark)

    Keraita, Bernard; Konradsen, Flemming; Drechsel, P.

    2007-01-01

    OBJECTIVE: To assess the effectiveness of simple irrigation methods such as drip irrigation kits, furrow irrigation and use of watering cans in reducing contamination of lettuce irrigated with polluted water in urban farming in Ghana. METHODS: Trials on drip kits, furrow irrigation and watering...... cans were conducted with urban vegetable farmers. Trials were arranged in a completely randomised block design with each plot having all three irrigation methods tested. This was conducted in both dry and wet seasons. Three hundred and ninety-six lettuce, 72 soil, 15 poultry manure and 32 water samples...... were analysed for thermotolerant coliforms and helminth eggs. RESULTS: Lettuce irrigated with drip kits had the lowest levels of contamination, with, on average, 4 log units per 100 g, fewer thermotolerant coliforms than that irrigated with watering cans. However, drip kits often got clogged, required...

  17. Effects of Nitrogen Fertilizers on the Growth and Nitrate Content of Lettuce (Lactuca sativa L.)

    Science.gov (United States)

    Liu, Cheng-Wei; Sung, Yu; Chen, Bo-Ching; Lai, Hung-Yu

    2014-01-01

    Nitrogen is an essential element for plant growth and development; however, due to environmental pollution, high nitrate concentrations accumulate in the edible parts of these leafy vegetables, particularly if excessive nitrogen fertilizer has been applied. Consuming these crops can harm human health; thus, developing a suitable strategy for the agricultural application of nitrogen fertilizer is important. Organic, inorganic, and liquid fertilizers were utilized in this study to investigate their effect on nitrate concentrations and lettuce growth. The results of this pot experiment show that the total nitrogen concentration in soil and the nitrate concentration in lettuce increased as the amount of nitrogen fertilizer increased. If the recommended amount of inorganic fertilizer (200 kg·N·ha−1) is used as a standard of comparison, lettuce augmented with organic fertilizers (200 kg·N·ha−1) have significantly longer and wider leaves, higher shoot, and lower concentrations of nitrate. PMID:24758896

  18. Fluorescence hyperspectral imaging technique for foreign substance detection on fresh-cut lettuce.

    Science.gov (United States)

    Mo, Changyeun; Kim, Giyoung; Kim, Moon S; Lim, Jongguk; Cho, Hyunjeong; Barnaby, Jinyoung Yang; Cho, Byoung-Kwan

    2017-09-01

    Non-destructive methods based on fluorescence hyperspectral imaging (HSI) techniques were developed to detect worms on fresh-cut lettuce. The optimal wavebands for detecting the worms were investigated using the one-way ANOVA and correlation analyses. The worm detection imaging algorithms, RSI-I (492-626)/492 , provided a prediction accuracy of 99.0%. The fluorescence HSI techniques indicated that the spectral images with a pixel size of 1 × 1 mm had the best classification accuracy for worms. The overall results demonstrate that fluorescence HSI techniques have the potential to detect worms on fresh-cut lettuce. In the future, we will focus on developing a multi-spectral imaging system to detect foreign substances such as worms, slugs and earthworms on fresh-cut lettuce. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  19. Hydroquinone; A novel bioactive compound from plant-derived smoke can cue seed germination of lettuce

    Science.gov (United States)

    Kamran, Muhammad; Khan, Abdul L.; Ali, Liaqat; Hussain, Javid; Waqas, Muhammad; Al-Harrasi, Ahmed; Imran, Qari M.; Kim, Yoon-Ha; Kang, Sang-Mo; Yun, Byung-Wook; Lee, In-Jung

    2017-05-01

    Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus, Aloe vera, Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from Ginkgo biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10 and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control.

  20. Ecotoxicology evaluation of watery extracts of plants on seeds of radish, lettuce and tomato

    Directory of Open Access Journals (Sweden)

    Edisleidy Águila Jiménez

    2016-02-01

    Full Text Available The effect of watery extracts of Nicotiana acuminata, Piper aduncum L. and Crotalaria juncea was evaluated on the germination and the elongación of the roots of seeds of Raphanus sativus (radish, Lactuca sativa L (lettuce and Lycopersicon esculentum (tomato. The extracts were produced at medium scale in the laboratory of formulation of the Faculty of Química- Pharmacy of the “Universidad Central Marta Abreu de las Villas” . It was demonstrated upon concluding the work that the lettuce was the most sensitive species for this type of study. It was concluded that the extracts could be poured to the means to minor concentrations that 0.01% with a margin of security that they are not going to affect the processes of germination and elongacion of the roots. It was determined that one could use the alone rehearsal using the seeds of lettuce like species of rehearsal.

  1. Hydroquinone; A Novel Bioactive Compound from Plant-Derived Smoke Can Cue Seed Germination of Lettuce

    Science.gov (United States)

    Kamran, Muhammad; Khan, Abdul L.; Ali, Liaqat; Hussain, Javid; Waqas, Muhammad; Al-Harrasi, Ahmed; Imran, Qari M.; Kim, Yoon-Ha; Kang, Sang-Mo; Yun, Byung-Wook; Lee, In-Jung

    2017-01-01

    Plant-derived smoke has been known to play an important role in distribution and growth of vegetation. Using a proficiently designed furnace, we extracted smoke from the leaves of four plant viz. Helianthus annuus,Aloe vera,Ginkgo biloba, and Cymbopogon jwarancusa. Smoke dilutions obtained from these plants were obtained in different concentrations to identify potential lettuce growth promoting smoke solution. Results revealed that smoke obtained from G. biloba significantly enhanced the lettuce seed germination. This solution was then partitioned into ethyl acetate, dichloromethane, n-hexane, chloroform and ether fractions. Ethyl acetate fraction was found to be potent to enhance seed germination. This fraction was subjected to column chromatography and spectroscopic techniques to obtain compound 1. This compound was identified as hydroquinone using 1D and 2D NMR techniques. At low concentrations (5, 10, and 20 ppm), compound 1 enhanced the lettuce seed germination; however, higher concentrations inhibited its growth as compared to control. PMID:28553632

  2. Frequency of Verticillium Species in Commercial Spinach Fields and Transmission of V. dahliae from Spinach to Subsequent Lettuce Crops.

    Science.gov (United States)

    Short, D P G; Gurung, S; Koike, S T; Klosterman, S J; Subbarao, K V

    2015-01-01

    Verticillium wilt caused by V. dahliae is a devastating disease of lettuce in California (CA). The disease is currently restricted to a small geographic area in central coastal CA, even though cropping patterns in other coastal lettuce production regions in the state are similar. Infested spinach seed has been implicated in the introduction of V. dahliae into lettuce fields but direct evidence linking this inoculum to wilt epidemics in lettuce is lacking. In this study, 100 commercial spinach fields in four coastal CA counties were surveyed to evaluate the frequency of Verticillium species recovered from spinach seedlings and the area under spinach production in each county was assessed. Regardless of the county, V. isaacii was the most frequently isolated species from spinach followed by V. dahliae and, less frequently, V. klebahnii. The frequency of recovery of Verticillium species was unrelated to the occurrence of Verticillium wilt on lettuce in the four counties but was related to the area under spinach production in individual counties. The transmission of V. dahliae from infested spinach seeds to lettuce was investigated in microplots. Verticillium wilt developed on lettuce following two or three plantings of Verticillium-infested spinach, in independent experiments. The pathogen recovered from the infected lettuce from microplots was confirmed as V. dahliae by polymerase chain reaction assays. In a greenhouse study, transmission of a green fluorescence protein-tagged mutant strain of V. dahliae from spinach to lettuce roots was demonstrated, after two cycles of incorporation of infected spinach residue into the soil. This study presents conclusive evidence that V. dahliae introduced via spinach seed can cause Verticillium wilt in lettuce.

  3. The phytoavailability of cadmium to lettuce in long-term biosolids-amended soils

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S.L.; Chaney, R.L. [Dept. of Agriculture, Beltsville, MD (United States); Angle, J.S. [Univ. of Maryland, College Park, MD (United States). Dept. of Agronomy; Ryan, J.A. [Environmental Protection Agency, Cincinnati, OH (United States). National Risk Management Research Lab.

    1998-09-01

    A field study was conducted to assess the phytoavailability of Cd in long-term biosolids-amended plots managed at high and low pH. The experiment, established 13 to 15 yr prior to the present cropping, on a Christiana fine sandy loam soil used a variety of biosolids. Two of the biosolids had total Cd concentrations of 13.4 and 210 mg kg{sup {minus}1}. A Cd salt treatment, with Cd added to soil at a rate equivalent to the Cd added by the higher Cd biosolids applied at 100 Mg ha{sup {minus}1}, was also included. The lettuce (Lactuca sativa var. longifolia) cultivar (Paris Island Cos) used in the initial study was also used in the current study. Lettuce Cd was compared between treatments, and in relation to the soil Cd/soil organic C (OC) ratio. There has been no significant increase in plant Cd since the initial cropping. With 16% of the biosolids added OC remaining, lettuce grown on the soil amended with the more contaminated biosolids was not different than that of the initial cropping. Further, significantly less Cd was taken up by lettuce grown on biosolids-amended soil than lettuce grown on soil amended with equivalent rates of Cd salt. The Cd concentration in lettuce grown in the low Cd biosolids treatment was not different from the control. These results indicate that the potential hazards associated with food chain transfer of biosolids-applied Cd are substantially lower than equivalent Cd salt treatments, and that the hazards do not increase over time.

  4. CaMV-35S promoter sequence-specific DNA methylation in lettuce.

    Science.gov (United States)

    Okumura, Azusa; Shimada, Asahi; Yamasaki, Satoshi; Horino, Takuya; Iwata, Yuji; Koizumi, Nozomu; Nishihara, Masahiro; Mishiba, Kei-ichiro

    2016-01-01

    We found 35S promoter sequence-specific DNA methylation in lettuce. Additionally, transgenic lettuce plants having a modified 35S promoter lost methylation, suggesting the modified sequence is subjected to the methylation machinery. We previously reported that cauliflower mosaic virus 35S promoter-specific DNA methylation in transgenic gentian (Gentiana triflora × G. scabra) plants occurs irrespective of the copy number and the genomic location of T-DNA, and causes strong gene silencing. To confirm whether 35S-specific methylation can occur in other plant species, transgenic lettuce (Lactuca sativa L.) plants with a single copy of the 35S promoter-driven sGFP gene were produced and analyzed. Among 10 lines of transgenic plants, 3, 4, and 3 lines showed strong, weak, and no expression of sGFP mRNA, respectively. Bisulfite genomic sequencing of the 35S promoter region showed hypermethylation at CpG and CpWpG (where W is A or T) sites in 9 of 10 lines. Gentian-type de novo methylation pattern, consisting of methylated cytosines at CpHpH (where H is A, C, or T) sites, was also observed in the transgenic lettuce lines, suggesting that lettuce and gentian share similar methylation machinery. Four of five transgenic lettuce lines having a single copy of a modified 35S promoter, which was modified in the proposed core target of de novo methylation in gentian, exhibited 35S hypomethylation, indicating that the modified sequence may be the target of the 35S-specific methylation machinery.

  5. Cadmium uptake in above-ground parts of lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Tang, Xiwang; Pang, Yan; Ji, Puhui; Gao, Pengcheng; Nguyen, Thanh Hung; Tong, Yan'an

    2016-03-01

    Because of its high Cd uptake and translocation, lettuce is often used in Cd contamination studies. However, there is a lack of information on Cd accumulation in the above-ground parts of lettuce during the entire growing season. In this study, a field experiment was carried out in a Cd-contaminated area. Above-ground lettuce parts were sampled, and the Cd content was measured using a flame atomic absorption spectrophotometer (AAS). The results showed that the Cd concentration in the above-ground parts of lettuce increased from 2.70 to 3.62mgkg(-1) during the seedling stage, but decreased from 3.62 to 2.40mgkg(-1) during organogenesis and from 2.40 to 1.64mgkg(-1) during bolting. The mean Cd concentration during the seedling stage was significantly higher than that during organogenesis (a=0.05) and bolting (a=0.01). The Cd accumulation in the above-ground parts of an individual lettuce plant could be described by a sigmoidal curve. Cadmium uptake during organogenesis was highest (80% of the total), whereas that during bolting was only 4.34%. This research further reveals that for Rome lettuce: (1) the highest Cd content of above-ground parts occurred at the end of the seedling phase; (2) the best harvest time with respect to Cd phytoaccumulation is at the end of the organogenesis stage; and (3) the organogenesis stage is the most suitable time to enhance phytoaccumulation efficiency by adjusting the root:shoot ratio. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Influence of hydrogel on germination of lettuce and onion seed at different moisture levels

    Directory of Open Access Journals (Sweden)

    Kateřina Pazderů

    2013-01-01

    Full Text Available The influence of Agrisorb (water solution 1, 3, 5 g/l on lettuce and onion seed germination was tested in different moisture conditions (30 ml and 15 ml of water in germination box. Variants with reduced water level germinated much more slowly (MGT parameter than standard variants, though differences in total germination at the end of the test were insignificant. Treated variants of lettuce seeds showed a statistically significant increase in germination energy (GE on the first day (GE1, both water levels, but a significant decrease on the second day (columns GE2, 15 ml. Higher doses of Agrisorb slowed lettuce seed germination (GE2, 30 ml, dose 5 g significantly, similarly see GE2 (15 ml, doses 1, 3, 5 g. This slowdown was apparent for GE3 (both water amount as well. A similar but insignificant effect was evident for onions. There was an influence of cultivar and seed vigour on sensitivity to water stress. The hydrogel application influenced germination of lettuce and onion seeds. Treated lettuce seeds germinated faster than non-treated control in the beginning of germination process. This effect was not recorded in case of slowly germinated onion seed lots. Although influence of Agrisorb was positive in the beginning, higher doses of hydrogel reduced germination energy of treated seed lots (for example GE2, GE4 of both crops in comparison with non-treated control. Higher doses of hydrogel caused longer MGT of lettuce and onion as well.

  7. Combined toxicity of microcystin-LR and copper on lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Cao, Qing; Steinman, Alan D; Wan, Xiang; Xie, Liqiang

    2018-05-10

    Microcystins and copper commonly co-exist in the natural environment, but their combined toxicity remains unclear, especially in terrestrial plants. The present study investigated the toxicity effects of microcystin-LR (0, 5, 50, 500, 1000 μg L -1 ) and copper (0, 50, 500, 1000, 2000 μg L -1 ), both individually and in mixture, on the germination, growth and oxidative response of lettuce. The bioaccumulation of microcystin-LR and copper was also evaluated. Results showed that the decrease in lettuce germination induced by copper alone was not significantly different from that induced by the mixture, and the combined toxicity assessment showed a simple additive effect. Lettuce growth was not significantly reduced by microcystin-LR alone, whereas it was significantly reduced by copper alone and the mixture when copper concentration was higher than 500 μg L -1 . High concentrations of microcystin-LR (1000 μg L -1 ) and copper (≥50 μg L -1 ),as well as their mixture (≥50 + 500 μg L -1 ), induced oxidative stress in lettuce. A synergistic effect on the growth and antioxidative system of lettuce was observed when exposed to low concentrations of the mixture (≤50 + 500 μg L -1 ), whereas an antagonistic effect was observed at high concentrations (≥1000 + 2000 μg L -1 ). Moreover, the interaction of microcystin-LR and copper can increase their accumulation in lettuce. Our results suggest that the toxicity effects of microcystin-LR and copper are exacerbated when they co-exist in the natural environment at low concentrations, which not only negatively affects plant growth but also poses a potential risk to human health via the food chain. Copyright © 2018. Published by Elsevier Ltd.

  8. Effect of acaricidal components isolated from lettuce (Lactuca sativa) on carmine spider mite (Tetranychus cinnabarinus Boisd.).

    Science.gov (United States)

    Li, M; Zhang, Y; Ding, W; Luo, J; Li, S; Zhang, Q

    2018-06-01

    This study aimed to evaluate the acaricidal activity of lettuce (Lactuca sativa) extracts against carmine spider mites (Tetranychus cinnabarinus Boisd.) and isolate the acaricidal components. Acaricidal activities of lettuce extracts isolated from different parts (the leaf, root and seed) using various solvents (petroleum ether, acetone and methanol) were evaluated with slide-dip bioassay and relatively high median lethal concentration (LC50) values were detected. Acetone extracts of lettuce leaves harvested in July and September were fractionated and isolated with silica gel and thin-layer chromatography. Consequently, acetone extracts of lettuce leaves harvested in July exhibited higher acaricidal activity than those harvested in September, with an LC50 value of 0.268 mg ml-1 at 72 h post-treatment. A total of 27 fractions were obtained from the acetone extract of lettuce leaves harvested in July, and mite mortalities with the 11th and 12th fractions were higher than those with the other 25 fractions (LC50: 0.751 and 1.258 mg ml-1 at 48 h post-treatment, respectively). Subsequently, active acaricidal components of the 11th fraction were identified by infrared, nuclear magnetic resonance and liquid chromatography/mass spectrometry. Five components were isolated from the 11th fraction, with components 11-a and 11-b showing relatively high acaricidal activities (LC50: 0.288 and 0.114 mg ml-1 at 48 h post-treatment, respectively). Component 11-a was identified as β-sitosterol. In conclusion, acetone extracts of lettuce leaves harvested in July might be used as a novel phytogenic acaricide to control mites.

  9. Determination of nitrate in lettuce by ion chromatography after microwave water extraction

    Directory of Open Access Journals (Sweden)

    Humberto Brevilato Novaes

    2009-01-01

    Full Text Available Lettuce is worldwide known as the most important vegetable. In this context, most farmers are searching new techniques for best quality products including hydropony. However, nitrate is of great concern, since it has a negative impact on human metabolism. The main objective of the present work was to evaluate the nitrate content of lettuce produced by conventional and hydroponic systems. The determination was conducted by ion chromatography and a new method of extraction was tested using microwave oven digestion. The results indicated that nitrate level produced in the conventional system was lower than in the hydroponic system.

  10. Decontamination and survival of Enterobacteriaceae on shredded iceberg lettuce during storage.

    Science.gov (United States)

    Osaili, Tareq M; Alaboudi, Akram R; Al-Quran, Heba N; Al-Nabulsi, Anas A

    2018-08-01

    Enterobacteriaceae family can contaminate fresh produce at any stage of production either at pre-harvest or post-harvest stages. The objectives of the current study were to i) identify Enterobacteriaceae species on iceberg lettuce, ii) compare the decontamination efficiency of water, sodium hypochlorite (free chlorine 200 ppm), peroxyacetic acid (PA 80 ppm; Kenocid 2100 ® ) or their combinations and ionizing radiation against Enterobacteriaceae on shredded iceberg lettuce and iii) determine the survival of Enterobacteriaceae post-treatment storage of shredded iceberg lettuce at 4, 10 and 25 °C, for up to 7 days. Klebsiella pneumonia spp. pneumonia, Enterobacter cloacae, Klebsiella oxytoca, Pantoea spp., Leclercia adecarboxylata and Kluyvera ascorbate were identified on iceberg lettuce. No significant difference (P≥ 0.05) among Enterobacteriaceae survival after washing with water or sanitizing with sodium hypochlorite or Kenocid 2100 ® (reduction ≤ 0.6 log CFU/g) were found. Combined sanitizer treatments were more effective against Enterobacteriaceae than single washing/sanitizing treatments. Sanitization of iceberg lettuce with combined washing/sanitizing treatments reduced Enterobacteriaceae by 0.85-2.24 CFU/g. Post-treatment growth of Enterobacteriaceae during storage on samples sanitized with sodium hypochlorite and Kenocid 2100 ® was more than on samples washed with water. The D 10 -value of Enterobacteriaceae on shredded iceberg lettuce was 0.21 KGy. The reduction of Enterobacteriaceae populations on iceberg after gamma radiation (0.6 KGy) was 3 log CFU/g, however, Enterobacteriaceae counts increased post-irradiation storage by 4-5 log CFU/g. Therefore, washing shredded iceberg lettuce with combined sanitizing treatment (sodium hypochlorite/sodium hypochlorite, sodium hypochlorite/Kenocid 2100 ® , or Kenocid 2100 ® /Kenocid 2100 ® ) for total time of 6 min or exposing it to gamma irradiation (0.6 KGy) can decrease the risk of

  11. Residues of maneb in potatoes and lettuce and their persistence during cooking, washing and uv exposition

    International Nuclear Information System (INIS)

    Bennaceur, M.; Sennaoui, Z.; Zennouche, B.; Hylin, J.W.

    1992-01-01

    Lettuce plants were treated each with 0,186 mg of 14C maneb and 1,86 mg unlabelled maneb. The plants were analyzed 30 days later and subjected to washing. Washing eliminates 17,46% of total 14C maneb applied. No Etu was observed in water.Washing and baking cause a significant decrease of EBDC in potatoes samples and the UV exposition involves a decrease of the fungicide and a formation of Etu. On the other hand 54 % and 38% of lettuce and potatoe samples analyzed by CS2 method exceed the authorized norms

  12. Low-dose irradiation of cut iceberg lettuce in modified atmosphere packaging

    International Nuclear Information System (INIS)

    Hagenmaier, R.D.; Baker, R.A.

    1997-01-01

    Irradiation at a mean dosage of 0.19 kGy of commercially prepared fresh-cut lettuce resulted in a product that had, 8 days after irradiation, microbial population of 290 cfu/g and yeast population of 60 cfu/g, compared with values of 220 000 and 1 400 cfu/g, respectively, for the nonirradiated control. Irradiation also caused moderate changes in respiration rate and headspace gas concentrations. It appears feasible to combine chlorination with irradiation at 0.15-0.5 kGy to produce fresh-cut, chopped lettuce with reduced microbial population

  13. Environmental modification of yield and food composition of cowpea and leaf lettuce

    Science.gov (United States)

    Mitchell, Cary A.; Nielsen, Suzanne S.; Bubenheim, David L.

    1990-01-01

    Cowpea (Vigna unguiculata (L.) Walp.) and leaf lettuce (Lactuca sativa L.) are candidate species to provide ligume protein and starch or serve as a salad base for a nutritionally balanced and psychologically satisfying vegetarian diet in the Controlled Ecology Life Support System (CELSS). Various nutritional parameters are reported. Hydroponic leaf lettuce grew best under CO2 enrichment and photosynthetic photon flux (PPF) enhancement. Leaf protein content reached 36 percent with NH4(+) + NO3 nutrition; starch and free sugar content was as high as 7 or 8.4 percent of DW, respectively, for high PPF/CO2 enriched environments.

  14. Molecular identification and biological characterization of a new potyvirus in lettuce.

    Science.gov (United States)

    Ciuffo, Marina; Mammella, Marco; Vallino, Marta; Caciagli, Piero; Turina, Massimo

    2016-09-01

    A potyvirus causing necrosis and leaf distortion on lettuce was found in the Lazio region of Italy. Host range analysis showed its ability to infect only Chenopodium quinoa and C. amaranticolor in addition to some lettuce cultivars. The virus could be transmitted by aphids of the species Myzus persicae. The complete 9829-nt genome was characterized. BLAST analysis of sequence of the complete encoded polyprotein showed that the most closely related virus is asparagus virus 1, with 52 % amino acid sequence identity. These results suggest that this virus should be considered a member of a new species in the genus Potyvirus.

  15. Sensory shelf life estimation of minimally processed lettuce considering two stages of consumers' decision-making process.

    Science.gov (United States)

    Ares, Gastón; Giménez, Ana; Gámbaro, Adriana

    2008-01-01

    The aim of the present work was to study the influence of context, particularly the stage of the decision-making process (purchase vs consumption stage), on sensory shelf life of minimally processed lettuce. Leaves of butterhead lettuce were placed in common polypropylene bags and stored at 5, 10 and 15 degrees C. Periodically, a panel of six assessors evaluated the appearance of the samples, and a panel of 40 consumers evaluated their appearance and answered "yes" or "no" to the questions: "Imagine you are in a supermarket, you want to buy a minimally processed lettuce, and you find a package of lettuce with leaves like this, would you normally buy it?" and "Imagine you have this leaf of lettuce stored in your refrigerator, would you normally consume it?". Survival analysis was used to calculate the shelf lives of minimally processed lettuce, considering both decision-making stages. Shelf lives estimated considering rejection to purchase were significantly lower than those estimated considering rejection to consume. Therefore, in order to be conservative and assure the products' quality, shelf life should be estimated considering consumers' rejection to purchase instead of rejection to consume, as traditionally has been done. On the other hand, results from logistic regressions of consumers' rejection percentage as a function of the evaluated appearance attributes suggested that consumers considered them differently while deciding whether to purchase or to consume minimally processed lettuce.

  16. Quality of fresh-cut Iceberg lettuce and spinach irradiated at doses up to 4 kGy

    International Nuclear Information System (INIS)

    Fan Xuetong; Guan Wenqiang; Sokorai, Kimberly J.B.

    2012-01-01

    Fresh-cut Iceberg lettuce packaged in modified atmosphere packages and spinach in perforated film bags were irradiated with gamma rays at doses of 0, 1, 2, 3, and 4 kGy. After irradiation, the samples were stored for 14 days at 4 °C. O 2 levels in the packages of fresh-cut Iceberg lettuce decreased and CO 2 levels increased with increasing radiation dose, suggesting that irradiation increased respiration rates of lettuce. Tissue browning of irradiated cut lettuce was less severe than that of non-irradiated, probably due to the lower O 2 levels in the packages. However, samples irradiated at 3 and 4 kGy had lower maximum force and more severe sogginess than the non-irradiated control. In addition, ascorbic acid content of irradiated lettuce was 22–40% lower than the non-irradiated samples after 14 days of storage. The visual appearance of spinach was not affected by irradiation even at a dose of 4 kGy. Consumer acceptance suggested that more people would dislike and would not buy spinach that was treated at 3 and 4 kGy as compared to the non-irradiated sample. Overall, irradiation at doses of 1 and 2 kGy may be employed to enhance microbial safety of fresh-cut Iceberg lettuce and spinach while maintaining quality. - Highlights: ▶ Headspace composition in the modified atmosphere packages of cut lettuce was affected by irradiation. ▶ Fresh-cut lettuce in adapted atmosphere could tolerate 1 or 2 kGy rays without quality deterioration in look and texture. ▶ Lettuce irradiated at doses higher than 2 kGy developed sogginess. ▶ Irradiated spinach maintained a good appearance at doses of 3 and 4 kGy. ▶ Higher doses (3 and 4 kGy) of radiation decreased consumers' likingness and purchase intent of irradiated spinach.

  17. Differential distribution of cadmium in lettuce (Lactuca sativa L.) and maize (Zea mays L.)

    NARCIS (Netherlands)

    Florijn, P.J.

    1993-01-01

    Large genotypic variation in shoot Cd concentrations has been reported in literature for several plant species including lettuce ( Lactuca sativa L.) and maize ( Zea mays L.). The objective of this thesis was to elucidate the physiological andlor

  18. Semi-high throughput screening for potential drought-tolerance in lettuce (Lactuca sativa) germplasm collections

    Science.gov (United States)

    This protocol describes a method by which a large collection of the leafy green vegetable lettuce (Lactuca sativa L.) germplasm was screened for likely drought-tolerance traits. Fresh water availability for agricultural use is a growing concern across the United States as well as many regions of th...

  19. Rapid identification of lettuce seed germination mutants by bulked segregant analysis and whole genome sequencing.

    Science.gov (United States)

    Huo, Heqiang; Henry, Isabelle M; Coppoolse, Eric R; Verhoef-Post, Miriam; Schut, Johan W; de Rooij, Han; Vogelaar, Aat; Joosen, Ronny V L; Woudenberg, Leo; Comai, Luca; Bradford, Kent J

    2016-11-01

    Lettuce (Lactuca sativa) seeds exhibit thermoinhibition, or failure to complete germination when imbibed at warm temperatures. Chemical mutagenesis was employed to develop lettuce lines that exhibit germination thermotolerance. Two independent thermotolerant lettuce seed mutant lines, TG01 and TG10, were generated through ethyl methanesulfonate mutagenesis. Genetic and physiological analyses indicated that these two mutations were allelic and recessive. To identify the causal gene(s), we applied bulked segregant analysis by whole genome sequencing. For each mutant, bulked DNA samples of segregating thermotolerant (mutant) seeds were sequenced and analyzed for homozygous single-nucleotide polymorphisms. Two independent candidate mutations were identified at different physical positions in the zeaxanthin epoxidase gene (ABSCISIC ACID DEFICIENT 1/ZEAXANTHIN EPOXIDASE, or ABA1/ZEP) in TG01 and TG10. The mutation in TG01 caused an amino acid replacement, whereas the mutation in TG10 resulted in alternative mRNA splicing. Endogenous abscisic acid contents were reduced in both mutants, and expression of the ABA1 gene from wild-type lettuce under its own promoter fully complemented the TG01 mutant. Conventional genetic mapping confirmed that the causal mutations were located near the ZEP/ABA1 gene, but the bulked segregant whole genome sequencing approach more efficiently identified the specific gene responsible for the phenotype. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  20. Effects of PSAG12-IPT gene expression on development and senescence in transgenic Lettuce

    NARCIS (Netherlands)

    McCabe, M.S.; Garratt, L.C.; Schepers, F.; Jordi, W.J.R.M.; Stoopen, G.M.; Davelaar, E.; Rhijn, van J.H.A.; Power, J.B.; Davey, M.R.

    2001-01-01

    An ipt gene under control of the senescence-specific SAG12 promoter from Arabidopsis (PSAG12-IPT) significantly delayed developmental and postharvest leaf senescence in mature heads of transgenic lettuce (Lactuca sativa L. cv Evola) homozygous for the transgene. Apart from retardation of leaf

  1. Ultrasound as an intervention technology for the sanitation of lettuce harvesting knife

    Science.gov (United States)

    Lettuce field-coring and trimming practices are recent industry developments designed to improve fresh-cut processing yield and reduce shipping and waste disposal costs. Studies showed that the harvesting/coring knives used could be potentially contaminated with pathogens by contact with contaminat...

  2. Low-cost multispectral imaging for remote sensing of lettuce health

    Science.gov (United States)

    Ren, David D. W.; Tripathi, Siddhant; Li, Larry K. B.

    2017-01-01

    In agricultural remote sensing, unmanned aerial vehicle (UAV) platforms offer many advantages over conventional satellite and full-scale airborne platforms. One of the most important advantages is their ability to capture high spatial resolution images (1-10 cm) on-demand and at different viewing angles. However, UAV platforms typically rely on the use of multiple cameras, which can be costly and difficult to operate. We present the development of a simple low-cost imaging system for remote sensing of crop health and demonstrate it on lettuce (Lactuca sativa) grown in Hong Kong. To identify the optimal vegetation index, we recorded images of both healthy and unhealthy lettuce, and used them as input in an expectation maximization cluster analysis with a Gaussian mixture model. Results from unsupervised and supervised clustering show that, among four widely used vegetation indices, the blue wide-dynamic range vegetation index is the most accurate. This study shows that it is readily possible to design and build a remote sensing system capable of determining the health status of lettuce at a reasonably low cost (lettuce growers.

  3. Structural and Sensory Characterization of Novel Sesquiterpene Lactones from Iceberg Lettuce.

    Science.gov (United States)

    Mai, Franziska; Glomb, Marcus A

    2016-01-13

    Lactuca sativa var. capitate (iceberg lettuce) is a delicious vegetable and popular for its mild taste. Nevertheless, iceberg lettuce is a source of bitter substances, such as the sesquiterpene lactones. Chemical investigations on the n-butanol extract led to the isolation of three novel sesquiterpene lactones. All compounds were isolated by multilayer countercurrent chromatography followed by preparative high-performance liquid chromatography. The structures were verified by means of spectroscopic methods, including NMR and mass spectrometry techniques. For the first time 11ß,13-dihydrolactucin-8-O-sulfate (jaquinelin-8-O-sulfate) was structurally elucidated and identified in plants. In addition, the sesquiterpene lactones cichorioside B and 8-deacetylmatricarin-8-O-sulfate were identified as novel ingredients of iceberg lettuce. Further flowering plants in the daisy family Asteraceae were examined for the above three compounds. At least one of the compounds was identified in nine plants. The comparison between the lettuce butt end and the leaves of five types of the Cichorieae tribe showed an accumulation of the compounds in the butt end. Further experiments addressed the impact of sesquiterpene lactones on color formation and bitter taste.

  4. Uptake of polybrominated diphenyl ethers by carrot and lettuce crops grown in compost-amended soils.

    Science.gov (United States)

    Bizkarguenaga, E; Iparraguirre, A; Oliva, E; Quintana, J B; Rodil, R; Fernández, L A; Zuloaga, O; Prieto, A

    2016-02-01

    The uptake of polybrominated diphenyl ethers (PBDEs) by carrot and lettuce was investigated. Degradation of PBDEs in soil in the absence of the plants was discarded. Different carrot (Nantesa and Chantenay) and lettuce (Batavia Golden Spring and Summer Queen) varieties were grown in fortified or contaminated compost-amended soil mixtures under greenhouse conditions. After plant harvesting, roots (core and peel) and leaves were analyzed separately for carrot, while for lettuce, leaves and hearts were analyzed together. The corresponding bioconcentration factors (BCFs) were calculated. In carrots, a concentration gradient of 2,2',3,4,4',5'-hexabromodiphenyl ether (BDE-138) became evident that decreased from the root peel via root core to the leaves. For decabromodiphenyl ether (BDE-209) at the low concentration level (7 and 20 ng g(-1)), the leaves incorporated the highest concentration of the target substance. For lettuce, a decrease in the BCF value (from 0.24 to 0.02) was observed the higher the octanol-water partition coefficient, except in the case of BDE-183 (BCF = 0.51) and BDE-209 (BCF values from 0.41 to 0.74). Significant influence of the soils and crop varieties on the uptake could not be supported. Metabolic debromination, hydroxylation or methylation of the target PBDEs in the soil-plant system was not observed.

  5. Moessbauer and EXAFS spectroscopy investigation of iron and arsenic adsorption to lettuce leaves

    International Nuclear Information System (INIS)

    Vasconcelos, Igor F.; Silva, Gabriela C.; Carvalho, Regina P.; Dantas, Maria Sylvia S.; Ciminelli, Virginia S. T.

    2010-01-01

    The accumulation of iron and arsenic from aqueous solution by lettuce leaves biomass was investigated using Moessbauer and EXAFS spectroscopic techniques. Moessbauer spectroscopy results show that iron is oxidized during sorption while EXAFS results indicate that iron is coordinated by approximately 6 oxygen and 2 carbon atoms while arsenic is coordinated by approximately 4 oxygen atoms with iron as a second neighbor.

  6. PRODUCTION OF LETTUCE UNDER GREEN MANURING WITH Calotropis procera IN TWO CULTIVATION SEASONS

    Directory of Open Access Journals (Sweden)

    ÊNIO GOMES FLÔR SOUZA

    2017-01-01

    Full Text Available The production of vegetable crops is characterized by intensive land use, high input demands and the requirement of strategic management adoption with an agro - ecological approach. In this study, agronomic indicators were evaluated in lettuce fertilized with different amounts of roostertree biomass; fertilizer was incorporated into the soil at distinct times and seedlings were planted in two cropping seasons (spring and autumn - winter in Serra Talhada, Pernambuco state, Brazil. The experimental design consisted of randomized complete blocks with three replications and treatments arranged in a 4 x 4 factorial scheme. The first factor was the amounts of roostertree biomass (5.4, 8.8, 12.2, and 15.6 t ha - 1 on a dry basis and the second the manure incorporation times (0, 10, 20, and 30 days before lettuce transplanting. The variables evaluated in the lettuce crop were: plant height and diameter, number of leaves per plant, productivity of green mass, and dry shoot mass. Maximum productivity and dry shoot mass were obtained using fertilization with 15.6 t ha - 1 . A synchrony between supply of nutrients by green manure and the period of maximum demand by lettuce was observed in the incorporation times of 10 (spring and 20 (autumn - winter days before transplanting. Cultivation in the spring resulted in higher vegetative growth.

  7. Moessbauer and EXAFS spectroscopy investigation of iron and arsenic adsorption to lettuce leaves

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Igor F., E-mail: ifvasco@ufc.br [Universidade Federal do Ceara, Dep. Eng. Metalurgica e de Materiais (Brazil); Silva, Gabriela C.; Carvalho, Regina P.; Dantas, Maria Sylvia S.; Ciminelli, Virginia S. T. [Universidade Federal de Minas Gerais, Dep. Eng. Metalurgica e de Materiais (Brazil)

    2010-01-15

    The accumulation of iron and arsenic from aqueous solution by lettuce leaves biomass was investigated using Moessbauer and EXAFS spectroscopic techniques. Moessbauer spectroscopy results show that iron is oxidized during sorption while EXAFS results indicate that iron is coordinated by approximately 6 oxygen and 2 carbon atoms while arsenic is coordinated by approximately 4 oxygen atoms with iron as a second neighbor.

  8. Experimental study and process parameters analysis on the vacuum cooling of iceberg lettuce

    Energy Technology Data Exchange (ETDEWEB)

    He, Su-Yan [School of Mechanical and Electrical Engineering, Qingdao University, Qingdao 266071 (China); Li, Yun-Fei [Department of Food Science and Engineering, School of Agriculture and Biology, Shanghai Jiao Tong University (China)

    2008-10-15

    The vacuum cooling of iceberg lettuce was described in this paper. Based on the energy and mass balance, a mathematical model was developed to analyze the performance of the vacuum cooler and the evaporation-boiling phenomena during vacuum cooling of iceberg lettuce. The temporal trends of total system pressure, produce temperature such as surface temperature, center temperature, mass-average temperature, the weight loss of iceberg lettuce during vacuum cooling were predicted. Validation experimentation is achieved in the designed vacuum cooler. The experimental data were compared with the simulation results. It was found that the differences of the temperature between the simulation and the experiments were within 1{sup o}C. The amount of water evaporated from the iceberg lettuce by simulation was 3.32% during the whole vacuum cooling, while the tested water loss rate was 2.97%, the maximal deviation of weight loss was within 0.59%. The simulation results agreed well with the experimental data. (author)

  9. Simulation of gamma-ray irradiation of lettuce leaves in a 137Cs irradiator using MCNP

    International Nuclear Information System (INIS)

    Kim, Jongsoon; Moreira, Rosana G.; Braby, Leslie A.

    2010-01-01

    Ionizing radiation effectively reduces the number of common microbial pathogens in fresh produce. However, the efficacy of the process for pathogens internalized into produce tissue is unknown. The objective of this study was to understand gamma irradiation of lettuce leaf structure exposed in a 137 Cs irradiator using MCNP. The simulated 137 Cs irradiator is a self-shielded device, and its geometry and sources are described in the MCNP input file. When the irradiation chamber is filled with water, lower doses are found at the center of the irradiation volume and the dose uniformity ratio (maximum dose/minimum dose) is 1.76. For randomly oriented rectangular lettuce leaf segments in the irradiation chamber, the dose uniformity ratio is 1.25. It shows that dose uniformity in the Cs irradiator is strongly dependent of the density of the sample. To understand dose distribution inside the leaf, we divided a lettuce leaf into a low density (flat) region (0.72 g/cm 3 ) and high density (rib) region (0.86 g/cm 3 ). Calculated doses to the rib are 61% higher than doses to the flat region of the leaf. This indicates that internalized microorganisms can be inactivated more easily than organisms on the surface. This study shows that irradiation can effectively reduce viable microorganism internalized in lettuce. (author)

  10. Robust production of virus-like particles and monoclonal antibodies with geminiviral replicon vectors in lettuce

    Science.gov (United States)

    Lai, Huafang; He, Junyun; Engle, Michael; Diamond, Michael S.; Chen, Qiang

    2011-01-01

    Summary Pharmaceutical protein production in plants has been greatly promoted by the development of viral-based vectors and transient expression systems. Tobacco and related Nicotiana species are currently the most common host plants for generation of plant-made pharmaceutical proteins (PMPs). Downstream processing of target PMPs from these plants, however, is hindered by potential technical and regulatory difficulties due to the presence of high levels of phenolics and toxic alkaloids. Here, we explored the use of lettuce, which grows quickly yet produces low levels of secondary metabolites, and viral vector-based transient expression systems to develop a robust PMP production platform. Our results showed that a geminiviral replicon system based on the bean yellow dwarf virus permits high-level expression in lettuce of virus-like particles (VLP) derived from the Norwalk virus capsid protein and therapeutic monoclonal antibodies (mAbs) against Ebola and West Nile viruses. These vaccine and therapeutic candidates can be readily purified from lettuce leaves with scalable processing methods while fully retaining functional activity. Furthermore, this study also demonstrated the feasibility of using commercially produced lettuce for high-level PMP production. This allows our production system to have access to unlimited quantities of inexpensive plant material for large-scale production. These results establish a new production platform for biological pharmaceutical agents that is effective, safe, low-cost, and amenable to large-scale manufacturing. PMID:21883868

  11. Acinetobacter lactucae sp. nov., isolated from iceberg lettuce (Asteraceae: Lactuca sativa)

    Science.gov (United States)

    Strain NRRL B-41902 and three closely related strains were isolated from iceberg lettuce. The strain was found to consist of strictly aerobic, gram-negative rods that formed cocci in late stationary phase. Subsequent to sequencing the 16S ribosomal RNA gene, it was found that strain NRRL B-41902 was...

  12. Effect of residual monomer from polyacrylamide on head lettuce grown in peat substrate.

    Science.gov (United States)

    Mroczek, Ewelina; Kleiber, Tomasz; Konieczny, Piotr; Waśkiewicz, Agnieszka

    2015-01-01

    The paper investigates the migration of the acrylamide monomer (AMD) to lettuce chosen as a test plant growing in an organic medium (peat substrate). Polyacrylamide (PAM)-based flocculant added to the growing medium contained no more than 1000 mg kg(-1) of AMD. Plants were grown with varied doses of PAM preparation (0.5-3.0 mg dm(-3) of peat substrate) to compare the results with the control sample. The determination of AMD content, chlorophyll content, weight of the lettuce head, and also analysis of macro- and micro-elements in lyophilised test material was made under the same analytical conditions. The results showed that lettuce plants absorb AMD to the leaves from the peat substrate. The AMD uptake has a negative impact on the growth of lettuce. It reduces the average fresh weight of heads and destabilises the mineral composition of the plant. Therefore, concern related to the transfer risk of the residual AMD from sludge used for organic fertilisation of edible plants still remains a crucial question from a food and consumer safety point of view. To ensure consumer safety, the fate of the AMD following the application of PAM to cropland should be carefully monitored in the whole food chain.

  13. Release of three iceberg lettuce populations that combined resistance to two soil borne diseases

    Science.gov (United States)

    The Agricultural Research Service, United States Department of Agriculture and the University of California, Davis, announce the release of three F2:4 breeding populations of iceberg lettuce (Lactuca sativa L.). The breeding populations combine the cor and Verticillium resistance 1 (Vr1) loci to co...

  14. Cytogenetic changes in cells of lettuce seedlings after expesure to accelerated 12C ions

    International Nuclear Information System (INIS)

    Vikhrov, A.I.; Kovalev, E.E.; Maksimova, E.N.; Nevzgodina, L.V.; Potapov, Yu.V.

    1985-01-01

    In this report the data are presented on the incidence of aberrant cells in lettuce seedlings after the effect of 12 C ions depending on the number of hits. Determined were the number of particles passed through the biological object and the values of doses received by each seed with regard for the secondary irradiation contribution to these doses are determined

  15. Breeding and genetics of lettuce for resistance against race 2 Verticillium wilt

    Science.gov (United States)

    Verticillium wilt, caused by Verticillium dahliae Kleb., is an economically important disease of lettuce in central coastal California. Most isolates of the pathogen detected in the Salinas Valley belong to race 1 for which complete resistance exists. However, adequate level of resistance is not ava...

  16. Bacon, Lettuce and Tomato: een strategie om leerlingen te helpen hun antwoorden op examenvragen te verbeteren

    NARCIS (Netherlands)

    Kneppers, L.

    2014-01-01

    In Tutor2u las ik dat in een workshop een strategie was besproken om leerlingen te helpen hun examenantwoorden vollediger en juister te formuleren. De strategie heet in Groot Brittannië BLT, voor leerlingen daar gemakkelijk te onthouden vanwege de populaire Bacon, Lettuce en Tomato sandwich.

  17. A STUDY ON THE ACCUMULATION OF PERCHLORATE IN YOUNG HEAD LETTUCE

    Science.gov (United States)

    The overall objective of this study was to demonstrate in a greenhouse study the potential for incorporation of perchlorate from aqueous solutions of 10, 50, 100, 500, 1,000, 5,000, and 10,000 ppb into an agricultural food crop (lettuce; Lactuca sativa), which is typically grown ...

  18. Complete genome sequence of a divergent strain of lettuce chlorosis virus from Periwinkle in China

    Science.gov (United States)

    A novel strain of Lettuce chlorosis virus (LCV) was identified from periwinkle in China (PW) with foliar interveinal chlorosis and plant dwarfing. Complete nucleotide (nt) sequences of genomic RNA1 and RNA2 of the virus are 8,602 nt and 8,456 nt, respectively. The genomic organization of LCV-PW rese...

  19. Genomic and environmental selection patterns in two distinct lettuce crop-wild hybrid crosses

    NARCIS (Netherlands)

    Hartman, Y.; Uwimana, B; Hooftman, D.A.P.; Schranz, M.E.; van de Wiel, C.C.M.; Smulders, M.J.M.; Visser, R.G.F.; van Tienderen, P.H.

    2013-01-01

    Genomic selection patterns and hybrid performance influence the chance that crop (trans)genes can spread to wild relatives. We measured fitness(-related) traits in two different field environments employing two different crop-wild crosses of lettuce. We performed quantitative trait loci (QTL)

  20. Genomic and environmental selection patterns in two distinct lettuce crop-wild hybrid crosses

    NARCIS (Netherlands)

    Hartman, Y.; Uwimana, B.; Hooftman, D.A.P.; Schranz, M.E.; Wiel, van de C.C.M.; Smulders, M.J.M.; Visser, R.G.F.; Tienderen, van P.H.

    2013-01-01

    Genomic selection patterns and hybrid performance influence the chance that crop (trans)genes can spread to wild relatives. We measured fitness(-related) traits in two different field environments employing two different crop–wild crosses of lettuce. We performed quantitative trait loci (QTL)

  1. Genes up-regulated during red coloration in UV-B irradiated lettuce leaves.

    Science.gov (United States)

    Park, Jong-Sug; Choung, Myoung-Gun; Kim, Jung-Bong; Hahn, Bum-Soo; Kim, Jong-Bum; Bae, Shin-Chul; Roh, Kyung-Hee; Kim, Yong-Hwan; Cheon, Choong-Ill; Sung, Mi-Kyung; Cho, Kang-Jin

    2007-04-01

    Molecular analysis of gene expression differences between green and red lettuce leaves was performed using the SSH method. BlastX comparisons of subtractive expressed sequence tags (ESTs) indicated that 7.6% of clones encoded enzymes involved in secondary metabolism. Such clones had a particularly high abundance of flavonoid-metabolism proteins (6.5%). Following SSH, 566 clones were rescreened for differential gene expression using dot-blot hybridization. Of these, 53 were found to overexpressed during red coloration. The up-regulated expression of six genes was confirmed by Northern blot analyses. The expression of chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), and dihydroflavonol 4-reductase (DFR) genes showed a positive correlation with anthocyanin accumulation in UV-B-irradiated lettuce leaves; flavonoid 3',5'-hydroxylase (F3',5'H) and anthocyanidin synthase (ANS) were expressed continuously in both samples. These results indicated that the genes CHS, F3H, and DFR coincided with increases in anthocyanin accumulation during the red coloration of lettuce leaves. This study show a relationship between red coloration and the expression of up-regulated genes in lettuce. The subtractive cDNA library and EST database described in this study represent a valuable resource for further research for secondary metabolism in the vegetable crops.

  2. Detection of decay in fresh-cut lettuce using hyperspectral imaging and chlorophyll fluorescence imaging

    Science.gov (United States)

    Fresh-cut lettuce sold in modified atmosphere packaging (MAP) is a desirable, but highly perishable product. Decay of tissue can start a few days after processing and may be difficult to detect by quick visual observation. A system for early detection of decay and gradual evaluation of its progress ...

  3. Alkylperoxyl radical scavenging activity of red leaf lettuce (Lactuca sativa L.) phenolics.

    Science.gov (United States)

    Caldwell, Charles R

    2003-07-30

    Although lettuce may provide relatively low levels of antioxidative phytochemicals which may contribute to human health, lettuce leaf extracts in fact contained compounds with high specific peroxyl radical scavenging activities. After determining the extraction conditions that minimized phenolic oxidation and produced the highest oxygen radical absorbance capacity (ORAC) values, the phenolic compounds from red leaf lettuce were separated by reverse-phase high-performance liquid chromatography (HPLC). The primary phenolic compounds in the leaf tissue extracts were mono- and dicaffeoyltartaric acid (CTA and DCTA), mono- and dicaffeoylquinic acid (CQA and DCQA), quercetin 3-malonylglucoside (QMG), quercetin 3-glucoside (QG), cyanidin 3-malonylglucoside (CMG), and an unknown phenolic ester (UPE). Significant levels of DCQA were only found after wounding. Using the new fluorescein-based ORAC assay procedures, fractions from the HPLC analyses were assayed for peroxyl radical absorbance capacity. Using absorbance to estimate concentration, the decreasing order of contribution to the total ORAC value of an extract from wounded tissue was QMG > DCQA > CMG > DCTA > UPE > QG > CTA. The decreasing order of the specific peroxyl radical scavenging activities was CMG > QG > DCTA > DCQA > QMG > UPE > CQA > CTA. Since the concentrations of plant flavonoid and phenolic acid esters are sensitive to environmental factors, this information may be used to develop pre- and postharvest conditions which increase the dietary benefits of leaf lettuce.

  4. Bacterial population dynamics and sensorial quality loss in modified atmosphere packed fresh-cut iceberg lettuce

    NARCIS (Netherlands)

    Paillart, M.J.M.; Vossen, J.M.B.M.; Levin, E.; Lommen, E.; Otma, E.C.; Snels, J.C.M.A.; Woltering, E.J.

    2017-01-01

    The end of shelf life of fresh-cut iceberg lettuce packed in modified atmosphere (MA) is determined by its visual quality and by its microbial load. The total microbial load should not exceed 6–7 log CFU g−1 mesophilic counting and be free of human pathogens. Not much is known about specific

  5. Rhizoctonia solani as a component in the bottom rot complex of glasshouse lettuce

    NARCIS (Netherlands)

    Kooistra, T.

    1983-01-01

    The basal parts of maturing glasshouse lettuce can be attacked by several soil fungi, which cause bottom rot. Until recently quintozene was generally applied against this disease complex. The study of the causal fungi - especially Rhizoctonia solani - and their control was

  6. Uptake of perfluorinated alkyl acids by hydroponically grown lettuce (Lactuca sativa)

    NARCIS (Netherlands)

    Felizeter, S.; McLachlan, M.; de Voogt, P.

    2012-01-01

    An uptake study was carried out to assess the potential human exposure to perfluorinated alkyl acids (PFAAs) through the ingestion of vegetables. Lettuce (Lactuca sativa) was grown in PFAA-spiked nutrient solutions at four different concentrations, ranging from 10 ng/L to 10 μg/L. Eleven

  7. Red leaf lettuce breeding line with resistance to corky root, 06-810

    Science.gov (United States)

    The Agricultural Research Service, United States Department of Agriculture (USDA) announces the release of a breeding line of red leaf lettuce (Lactuca sativa L.), 06-810. The line may be suitable for commercial production, and is suitable for use as a source of resistance to corky root disease in t...

  8. Germplasm Management in the Post-genomics Era-a case study with lettuce

    Science.gov (United States)

    High-throughput genotyping platforms and next-generation sequencing technologies revolutionized our ways in germplasm characterization. In collaboration with UC Davis Genome Center, we completed a project of genotyping the entire cultivated lettuce (Lactuca sativa L.) collection of 1,066 accessions ...

  9. A rapid and efficient in vitro regeneration system for lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Armas, Isabel; Pogrebnyak, Natalia; Raskin, Ilya

    2017-01-01

    Successful biotechnological improvement of crop plants requires a reliable and efficient in vitro regeneration system. Lettuce ( Lactuca sativa L.), one the most important vegetable crops worldwide, is strongly genotype-dependent in terms of regeneration capacity, limiting the potential for biotechnological improvement of cultivars which show recalcitrance under currently available protocols. The effect of different nutrient sources, plant hormone combinations and activated charcoal supplementation on shoot induction efficiency was evaluated on the cultivar 'RSL NFR', which had previously shown poor regeneration efficiency. Multiple shoot organogenesis from cotyledon explants was recorded at the highest frequency and speed on Murashige and Skoog regeneration medium supplemented with 200 mg/l of activated charcoal, 3% sucrose, 10 mg/l benzylaminopurine and 0.5 mg/l naphthaleneacetic acid, which induced shoots through direct regeneration in 90.8 ± 7.9% of explants. High shoot induction efficiency was also observed, albeit not quantified, when using this medium on some other cultivars. This activated charcoal-containing regeneration medium might offer a rapid and efficient option for direct shoot induction in some lettuce genotypes that do not respond well to common lettuce regeneration protocols. This is also the first report of the effect of activated charcoal in lettuce tissue culture.

  10. LETTUCE AND BROCCOLI RESPONSE AND SOIL PROPERTIES RESULTING FROM TANNERY WASTE APPLICATIONS

    Science.gov (United States)

    Broccoli (Brassica oleracea L. var. italica) and lettuce (Lactuca sativa L.) were grown on Willamette sil (Pachic Ultic Argixerolls) amended 1 and 2 yr earlier with chrome tannery wastes at rates up to 192 Mg ha to determine nutrient and trace element availability. Soils were sam...

  11. The development of an economic threshold for Nasonovia ribisnigri (Hemiptera: Aphididae) on lettuce in central Spain.

    Science.gov (United States)

    Morales, Ignacio; Diaz, Beatriz María; Hermoso de Mendoza, Alfonso; Nebreda, Miguel; Fereres, Alberto

    2013-04-01

    This study reports economic thresholds for the lettuce aphid Nasonovia ribisnigri (Mosley), based exclusively on cosmetic damage, that is, presence or absence of aphids at harvest time. Field trials were conducted in La Poveda Experimental Farm, Madrid (Spain) during autumn (2004 and 2005) and spring (2005 and 2006). Plants were arranged in plots and just before the formation of lettuce hearts they were infested with different densities of N. ribisnigri. Two days later, half of each plot was treated with tau-fluvalinate (Klartan24AF) and the other half remained as an untreated control. Economic thresholds were obtained from nonlinear regressions calculated between the percentage of commercial plants at the end of the crop cycle for both, treated and untreated semiplots, and the different initial densities of N. ribisnigri per plant. Two criteria were used to consider a commercial lettuce plant: a conservative estimate (0 aphids/plant) and a lax one (aphids/plant). Thus, an economic threshold was established for each season and criterium. The economic thresholds that were obtained with the most and least conservative criteria were in spring 0.06 and 0.12 aphids per plant, and in autumn 0.07 and 0.13 aphids per plant, respectively. These results show that to avoid cosmetic damage, insecticide sprays are required when a very low aphid density is detected in lettuce seedlings soon after transplant.

  12. Effect of stale seedbed preparations and subsequent weed control in lettuce (cv. Iceboll) on weed densities

    NARCIS (Netherlands)

    Riemens, M.M.; Weide, van der R.Y.; Bleeker, P.O.; Lotz, L.A.P.

    2007-01-01

    The effects of stale seedbed preparations and several weed control methods on the emergence of weeds in lettuce were studied. The specific goal was to evaluate the use of a stale seedbed in combination with chemical or mechanical weed control methods in the field. Depending on location and year,

  13. Changes in the physico-chemical properties of four lettuce (Lactuca sativa L. varieties during storage

    Directory of Open Access Journals (Sweden)

    María Vargas-Arcila

    2017-05-01

    Full Text Available Lettuce, a popularly consumed leafy vegetable, is well known for its health and nutritional value. Thus, the current study focused on the qualitative changes of four lettuce varieties, namely Alpha, Parris Island, Graziella and Lollo Rossa, stored at 5.5 ºC and 90 % RH for 12 days. The analyzed parameters were water content, total soluble solids (TSS, titrable acidity (TA, vitamin C, total phenols, polyphenoloxidase (PPO, color and texture. Under storage conditions, the studied varieties exhibited different rates of water loss. TSS was found to increase until day 8 of storage, which is also when TA differences were observed. The Graziella variety showed the highest vitamin C levels. Total phenol content decreased significantly during the 12 days of storage. No significant PPO activity changes were found, except for those of the Lollo Rossa variety. Biplot analysis allowed observing not only positive and negative correlations between coordinates L*, a* and b*, but also the separavtion of the green lettuce varieties from the red one, together with color variations depending on leaf position. Although textural changes were recorded at the end of the study, foliage quality was not altered. In short, the studied parameters, which contribute to lettu-ce direct consumption properties, can be said to be variety-dependent and better preserved under refrigeration.

  14. Pesticide Residues in Commercial Lettuce, Onion, and Potato Samples From Bolivia—A Threat to Public Health?

    DEFF Research Database (Denmark)

    Skovgaard, Marlene; Renjel, Susana; Jensen, Olaf Chresten

    2017-01-01

    lettuce samples from La Paz were sampled on August 15, 2015 at a local market and screened for 283 pesticides. Residues of cypermethrin, chlorpyrifos, difenoconazol, or/and λ-cyhalothrin were detected in 50% of the lettuce samples, whereas no pesticides were found in potatoes and onions. In 20......% of the lettuce samples, the measurements were above the maximum residue limits, and 2 or 3 pesticides were identified simultaneously. Washing almost halved the pesticide levels, but still 20% of the samples showed measurements above the limits. No samples contained concentrations of pesticides which alone...

  15. Influence of nitrogen and phosphorus sources on mycorrhizal lettuces under organic farming

    Science.gov (United States)

    Scotti, Riccardo; Seguel, Alex; Cornejo, Pablo; Rao, Maria A.; Borie, Fernando

    2010-05-01

    Arbuscular mycorrhizal fungi (AMF) develop symbiotic associations with plants roots. These associations are very common in the natural environment and can provide a range of benefits to the host plant. AMF improve nutrition, enhance resistance to soil-borne pests and disease, increase resistance to drought and tolerance to heavy metals, and contribute to a better soil structure. However, agricultural intensive managements, such as the use of mineral fertilizes, pesticides, mouldboard tillage, monocultures and use of non-mycorrhizal crops, are detrimental to AMF. As a consequence, agroecosystems are impoverished in AMF and may not provide the full range of benefits to the crop. Organic farming systems may be less unfavourable to AMF because they exclude the use of water-soluble fertilisers and most pesticides, and generally they plan diverse crop rotations. The AMF develop the most common type of symbiosis in nature: about 90% of the plants are mycorrhizal and many agricultural crops are mycorrhizal. One of more mycorrhizal crops is lettuce, that is very widespread in intensive agricultural under greenhouse. Therefore, cultivated lettuce is know to be responsive to mycorrhizal colonization which can reach 80% of root length and contribute to phosphorus and nitrogen absorption by this plant specie. For this work four different lettuce cultivars (Romana, Milanesa, Grande Lagos and Escarola) were used to study mycorrhization under organic agricultural system, supplying compost from agricultural waste (1 kg m-2) as background fertilization for all plots, red guano as phosphorus source (75 U ha-1 and 150 U ha-1 of P2O5), lupine flour as nitrogen source (75 and 150 U/ha of N) and a combination of both. Lettuce plants were cultivated under greenhouse and after two months of growing, plants were harvested and dried and fresh weight of lettuce roots and shoots were evaluated. The number of spores, percentage of colonization, total mycelium and glomalin content were also

  16. Lettuce irrigated with contaminated water: Photosynthetic effects, antioxidative response and bioaccumulation of microcystin congeners.

    Science.gov (United States)

    Bittencourt-Oliveira, Maria do Carmo; Cordeiro-Araújo, Micheline Kézia; Chia, Mathias Ahii; Arruda-Neto, João Dias de Toledo; de Oliveira, Ênio Tiago; dos Santos, Flávio

    2016-06-01

    The use of microcystins (MCs) contaminated water to irrigate crop plants represents a human health risk due to their bioaccumulation potential. In addition, MCs cause oxidative stress and negatively influence photosynthetic activities in plants. The present study was aimed at investigating the effect of MCs on photosynthetic parameters and antioxidative response of lettuce. Furthermore, the bioaccumulation factor (BAF) of total MCs, MC-LR and MC-RR in the vegetable after irrigation with contaminated water was determined. Lettuce crops were irrigated for 15 days with water containing cyanobacterial crude extracts (Microcystis aeruginosa) with MC-LR (0.0, 0.5, 2.0, 5.0 and 10.0 µg L(-1)), MC-RR (0.0, 0.15, 0.5, 1.5 and 3.0 µg L(-1)) and total MCs (0.0, 0.65, 2.5, 6.5 and 13.0 µg L(-1)). Increased net photosynthetic rate, stomatal conductance, leaf tissue transpiration and intercellular CO2 concentration were recorded in lettuce exposed to different MCs concentrations. Antioxidant response showed that glutathione S-transferase activity was down-regulated in the presence of MCs. On the other hand, superoxide dismutase, catalase and peroxidase activities were upregulated with increasing MCs concentrations. The bioaccumulation factor (BAF) of total MCs and MC-LR was highest at 6.50 and 5.00 µg L(-1), respectively, while for MC-RR, the highest BAF was recorded at 1.50 µg L(-1) concentration. The amount of total MCs, MC-LR and MC-RR bioacumulated in lettuce was highest at the highest exposure concentrations. However, at the lowest exposure concentration, there were no detectable levels of MC-LR, MC-RR and total MCs in lettuce. Thus, the bioaccumulation of MCs in lettuce varies according to the exposure concentration. In addition, the extent of physiological response of lettuce to the toxins relies on exposure concentrations. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Reduction of Escherichia coli 0157:H7 in shredded iceberg lettuce by chlorination and gamma irradiation

    International Nuclear Information System (INIS)

    Foley, D.M.; Dufour, A.; Rodriguez, L.; Caporaso, F.; Prakash, A.

    2002-01-01

    Lettuce was inoculated with a six-strain cocktail of acid-adapted Escherichia coli 0157:H7 at a level of 1x10 7 CFU/g. Following chlorination at 200 μg/ml, the lettuce was irradiated at 0.15, 0.38, or 0.55 kGy using a 60 Co source. Survival of E. coli 0157:H7, aerobic mesophiles and yeast and molds were measured over a period of 10 days. For quality analysis, chlorinated lettuce was subjected to irradiation at 0.33 and 0.53 kGy and stored at 1.0 deg. C, 4.0 deg. C or 7.0 deg. C. Changes in texture and color were determined by instrumental means and changes in flavor, odor, and visual quality were determined by sensory testing. Chlorination plus irradiation at 0.55 kGy produced a 5.4-log reduction in E. coli 0157:H7 levels. Chlorination alone reduced the E. coli 0157:H7 counts by 1-2 logs. Irradiation at 0.55 kGy was also effective in reducing standard plate counts and yeast and mold counts. Irradiation at this level did not cause softening of lettuce and sensory attributes were not adversely affected. In general, appearance and flavor were affected more by the length of storage than by temperature conditions. The 5+log reduction in E. coli counts and lack of adverse effects on sensory attributes indicate that low-dose irradiation can improve the safety and shelf-life of fresh-cut iceberg lettuce for retail sale or food service

  18. Occurrence and bioaccumulation of chemical contaminants in lettuce grown in peri-urban horticulture.

    Science.gov (United States)

    Margenat, Anna; Matamoros, Víctor; Díez, Sergi; Cañameras, Núria; Comas, Jordi; Bayona, Josep M

    2018-05-14

    Peri-urban horticulture performs environmental and socio-economic functions and provides ecological services to nearby urban areas. Nevertheless, industrialization and water pollution have led to an increase in the exposure of peri-urban vegetables to contaminants such as trace elements (TEs) and organic microcontaminants (OMCs). In this study, the occurrence of chemical contaminants (i.e., 16 TEs, 33 OMCs) in soil and lettuce leaves from 4 farm fields in the peri-urban area of the city of Barcelona was assessed. A rural site, outside the peri-urban area of influence, was selected for comparison. The concentration of TEs and OMCs ranged from non-detectable to 803 mg/kg dw and from non-detectable to 397 μg/kg dw respectively in the peri-urban soil, and from 6 · 10 -5 to 4.91 mg/kg fw and from non-detectable to 193 μg/kg fw respectively in lettuce leaves. Although the concentration of Mo, Ni, Pb, and As in the soil of the peri-urban area exceeded the environmental quality guidelines, their occurrence in lettuce complied with human food standards (except for Pb). The many fungicides (carbendazim, dimetomorph, and methylparaben) and chemicals released by plastic pipelines (tris(1-chloro-2-propyl)phosphate, bisphenol F, and 2-mercaptobenzothiazole) used in agriculture were prevalent in the soil and the edible parts of the lettuce. The occurrence of these chemical pollutants in the peri-urban area did not affect the chlorophyll, lipid, or carbohydrate content of the lettuce leaves. PCA (Principal Component Analysis) showed that soil pollution, fungicide application, and irrigation water quality are the most relevant factors determining the presence of contaminants in crops. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Reduction of Escherichia coli 0157:H7 in shredded iceberg lettuce by chlorination and gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Foley, D.M. E-mail: dfoley@chapman.edu; Dufour, A.; Rodriguez, L.; Caporaso, F.; Prakash, A

    2002-03-01

    Lettuce was inoculated with a six-strain cocktail of acid-adapted Escherichia coli 0157:H7 at a level of 1x10{sup 7} CFU/g. Following chlorination at 200 {mu}g/ml, the lettuce was irradiated at 0.15, 0.38, or 0.55 kGy using a {sup 60}Co source. Survival of E. coli 0157:H7, aerobic mesophiles and yeast and molds were measured over a period of 10 days. For quality analysis, chlorinated lettuce was subjected to irradiation at 0.33 and 0.53 kGy and stored at 1.0 deg. C, 4.0 deg. C or 7.0 deg. C. Changes in texture and color were determined by instrumental means and changes in flavor, odor, and visual quality were determined by sensory testing. Chlorination plus irradiation at 0.55 kGy produced a 5.4-log reduction in E. coli 0157:H7 levels. Chlorination alone reduced the E. coli 0157:H7 counts by 1-2 logs. Irradiation at 0.55 kGy was also effective in reducing standard plate counts and yeast and mold counts. Irradiation at this level did not cause softening of lettuce and sensory attributes were not adversely affected. In general, appearance and flavor were affected more by the length of storage than by temperature conditions. The 5+log reduction in E. coli counts and lack of adverse effects on sensory attributes indicate that low-dose irradiation can improve the safety and shelf-life of fresh-cut iceberg lettuce for retail sale or food service.

  20. Cadmium determination in lettuce grown in contaminated soil by INAAA and GFAAS

    Energy Technology Data Exchange (ETDEWEB)

    Armelin, Maria Jose A.; Maihara, Vera A.; Saiki, Mitiko, E-mail: marmelin@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Trevizam, Anderson R.; Silva, Maria Ligia S. [Universidade Estadual do Centro Oeste (UNICENTRO), Guarapuava, PR (Brazil); Muraoka, Takashi, E-mail: muraoka@cena.usp.b [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil)

    2011-07-01

    Although Cd is not essential for the mammalian organism, it follows in body the same pathways of essential elements such as zinc and copper. There is evidence that the Cd induced reduction of Ca absorption, may lead to the development of osteoporosis. Anthropogenic activities associated with industrial activities, mining and use of fertilizers, limestone pesticides in agriculture are the main sources of Cd enrichment in soils. Due to the possibility that Cd being absorbed by plants and through them to reach the food chain, interest has increased in regard to developing techniques for remediation of contaminated sites. The addition of substances capable of immobilizing the toxic elements from the soil is a procedure that has been used for remediation of contaminated sites. The function of these substances is to reduce the mobility and bioavailability of potentially toxic elements in the soil. In this study, five doses of phosphorus as triple phosphorus were used in a number of lettuce plants grown in contaminated soil. The concentration of Cd present in lettuce leaves treated with phosphate was compared with the Cd absorbed by the control plant leaves. Instrumental Neutron Activation Analysis (INAA) and Graphite-Furnace Absorption Atomic Spectrometry (GFAAS) were the analytical methods used to determine Cd contents in lettuce leaves. The objective was to evaluate the performance of the employed analytical methods: INAA and GFAAS in the assessment of the efficiency of phosphorus treatments to reduce the Cd concentrations in leaves of lettuce. Results obtained indicated that both analytical methods were efficient to discriminate the response of Cd concentration in lettuce as a function of soil treatment with phosphorus. Although INAA has shown a positive performance in this study, GFAAS seemed more appropriate because its sensitivity was much higher than that obtained by INAA, in the experimental conditions. (author)

  1. Cadmium determination in lettuce grown in contaminated soil by INAAA and GFAAS

    International Nuclear Information System (INIS)

    Armelin, Maria Jose A.; Maihara, Vera A.; Saiki, Mitiko; Trevizam, Anderson R.; Silva, Maria Ligia S.; Muraoka, Takashi

    2011-01-01

    Although Cd is not essential for the mammalian organism, it follows in body the same pathways of essential elements such as zinc and copper. There is evidence that the Cd induced reduction of Ca absorption, may lead to the development of osteoporosis. Anthropogenic activities associated with industrial activities, mining and use of fertilizers, limestone pesticides in agriculture are the main sources of Cd enrichment in soils. Due to the possibility that Cd being absorbed by plants and through them to reach the food chain, interest has increased in regard to developing techniques for remediation of contaminated sites. The addition of substances capable of immobilizing the toxic elements from the soil is a procedure that has been used for remediation of contaminated sites. The function of these substances is to reduce the mobility and bioavailability of potentially toxic elements in the soil. In this study, five doses of phosphorus as triple phosphorus were used in a number of lettuce plants grown in contaminated soil. The concentration of Cd present in lettuce leaves treated with phosphate was compared with the Cd absorbed by the control plant leaves. Instrumental Neutron Activation Analysis (INAA) and Graphite-Furnace Absorption Atomic Spectrometry (GFAAS) were the analytical methods used to determine Cd contents in lettuce leaves. The objective was to evaluate the performance of the employed analytical methods: INAA and GFAAS in the assessment of the efficiency of phosphorus treatments to reduce the Cd concentrations in leaves of lettuce. Results obtained indicated that both analytical methods were efficient to discriminate the response of Cd concentration in lettuce as a function of soil treatment with phosphorus. Although INAA has shown a positive performance in this study, GFAAS seemed more appropriate because its sensitivity was much higher than that obtained by INAA, in the experimental conditions. (author)

  2. Quantitative Microbial Risk Assessment for Escherichia coli O157:H7 in Fresh-Cut Lettuce.

    Science.gov (United States)

    Pang, Hao; Lambertini, Elisabetta; Buchanan, Robert L; Schaffner, Donald W; Pradhan, Abani K

    2017-02-01

    Leafy green vegetables, including lettuce, are recognized as potential vehicles for foodborne pathogens such as Escherichia coli O157:H7. Fresh-cut lettuce is potentially at high risk of causing foodborne illnesses, as it is generally consumed without cooking. Quantitative microbial risk assessments (QMRAs) are gaining more attention as an effective tool to assess and control potential risks associated with foodborne pathogens. This study developed a QMRA model for E. coli O157:H7 in fresh-cut lettuce and evaluated the effects of different potential intervention strategies on the reduction of public health risks. The fresh-cut lettuce production and supply chain was modeled from field production, with both irrigation water and soil as initial contamination sources, to consumption at home. The baseline model (with no interventions) predicted a mean probability of 1 illness per 10 million servings and a mean of 2,160 illness cases per year in the United States. All intervention strategies evaluated (chlorine, ultrasound and organic acid, irradiation, bacteriophage, and consumer washing) significantly reduced the estimated mean number of illness cases when compared with the baseline model prediction (from 11.4- to 17.9-fold reduction). Sensitivity analyses indicated that retail and home storage temperature were the most important factors affecting the predicted number of illness cases. The developed QMRA model provided a framework for estimating risk associated with consumption of E. coli O157:H7-contaminated fresh-cut lettuce and can guide the evaluation and development of intervention strategies aimed at reducing such risk.

  3. Impact of mulches and growing season on indicator bacteria survival during lettuce cultivation.

    Science.gov (United States)

    Xu, Aixia; Buchanan, Robert L; Micallef, Shirley A

    2016-05-02

    In fresh produce production, the use of mulches as ground cover to retain moisture and control weeds is a common agricultural practice, but the influence that various mulches have on enteric pathogen survival and dispersal is unknown. The goal of this study was to assess the impact of different mulching methods on the survival of soil and epiphytic fecal indicator bacteria on organically grown lettuce during different growing seasons. Organically managed lettuce, cultivated with various ground covers--polyethylene plastic, corn-based biodegradable plastic, paper and straw mulch--and bare ground as a no-mulch control, was overhead inoculated with manure-contaminated water containing known levels of generic Escherichia coli and Enterococcus spp. Leaves and soil samples were collected at intervals over a two week period on days 0, 1, 3, 5, 7, 10 and 14, and quantitatively assessed for E. coli, fecal coliforms and Enterococcus spp. Data were analyzed using mixed models with repeated measures and an exponential decline with asymptote survival model. Indicator bacterial concentrations in the lettuce phyllosphere decreased over time under all treatments, with more rapid E. coli declines in the fall than in the spring (plettuce compared to mulches. In fall 2014, the E. coli decline rate on paper mulch-grown lettuce was higher (plettuce phyllosphere, and mulch type was a factor for fecal coliform levels (plettuce production may impact the fate of enteric bacteria in soil or on lettuce, most likely in relation to soil moisture retention, and other weather-related factors, such as temperature and rainfall. The data suggest that the time between exposure to a source of enteric bacteria and harvesting of the crop is season dependent, which has implications for determining best harvest times. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Exogenous Glycine Nitrogen Enhances Accumulation of Glycosylated Flavonoids and Antioxidant Activity in Lettuce (Lactuca sativa L.

    Directory of Open Access Journals (Sweden)

    Xiao Yang

    2017-12-01

    Full Text Available Glycine, the simplest amino acid in nature and one of the most abundant free amino acids in soil, is regarded as a model nutrient in organic nitrogen studies. To date, many studies have focused on the uptake, metabolism and distribution of organic nitrogen in plants, but few have investigated the nutritional performance of plants supplied with organic nitrogen. Lettuce (Lactuca sativa L., one of the most widely consumed leafy vegetables worldwide, is a significant source of antioxidants and bioactive compounds such as polyphenols, ascorbic acid and tocopherols. In this study, two lettuce cultivars, Shenxuan 1 and Lollo Rossa, were hydroponically cultured in media containing 4.5, 9, or 18 mM glycine or 9 mM nitrate (control for 4 weeks, and the levels of health-promoting compounds and antioxidant activity of the lettuce leaf extracts were evaluated. Glycine significantly reduced fresh weight compared to control lettuce, while 9 mM glycine significantly increased fresh weight compared to 4.5 or 18 mM glycine. Compared to controls, glycine (18 mM for Shenxuan 1; 9 mM for Lollo Rossa significantly increased the levels of most antioxidants (including total polyphenols, α-tocopherol and antioxidant activity, suggesting appropriate glycine supply promotes antioxidant accumulation and activity. Glycine induced most glycosylated quercetin derivatives and luteolin derivatives detected and decreased some phenolic acids compared to nitrate treatment. This study indicates exogenous glycine supplementation could be used strategically to promote the accumulation of health-promoting compounds and antioxidant activity of hydroponically grown lettuce, which could potentially improve human nutrition.

  5. Exogenous Glycine Nitrogen Enhances Accumulation of Glycosylated Flavonoids and Antioxidant Activity in Lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Yang, Xiao; Cui, Xiaoxian; Zhao, Li; Guo, Doudou; Feng, Lei; Wei, Shiwei; Zhao, Chao; Huang, Danfeng

    2017-01-01

    Glycine, the simplest amino acid in nature and one of the most abundant free amino acids in soil, is regarded as a model nutrient in organic nitrogen studies. To date, many studies have focused on the uptake, metabolism and distribution of organic nitrogen in plants, but few have investigated the nutritional performance of plants supplied with organic nitrogen. Lettuce ( Lactuca sativa L.), one of the most widely consumed leafy vegetables worldwide, is a significant source of antioxidants and bioactive compounds such as polyphenols, ascorbic acid and tocopherols. In this study, two lettuce cultivars, Shenxuan 1 and Lollo Rossa, were hydroponically cultured in media containing 4.5, 9, or 18 mM glycine or 9 mM nitrate (control) for 4 weeks, and the levels of health-promoting compounds and antioxidant activity of the lettuce leaf extracts were evaluated. Glycine significantly reduced fresh weight compared to control lettuce, while 9 mM glycine significantly increased fresh weight compared to 4.5 or 18 mM glycine. Compared to controls, glycine (18 mM for Shenxuan 1; 9 mM for Lollo Rossa) significantly increased the levels of most antioxidants (including total polyphenols, α-tocopherol) and antioxidant activity, suggesting appropriate glycine supply promotes antioxidant accumulation and activity. Glycine induced most glycosylated quercetin derivatives and luteolin derivatives detected and decreased some phenolic acids compared to nitrate treatment. This study indicates exogenous glycine supplementation could be used strategically to promote the accumulation of health-promoting compounds and antioxidant activity of hydroponically grown lettuce, which could potentially improve human nutrition.

  6. Parasitization of commercially available parasitoid species against the lettuce aphid, Nasonovia ribisnigri (Hemiptera: Aphididae).

    Science.gov (United States)

    Shrestha, G; Skovgård, H; Enkegaard, A

    2014-12-01

    The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. Little documentation exists for the control efficacy of aphid parasitoids against N. ribisnigri. This laboratory study evaluated three commercially available parasitoid species: Aphidius colemani (Viereck), Lysiphlebus testaceipes (Cresson), and Aphelinus abdominalis (Dalman) for their mortality impact on N. ribisnigri. The green peach aphid Myzus persicae (Sulzer) was included as a reference aphid. The study showed that A. abdominalis successfully parasitized 39 and 13% of the offered N. ribisnigri and M. persicae, respectively, within a 24-h exposure period. In contrast, none of the lettuce aphids exposed to Ap. colemani or L. testaceipes were successfully parasitized, whereas 60 and 3.5% of M. persicae, respectively, were successfully parasitized within a 6-h exposure period. Lettuce aphid mortality due to incomplete parasitization was 26 and 31% when exposed to Ap. colemani and L. testaceipes, respectively, with corresponding values for M. persicae being 5 and 10%, respectively. Mortality as a result of incomplete parasitization when aphids were exposed to A. abdominalis was low for both aphid species. The total mortality inflicted by A. abdominalis within a 24-h exposure period was 51% for the lettuce aphids and significantly less (19%) for green peach aphids. In contrast, Ap. colemani inflicted a higher mortality in M. persicae (65%) compared with N. ribisnigri (26%) within a 6-h exposure period. L. testaceipes caused a greater mortality in N. ribisnigri as compared with M. persicae. This study concludes that A. abdominalis has the potential to be used against N. ribisnigri in inoculative biocontrol programs as compared with the other parasitoid species based on successful parasitization.

  7. SSH reveals a linkage between a senescence-associated protease and Verticillium wilt symptom development in lettuce (Lactuca sativa)

    Science.gov (United States)

    Suppression subtractive hybridization (SSH) was employed to identify lettuce (Lactuca sativa) genes that are differentially expressed in symptomatic leaves infected with Verticillium dahliae. Genes expressed only in symptomatic leaves included those with homology to pathogenesis-related (PR) protei...

  8. Effects of Minthostachys mollis essential oil and volatiles on seedlings of lettuce, tomato, cucumbre and Bidens pilosa.

    OpenAIRE

    Alonso Amelot, Miguel; Usubillaga, Alfredo; Avila Nuñez, Jorge Luis; Oliveros Bastidas, Alberto; Avendaño Meza, Marisabel

    2007-01-01

    Effects of Minthostachys mollis essential oil and volatiles on seedlings of lettuce, tomato, cucumbre and Bidens pilosa. (Alonso Amelot, Miguel; Usubillaga, Alfredo; Avila Nuñez, Jorge Luis; Oliveros Bastidas, Alberto y Avendaño Meza, Mairsabel) Abstract The extraction and chemical composition of essential oil of Minthostachys mollis (Kunth) Griseb (Lamiaceae) and its inhibitory effects on germation and shoot/root elongation of lettuce, tomato, cucumber and Bidens pilosa (L...

  9. Formation of seed productivity in lettuce Lactuca sativa var. secalina L. depending on the form of inflorescence habitus

    Directory of Open Access Journals (Sweden)

    Н. В. Лещук

    2009-12-01

    Full Text Available It is explained the essence of the formation of seed production of lettuce Lactuca sativa var. secalina L. depending on the form of the inflorescence habitus, which formed during the different areas of plant nutrition. It is substantiated the mechanism of seed formation on different parts of the inflorescence of female plant with identification of it’s sowing quality. It is developed the agrotehnologcal measures aimed at improving the productivity of lettuce seed by overcoming its matrical heteroquality

  10. Economic aspects of the application of different organic materials as N-sources in organic production of lettuce

    OpenAIRE

    Cabilovski, dipl ing Ranko; Manojlovic, Prof Maja; Bogdanovic, Prof Darinka; Bavec, Prof Martina

    2008-01-01

    In a field experiment on a farm registered for organic production, we studied the effect of the application of different organic materials (OM): farmyard manure (FYM), guano (G), soybean seed (S), forage pea seed (P) on lettuce yield. Besides yield, we also analyzed the economic profitability of the application of different OM. Fresh lettuce yield was significantly higher with OM treatments than with the treatments without fertilization. The highest yield was obtained with the FYM treatment (...

  11. Formation of seed productivity in lettuce Lactuca sativa var. secalina L. depending on the form of inflorescence habitus

    OpenAIRE

    Н. В. Лещук

    2009-01-01

    It is explained the essence of the formation of seed production of lettuce Lactuca sativa var. secalina L. depending on the form of the inflorescence habitus, which formed during the different areas of plant nutrition. It is substantiated the mechanism of seed formation on different parts of the inflorescence of female plant with identification of it’s sowing quality. It is developed the agrotehnologcal measures aimed at improving the productivity of lettuce seed by overcoming its matrical he...

  12. Impact of biogas slurry fertilizer on growth, quality and biochemical characteristics of ornamental lettuce 'Biscia Rossa'

    International Nuclear Information System (INIS)

    Jiaxiang, J.; Khalid, M.; Hong, Z.; Leqi, Y.; Dongqin, T.; Danfeng, H.

    2018-01-01

    Biogas slurry is a good source of plant nutrients and substituting chemical fertilizers with biogas slurry not only achieve resource utilization of slurry, but also reduce the amount of fertilizer. The present study investigated the influence of different ratios of biogas slurry fertilizer (BSF) on the growth, yield and quality characteristics of ornamental lettuce 'Biscia Rossa'. Results revealed that BSF significantly (p<0.05) improved the growth of ornamental lettuce on treatment with Z1 fertilizer; the plant height was increased by 12.66% and 16.75%, while leaf area was improved by 19.97% and 42.03%, in comparison with control group. The improvement in yield of ornamental lettuce was noted in varying degrees by BSF. The highest dry and fresh weights were observed in case of Z1 treated lettuce plants. The fresh weight was 33.52%, 44.77%, 43.96% and 49.04% higher than that of other 2 fertilizers and 2 control groups, respectively. Whereas the dry weight was 2.7 and 3.17-times greater than that of two control groups. The biogas slurry irrigation also considerably improved the quality of ornamental lettuce. Moreover, it was observed that vitamin C, anthocyanin, soluble sugar and protein were higher than that of control groups. Contrarily, the BSF led to decrease in nitrate-nitrogen content in ornamental lettuce. (author)

  13. Inflorescence Development and the Role of LsFT in Regulating Bolting in Lettuce (Lactuca sativa L.)

    Science.gov (United States)

    Chen, Zijing; Han, Yingyan; Ning, Kang; Ding, Yunyu; Zhao, Wensheng; Yan, Shuangshuang; Luo, Chen; Jiang, Xiaotang; Ge, Danfeng; Liu, Renyi; Wang, Qian; Zhang, Xiaolan

    2018-01-01

    Lettuce (Lactuca sativa L.) is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT) gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce. PMID:29403510

  14. Inflorescence Development and the Role of LsFT in Regulating Bolting in Lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Chen, Zijing; Han, Yingyan; Ning, Kang; Ding, Yunyu; Zhao, Wensheng; Yan, Shuangshuang; Luo, Chen; Jiang, Xiaotang; Ge, Danfeng; Liu, Renyi; Wang, Qian; Zhang, Xiaolan

    2017-01-01

    Lettuce ( Lactuca sativa L.) is one of the most important leafy vegetable that is consumed during its vegetative growth. The transition from vegetative to reproductive growth is induced by high temperature, which has significant economic effect on lettuce production. However, the progression of floral transition and the molecular regulation of bolting are largely unknown. Here we morphologically characterized the inflorescence development and functionally analyzed the FLOWERING LOCUS T (LsFT) gene during bolting regulation in lettuce. We described the eight developmental stages during floral transition process. The expression of LsFT was negatively correlated with bolting in different lettuce varieties, and was promoted by heat treatment. Overexpression of LsFT could recover the late-flowering phenotype of ft-2 mutant. Knockdown of LsFT by RNA interference dramatically delayed bolting in lettuce, and failed to respond to high temperature. Therefore, this study dissects the process of inflorescence development and characterizes the role of LsFT in bolting regulation in lettuce.

  15. Growth of Three Lettuce Cultivars in NASA's HDU PEM During the 2010 DRATS Test

    Science.gov (United States)

    Stutte, Gary W.; Newsham, Gerard; Wheeler, Raymond

    2011-01-01

    NASA's 2010 Desert Research and Technology Studies (DRATS) of the VEGGIE Food Production System in the Habitat Demonstration Unit (HDU) Pressurized Excursion Module (PEM) was the first operational evaluation of salad crop production technology in a NASA analog test. Rooting media and slow release fertilizers were evaluated for three lettuce cultivars that had shown promise as candidates for a surface based food production system. These tests involved comparing growth, color and quality of the lettuce cultivars grown under VEGGIE LED array (Orbitec, Madison, WI) or Biomass Production System for Education ((BSEe), Orbitec, Madison, WI) compact fluorescent lamps using a gravity feed water delivery system. Mission relevant conditions of CO2, temperature and RH were maintained using controlled environment chambers (EGC, Chagrin Falls, OH). Growth data was obtained for the two red leaf lettuce cultivars, Outredgeous and Firecracker, and the green Bibb lettuce cultivar, Flandria. Growth and quality was evaluated using different concentrations (7.5 g/L and 15 g/L) of commercial slow release fertilizer (Osmocote Plus 15-9-12, Scotts, Maryville, OH) and Nutricote 18-6-8 (Florikan, Sarasota, FL) in either a peat/vermiculite media (sunshine LP5 MiX, Sungro, Bellview, WA) or calcined montmorillonite clay [(arcillite,)Turface Proleague, Profile LLC, Buffalo Grove, IL]. The commercial peat/vermiculite mix generally resulted in larger plants than those grown in arcillite. Increasing the concentration of Osmocote from 7.5 to 15 g/L increased the height, dry mass, and leaf area of lettuce cultivars. In contrast, there was a decrease in growth parameters when concentration of Nutricote was increased from 7.5 to 15 g/L. The best growth was obtained with the 7.5 g/L Nutricote using a commercial peat/vermiculite mixture. This media was used for field testing VEGGIE plant system in the 2010 DRAT test. The VEGGIE nutrient delivery system worked well, was able to be maintained by multiple

  16. Separation of acid blue 25 from aqueous solution using water lettuce and agro-wastes by batch adsorption studies

    Science.gov (United States)

    Kooh, Muhammad Raziq Rahimi; Dahri, Muhammad Khairud; Lim, Linda B. L.; Lim, Lee Hoon; Chan, Chin Mei

    2018-05-01

    Three plant-based materials, namely water lettuce (WL), tarap peel (TP) and cempedak peel (CP), were used to investigate their potentials as adsorbents using acid blue 25 (AB25) dye as a model for acidic dye. The adsorbents were characterised using Fourier transform infrared spectroscopy, X-ray fluorescence and scanning electron microscope. Batch experiments involving parameters such as pH, temperature, contact time, and initial dye concentration were done to investigate the optimal conditions for the adsorption of AB25 onto the adsorbents. Thermodynamics study showed that the uptake of AB25 by the three adsorbents was feasible and endothermic in nature. Both the Langmuir and Freundlich isotherm models can be used to describe the adsorption process of AB25 onto WL and CP while pseudo-second-order fitted the kinetics data, suggesting that chemisorptions were majorly involved. The use of 0.1 M of NaOH showed the best results in regenerating of the WL, TP and CP's adsorption ability after AB25 treatment.

  17. Role of the aphid species and their feeding locations in parasitization behavior of Aphelinus abdominalis, a parasitoid of the lettuce aphid Nasonovia ribisnigri

    OpenAIRE

    Shrestha, Govinda; Skovg?rd, Henrik; Reddy, Gadi V. P.; Steenberg, Tove; Enkegaard, Annie

    2017-01-01

    Aphid species feeding on lettuce occupy distinct feeding sites: the lettuce aphid Nasonovia ribisnigri prefers to feed on heart leaves, whereas the potato aphid Macrosiphum euphorbiae feeds only on outer leaves. The aphid parasitoid Aphelinus abdominalis, known to be able to regulate M. euphorbiae on many crops, has recently been indicated as a promising biocontrol candidate also for use against N. ribisnigri, a major pest of lettuce. This study therefore examined A. abdominalis parasitizatio...

  18. The effect of different physical agents in the behaviour of bss-13 Lettuce variety

    International Nuclear Information System (INIS)

    Perez, C.; Calderon, S.; Mendoza, M.; Perez, M.; Perez, G.; Labrada, A.

    1999-01-01

    The objective of this study was to evaluate and compare the effect of two physical agents in their physiological answer the BSS-13 lettuce variety. Rays gamma Co 60 and rays laser (He-Ne) were the physiological agents utilised. A group of seed were irradiated with gamma in a dose of 10 and 100Grey, and the other group with a time of exposure of 15 sec and 15 min., and power density of 0,4mW/cm2, the rest was no irradiated and was considered like witness. The seed were planted in the protected cultural where remained until of transplantation in field conditions. In the harvest was measured the height, diameter and weight of lettuce. The results show that both agents were presented with an outstanding stimulating with laser with a good efficiency respect to control

  19. Effect of nitrogen and fish manure fertilization on growth and chemical composition of lettuce

    Science.gov (United States)

    Yildirim, Ertan; Kul, Raziye; Turan, Metin; Ekinci, Melek; Alak, Gonca; Atamanalp, Muhammet

    2016-04-01

    Present experiment was designed to determine the response of various dozes of fish manure (FM) and commercial fertilizers on plant growth, yield and nutrient content of lettuce. The treatments consisted of fish manure, commercial fertilizer and the combination of fish manure and commercial fertilizer with four dozes of nitrogen (0 kg/ha, 100 kg/ha, 150 kg/ha and 200 kg/ha). The results of the study showed that treatments significantly affected the growth and chemical characteristics of lettuce. The best results in regard to plant growth and yield were obtained from 100 and 150 kg kg/ha nitrogen dozes of the combination of fish manure and commercial fertilizer.

  20. Lettuce seed germination and root elongation toxicity evaluation of the F-Area seepline soils

    International Nuclear Information System (INIS)

    Nelson, E.A.; Westbury, H.M. Jr.

    1994-09-01

    This study is a continuation of similar studies conducted by Easton and Murphy (1993) and Loehle (1990). The objectives of these studies are to: (1) assess the toxicity of the water-soluble constituents of soil in a seepline adjacent to the F-Area Seepage Basins and (2) evaluate the effectiveness of rainwater movements in reducing the toxicity of the soil. Soils from the F-Area seepline that were found to inhibit lettuce seed germination and radical elongation in 1990 were not found to be significantly different from soils from an uncontaminated control site in this test. After six washings of the soil, the toxicity of the leachate was comparable to that of de-ionized water. This indicates that natural water movements may have rendered the F-Area seepline soils less toxic to lettuce seedlings than in previous tests

  1. Photomorphogenetic responses to UV radiation and short-term red light in lettuce seedlings

    International Nuclear Information System (INIS)

    Kobzar, E.F.; Kreslavski, V.D.; Muzafarov, E.N.

    1998-01-01

    Effects of red light (R), far-red light (FR) and UV radiation on growth and greening of lettuce seedlings (Latuca sativa L., cv. Berlinskii) have been investigated. UV-B and UV-C inhibited hypocotyl elongation and stimulated cotyledonary growth. R in combination with UV-B and UV-C partly eliminated these effects, but FR increased those and reversed the R effect. Chlorophyll accumulation was inhibited by UV-B and UV-C. In comparison with cotyledonary growth, R strengthened the UV inhibitory effect, and FR reversed this effect of R. Thus, UV and phytochrome system modify the effects of each other on hypocotyl and leaf growth in lettuce seedlings depending on the level of active phytochrome formed

  2. Recurring off-types in lettuce: Their significance in plant breeding and seed production.

    Science.gov (United States)

    Maxon Smith, J W

    1977-03-01

    The lettuce cv. Valentine regularly produces non-heading off-type plants at the relatively high frequency of 4 × 10(-3). They result from mutation to the dominant condition. A similar propensity has been reported twice before in lettuce; it is highly heritable.The propensity to produce off-types was not present in the parents of Valentine so it must have arisen during the pedigree breeding programme. Closely related cultivars do not carry the character but it was subsequently transmitted to Dandie a new cultivar of which Valentine was one of the parents. Allelism tests to relate Valentine off-types to those in crisphead cultivars were not successful.The elimination of off-types in breeding programmes is discussed. Contrary to the findings in day-neutral crisphead cultivars, mutant phenotypes in long-day butterhead cultivars have no selective advantage for seed production. Consequently, strict roguing ensures adequate varietal stability.

  3. Interaction effect of phosphorus and boron on yield and quality of lettuce

    Directory of Open Access Journals (Sweden)

    Sultana Zaman Chowdhury

    2015-12-01

    Full Text Available Proper nutrition is essential for satisfactory crop growth and production. A field experiment was conducted at Bangabandhu Sheikh Mujibur Rahman Agricultural University, to evaluate yield and quality of Grand Rapids lettuce using various levels of phosphorus and boron. Treatment combination of 120 kg ha-1 of phosphorus and 2 kg ha-1 of boron has significantly increased plant height, leaf number, leaf length, plant canopy, capsules plant-1, seeds capsule-1, seeds number plant-1, seed yield ha-1, germination (%, planting value (%, moisture (%, purity (%, dry matter (% and 1000 seed weight. Most of the treatment combinations performed better than control treatments in all parameter. The finding could be helpful to determine the precise levels of phosphorus and boron to improve the yield and quality of lettuce.

  4. Effects of vacuum and controlled atmosphere treatments on insect mortality and lettuce quality.

    Science.gov (United States)

    Liu, Yong-Biao

    2003-08-01

    Laboratory studies were conducted to determine the effects of vacuum and controlled atmosphere on mortality of aphids, Nasonovia ribisnigri (Mosley) and Macrosiphum euphorbiae (Thomas), and leafminer, Liriomyza langei Frick, and on the visual quality of iceberg lettuce at three different temperatures. Vacuum at 50 mbar and controlled atmosphere with 6% CO2 were effective in controlling aphids and leafminer larvae. Complete control of N. ribisnigri and M. euphorbiae was achieved with vacuum treatments and 6% CO2 CA treatments at 5 degrees C in 4 d. Mortality was >96% when leafminer larvae were treated with vacuum and 6% CO2 CA treatments for 4 d. However, leafminer pupae were more tolerant to the treatments and highest mortality was close to 60% in 4 d with CO2 under vacuum. None of the treatments had negative effects on visual quality of iceberg lettuce. Results from this study are encouraging and warrant further and large-scale research.

  5. Factors important for the shelf-life of minimally processed lettuce

    DEFF Research Database (Denmark)

    Deza Durand, Karla Michelle

    for a more comprehensive analyses as presented in paper IV. Paper III revealed that packaging and storage time had an influence on the volatiles of cut iceberg lettuce allowing the formation of desirable aroma but also on the development of off-odors. This result indicates that extremely low O2 and high CO2...... significantly higher in passive MAP F1. Regarding the cultivars, Morinas and Diamantinas was the less tolerant to high CO2 resulting in significantly higher amount of 2,3-butanedione. Paper V was related to browning and other physicochemical characteristics of minimally processed lettuce such as soluble sugars...... to influence the formation of browning and other physicochemical characteristics as storage time increased. It was concluded that browning was remarkable controlled in passive MAPs samples, irrespective of season and cultivar due to extremely low O2 and high CO2 conditions, however, after 11 days of storage...

  6. Comparison of Proteome Response to Saline and Zinc Stress in Lettuce

    Directory of Open Access Journals (Sweden)

    Luigi eLucini

    2015-04-01

    Full Text Available Zinc salts occurring in soils can exert an osmotic stress toward plants. However, being zinc a heavy metal, some more specific effects on plant metabolisms can be forecast. In this work, lettuce has been used as a model to investigate salt and zinc stresses at proteome level through a shotgun tandem MS proteomic approach. The effect of zinc stress in lettuce, in comparison with NaCl stress, was evaluated to dissect between osmotic/oxidative stress-related effects, from those changes specifically related to zinc.The analysis of proteins exhibiting a fold change of 3 as minimum (on log 2 normalized abundances, revealed the involvement of photosynthesis (via stimulation of chlorophyll synthesis and enhanced role of photosystem I as well as stimulation of photophosphorylation. Increased glycolytic supply of energy substrates and ammonium assimilation (through formation of glutamine synthetase were also induced by zinc in soil. Similarly, protein metabolism (at both transcriptional and ribosomal level, heat shock proteins and proteolysis were affected. According to their biosynthetic enzymes, hormones appear to be altered by both the treatment and the time point considered: ethylene biosynthesis was enhanced, while production of abscisic acid was up-regulated at the earlier time point to decrease markedly and gibberellins were decreased at the later one.Besides aquaporin PIP2 synthesis, other osmotic/oxidative stress related compounds were enhanced under zinc stress, i.e. proline, hydroxycinnamic acids, ascorbate, sesquiterpene lactones and terpenoids biosynthesis.Although the proteins involved in the response to zinc stress and to salinity were substantially the same, their abundance changed between the two treatments. Lettuce response to zinc was more prominent at the first sampling point, yet showing a faster adaptation than under NaCl stress. Indeed, lettuce plants showed an adaptation after 30 days of stress, in a more pronounced way in the case

  7. Lettuce (Lactuca sativa L. var. Sucrine) growth performance in complemented aquaponic solution outperforms hydroponics

    OpenAIRE

    Delaide, Boris; Goddek, Simon; Gott, James; Soyeurt, Hélène; Jijakli, M.H.

    2016-01-01

    Plant growth performance is optimized under hydroponic conditions. The comparison between aquaponics and hydroponics has attracted considerable attention recently, particularly regarding plant yield. However, previous research has not focused on the potential of using aquaponic solution complemented with mineral elements to commercial hydroponic levels in order to increase yield. For this purpose, lettuce plants were put into AeroFlo installations and exposed to hydroponic (HP), aquaponic (AP...

  8. Physiological responses of seeds and seedlings of lettuce submitted to Philodendron bipinnatifidum extract

    OpenAIRE

    Tiago Zanatta Aumonde; Emanuela Garbin Martinazzo; Tiago Pedó; Junior Borella; Luciano do Amarante; Francisco Amaral Villela; Dario Munt de Moraes

    2013-01-01

    The work was conducted to evaluate the effect of different Philodendron bipinnatifidum Schott. extract concentrations on the physiology and enzymatic metabolism of lettuce seeds and seedlings. The treatments extracts of mature leaves at concentrations of 0, 6, 12, 25 and 50%. Were evaluated the germination, first count germination, speed and germination speed index, length of shoot and primary root, seedling total dry mass, electrical conductivity, chlorophyll content, activity of the enzymes...

  9. Phosphorus levels in soil and lettuce production due to phosphorus fertilization

    Directory of Open Access Journals (Sweden)

    José Ricardo Mantovani

    2014-09-01

    Full Text Available The leafy vegetables are considered nutrient-demanding, but are scarce in the literature works about phosphorus fertilization. This study aimed to evaluate the effect of phosphate on the production of lettuce, content and amount of P accumulated in leaf plants, and to relate levels of P in the clayey soil with plant production. The experiment was conducted in a greenhouse in pots in a randomized block design with ten treatments and four replications. The treatments were made up of P, corresponding to 0, 50, 100, 150, 200, 300, 400, 500, 600 and 700 mg dm-3, as triple superphosphate powder. Portions of 6 dm3 of the clay soil (420 g kg-1 clay received lime, aimed at raising the V % soil to 70 %, equivalent to 20 t ha-1 of cattle manure, and the phosphate fertilizer according to the treatments, remaining incubated for about 30 days. At the end of incubation, each pot received a change of lettuce cultivar Verônica. The plant harvesting was performed 39 days after transplanting the seedlings. O P gave large increases in growth and production of lettuce, and culture responded positively to the application of high doses of the nutrient. A dose of 350 mg dm-3, equivalent to 800 kg ha-1 P2O5, was the most suitable for growing lettuce in the clay soil. In this work conditions, the phosphorus fertilizations it was necessary when the P-Mehlich contents in the clay soil were less than 75 mg dm-3.

  10. IPM for fresh-market lettuce production in the desert southwest: the produce paradox.

    Science.gov (United States)

    Palumbo, John C; Castle, Steven J

    2009-12-01

    In the 'Integrated Control Concept', Stern et al. emphasized that, although insecticides are necessary for agricultural production, they should only be used as a last resort and as a complement to biological control. They argued that selective insecticide use should only be attempted after it has been determined that insect control with naturally occurring biotic agents is not capable of preventing economic damage. However, they concluded their seminal paper by emphasizing that integrated control will not work where natural enemies are inadequate or where economic thresholds are too low to rely on biological control. Thus, it is no surprise that insect control in high-value, fresh-market lettuce crops grown in the desert southwest have relied almost exclusively on insecticides to control a complex of mobile, polyphagous pests. Because lettuce and leafy greens are short-season annual crops with little or no tolerance for insect damage or contamination, biological control is generally considered unacceptable. High expectations from consumers for aesthetically appealing produce free of pesticide residues further forces vegetable growers to use chemical control tactics that are not only effective but safe. Consequently, scientists have been developing integrated pest management (IPM) programs for lettuce that are aimed at reducing the economic, occupational and dietary risks associated with chemical controls of the past. Most of these programs have drawn upon the integrated control concept and promote the importance of understanding the agroecosystem, and the need to sample for pest status and use action thresholds for cost-effective insect control. More recently, pest management programs have implemented newly developed, reduced-risk chemistries that are selectively efficacious against key pests. This paper discusses the influence that the integrated control concept, relative to zero-tolerance market standards and other constraints, has had on the adoption of pest

  11. Uptake of radiocaesium by lettuce crops: the effect of K in soil solution

    International Nuclear Information System (INIS)

    Waegeneers, N.; Camps I Vila, M.; Smolders, E.; Merckx, R.; Sauras, T.; Madoz-Escande, C.

    1998-01-01

    The effect of varying K supply on 137 Cs uptake by lettuce (Lactuca sativa, cv. Batavia, Gloire du Dauphine) was studied in solution culture, in a potted soil experiment and in a greenhouse lysimeter experiment under close-to-real conditions. Lettuce was grown for 13 days in nutrient solution spiked with 137 Cs. Treatments were four concentrations of potassium in solution (25, 50, 250, and 1000 μM). Yields were marginally affected by K supply. The 137 Cs concentration factor (CF, ml/g) decreased 66-fold in the shoot and 432-fold in the roots over the whole K concentration range. The decrease was most pronounced between 25 and 250 μM K. In a subsequent experiment, lettuce was grown for 20 days under the same climatic conditions in two sandy-foam soils (A, B) contaminated with 134 Cs. Both had similar characteristics but differed widely in K supply. Soil solution K concentrations were 100 μM (A) or 3000 μM (B). The radiocesium soil-to-plant Transfer Factor (TF, g plant dry weight / g soil) was 0.320 in soil A and 0.016 in soil B. The higher 137 Cs availability at the lower K supply (soil A) was contrasted by lower 137 Cs concentrations in soil solution of soil A than of soil B. Radiocesium transfer to lettuce grown to maturity was analysed on 5 different lysimeter soils under controlled climatic conditions. The soils were artificially contaminated with 137 Cs in 1994. The TF's varied between 0.032 and 0.191 and were not related to K concentrations in soil solution. The CF decreased about 100-fold with K concentrations increasing from 0.3 to 18 mM. Predictions of soil-to-plant transfer factors based on soil solution composition and nutrient solution results were qualitatively correct but underestimated the observed values

  12. Effete of Gamma Radiation and N.P.K on Lettuce yield

    International Nuclear Information System (INIS)

    Abo Elkhier, O.H.M.M.

    2013-01-01

    Two field experiment were carried out during 2005/2006 winter growing seasons at the experiment at farm of Nuclear Research Center, Atomic Energy Authority, Inshas, Egypt – The experiments were conducted to study the effect of irradiated sowing seeds with 0, 2, 4, 6 and 8 Gray (Gy) of gamma radiation and / or the effect of different levels of NPK fertilizer 0, (NPK)1, (NPK)2, (NPK)3, (NPK)4 and (NPK)5 on the morphological and chemical parameters of the lettuce yield. The fresh weight of the plant in the line, length of the plant in the line, the number of leaves in the line, the number of plants in the line and the fresh weight in Fadden per ton were studied. There were significant effects of NPK contents on the lettuce leaves at (NPK) 4 in the dose level 6 Gy and on Calcium and Vitamins. We found that the most effective doses on leaf lettuce is 6 Gy dose of gamma radiation which gives strong and early seedlings in maturity upwards in the production of seedlings dose of 4 Gy. While the dose 8 Gray did not occur any increase at dose level 6 Gy. The Level (NPK) 4 increase the production of fresh per acre more upwards for all levels with 6 Gray and fourth level was the best in the natural qualities and characteristics of chemical terms of delay growth harvest lettuce, as well as influence on the plant content of calcium, nitrogen, protein and all the natural qualities among the first season and the second season.

  13. Genomic and environmental selection patterns in two distinct lettuce crop-wild hybrid crosses

    OpenAIRE

    Hartman, Y.; Uwimana, B.; Hooftman, D.A.P.; Schranz, M.E.; Wiel, van de, C.C.M.; Smulders, M.J.M.; Visser, R.G.F.; Tienderen, van, P.H.

    2013-01-01

    Genomic selection patterns and hybrid performance influence the chance that crop (trans)genes can spread to wild relatives. We measured fitness(-related) traits in two different field environments employing two different crop?wild crosses of lettuce. We performed quantitative trait loci (QTL) analyses and estimated the fitness distribution of early- and late-generation hybrids. We detected consistent results across field sites and crosses for a fitness QTL at linkage group 7, where a selectiv...

  14. Preventing thermoinhibition in a thermosensitive lettuce genotype by seed imbibition at low temperature

    Directory of Open Access Journals (Sweden)

    Nascimento Warley Marcos

    2003-01-01

    Full Text Available Lettuce (Lactuca sativa L. seed germination is strongly temperature dependent and under high temperatures, germination of most of genotypes can be erratic or completely inhibited. Lettuce seeds of 'Dark Green Boston' (DGB were incubated at temperatures ranging from 15degrees to 35degreesC at light and dark conditions. Other seeds were imbibed in dark at 20degrees; 25degrees; 30degrees; and 35degreesC for 8 and 16 hours and then transferred to 20 or 35degreesC, in dark. Seeds were also incubated at constant temperature of 20degrees and 35 degreesC, in the dark, as control. In another treatment, seeds were primed for 3 days at 15degreesC with constant light. DGB lettuce seeds required light to germinate adequately at temperatures above 25degreesC. Seeds incubated at 20degreesC had 97% germination, whereas seeds incubated at 35degreesC did not germinate. Seeds imbibed at 20degreesC for 8 and 16 hours had germination. At 35degreesC, seeds imbibed initially at 20degreesC for 8 and 16 hours, had 89 and 97% germination, respectively. Seeds imbibed at 25degreesC for 16 hours, germinated satisfactory at 35degreesC. High temperatures of imbibition led to no germination. Primed and non-primed seeds had 100% germination at 20degreesC. Primed seeds had 100% germination at 35degreesC, whereas non-primed seeds germinate only 4%. The first hours of imbibition are very critical for lettuce seed germination at high temperatures.

  15. Exogenous Glycine Nitrogen Enhances Accumulation of Glycosylated Flavonoids and Antioxidant Activity in Lettuce (Lactuca sativa L.)

    OpenAIRE

    Xiao Yang; Xiaoxian Cui; Xiaoxian Cui; Li Zhao; Doudou Guo; Lei Feng; Shiwei Wei; Chao Zhao; Chao Zhao; Danfeng Huang

    2017-01-01

    Glycine, the simplest amino acid in nature and one of the most abundant free amino acids in soil, is regarded as a model nutrient in organic nitrogen studies. To date, many studies have focused on the uptake, metabolism and distribution of organic nitrogen in plants, but few have investigated the nutritional performance of plants supplied with organic nitrogen. Lettuce (Lactuca sativa L.), one of the most widely consumed leafy vegetables worldwide, is a significant source of antioxidants and ...

  16. Elevated CO2 and salinity are responsible for phenolics-enrichment in two differently pigmented lettuces.

    Science.gov (United States)

    Sgherri, Cristina; Pérez-López, Usue; Micaelli, Francesco; Miranda-Apodaca, Jon; Mena-Petite, Amaia; Muñoz-Rueda, Alberto; Quartacci, Mike Frank

    2017-06-01

    Both salt stress and high CO 2 level, besides influencing secondary metabolism, can affect oxidative status of plants mainly acting in an opposite way with salinity provoking oxidative stress and elevated CO 2 alleviating it. The aim of the present work was to study the changes in the composition of phenolic acids and flavonoids as well as in the antioxidant activity in two differently pigmented lettuce cvs (green or red leaf) when submitted to salinity (200 mM NaCl) or elevated CO 2 (700 ppm) or to their combination in order to evaluate how a future global change can affect lettuce quality. Following treatments, the red cv. always maintained higher levels of antioxidant secondary metabolites as well as antioxidant activity, proving to be more responsive to altered environmental conditions than the green one. Overall, these results suggest that the application of moderate salinity or elevated CO 2 , alone or in combination, can induce the production of some phenolics that increase the health benefits of lettuce. In particular, moderate salinity was able to induce the synthesis of the flavonoids quercetin, quercetin-3-O-glucoside, quercetin-3-O-glucuronide and quercitrin. Phenolics-enrichment as well as a higher antioxidant capacity were also observed under high CO 2 with the red lettuce accumulating cyanidin, free chlorogenic acid, conjugated caffeic and ferulic acid as well as quercetin, quercetin-3-O-glucoside, quercetin-3-O-glucuronide, luteolin-7-O-glucoside, rutin, quercitrin and kaempferol. When salinity was present in combination with elevated CO 2 , reduction in yield was prevented and a higher presence of phenolic compounds, in particular luteolin, was observed compared to salinity alone. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  17. The Influence of Thermic Plastic Films on Vegetative and Reproductive Growth of Iceberg Lettuce 'Dublin'

    OpenAIRE

    Wael M. Semida; P. Hadley; W. Sobeih; N. A. El-Sawah; M. A. S. Barakat

    2013-01-01

    Photoselective plastic films with thermic properties are now available so that greenhouses clad with such plastics exhibit a higher degree of “Greenhouse Effect” with a consequent increase in night time temperature. In this study, we investigate the potential benefits of a range of thermic plastic films used as greenhouse cover materials on the vegetative and reproductive growth and development of Iceberg lettuce (Lactuca sativa L). Transplants were grown under thermic fi...

  18. Cadmium Toxicity Affects Phytochemicals and Nutrient Elements Composition of Lettuce (Lactuca sativa L.)

    OpenAIRE

    Jibril, Sani Ahmad; Hassan, Siti Aishah; Ishak, Che Fauziah; Megat Wahab, Puteri Edaroyati

    2017-01-01

    Lettuce varieties Bombilasta BBL and Italian 167 were treated with different concentrations of cadmium (0, 3, 6, 9, and 12 mg/L) in a nutrient film technique (NFT) system to study its toxicity on phytochemicals and nutrient elements. Antioxidants analysis which employed DPPH and FRAP, flavonoids, phenolic, vitamin C, malondialdehyde (MDA), and proline indicated significant effects of Cd treatment on the varieties tested. Different concentration levels of Cd lead to positive interactions in FR...

  19. Transcriptome analysis and anthocyanin-related genes in red leaf lettuce.

    Science.gov (United States)

    Zhang, Y Z; Xu, S Z; Cheng, Y W; Ya, H Y; Han, J M

    2016-01-29

    This study aimed to analyze the transcriptome profile of red lettuce and identify the genes involved in anthocyanin accumulation. Red leaf lettuce is a popular vegetable and popular due to its high anthocyanin content. However, there is limited information available about the genes involved in anthocyanin biosynthesis in this species. In this study, transcriptomes of 15-day-old seedlings and 40-day-old red lettuce leaves were analyzed using an Illuminia HiseqTM 2500 platform. A total of 10.6 GB clean data were obtained and de novo assembled into 83,333 unigenes with an N50 of 1067. After annotation against public databases, 51,850 unigene sequences were identified, among which 46,087 were annotated in the NCBI non-redundant protein database, and 41,752 were annotated in the Swiss-Prot database. A total of 9125 unigenes were mapped into 163 pathways using the Kyoto Encyclopedia of Genes and Genomes database. Thirty-four structural genes were found to cover the main steps of the anthocyanin pathway, including chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, flavonoid 3'-hydroxylase, flavonoid 3',5'-hydroxylase, dihydroflavonol 4-reductase, and anthocyanidin synthase. Seven MYB, three bHLH, and two WD40 genes, considered anthocyanin regulatory genes, were also identified. In addition, 3607 simple sequence repeat (SSR) markers were identified from 2916 unigenes. This research uncovered the transcriptomic characteristics of red leaf lettuce seedlings and mature plants. The identified candidate genes related to anthocyanin biosynthesis and the detected SSRs provide useful tools for future molecular breeding studies.

  20. Elucidating the genetic basis of antioxidant status in lettuce (Lactuca sativa)

    OpenAIRE

    Damerum, Annabelle; Selmes, Stacey L; Biggi, Gaia F; Clarkson, Graham JJ; Rothwell, Steve D; Truco, Maria Jos?; Michelmore, Richard W; Hancock, Robert D; Shellcock, Connie; Chapman, Mark A; Taylor, Gail

    2015-01-01

    A diet rich in phytonutrients from fruit and vegetables has been acknowledged to afford protection against a range of human diseases, but many of the most popular vegetables are low in phytonutrients. Wild relatives of crops may contain allelic variation for genes determining the concentrations of these beneficial phytonutrients, and therefore understanding the genetic basis of this variation is important for breeding efforts to enhance nutritional quality. In this study, lettuce recombinant ...

  1. Effect of the soil type on the microbiome in the rhizosphere of field-grown lettuce

    OpenAIRE

    Schreiter, Susanne; Ding, Guo-Chun; Heuer, Holger; Neumann, Günter; Sandmann, Martin; Grosch, Rita; Kropf, Siegfried; Smalla, Kornelia

    2014-01-01

    The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for 10 years under the same agricultural management to reveal differences directly linked to the soil type and no...

  2. Effect of the soil type on the microbiome in the rhizosphere of field-grown lettuce.

    Science.gov (United States)

    Schreiter, Susanne; Ding, Guo-Chun; Heuer, Holger; Neumann, Günter; Sandmann, Martin; Grosch, Rita; Kropf, Siegfried; Smalla, Kornelia

    2014-01-01

    The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for 10 years under the same agricultural management to reveal differences directly linked to the soil type and not influenced by other factors such as climate or cropping history. Bulk soil and rhizosphere samples were collected 3 and 7 weeks after planting. The analysis of 16S rRNA gene fragments amplified from total community DNA by denaturing gradient gel electrophoresis and pyrosequencing revealed soil type dependent differences in the bacterial community structure of the bulk soils and the corresponding rhizospheres. The rhizosphere effect differed depending on the soil type and the plant growth developmental stage. Despite the soil type dependent differences in the bacterial community composition several genera such as Sphingomonas, Rhizobium, Pseudomonas, and Variovorax were significantly increased in the rhizosphere of lettuce grown in all three soils. The number of rhizosphere responders was highest 3 weeks after planting. Interestingly, in the soil with the highest numbers of responders the highest shoot dry weights were observed. Heatmap analysis revealed that many dominant operational taxonomic units were shared among rhizosphere samples of lettuce grown in diluvial sand, alluvial loam, and loess loam and that only a subset was increased in relative abundance in the rhizosphere compared to the corresponding bulk soil. The findings of the study provide insights into the effect of soil types on the rhizosphere microbiome of lettuce.

  3. Effect of the soil type on the microbiome in the rhizosphere of field-grown lettuce

    Directory of Open Access Journals (Sweden)

    Susanne eSchreiter

    2014-04-01

    Full Text Available The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for ten years under the same agricultural management to reveal differences directly linked to the soil type and not influenced by other factors such as climate or cropping history. Bulk soil and rhizosphere samples were collected three and seven weeks after planting. The analysis of 16S rRNA gene fragments amplified from total community DNA by denaturing gradient gel electrophoresis and pyrosequencing revealed soil type-dependent differences in the bacterial community structure of the bulk soils and the corresponding rhizospheres. The rhizosphere effect differed depending on the soil type and the plant growth developmental stage. Despite the soil type-dependent differences in the bacterial community composition several genera such as Sphingomonas, Rhizobium, Pseudomonas and Variovorax were significantly increased in the rhizosphere of lettuce grown in all three different soils. The number of rhizosphere responders was highest three weeks after planting. Interestingly, in the soil with the highest numbers of responders the highest shoot dry weights were observed. Heatmap analysis revealed that many dominant operational taxonomic units were shared among rhizosphere samples of lettuce grown in diluvial sand, alluvial loam, and loess loam and that only a subset was increased in relative abundance in the rhizosphere compared to the corresponding bulk soil. The findings of the study provide insights into the effect of soil types on the rhizosphere microbiome of lettuce.

  4. Effect of the soil type on the microbiome in the rhizosphere of field-grown lettuce

    OpenAIRE

    Susanne eSchreiter; Susanne eSchreiter; Guo-chun eDing; Guo-chun eDing; Holger eHeuer; Günter eNeumann; Martin eSandmann; Rita eGrosch; Siegfried eKropf; Kornelia eSmalla

    2014-01-01

    The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for ten years under the same agricultural management to reveal differences directly linked to the soil type and n...

  5. Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite.

    Science.gov (United States)

    Bachelli, Mara Lígia Biazotto; Amaral, Rívia Darla Álvares; Benedetti, Benedito Carlos

    2013-01-01

    Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L(-1)/10 min), peracetic acid (100 mg L(-1)/15 min) and ozonated water (1.2 mg L(-1)/1 min) as alternative sanitizers to sodium hypochlorite (150 mg L(-1) free chlorine/15 min) were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 °C with the product packaged on LDPE bags of 60 μm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days.

  6. Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite

    Directory of Open Access Journals (Sweden)

    Mara Lígia Biazotto Bachelli

    2013-09-01

    Full Text Available Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L-1/10 min, peracetic acid (100 mg L-1/15 min and ozonated water (1.2 mg L-1 /1 min as alternative sanitizers to sodium hypochlorite (150 mg L-1 free chlorine/15 min were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 ºC with the product packaged on LDPE bags of 60 µm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days.

  7. Improvement of lettuce seedling vigour after far red irradiation of aged achenes

    International Nuclear Information System (INIS)

    Górski, T.

    1993-01-01

    Far red treatment of aged achenes of lettuce (Lactuca sativa L.) during 4 days after inhibition usually reduced the percentage of seedlings with developmental abnormities. This effect was retained also in redried seeds. The field test yielded a greater number of plants emerging from treated than from control seeds. The results are similar to seed invigoration by other factors inhibiting an immediate germination of imbibed seeds

  8. Evolution of nitrate level in green lettuce conventional grown under natural conditions and aquaponic system

    OpenAIRE

    Flavius Blidariu; Drasovean Alexandru; Grozea Adrian; Radulov Isidora; Lalescu Dacian

    2013-01-01

    Aquaponics integrates growing plants without soil technology with aquaculture, having an important role in recovery of nutrients from effluents. The research aimed to evaluate nitrates level in lettuce (Lactuca sativa) conventional grown under natural conditions and in integrated aquaponic system with a recirculated aquaculture system designed for pikeperch growth (Sander lucioperca). Conventional production (54 plants) has been obtained in the field without fertilizer or pesticide management...

  9. Nutrient Management in Aquaponics: Comparison of Three Approaches for Cultivating Lettuce, Mint and Mushroom Herb

    OpenAIRE

    Valentina Nozzi; Andreas Graber; Zala Schmautz; Alex Mathis; Ranka Junge

    2018-01-01

    Nutrients that are contained in aquaculture effluent may not supply sufficient levels of nutrients for proper plant development and growth in hydroponics; therefore, they need to be supplemented. To determine the required level of supplementation, three identical aquaponic systems (A, B, and C) and one hydroponic system (D) were stocked with lettuce, mint, and mushroom herbs. The aquaponic systems were stocked with Nile tilapia. System A only received nutrients derived from fish feed; system ...

  10. Foliar fertilizations with boron and growth regulators on lettuce (Lactuca sativa L.) cv floresta culture

    International Nuclear Information System (INIS)

    Masunaga, S.I.; Chueire, F.B.; Teixeira, N.T.

    1989-01-01

    The experiment was realized to verify the possibility of applying Boron as foliar fertilization with growth regulators: indol acetic acid, giberellic acid, ethephon and cycocel. The other objective was to compare the foliar and soil fertilization, with Boron, on the lettuce culture. The results showed that there wasn't difference of production between the treatments. Meanwhile the application of growth regulator modified the Boron grade in the leaves. (author) [pt

  11. Development of genomic SSR markers for fingerprinting lettuce (Lactuca sativa L.) cultivars and mapping genes.

    Science.gov (United States)

    Rauscher, Gilda; Simko, Ivan

    2013-01-22

    Lettuce (Lactuca sativa L.) is the major crop from the group of leafy vegetables. Several types of molecular markers were developed that are effectively used in lettuce breeding and genetic studies. However only a very limited number of microsattelite-based markers are publicly available. We have employed the method of enriched microsatellite libraries to develop 97 genomic SSR markers. Testing of newly developed markers on a set of 36 Lactuca accession (33 L. sativa, and one of each L. serriola L., L. saligna L., and L. virosa L.) revealed that both the genetic heterozygosity (UHe = 0.56) and the number of loci per SSR (Na = 5.50) are significantly higher for genomic SSR markers than for previously developed EST-based SSR markers (UHe = 0.32, Na = 3.56). Fifty-four genomic SSR markers were placed on the molecular linkage map of lettuce. Distribution of markers in the genome appeared to be random, with the exception of possible cluster on linkage group 6. Any combination of 32 genomic SSRs was able to distinguish genotypes of all 36 accessions. Fourteen of newly developed SSR markers originate from fragments with high sequence similarity to resistance gene candidates (RGCs) and RGC pseudogenes. Analysis of molecular variance (AMOVA) of L. sativa accessions showed that approximately 3% of genetic diversity was within accessions, 79% among accessions, and 18% among horticultural types. The newly developed genomic SSR markers were added to the pool of previously developed EST-SSRs markers. These two types of SSR-based markers provide useful tools for lettuce cultivar fingerprinting, development of integrated molecular linkage maps, and mapping of genes.

  12. Characteristics of prickly lettuce seed oil in relation to methods of extraction.

    Science.gov (United States)

    Ramadan, A A

    1976-01-01

    Samples of seed oil of prickly lettuce (Lactuca Sacriola oleifera) which had been obtained by pressing or by extracting with acetone, ethyl ether, petroleum ether or carbon tetrachloride were analysed for the following parameters: viscosity, saponification number, iodine number, thiocyanogen value, unsaponifiable matter, free fatty acids, peroxide number and fatty acid composition. The different parameters varied in part considerably in relation to the method of production (pressing or solvent extraction) and to the solvent. It is tried to interprete these relationships.

  13. Impact of Ultraviolet-Blocking Plastic Films on Insect Vectors of Virus Diseases Infesting Crisp Lettuce

    OpenAIRE

    Díaz Desani, Beatriz M.; Biurrun, R.; Moreno, Aránzazu; Nebreda, Miguel; Fereres, Alberto

    2006-01-01

    Ultraviolet (UV)-absorbing plastic films are being used as a photoselective barrier to control insect vectors and associated virus diseases in different horticultural crops. A 2-year experiment was carried out in northeastern Spain (Navarra) to evaluate the impact of a UV-blocking film (AD-IR AV) on the population density of insect pests and the spread of insect-transmitted virus diseases associated with head lettuce [Lactuca sativa (L.)]. Results showed that the UV-absorbing plastic film did...

  14. Dynamics of nonpersistent aphid-borne viruses in lettuce crops covered with UV-absorbing nets.

    Science.gov (United States)

    Legarrea, S; Betancourt, M; Plaza, M; Fraile, A; García-Arenal, F; Fereres, A

    2012-04-01

    Aphid-transmitted viruses frequently cause severe epidemics in lettuce grown under Mediterranean climates. Spatio-temporal dynamics of aphid-transmitted viruses and its vector were studied on lettuce (Lactuca sativa L.) grown under tunnels covered by two types of nets: a commercial UV-absorbing net (Bionet) and a Standard net. A group of plants infected by Cucumber mosaic virus (CMV, family Bromoviridae, genus Cucumovirus) and Lettuce mosaic virus (LMV, family Potyviridae, genus Potyvirus) was transplanted in each plot. The same virus-infected source plants were artificially infested by the aphid Macrosiphum euphorbiae (Thomas). Secondary spread of insects was weekly monitored and plants were sampled for the detection of viruses every two weeks. In 2008, the infection rate of both CMV and LMV were lower under the Bionet than under the Standard cover, probably due to the lower population density and lower dispersal rate achieved by M. euphorbiae. However, during spring of 2009, significant differences in the rate of infection between the two covers were only found for LMV six weeks after transplant. The spatial distribution of the viruses analysed by SADIE methodology was "at random", and it was not associated to the spatial pattern of the vector. The results obtained are discussed analyzing the wide range of interactions that occurred among UV-radiation, host plant, viruses, insect vector and environmental conditions. Our results show that UV-absorbing nets can be recommended as a component of an integrated disease management program to reduce secondary spread of lettuce viruses, although not as a control measure on its own. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Nutrient Management in Aquaponics: Comparison of Three Approaches for Cultivating Lettuce, Mint and Mushroom Herb

    Directory of Open Access Journals (Sweden)

    Valentina Nozzi

    2018-03-01

    Full Text Available Nutrients that are contained in aquaculture effluent may not supply sufficient levels of nutrients for proper plant development and growth in hydroponics; therefore, they need to be supplemented. To determine the required level of supplementation, three identical aquaponic systems (A, B, and C and one hydroponic system (D were stocked with lettuce, mint, and mushroom herbs. The aquaponic systems were stocked with Nile tilapia. System A only received nutrients derived from fish feed; system B received nutrients from fish feed as well as weekly supplements of micronutrients and Fe; system C received the same nutrients as B, with weekly supplements of the macronutrients, P and K; in system D, a hydroponic inorganic solution containing N, Ca, and the same nutrients as system C was added weekly. Lettuce achieved the highest yields in system C, mint in system B, and mushroom herb in systems A and B. The present study demonstrated that the nutritional requirements of the mint and mushroom herb make them suitable for aquaponic farming because they require low levels of supplement addition, and hence little management effort, resulting in minimal cost increases. While the addition of supplements accelerated the lettuce growth (Systems B, C, and even surpassed the growth in hydroponic (System C vs. D, the nutritional quality (polyphenols, nitrate content was better without supplementation.

  16. Lettuce and rhizosphere microbiome responses to growth promoting Pseudomonas species under field conditions.

    Science.gov (United States)

    Cipriano, Matheus A P; Lupatini, Manoeli; Lopes-Santos, Lucilene; da Silva, Márcio J; Roesch, Luiz F W; Destéfano, Suzete A L; Freitas, Sueli S; Kuramae, Eiko E

    2016-12-01

    Plant growth promoting rhizobacteria are well described and recommended for several crops worldwide. However, one of the most common problems in research into them is the difficulty in obtaining reproducible results. Furthermore, few studies have evaluated plant growth promotion and soil microbial community composition resulting from bacterial inoculation under field conditions. Here we evaluated the effect of 54 Pseudomonas strains on lettuce (Lactuca sativa) growth. The 12 most promising strains were phylogenetically and physiologically characterized for plant growth-promoting traits, including phosphate solubilization, hormone production and antagonism to pathogen compounds, and their effect on plant growth under farm field conditions. Additionally, the impact of beneficial strains on the rhizospheric bacterial community was evaluated for inoculated plants. The strains IAC-RBcr4 and IAC-RBru1, with different plant growth promoting traits, improved lettuce plant biomass yields up to 30%. These two strains also impacted rhizosphere bacterial groups including Isosphaera and Pirellula (phylum Planctomycetes) and Acidothermus, Pseudolabrys and Singusphaera (phylum Actinobacteria). This is the first study to demonstrate consistent results for the effects of Pseudomonas strains on lettuce growth promotion for seedlings and plants grown under tropical field conditions. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Changes in spectral signatures of red lettuce regards to Zinc uptake

    Science.gov (United States)

    Shin, J.; Yu, J.; Koh, S. M.; Park, G.; Kim, S.

    2017-12-01

    Heavy metal contaminations caused by human activities such as mining and industrial activities caused serious soil contamination. Soil contaminations causes secondary impact on vegetation by uptake processes. Intakes of vegetables harvested from heavy metal contaminated soil may cause serious health problems. It would be very effective if screening tool could be developed before the vegetables are distributed over the market. This study investigated spectral response of red lettuce regards to Zn uptake from the treated soil in a laboratory condition. Zn solutions at different levels of concentration are injected to potted lettuce. The chemical composition and spectral characteristics of the leaves are analyzed every 2 days and the correlation between the Zn concentration and spectral reflectance is investigated. The experiment reveals that Zn uptake of red lettuce is significantly higher for the leaves from treated pot compared to untreated pot showing highly contaminated concentrations beyond the standard Zn concentrations for food. The spectral response regards to Zn is manifested at certain level of concentration threshold. Below the threshold, reflectance at NIR regions increases regards to increase in Zn concentration. On the other hand, above the threshold, IR reflectance decreases and slope of NIR shoulder increases regards to higher Zn concentration. We think this result may contribute for development of screening tools for heavy metal contaminations in vegetables.

  18. Uptake and Accumulation of Pharmaceuticals in Overhead- and Surface-Irrigated Greenhouse Lettuce.

    Science.gov (United States)

    Bhalsod, Gemini D; Chuang, Ya-Hui; Jeon, Sangho; Gui, Wenjun; Li, Hui; Ryser, Elliot T; Guber, Andrey K; Zhang, Wei

    2018-01-31

    Understanding the uptake and accumulation of pharmaceuticals in vegetables under typical irrigation practices is critical to risk assessment of crop irrigation with reclaimed water. This study investigated the pharmaceutical residues in greenhouse lettuce under overhead and soil-surface irrigations using pharmaceutical-contaminated water. Compared to soil-surface irrigation, overhead irrigation substantially increased the pharmaceutical residues in lettuce shoots. The increased residue levels persisted even after washing for trimethoprim, monensin sodium, and tylosin, indicating their strong sorption to the shoots. The postwashing concentrations in fresh shoots varied from 0.05 ± 0.04 μg/kg for sulfadiazine to 345 ± 139 μg/kg for carbamazepine. Root concentration factors ranged from 0.04 ± 0.14 for tylosin to 19.2 ± 15.7 for sulfamethoxazole. Translocation factors in surface-irrigated lettuce were low for sulfamethoxalzole, trimethoprim, monensin sodium, and tylosin (0.07-0.15), but high for caffeine (4.28 ± 3.01) and carbamazepine (8.15 ± 2.87). Carbamazepine was persistent in soil and hyperaccumulated in shoots.

  19. The morphology, physiology and nutritional quality of lettuce grown under hypobaria and hypoxia

    Science.gov (United States)

    Tang, Yongkang; Gao, Feng; Guo, Shuangsheng; Li, Fang

    2015-07-01

    The objectives of this research were to investigate the morphological, physiological and nutritional characteristics of lettuce plants (Lactuca sativa L. cv. Rome) under hypobaric and hypoxic conditions. Plants were grown under two levels of total pressures (101 and 30 kPa) and three levels of oxygen partial pressures (21, 6 and 2 kPa) for 20 days. Hypoxia (6 or 2 kPa) not only significantly inhibited the growth of lettuce plants by decreasing biomass, leaf area, root/shoot ratio, water content, the contents of minerals and organic compounds (vitamin C, crude protein and crude fat), but also destroyed the ultrastructure of mitochondria and chloroplast. The activities of catalase and total superoxide dismutase, the contents of glutathione and the total antioxidant capacity significantly decreased due to hypoxia. Hypobaria (30 kPa) did not markedly enhance the biomass, but it increased leaf area, root/shoot ratio and relative water content. Hypobaria also decreased the contents of total phenols, malondialdehyde and total carbohydrate and protected the ultrastructure of mitochondria and chloroplast under hypoxia. Furthermore, the activities of catalase and total superoxide dismutase, the contents of minerals and organic compounds markedly increased under hypobaria. This study demonstrates that hypobaria (30 kPa) does not increase the growth of lettuce plants, but it enhances plant's stress resistance and nutritional quality under hypoxia.

  20. The Effect of Plant Growth Promoting Bacteria on Transplants Growth and Lettuce Yield in Organic Production

    Directory of Open Access Journals (Sweden)

    Szczech Magdalena

    2016-12-01

    Full Text Available Application of beneficial bacterial strain B125 (Enterobacter sp. and strain PZ9 (Bacillus sp. in lettuce transplants production significantly enhanced seed germination and plant biomass. The best effect was obtained when the mixture of B125 and PZ9 was used. Combined application of these bacteria significantly increased transplants biomass, which was about 45% higher than that in the control. However, after planting these transplants in organic field, generally, there were no differences in yield and nutrient content in plants treated and not treated with the bacteria, except for nitrogen and vitamin C. The lettuce grown from transplants treated with bacterial mixture B125 + PZ9 contained significantly higher nitrogen than plants from other treatments. Opposite to nitrogen, bacterial applications decreased the amount of vitamin C. The growth and organic lettuce composition was affected by planting time. The yield was higher in spring, but the concentration of nutrients in these plants was lower than that in plants harvested in autumn. Climatic and light conditions in the late season were the reasons for increased dry matter content, minerals, phenolic compounds, and vitamin C, as well as high concentration of nitrates.

  1. Improving “color rendering” of LED lighting for the growth of lettuce

    Science.gov (United States)

    Han, Tao; Vaganov, Vitaliy; Cao, Shixiu; Li, Qiang; Ling, Lili; Cheng, Xiaoyao; Peng, Lingling; Zhang, Congzhi; Yakovlev, Alexey N.; Zhong, Yang; Tu, Mingjing

    2017-04-01

    Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve “color rendering” of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 μmol·m-2·s-1 for a 16 hd-1 photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were investigated. We let the absorption spectrum of fresh leaf be the emission spectrum of ideal light and then evaluate the “color rendering” of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates. Under the irradiation of red-yellow-blue light with high correlation coefficient of 0.587, the dry weights and leaf growth rate are 2-3 times as high as the sharp red-blue light. The optimized LED light for lettuce growth can be presumed to be limited to the angle (about 75°) between the vectors passed through the ideal light in the CIE chromaticity coordinates. These findings open up a new idea to assess and find the optimized LED light for plant growth.

  2. Agricultural and Management Practices and Bacterial Contamination in Greenhouse versus Open Field Lettuce Production

    Science.gov (United States)

    Holvoet, Kevin; Sampers, Imca; Seynnaeve, Marleen; Jacxsens, Liesbeth; Uyttendaele, Mieke

    2014-01-01

    The aim of this study was to gain insight into potential differences in risk factors for microbial contamination in greenhouse versus open field lettuce production. Information was collected on sources, testing, and monitoring and if applicable, treatment of irrigation and harvest rinsing water. These data were combined with results of analysis on the levels of Escherichia coli as a fecal indicator organism and the presence of enteric bacterial pathogens on both lettuce crops and environmental samples. Enterohemorragic Escherichia coli (EHEC) PCR signals (vt1 or vt2 positive and eae positive), Campylobacter spp., and Salmonella spp. isolates were more often obtained from irrigation water sampled from open field farms (21/45, 46.7%) versus from greenhouse production (9/75, 12.0%). The open field production was shown to be more prone to fecal contamination as the number of lettuce samples and irrigation water with elevated E. coli was significantly higher. Farmers comply with generic guidelines on good agricultural practices available at the national level, but monitoring of microbial quality, and if applicable appropriateness of water treatment, or water used for irrigation or at harvest is restricted. These results indicate the need for further elaboration of specific guidelines and control measures for leafy greens with regard to microbial hazards. PMID:25546272

  3. An unusual spliced variant of DELLA protein, a negative regulator of gibberellin signaling, in lettuce.

    Science.gov (United States)

    Sawada, Yoshiaki; Umetsu, Asami; Komatsu, Yuki; Kitamura, Jun; Suzuki, Hiroyuki; Asami, Tadao; Fukuda, Machiko; Honda, Ichiro; Mitsuhashi, Wataru; Nakajima, Masatoshi; Toyomasu, Tomonobu

    2012-01-01

    DELLA proteins are negative regulators of the signaling of gibberellin (GA), a phytohormone regulating plant growth. DELLA degradation is triggered by its interaction with GID1, a soluble GA receptor, in the presence of bioactive GA. We isolated cDNA from a spliced variant of LsDELLA1 mRNA in lettuce, and named it LsDELLA1sv. It was deduced that LsDELLA1sv encodes truncated LsDELLA1, which has DELLA and VHYNP motifs at the N terminus but lacks part of the C-terminal GRAS domain. The recombinant LsDELLA1sv protein interacted with both Arabidopsis GID1 and lettuce GID1s in the presence of GA. A yeast two-hybrid assay suggested that LsDELLA1sv interacted with LsDELLA1. The ratio of LsDELLA1sv to LsDELLA1 transcripts was higher in flower samples at the late reproductive stage and seed samples (dry seeds and imbibed seeds) than in the other organ samples examined. This study suggests that LsDELLA1sv is a possible modulator of GA signaling in lettuce.

  4. Hybridization rates between lettuce (Lactuca sativa) and its wild relative (L. serriola) under field conditions.

    Science.gov (United States)

    D'Andrea, Luigi; Felber, François; Guadagnuolo, Roberto

    2008-01-01

    Hybridization and introgression between crops and wild relatives may have important evolutionary and ecological consequences such as gene swamping or increased invasiveness. In the present study, we investigated hybridization under field conditions between crop lettuce (Lactuca sativa) and its wild relative prickly lettuce (L. serriola), two cross-compatible, predominantly autogamous and insect pollinated species. In 2003 and 2004, we estimated the rates of hybridization between L. sativa and L. serriola in close-to-reality field experiments carried out in two locations of Northern Switzerland. Seeds set by the experimental wild plants were collected and sown (44 352 in 2003 and 252 345 in 2004). Progeny was screened morphologically for detecting natural hybrids. Prior to the experiment, specific RAPD markers were used to confirm that morphological characters were reliable for hybrid identification. Hybridization occurred up to the maximal distance tested (40 m), and hybridization rates varied between 0 to 26%, decreasing with distance. More than 80% of the wild plants produced at least one hybrid (incidence of hybridization, IH) at 0 m and 1 m. It equaled 4 to 5% at 40 m. In sympatric crop-wild populations, cross-pollination between cultivated lettuce and its wild relative has to be seen as the rule rather than the exception for short distances.

  5. An Ultra-High-Density, Transcript-Based, Genetic Map of Lettuce

    Science.gov (United States)

    Truco, Maria José; Ashrafi, Hamid; Kozik, Alexander; van Leeuwen, Hans; Bowers, John; Wo, Sebastian Reyes Chin; Stoffel, Kevin; Xu, Huaqin; Hill, Theresa; Van Deynze, Allen; Michelmore, Richard W.

    2013-01-01

    We have generated an ultra-high-density genetic map for lettuce, an economically important member of the Compositae, consisting of 12,842 unigenes (13,943 markers) mapped in 3696 genetic bins distributed over nine chromosomal linkage groups. Genomic DNA was hybridized to a custom Affymetrix oligonucleotide array containing 6.4 million features representing 35,628 unigenes of Lactuca spp. Segregation of single-position polymorphisms was analyzed using 213 F7:8 recombinant inbred lines that had been generated by crossing cultivated Lactuca sativa cv. Salinas and L. serriola acc. US96UC23, the wild progenitor species of L. sativa. The high level of replication of each allele in the recombinant inbred lines was exploited to identify single-position polymorphisms that were assigned to parental haplotypes. Marker information has been made available using GBrowse to facilitate access to the map. This map has been anchored to the previously published integrated map of lettuce providing candidate genes for multiple phenotypes. The high density of markers achieved in this ultradense map allowed syntenic studies between lettuce and Vitis vinifera as well as other plant species. PMID:23550116

  6. An Ultra-High-Density, Transcript-Based, Genetic Map of Lettuce.

    Science.gov (United States)

    Truco, Maria José; Ashrafi, Hamid; Kozik, Alexander; van Leeuwen, Hans; Bowers, John; Wo, Sebastian Reyes Chin; Stoffel, Kevin; Xu, Huaqin; Hill, Theresa; Van Deynze, Allen; Michelmore, Richard W

    2013-04-09

    We have generated an ultra-high-density genetic map for lettuce, an economically important member of the Compositae, consisting of 12,842 unigenes (13,943 markers) mapped in 3696 genetic bins distributed over nine chromosomal linkage groups. Genomic DNA was hybridized to a custom Affymetrix oligonucleotide array containing 6.4 million features representing 35,628 unigenes of Lactuca spp. Segregation of single-position polymorphisms was analyzed using 213 F 7:8 recombinant inbred lines that had been generated by crossing cultivated Lactuca sativa cv. Salinas and L. serriola acc. US96UC23, the wild progenitor species of L. sativa The high level of replication of each allele in the recombinant inbred lines was exploited to identify single-position polymorphisms that were assigned to parental haplotypes. Marker information has been made available using GBrowse to facilitate access to the map. This map has been anchored to the previously published integrated map of lettuce providing candidate genes for multiple phenotypes. The high density of markers achieved in this ultradense map allowed syntenic studies between lettuce and Vitis vinifera as well as other plant species. Copyright © 2013 Truco et al.

  7. Positive effects of temperature and growth conditions on enzymatic and antioxidant status in lettuce plants.

    Science.gov (United States)

    Boo, Hee-Ock; Heo, Buk-Gu; Gorinstein, Shela; Chon, Sang-Uk

    2011-10-01

    The contents of two bioactive compounds (polyphenols and flavonoids) and their antioxidant and enzyme activities were determined in the leaves of six lettuce (Latuca sativa L.) cultivars subjected to 4 different day/night temperatures for 6 weeks. The total polyphenol and anthocyanin contents and the corresponding antioxidant activities were the highest at 13/10°C and 20/13°C, followed by 25/20°C and 30/25°C. The enzymatic activities of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) were also the highest at low day/night temperatures, but the peroxidase (POD) activity was decreased at low day/night temperatures and increased at high day/night temperatures. The most significant positive correlation existed between anthocyanin content and PPO activity, total polyphenols and their antioxidant activities. The results showed that at relatively low temperatures, lettuce plants have a high antioxidant and enzymatic status. These results provide additional information for the lettuce growers. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  8. Diversity and evolutionary history of lettuce necrotic yellows virus in Australia and New Zealand.

    Science.gov (United States)

    Higgins, Colleen M; Chang, Wee-Leong; Khan, Subuhi; Tang, Joe; Elliott, Carol; Dietzgen, Ralf G

    2016-02-01

    Lettuce necrotic yellows virus (LNYV) is the type member of the genus Cytorhabdovirus, family Rhabdoviridae, and causes a severe disease of lettuce (Lactuca sativa L.). This virus has been described as endemic to Australia and New Zealand, with sporadic reports of a similar virus in Europe. Genetic variability studies of plant-infecting rhabdoviruses are scarce. We have extended a previous study on the variability of the LNYV nucleocapsid gene, comparing sequences from isolates sampled from both Australia and New Zealand, as well as analysing symptom expression on Nicotiana glutinosa. Phylogenetic and BEAST analyses confirm separation of LNYV isolates into two subgroups (I and II) and suggest that subgroup I is slightly older than subgroup II. No correlation was observed between isolate subgroup and disease symptoms on N. glutinosa. The origin of LNYV remains unclear; LNYV may have moved between native and weed hosts within Australia or New Zealand before infecting lettuce or may have appeared as a result of at least two incursions, with the first coinciding with the beginning of European agriculture in the region. The apparent extinction of subgroup I in Australia may have been due to less-efficient dispersal than that which has occurred for subgroup II - possibly a consequence of suboptimal interactions with plant and/or insect hosts. Introduction of subgroup II to New Zealand appears to be more recent. More-detailed epidemiological studies using molecular tools are needed to fully understand how LNYV interacts with its hosts and to determine where the virus originated.

  9. Allelopathic activity of medicinal plant essential oils on seed germination and vigor of lettuce achenes

    Directory of Open Access Journals (Sweden)

    Cíntia Alvarenga Santos Fraga de Miranda

    2015-07-01

    Full Text Available In recent years, essential oils have gained commercial interest in the agricultural area, mainly for their allelopathic, insecticidal, antifungal, antimicrobial and antioxidant properties, and, also for their natural compounds, which have generally displayed low toxicity, relatively low cost and rapid degradation in the environment. Medicinal plants have emerged as potential suppliers of essential oils because of their ethnopharmacological utility. The aim of this study was to evaluate the allelopathic potential of essential oils extracted from fresh leaves of lemon grass (Cymbopogon citratus, wild basil (Ocimum gratissimum L. and sweet basil (Ocimum basilicum L. with regard to their major constituents (citral, eugenol and cineol, respectively in different application forms (direct contact and the effect of volatile constituents on the germination and vigor of lettuce seeds (cultivar Regina SF 3500. The effects of the oils and their major components were evaluated with regard to the variables: first germination count, total germination, GVI (germination velocity index, seedling dry weight and average lengths of shoots and lettuce roots. The essential oils from lemon grass and basil displayed allelopathic potentials on seed germination and vigor of lettuce achenes that can be assigned to their respective major constituents citral and eugenol. On the other hand, the allelopathic effect of the essential oil from basil was a consequence of the combined effect of all the components, regardless the application method.

  10. Nutritional disorder of lettuce cv. Veronica in nutrient solution with suppressed macronutrients

    Directory of Open Access Journals (Sweden)

    Thiago Batista Firmato de Almeida

    2011-06-01

    Full Text Available Lettuce is the most popular of the leafy vegetables. It is known worldwide and its consumption occurs mainly in the natural form. The objective was to evaluate the effect of macronutrient omission on the growth and nutritional status of the lettuce cv. Veronica, and to describe the visual symptoms of nutritional deficiency. The treatments complete consisted of the solution and the individual omission of N, P, K, Ca, Mg and S, under a completely randomized design with three replications. Plants were grown in Hoagland & Arnon, in pots (8L. At 56 days after transplant we evaluated plant height, leaf number, leaf area, SPAD index, dry matter of shoots, roots and whole plant, levels of macronutrients in shoots and roots, and the nature of nutritional disorders. The omission of nutrients affected the growth variables. The nutrients found in lettuce plants from nutrient solution and the complete omission in the shoot were, respectively, N= 23.2 to 9.5, P= 5.4 to 1.3, K= 58,9 to 3.2, Ca= 12.1 to 3.6, Mg= 5.5 to 0.7 and S= 3.2 to 1.5g.kg-1. The omission of macronutrients caused quality losses, since it affected the nutrition of the vegetables and this resulted in morphological changes, reflected as symptoms of deficiency for each nutrient.

  11. Variability, plot size and border effect in lettuce trials in protected environment

    Directory of Open Access Journals (Sweden)

    Daniel Santos

    2018-03-01

    Full Text Available ABSTRACT The variability within rows of cultivation may reduce the accuracy of experiments conducted in a complete randomized block design if the rows are considered as blocks, however, little is known about this variability in protected environments. Thus, our aim was to study the variability of the fresh mass in lettuce shoot, growing in protected environment, and to verify the border effect and size of the experimental unit in minimizing the productive variability. Data from two uniformity trials carried out in a greenhouse in autumn and spring growing seasons were used. In the statistical analyses, it was considered the existence of parallel cultivation rows the lateral openings of the greenhouse and of columns perpendicular to these openings. Different scenarios were simulated by excluding rows and columns to generate several borders arrangements and also to use different sizes of the experimental unit. For each scenario, homogeneity test of variances between remaining rows and columns was performed, and it was calculated the variance and coefficient of variation. There is variability among rows in trials with lettuce in plastic greenhouses and the border use does not bring benefits in terms of reduction of the coefficient of variation or minimizing the cases of heterogeneous variances among rows. In experiments with lettuce in a plastic greenhouse, the use of an experimental unit size greater than or equal to two plants provides homogeneity of variances among rows and columns and, therefore, allows the use of a completely randomized design.

  12. Composition of hydroponic lettuce: effect of time of day, plant size, and season.

    Science.gov (United States)

    Gent, Martin P N

    2012-02-01

    The diurnal variation of nitrate and sugars in leafy green vegetables may vary with plant size or the ability of plants to buffer the uptake, synthesis, and use of metabolites. Bibb lettuce was grown in hydroponics in a greenhouse and sampled at 3 h intervals throughout one day in August 2007 and another day in November 2008 to determine fresh weight, dry matter, and concentration of nitrate and sugars. Plantings differing in size and age were sampled on each date. The dry/fresh weight ratio increased during the daylight period. This increase was greater for small compared to large plants. On a fresh weight basis, tissue nitrate of small plants was only half that of larger plants. The variation in concentration with time was much less for nitrate than for soluble sugars. Soluble sugars were similar for all plant sizes early in the day, but they increased far more for small compared to large plants in the long days of summer. The greatest yield on a fresh weight basis was obtained by harvesting lettuce at dawn. Although dry matter or sugar content increased later in the day, there is no commercial benefit to delaying harvest as consumers do not buy lettuce for these attributes. Copyright © 2011 Society of Chemical Industry.

  13. Nitrogen utilization and environmental losses in organic greenhouse lettuce amended with two distinct biochars.

    Science.gov (United States)

    Pereira, Engil Isadora Pujol; Conz, Rafaela Feola; Six, Johan

    2017-11-15

    The potential of biochar to prevent nitrogen (N) losses and improve plant performance were studied across various levels of N input for two growing seasons in mesocosms simulating an organic lettuce production system. A silt loam soil was amended with pine chip (PC) and walnut shell (WS) biochar (10tha -1 ) in combination with five organic N fertilization rates (0, 56, 112, 168, and 225kgNha -1 ). The N output through harvest, leachate, and N 2 O emissions were measured to assess N utilization and environmental losses of biochar-amended soils. For both biochars, only at the 100% N fertilization rate was lettuce biomass production improved with significant increases in N use efficiency (NUE); however, only PC biochar decreased N losses via leaching (at 100% N fertilization rate) and seasonal N 2 O emissions (at 50% N fertilization rate). Thus, due to increases in plant biomass and decreases in N losses, PC biochar significantly decreased the ratio of N lost over N exported in biomass. Findings from this study suggest that both WS and PC biochars can improve organic lettuce production but only at 225kgNha -1 . Decreases in N losses via leachate and N 2 O emissions vary with fertilization level and biochar type. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Semi-High Throughput Screening for Potential Drought-tolerance in Lettuce (Lactuca sativa) Germplasm Collections.

    Science.gov (United States)

    Knepper, Caleb; Mou, Beiquan

    2015-04-17

    This protocol describes a method by which a large collection of the leafy green vegetable lettuce (Lactuca sativa L.) germplasm was screened for likely drought-tolerance traits. Fresh water availability for agricultural use is a growing concern across the United States as well as many regions of the world. Short-term drought events along with regulatory intervention in the regulation of water availability coupled with the looming threat of long-term climate shifts that may lead to reduced precipitation in many important agricultural regions has increased the need to hasten the development of crops adapted for improved water use efficiency in order to maintain or expand production in the coming years. This protocol is not meant as a step-by-step guide to identifying at either the physiological or molecular level drought-tolerance traits in lettuce, but rather is a method developed and refined through the screening of thousands of different lettuce varieties. The nature of this screen is based in part on the streamlined measurements focusing on only three water-stress indicators: leaf relative water content, wilt, and differential plant growth following drought-stress. The purpose of rapidly screening a large germplasm collection is to narrow the candidate pool to a point in which more intensive physiological, molecular, and genetic methods can be applied to identify specific drought-tolerant traits in either the lab or field. Candidates can also be directly incorporated into breeding programs as a source of drought-tolerance traits.

  15. The effect of competition from neighbours on stomatal conductance in lettuce and tomato plants.

    Science.gov (United States)

    Vysotskaya, Lidiya; Wilkinson, Sally; Davies, William J; Arkhipova, Tatyana; Kudoyarova, Guzel

    2011-05-01

    Competition decreased transpiration from young lettuce plants after 2 days, before any reductions in leaf area became apparent, and stomatal conductance (g(s) ) of lettuce and tomato plants was also reduced. Stomatal closure was not due to hydraulic signals or competition for nutrients, as soil water content, leaf water status and leaf nitrate concentrations were unaffected by neighbours. Competition-induced stomatal closure was absent in an abscisic acid (ABA)-deficient tomato mutant, flacca, indicating a fundamental involvement of ABA. Although tomato xylem sap ABA concentrations were unaffected by the presence of neighbours, ABA/pH-based stomatal modulation is still likely to underlie the response to competition, as soil and xylem sap alkalization was observed in competing plants. Competition also modulated leaf ethylene production, and treatment of lettuce plants with an ethylene perception inhibitor (1-methylcyclopropene) diminished the difference in g(s) between single and competing plants grown in a controlled environment room, but increased it in plants grown in the greenhouse: ethylene altered the extent of the stomatal response to competition. Effects of competition on g(s) are discussed in terms of the detection of the absence of neighbours: increases in g(s) and carbon fixation may allow faster initial space occupancy within an emerging community/crop. © 2011 Blackwell Publishing Ltd.

  16. Understanding trophic interactions of Orius spp. (Hemiptera: Anthocoridae) in lettuce crops by molecular methods.

    Science.gov (United States)

    Gomez-Polo, Priscila; Alomar, Oscar; Castañé, Cristina; Aznar-Fernández, Thaïs; Lundgren, Jonathan G; Piñol, Josep; Agustí, Nuria

    2016-02-01

    The aphid Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae) and the thrips Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) are common pests in Mediterranean lettuce crops, where Orius spp. are common generalist predators. Predation by Orius spp. was studied in a lettuce plot by conventional polymerase chain reaction (PCR) and real-time PCR analyses using specific primers of both main pests. Also, high-throughput sequencing was used to have a wider approach of the diet of these predators in natural field conditions. Molecular analyses indicated a higher predation on N. ribisnigri in spring and on F. occidentalis in summer. Predation on alternative prey, like Collembola, was also found in both seasons. Real-time PCR was more sensitive than conventional PCR in showing the target trophic links, whereas high-throughput sequencing revealed predation on other natural enemies - intraguild predation (IGP), showing other trophic interactions of Orius majusculus within the studied ecosystem. This study gives important information about the trophic relationships present in Mediterranean lettuce crops in different periods of the year. The detected predation by Orius spp. on alternative prey, as well as on other natural enemies, should be further investigated to clarify whether it adds or detracts to the biological control of N. ribisnigri and F. occidentalis. © 2015 Society of Chemical Industry.

  17. Uptake of azoles by lamb's lettuce (Valerianella locusta L.) grown in hydroponic conditions.

    Science.gov (United States)

    García-Valcárcel, Ana I; Loureiro, Iñigo; Escorial, Concepción; Molero, Encarnación; Tadeo, José L

    2016-02-01

    An uptake and translocation study of azole compounds was performed in lamb's lettuce (Valerianella locusta L.) grown in nutrient solution fortified with different azoles. Three azoles, (clotrimazole, fluconazole and propiconazole), which have different physico-chemical properties and are ubiquitous in the aquatic environment, were the compounds selected. An analytical method, based on matrix solid phase dispersion (MSPD) followed by LC-MS/MS determination, was developed to quantify these compounds in aqueous solution and in roots and leaves. The physicochemical properties of azoles are the main factors governing the uptake and plant accumulation. These azoles were detected in leaves indicating their transport within lamb's lettuce. Translocation from nutrient solution to the aerial part of lamb's lettuce was found to be highly dependent on the hydrophobicity of the azole. Clotrimazole accumulates in roots causing necrosis in roots and leaves, whereas fluconazole was the azole with the highest concentration in leaves without causing apparent phytotoxicity symptoms. The assessment of the levels of these azoles in leaves indicates that the risk for human health is negligible. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Effect of biochar amendment on the control of soil sulfonamides, antibiotic-resistant bacteria, and gene enrichment in lettuce tissues

    International Nuclear Information System (INIS)

    Ye, Mao; Sun, Mingming; Feng, Yanfang; Wan, Jinzhong; Xie, Shanni; Tian, Da; Zhao, Yu; Wu, Jun; Hu, Feng; Li, Huixin; Jiang, Xin

    2016-01-01

    Highlights: • Biochar can prevent soil sulfonamides from accumulating in lettuce tissues. • ARB enrichment in lettuce tissues decreased significantly after biochar amendment. • Impedance effect of biochar addition on soil ARGs was also quite effective. • Biochar application can be a practical strategy to protect vegetable safety. - Abstract: Considering the potential threat of vegetables growing in antibiotic-polluted soil with high abundance of antibiotic-resistant genes (ARGs) against human health through the food chain, it is thus urgent to develop novel control technology to ensure vegetable safety. In the present work, pot experiments were conducted in lettuce cultivation to assess the impedance effect of biochar amendment on soil sulfonamides (SAs), antibiotic-resistant bacteria (ARB), and ARG enrichment in lettuce tissues. After 100 days of cultivation, lettuce cultivation with biochar amendment exhibited the greatest soil SA dissipation as well as the significant improvement of lettuce growth indices, with residual soil SAs mainly existing as the tightly bound fraction. Moreover, the SA contents in roots and new/old leaves were reduced by one to two orders of magnitude compared to those without biochar amendment. In addition, isolate counts for SA-resistant bacterial endophytes in old leaves and sul gene abundances in roots and old leaves also decreased significantly after biochar application. However, neither SA resistant bacteria nor sul genes were detected in new leaves. It was the first study to demonstrate that biochar amendment can be a practical strategy to protect lettuce safety growing in SA-polluted soil with rich ARB and ARGs.

  19. Escherichia coli transfer from simulated wildlife feces to lettuce during foliar irrigation: A field study in the Northeastern United States.

    Science.gov (United States)

    Weller, Daniel L; Kovac, Jasna; Kent, David J; Roof, Sherry; Tokman, Jeffrey I; Mudrak, Erika; Kowalcyk, Barbara; Oryang, David; Aceituno, Anna; Wiedmann, Martin

    2017-12-01

    Wildlife intrusion has been associated with pathogen contamination of produce. However, few studies have examined pathogen transfer from wildlife feces to pre-harvest produce. This study was performed to calculate transfer coefficients for Escherichia coli from simulated wildlife feces to field-grown lettuce during irrigation. Rabbit feces inoculated with a 3-strain cocktail of non-pathogenic E. coli were placed in a lettuce field 2.5-72 h before irrigation. Following irrigation, the E. coli concentration on the lettuce was determined. After exclusion of an outlier with high E. coli levels (Most Probable Number = 5.94*10 8 ), the average percent of E. coli in the feces that transferred to intact lettuce heads was 0.0267% (Standard Error [SE] = 0.0172). Log-linear regression showed that significantly more E. coli transferred to outer leaves compared to inner leaves (Effect = 1.3; 95% Confidence Interval = 0.4, 2.1). Additionally, the percent of E. coli that transferred from the feces to the lettuce decreased significantly with time after fecal placement, and as the distance between the lettuce and the feces, and the lettuce and the sprinklers increased. These findings provide key data that may be used in future quantitative risk assessments to identify potential intervention strategies for reducing food safety risks associated with fresh produce. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Biodegradable films of starch/PVOH/alginate in packaging systems for minimally processed lettuce (Lactuca sativa L.

    Directory of Open Access Journals (Sweden)

    Renata Paula Herrera Brandelero

    Full Text Available ABSTRACT Biodegradable packaging may replace non-biodegradable materials when the shelf life of the packaged product is relatively short, as in minimally processed foods. The objective of this work was to evaluate the efficiency of biodegradable films comprising starch/polyvinyl alcohol (PVOH/alginate with the addition of 0 or 0.5% of essential oil of copaiba (EOCP or lemongrass (EOLM compared to poly-vinyl chloride (PVC films in the storage of minimally processed lettuce. Lettuce samples cut into 1-cm strips were placed in polypropylene trays wrapped with biodegradable films and stored at 6 ± 2 °C for 8 days. PVC films were used as controls. The biofilms presented 11.43-8.11 MPa resistance and 11.3-13.22% elongation, with water vapor permeability (WVP of 0.5-4.04 x 10-12 g. s-1.Pa-1.m-1; thus, the films' properties were considered suitable for the application. The lettuce stored in PVC presented minor total soluble solids (TSS, less luminosity (L, higher intensity of yellow color (b, and eight times less mass loss than that stored in biodegradable films. Multivariate analysis showed that the lettuce lost quality after 2 days of storage in PVC films, representing a different result from the other treatments. Lettuce stored in biodegradable films for 2 and 4 days showed a greater similarity with newly harvested lettuce (time zero. The films with or without the addition of essential oil showed similar characteristics. Biodegradable films were considered viable for the storage of minimally processed lettuce.

  1. Effect of biochar amendment on the control of soil sulfonamides, antibiotic-resistant bacteria, and gene enrichment in lettuce tissues

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Mao [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Sun, Mingming [Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Feng, Yanfang, E-mail: fengyanfang@163.com [Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014 (China); Wan, Jinzhong [Nanjing Institute of Environmental Science, Ministry of Environmental Protection of China, Nanjing 210042 (China); Xie, Shanni; Tian, Da [Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Zhao, Yu [Collaborative Innovation Center of Advanced Microstructures, Jiangsu Provincial Key Laboratory of Photonic and Electronic Materials, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093 (China); Wu, Jun; Hu, Feng; Li, Huixin [Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); Jiang, Xin, E-mail: Jiangxin@issas.ac.cn [State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-05-15

    Highlights: • Biochar can prevent soil sulfonamides from accumulating in lettuce tissues. • ARB enrichment in lettuce tissues decreased significantly after biochar amendment. • Impedance effect of biochar addition on soil ARGs was also quite effective. • Biochar application can be a practical strategy to protect vegetable safety. - Abstract: Considering the potential threat of vegetables growing in antibiotic-polluted soil with high abundance of antibiotic-resistant genes (ARGs) against human health through the food chain, it is thus urgent to develop novel control technology to ensure vegetable safety. In the present work, pot experiments were conducted in lettuce cultivation to assess the impedance effect of biochar amendment on soil sulfonamides (SAs), antibiotic-resistant bacteria (ARB), and ARG enrichment in lettuce tissues. After 100 days of cultivation, lettuce cultivation with biochar amendment exhibited the greatest soil SA dissipation as well as the significant improvement of lettuce growth indices, with residual soil SAs mainly existing as the tightly bound fraction. Moreover, the SA contents in roots and new/old leaves were reduced by one to two orders of magnitude compared to those without biochar amendment. In addition, isolate counts for SA-resistant bacterial endophytes in old leaves and sul gene abundances in roots and old leaves also decreased significantly after biochar application. However, neither SA resistant bacteria nor sul genes were detected in new leaves. It was the first study to demonstrate that biochar amendment can be a practical strategy to protect lettuce safety growing in SA-polluted soil with rich ARB and ARGs.

  2. Assessing the effect of sodium dichloroisocyanurate concentration on transfer of Salmonella enterica serotype Typhimurium in wash water for production of minimally processed iceberg lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Maffei, D F; Sant'Ana, A S; Monteiro, G; Schaffner, D W; Franco, B D G M

    2016-06-01

    This study evaluated the impact of sodium dichloroisocyanurate (5, 10, 20, 30, 40, 50 and 250 mg l(-1) ) in wash water on transfer of Salmonella Typhimurium from contaminated lettuce to wash water and then to other noncontaminated lettuces washed sequentially in the same water. Experiments were designed mimicking the conditions commonly seen in minimally processed vegetable (MPV) processing plants in Brazil. The scenarios were as follows: (1) Washing one inoculated lettuce portion in nonchlorinated water, followed by washing 10 noninoculated portions sequentially. (2) Washing one inoculated lettuce portion in chlorinated water followed by washing five noninoculated portions sequentially. (3) Washing five inoculated lettuce portions in chlorinated water sequentially, followed by washing five noninoculated portions sequentially. (4) Washing five noninoculated lettuce portions in chlorinated water sequentially, followed by washing five inoculated portions sequentially and then by washing five noninoculated portions sequentially in the same water. Salm. Typhimurium transfer from inoculated lettuce to wash water and further dissemination to noninoculated lettuces occurred when nonchlorinated water was used (scenario 1). When chlorinated water was used (scenarios 2, 3 and 4), no measurable Salm. Typhimurium transfer occurred if the sanitizer was ≥10 mg l(-1) . Use of sanitizers in correct concentrations is important to minimize the risk of microbial transfer during MPV washing. In this study, the impact of sodium dichloroisocyanurate in the wash water on transfer of Salmonella Typhimurium from inoculated lettuce to wash water and then to other noninoculated lettuces washed sequentially in the same water was evaluated. The use of chlorinated water, at concentration above 10 mg l(-1) , effectively prevented Salm. Typhimurium transfer under several different washing scenarios. Conversely, when nonchlorinated water was used, Salm. Typhimurium transfer occurred in

  3. THE YIELD OF LETTUCE BREEDING LINE UNDER LED LAMPS IN WINTER GREENHOUSE IN THE NORTH

    Directory of Open Access Journals (Sweden)

    I. V. Dalke

    2017-01-01

    Full Text Available The lettuce (Lactuca sativa L. is widely known and favorite vegetable crop among people. In Europe the main production of lettuce is performed on protected ground with application of  artificial  light  sources. The artificially-lighted  culture  of salad became very actually acquired in the north. Previously, on the basis of multi-year studies on yield registration and experiments with different regimes of lighting we have defined the appropriate parameters of supplementary lighting for lettuce with sodium high-pressure lamps that provided the production in different seasons per year. The aim was to study the accumulation of biomass and yield quality in lettuce ‘Aphytsion’ being grown in winter rotation under light-emitting diodes lamps. The accumulation of biomass and yield quality was studied in ‘Aphytsion’,  grown in winter rotation under lightemitting diodes lamps ECOLED-BIO-112-185WD120 UniversaLED (ООО ‘GK’  ‘CET’, Perm, in  industrial greenhouse OOO ‘Prigorodniy’  at Syktyvkar city. The commodity  output  was obtained  for  two  cycle  of  cultivation, November-December  and  December-January.  Yield  of foliage biomass was 2.4 kg/m2 with flow density PAR (Photosynthetically active radiation about 90 μmole quantum/m2  s. at 20 W/m2 with total light energy 54 MJ/m2  supplied to plants from LED lamps. The plants produced about 0.5 g. of dry weight calculated on one mole of spent light energy. Energy efficiency of PAR was 3% that corresponded with data observed earlier with sodium high-pressure lamps. The conclusion was made about the suitableness of this type of light-emitting diode lamps for lettuce cultivation in winter rotation in first photic zone. It was recommended to increase duration of supplemental lighting up to 22-24 hours in December and up to 20-22 hours in January to improve the productivity and biological value of plant output. It enables to raise RAP income in plants by 35 %, on

  4. Phytoremediation to remove nutrients and improve eutrophic stormwaters using water lettuce (Pistia stratiotes L.).

    Science.gov (United States)

    Lu, Qin; He, Zhenli L; Graetz, Donald A; Stoffella, Peter J; Yang, Xiaoe

    2010-01-01

    Water quality impairment by nutrient enrichment from agricultural activities has been a concern worldwide. Phytoremediation technology using aquatic plants in constructed wetlands and stormwater detention ponds is increasingly applied to remediate eutrophic waters. The objectives of this study were to evaluate the effectiveness and potential of water lettuce (Pistia stratiotes L.) in removing nutrients including nitrogen (N) and phosphorus (P) from stormwater in the constructed water detention systems before it is discharged into the St. Lucie Estuary, an important surface water system in Florida, using phytoremediation technologies. In this study, water lettuce (P. stratiotes) was planted in the treatment plots of two stormwater detention ponds (East and West Ponds) in 2005-2007 and water samples from both treatment and control plots were weekly collected and analyzed for water quality properties including pH, electrical conductivity, turbidity, suspended solids, and nutrients (N and P). Optimum plant density was maintained and plant samples were collected monthly and analyzed for nutrient contents. Water quality in both ponds was improved, as evidenced by decreases in water turbidity, suspended solids, and nutrient concentrations. Water turbidity was decreased by more than 60%. Inorganic N (NH(4) (+) and NO(3) (-)) concentrations in treatment plots were more than 50% lower than those in control plots (without plant). Reductions in both PO(4) (3-) and total P were approximately 14-31%, as compared to the control plots. Water lettuce contained average N and P concentrations of 17 and 3.0 g kg(-1), respectively, and removed 190-329 kg N ha(-1) and 25-34 kg P ha(-1) annually. Many aquatic plants have been used to remove nutrients from eutrophic waters but water lettuce proved superior to most other plants in nutrient removal efficiency, owing to its rapid growth and high biomass yield potential. However, the growth and nutrient removal potential are affected by many

  5. Evaluation of the oil Produced from lettuce crop cultivated under three irrigation conditions

    Directory of Open Access Journals (Sweden)

    Hassan El-Mallah, M.

    2012-10-01

    Full Text Available Three oil lettuce seed samples (lactuca Sativa LS10, LS20, LS30 were cultivated under three irrigation conditions (well, normal and water deficient conditions, after 10, 20 and 30 days respectively to evaluate their oils and to see to what extent the oil lettuce plant resists draught conditions. The oils extracted from the three seed samples were evaluated by determining eight lipid profiles using HPLC in conjunction with capillary GLC. Lettuce seed oils are characterized by high contents of linoleic and oleic acids. Of the triacyl glycerols determined, those containing linoleyl and oleyl acyles are the major ones. The whole sterol profiles include β-sitosterol (as major component followed by 7-stigmasterol, campesterol and 5-stigmasterol, which were found in all the lettuce seed oil samples but with slight differences. Furthermore, sterol patterns of the free and acylated sterols, free and acylated sterylglycosides were determined. It was found that LS30 oil has the highest tocopherol content and α-tocopherol is the only constituent in all the lettuce seed oil samples. On the other hand, the 2-position in the lettuce seed oil samples is mainly acylated by unsaturated fatty acids (98.6% namely, oleic and linoleic acids. According to these results, it can be concluded that irrigation conditions do not affect the lipid constituents of the oil and the oil lettuce plant resists draught and its lipid profiles are in agreement with those of conventional vegetable oils.

    Tres muestras de semillas de lechuga (Lactuca Sativa LS10, LS20, LS30 se cultivaron bajo tres condiciones de riego (bien regado, normal y con deficiencia de agua, después de 10, 20 y 30 días, respectivamente para evaluar sus aceites y ver hasta qué punto el aceite de la planta de lechuga resiste las condiciones de riego. Los aceites extraídos de las tres muestras de semillas se evaluó mediante la determinación de ocho perfiles de lípidos usando cromatograf

  6. Recognition of Histo-Blood Group Antigen-Like Carbohydrates in Lettuce by Human GII.4 Norovirus.

    Science.gov (United States)

    Gao, Xiang; Esseili, Malak A; Lu, Zhongyan; Saif, Linda J; Wang, Qiuhong

    2016-05-15

    Human norovirus (HuNoV) genogroup II genotype 4 (GII.4) strains account for about 80% of the gastroenteritis outbreaks in the United States. Contaminated food is a major transmission vehicle for this virus. In humans, pigs, and oysters, histo-blood group antigens (HBGAs) act as attachment factors for HuNoVs. In lettuce, although the virus-like particles (VLPs) of a GII.4 HuNoV were found to bind to cell wall carbohydrates, the exact binding site has not been investigated. Here, we show the presence of HBGA-like carbohydrates in the cell wall of lettuce. The digestion of lettuce leaves with cell wall-degrading enzymes exposed more binding sites and significantly increased the level of binding of GII.4 HuNoV VLPs. Competition assays showed that both the HBGA monoclonal antibody, recognizing the H type, and plant lectins, recognizing α-l-fucose in the H type, effectively inhibited VLP binding to lettuce tissues. Lettuce cell wall components were isolated and their NoV VLP binding characteristics were tested by enzyme-linked immunosorbent assays. The binding was inhibited by pretreatment of the lettuce cell wall materials with α-1,2-fucosidase. Collectively, our results indicate that H-type HBGA-like carbohydrates exist in lettuce tissues and that GII.4 HuNoV VLPs can bind the exposed fucose moiety, possibly in the hemicellulose component of the cell wall. Salad crops and fruits are increasingly recognized as vehicles for human norovirus (HuNoV) transmission. A recent study showed that HuNoVs specifically bind to the carbohydrates of the lettuce cell wall. Histo-blood group antigens (HBGAs) are carbohydrates and are known as the attachment factors for HuNoV infection in humans. In this study, we show the presence of HBGA-like carbohydrates in lettuce, to which HuNoVs specifically bind. These results suggest that specifically bound HuNoVs cannot be removed by simple washing, which may allow viral transmission to consumers. Our findings provide new information needed

  7. Effect of processing on the disappearance of pesticide residues in fresh-cut lettuce: Bioavailability and dietary risk.

    Science.gov (United States)

    Camara, Miguel A; Barba, Alberto; Cermeño, Sandra; Martinez, Gracia; Oliva, Jose

    2017-12-02

    The aim of this research is to establish the processing factors of six pesticides durong the preparation of fresh-cut lettuce and to assess the risk of ingestion of pesticide residues associated with the consumption of the same. A field study was carried out on the dissipation of three insecticides (imidacloprid, tebufenozide, cypermethrin) and three fungicides (metalaxyl, tebuconazole, azoxystrobin) during treatment conditions simulating those used for commercial fresh-cut lettuce. A simultaneous residue analysis method is validated using QuEChERS extraction with acetonitrile and CG-MS and LC-MS/MS analysis. The residues detected after field application never exceed the established Maximum Residue Limits. The processing factors were generally less than 1 (between 0.34 for tebufenozide and 0.53 for imidacloprid), indicating that the process, as a whole, considerably reduces residue levels in processed lettuce compared to fresh lettuce. It is confirmed that cutting, followed by washing and drying, considerably reduces the residues. A matrix effect in the dialyzation of the pesticides is observed and the in vitro study of bioavailability establishes a low percentage of stomach absorption capacity (lettuce showed no concerns for consumer health.

  8. Plant-Adapted Escherichia coli Show Increased Lettuce Colonizing Ability, Resistance to Oxidative Stress and Chemotactic Response

    Science.gov (United States)

    Dublan, Maria de los Angeles; Ortiz-Marquez, Juan Cesar Federico; Lett, Lina; Curatti, Leonardo

    2014-01-01

    Background Escherichia coli is a widespread gut commensal and often a versatile pathogen of public health concern. E. coli are also frequently found in different environments and/or alternative secondary hosts, such as plant tissues. The lifestyle of E. coli in plants is poorly understood and has potential implications for food safety. Methods/Principal Findings This work shows that a human commensal strain of E. coli K12 readily colonizes lettuce seedlings and produces large microcolony-like cell aggregates in leaves, especially in young leaves, in proximity to the vascular tissue. Our observations strongly suggest that those cell aggregates arise from multiplication of single bacterial cells that reach those spots. We showed that E. coli isolated from colonized leaves progressively colonize lettuce seedlings to higher titers, suggesting a fast adaptation process. E. coli cells isolated from leaves presented a dramatic rise in tolerance to oxidative stress and became more chemotactic responsive towards lettuce leaf extracts. Mutant strains impaired in their chemotactic response were less efficient lettuce colonizers than the chemotactic isogenic strain. However, acclimation to oxidative stress and/or minimal medium alone failed to prime E. coli cells for enhanced lettuce colonization efficiency. Conclusion/Significance These findings help to understand the physiological adaptation during the alternative lifestyle of E. coli in/on plant tissues. PMID:25313845

  9. Growth of wheat and lettuce and enzyme activities of soils under garlic stalk decomposition for different durations.

    Science.gov (United States)

    Han, Xu; Cheng, Zhihui; Meng, Huanwen

    2017-07-01

    Garlic (Allium sativum L.) stalk is a byproduct of garlic production that is normally thought of as waste but is now considered a useful biological resource. It is necessary to utilize this resource efficiently and reasonably to reduce environmental pollution and achieve sustainable agricultural development. The effect of garlic stalk decomposed for different durations was investigated in this study using wheat (Triticum aestivum L.) and lettuce (Lactuca sativa var. crispa L.) as test plants. Garlic stalk in early stages of decomposition inhibited the shoot and root lengths of wheat and lettuce, but it promoted the shoot and root lengths in later stages; longer durations of garlic stalk decomposition significantly increased the shoot and root fresh weights of wheat and lettuce, whereas shorter decomposing durations significantly decreased the shoot and root fresh weights; and garlic stalk at different decomposition durations increased the activities of urease, sucrase and alkaline phosphatase in soil where wheat or lettuce was planted. Garlic stalk decomposed for 30 or 40 days could promote the growth of wheat and lettuce plants as well as soil enzyme activities. These results may provide a scientific basis for the study and application of garlic stalk. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  10. Impact of relative humidity, inoculum carrier and size, and native microbiota on Salmonella ser. Typhimurium survival in baby lettuce.

    Science.gov (United States)

    López-Gálvez, Francisco; Gil, Maria Isabel; Allende, Ana

    2018-04-01

    The effects of relative humidity (RH), fluctuating climate conditions, inoculum size and carrier on the survival of Salmonella enterica serovar Typhimurium on baby lettuce in environmental test chambers were studied. Buffered peptone water (BPW), distilled water (DW), and irrigation water (IW) were compared as inoculum carriers. Additionally, survival of Salmonella in suspensions prepared using filtered and unfiltered IW was assessed. Salmonella Typhimurium survived better on baby lettuce plants at high RH independently of the inoculum size. When lettuce plants were grown under fluctuating environmental conditions, Salmonella survival was similar under both RH conditions. Regarding the inoculum carrier, the inoculated microorganism survived better on lettuce plants when BPW was used as carrier both at high and low RH. Survival rate of Salmonella in IW was affected by the presence of native microbiota. Native microbiota present in IW did not affect survival of Salmonella or the levels of mesophilic bacteria on the baby lettuce leaves. The information obtained in the present study contributes to the knowledge on the effect of environmental conditions on pathogenic bacteria survival on growing edible plants. These results are useful when selecting the methodology to carry out experimental studies on the survival of microbial pathogens under different pre-harvest conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Lettuce Allergy Is a Lipid Transfer Syndrome-Related Food Allergy With a High Risk of Severe Reactions.

    Science.gov (United States)

    Muñoz-García, E; Luengo-Sánchez, O; Moreno-Pérez, N; Cuesta-Herranz, J; Pastor-Vargas, C; Cardona, V

    Lipid transfer protein (LTP) sensitization is the most common cause of food allergy in the Mediterranean area, with peach allergy acting as the primary sensitizer in most cases. Lettuce has been described as a common offending food in patients with LTP syndrome. The aim of the study was to investigate the frequency and clinical expression of LTP syndrome in a sample of lettuceallergic patients. We determined specific IgE to Pru p 3 and lettuce in a sample of 30 patients with a diagnosis of lettuce allergy. Symptoms elicited by other LTP-containing plant-derived foods and the presence of cofactors were assessed. The clinical symptoms of lettuce allergy were frequently severe, with 18 of the 30 patients experiencing anaphylaxis. All the patients had allergic reactions to other plant foods. Cofactors were involved in the clinical reactions of 13 of the 30 patients. Sensitization to pollens was found in 90% of patients. Lettuce allergy is found not as an isolated condition but in the context of LTP syndrome and it is characterized by severe reactions and frequent cofactor association.

  12. Effect of biochar amendment on the control of soil sulfonamides, antibiotic-resistant bacteria, and gene enrichment in lettuce tissues.

    Science.gov (United States)

    Ye, Mao; Sun, Mingming; Feng, Yanfang; Wan, Jinzhong; Xie, Shanni; Tian, Da; Zhao, Yu; Wu, Jun; Hu, Feng; Li, Huixin; Jiang, Xin

    2016-05-15

    Considering the potential threat of vegetables growing in antibiotic-polluted soil with high abundance of antibiotic-resistant genes (ARGs) against human health through the food chain, it is thus urgent to develop novel control technology to ensure vegetable safety. In the present work, pot experiments were conducted in lettuce cultivation to assess the impedance effect of biochar amendment on soil sulfonamides (SAs), antibiotic-resistant bacteria (ARB), and ARG enrichment in lettuce tissues. After 100 days of cultivation, lettuce cultivation with biochar amendment exhibited the greatest soil SA dissipation as well as the significant improvement of lettuce growth indices, with residual soil SAs mainly existing as the tightly bound fraction. Moreover, the SA contents in roots and new/old leaves were reduced by one to two orders of magnitude compared to those without biochar amendment. In addition, isolate counts for SA-resistant bacterial endophytes in old leaves and sul gene abundances in roots and old leaves also decreased significantly after biochar application. However, neither SA resistant bacteria nor sul genes were detected in new leaves. It was the first study to demonstrate that biochar amendment can be a practical strategy to protect lettuce safety growing in SA-polluted soil with rich ARB and ARGs. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Concentration of phenolic compounds is increased in lettuce grown under high light intensity and elevated CO2.

    Science.gov (United States)

    Pérez-López, Usue; Sgherri, Cristina; Miranda-Apodaca, Jon; Micaelli, Francesco; Lacuesta, Maite; Mena-Petite, Amaia; Quartacci, Mike Frank; Muñoz-Rueda, Alberto

    2018-02-01

    The present study was focused on lettuce, a widely consumed leafy vegetable for the large number of healthy phenolic compounds. Two differently-pigmented lettuce cultivars, i.e. an acyanic-green leaf cv. and an anthocyanic-red one, were grown under high light intensity or elevated CO 2 or both in order to evaluate how environmental conditions may affect the production of secondary phenolic metabolites and, thus, lettuce quality. Mild light stress imposed for a short time under ambient or elevated CO 2 concentration increased phenolics compounds as well as antioxidant capacity in both lettuce cvs, indicating how the cultivation practice could enhance the health-promoting benefits of lettuce. The phenolic profile depended on pigmentation and the anthocyanic-red cv. always maintained a higher phenolic amount as well as antioxidant capacity than the acyanic-green one. In particular, quercetin, quercetin-3-O-glucuronide, kaempferol, quercitrin and rutin accumulated under high light or high CO 2 in the anthocyanic-red cv., whereas cyanidin derivatives were responsive to mild light stress, both at ambient and elevated CO 2 . In both cvs total free and conjugated phenolic acids maintained higher values under all altered environmental conditions, whereas luteolin reached significant amounts when both stresses were administered together, indicating, in this last case, that the enzymatic regulation of the flavonoid synthesis could be differently affected, the synthesis of flavones being favored. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  14. Fate and Phytotoxicity of CeO2 Nanoparticles on Lettuce Cultured in the Potting Soil Environment.

    Science.gov (United States)

    Gui, Xin; Zhang, Zhiyong; Liu, Shutong; Ma, Yuhui; Zhang, Peng; He, Xiao; Li, Yuanyuan; Zhang, Jing; Li, Huafen; Rui, Yukui; Liu, Liming; Cao, Weidong

    2015-01-01

    Cerium oxide nanoparticles (CeO2 NPs) have been shown to have significant interactions in plants. Previous study reported the specific-species phytotoxicity of CeO2 NPs by lettuce (Lactuca sativa), but their physiological impacts and vivo biotransformation are not yet well understood, especially in relative realistic environment. Butterhead lettuce were germinated and grown in potting soil for 30 days cultivation with treatments of 0, 50, 100, 1000 mg CeO2 NPs per kg soil. Results showed that lettuce in 100 mg·kg-1 treated groups grew significantly faster than others, but significantly increased nitrate content. The lower concentrations treatment had no impact on plant growth, compared with the control. However, the higher concentration treatment significantly deterred plant growth and biomass production. The stress response of lettuce plants, such as Superoxide dismutase (SOD), Peroxidase (POD), Malondialdehyde(MDA) activity was disrupted by 1000 mg·kg-1 CeO2 NPs treatment. In addition, the presence of Ce (III) in the roots of butterhead lettuce explained the reason of CeO2 NPs phytotoxicity. These findings demonstrate CeO2 NPs modification of nutritional quality, antioxidant defense system, the possible transfer into the food chain and biotransformation in vivo.

  15. A Comparative Study of Natural Antimicrobial Delivery Systems for Microbial Safety and Quality of Fresh-Cut Lettuce.

    Science.gov (United States)

    Hill, Laura E; Oliveira, Daniela A; Hills, Katherine; Giacobassi, Cassie; Johnson, Jecori; Summerlin, Harvey; Taylor, T Matthew; Gomes, Carmen L

    2017-05-01

    Nanoencapsulation can provide a means to effectively deliver antimicrobial compounds and enhance the safety of fresh produce. However, to date there are no studies which directly compares how different nanoencapsulation systems affect fresh produce safety and quality. This study compared the effects on quality and safety of fresh-cut lettuce treated with free and nanoencapsulated natural antimicrobial, cinnamon bark extract (CBE). A challenge study compared antimicrobial efficacy of 3 different nanoencapsulated CBE systems. The most effective antimicrobial treatment against Listeria monocytogenes was chitosan-co-poly-N-isopropylacrylamide (chitosan-PNIPAAM) encapsulated CBE, with a reduction on bacterial load up to 2 log 10 CFU/g (P lettuce was stored at 5 °C and 10 °C for 15 d. Subsequently, chitosan-PNIPAAM-CBE nanoparticles (20, 40, and 80 mg/mL) were compared to a control and free CBE (400, 800, and 1600 μg/mL) for its effects on fresh-cut lettuce quality over 15 d at 5 °C. By the 10th day, the most effective antimicrobial concentration was 80 mg/mL for chitosan-PNIPAAM-CBE, up to 2 log 10 CFU/g reduction (P lettuce shelf-life. Overall, nanoencapsulation provided a method to effectively deliver essential oil and enhanced produce safety, while creating little to no detrimental quality changes on the fresh-cut lettuce. © 2017 Institute of Food Technologists®.

  16. Fate and Phytotoxicity of CeO2 Nanoparticles on Lettuce Cultured in the Potting Soil Environment.

    Directory of Open Access Journals (Sweden)

    Xin Gui

    Full Text Available Cerium oxide nanoparticles (CeO2 NPs have been shown to have significant interactions in plants. Previous study reported the specific-species phytotoxicity of CeO2 NPs by lettuce (Lactuca sativa, but their physiological impacts and vivo biotransformation are not yet well understood, especially in relative realistic environment. Butterhead lettuce were germinated and grown in potting soil for 30 days cultivation with treatments of 0, 50, 100, 1000 mg CeO2 NPs per kg soil. Results showed that lettuce in 100 mg·kg-1 treated groups grew significantly faster than others, but significantly increased nitrate content. The lower concentrations treatment had no impact on plant growth, compared with the control. However, the higher concentration treatment significantly deterred plant growth and biomass production. The stress response of lettuce plants, such as Superoxide dismutase (SOD, Peroxidase (POD, Malondialdehyde(MDA activity was disrupted by 1000 mg·kg-1 CeO2 NPs treatment. In addition, the presence of Ce (III in the roots of butterhead lettuce explained the reason of CeO2 NPs phytotoxicity. These findings demonstrate CeO2 NPs modification of nutritional quality, antioxidant defense system, the possible transfer into the food chain and biotransformation in vivo.

  17. Synergy between chemical and biological control in the IPM of currant-lettuce aphid (Nasonovia ribisnigri) in Canterbury, New Zealand.

    Science.gov (United States)

    Fagan, L L; McLachlan, A; Till, C M; Walker, M K

    2010-04-01

    Field trials were conducted at four Canterbury, New Zealand locations in 2005-06 to determine if the synergistic effects of biological control by natural enemies and standard drenching techniques controlled lettuce aphid populations throughout the entire growing season. Chemical usage significantly lowered aphid densities in the outer, wrapper and heart leaves compared to control plants at most times. However, in mid-summer, natural enemies, such as the brown lacewing (Micromus tasmaniae), 11-spotted ladybird beetle (Coccinella undecimpunctata) and small hoverfly larvae (Melanostoma fasciatum), were more than sufficient to control lettuce aphids without the use of insecticides. Drenching, in addition to natural enemy attack, appears to be required in early spring and late summer to maintain very low levels of lettuce aphid. Given the potential for imidacloprid resistance to develop, it may be advisable to restrict drenches to these key periods in order to allow populations of natural enemies to maintain control of prey populations. We recommend industry support the validation of action thresholds across different regions within New Zealand and focus on the seasonal biology of predators to assist growers with the sustainable long-term control of lettuce aphids. The inclusion of additional data into an economic model to compare pest damage with predator loading would be useful for growers in managing aphid problems. These results will assist in the continued improvement and development of a sustainable IPM strategy for lettuce aphids in New Zealand and elsewhere.

  18. The use of lytic bacteriophages to reduce E. coli O157:H7 on fresh cut lettuce introduced through cross-contamination

    Science.gov (United States)

    The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield) at 108 PFU/ml or a control (phosphate buffered saline, PBS) was applied to lettuce by either 1) spraying on to lettuce piec...

  19. Escherichia coli O157:H7 converts plant-derived choline to glycine betaine for osmoprotection during pre- and post-harvest colonization of injured lettuce leaves

    Science.gov (United States)

    The opportunistic colonization of damaged plant tissue by human enteric pathogens may contribute to the occurrence of outbreaks of foodborne illness linked to produce. E. coli O157:H7 (EcO157) responds to physicochemical stresses in cut lettuce and lettuce lysates by upregulation of several stress r...

  20. Low intensity monochromatic red, blue or green light increases the carbohydrate levels and substantially extends the shelf life of fresh-cut lettuce

    NARCIS (Netherlands)

    Woltering, E.J.; Seifu, Y.W.

    2015-01-01

    During dark storage of fresh-cut product prepared from butterhead and iceberg lettuce the levels of carbohydrates (glucose, fructose, sucrose, starch) decrease. Carbohydrate levels were low in butterhead lettuce at the start [~20 mg/g dry matter (DW)] and levels decreased by over 50% during storage

  1. Influence of the temporal and spatial variation of nitrate reductase, glutamine synthetase and soil composition in the N species content in lettuce (Lactuca sativa).

    Science.gov (United States)

    Pinto, Edgar; Fidalgo, Fernanda; Teixeira, Jorge; Aguiar, Ana A; Ferreira, Isabel M P L V O

    2014-04-01

    The variation of nitrate reductase (NR), glutamine synthetase (GS) and N content in lettuce was evaluated at 5 stages of lettuce growth. Soil physicochemical properties and its N content were also assessed to elucidate the soil-to-plant transfer of inorganic N and potential leaching to groundwater. A decrease of NR activity and an increase of NO3(-) and N-Kjeldahl content in lettuces were observed during plant growth, whereas GS activity and NH4(+) increased during the first few weeks of lettuce growth and then decreased. Although the temporal variation was similar in lettuces grown in different soils, quantitative differences were observed, indicating that high NO3(-) content in soil caused a higher NO3(-) accumulation in lettuce despite the higher NR activity during the initial stage of plant growth. Higher levels of NO3(-) and NH4(+) were correlated with higher levels of N-Kjeldahl in lettuce suggesting a positive effect of these N species in the biosynthesis of organic forms of N. Soil physicochemical properties influenced the mobility of inorganic N within the groundwater-soil-plant system. Sandy soils with low OM content allowed NO3(-) leaching, which was confirmed by higher NO3(-) levels in groundwater. Therefore, lettuces grown in those soils presented lower N content and the inputs of N to the environment were higher. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. LCM-seq reveals the crucial role of LsSOC1 in heat-promoted bolting of lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Chen, Zijing; Zhao, Wensheng; Ge, Danfeng; Han, Yingyan; Ning, Kang; Luo, Chen; Wang, Shenglin; Liu, Renyi; Zhang, Xiaolan; Wang, Qian

    2018-05-17

    Lettuce (Lactuca sativa L.) is one of the most economically important vegetables. The floral transition in lettuce is accelerated under high temperatures, which can significantly decrease yields. However, the molecular mechanism underlying the floral tranition in lettuce is poorly known. Using laser capture microdissection coupled with RNA sequencing, we isolated shoot apical meristem cells from the bolting-sensitive lettuce line S39 at four critical stages of development. Subsequently, we screened specifically for the flowering-related gene LsSOC1 during the floral transition through comparative transcriptomic analysis. Molecular biology, developmental biology, and biochemical tools were combined to investigate the biological function of LsSOC1 in lettuce. LsSOC1 knockdown by RNA interference resulted in a significant delay in the timing of bolting and insensitivity to high temperature, which indicated that LsSOC1 functions as an activator during heat-promoted bolting in lettuce. We determined that two heat-shock transcription factors, HsfA1e and HsfA4c, bound to the promoter of LsSOC1 to confirm that LsSOC1 played an important role in heat-promoted bolting. This study indicates that LsSOC1 plays a crucial role in the heat-promoted bolting process in lettuce. Further investigation of LsSOC1 may be useful for clarification of the bolting mechanism in lettuce. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  3. Expression analysis of polyphenol oxidase isozymes by active staining method and tissue browning of head lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Noda, Takahiro; Iimure, Kazuhiko; Okamoto, Shunsuke; Saito, Akira

    2017-08-01

    Browning of plant tissue is generally considered attributable to enzymatic oxidation by polyphenol oxidase (PPO). Electrophoresis followed by activity staining has been used as an effective procedure to visually detect and isolate isozymes; however, it has not been applied for examination of various PPO isozymes in lettuce. Our study demonstrated that different lettuce PPO isozymes could be detected at different pH in active staining, and multiple isozymes were detected only under alkaline conditions. As a result, we concluded that activity staining with approximately pH 8 enabled to detect various PPO isozymes in lettuce. By expression analysis of the PPO isozymes after wounding, PPO isozymes that correlated with time-course of tissue browning were detected. The wound-induced PPO may play a key role in enzymatic browning.

  4. Rhizonin A from Burkholderia sp. KCTC11096 and Its Growth Promoting Role in Lettuce Seed Germination

    Directory of Open Access Journals (Sweden)

    Sang-Mo Kang

    2012-07-01

    Full Text Available We isolated and identified a gibberellin-producing Burkholderia sp. KCTC 11096 from agricultural field soils. The culture filtrate of plant growth promoting rhizobacteria (PGPR significantly increased the germination and growth of lettuce and Chinese cabbage seeds. The ethyl acetate extract of the PGPR culture showed significantly higher rate of lettuce seed germination and growth as compared to the distilled water treated control. The ethyl acetate fraction of the Burkholderia sp. was subjected to bioassay-guided isolation and we obtained for the first time from a Burkholderia sp. the plant growth promoting compound rhizonin A (1, which was characterized through NMR and MS techniques. Application of various concentrations of 1 significantly promoted the lettuce seed germination as compared to control.

  5. Effect of variety, processing, and storage on the flavonoid glycoside content and composition of lettuce and endive.

    Science.gov (United States)

    DuPont, M S; Mondin, Z; Williamson, G; Price, K R

    2000-09-01

    Eight varieties of lettuce (Lactuca sativum) and three varieties of endive (Cichorium endivia) were analyzed for flavonoid composition and content. Total flavonoid contents, expressed as units of aglycon for fresh material, were in the ranges of 0.3-229 microg/g for lettuce and 44-248 microg/g for endive. Five quercetin conjugates [quercetin 3-O-galactoside, quercetin 3-O-glucoside, quercetin 3-O-glucuronide, quercetin 3-O-(6-O-malonyl)glucoside, and quercetin 3-O-rhamnoside] and luteolin 7-O-glucuronide were measured in the green-leafed lettuce and an additional two cyanidin conjugates [cyanidin 3-O-glucoside and cyanidin 3-O-[(6-O-malonyl)glucoside

  6. Evidence of Protaphorura fimata (Collembola: Poduromorpha: Onychiuridae) feeding on germinating lettuce in the Salinas Valley of California.

    Science.gov (United States)

    Joseph, Shimat V; Bettiga, Christopher; Ramirez, Christian; Soto-Adames, Felipe N

    2015-02-01

    A series of experiments were conducted to determine the impact of Protaphorura fimata Gisin (Family: Onychiuridae) feeding on seeds and germinating seedlings of lettuce, Lactuca sativa L. (Asteraceae). First, various densities of P. fimata were incubated with 25 lettuce seeds for 7 d and feeding injury was evaluated in three soilless arena experiments. As a second step, 100 P. fimata were incubated with 25 lettuce seeds in three arena experiments with soil media. Finally, in a commercial field the incidence and impact of P. fimata on recently planted lettuce was assessed following applications of pyrethroid-insecticides: 2 d before planting, at planting, and 20 d later. In experiments without soil, the number of ungerminated seeds, feeding injury sites, and plants with injury were significantly greater in arenas with P. fimata than without. Similarly, the number of germinated seedlings, shoot fresh, and dry weights, and the length and width of fully opened-leaves were greater in arenas without than with P. fimata in assays with soil. In the field, P. fimata densities were significantly lower in beds that received insecticides at 2 d before and at planting than in untreated beds. Also, the fresh and dry weights of lettuce plants were significantly greater in the beds that received insecticide than in untreated. The results clearly show that P. fimata is a pest of lettuce and can cause severe feeding injury to germinating seeds or seedlings, thereby reducing their growth rate. The potential implications of P. fimata feeding and feeding injury characteristics are discussed. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Chitin mixed in potting soil alters lettuce growth, the survival of zoonotic bacteria on the leaves and associated rhizosphere microbiology.

    Directory of Open Access Journals (Sweden)

    Jane eDebode

    2016-04-01

    Full Text Available Chitin is a promising soil amendment for improving soil quality, plant growth and plant resilience. The objectives of this study were twofold. First, to study the effect of chitin mixed in potting soil on lettuce growth and on the survival of two zoonotic bacterial pathogens, Escherichia coli O157:H7 and Salmonella enterica on the lettuce leaves. Second, to assess the related changes in the microbial lettuce rhizosphere, using phospholipid fatty acid (PLFA analysis and amplicon sequencing of a bacterial 16S rRNA gene fragment and the fungal ITS2. As a result of chitin addition, lettuce fresh yield weight was significantly increased. S. enterica survival in the lettuce phyllosphere was significantly reduced. The E. coli O157:H7 survival was also lowered, but not significantly. Moreover, significant changes were observed in the bacterial and fungal community of the lettuce rhizosphere. PLFA analysis showed a significant increase in fungal and bacterial biomass. Amplicon sequencing showed no increase in fungal and bacterial biodiversity, but relative abundances of the bacterial phyla Acidobacteria, Verrucomicrobia, Actinobacteria, Bacteroidetes, and Proteobacteria and the fungal phyla Ascomycota, Basidiomycota, and Zygomycota were significantly changed. More specifically, a more than tenfold increase was observed for operational taxonomic units (OTUs belonging to the bacterial genera Cellvibrio, Pedobacter, Dyadobacter, and Streptomyces and to the fungal genera Lecanicillium and Mortierella. These genera include several species previously reported to be involved in biocontrol, plant growth promotion, the nitrogen cycle and chitin degradation. These results enhance the understanding of the response of the rhizosphere microbiome to chitin amendment. Moreover, this is the first study to investigate the use of soil amendments to control the survival of S. enterica on plant leaves.

  8. The Lettuce infectious yellows virus (LIYV)-encoded P26 is associated with plasmalemma deposits within LIYV-infected cells

    International Nuclear Information System (INIS)

    Medina, V.; Sudarshana, M.R.; Tian, T.; Ralston, K.S.; Yeh, H.-H.; Falk, B.W.

    2005-01-01

    Cytological, immunological, and mutagenesis approaches were used to identify the viral factors associated with the formation of plasmalemma deposits (PLDs) in whole plants and protoplasts infected by Lettuce infectious yellows virus (LIYV). Transmission electron microscopy and immunogold labeling using polyclonal antibodies to four of the five LIYV RNA 2-encoded large proteins, capsid protein (CP), minor capsid protein (CPm), HSP70 homolog (HSP70h), and P59, showed specific labeling of LIYV virions or virion aggregates around the vesiculated membranous inclusions, but not PLDs in LIYV-infected Nicotiana benthamiana, Nicotiana clevelandii, Lactuca sativa, and Chenopodium murale plants, and Nicotiana tabacum protoplasts. In contrast, antibodies to the RNA 2-encoded P26 showed specific labeling of PLDs but not virions in both LIYV-infected plants and protoplasts. Virion-like particles (VLPs) were seen in protoplasts infected by all LIYV RNA 2 mutants except for the CP (major capsid protein) mutant. PLDs were more difficult to find in protoplasts, but were seen in protoplasts infected by the CP and CPm mutants, but not in protoplasts infected by the P26, HSP70h, or P59 mutants. Interestingly, although the CPm mutant showed VLPs and PLDs, the PLDs did not show associated virions/virion-like particles as was always observed for PLDs seen in protoplasts infected by wild-type LIYV. Immunoblot analyses performed on purified LIYV virions showed that P26 was not detected with purified virions, but was detected in the cell wall, 1000 g and 30,000 g pellet fractions of LIYV-infected plants. These data suggest that P26 is associated with the LIYV-induced PLDs, and in contrast to the other RNA 2-encoded large proteins, P26 is not a virion protein

  9. Production and photosynthetic activity of Mimosa Verde and Mimosa Roxa lettuce in two farming systems

    Directory of Open Access Journals (Sweden)

    Aline Mabel Rosa

    2014-08-01

    Full Text Available Lettuce (Lactuca sativa L. is the most commonly consumed leaf vegetable in the Brazilian diet, and it is a good source of vitamins and minerals. It is widely grown in the conventional farming system. However, the hydroponic farming system has been gaining importance in the market, wining confidence from consumers, who are becoming increasingly more demanding on food quality. The objective of this study was to evaluate the performance of two lettuce cultivars on hydroponic and conventional farming systems for the production of fresh mass (FM and dry mass (DM, photosynthesis, contents of chlorophyll and anthocyanin. The following two experiments were carried out: hydroponics farming (HF and conventional farming (CF, performed in protect and unprotect environments, respectively, in Florianópolis, SC. Mimosa Verde cultivar (MV showed greater fresh mass than Mimosa Roxa (MR, in both farming systems and the two cultivars presented better performance in the hydroponic system (287.7 g MV and 139.1 g MR than the conventional system (129.7 g MV and 111.8 g MR. Mimosa Verde cultivar presented lower average contents of total chlorophyll (7.7 mg g-¹ FM than Mimosa Roxa (11.8 mg g-¹FM, and both cultivars displayed higher means for this variable in the hydroponic farming system. Mimosa Roxa presented higher contents of anthocyanin in the conventional system (88.24 mg g-¹ FM than the ones in the hydroponic system (36.89 mg g-¹ FM. The best results for CO2 net assimilation rate regarded to photosyntheticaly active photon flux density were found in the hydroponic system, for both lettuce cultivars. Variation in the contents of chlorophyll were also found. Those variations were higher in the protected system than in the hydroponic system and contents of anthocyanin were higher in the conventional system.

  10. Weather variability influences color and phenolic content of pigmented baby leaf lettuces throughout the season.

    Science.gov (United States)

    Marin, Alicia; Ferreres, Federico; Barberá, Gonzalo G; Gil, María I

    2015-02-18

    The lack of consistency in homogeneous color throughout the season of pigmented baby leaf lettuce is a problem for growers because of the rejection of the product and consequently the economic loss. Changes in color as well as individual and total phenolic composition and content as a response to the climatic variables were studied following the analysis of three pigmented baby leaf lettuces over 16 consecutive weeks from February to May, which corresponded to the most important production season in winter in Europe. Color and phenolic content were significantly (P ≤ 0.001) affected by cultivar, harvest week, and climatic variables that occurred in the last week before harvest. Radiation and temperature showed positive correlations with the content of phenolic acids and flavonoids that increased in all three cultivars as the season progressed. Cyanidin-3-O-(6''-O-malonyl)-glucoside content showed positive correlations with temperature and radiation but only in Batavia cultivars whereas in red oak leaf the correlation was with cold temperatures. Regarding hue angle, a positive correlation was shown with the number of hours at temperatures lower than 7 °C. A relationship between hue angle and the content of anthocyanins was not possible to establish. These results suggest that the colorimetric measurement of color cannot be used as a good indicator of anthocyanin accumulation because other pigments such as chlorophylls and carotenoids may contribute as well to the leaf color of pigmented lettuce. This study provides information about the impact of genotype and environment interactions on the biosynthesis of phenolic compounds to explain the variability in the leaf color and product appearance.

  11. Elucidating the genetic basis of antioxidant status in lettuce (Lactuca sativa).

    Science.gov (United States)

    Damerum, Annabelle; Selmes, Stacey L; Biggi, Gaia F; Clarkson, Graham Jj; Rothwell, Steve D; Truco, Maria José; Michelmore, Richard W; Hancock, Robert D; Shellcock, Connie; Chapman, Mark A; Taylor, Gail

    2015-01-01

    A diet rich in phytonutrients from fruit and vegetables has been acknowledged to afford protection against a range of human diseases, but many of the most popular vegetables are low in phytonutrients. Wild relatives of crops may contain allelic variation for genes determining the concentrations of these beneficial phytonutrients, and therefore understanding the genetic basis of this variation is important for breeding efforts to enhance nutritional quality. In this study, lettuce recombinant inbred lines, generated from a cross between wild and cultivated lettuce (Lactuca serriola and Lactuca sativa, respectively), were analysed for antioxidant (AO) potential and important phytonutrients including carotenoids, chlorophyll and phenolic compounds. When grown in two environments, 96 quantitative trait loci (QTL) were identified for these nutritional traits: 4 for AO potential, 2 for carotenoid content, 3 for total chlorophyll content and 87 for individual phenolic compounds (two per compound on average). Most often, the L. serriola alleles conferred an increase in total AOs and metabolites. Candidate genes underlying these QTL were identified by BLASTn searches; in several cases, these had functions suggesting involvement in phytonutrient biosynthetic pathways. Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity. Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes. These results offer exciting opportunities to improve the nutritional

  12. Quantitative trait loci associated with longevity of lettuce seeds under conventional and controlled deterioration storage conditions.

    Science.gov (United States)

    Schwember, Andrés R; Bradford, Kent J

    2010-10-01

    Lettuce (Lactuca sativa L.) seeds have poor shelf life and exhibit thermoinhibition (fail to germinate) above ∼25°C. Seed priming (controlled hydration followed by drying) alleviates thermoinhibition by increasing the maximum germination temperature, but reduces lettuce seed longevity. Controlled deterioration (CD) or accelerated ageing storage conditions (i.e. elevated temperature and relative humidity) are used to study seed longevity and to predict potential seed lifetimes under conventional storage conditions. Seeds produced in 2002 and 2006 of a recombinant inbred line (RIL) population derived from a cross between L. sativa cv. Salinas×L. serriola accession UC96US23 were utilized to identify quantitative trait loci (QTLs) associated with seed longevity under CD and conventional storage conditions. Multiple longevity-associated QTLs were identified under both conventional and CD storage conditions for control (non-primed) and primed seeds. However, seed longevity was poorly correlated between the two storage conditions, suggesting that deterioration processes under CD conditions are not predictive of ageing in conventional storage conditions. Additionally, the same QTLs were not identified when RIL populations were grown in different years, indicating that lettuce seed longevity is strongly affected by production environment. Nonetheless, a major QTL on chromosome 4 [Seed longevity 4.1 (Slg4.1)] was responsible for almost 23% of the phenotypic variation in viability of the conventionally stored control seeds of the 2006 RIL population, with improved longevity conferred by the Salinas allele. QTL analyses may enable identification of mechanisms responsible for the sensitivity of primed seeds to CD conditions and breeding for improved seed longevity.

  13. Prevalence and diversity of Salmonella enterica in water, fish and lettuce in Ouagadougou, Burkina Faso.

    Science.gov (United States)

    Traoré, Oumar; Nyholm, Outi; Siitonen, Anja; Bonkoungou, Isidore Juste O; Traoré, Alfred S; Barro, Nicolas; Haukka, Kaisa

    2015-07-31

    This study investigated the prevalence, serotypes and antimicrobial sensitivity patterns of Salmonella enterica in environment in Ouagadougou, Burkina Faso. A total of 476 samples, consisting of 36 samples of tap water, 51 samples of well water, 87 samples of channel water, 44 samples of reservoir water, 238 samples of fish, and 20 samples of lettuce were examined using standard bacteriological procedures for Salmonella. Salmonella were isolated from 98 samples. Salmonella were rare in drinking water, since they were not found at all from the tap water, and only in 2 % of well water. Salmonella were more common in the water of reservoir of Tanghin (15 %), reservoir of Yamtenga (20 %), and in the water channels in the city (from 20 to 31 %). Salmonella were commonly isolated from the fish (24 %) caught from the reservoir of Tanghin and from the lettuce (50 %) irrigated with water from Tanghin. The Salmonella isolates were found to represent 50 different serotypes. The 11 most common serotypes were Salmonella Bredeney and S. Colindale (both 8.2 %), S. Muenster (6.1 %), S. Korlebu (5.1 %), S. Eastbourne and S. Poona (both 4.1 %), and S. Agona, S. Derby, S. Drac, S. Senftenberg, S. Waycross (each 3.1 %), accounting for 51.3 % of all the isolates. In general, the Salmonella strains were sensitive to the antimicrobials tested, but two strains were resistant to streptomycin and many more intermediate to streptomycin or sulphonamide. This study highlights the common prevalence of Salmonella and the high diversity of Salmonella serotypes in aquatic environment in Ouagadougou, Burkina Faso. Therefore, various human activities linked to water and consumption of water-related products, such as fish and lettuce, can lead to human Salmonella infections.

  14. [Effects of LED spectrum combinations on the absorption of mineral elements of hydroponic lettuce].

    Science.gov (United States)

    Chen, Xiao-Li; Guo, Wen-Zhong; Xue, Xu-Zhang; Mmanake Beauty, Morewane

    2014-05-01

    Lettuce (Lactuca sativa) was hydroponically cultured in a completely enclosed plant factory, in which spectrum proportion-adjustable LED panels were used as sole light source for plant growth. Absorption and content of eleven mineral elements such as K, P, Ca, Mg, Na, Fe, Mn, Zn, Cu, B and Mo in Lactuca sativa under different spectral component conditions were studied by ICP -AES technology. The results showed that: (1) Single or combined spectrums corresponding to the absorbing peaks of chlorophyll a and b (450, 660 nm) could enhance the absorbing ability of roots especially for mineral elements Na, Fe, Mn, Cu and Mo, the single red spectrum had the most significant promoting effect under which contents of those four elements were respectively 7. 8, 4. 2, 4. 0 and 3. 7 times more than that under FL; (2) Absorption of K and B was the highest under FL which was 10. 309 mg g-1 and 32. 6 microg g-1 while the values decreased significantly under single or combined spectrum of red and blue; (3) Plants grown under single blue spectrum had the lowest absorption of Ca and Mg which respectively decreased by 35% and 33% than FL; (4) Lettuce grown under the spectrum combination of 30% blue and 70% red had the highest accumulations of biomass while those grown under 20% blue and 80% red had the highest accumulations of the following seven elements Ca, Mg, Na, Fe, Mn, Zn and B. The results provided theoretical basis for adjusting nutrient solution formula and selecting light spectrum of hydroponic lettuce.

  15. Dependence of plant biometrics of cutting lettuce (Lactuca sativa L. varietis on the concentration of microfertilizer Avatar-1

    Directory of Open Access Journals (Sweden)

    В. Б. Кутовенко

    2017-09-01

    Full Text Available Purpose. To investigate the variability of plant biometrics of cutting lettuce (Lactuca sativa L. varieties depending on the concentration of microfertilizer Avatar-1. Methods. Field study, biometric technique, comparative approach, statistical evaluation, generalization. Results. Dependence of the plant height, the diameter of the leaf rosette, the number of leaves per plant, the leaf area of plants on the concentration of microfertilizer Avatar-1 was defined. Investigations of cutting lettuce ‘Afitsyon’ and ‘Concord’ varieties by Dutch breeding were conducted in 2016–2017 in the collection sites of the department of vegetable growing in the scientific-experimental field  “Fruit and vegetable garden” of the National University of Life and Environmental Sciences of Ukraine. In order to determine dependence of plant biometrics of cutting lettuce varieties on the concentration of complex microfertilizer Avatar-1, the following scheme was used for the both varieties: variant 1 – water (control; variant 2 – 0,10% solution; variant 3 – 0,25% solution; variant 4 – 0,50% solution. Plants were treated with microfertilizer three times during the vegetative period. Alterations of plant biometrics of cutting lettuce ‘Afitsyon’ and ‘Concord’ varieties  depending on the concentration of complex microfertilizer Avatar-1 was studied. Conclusions. It was found that in case of three-time plant treatment with complex microfertilizer Avatar-1 at the time of harvesting, the best plant biometrics was registered in variant 3 (concentration 0,25% for the both ‘Afitsyon’ and ‘Concord’ varie­ties of cutting lettuce. The height of plants of the cutting lettuce in ‘Afitsyon’ variety exceeded this figure in ‘Concord variety by 1,1–1,4 cm. The concentration of microfertilizer had no significant effect on the diameter of the leaf rosette of ‘Concord’ variety (25,1–25,9 см. The diame­ter of the leaf rosette of

  16. Growth and Tissue Elemental Composition Response of Butterhead Lettuce (Lactuca sativa, cv. Flandria) to Hydroponic and Aquaponic Conditions

    OpenAIRE

    Tyler S. Anderson; David de Villiers; Michael B. Timmons

    2017-01-01

    The primary objective of this research was to compare lettuce performance under conventional hydroponics at pH 5.8 (referred to as H5), hydroponics at pH 7.0 (referred to as H7), and recirculated aquaponic water at pH 7.0 (referred to as A7). Aquaponic nutrients were supplied by continuously recirculating water between a fish rearing system (recirculating aquaculture system or RAS) and the lettuce growing system (with the sole addition being chelated iron). This paper builds upon our previous...

  17. Factors important for the shelf-life of minimally processed lettuce

    OpenAIRE

    Deza Durand, Karla Michelle

    2013-01-01

    The minimally processed vegetable industry has been increasing rapidly due to change in lifestyle. Both women and men work outside home and have less time to cook and need more convenience and time saving products, which also present fresh and healthy characteristics. Iceberg lettuce (Lactuca sativa L.) is one of the most popular fresh-cut vegetables. Although an increase in the number of mixed salads in retail food chains is evident, their short shelf-life due to rapid browning and off-odour...

  18. Impact of solar radiation exposure on phyllosphere bacterial community of red-pigmented baby leaf lettuce.

    Science.gov (United States)

    Truchado, Pilar; Gil, M Isabel; Reboleiro, Patricia; Rodelas, Belén; Allende, Ana

    2017-09-01

    Solar radiation has been identified as a stress factor affecting phyllosphere associated bacteria colonization and survival during primary production. In the present study, the impact of different solar radiation doses on the phyllosphere microbiota of red-pigmented baby leaf lettuce cultivated in open field under commercial conditions was evaluated. Four weeks before harvest, the growing field was divided into four plots; each one was consecutively covered with one-week-interval with a light-excluding plastic to reduce the sunlight exposure. Four different solar radiation treatments were generated and cumulative photosynthetically active radiation (PAR) was used to differentiate treatments as follows: 4889 ± 428 μmol/m 2 /s (uncovered), 4265 ± 356 μmol/m 2 /s (covered for 1 week), 3602 ± 225 μmol/m 2 /s (covered for 2 weeks) and 3115 ± 313 μmol/m 2 /s (covered for 3 weeks). The size and composition of the phyllosphere bacterial community were determined by cultivation-depended (plate count) and independent (qPCR) techniques. Exposure to decreased levels of cumulative PAR did not produce significant differences in total bacterial community size, regardless of the chosen quantification techniques. However, total bacteria size quantified by qPCR was around 3.5 orders of magnitude higher than those obtained by plate count. The observed differences between cultivation-depended and independent techniques could be attributed to the presence of non-viable or viable but non-culturable (VBNC) bacteria. The bacterial community structure was analyzed using temperature gradient gel electrophoresis (TGGE), and significant differences were detected when the four solar treatment were compared. A qPCR approach was applied to the quantification of specific bacterial phyla and classes, previously identified in the phyllosphere of plants available literature, confirming that Proteobacteria, Bacteroidetes, Actinobacterias and Firmicutes were the most abundantly

  19. Non-destructive monitoring of agricultural product (lettuce [Lactuca sativa]) based on laser-induced fluorescence

    International Nuclear Information System (INIS)

    Ishizawa, H.; Saito, Y.; Amemiya, T.; Komatu, K.

    2002-01-01

    Quality control of agricultural products in process of cultivation and distribution has become an important problem. This paper describes a field measuring method of lettuce based on laser induced fluorescence (LIF) spectroscopy for growth monitoring. Intensity at 460nm of LIF spectra showed characteristic variations of near harvest time. The results of chemical analysis confirmed that sucrose and chlorogenic acid are origins of the 460nm fluorescence. The prediction of harvest time and the possibility of quality monitoring are discussed based on the experimental data

  20. Base documentaire sur les artisanats gallo-romains en Lyonnaise et dans les cités du nord et de l’est de l’Aquitaine : Corpus de données. Présentation Documentary base on the Gallo-Roman craft industries in the Lyonnaise region and the cities of North and East Aquitaine: Data base – presentation

    Directory of Open Access Journals (Sweden)

    Alain Ferdière

    2009-05-01

    Full Text Available Un important corpus de tout type d’artisanat pour la période romaine a été constitué et est ici accessible en lien : il concerne l’ensemble de la province romaine de Lyonnaise (du Finistère au Lyonnais, ainsi que les cités du nord et de l’est de la grande Aquitaine, des Pictons à l’ouest au Gabales au sud-est. Ce corpus examine, par type d’artisanat, essentiellement les contextes (types de sites, chronologie, et non les aspects techniques ou typologiques concernant ces artisanats.An important body of all types of craft industries has been built up for the Roman period and is accessible here in context: it concerns the whole of the Lyonnaise Roman province (from Finistère to Lyonnais as well as the cities of the north and of greater Aquitaine, from the Pictons to the west to the Gabales to the south-east. This body essentially examines for each type of craft industry the contexts (type of site, chronology and not the technical aspects or typologies concerning the craft industries.

  1. Enhanced Accumulation of Vitamins, Nutraceuticals and Minerals in Lettuces Associated with Arbuscular Mycorrhizal Fungi (AMF: A Question of Interest for Both Vegetables and Humans

    Directory of Open Access Journals (Sweden)

    Marouane Baslam

    2013-03-01

    Full Text Available Lettuce (Lactuca sativa L. is extensively grown and is the most widely used food crop for the called “Fourth Range” of vegetables. Lettuce exhibits healthy properties mainly due to the presence of antioxidant compounds (vitamins C and E, carotenoids, polyphenols alongside significant fibre content and useful amounts of certain minerals. Lettuce can establish a mutualistic association with arbuscular mycorrhizal fungi (AMF. The establishment of the symbiosis involves a continuous cellular and molecular dialogue between both symbionts, which includes the activation of antioxidant, phenylpropanoid or carotenoid metabolic pathways. The presence of AMF colonizing roots of greenhouse-grown lettuces can induce an accumulation of secondary metabolites, vitamins and minerals in leaves that overcome the dilution effect due to the increased size of mycorrhizal plants. Therefore, AMF would allow the intake of minerals and compounds with antioxidant properties to be enhanced without increasing the consumption of lettuce in the diet. In addition, increased quantities of secondary metabolites may help lettuce plants to withstand biotic and abiotic stresses. Our review discusses the influence exerted by several environmental factors and agronomic practices on the ability of AMF for enhancing the levels of vitamins, nutraceuticals and minerals in leaves of green and red-leaf types of lettuces.

  2. Liquid chromatography-tandem mass spectrometry method for simultaneous quantification of azoxystrobin and its metabolites, azoxystrobin free acid and 2-hydroxybenzonitrile, in greenhouse-grown lettuce.

    Science.gov (United States)

    Gautam, Maheswor; Fomsgaard, Inge S

    2017-12-01

    Lettuce is an important part of the diet in Europe. The permitted levels of pesticides in lettuce are strictly regulated and there is growing urge among food safety authorities to analyse pesticide metabolites as well. Azoxystrobin is one of pesticides that is frequently detected in lettuce. Although there are several analytical methods for the determination of azoxystrobin in lettuce, a sensitive method for the determination of its metabolites in lettuce is lacking. This study aimed at developing an extraction and LC-MS/MS method for the simultaneous determination of azoxystrobin, and its metabolites azoxystrobin free acid and 2-hydroxybenzonitrile in lettuce. Accelerated solvent extraction, QuEChERS extraction, and shaking extraction were compared using various solvents. The final method consisted of shaking freeze-dried sample in 0.1% formic acid in 80% aqueous acetonitrile. The selected method was validated by spiking each analyte at 125 ng/g and 500 ng/g. The method resulted in acceptable recovery for 2-hydroxybenzonitrile, azoxystrobin free acid, and azoxystrobin, with a RSD of lettuce.

  3. Consórcios alface-cenoura e alface-rabanete sob manejo orgânico Intercropping of lettuce-carrot and lettuce-radish under organic management

    Directory of Open Access Journals (Sweden)

    Ailena Sudo Salgado

    2006-07-01

    Full Text Available Dois experimentos foram conduzidos, por dois anos consecutivos, em Seropédica, RJ, com o objetivo de avaliar o desempenho agronômico dos consórcios das cultivares de alface 'Regina 71' (lisa e 'Verônica' (crespa com cenoura 'Brasília' e rabanete 'Híbrido nº 19', sob manejo orgânico, assim como determinar as quantidades de macronutrientes exportadas. O delineamento experimental usado foi o de blocos ao acaso, com quatro repetições. No primeiro experimento, os tratamentos consistiram de alface crespa em consórcio com cenoura, alface crespa em consórcio com rabanete e os cultivos solteiros. No segundo experimento, usou-se alface lisa em lugar da crespa. Nos consórcios entre cenoura e alface crespa ou lisa, foram observados índices de uso eficiente da terra, superiores a 1,60. Nos consórcios de rabanete com alface, crespa ou lisa, esses índices foram de 1,54 e 1,27, respectivamente. As quantidades de nutrientes extraídas do sistema pelos produtos colhidos foram inferiores aos aportes efetuados, evidenciando a viabilidade de qualquer dos consórcios avaliados.Two experiments were carried out, in two consecutive years, at Seropédica, RJ, Brazil, aiming to evaluate the agronomic performance of intercropping of lettuce cvs. Regina 71 (smooth leaf and Verônica (crisp leaf with carrot (cv. Brasília and radish (cv. Hybrid number 19, under organic management. The amount of nutrients exported from the system by harvesting was also evaluated. The experimental design used was of completely randomized blocks, with four replications. In the first experiment, treatments consisted of lettuce with crisp leaves intercropped with carrot, lettuce with crisp leaves intercropped with radish and sole crops. In the second experiment, lettuce with smooth leaves was used instead of lettuce with crisp leaves. Intercropping of carrot and lettuce, with crisp or smooth leaf, presented land equivalent ratios higher than 1.60. Intercropping of radish and

  4. Production and characterization of cyanocobalamin-enriched lettuce (Lactuca sativa L.) grown using hydroponics.

    Science.gov (United States)

    Bito, Tomohiro; Ohishi, Noriharu; Hatanaka, Yuka; Takenaka, Shigeo; Nishihara, Eiji; Yabuta, Yukinori; Watanabe, Fumio

    2013-04-24

    When lettuces (Lactuca sativa L.) grown for 30 days in hydroponic culture were treated with various concentrations of cyanocobalamin for 24 h, its content in their leaves increased significantly from nondetectable to 164.6 ± 74.7 ng/g fresh weight. This finding indicated that consumption of only two or three of these fresh leaves is sufficient to meet the Recommended Dietary Allowance for adults of 2.4 μg/day. Analyses using a cobalamin-dependent Escherichia coli 215 bioautogram and LC/ESI-MS/MS demonstrated that the cyanocobalamin absorbed from the nutrient solutions by the leaves did not alter any other compounds such as coenzymes and inactive corrinoids. Gel filtration indicated that most (86%) of the cyanocobalamin in the leaves was recovered in the free cyanocobalamin fractions. These results indicated that cyanocobalamin-enriched lettuce leaves would be an excellent source of free cyanocobalamin, particularly for strict vegetarians or elderly people with food-bound cobalamin malabsorption.

  5. High Phenolics Rutgers Scarlet Lettuce Improves Glucose Metabolism in High Fat Diet-Induced Obese Mice

    Science.gov (United States)

    Cheng, Diana M.; Roopchand, Diana E.; Poulev, Alexander; Kuhn, Peter; Armas, Isabel; Johnson, William D.; Oren, Andrew; Ribnicky, David; Zelzion, Ehud; Bhattacharya, Debashish; Raskin, Ilya

    2016-01-01

    Scope The ability of high phenolic Rutgers Scarlet Lettuce (RSL) to attenuate metabolic syndrome and gut dysbiosis was studied in very high fat diet (VHFD)-fed mice. Phenolic absorption was assessed in vivo and in a gastrointestinal tract model. Methods and results Mice were fed VHFD, VHFD supplemented with RSL (RSL-VHFD) or store-purchased green lettuce (GL-VHFD), or low-fat diet (LFD) for 13 weeks. Compared to VHFD or GL-VHFD-fed groups, RSL-VHFD group showed significantly improved oral glucose tolerance (p<0.05). Comparison of VHFD, RSL-VHFD, and GL-VHFD groups revealed no significant differences with respect to insulin tolerance, hepatic lipids, body weight gain, fat mass, plasma glucose, triglycerides, free fatty acid, and lipopolysaccharide levels, as well as relative abundances of major bacterial phyla from 16S rDNA amplicon data sequences (from fecal and cecal samples). However, RSL and GL-supplementation increased abundance of several taxa involved in plant polysaccharide degradation/fermentation. RSL phenolics chlorogenic acid, quercetin-3-glucoside, and quercetin-malonyl-glucoside were bioaccessible in the TIM-1 digestion model, but had relatively low recovery. Conclusions RSL phenolics contributed to attenuation of postprandial hyperglycemia. Changes in gut microbiota were likely due to microbiota accessible carbohydrates in RSL and GL rather than RSL phenolics, which may be metabolized, absorbed, or degraded before reaching the colon. PMID:27529448

  6. The Effect of Anaerobic and Aerobic Fish Sludge Supernatant on Hydroponic Lettuce

    Directory of Open Access Journals (Sweden)

    Simon Goddek

    2016-06-01

    Full Text Available The mobilization of nutrients from fish sludge (i.e., feces and uneaten feed plays a key role in optimizing the resource utilization and thus in improving the sustainability of aquaponic systems. While several studies have documented the aerobic and anaerobic digestion performance of aquaculture sludge, the impact of the digestate on plant growth has yet to be understood. The present study examines the impact of either an aerobic or an anaerobic digestion effluent on lettuce plant growth, by enriching a mixture of aquaculture and tap water with supernatants from both aerobic and anaerobic batch reactors. The lettuce plants grown in the hydroponic system supplied with supernatant from an anaerobic reactor had significantly better performance with respect to weight gain than both, those in the system where supernatant from the aerobic reactor was added, as well as the control system. It can be hypothesized that this effect was caused by the presence of NH4+ as well as dissolved organic matter, plant growth promoting rhizobacteria and fungi, and humic acid, which are predominantly present in anaerobic effluents. This study should therefore be of value to researchers and practitioners wishing to further develop sludge remineralization in aquaponic systems.

  7. Effect of phenol on germination capacity and polyphenol oxidase, peroxidase and catalase activities in lettuce

    Directory of Open Access Journals (Sweden)

    Tadić Vojin

    2014-01-01

    Full Text Available In this study we examined the activities of polyphenol oxidase (PPO and antioxidant enzymes, peroxidase (POX and catalase (CAT during lettuce seed germination at different concentrations of phenol. Out of eleven varieties of lettuce, four were chosen according to their germination tolerance to phenol as follows: plants exhibiting high (Ljubljanska ledenka - LJL and Nansen - N and low toleranace (Little Gem - LG and Majska kraljica - MK. A decrease in germination efficiency after exposure to LD50 of phenol was determined for these four varieties. The effects of phenol treatment on POX, CAT and PPO activities were determined after 4, 5, 6, 7 and 8 days of growth at LD50 concentrations. A trend of increased peroxidase activity was observed in seeds grown on LD50 of phenol compared to control seeds. A significant increase in CAT activity was observed at the beginning of treatment for MK, LG and N in seeds grown on phenol as well as in control seeds. A trend of increased PPO activity was observed in all control seeds. We also investigated the affinity of PPO for two different substrates that were used for the determination of enzyme activity. Our results show that LJL and N are the varieties most tolerant to growth on phenol. Here we report on the activities of their antioxidant enzymes and PPO during seed germination. [Projekat Ministarstva nauke Republike Srbije, br. ON173017

  8. Physiological responses of seeds and seedlings of lettuce submitted to Philodendron bipinnatifidum extract

    Directory of Open Access Journals (Sweden)

    Tiago Zanatta Aumonde

    2013-12-01

    Full Text Available The work was conducted to evaluate the effect of different Philodendron bipinnatifidum Schott. extract concentrations on the physiology and enzymatic metabolism of lettuce seeds and seedlings. The treatments extracts of mature leaves at concentrations of 0, 6, 12, 25 and 50%. Were evaluated the germination, first count germination, speed and germination speed index, length of shoot and primary root, seedling total dry mass, electrical conductivity, chlorophyll content, activity of the enzymes ?-amilase, superoxide dismutase, catalase and ascorbarto peroxidase, lipid peroxidation, hydrogen peroxide content and seedling emergence, length of shoot and total dry mass of emerged seedlings. There was a reduction of germination, germination speed index and total dry mass by increasing the concentration of the extract. While the content of hydrogen peroxide, lipid peroxidation and activity of superoxide dismutase, catalase and peroxidase ascorbarto increased with concentration. The increasing of concentration the leaf extracts of the P. bipinnatifidum negatively affects the activity of the enzyme ?-amylase and causes increase in the activity of antioxidant enzymes, affecting the physiologic performance and growth of lettuce seedlings.

  9. The metabolism and distribution of 14C-8N6-benzyladenine in lettuce seeds and seedlings

    International Nuclear Information System (INIS)

    Seeber, R.G. Jr.

    1989-01-01

    This investigation sought to follow the uptake of the cytokinin, 14 C-8N 6 -benzyladenine (BAP), by lettuce seeds through time, trace the movement of the metabolites through several areas of the seedling, and identify the BAP metabolites. Lettuce seeds (Lactuca sativa L. cv. Grand Rapids) were exposed to a two hour pulse of the radioactive BAP. These seeds were harvested at 4 hour intervals from 2-48 hours. Seedlings incubated from 36-48 hours were cut in two; root, stem, shoot tip and seed coats. Each of these groups were extracted in 70% methanol and their radioactive isolated by high performance liquid chromatography. Radioactive fractions were pooled and reduced for further analysis by thin layer chromatography. The major compound identified throughout the time periods was BAP, exclusively found from 2-20 hours. BAP riboside was found in addition to BAP from 24-32 hours. The 40 and 44 hour extracts contained BAP and its riboside in the shoot and BAP in the seed coat. The 48 hours extract contained BAP and its riboside in both the shoot tip and the seed coat. This study produced information on the following points. A cytokinin exposure of 2 hours or less is needed to break dormancy in these seeds

  10. Biotic Stress Shifted Structure and Abundance of Enterobacteriaceae in the Lettuce Microbiome

    Science.gov (United States)

    Erlacher, Armin; Cardinale, Massimiliano; Grube, Martin; Berg, Gabriele

    2015-01-01

    Lettuce cultivars are not only amongst the most popular vegetables eaten raw, they are also involved in severe pathogen outbreaks world-wide. While outbreaks caused by Enterobacteriaceae species are well-studied, less is known about their occurrence in natural environments as well as the impact of biotic stress. Here, we studied the ecology of the human health-relevant bacterial family Enterobacteriaceae and assessed the impact of biotic disturbances by a soil-borne phytopathogenic fungus and Gastropoda on their structure and abundance in mesocosm and pot experiments. Using a polyphasic approach including network analyses of 16S rRNA gene amplicon libraries, quantitative PCR and complementary fluorescence in situ hybridization (FISH) microscopy we found substantial yet divergent Enterobacteriaceae communities. A similar spectrum of 14 genera was identified from rhizo- and phyllospheres but the abundance of Enterobacteriaceae was on average 3fold higher in phyllosphere samples. Both stress factors shifted the bacterial community of the leaf habitat, characterized by increases of species abundance and diversity. For the rhizosphere, we observed significant structural shifts of Enterobacteriaceae communities but also a high degree of resilience. These results could be confirmed by FISH microscopy but it was difficult to visualize phyllosphere communities. Additional inoculation experiments with Escherichia coli as model revealed their presence below the wax layer as well as in the endosphere of leaves. The observed presence influenced by stress factors and the endophytic life style of Enterobacteriaceae on lettuce can be an important aspect in relation to human health. PMID:25714833

  11. Prediction of rate of CO2 assimilation of leaf lettuce under low light irradiation during storage

    International Nuclear Information System (INIS)

    Uchino, T.; Harada, F.; Hu, W.

    2003-01-01

    The rate of CO 2 assimilation of leaf lettuce changed with its respiration rate and gas constitution in a storage chamber. The optimum irradiance on the surface of leaf lettuce during storage using low light irradiation can be obtained by the prediction of the rate of CO 2 assimilation. For the above mentioned purpose the following equation were derived. -kd[C]/dt=0.5(1-f)I([C]-Γ/4.5[C]+10.5Γ)-ae -bt where, k: proportional constant (4.87×10 -3 mol⋅m -2 ) [C]: CO 2 concentration (ppm), t: time (h), f: fraction of light not absorbed by chloroplasts (0.23), I: irradiance (μmol⋅m-2⋅s -1 ), Γ: CO 2 compensation point without respiration (21.5ppm), a, b: parameters (0.308μmol⋅m -2 ⋅s -1 , 0.010h -1 ). Calculated values of rate of CO 2 assimilation by the equation agreed well with experimental ones at 3.4 and 6.5μmol⋅m -2 ⋅s -1 of irradiance, so it appeared that the assimilation rate could be sufficiently predicted

  12. Soil-plant transfer factors of Co-60 for alfalfa lettuce and spinach

    International Nuclear Information System (INIS)

    Dumitru, Radu Octavian

    1997-01-01

    The transfer of Co-60 from soil into plants is a less studied problem. Soil-plant transfer factors for Co-60 known from literature vary by about four orders of magnitude for each kind of plants. We have calculated the average values and have determined the field of variability of the known transfer factors. These indicated us that alfalfa, lettuce and spinach have in this order the greatest absorption capacity of Co-60 from soil. We have determined the physical, chemical and mineralogical properties of the utilized soil. This is a brown reddish forest type soil. The plants have been cultivated in pots by plantlet method of Neubauer and Schneider. The results of our measurements of soil-to-plant transfer factors of 60-Co are the followings: 0.0612 ± 0.0047 for alfalfa, 0.0960 ± 0.0072 for lettuce and 0.1446 ± 0.0107 for spinach. These values prove the strong dependence of the type of soil and plant of the soil-plant transfer factors for Co-60. (author)

  13. On hybridising lettuce seedlings with nanoparticles and the resultant effects on the organisms' electrical characteristics.

    Science.gov (United States)

    Gizzie, Nina; Mayne, Richard; Patton, David; Kendrick, Paul; Adamatzky, Andrew

    2016-09-01

    Lettuce seedlings are attracting interest in the computing world due to their capacity to become hybrid circuit components, more specifically, in the creation of living 'wires'. Previous studies have shown that seedlings can be hybridised with gold nanoparticles and withstand mild electrical currents. In this study, lettuce seedlings were hybridised with a variety of metallic and non-metallic nanomaterials: carbon nanotubes, graphene oxide, aluminium oxide and calcium phosphate. Toxic effects and the following electrical properties were monitored: mean potential, resistance and capacitance. Macroscopic observations revealed only slight deleterious health effects after administration with one variety of particle, aluminium oxide. Mean potential in calcium phosphate-hybridised seedlings showed a considerable increase when compared with the control, whereas those administered with graphene oxide showed a small decrease; there were no notable variations across the remaining treatments. Electrical resistance decreased substantially in graphene oxide-treated seedlings whereas slight increases were shown following calcium phosphate and carbon nanotubes applications. Capacitance showed no considerable variation across treated seedlings. These results demonstrate that use of some nanomaterials, specifically graphene oxide and calcium phosphate, may be towards biohybridisation purposes including the generation of living 'wires'. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  14. Existence of vigorous lineages of crop-wild hybrids in Lettuce under field conditions.

    Science.gov (United States)

    Hooftman, Danny A P; Hartman, Yorike; Oostermeijer, J Gerard B; Den Nijs, Hans J C M

    2009-01-01

    Plant to plant gene flow is a route of environmental exposure for GM plants specifically since crosses with wild relatives could lead to the formation of more vigorous hybrids, which could increase the rate of introgression and the environmental impact. Here, we test the first step in the process of potential transgene introgression: whether hybrid vigor can be inherited to the next generation, which could lead to fixation of altered, i.e., elevated, quantitative traits. The potential for a permanent elevated fitness was tested using individual autogamous progeny lineages of hybrids between the crop Lactuca sativa (Lettuce) and the wild species Lactuca serriola (Prickly Lettuce). We compared progeny from motherplants grown under either greenhouse or field conditions. The survival of young plants depended strongly on maternal environment. Furthermore, we observed that offspring reproductive fitness components were correlated with maternal fitness. Our study demonstrates that post-zygotic genotypic sorting at the young plants stage reduces the number of genotypes non-randomly, leading to inheritance of high levels of reproductive traits in the surviving hybrid lineages, compared to the pure wild relatives. Consequently, directional selection could lead to displacement of the pure wild relative and fixation of more vigorous genome segments originating from crops, stabilizing plant traits at elevated levels. Such information can be used to indentify segments which are less likely to introgress into wild relative populations as a target for transgene insertion. © ISBR, EDP Sciences, 2010.

  15. Rin4 causes hybrid necrosis and race-specific resistance in an interspecific lettuce hybrid.

    Science.gov (United States)

    Jeuken, Marieke J W; Zhang, Ningwen W; McHale, Leah K; Pelgrom, Koen; den Boer, Erik; Lindhout, Pim; Michelmore, Richard W; Visser, Richard G F; Niks, Rients E

    2009-10-01

    Some inter- and intraspecific crosses may result in reduced viability or sterility in the offspring, often due to genetic incompatibilities resulting from interactions between two or more loci. Hybrid necrosis is a postzygotic genetic incompatibility that is phenotypically manifested as necrotic lesions on the plant. We observed hybrid necrosis in interspecific lettuce (Lactuca sativa and Lactuca saligna) hybrids that correlated with resistance to downy mildew. Segregation analysis revealed a specific allelic combination at two interacting loci to be responsible. The allelic interaction had two consequences: (1) a quantitative temperature-dependent autoimmunity reaction leading to necrotic lesions, lethality, and quantitative resistance to an otherwise virulent race of Bremia lactucae; and (2) a qualitative temperature-independent race-specific resistance to an avirulent race of B. lactucae. We demonstrated by transient expression and silencing experiments that one of the two interacting genes was Rin4. In Arabidopsis thaliana, RIN4 is known to interact with multiple R gene products, and their interactions result in hypersensitive resistance to Pseudomonas syringae. Site-directed mutation studies on the necrosis-eliciting allele of Rin4 in lettuce showed that three residues were critical for hybrid necrosis.

  16. Biotic stress shifted structure and abundance of Enterobacteriaceae in the lettuce microbiome.

    Science.gov (United States)

    Erlacher, Armin; Cardinale, Massimiliano; Grube, Martin; Berg, Gabriele

    2015-01-01

    Lettuce cultivars are not only amongst the most popular vegetables eaten raw, they are also involved in severe pathogen outbreaks world-wide. While outbreaks caused by Enterobacteriaceae species are well-studied, less is known about their occurrence in natural environments as well as the impact of biotic stress. Here, we studied the ecology of the human health-relevant bacterial family Enterobacteriaceae and assessed the impact of biotic disturbances by a soil-borne phytopathogenic fungus and Gastropoda on their structure and abundance in mesocosm and pot experiments. Using a polyphasic approach including network analyses of 16S rRNA gene amplicon libraries, quantitative PCR and complementary fluorescence in situ hybridization (FISH) microscopy we found substantial yet divergent Enterobacteriaceae communities. A similar spectrum of 14 genera was identified from rhizo- and phyllospheres but the abundance of Enterobacteriaceae was on average 3fold higher in phyllosphere samples. Both stress factors shifted the bacterial community of the leaf habitat, characterized by increases of species abundance and diversity. For the rhizosphere, we observed significant structural shifts of Enterobacteriaceae communities but also a high degree of resilience. These results could be confirmed by FISH microscopy but it was difficult to visualize phyllosphere communities. Additional inoculation experiments with Escherichia coli as model revealed their presence below the wax layer as well as in the endosphere of leaves. The observed presence influenced by stress factors and the endophytic life style of Enterobacteriaceae on lettuce can be an important aspect in relation to human health.

  17. Biotic stress shifted structure and abundance of Enterobacteriaceae in the lettuce microbiome.

    Directory of Open Access Journals (Sweden)

    Armin Erlacher

    Full Text Available Lettuce cultivars are not only amongst the most popular vegetables eaten raw, they are also involved in severe pathogen outbreaks world-wide. While outbreaks caused by Enterobacteriaceae species are well-studied, less is known about their occurrence in natural environments as well as the impact of biotic stress. Here, we studied the ecology of the human health-relevant bacterial family Enterobacteriaceae and assessed the impact of biotic disturbances by a soil-borne phytopathogenic fungus and Gastropoda on their structure and abundance in mesocosm and pot experiments. Using a polyphasic approach including network analyses of 16S rRNA gene amplicon libraries, quantitative PCR and complementary fluorescence in situ hybridization (FISH microscopy we found substantial yet divergent Enterobacteriaceae communities. A similar spectrum of 14 genera was identified from rhizo- and phyllospheres but the abundance of Enterobacteriaceae was on average 3fold higher in phyllosphere samples. Both stress factors shifted the bacterial community of the leaf habitat, characterized by increases of species abundance and diversity. For the rhizosphere, we observed significant structural shifts of Enterobacteriaceae communities but also a high degree of resilience. These results could be confirmed by FISH microscopy but it was difficult to visualize phyllosphere communities. Additional inoculation experiments with Escherichia coli as model revealed their presence below the wax layer as well as in the endosphere of leaves. The observed presence influenced by stress factors and the endophytic life style of Enterobacteriaceae on lettuce can be an important aspect in relation to human health.

  18. Abscisic acid in the thermoinhibition of lettuce seed germination and enhancement of its catabolism by gibberellin.

    Science.gov (United States)

    Gonai, Takeru; Kawahara, Shusuke; Tougou, Makoto; Satoh, Shigeru; Hashiba, Teruyoshi; Hirai, Nobuhiro; Kawaide, Hiroshi; Kamiya, Yuji; Yoshioka, Toshihito

    2004-01-01

    Germination of lettuce (Lactuca sativa L. cv. 'Grand Rapids') seeds was inhibited at high temperatures (thermoinhibition). Thermoinhibition at 28 degrees C was prevented by the application of fluridone, an inhibitor of abscisic acid (ABA) biosynthesis. At 33 degrees C, the sensitivity of the seeds to ABA increased, and fluridone on its own was no longer effective. However, a combined application of fluridone and gibberellic acid (GA3) was able to restore the germination. Exogenous GA3 lowered endogenous ABA content in the seeds, enhancing catabolism of ABA and export of the catabolites from the intact seeds. The fluridone application also decreased the ABA content. Consequently, the combined application of fluridone and GA3 decreased the ABA content to a sufficiently low level to allow germination at 33 degrees C. There was no significant temperature-dependent change in endogenous GA1 contents. It is concluded that ABA is an important factor in the regulation of thermoinhibition of lettuce seed germination, and that GA affects the temperature responsiveness of the seeds through ABA metabolism.

  19. Secondary metabolism and antioxidants are involved in environmental adaptation and stress tolerance in lettuce.

    Science.gov (United States)

    Oh, Myung-Min; Trick, Harold N; Rajashekar, C B

    2009-01-30

    Lettuce (Lactuca sativa) plants grown in a protective environment, similar to in vitro conditions, were acclimated in a growth chamber and subjected to water stress to examine the activation of genes involved in secondary metabolism and biosynthesis of antioxidants. The expression of phenylalanine ammonia-lyase (PAL), gamma-tocopherol methyl transferase (gamma-TMT) and l-galactose dehydrogenase (l-GalDH) genes involved in the biosynthesis of phenolic compounds, alpha-tocopherol and ascorbic acid, respectively, were determined during plant adaptation. These genes were activated in tender plants, grown under protective conditions, when exposed to normal growing conditions in a growth chamber. A large increase in transcript level for PAL, a key gene in the phenylpropanoid pathway leading to the biosynthesis of a wide array of phenolics and flavonoids, was observed within 1h of exposure of tender plants to normal growing conditions. Plant growth, especially the roots, was retarded in tender plants when exposed to normal growing conditions. Furthermore, exposure of both protected and unprotected plants to water stress resulted in the activation of PAL. PAL inhibition by 2-aminoindan-2-phosphonic acid (AIP) rendered these plants more sensitive to chilling and heat shock treatments. These results suggest that activation of secondary metabolism as well as the antioxidative metabolism is an integral part of plant adaptation to normal growing conditions in lettuce plants.

  20. Methodology for determination of benzimidazolic fungicides residues in strawberry and lettuce by HPLC-DAD

    International Nuclear Information System (INIS)

    Dangond Araujo, Jose Jairo; Guerrero dallos, Jairo Arturo

    2006-01-01

    systemic fungicides like benzimidazolic compounds are used to protect several crops of fruits and vegetables. in this work a new method for analysis of Benomyl, carbendazim and thiabendazol in strawberry and lettuce by high performance liquid chromatography with diode array detector (HPLC-DAD) was validated. benomyl residues were determined after its conversion to carbendazim. pesticide residues were extracted from strawberry and lettuce samples with ethyl acetate and these extracts were cleaned up by gel permeation chromatography (GPC). final determination was carried out by HPLC-DAD in reverse phase column. the method is selective, specific, precise and accurate. the calibration curves show linearity over concentration range of 1.24 to 6.19 mg/kg, with detection limits of 0.40 and 0.27 mg/kg and quantification limits of 1.35 and 0.81 mg/kg for carbendazim and thiabendazole respectively. the recovery experiments yielding averages of 90 %. n o residues of these compounds were found in collected samples from specific areas of Cundinamarca, Colombia