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Sample records for water lettuce duckweed

  1. Removal of chlorpyrifos by water lettuce (Pistia stratiotes L.) and duckweed (Lemna minor L.).

    Science.gov (United States)

    Prasertsup, Pichamon; Ariyakanon, Naiyanan

    2011-04-01

    The potential of water lettuce (Pistia stratiotes L.) and duckweed (Lemna minor L.) to remove chlorpyrifos in water was investigated under laboratory greenhouse conditions. At initial chlorpyrifos concentrations of 0.0, 0.1 and 0.5 mg/L, the relative growth rates (RGR) of L. minor and P. stratiotes were not significantly different. In contrast, in the presence of 1 mg/L chlorpyrifos the RGR was significantly inhibited, giving an observed fresh weight based RGR(FW) for P. stratiotes and L. minor from day 0 to 7 of -0.036 and -0.023 mg/g/day, respectively. The maximum removal of chlorpyrifos by P. stratiotes and L. minor, when chlorpyrifos was at an initial culture concentration of 0.5 mg/L, was 82% and 87%, respectively, with disappearance rate constants under these conditions of 2.94, 10.21 and 12.14 microg h(-1) for the control (no plants), and with P. stratiotes and L. minor, respectively, giving actual corrected plant removal rate constants of 7.27 and 9.20 microg h(-1) for P. stratiotes and L. minor, respectively. The bioconcentration factor (BCF) of L. minor was significantly greater than that for P. stratiotes and therefore, at least under these greenhouse-based conditions, L. minor was more efficient than P. stratiotes for the accelerated removal of chlorpyrifos from water. PMID:21598800

  2. Comparative performance studies of water lettuce, duckweed, and algal-based stabilization ponds using low-strength sewage.

    Science.gov (United States)

    Awuah, Esi; Oppong-Peprah, M; Lubberding, H J; Gijzen, H J

    A bench-scale continuous-flow wastewater treatment system comprising three parallel lines using duckweed (Spirodela polyrhiza), water lettuce (Pistia stratiotes), and algae (natural colonization) as treatment agents was set up to determine environmental conditions, fecal coliform profiles and general treatment performance. Each line consisted of four ponds connected in series fed by diluted sewage. Influent and effluent parameters measured included environmental conditions, turbidity, biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate, nitrite, ammonia, total phosphorus, fecal coliforms, mosquito larvae, and sludge accumulations. Environmental conditions and fecal coliforms profiles were determined in the sediments (0.63 m), suspensions (0.35 m), and surfaces (0.1 m) of each pond. Acidic conditions were observed in the pistia ponds, neutral conditions in duckweed ponds, and alkaline conditions in algal ponds. Fecal coliforms log removals of 6, 4, and 3 were observed in algal, duckweed, and pistia ponds, respectively, in the final effluents, with die-off rates per pond of 2.7, 2.0, and 1.6. Sedimentation accounted for over 99% fecal coliform removal in most of the algal and pistia ponds. BOD removal was highest in the duckweed system, followed by pistia and algae at 95%, 93%, and 25%, respectively. COD removals were 65% and 59%, respectively, for duckweed and pistia, while COD increased in algal ponds by 56%. Nitrate removals were 72%, 70%, and 36%, respectively for duckweed, pistia, and algal ponds. Total phosphorus removals were 33% and 9% for pistia and duckweed systems, while an increase of 19% was observed in the algal treatment system. Ammonia removals were 95% in both pistia and duckweed and 93% in algal systems. Removals of total dissolved solids (TDS) were 70% for pistia, 15% for duckweed, and 9% for algae. Mosquito populations of 11,175/m(2), 3516/m(2), and 96/m(2) were counted in pistia, algal, and duckweed ponds, respectively. Low turbidity and low sludge accumulation characterized the macrophyte ponds. Performance in the removal of fecal coliforms in the algal-based treatment system and organic load removal in both macrophytes and algal-based treatment systems met the Ghana Environmental Protection Agency guideline values. PMID:15371212

  3. Differences in the availabilities of cesium-134,137 and ruthenium-106 from a Chernobyl-contaminated soil to a water plant, duckweed, and to the terrestrial plants, bean and lettuce

    International Nuclear Information System (INIS)

    The aqueous solubilities of some radionuclides present in a Chernobyl-contaminated soil and their subsequent availabilities to an aquatic plant, duckweed (Lemnaceae), were compared to those obtained for bean (Phaseolus vulgaris) and lettuce (Lactuca sativa). During this investigation carried out in laboratory conditions, it was observed that, although around 0.06% of 134Cs or 137Cs present in the soil was detected in the aqueous phase, duckweed concentrated 1000-5500 times this amount, depending on plant species. By contrast, 106Ru in the soil was leached more effectively into solution than was cesium but its accumulation into duckweed was less. The effects on the availabilities of ruthenium and cesium of depletion of soil organic matter and of amendment of the aqueous phase with nutrients were also investigated. The transfer factors of 134,137Cs into bean and lettuce cultivated in the same soil were 0.02 and 0.06, respectively, while that for 106Ru was around 0.2. The difference between aquatic and terrestrial plants in cycling radionuclides is briefly discussed. (author)

  4. Diminished mercury emission from waters with duckweed cover

    Science.gov (United States)

    Wollenberg, Jennifer L.; Peters, Stephen C.

    2009-06-01

    Duckweeds (Lemnaceae) are a widely distributed type of floating vegetation in freshwater systems. Under suitable conditions, duckweeds form a dense vegetative mat on the water surface, which reduces light penetration into the water column and limits gas exchange at the water-air interface by decreasing the area of open water surface. Experiments were conducted to determine whether duckweed decreases mercury emission by limiting gas diffusion across the water-air interface and attenuating light, or, conversely, enhances emission via transpiration of mercury vapor. Microcosm flux chamber experiments indicate that duckweed decreases mercury emission from the water surface compared to open water controls. Fluxes under duckweed were 17-67% lower than in controls, with lower fluxes occurring at higher percent cover. The decrease in mercury emission suggests that duckweed may limit emission through one of several mechanisms, including limited gas transport across the air-water interface, decreased photoreactions due to light attenuation, and plant-mercury interactions. The results of this experiment were applied to a model lake system to illustrate the magnitude of potential effects on mercury cycling. The mercury retained in the lake as a result of hindered emission may increase bioaccumulation potential in lakes with duckweed cover.

  5. Diminished Mercury Emission From Water Surfaces by Duckweed (Lemna minor)

    Science.gov (United States)

    Wollenberg, J. L.; Peters, S. C.

    2007-12-01

    Aquatic plants of the family Lemnaceae (generally referred to as duckweeds) are a widely distributed type of floating vegetation in freshwater systems. Under suitable conditions, duckweeds form a dense vegetative mat on the water surface, which reduces light penetration into the water column and decreases the amount of exposed water surface. These two factors would be expected to reduce mercury emission by limiting a) direct photoreduction of Hg(II), b) indirect reduction via coupled DOC photooxidation-Hg(II) reduction, and c) gas diffusion across the water-air interface. Conversely, previous studies have demonstrated transpiration of Hg(0) by plants, so it is therefore possible that the floating vegetative mat would enhance emission via transpiration of mercury vapor. The purpose of this experiment was to determine whether duckweed limits mercury flux to the atmosphere by shading and the formation of a physical barrier to diffusion, or whether it enhances emission from aquatic systems via transpiration of Hg(0). Deionized water was amended with mercury to achieve a final concentration of approximately 35 ng/L and allowed to equilibrate prior to the experiment. Experiments were conducted in rectangular polystyrene flux chambers with measured UV-B transmittance greater than 60% (spectral cutoff approximately 290 nm). Light was able to penetrate the flux chamber from the sides as well as the top throughout the experiment, limiting the effect of shading by duckweed on the water surface. Flux chambers contained 8L of water with varying percent duckweed cover, and perforated plastic sheeting was used as an abiotic control. Exposures were conducted outside on days with little to no cloud cover. Real time mercury flux was measured using atomic absorption (Mercury Instruments UT-3000). Total solar and ultraviolet radiation, as well as a suite of meteorological parameters, were also measured. Results indicate that duckweed diminishes mercury emission from the water surface as compared to open water controls. Decreases in emission rate varied linearly with percent duckweed cover, with lower fluxes occurring at higher percent cover. Mercury flux in the duckweed treatments as compared to open water treatments decreased from 17% in the lowest percent cover treatment to 67% in the highest percent cover treatment. The observed decrease in mercury emission suggests that duckweed limits emission via the formation of a physical barrier to diffusion.

  6. Decontamination of lettuce using acidic electrolyzed water.

    Science.gov (United States)

    Koseki, S; Yoshida, K; Isobe, S; Itoh, K

    2001-05-01

    The disinfectant effect of acidic electrolyzed water (AcEW), ozonated water, and sodium hypochlorite (NaOCl) solution on lettuce was examined. AcEW (pH 2.6; oxidation reduction potential, 1140 mV; 30 ppm of available chlorine) and NaOCl solution (150 ppm of available chlorine) reduced viable aerobes in lettuce by 2 log CFU/g within 10 min. For lettuce washed in alkaline electrolyzed water (AIEW) for 1 min and then disinfected in AcEW for 1 min, viable aerobes were reduced by 2 log CFU/g. On the other hand, ozonated water containing 5 ppm of ozone reduced viable aerobes in lettuce 1.5 log CFU/g within 10 min. It was discovered that AcEW showed a higher disinfectant effect than did ozonated water significantly at P ozonated water, and NaOCI solution removed aerobic bacteria, coliform bacteria, molds, and yeasts on the surface of lettuce. Therefore, residual microorganisms after the decontamination of lettuce were either in the inside of the cellular tissue, such as the stomata, or making biofilm on the surface of lettuce. Biofilms were observed by a scanning electron microscope on the surface of the lettuce treated with AcEW. Moreover, it was shown that the spores of bacteria on the surface were not removed by any treatment in this study. However, it was also observed that the surface structure of lettuce was not damaged by any treatment in this study. Thus, the use of AcEW for decontamination of fresh lettuce was suggested to be an effective means of controlling microorganisms. PMID:11347995

  7. Suitability of Using Duckweed as Feed and Treated Sewage as Water Source in Tilapia Aquaculture

    International Nuclear Information System (INIS)

    Use of treated effluent and duckweed biomass from a pilot-scale UASB-duckweed ponds system treating domestic sewage was evaluated in rearing Nile tilapia (Oreochromis niloticus). Nutritional value of duckweed as sole feed was compared with wheat bran. Two sources of water were used for each feed trial, treated-sewage and freshwater. The experiment was conducted in parallel with a conventional settled sewage-fed fishpond. Results of growth performance demonstrated that, in case of freshwater ponds specific growth rate (SGR) of tilapia fed on fresh duckweed was significantly (p 0.05) was observed between the two feeding regimes in treated sewage fed ponds. The SGR of tilapia reared in the treated sewage-wheat bran-fed pond (TWP) was significant higher (p <0.01) than the SGR in the freshwater-wheat bran-fed pond (FWP). On the other hand, due to the early spawning in the treated sewage-duckweed fed pond (TOP) SGR of tilapia in the latter was significantly lower (p <0.05) than the SGR in the freshwater-duckweed-fed pond (FDP). The results of net fish yield were 11.8, 8.9, 9.6 and 6.4 ton/ha/y in TDP, TWP, FDP and FWP, respectively. negative net yield (-0.16 ton/ha/y) was observed in the settled sewage- fed pond (SSP) due to high mortality

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

    OpenAIRE

    Claudinei Fonseca Souza; Simone Sano Rossi de Rezende; Joseane Marioto de Souza; Antonio Claudio Testa Varallo

    2011-01-01

    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, ...

  9. Catalytic upgrading of duckweed biocrude in subcritical water.

    Science.gov (United States)

    Zhang, Caicai; Duan, Peigao; Xu, Yuping; Wang, Bing; Wang, Feng; Zhang, Lei

    2014-08-01

    Herein, a duckweed biocrude produced from the hydrothermal liquefaction of Lemna minor was treated in subcritical water with added H?. Effects of several different commercially available materials such as Ru/C, Pd/C, Pt/C, Pt/?-Al?O?, Pt/C-sulfide, Rh/?-Al?O?, activated carbon, MoS?, Mo?C, Co-Mo/?-Al?O?, and zeolite on the yields of product fractions and the deoxygenation, denitrogenation, and desulfurization of biocrude at 350°C were examined, respectively. All the materials showed catalytic activity for deoxygenation and desulfurization of the biocrude and only Ru/C showed activity for denitrogenation. Of those catalysts examined, Pt/C showed the best performance for deoxygenation. Among all the upgraded oils, the oil produced with Ru/C shows the lowest sulfur, the highest hydrocarbon content (25.6%), the highest energy recovery (85.5%), and the highest higher heating value (42.6 MJ/kg). The gaseous products were mainly unreacted H?, CH?, CO?, and C?H6. PMID:24880811

  10. Modelling Ontogenetic Changes of Nitrogen and Water Content in Lettuce

    OpenAIRE

    SEGINER, IDO; BLEYAERT, PETER; BREUGELMANS, MAAIKE

    2004-01-01

    • Background and Aims It is well established that the nitrogen content of plants, including lettuce, decreases with time. It has also been observed that water content of lettuce increases between planting and harvest. This paper is an attempt at modelling these observations.

  11. 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.

  12. Potential of duckweed in the conversion of wastewater nutrients to valuable biomass: a pilot-scale comparison with water hyacinth.

    Science.gov (United States)

    Zhao, Yonggui; Fang, Yang; Jin, Yanling; Huang, Jun; Bao, Shu; Fu, Tian; He, Zhiming; Wang, Feng; Zhao, Hai

    2014-07-01

    The application potential of duckweed (Lemna japonica 0234) and water hyacinth (Eichhornia crassipes) were compared in two pilot-scale wastewater treatment systems for more than one year. The results indicated duckweed had the same total nitrogen (TN) recovery rate as water hyacinth (0.4 g/m(2)/d) and a slightly lower total phosphorus (TP) recovery rate (approximately 0.1g/m(2)/d) even though its biomass production was half that of water hyacinth. The higher content of crude protein (33.34%), amino acids (25.80%), starch (40.19%), phosphorus (1.24%), flavonoids (2.91%) and lower fiber content provided duckweed with more advantages in resource utilization. Additionally, microbial community discovered by 454 pyrosequencing indicated that less nitrifying bacteria and more nitrogen-fixing bacteria in rhizosphere of duckweed provided it with higher nitrogen recovery efficiency (60%) than water hyacinth (47%). Under the presented condition, duckweed has more application advantages than water hyacinth because it more effectively converted the wastewater nutrients into valuable biomass. PMID:24787320

  13. DUCKWEED – A PERSPECTIVE VEGETABLE PLANT

    Directory of Open Access Journals (Sweden)

    Tsatsenko L. V.

    2014-10-01

    Full Text Available The questions of use duckweed as green vegetable are considered in article. The structure of types of duckweeds, their biological features, distribution in the world and in the territory of the Krasnodar region is shown. Possibility of their use as biotesters and bioindicators of the water environment, as analytical system for the analysis is shown. Questions of use of duckweed in artificial conditions as well as requirements to the content of culture are considered

  14. Comparative Analysis of Duckweed Cultivation with Sewage Water and SH Media for Production of Fuel Ethanol

    OpenAIRE

    Yu, Changjiang; Sun, Changjiang; Yu, Li; Zhu, Ming; XU Hua; Zhao, Jinshan; Ma, Yubin; Zhou, Gongke

    2014-01-01

    Energy crises and environmental pollution have caused considerable concerns; duckweed is considered to be a promising new energy plant that may relieve such problems. Lemna aequinoctialis strain 6000, which has a fast growth rate and the ability to accumulate high levels of starch was grown in both Schenk & Hildebrandt medium (SH) and in sewage water (SW). The maximum growth rates reached 10.0 g DW m?2 day?1 and 4.3 g DW m?2 day?1, respectively, for the SH and SW cultures, while the starch co...

  15. Comparative Analysis of Duckweed Cultivation with Sewage Water and SH Media for Production of Fuel Ethanol

    Science.gov (United States)

    Yu, Li; Zhu, Ming; Xu, Hua; Zhao, Jinshan; Ma, Yubin; Zhou, Gongke

    2014-01-01

    Energy crises and environmental pollution have caused considerable concerns; duckweed is considered to be a promising new energy plant that may relieve such problems. Lemna aequinoctialis strain 6000, which has a fast growth rate and the ability to accumulate high levels of starch was grown in both Schenk & Hildebrandt medium (SH) and in sewage water (SW). The maximum growth rates reached 10.0 g DW m?2 day?1 and 4.3 g DW m?2 day?1, respectively, for the SH and SW cultures, while the starch content reached 39% (w/w) and 34% (w/w). The nitrogen and phosphorus removal rate reached 80% (SH) and 90% (SW) during cultivation, and heavy metal ions assimilation was observed. About 95% (w/w) of glucose was released from duckweed biomass hydrolysates, and then fermented by Angel yeast with ethanol yield of 0.19 g g?1 (SH) and 0.17 g g?1 (SW). The amylose/amylopectin ratios of the cultures changed as starch content increased, from 0.252 to 0.155 (SH) and from 0.252 to 0.174 (SW). Lemna aequinoctialis strain 6000 could be considered as valuable feedstock for bioethanol production and water resources purification. PMID:25517893

  16. Feasibility of Producing Selenium-Enriched Water Lettuce (Pistia stratiotes L.)

    OpenAIRE

    Anut Chantiratikul; Panida Atiwetin; Piyanete Chantiratikul

    2008-01-01

    The feasibility of producing selenium-enriched water lettuce (Pistia stratiotes L.) was studied by cultivating water lettuce in Hoagland's solution containing 0, 20, 40, 60 and 80 mg Se from sodium selenite/L. There were 4 replicates in each Se concentration. Each replicate consisted of 30 plants of water lettuce. Three plants of water lettuce in each replicate were sampled on day 0, 1, 2, 3 and 4 of the experiment. The samples were washed with deionized water, separated for leaves and...

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

    OpenAIRE

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

    2015-01-01

    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/...

  18. Feasibility of Producing Selenium-Enriched Water Lettuce (Pistia stratiotes L.

    Directory of Open Access Journals (Sweden)

    Anut Chantiratikul

    2008-01-01

    Full Text Available The feasibility of producing selenium-enriched water lettuce (Pistia stratiotes L. was studied by cultivating water lettuce in Hoagland's solution containing 0, 20, 40, 60 and 80 mg Se from sodium selenite/L. There were 4 replicates in each Se concentration. Each replicate consisted of 30 plants of water lettuce. Three plants of water lettuce in each replicate were sampled on day 0, 1, 2, 3 and 4 of the experiment. The samples were washed with deionized water, separated for leaves and roots and finally dried at 65 °C. Prior to Se determination, leaf or root samples were pooled by replicate. The finding revealed that Se concentrations in leaves and roots of water lettuce increased significantly (p<0.05 with increasing Se concentration in Hoagland's solution and day of cultivation. However, Se concentration in leaves was lower than that of roots. Water lettuce cultivated in the solution containing 60 to 80 mg Se L-1 exhibited the yellow leaves and died in day 2 and 3. Therefore, the appropriate Se concentration and duration for producing Se-enriched water lettuce were 20 to 40 mg Se L-1 and 2 to 3 days of cultivation. The leaves of water lettuce cultivated in those conditions contained 11.14-13.50 and 21.06-29.55 mg Se kg-1, respectively.

  19. Plant growth-promoting bacterium Acinetobacter calcoaceticus P23 increases the chlorophyll content of the monocot Lemna minor (duckweed) and the dicot Lactuca sativa (lettuce).

    Science.gov (United States)

    Suzuki, Wakako; Sugawara, Masayuki; Miwa, Kyoko; Morikawa, Masaaki

    2014-07-01

    Acinetobacter calcoaceticus P23 is a plant growth-promoting bacterium that was isolated from the surface of duckweed (Lemna aoukikusa). The bacterium was observed to colonize on the plant surfaces and increase the chlorophyll content of not only the monocotyledon Lemna minor but also the dicotyledon Lactuca sativa in a hydroponic culture. This effect on the Lactuca sativa was significant in nutrient-poor (×1/100 dilution of H2 medium) and not nutrient-rich (×1 or ×1/10 dilutions of H2 medium) conditions. Strain P23 has the potential to play a part in the future development of fertilizers and energy-saving hydroponic agricultural technologies. PMID:24468072

  20. Ethanol production from candidate energy crops: water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.).

    Science.gov (United States)

    Mishima, D; Kuniki, M; Sei, K; Soda, S; Ike, M; Fujita, M

    2008-05-01

    Fermentation modes and microorganisms related to two typical free-floating aquatic plants, water hyacinth and water lettuce, were investigated for their use in ethanol production. Except for arabinose, sugar contents in water lettuce resembled those in water hyacinth leaves. Water lettuce had slightly higher starch contents and lower contents of cellulose and hemicellulose. A traditional strain, Saccharomyces cerevisiae NBRC 2346, produced 14.4 and 14.9 g l(-1) ethanol, respectively, from water hyacinth and water lettuce. Moreover, a recombinant strain, Escherichia coli KO11, produced 16.9 and 16.2 g l(-1) ethanol in the simultaneous saccharification and fermentation mode (SSF), which was more effective than the separated hydrolysis and fermentation mode (SHF). The ethanol yield per unit biomass was comparable to those reported for other agricultural biomasses: 0.14-0.17 g g-dry(-1) for water hyacinth and 0.15-0.16 g g-dry(-1) for water lettuce. PMID:17574848

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

    OpenAIRE

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

    2015-01-01

    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/k...

  2. Persistence, Transmission, and Virulence Characteristics of Aeromonas Strains in a Duckweed Aquaculture-Based Hospital Sewage Water Recycling Plant in Bangladesh?

    OpenAIRE

    Rahman, Mokhlasur; Huys, Geert; Rahman, Motiur; Albert, M. John; Kühn, Inger; Möllby, Roland

    2006-01-01

    The persistence and transmission of Aeromonas in a duckweed aquaculture-based hospital sewage water treatment plant in Bangladesh was studied. A total of 670 samples from different sites of the hospital sewage water treatment plant, from feces of hospitalized children suffering from diarrhea, from environmental control ponds, and from feces of healthy humans were collected over a period of three years. In total, 1,315 presumptive Aeromonas isolates were biochemically typed by the PhenePlate r...

  3. A Comparative Study of the Purification of Aquaculture Wastewater Using Water Hyacinth, Water Lettuce And Parrot's Feather

    OpenAIRE

    A. M. Snow; Abdel E. Ghaly

    2008-01-01

    Water hyacinth, water lettuce and parrots feather plants were examined for their ability to remove nutrients from aquaculture wastewater at two retention times. During the experiment, the aquatic plants grew rapidly and appeared healthy with green color. At hydraulic retention times (HRTs) of 6 and 12 days, the average water hyacinth, water lettuce and parrots feather yields were 83, 51 and 51 g (dm) m-2 and 49, 29 and 22 g (dm) m-2, respectively. The aquatic plants were able to signifi...

  4. Potential cross-contamination of E. coli between lettuce and wash water simulating an industrial fresh-cut lettuce wash process

    OpenAIRE

    Holvoet, Kevin; Sampers, Imca; Van Haute, Sam; Jacxsens, Liesbeth; UYTTENDAELE, MIEKE

    2012-01-01

    The aim was to provide information about E. coli contamination of washing water to prevent water becoming a vehicle for transfer of microbial contamination to lettuce and to get insight on the factors affecting proper water management. A lettuce wash process was simulated to determine (1) the ability to use “clean” water and the tolerable E. coli levels for “clean” water and its’ potential to respect it upon re-use of water in the first washing bath, (2) the need and effect of using potable w...

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

    Directory of Open Access Journals (Sweden)

    Guilherme Lages Barbosa

    2015-06-01

    Full Text Available 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.

  6. 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

    2015-06-01

    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. PMID:26086708

  7. Lettuce growth and water consumption in NFT hydroponic system using brackish water

    OpenAIRE

    Hammady R. Soares; Ênio F. de F. e Silva; Gerônimo F. da Silva; Pedrosa, Elvira M. R.; Mario M. Rolim; Alexandre N Santos

    2015-01-01

    The qualitative aspects of water, such as the preparation or replenishment of the nutrient solution, are critical to the success of hydroponic crops. Therefore, the aim of this study was to evaluate the behavior of “Americana” lettuce (cv. Tainá) under increasing levels of saline stress (0.2 - control, 1.2, 2.2, 3.2, 4.2 and 5.2 dS m-1), replenishing the evapotranspiration with brackish water in Experiment I and supply water (0.2 dS m-1) in Experiment II, both used in the preparation of the n...

  8. WARM WATER TREATMENT IN COMBINATION WITH MODIFIED ATMOSPHERE PACKAGING REDUCED UNDESIRABLE EFFECTS OF IRRADIATION ON THE QUALITY OF FRESH-CUT ICEBERG LETTUCE

    Science.gov (United States)

    Fresh-cut iceberg lettuce, immersed into 5 C or 47 C water for 2 min and packaged in breathable film bags, was irradiated at 0, 0.5, 1 and 2 kGy. The lettuce was then stored at 3 C for 21 days. Dipping lettuce to 47 °C water for 2 min prior to irradiation reduced antioxidant and phenolic accumulati...

  9. Assessment of Heavy Metals in Lettuce Grown in Soils Irrigated with Different Water Sources in the Accra Metropolis

    OpenAIRE

    Mark O. Akrong; Samuel J. Cobbina; Joseph A. Ampofo

    2012-01-01

    This study was carried out to assess the levels of different heavy metals like Iron, Manganese, Copper, Zinc, Cadmium and Lead in three different irrigation water sources, irrigated soils and irrigated lettuce. The result indicates positive and significant correlation of heavy metals concentrations between the irrigation water, irrigated soils and irrigated lettuce. The range of various heavy metals in drained water irrigated lettuce was 162.00-190.00, 60.25-78.25, 6.03-8.80 and 23.88-52.00 m...

  10. Growth characteristics of aquatic macrophytes cultured in nutrient-enriched water. I. Water hyacinth, water lettuce, and pennywort

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, K.R.; DeBusk, W.F.

    Seasonal growth characteristics and biomass yield potential of 3 floating aquatic macrophytes cultured in nutrient nonlimiting conditions were evaluated in central Florida's climatic conditions. Growth cycle (growth curve) of the plants was found to be complete when maximum plant density was reached and no additional increase in growth was recorded. Biomass yield per unit area and time was found to be maximum in the linear phase of the growth curve; plant density in this phase was defined as operational plant density, a density range in which a biomass production system is operated to obtain the highest possible yields. Biomass yields were found to be 106, 72, and 41 t (dry wt) ha/sup -1/ yr/sup -1/, respectively, for water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), and pennywort (Hydrocotyle umbellata). Operational plant density was found to be in the range of 500-2,000 g dry wt m/sup -2/ for water hyacinth, 200-700 g dry wt m/sup -2/ for water lettuce, and 250-650 g dry wt m/sup -2/ for pennywort. Seasonality was observed in growth rates but not in operational plant density. Specific growth rate (% increase per day) was found to maximum at low plant densities and decreased as the plant density increased. Results show that water hyacinth and water lettuce can be successfully grown for a period of about 10 mo, while pennywort, a cool season plant, can be integrated into water hyacinth/water lettuce biomass production system to obtain high yields in the winter.

  11. Growth characteristics of aquatic macrophytes cultured in nutrient-enriched water. I. Water hyacinth, water lettuce, and pennywort

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, K.R.; DeBusk, W.F.

    Seasonal growth characteristics and biomass yield potential of 3 floating aquatic macrophytes cultured in nutrient nonlimiting conditions were evaluated in central Florida's climatic conditions. Growth cycle (growth curve) of the plants was found to be complete when maximum plant density was reached and no additional increase in growth was recorded. Biomass yield per unit area and time was found to be maximum in the linear phase of the growth curve; plant density in this phase was defined as ''operational plant density,'' a density range in which a biomass production system is operated to obtain the highest possible yields. Biomass yields were found to be 106, 72, and 41 t(dry wt) ha/sup -1/yr/sup -1/, respectively, for water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), and pennywort (Hydrocotyle umbellata). Operational plant density was found to be in the range of 500-2000 g dry wt m/sup -2/ for water hyacinth, 200-700 g dry wt m/sup -2/ for water lettuce, and 250-650 g dry wt/sup -2/ for pennywort. Seasonality was observed in growth rates but not in operational plant density. Specific growth rate (% increase per day) was found to maximum at low plant densities and decreased as the plant density increased. Results show that water hyacinth and water lettuce can be successfully grown for a period of about 10 mo, while pennywort, a cool season plant, can be integrated into water hyacinth/water lettuce biomass production system to obtain high yields in the winter.

  12. Modeling duckweed growth in wastewater treatment systems

    Science.gov (United States)

    Landesman, L.; Parker, N.C.; Fedler, C.B.; Konikoff, M.

    2005-01-01

    Species of the genera Lemnaceae, or duckweeds, are floating aquatic plants that show great promise for both wastewater treatment and livestock feed production. Research conducted in the Southern High Plains of Texas has shown that Lemna obscura grew well in cattle feedlot runoff water and produced leaf tissue with a high protein content. A model or mathematical expression derived from duckweed growth data was used to fit data from experiments conducted in a greenhouse in Lubbock, Texas. The relationship between duckweed growth and the total nitrogen concentration in the mediium follows the Mitscherlich Function and is similar to that of other plants. Empirically derived model equations have successfully predicted the growth response of Lemna obscura.

  13. Potential of domestic sewage effluent treated as a source of water and nutrients in hydroponic lettuce

    OpenAIRE

    Renata da Silva Cuba; João Rios do Carmo; Claudinei Fonseca Souza; Reinaldo Gaspar Bastos

    2015-01-01

    The search for alternative sources of water for agriculture makes the use of treated sewage sludge an important strategy for achieving sustainability. This study evaluated the feasibility of reusing treated sewage effluent as alternative source of water and nutrients for the hydroponic cultivation of lettuce (Lactuca sativa L). The experiment was conducted in the greenhouse of the Center for Agricultural Sciences - UFSCar, in Araras, SP. The cultivation took place from February to March 2014....

  14. Organic duckweed management with pelargonic acid

    Science.gov (United States)

    Duckweed (Lemna spp.) are small, free floating aquatic plants that flourish on stagnant or slow moving water surfaces throughout the continental U.S. They are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive tendencies make them formida...

  15. Phytoremediation of parboiled rice mill wastewater using water lettuce (pistia stratiotes).

    Science.gov (United States)

    Mukherjee, Bidisha; Majumdar, Madhurina; Gangopadhyay, Amitava; Chakraborty, Sankar; Chaterjee, Debashish

    2015-01-01

    Phytoremediation is an emerging technology applied for treatment of wastewater. It is a suitable option notably in developing countries as it is simple, sustainable and cost effective. In the present lab-based batch study the free floating aquatic plant water lettuce (Pistia stratiotes) is used for treatment of parboiled rice mill wastewater having low pH, high chemical oxygen demand (COD), nitrogen, and phosphate. In raw rice mill wastewater (undiluted) growth of water lettuce is found to be inhibited. Later on, two different dilution approaches (raw and facultative pond effluent 1:1; raw and tap water 1:1) are applied in order to effectively use this technology. In all cases a control (without plant) is maintained to compare the performance with the Aquatic Plant based Treatment (APT) system. In the APT system results reveal that removal of soluble COD (SCOD), ammoniacal nitrogen (NH4-N), nitrate nitrogen (NO3-N), and soluble phosphorus (sol. P) are upto 65%, 98%, 70%, and 65% respectively. The study highlights the efficacy of water lettuce in removing organics and nutrients from parboiled rice mill wastewater. PMID:25192197

  16. Toxicity and genotoxicity of water and sediment from streams on dotted duckweed (Landoltia punctata).

    Science.gov (United States)

    Factori, R; Leles, S M; Novakowski, G C; Rocha, C L S C; Thomaz, S M

    2014-11-01

    Most rivers are used as a source to supply entire cities; the quality of water is directly related to the quality of tributaries. Unfortunately men have neglected the importance of streams, which receive domestic and industrial effluents and transport nutrients and pesticides from rural areas. Given the complexity of the mixtures discharged into these water bodies, this study aimed to evaluate the quality of water and sediment of ten tributaries of Pirapó River, in Maringá, Paraná State, Brazil. To this end, the free-floating macrophyte Landoltia punctata (G. Meyer) Les & D.J.Crawford was used as test organism in microcosm, and the toxicity of water and sediment samples was evaluated by the relative growth rate, dry/fresh biomass ratio, and genotoxic effects (comet assay). Samples of water and sediment of each stream were arranged in microcosms with L. punctata. Seven days later, plants were collected for analysis. Nutrient levels were higher than the reference location, indicating eutrophication, but the results indicated a toxic effect for only three streams, and a genotoxic effect for all streams. PMID:25627585

  17. EFFECTIVENESS OF ELECTROLYZED OXIDIZING WATER FOR INACTIVATING Listeria monocytogenes IN LETTUCE

    Directory of Open Access Journals (Sweden)

    Casadiego Laíd Paola

    2005-06-01

    Full Text Available The effectiveness of electrolyzed oxidizing (EO water for the inactivation of L. monocytogenes in suspension and when inoculated on lettuce leaves was evaluated. An electrolytic cell for the production of EO water was built and a solution of 5% NaCl was used. The EO water produced had a residual chlorine concentration of 29 parts per million (ppm and pH 2.83. Ten strains of L. monocytogenes isolated from processed chicken (109 CFU/ml were inoculated into 9 ml of EO water or 9 ml of deionized water (control and incubated at 15°C for 5, 10, 15 and 20 min. The surviving population of each strain was determined on Columbia agar. An exposure time of 5 min reduced the populations by approximately 6.6 log CFU/ml. The most resistant strains to sodium hypochlorite (NaOCl were selected and used in a strain mixture (9.56 log CFU/ml, 109UFC/ml approximately for the inoculation of 35 lettuce samples, by the dip inoculation method using distilled water as control. The population mean of L. monocytogenes after treatment with EO water and distilled water was reduced by 3.92 and 2.46 log CFU/ml respectively (p=0.00001. EO water and 6% acetic acid (vinegar were combined to improve the EO water effect on L. monocytogenes inoculated in lettuce; the effectiveness of this combination was examined. The results showed that there was a synergistic effect of both antimicrobial agents (population reduction by 5.49 log CFU/ml approximately on the viability of L. monocytogenes cells.

  18. THE ROLE OF DUCKWEED (LEMNA MINOR L.) IN SECONDARY CLARIFIER TANKS

    OpenAIRE

    Engin Gürtekin; Nusret ?ekerda?

    2008-01-01

    In this study, the effects of duckweed (Lemna minor L.) presence on the effluent water quality and settling characteristics in the secondary clarifier tank of a conventional biological treatment plant were investigated. For this purpose, the performances of the secondary clarifier with and without duckweed were compared. In the secondary clarifier tank with duckweed, COD, BOD5, ammonium and phosphate removal efficiencies were higher by 15, 25, 35 and 45%, respectively. SS concentration of eff...

  19. A Comparative Study of the Purification of Aquaculture Wastewater Using Water Hyacinth, Water Lettuce And Parrot's Feather

    Directory of Open Access Journals (Sweden)

    A. M. Snow

    2008-01-01

    Full Text Available Water hyacinth, water lettuce and parrotÂ’s feather plants were examined for their ability to remove nutrients from aquaculture wastewater at two retention times. During the experiment, the aquatic plants grew rapidly and appeared healthy with green color. At hydraulic retention times (HRTs of 6 and 12 days, the average water hyacinth, water lettuce and parrotÂ’s feather yields were 83, 51 and 51 g (dm m-2 and 49, 29 and 22 g (dm m-2, respectively. The aquatic plants were able to significantly reduce the pollution load of the aquaculture wastewater. The TS, COD, NH4+-N, NO2--N, NO3--N and PO43--P reductions ranged from 21.4 to 48.0%, from 71.1 to 89.5%, from 55.9 to 76.0%, from 49.6 to 90.6%, from 34.5 to 54.4% and from 64.5 to 76.8%, respectively. Generally, the reductions increased with longer retention times and were highest in compartments containing water hyacinth followed by compartments containing water lettuce and parrotÂ’s feather. In terms of COD, NO3--N and PO43--P, the effluent leaving the hydroponics system was suitable for reuse in aquaculture. However, the effluent had slightly high levels of TS, NH3-N, NO2--N and pH after treatment.

  20. THE ROLE OF DUCKWEED (LEMNA MINOR L. IN SECONDARY CLARIFIER TANKS

    Directory of Open Access Journals (Sweden)

    Engin Gürtekin

    2008-01-01

    Full Text Available In this study, the effects of duckweed (Lemna minor L. presence on the effluent water quality and settling characteristics in the secondary clarifier tank of a conventional biological treatment plant were investigated. For this purpose, the performances of the secondary clarifier with and without duckweed were compared. In the secondary clarifier tank with duckweed, COD, BOD5, ammonium and phosphate removal efficiencies were higher by 15, 25, 35 and 45%, respectively. SS concentration of effluent and values of sludge volume index (SVI were the same. The results showed that duckweed contributes to treatment efficiency of conventional biological treatment plant, which reduces the need of tertiary nutrients removal.

  1. Application of duckweed for human urine treatment in Bioregenerative Life Support System

    Science.gov (United States)

    Manukovsky, Nickolay; Kovalev, Vladimir

    The object of the study was the common duckweed Lemna minor L. Thanks to the ability to assimilate mineral and organic substances, duckweed is used to purify water in sewage lagoons. In addition, duckweed biomass is known to be a potential high-protein feed resource for domestic animals and fish. The aim of the study was to estimate an application of duckweed in a two-stage treatment of human urine in Bioregenerative Life Support System (BLSS). At the first stage, the urine’s organic matter is oxidized by hydrogen peroxide. Diluted solution of oxidized urine is used for cultivation of duckweed. The appointment of duckweed is the assimilation of mineralized substances of urine. Part of the duckweed biomass yield directly or after composting could be embedded in the soil-like substrate as organic fertilizer to compensate the carry-over in consequence of plant growing. The rest duckweed biomass could be used as a feed for animals in BLSS. Then, the residual culture liquid is concentrated and used as a source of dietary salt. It takes 10-15 m2 of duckweed culture per crewmember to treat oxidized urine. The BLSS configuration including two-component subsystem of urine treatment is presented.

  2. A study on cadmium phytoremediation potential of water lettuce, Pistia stratiotes L.

    Science.gov (United States)

    Das, Suchismita; Goswami, Sunayana; Talukdar, Anupam Das

    2014-02-01

    Aquatic macrophytes have tremendous potential for remediation of the heavy metal cadmium. The objective of this study was to investigate Cd phytoremediation ability of water lettuce, Pistia stratiotes L. The study was conducted with 5, 10, 15 and 20 mg L(-1) CdCl2 in hydroponic system for 21 days and the Cd concentrations in the root and shoot tissues were estimated by atomic absorption spectroscopy. The values obtained were used to evaluate the bioconcentration factor (BCF), translocation factor (TF) and translocation efficiency of this plant. The plant showed high Cd tolerance of up to 20 mg L(-1) but there was a general trend of decline in the root and shoot biomass. The maximum BCF values for root and shoot tissues were 2,294 and 870 respectively, obtained for 5 mg L(-1) Cd, which indicated that the plant was a Cd hyperaccumulator. The TF maxima was found to be 0.6 and as much as 60 % root to shoot translocation efficiency was observed for 15 mg L(-1) Cd which points towards the suitability of water lettuce for removing Cd from surface waters. PMID:24220931

  3. Resurgence of duckweed research and applications: report from the 3rd International Duckweed Conference.

    Science.gov (United States)

    Appenroth, Klaus-J; Sree, K Sowjanya; Fakhoorian, Tamra; Lam, Eric

    2015-12-01

    Duckweed, flowering plants in the Lemnaceae family, comprises the smallest angiosperms in the plant kingdom. They have some of the fastest biomass accumulation rates reported to date for plants and have the demonstrated ability to thrive on wastewater rich in dissolved organic compounds and thus could help to remediated polluted water resources and prevents eutrophication. With a high quality genome sequence now available and increased commercial interest worldwide to develop duckweed biomass for renewables such as protein and fuel, the 3rd International Duckweed Conference convened at Kyoto, Japan, in July of 2015, to update the community of duckweed researchers and developers on the progress in the field. In addition to sharing results and ideas, the conference also provided ample opportunities for new-comers as well as established workers in the field to network and create new aliances. We hope this meeting summary will also help to disseminate the key advances and observations that have been presented in this conference to the broader plant biology community in order to encourage increased cross-fertilization of ideas and technologies. PMID:26506824

  4. Effect of irrigation water on the incidence of Salmonella spp. on lettuces produced by urban agriculture and sold on the markets in Dakar, Senegal

    OpenAIRE

    Ndiaye, Mamadou Lamine; Dieng, Y.; Niang, S.; Pfeifer, H.R.; Tonolla, M.; Peduzzi, Raffael

    2011-01-01

    The aim of our survey was to assess the effect of irrigation water of the microbiological quality on the production chain of lettuce in the Dakar area. Microbiological analysis showed that 35% of irrigation water was contaminated by Salmonella spp. between the two water-types used for irrigation (groundwater and wastewater), no significant difference (p>0.05) in their degree of contamination was found. The incidence of different types of irrigation water on the contamination rate of lettuces ...

  5. Duck-Weed as an ecotoxicological biotest

    International Nuclear Information System (INIS)

    Since 1989 duck-weed (Spirodela polyrrhiza) has been used as an ecotoxicological biotest at the Radioecological Section of Institute of Botany. It was used to estimate precipitation toxicity of Mazheikiai and Akmene regions, waste waters of industrial galvanic departments, water reservoirs of the Ignalina and Leningrad NPP, also the Dniepr cascade. The data obtained showed Spirodela polyrrhiza to be a rather sensitive and specific biotest for the estimation of contamination with heavy metals. Spirodela polyrrhiza is advisable to estimate pollution of the air, waste-waters and solutions of heavy metals. (author). 12 refs., 3 figs., 4 tabs

  6. Growing duckweed for biofuel production: a review.

    Science.gov (United States)

    Cui, W; Cheng, J J

    2015-01-01

    Duckweed can be utilised to produce ethanol, butanol and biogas, which are promising alternative energy sources to minimise dependence on limited crude oil and natural gas. The advantages of this aquatic plant include high rate of nutrient (nitrogen and phosphorus) uptake, high biomass yield and great potential as an alternative feedstock for the production of fuel ethanol, butanol and biogas. The objective of this article is to review the published research on growing duckweed for the production of the biofuels, especially starch enrichment in duckweed plants. There are mainly two processes affecting the accumulation of starch in duckweed biomass: photosynthesis for starch generation and metabolism-related starch consumption. The cost of stimulating photosynthesis is relatively high based on current technologies. Considerable research efforts have been made to inhibit starch degradation. Future research need in this area includes duckweed selection, optimisation of duckweed biomass production, enhancement of starch accumulation in duckweeds and use of duckweeds for production of various biofuels. PMID:24985498

  7. Phytoremediation Potential of Duckweed (Lemna minor L.) On Steel Wastewater.

    Science.gov (United States)

    Saha, Priyanka; Banerjee, Angela; Sarkar, Supriya

    2015-01-01

    An eco-friendly and cost effective technique- phytoremediation was used to remediate contaminants from waste water. This study demonstrated that phytoremediation ability of duckweed (Lemna minor L.) to remove chloride, sulphate from Biological Oxygen Treatment (BOT) waste water of coke oven plant. The BOT water quality was assessed by analyzing physico-biochemical characters--pH, Biological oxygen demand (BOD), Chemical oxygen demand (COD), total dissolved solids (TDS) and elemental concentration. It was observed that an increase in pH value indicated an improvement of water quality. The experimental results showed that, duckweed effectively removed 30% chloride, 16% sulphate and 14% TDS from BOT waste water, which suggested its ability in phytoremediation for removal of chloride and sulphate from BOT waste water. A maximum increase of 30% relative growth rate of duckweed was achieved after 21 days of experiment. Thus, it was concluded that duckweed, an aquatic plant, can be considered for treatment of the effluent discharged from the coke oven plant. PMID:25192438

  8. Assessing water hyacinth (Eichhornia crassopes) and lettuce (Pistia stratiotes) effectiveness in aquaculture wastewater treatment.

    Science.gov (United States)

    Akinbile, C O; Yusoff, Mohd S

    2012-03-01

    Water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) were analyzed to determine their effectiveness in aquaculture wastewater treatment in Malaysia. Wastewater from fish farm in Semanggol Perak, Malaysia was sampled and the parameters determined included, the pH, turbidity, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), nitrite phosphate (PO4(3-)), nitrate (NO(3-)), nitrite (NO(-2)), ammonia (NH3), and total kjedahl nitrogen (TKN). Also, hydroponics system was set up and was added with fresh plants weights of 150 +/- 20 grams Eichhornia crassipes and 50 +/- 10 grams Pistia stratiotes during the 30 days experiment. The phytoremediation treatment with Eichhornia crassipes had pH ranging from 5.52 to 5.59 and from 4.45 to 5.5 while Pistia stratiotes had its pH value from 5.76 to 6.49 and from 6.24 to 7.07. Considerable percentage reduction was observed in all the parameters treated with the phytoremediators. Percentage reduction of turbidity for Eichhornia crassipes were 85.26% and 87.05% while Pistia stratiotes were 92.70% and 93.69% respectively. Similar reductions were observed in COD, TKN, NO(3-), NH3, and PO4(3-). The capability of these plants in removing nutrients was established from the study. Removal of aquatic macrophytes from water bodies is recommended for efficient water purification. PMID:22567705

  9. Potential of domestic sewage effluent treated as a source of water and nutrients in hydroponic lettuce

    Directory of Open Access Journals (Sweden)

    Renata da Silva Cuba

    2015-07-01

    Full Text Available The search for alternative sources of water for agriculture makes the use of treated sewage sludge an important strategy for achieving sustainability. This study evaluated the feasibility of reusing treated sewage effluent as alternative source of water and nutrients for the hydroponic cultivation of lettuce (Lactuca sativa L. The experiment was conducted in the greenhouse of the Center for Agricultural Sciences - UFSCar, in Araras, SP. The cultivation took place from February to March 2014. The hydroponic system used was the Nutrient Film Technique, and included three treatments: 1 water supply and mineral fertilizers (TA; 2 use of effluent treated and complemented with mineral fertilizers based on results of previous chemical analysis (TRA; and 3 use of treated effluent (TR. The applied experimental design was four randomly distributed blocks. We evaluated the fresh weight, nutritional status, the microbiological quality of the culture, and the amount of mineral fertilizers used in the treatments. The fresh weights were subjected to analysis of variance and means were compared by the Tukey test at 5% probability. Only the TR treatment showed a significant difference in the evaluated variables, as symptoms of nutritional deficiencies in plants and significant reduction in fresh weights (p <0.01 were found. There was no detectable presence of Escherichia coli in any treatment, and it was possible to use less of some fertilizers in the TRA treatment compared to TA.

  10. Enteric Pathogen Survival Varies Substantially in Irrigation Water from Belgian Lettuce Producers

    Directory of Open Access Journals (Sweden)

    Inge Van Der Linden

    2014-09-01

    Full Text Available It is accepted that irrigation water is a potential carrier of enteric pathogens, such as Salmonella and E. coli O157:H7 and, therefore, a source for contamination of fresh produce. We tested this by comparing irrigation water samples taken from five different greenhouses in Belgium. The water samples were inoculated with four zoonotic strains, two Salmonella and two E. coli O157:H7 strains, and pathogen survival and growth in the water were monitored up till 14 days. The influence of water temperature and chemical water quality was evaluated, and the survival tests were also performed in water samples from which the resident aquatic microbiota had previously been eliminated by filter sterilization. The pathogen’s survival differed greatly in the different irrigation waters. Three water samples contained nutrients to support important growth of the pathogens, and another enabled weaker growth. However, for all, growth was only observed in the samples that did not contain the resident aquatic microbiota. In the original waters with their specific water biota, pathogen levels declined. The same survival tendencies existed in water of 4 °C and 20 °C, although always more expressed at 20 °C. Low water temperatures resulted in longer pathogen survival. Remarkably, the survival capacity of two E. coli 0157:H7 strains differed, while Salmonella Thompson and Salmonella Typhimurium behaved similarly. The pathogens were also transferred to detached lettuce leaves, while suspended in two of the water samples or in a buffer. The effect of the water sample on the pathogen’s fitness was also reproduced on the leaves when stored at 100% relative humidity. Inoculation of the suspension in buffer or in one of the water samples enabled epiphytic growth and survival, while the pathogen level in the other water sample decreased once loaded on the leaves. Our results show that irrigation waters from different origin may have a different capacity to transmit enteric pathogens and an important impact on the fitness of the pathogens to sustain and even grow on the leaf surface.

  11. Pelargonic acid - a potential organic aquatic herbicide for duckweed management

    Science.gov (United States)

    Duckweed (Lemna spp.) are small, free floating aquatic plants that flourish on stagnant, or slow moving, water surfaces throughout the continental U.S. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive habit make...

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

    OpenAIRE

    Humberto Brevilato Novaes; Delmo Santiago Vaitsman; Paulo Bechara Dutra; Daniel Vidal Pérez

    2009-01-01

    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 micr...

  13. Dried duckweed and commercial feed promote adequate growth performance of tilapia fingerlings

    Directory of Open Access Journals (Sweden)

    Juan Esquivel

    2008-09-01

    Full Text Available The present study evaluated Nile tilapia when fed on dried duckweed in combination with commercial feed, aiming at reducing production costs. Three diets, which consisted of commercial feed (40% crude protein, dried duckweed or a combination of commercial feed and dried duckweed were fed to triplicate groups of 20 tilapia (Oreochromis niloticus fingerlings. Fish weighing 3.2 ± 0.94g were stocked in nine 1-m3 net cages and fed twice a day for 50 days. The final average weights of fingerlings fed commercial feed (21.67g and50% feed + 50% dried duckweed (19.53g were not different (p<0.05. Likewise, the specific growth rate did not differ between fish receiving these dietary treatments. Weight gain decreased as water temperature decreased along the experimental period, increasing feed conversion mainly for fingerlings fed on dried duckweed only. Also, when fed alone dried duckweed promoted the lowest weight gain and specific growth rate. It was confirmed that dried duckweed can replace 50% (1:1 dry weight tilapia fingerling 40% crude protein feed for a period of at least 50 days, without reducing growth.

  14. Estudio de comparación del tratamiento de aguas residuales domésticas utilizando lentejas y buchón de agua en humedales artificiales / Comparative study of domestic wastewater treatments using common duckweed (Lemna minor) and water hyacint (Eichhornia crassipes) in artificial wetlands

    Scientific Electronic Library Online (English)

    Juan Pablo, Rodríguez-Miranda; Esteban, Gómez; Laura, Garavito; Francy, López.

    2010-03-01

    Full Text Available El estudio de comparación del tratamiento de aguas residuales domésticas utilizando sistemas naturales como los humedales artificiales presenta resultados de remoción de materia orgánica (DBO5) de entre 70 y 86% al utilizar el buchón de agua, y de 58% cuando se utiliza lenteja de agua. El sistema de [...] humedales artificiales se comporta hidráulicamente como un modelo de flujo pistón, sin distinción del tipo de planta acuática que se use. Durante la experimentación se observó que cuando se utilizó la lenteja de agua en el humedal artificial, ésta le aportó al agua elementos característicos de la planta que aumentan el pH (> 11) en el agua efluente; mientras que con el buchón de agua, los valores de pH del agua están en el rango de 6 a 8.0, favoreciendo la estabilización de la materia orgánica dentro del sistema biológico. Abstract in english This comparative study of domestic wastewater treatment using natural systems like artificial wetlands shows organic matter (BOD) removal rates between 70% and 86% using water hyacinth and of 58% using common duckweed. The artificial wetland system behaves hydraulically as a piston-flow model regard [...] less of the aquatic plant used. During the experiment, it was observed that common duckweed contributes characteristic elements to water that increase the effluent's pH (> 11), whereas water hyacinth elevates the pH value in the range of 6-8, thus favoring the stabilization of the organic matter within the biological system.

  15. Arsenic reduction from aqueous environment by water lettuce (Pistia stratiotes L.).

    Science.gov (United States)

    Basu, Arindam; Kumar, Sunil; Mukherjee, Somnath

    2003-04-01

    Arsenate uptake by aquatic plant water lettuce (Pistia stratiotes L.) was studied in the laboratory condition to investigate a low cost natural aquatic treatment system for pollutant removal. The plants were harvested from a local pollution free pond in young condition and hydroponically cultured in the laboratory. Bioaccumulation was noticed to be both concentration and duration dependent. The results show that the plant could effectively abosrb arsenic between a range of 0.25 to 5.0 mg/l to the extent of 82.0 to 22.8% for a biomass of 20g/l at pH 7.0 after 144 hours. The results were also plotted in Langmuir and Freundlich isotherms and the data were well fitted. The sorption capacity was evaluated as 1.43 mg/g for Langmuir isotherm and 1.01 mg/g for Freundlich isotherm. The removal efficiency was, however, noted to be maximum (87.5%) at pH 6.5. The effect of biomass quantity has also been investigated along with some metabolic parameters. PMID:15270347

  16. Uptake, biotransformation, and elimination of {sup 99}Tc in duckweed

    Energy Technology Data Exchange (ETDEWEB)

    Hattink, Jasper; Harms, Arend V.; De Goeij, Jeroen J.M. [Interfaculty Reactor Institute, Mekelweg 15, 2629 JB Delft (Netherlands)

    2003-08-01

    Aquatic plants may play an important role in the environmental fate of the long-lived radioactive waste product {sup 99}Tc. Aquatic plants show a strong accumulation and retention of Tc, even after they have died. This study focuses on possible bio-organic Tc compounds formed in the water dwelling plant duckweed to possibly explain the accumulation and retention. Moreover, a change in chemical speciation often implies a different fate and behaviour in the biosphere. A mild separation technique was used to distinguish between reduced Tc species and TcO{sub 4}{sup -}. Accumulation experiments suggested that reduction of Tc{sup VII}O{sub 4}{sup -} and subsequent complexation are responsible for the accumulation of Tc in duckweed. A steady state concentration of TcO{sub 4}{sup -} in duckweed was reached within 24 h, but the total concentration of Tc increased continuously. Only a small part ({<=}5%) of Tc was present as TcO{sub 4}{sup -}. Elimination experiments showed that TcO{sub 4}{sup -} is the only mobile species. Other Tc species are responsible for the retention of Tc in duckweed. It is known that these species are not bio-available and only slowly re-oxidise to pertechnetate, resulting in a longer residence time in ecosystems.

  17. Uptake, biotransformation, and elimination of 99Tc in duckweed

    International Nuclear Information System (INIS)

    Aquatic plants may play an important role in the environmental fate of the long-lived radioactive waste product 99Tc. Aquatic plants show a strong accumulation and retention of Tc, even after they have died. This study focuses on possible bio-organic Tc compounds formed in the water dwelling plant duckweed to possibly explain the accumulation and retention. Moreover, a change in chemical speciation often implies a different fate and behaviour in the biosphere. A mild separation technique was used to distinguish between reduced Tc species and TcO4-. Accumulation experiments suggested that reduction of TcVIIO4- and subsequent complexation are responsible for the accumulation of Tc in duckweed. A steady state concentration of TcO4- in duckweed was reached within 24 h, but the total concentration of Tc increased continuously. Only a small part (?5%) of Tc was present as TcO4-. Elimination experiments showed that TcO4- is the only mobile species. Other Tc species are responsible for the retention of Tc in duckweed. It is known that these species are not bio-available and only slowly re-oxidise to pertechnetate, resulting in a longer residence time in ecosystems

  18. Accumulation of contaminants of emerging concern in food crops-part 1: Edible strawberries and lettuce grown in reclaimed water.

    Science.gov (United States)

    Hyland, Katherine C; Blaine, Andrea C; Dickenson, Eric R V; Higgins, Christopher P

    2015-10-01

    Contaminants of emerging concern present in domestic waste streams include a highly diverse group of potentially biologically active compounds that can be detected at trace levels in wastewater. Concerns about potential uptake into crops arise when reclaimed water is used in food crop production. The present study investigated how 9 contaminants of emerging concern in reclaimed water are taken up into edible portions of two food crops. Two flame retardant chemicals, tris(1-chloro-2-propyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) and several polar pharmaceuticals (carbamazepine, diphenhydramine, sulfamethoxazole, and trimethoprim) accumulated in a linear, concentration-dependent manner in lettuce (Lactuca sativa) irrigated with reclaimed water, suggesting passive uptake of both neutral and ionizable chemical contaminants in lettuce. Furthermore, concentration-dependent accumulation of TCEP and TCPP from reclaimed water was also observed in strawberry fruits (Fragaria ananassa). Collectively, these data suggest that highly polar or charged contaminants can be taken up by crops from water bearing contaminants of emerging concern and can be accumulated in the edible portions. Using these data, however, estimates of human exposure to these contaminants from reclaimed water food crop accumulation suggest that exposure to the contaminants of emerging concern examined in the present study is likely substantially lower than current exposure guidelines. PMID:25988333

  19. Influence of season growth, soils and irrigation water composition on the concentration of uranium in two lettuce (Lactuca sativa L.) varieties. Field experiments

    Science.gov (United States)

    Abreu, M. M.; Neves, O.; Marcelino, M.

    2012-04-01

    Former uranium mines areas are frequently the sources of environmental radionuclides problems even many years after the closure of mining operations. A concern for inhabitants from mining areas is the use of contaminated land or irrigation water for agriculture, and the potential transfer of metals from soils to vegetables, and to humans through the food chain. The main aim of this study was to compare the uranium concentration in lettuce (Lactuca sativa L. varieties Marady and Romana) grown in different seasons (autumn and summer) and exposed to high and low uranium concentrations both in irrigation water and agricultural soil. The content of uranium in irrigation water, soil (total and available fraction) and in lettuce leaf samples was analyzed in a certified laboratory. In the field experiments, two agricultural soils were divided into two plots (four replicates each); one of them was irrigated with uranium contaminated water (0.94 to 1.14 mg/L) and the other with uncontaminated water (lettuce varieties, namely yield reduction (up to 53% and 87% in autumn and summer experiments, respectively) and increase of uranium leaf concentration (up to 1.4 and 7 fold in autumn and summer, respectively). Effect on lettuce yield was mainly due to the high soil salinity (1.01 to 6.31 mS/cm) as a consequence of high irrigation water electrical conductivity (up to 1.82 mS/cm) and low lettuce soil salinity tolerance (1 to 3 mS/cm). The highest lettuce uranium concentration (dry weight) observed was 2.13 and 5.37 mg/kg for Marady and Romana variety, respectively. The highest uranium lettuce concentration in Romana variety was also the effect of its growing in summer season when it was subject to greatest frequency and amount of water irrigation. The consumption by an adult of the lettuce that concentrate more uranium, represents only 16.7% of the tolerable daily limit intake set by World Health Organisation for this element (0.6 mg/kg body weight daily), suggesting that lettuce uranium intake had a low contribution and do not represent a potential health risk for Cunha Baixa's residents.

  20. 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.

  1. Accumulation of arsenic in Lemna gibba L. (duckweed) in tailing waters of two abandoned uranium mining sites in Saxony, Germany

    Energy Technology Data Exchange (ETDEWEB)

    Mkandawire, Martin; Dudel, E. Gert

    2005-01-05

    Accumulation of arsenic in Lemna gibba L. was investigated in tailing waters of abandoned uranium mine sites, following the hypothesis that arsenic poses contamination risks in post uranium mining in Saxony, Germany. Consequently, macrophytes growing in mine tailing waters accumulate high amounts of arsenic, which might be advantageous for biomonitoring arsenic transfer to higher trophic levels, and for phytoremediation. Water and L. gibba sample collected from pond on tailing dumps of abandoned mine sites at Lengenfeld and Neuensalz-Mechelgruen were analysed for arsenic. Laboratory cultures in nutrient solutions modified with six arsenic and three PO{sub 4}{sup 3-} concentrations were conducted to gain insight into the arsenic-L. gibba interaction. Arsenic accumulation coefficients in L. gibba were 10 times as much as the background concentrations in both tailing waters and nutrient solutions. Arsenic accumulations in L. gibba increased with arsenic concentration in the milieu but they decreased with phosphorus concentration. Significant reductions in arsenic accumulation in L. gibba were observed with the addition of PO{sub 4}{sup 3-} at all six arsenic test concentrations in laboratory experiments. Plant samples from laboratory trials had on average twofold higher bioaccumulation coefficients than tailing water at similar arsenic concentrations. This would be attributed to strong interaction among chemical components, and competition among ions in natural aquatic environment. The results of the study indicate that L. gibba can be a preliminary bioindicator for arsenic transfer from substrate to plants and might be used to monitor the transfer of arsenic from lower to higher trophic levels in the abandoned mine sites. There is also the potential of using L. gibba L. for arsenic phytoremediation of mine tailing waters because of its high accumulation capacity as demonstrated in this study. Transfer of arsenic contamination transported by accumulations in L. gibba carried with flowing waters, remobilisation through decay, possible methylisation and volatilisation by L. gibba need to be considered.

  2. Accumulation of arsenic in Lemna gibba L. (duckweed) in tailing waters of two abandoned uranium mining sites in Saxony, Germany

    International Nuclear Information System (INIS)

    Accumulation of arsenic in Lemna gibba L. was investigated in tailing waters of abandoned uranium mine sites, following the hypothesis that arsenic poses contamination risks in post uranium mining in Saxony, Germany. Consequently, macrophytes growing in mine tailing waters accumulate high amounts of arsenic, which might be advantageous for biomonitoring arsenic transfer to higher trophic levels, and for phytoremediation. Water and L. gibba sample collected from pond on tailing dumps of abandoned mine sites at Lengenfeld and Neuensalz-Mechelgruen were analysed for arsenic. Laboratory cultures in nutrient solutions modified with six arsenic and three PO43- concentrations were conducted to gain insight into the arsenic-L. gibba interaction. Arsenic accumulation coefficients in L. gibba were 10 times as much as the background concentrations in both tailing waters and nutrient solutions. Arsenic accumulations in L. gibba increased with arsenic concentration in the milieu but they decreased with phosphorus concentration. Significant reductions in arsenic accumulation in L. gibba were observed with the addition of PO43- at all six arsenic test concentrations in laboratory experiments. Plant samples from laboratory trials had on average twofold higher bioaccumulation coefficients than tailing water at similar arsenic concentrations. This would be attributed to strong interaction among chemical components, and competition among ions in natural aquatic environment. The results of the study indicate that L. gibba can be a preliminary bioindicator for arsenic transfer from substrate to plants and might be used to monitor the transfer of arsenic from lower to higher trophic levels in the abandoned mine sites. There is also the potential of using L. gibba L. for arsenic phytoremediation of mine tailing waters because of its high accumulation capacity as demonstrated in this study. Transfer of arsenic contamination transported by accumulations in L. gibba carried with flowing waters, remobilisation through decay, possible methylisation and volatilisation by L. gibba need to be considered

  3. Biofortification of lettuce (Lactuca sativa L.) with iodine: The effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce grown in water culture

    OpenAIRE

    Voogt, W.; Holwerda, H.T.; Khodabaks, M.R.

    2010-01-01

    BACKGROUND: Iodine is an essential trace element for humans. Two billion individuals have insufficient iodine intake. Biofortification of vegetables with iodine offers an excellent opportunity to increase iodine intake by humans. The main aim was to study the effect of iodine form and concentration in the nutrient solution on growth, development and iodine uptake of lettuce, grown in water culture. RESULTS: In both a winter and summer trial, dose rates of 0, 13, 39, 65, and 90 or 129 µg iodi...

  4. Copper-induced growth inhibition, oxidative stress and ultrastructural alterations in freshly grown water lettuce (Pistia stratiotes L.).

    Science.gov (United States)

    Upadhyay, Rishi Kesh; Panda, Sanjib Kumar

    2009-07-01

    The effects of increasing concentrations of copper on the growth, ultra-structure and on certain biochemical parameters of water lettuce (Pistia stratiotes L.) were investigated under controlled conditions in the nutrient solutions containing increased copper sulfate concentrations ranging from 0 to 100 microM. Copper treatment for 12, 18 or 24 h resulted in inhibition of roots and leaves dry biomass. Atomic absorption spectrometry analysis of roots and leaves showed that copper accumulation increased with increase in concentration and duration of metal treatment. It is seen that copper resulted in increased production of hydrogen peroxide and superoxide radical in both roots and leave cells, showed a significant change after 24 h of treatment. Also, the significant decrease in the contents of total protein and photosynthetic pigments was observed. The antioxidant enzymes, viz., peroxidase (POX, E.C.1.11.1.7), catalase (CAT, E.C.1.11.1.6) and superoxide dismutase (SOD, E.C.1.15.1.1) showed significant variation with the increase in lipid peroxidation. Increasing trends was observed in levels of ascorbate and glutathione. The rapid inducibility of some of these enzymes are useful early and sensitive indicators of heavy metal toxicity. The results demonstrated that exposure to elevated concentration of Cu had a remarkable effect on the biochemistry and physiology, induced oxidative stress in water lettuce characterized by the initiation of lipid peroxidation that inhibited growth and disintegration of major antioxidant systems. PMID:19523602

  5. The distribution of submersed aquatic vegetation and water lettuce in the fresh and oligohaline tidal Potomac River, 2007

    Science.gov (United States)

    Campbell, Sarah Hunter; Rybicki, Nancy B.; Schenk, Edward R.

    2015-01-01

    Surveys documenting the composition of species of submersed aquatic vegetation (SAV) have been conducted in the Potomac River for decades. These surveys can help managers assess the proportion of native and exotic plants in the river or can be used to determine relationships between native and exotic plants, environmental conditions, and wildlife. SAV coverage increased from 2005 to 2007 throughout the fresh and oligohaline study area. The 2007 survey documented here determined that eleven species of SAV were present. The abundance of the exotic species Hydrilla verticillata (hydrilla) was relatively low, and species diversity was relatively high compared to previous years. The survey also revealed a new population of the invasive, floating aquatic plant Pistia stratiotes (water lettuce). In 2007, water lettuce, the latest exotic aquatic plant to be found in the fresh to oligohaline portion of the Potomac River, was most abundant in Mattawoman Creek, Charles County, Maryland. However, it was not observed in the fresh to oligohaline portion of the Potomac River in the summer of 2008. An understanding of the distribution of SAV species and factors governing the abundance of native and invasive aquatic species is enhanced by long-term surveys.

  6. Adjuvants Affect Duckweed (Lemna minor) Control with Pelargonic Acid

    OpenAIRE

    Charles L. Webber III; James W. Shrefler; Taylor, Merritt J.

    2014-01-01

    Duckweeds (Lemna spp.) are small, free floating aquatic plants that flourish on stagnant or slow moving water surfaces throughout the world. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive tendencies make them formidable aquatic weeds, which when uncontrolled can result in oxygen depletion, fish kills, and death of submerged aquatic plants. Pelargonic acid is a fatty acid naturally occurring in many plant...

  7. Nutrients valorisation via duckweed-based wastewater treatment and aquaculture

    OpenAIRE

    El-Shafai, S.A.A.M.

    2004-01-01

    Development of a sustainable wastewater treatment scheme to recycle sewage nutrients and water in tilapia aquaculture was the main objective of this PhD research. Use of an Integrated UASB-duckweed ponds system for domestic wastewater treatment linked to tilapia aquaculture was investigated. The treatment system was efficiënt in organic matter removal during the entire year, while nitrogen, phosphorus and faecal coliform removal were negatively affected by the decline in temperat...

  8. Sequential disinfection of E. coli O157:H7 on shredded lettuce leaves by aqueous chlorine dioxide, ozonated water, and thyme essential oil

    Science.gov (United States)

    Singh, Nepal; Singh, Rakesh K.; Bhunia, Arun K.; Stroshine, Richard L.; Simon, James E.

    2001-03-01

    There have been numerous studies on effectiveness of different sanitizers for microbial inactivation. However, results obtained from different studies indicate that microorganism cannot be easily removed from fresh cut vegetables because of puncture and cut surfaces with varying surface topographies. In this study, three step disinfection approach was evaluated for inactivation of E. coli O157:H7 on shredded lettuce leaves. Sequential application of thyme oil, ozonated water, and aqueous chlorine dioxide was evaluated in which thyme oil was applied first followed by ozonated water and aqueous chlorine dioxide. Shredded lettuce leaves inoculated with cocktail culture of E. coli O157:H7 (C7927, EDL 933 and 204 P), were washed with ozonated water (15 mg/l for 10min), aqueous chlorine dioxide (10 mg/l,for 10min) and thyme oil suspension (0.1%, v/v for 5min). Washing of lettuce leaves with ozonated water, chlorine dioxide and thyme oil suspension resulted in 0.44, 1.20, and 1.46 log reduction (log10 cfu/g), respectively. However, the sequential treatment achieved approximately 3.13 log reductions (log10 cfu/g). These results demonstrate the efficacy of sequential treatments in decontaminating shredded lettuce leaves containing E. coli O157:H7.

  9. Evolution of Genome Size in Duckweeds (Lemnaceae)

    OpenAIRE

    Wenqin Wang; Kerstetter, Randall A.; Michael, Todd P.

    2011-01-01

    To extensively estimate the DNA content and to provide a basic reference for duckweed genome sequence research, the nuclear DNA content for 115 different accessions of 23 duckweed species was measured by flow cytometry (FCM) stained with propidium iodide as DNA stain. The 1C-value of DNA content in duckweed family varied nearly thirteen-fold, ranging from 150 megabases (Mbp) in Spirodela polyrhiza to 1,881?Mbp in Wolffia arrhiza. There is a continuous increase of DNA content in Spirodela, Lan...

  10. Response of duckweed to various concentrations of selenite.

    Science.gov (United States)

    Mechora, Špela; Stibilj, Vekoslava; Germ, Mateja

    2015-02-01

    The uptake of Se(IV) and its effects on the physiological and biochemical characteristics of duckweed (Lemna minor L.) have been studied. Duckweed plants were cultivated in controlled conditions for 7 weeks in different concentrations of Na selenite: 0.5, 1, 2, 5 (exposed 42 days) and 10 mg Se L(-1) (survived 7-21 days). The addition of 1 mg Se L(-1) did not negatively affect photochemical efficiency whilst respiratory potential increased in weeks 2-4 compared to control. The addition of 1 mg Se(IV) L(-1) increased the amount of chlorophyll a in weeks 3 and 4 and the amount of carotenoids in weeks 1, 3 and 5. Concentrations of 2 and 5 mg Se L(-1) negatively affected photochemical efficiency in weeks 3 and 4, and increased respiratory potential in comparison to the control in weeks 1-4, whilst beyond week 4, the respiratory potential decreased. Plants exposed to the highest concentration of Se(IV) had to be replaced twice during the experiment because they were dying. That was reflected in photochemical efficiency as well as in respiratory potential, which decreased in time. The content of Se in duckweed increased with the increasing concentration of Se: plants growing in 0.5 mg Se L(-1) contained 0.9 mg Se g(-1) DM and plants exposed to 5 mg Se L(-1) contained 5.8 mg Se g(-1) DM. The group of plants exposed to 10 mg Se L(-1) for 21 days contained 19.5 mg Se g(-1) DM. Our study revealed that duckweed absorbed high amount of Se(IV) from the water. PMID:25028325

  11. Evaluation of the potential of Pistia stratiotes L. (water lettuce) for bioindication and phytoremediation of aquatic environments contaminated with arsenic.

    Science.gov (United States)

    Farnese, F S; Oliveira, J A; Lima, F S; Leão, G A; Gusman, G S; Silva, L C

    2014-08-01

    Specimens of Pistia stratiotes were subjected to five concentrations of arsenic (As) for seven days. Growth, As absorption, malondialdehyde (MDA) content, photosynthetic pigments, enzymatic activities, amino acids content and anatomical changes were assessed. Plant arsenic accumulation increased with increasing metalloid in the solution, while growth rate and photosynthetic pigment content decreased. The MDA content increased, indicating oxidative stress. Enzymatic activity and amino acids content increased at the lower doses of As, subsequently declining in the higher concentrations. Chlorosis and necrosis were observed in the leaves. Leaves showed starch accumulation and increased thickness of the mesophyll. In the root system, there was a loss and darkening of roots. Cell layers formed at the insertion points on the root stems may have been responsible for the loss of roots. These results indicate that water lettuce shows potential for bioindication and phytoremediation of As-contaminated aquatic environments. PMID:25627371

  12. Stress responses of duckweed (Lemna minor L.) and water velvet (Azolla filiculoides Lam.) to anionic surfactant sodium-dodecyl-sulphate (SDS).

    Science.gov (United States)

    Forni, C; Braglia, R; Harren, F J M; Cristescu, S M

    2012-04-01

    Surfactants are used for several purposes and recently they have attracted the attention for their ability to modify the behavior of other preexistent or co-disposed contaminants, although their use or discharge in wastewaters can represent a real or potential risk for the environment. Lemna minor L. and Azolla filiculoides Lam. are floating aquatic macrophytes, very effective in accumulating several pollutants including sodium dodecyl sulphate (SDS). In this work we evaluated the effects of SDS on these species by determining the stress ethylene production via laser-based trace gas detection, and the activities of enzymes involved in stress response, such as guaiacol peroxidase (G-POD), phenylalanine ammonia-lyase (PAL) and polyphenol-oxidase (PPO). Phenolics content was also determined. The macrophytes were treated with different concentrations of SDS for one week. SDS affected duckweed enzymatic activities and phenol content. While in the fern phenolics amount, PAL, G-POD and PPO activities were not affected by SDS except for 100 ppm SDS, the only concentration that was taken up and not completely degraded. Stress ethylene production was induced only in the fern treated with 50 and 100 ppm SDS. PMID:22277247

  13. Estimate of uptake and translocation of emerging organic contaminants from irrigation water concentration in lettuce grown under controlled conditions.

    Science.gov (United States)

    Hurtado, Carlos; Domínguez, Carmen; Pérez-Babace, Lorea; Cañameras, Núria; Comas, Jordi; Bayona, Josep M

    2016-03-15

    The widespread distribution of emerging organic contaminants (EOCs) in the water cycle can lead to their incorporation in irrigated crops, posing a potential risk for human consumption. To gain further insight into the processes controlling the uptake of organic microcontaminants, Batavia lettuce (Lactuca sativa) grown under controlled conditions was watered with EOCs (e.g., non-steroidal anti-inflammatories, sulfonamides, ?-blockers, phenolic estrogens, anticonvulsants, stimulants, polycyclic musks, biocides) at different concentrations (0-40?gL(-1)). Linear correlations were obtained between the EOC concentrations in the roots and leaves and the watering concentrations for most of the contaminants investigated. However, large differences were found in the root concentration factors ( [Formula: see text] =0.27-733) and leaf translocation concentration factors ( [Formula: see text] =0-3) depending on the persistence of the target contaminants in the rhizosphere and the specific physicochemical properties of each one. With the obtained dataset, a simple predictive model based on a linear regression and the root bioconcentration and translocation factors can be used to estimate the concentration of the target EOCs in leaves based on the dose supplied in the irrigation water or the soil concentration. Finally, enantiomeric fractionation of racemic ibuprofen from the initial spiking mixture suggests that biodegradation mainly occurs in the rhizosphere. PMID:26651071

  14. Crescimento, consumo hídrico e composição mineral de alface cultivada em hidroponia com águas salinas / Growth, water consumption and mineral composition of lettuce in hydroponic system with saline water

    Scientific Electronic Library Online (English)

    Dalva, Paulus; Eloi, Paulus; Gilmar Antônio, Nava; Cláudia Andrade, Moura.

    2012-02-01

    Full Text Available Objetivou-se, com este trabalho, avaliar o crescimento, o consumo hídrico e a extração de nutrientes, por alface (Lactuca sativa L.) em sistema hidropônico NFT (fluxo laminar de nutrientes), com a utilização de águas salinas no preparo da solução nutritiva e reposição da lâmina diária evapotranspira [...] da. Foram conduzidos dois experimentos, em ambiente protegido. O delineamento experimental foi em blocos ao acaso, sendo estudados os efeitos de cinco níveis de salinidade da água, utilizando-se NaCl. O aumento da salinidade da água reduziu, de forma linear, o crescimento e o consumo hídrico da alface. A salinidade reduziu a concentração de macronutrientes na parte aérea, mas não se observaram sintomas de deficiência nutricional. O rendimento (massa de matéria fresca da parte aérea) foi reduzido entre 6 e 6,5% por dS m-1, no primeiro e segundo cultivo, respectivamente. Os resultados obtidos em sistema de cultivo NFT podem indicar a possibilidade do uso da água salina como alternativa para produção de hortaliças, para produtores que têm disponibilidade restrita de água doce, porém, com redução de produtividade. Abstract in english The objective of this study was to evaluate the growth, water consumption and extraction of nutrients of lettuce (Lactuca sativa L.) in a NFT (nutrient film technique) in hydroponic system using saline water. Two experiments were conducted in a protected environment. The experiment was arranged in a [...] completely randomized design with five replications and five levels of salinity in the irrigation water using NaCl. Increasing water salinity reduced the growth and water consumption of lettuce linearly. The salinity reduced the macronutrient concentration, but symptoms of nutritional deficiency were not observed. The lettuce yield (shoot fresh matter) was reduced by 6% and 6.5% per dS m¹, in the first and second crops, respectively. The results obtained in the NFT system indicate the possibility of using saline water as an alternative for the production of vegetables by farmers who have freshwater restriction, although with a reduction in the yield.

  15. A comparative study of digital RT-PCR and RT-qPCR for quantification of Hepatitis A virus and Norovirus in lettuce and water samples.

    Science.gov (United States)

    Coudray-Meunier, Coralie; Fraisse, Audrey; Martin-Latil, Sandra; Guillier, Laurent; Delannoy, Sabine; Fach, Patrick; Perelle, Sylvie

    2015-05-18

    Sensitive and quantitative detection of foodborne enteric viruses is classically achieved by quantitative RT-PCR (RT-qPCR). Recently, digital PCR (dPCR) was described as a novel approach to genome quantification without need for a standard curve. The performance of microfluidic digital RT-PCR (RT-dPCR) was compared to RT-qPCR for detecting the main viruses responsible for foodborne outbreaks (human Noroviruses (NoV) and Hepatitis A virus (HAV)) in spiked lettuce and bottled water. Two process controls (Mengovirus and Murine Norovirus) were used and external amplification controls (EAC) were added to examine inhibition of RT-qPCR and RT-dPCR. For detecting viral RNA and cDNA, the sensitivity of the RT-dPCR assays was either comparable to that of RT-qPCR (RNA of HAV, NoV GI, Mengovirus) or slightly (around 1 log10) decreased (NoV GII and MNV-1 RNA and of HAV, NoV GI, NoV GII cDNA). The number of genomic copies determined by dPCR was always from 0.4 to 1.7 log10 lower than the expected numbers of copies calculated by using the standard qPCR curve. Viral recoveries calculated by RT-dPCR were found to be significantly higher than by RT-qPCR for NoV GI, HAV and Mengovirus in water, and for NoV GII and HAV in lettuce samples. The RT-dPCR assay proved to be more tolerant to inhibitory substances present in lettuce samples. This absolute quantitation approach may be useful to standardize quantification of enteric viruses in bottled water and lettuce samples and may be extended to quantifying other human pathogens in food samples. PMID:25725459

  16. Effect of nickel-stresses on uptake, pigments and antioxidative responses of water lettuce, Pistia stratiotes L.

    Science.gov (United States)

    Singh, Kavita; Pandey, S N

    2011-05-01

    Water lettuce plants were exposed to various concentrations (0, 0.01,0.1, 1.0 and 10.0 ppm) of nickel as nickel sulphate in nutrient medium. The effect of graded nickel (Ni +2) concentrations on visible symptoms of toxicity, pigments (chlorophyll a, b and total) and antioxidative attributes were evaluated. Plants exposed to high nickel (1.0 and 10.0 ppm) showed visible toxicity symptoms, such as wilting, chlorosis in young leaves, browning of root tips and broken off roots, observed at 6 days after treatment. Nickel was accumulated more in root (863.3 microg g-1 dry weight) than leaves (116.2 microg g-1 dry weight) at 6 days of treatment. Nickel exposure decreased chlorophyll a, b and total chlorophyll contents. Relative water content decreased at high nickel (1.0 and 10.0 ppm).Antioxidants, such as proline content and peroxidase activity increased with increase in nickel concentrations, whereas, other carotenoids and protein contents at 1.0 ppm and activity of catalase at 10 ppm of nickel were decreased. The low level of nickel stimulates photosynthetic pigments and antioxidative attributes. The study may be helpful in phytoremedial strategies and biological indication of nickel toxicity in aquatic plants. PMID:22167955

  17. Duckweed control with over-the-top application of pelargonic acid

    Science.gov (United States)

    Duckweeds (Lemna spp.) are small, free floating, aquatic plants that flourish on stagnant, or slow moving, water surfaces throughout the continental U.S. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive tendenci...

  18. Effects of A200 superabsorbent, bentonite and water stress on physiological traits and vitamin C of lettuce under greenhouse cultivation

    Directory of Open Access Journals (Sweden)

    2015-06-01

    Full Text Available Water stress is a global crisis and is considered a serious threat for agriculture. Superabsorbent polymers, through improving soil physical conditions, prevent moisture stress in arid and semi-arid areas. To evaluate the effects of a natural superabsorbent (bentonite and a synthetic superabsorbent (A200 on growth of lettuce, a factorial experiment in a completely randomized design with four replications was conducted. The amount of each superabsorbent at 3 levels (0, 0.15 and 0.3% w/w and 2 levels of water stress (60 and 100% of field capacity were tested. The results showed that in 100% of field capacity treatment, leaf relative water content, chlorophyll index and stomatal conductance were more than 60% of field capacity treatment. Electrolyte leakage, vitamin C, total soluble solids and chlorophyll b were higher in 60% of field capacity treatment. Application of 0.3% bentonite decreased electrolyte leakage, vitamin C and soluble solids by 74, 19 and 31 percent, respectively, and increased relative water content, chlorophyll index, stomatal conductance and total chlorophyll content by 3, 2, 22 and 8 percent, respectively, relative to the control. While, application of 0.3% of superabsorbent A200 decreased electrolyte leakage, vitamin C and soluble solids by 28, 18 and 37 percent, respectively, and increased relative water content, chlorophyll index, stomatal conductance and total chlorophyll content by 6, 32, 25 and 42 percent, respectively, as compared to the control treatment. These results indicated that bentonite can reduce the negative impacts of drought stress as much as artificial superabsorbent.

  19. Manipulating duckweed through genome duplication.

    Science.gov (United States)

    Vunsh, R; Heinig, U; Malitsky, S; Aharoni, A; Avidov, A; Lerner, A; Edelman, M

    2015-01-01

    Significant inter- and intraspecific genetic variation exists in duckweed, thus the potential for genome plasticity and manipulation is high. Polyploidy is recognised as a major mechanism of adaptation and speciation in plants. We produced several genome-duplicated lines of Landoltia punctata (Spirodela oligorrhiza) from both whole plants and regenerating explants using a colchicine-based cocktail. These lines stably maintained an enlarged frond and root morphology. DNA ploidy levels determined by florescence-activated cell sorting indicated genome duplication. Line A4 was analysed after 75 biomass doublings. Frond area, fresh and dry weights, rhizoid number and length were significantly increased versus wild type, while the growth rate was unchanged. This resulted in accumulation of biomass 17-20% faster in the A4 plants. We sought to determine if specific differences in gene products are found in the genome duplicated lines. Non-targeted ultra performance LC-quadrupole time of flight mass spectrometry was employed to compare some of the lines and the wild type to seek identification of up-regulated metabolites. We putatively identified differential metabolites in Line A65 as caffeoyl hexoses. The combination of directed genome duplication and metabolic profiling might offer a path for producing stable gene expression, leading to altered production of secondary metabolites. PMID:25040392

  20. Lettuce contact allergy

    DEFF Research Database (Denmark)

    Paulsen, Evy; Andersen, Klaus E

    2015-01-01

    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 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 re...

  1. Estratégias de uso de água salobra na produção de alface em hidroponia NFT / Strategies for use of brackish water in NFT hydroponic lettuce production

    Scientific Electronic Library Online (English)

    Márcio S., Alves; Tales M., Soares; Luana T., Silva; Joseane P., Fernandes; Mariana L. A., Oliveira; Vital P. S., Paz.

    2011-05-01

    Full Text Available Plantas de alface crespa 'Verônica' foram cultivadas em condições hidropônicas, objetivando avaliar três diferentes estratégias de emprego de águas salobras: 1) águas salobras para reposição das perdas por evapotranspiração (ETc) e água doce para o preparo da solução nutritiva (SN); 2) águas salobra [...] s para o preparo da SN e água doce para reposição da ETc; 3) águas salobras para o preparo da SN e reposição da ETc. Os níveis de salinidade da água foram obtidos pela adição de NaCl à água doce (0,27 dS m-1): 1,45; 2,51; 3,6; 5,41 e 7,5 dS m-1. O experimento foi conduzido em quatro blocos aleatorizados, com quatro repetições por tratamento. Uma estrutura de pesquisa foi construída com 72 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT). O uso de água salobra apenas para repor a ETc não produziu efeito sobre a produção da alface. Por outro lado, o uso de águas salobras para o preparo da SN e água doce para reposição da ETc, reduziu o rendimento da alface (massa de matéria fresca da parte aérea) em 4,99% por (dS m-1). O rendimento foi reduzido em 7% por dS m-1 quando águas salobras foram usadas tanto para o preparo da SN quanto para reposição da ETc. Apesar da redução linear da produção da alface com o aumento da salinidade da água, sintomas depreciativos para a qualidade da alface hidropônica não foram registrados. Abstract in english Plants of crisphead lettuce cv. 'Verônica' were grown under hydroponic conditions aiming to evaluate three different strategies of brackish waters utilization: 1) brackish waters to replace the evapotranspiration loss (ETc) and fresh water to prepare nutrient solution (NS); 2) brackish waters to pre [...] pare NS and fresh water to replace the ETc; 3) brackish waters to prepare NS and replace ETc. The levels of water salinity were obtained by addition of NaCl to fresh water (0.27 dS m-1): 1.45; 2.51; 3.6; 5.41 and 7.5 dS m-1. The experiment was conducted in randomized blocks with four replications per treatment. A research structure was built with 72 experimental units which simulate the nutrient film technique (NFT). The use of brackish water only to replace the ETc did not affect the lettuce yield. On the other hand, the use of brackish waters to prepare NS, and fresh water to replace the ETc loss, reduce the lettuce yield (shoot fresh matter) by 4.99% per (dS m-1). The lettuce yield was reduced by 7% per dS m-1 as brackish water was used to prepare NS and replace ETc loss. Despite the linear decline of lettuce yield as the water salinity increased, depreciative symptoms for quality of hydroponic lettuce were not registered.

  2. Estratégias de uso de água salobra na produção de alface em hidroponia NFT Strategies for use of brackish water in NFT hydroponic lettuce production

    Directory of Open Access Journals (Sweden)

    Márcio S. Alves

    2011-05-01

    Full Text Available Plantas de alface crespa 'Verônica' foram cultivadas em condições hidropônicas, objetivando avaliar três diferentes estratégias de emprego de águas salobras: 1 águas salobras para reposição das perdas por evapotranspiração (ETc e água doce para o preparo da solução nutritiva (SN; 2 águas salobras para o preparo da SN e água doce para reposição da ETc; 3 águas salobras para o preparo da SN e reposição da ETc. Os níveis de salinidade da água foram obtidos pela adição de NaCl à água doce (0,27 dS m-1: 1,45; 2,51; 3,6; 5,41 e 7,5 dS m-1. O experimento foi conduzido em quatro blocos aleatorizados, com quatro repetições por tratamento. Uma estrutura de pesquisa foi construída com 72 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT. O uso de água salobra apenas para repor a ETc não produziu efeito sobre a produção da alface. Por outro lado, o uso de águas salobras para o preparo da SN e água doce para reposição da ETc, reduziu o rendimento da alface (massa de matéria fresca da parte aérea em 4,99% por (dS m-1. O rendimento foi reduzido em 7% por dS m-1 quando águas salobras foram usadas tanto para o preparo da SN quanto para reposição da ETc. Apesar da redução linear da produção da alface com o aumento da salinidade da água, sintomas depreciativos para a qualidade da alface hidropônica não foram registrados.Plants of crisphead lettuce cv. 'Verônica' were grown under hydroponic conditions aiming to evaluate three different strategies of brackish waters utilization: 1 brackish waters to replace the evapotranspiration loss (ETc and fresh water to prepare nutrient solution (NS; 2 brackish waters to prepare NS and fresh water to replace the ETc; 3 brackish waters to prepare NS and replace ETc. The levels of water salinity were obtained by addition of NaCl to fresh water (0.27 dS m-1: 1.45; 2.51; 3.6; 5.41 and 7.5 dS m-1. The experiment was conducted in randomized blocks with four replications per treatment. A research structure was built with 72 experimental units which simulate the nutrient film technique (NFT. The use of brackish water only to replace the ETc did not affect the lettuce yield. On the other hand, the use of brackish waters to prepare NS, and fresh water to replace the ETc loss, reduce the lettuce yield (shoot fresh matter by 4.99% per (dS m-1. The lettuce yield was reduced by 7% per dS m-1 as brackish water was used to prepare NS and replace ETc loss. Despite the linear decline of lettuce yield as the water salinity increased, depreciative symptoms for quality of hydroponic lettuce were not registered.

  3. 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. PMID:26289653

  4. Lettuce contact allergy

    DEFF Research Database (Denmark)

    Paulsen, Evy; Andersen, Klaus E

    2015-01-01

    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 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-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.

  5. Status of duckweed genomics and transcriptomics.

    Science.gov (United States)

    Wang, W; Messing, J

    2015-01-01

    Duckweeds belong to the smallest flowering plants that undergo fast vegetative growth in an aquatic environment. They are commonly used in wastewater treatment and animal feed. Whereas duckweeds have been studied at the biochemical level, their reduced morphology and wide environmental adaption had not been subjected to molecular analysis until recently. Here, we review the progress that has been made in using a DNA barcode system and the sequences of chloroplast and mitochondrial genomes to identify duckweed species at the species or population level. We also review analysis of the nuclear genome sequence of Spirodela that provides new insights into fundamental biological questions. Indeed, reduced gene families and missing genes are consistent with its compact morphogenesis, aquatic floating and suppression of juvenile-to-adult transition. Furthermore, deep RNA sequencing of Spirodela at the onset of dormancy and Landoltia in exposure of nutrient deficiency illustrate the molecular network for environmental adaption and stress response, constituting major progress towards a post-genome sequencing phase, where further functional genomic details can be explored. Rapid advances in sequencing technologies could continue to promote a proliferation of genome sequences for additional ecotypes as well as for other duckweed species. PMID:24995947

  6. Characterisation of circadian rhythms of various duckweeds.

    Science.gov (United States)

    Muranaka, T; Okada, M; Yomo, J; Kubota, S; Oyama, T

    2015-01-01

    The plant circadian clock controls various physiological phenomena that are important for adaptation to natural day-night cycles. Many components of the circadian clock have been identified in Arabidopsis thaliana, the model plant for molecular genetic studies. Recent studies revealed evolutionary conservation of clock components in green plants. Homologues of clock-related genes have been isolated from Lemna gibba and Lemna aequinoctialis, and it has been demonstrated that these homologues function in the clock system in a manner similar to their functioning in Arabidopsis. While clock components are widely conserved, circadian phenomena display diversity even within the Lemna genus. In order to survey the full extent of diversity in circadian rhythms among duckweed plants, we characterised the circadian rhythms of duckweed by employing a semi-transient bioluminescent reporter system. Using a particle bombardment method, circadian bioluminescent reporters were introduced into nine strains representing five duckweed species: Spirodela polyrhiza, Landoltia punctata, Lemna gibba, L. aequinoctialis and Wolffia columbiana. We then monitored luciferase (luc+) reporter activities driven by AtCCA1, ZmUBQ1 or CaMV35S promoters under entrainment and free-running conditions. Under entrainment, AtCCA1::luc+ showed similar diurnal rhythms in all strains. This suggests that the mechanism of biological timing under day-night cycles is conserved throughout the evolution of duckweeds. Under free-running conditions, we observed circadian rhythms of AtCCA1::luc+, ZmUBQ1::luc+ and CaMV35S::luc+. These circadian rhythms showed diversity in period length and sustainability, suggesting that circadian clock mechanisms are somewhat diversified among duckweeds. PMID:24942699

  7. BIOSORPTIVE REMOVAL OF HEAVY METALS FROM WASTEWATER USING DUCKWEED

    Directory of Open Access Journals (Sweden)

    Ankita Suhag

    2011-09-01

    Full Text Available Water pollution has been recognized as a problem for decades. The use of heavy metals in industries and their regular mining increases their concentration in water bodies. Unlike organic compounds, metals cannot degrade, and therefore effective cleanup requires their immobilization to reduce or remove toxicity. A few conventional methods employed to remove heavy metals from wastewater are expensive, require skilled labors and maintenance. Therefore, the use of aquatic plants has come up since the last few decades. Duckweed is onesuch plant employed as a biosorbent and has been considered a better alternative than any other aquatic plant because of high tolerance to cold than water hyacinth, more easilyharvested than algae, capable of rapid growth (0.1 to 0.5 g g-1 day-1 and small size of plant. This study aims to determine the suitability of this plant for biosorbing toxic heavy metalscommonly found in industrial wastewater, domestic wastewater, and seepage water.

  8. Comprehensive Study Of Duckweed Cultivation And Growth Conditions Under Controlled Eutrophication

    OpenAIRE

    Bartošová Alica; Sirotiak Maroš; Fiala Jozef

    2015-01-01

    The paper discussed the issue of eutrophication. The most conspicuous effect of eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality. Nutrient concentration, temperature and pH of the water largely influence the growth rate and composition of duckweed in general, but it can be said that the temperature and solar irradiation are the most important factors. In order to compare the rate of biomass increase of duck...

  9. The prospects of duckweed culturing in alleviating poverty in Nigeria

    OpenAIRE

    Adesina, G.O.; Daddy, F.; Mohammed, A H; Uka, P.

    2005-01-01

    Duckweed is the smallest of all flowering plants and the plant double its mass in less than 2 days under ideal environmental conditions. Dry matter of duckweed contains between 35-45% crude protein. Moreover, the introduction of the plant to feed mill industries as a source of protein and binder supplement for pelleted fish feeds makes it of economic value. Duckweed has great potential if cultivation is encouraged in Nigeria, as this will also provide a good employment opportunity for larger ...

  10. Role of Cellulose and Colanic Acid in Attachment of Shiga Toxin-Producing Escherichia coli to Lettuce and Spinach in Different Water Hardness Environments.

    Science.gov (United States)

    Lee, Chi-Ching; Chen, Jinru; Frank, Joseph F

    2015-08-01

    This study investigated the role of extracellular cellulose production by Shiga toxin-producing Escherichia coli (STEC) on attachment to lettuce and spinach in different water hardness environments. Two cellulose-producing wild-type STEC strains, 19 (O5:H-) and 49 (O103:H2), and their cellulose-deficient derivatives were used. Strain 49 also produced colanic acid as a constituent of its extracellular polymeric substances. Attached cells were determined by plate counts on the surface and cut edge of the leaves after an attachment period of 2 h at 4°C. Hydrophobicity and surface charge of the cells were determined. Strain 49 attached at levels 0.3 and 0.6 log greater to the surface and 0.9 and 0.4 log greater to the cut edges of spinach compared to strain 19 for both wild-type and cellulose-deficient cells (P > 0.05). Cellulose-producing cells attached more to the surface of lettuce but not of spinach than did cellulose-deficient cells. However, more cellulose-deficient cells attached (at levels 0.66 and 0.3 log greater) to the cut edge of lettuce (representing damaged tissue) than did cellulose-proficient cells (P > 0.05). Colanic acid production was associated with cell surfaces of low hydrophobicity. There was a decreasing level of attachment for the colanic acid-producing strain when water hardness increased from 200 to 1,000 pm on lettuce and spinach leaf surfaces, but no effects were seen for other cells. This decreased attachment was associated with a more negative surface charge. Cells that produced colanic acid were less hydrophobic and exhibited greater attachment to the surface and cut edge of spinach when compared to cells that did not produce colanic acid. Attachment of colanic acid-producing cells to leafy green surfaces was enhanced in higher water hardness environments. These data indicate that attachment of E. coli O157:H7 to leafy greens involves multiple mechanisms that are influenced by the type of leafy green, damage to the leaf, and the water hardness environment. PMID:26219358

  11. Lettuce contact allergy

    DEFF Research Database (Denmark)

    Paulsen, Evy; Andersen, Klaus E

    2015-01-01

    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...... 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...

  12. Combinação de águas doce e salobra para produção de alface hidropônica / Combination of fresh and brackish waters for hydroponic lettuce production

    Scientific Electronic Library Online (English)

    Tales M., Soares; Sergio N., Duarte; Ênio F. F., Silva; Cristiano A., Jorge.

    2010-07-01

    Full Text Available Plantas de alface crespa cv. Verônica foram cultivadas em condição hidropônica objetivando-se avaliar dois tipos de emprego combinado de águas doce e salobras, quais sejam: usar as águas salobras para preparar a solução nutritiva (SN) e a água doce para repor a evapotranspiração da cultura (ETc) (Ex [...] perimento I) e usar a água doce para preparar a SN e as salobras para a reposição da ETc (Experimento II). Uma estrutura de pesquisa com 40 parcelas que simulam a técnica do fluxo laminar de nutrientes (NFT) foi construída. Os níveis de salinidade da água testados foram: 0,585; 1,17; 1,755; 2,925 e 4,095 g L-1 de NaCl. A salinidade diminuiu a produtividade da alface (massa de matéria fresca da parte aérea) em 10,9 e 3,91% para cada acréscimo unitário na salinidade da água (g L-1 de NaCl), considerando-se os Experimentos I e II, respectivamente. De acordo com os resultados obtidos com os dois tipos de combinação de águas doce e salobras, o uso de águas salobras para repor a ETc pode aumentar a produtividade da alface em comparação com o uso dessas águas para preparar a SN. Abstract in english Plants of crisphead lettuce cv. Verônica were grown under hydroponic conditions aiming to evaluate two types of combination of brackish and fresh waters: using the brackish waters to prepare nutrient solution (NS) and fresh water to replace the evapotranspiration loss (ETc) (Experiment I) and using [...] the fresh water to prepare NS and the brackish waters to replace the ETc loss (Experiment II). A research structure was built up with 40 experimental units which simulated the nutrient film technique (NFT). The levels of water salinity were 0.585; 1.17; 1.755; 2.925 and 4.095 g L-1 NaCl. The lettuce yield (fresh shoot matter) decreased 10.9 and 3.91% for each unit increase in water salinity (g L-1 NaCl) in Experiments I and II, respectively. According to results obtained with the two types of combination of fresh and brackish waters, the use of brackish waters to replace ETc loss may increase the lettuce yield in comparison to using these waters to prepare the NS.

  13. Mutations in Lettuce Improvement

    OpenAIRE

    Beiquan Mou

    2011-01-01

    Lettuce is a major vegetable in western countries. Mutations generated genetic variations and played an important role in the domestication of the crop. Many traits derived from natural and induced mutations, such as dwarfing, early flowering, male sterility, and chlorophyll deficiency, are useful in physiological and genetic studies. Mutants were also used to develop new lettuce products including miniature and herbicide-tolerant cultivars. Mutant analysis was critical in lettuce genomic stu...

  14. Comprehensive Study Of Duckweed Cultivation And Growth Conditions Under Controlled Eutrophication

    Science.gov (United States)

    Bartošová, Alica; Sirotiak, Maroš; Fiala, Jozef

    2015-06-01

    The paper discussed the issue of eutrophication. The most conspicuous effect of eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality. Nutrient concentration, temperature and pH of the water largely influence the growth rate and composition of duckweed in general, but it can be said that the temperature and solar irradiation are the most important factors. In order to compare the rate of biomass increase of duckweed biomass in natural conditions and in a laboratory grown sample was analysed by spectrophotometric methods in UV/VIS region (Spectrophotometer GENESYSTM) for the selected nutrients such as ammonium, ammonium nitrogen, nitrite, nitrate, and phosphate.

  15. Comprehensive Study Of Duckweed Cultivation And Growth Conditions Under Controlled Eutrophication

    Directory of Open Access Journals (Sweden)

    Bartošová Alica

    2015-06-01

    Full Text Available The paper discussed the issue of eutrophication. The most conspicuous effect of eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality. Nutrient concentration, temperature and pH of the water largely influence the growth rate and composition of duckweed in general, but it can be said that the temperature and solar irradiation are the most important factors. In order to compare the rate of biomass increase of duckweed biomass in natural conditions and in a laboratory grown sample was analysed by spectrophotometric methods in UV/VIS region (Spectrophotometer GENESYSTM for the selected nutrients such as ammonium, ammonium nitrogen, nitrite, nitrate, and phosphate.

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

    International Nuclear Information System (INIS)

    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. NEW METHOD FOR DETERMINING EFFLUENT TOXICITY USING DUCKWEED (LEMNA MINOR)

    Science.gov (United States)

    Duckweed (Lemna minor), a small vascular plant, grows rapidly, is sensitive to a wide variety of toxicants and is easy to culture. ethod is described that measures duckweed frond growth and chlorophyll levels as indicators of growth inhibition. he method requires a small testing ...

  18. Nutrient removal from swine lagoon effluent by duckweed

    Energy Technology Data Exchange (ETDEWEB)

    Bergmann, B.A.; Cheng, J.; Classen, J.; Stomp, A.M.

    2000-04-01

    Three duckweed geographic isolates were grown on varying concentrations of swine lagoon effluent in a greenhouse to determine their ability to remove nutrients from the effluent. Duckweed biomass was harvested every other day over a 12-day period. Duckweed biomass production, nutrient loss from the swine lagoon effluent, and nutrient content of duckweed biomass were used to identify effluent concentrations/geographic isolate combinations that are effective in terms of nutrient utilization from swine lagoon effluent and production of healthy duckweed biomass. When Lemna minor geographic isolate 8627 was grown on 50% swine lagoon effluent, respective losses of TKN, NH{sub 3}-N, TP, OPO{sub 4}-P, TOC, K, Cu, and Zn were 83, 100, 49, 31, 68, 21, 28 and 67%.

  19. Productivity of duckweed (Lemna minor) as alternative forage feed for livestock in different light intensities

    OpenAIRE

    Uti Nopriani; PDMH Karti; Iwan Prihantoro

    2015-01-01

    Duckweed (Lemna minor) is a small aquatic plant that grow and float in water and spread extensively. Lemna minor is potential as a source of high quality forage. This study aimed to determine optimal light intensity on Lemna minor to generate maximum productivity. Parameters observed were physical-biological and chemical characteristics of the media (pH value, temperature, cover area, decreased of media volume, BOD, COD, nitrate, nitrite and phosphate), plant growth acceleration (number of sh...

  20. Economic comparison of two application methods for potential organic control of duckweed utilizing pelargonic acid as an aquatic herbicide

    Science.gov (United States)

    Duckweeds (Lemna spp.) are small, free floating, aquatic plants that flourish on stagnant or slow moving, water surfaces throughout the world. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive tendencies make the...

  1. Comparison of two application methods for potential organic control of duckweed utilizing pelargonic acid as an aquatic herbicide

    Science.gov (United States)

    Duckweeds (Lemna spp.) are small, free-floating, aquatic plants that flourish on stagnant or slow moving water surfaces throughout the world. Members of the genus are among the smallest flowering plants, providing food for fish and fowl. But their aggressive growth and invasive tendencies make them...

  2. Spectral Reflectance of Duckweed (Lemna Gibba L.) Fronds Exposed to Ethylene Glycol

    Science.gov (United States)

    Dong, Weijin; Carter, Gregory A.; Barber, John T.

    2001-01-01

    When duckweed (Lemna Gibba L.) fronds are exposed to ethylene glycol (EG) anatomy is altered, allowing an increase in water uptake that causes a darkening of frond appearance. Spectroradiometry was used to quantify changes in frond reflectance that occurred throughout the 400-850 nm spectrum under various EG concentrations and exposure times. The threshold concentration of EG at which a reflectance change could be detected was between 35 and 40 mM, approximately the same as by visual observation. EG-induced changes in frond reflectance were maximum at concentrations of 50 mM or greater. Reflectance changes were detectable within 24h of exposure to 100 mM EG,2-3 days prior to changes in frond appearance. The spectroradiometry of duckweed may serve as a rapid and sensitive technique for detection of ecosystem exposure to EG and perhaps other stress agents.

  3. Tapioca-starch wastewater toxicity characterized by Microtox and duckweed tests

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, Bengt-Erik (Stockholm University, Institute of Applied Environmental Research, Laboratory for Aquatic Ecotoxicology, Nykoeping (Sweden)); Triet, T. (University of Wisconsin, Institute for Environmental Studies, Madison, WI (United States))

    1994-12-01

    The toxicity of treated and untreated effluents from a tapioca (cassava), Manihot esculenta, starch industry in Thailand were tested on Microtox and a subtropical duckweed, Lemna aequinoctialis. Untreated samples demonstrated high toxicity in both tests, but also the treated effluent was toxic to duckweed. Aging of wastewater resulted in decreased toxicity which was partly correlated to cyanide content, but other (unidentified) components of the tapioca tubers also contribute to the toxicity. Considering the present findings and the fact that the majority of the tapioca starch industries in Southeast Asia have no effluent treatment there is a great risk for severe effects on crops (e.g. young stages of rice, vegetables, etc.) when the wastewater in traditional way is used for irrigation of farmland. Negative effects on local aquaculture and/or sensitive stages of valuable feral fish and crustacea populations in receiving water bodies can also be expected. 32 refs, 6 tabs

  4. Accumulation, elimination and retention of 99Tc by duckweed

    International Nuclear Information System (INIS)

    Accumulation dynamics of the long-lived fission product technetium (99Tc) in duckweed is studied. Duckweed serves as model for aquatic plants, because of its representative foliar uptake for 99Tc. 99Tc is irreversibly accumulated and distributed over cytoplasm, chloroplasts and mitochondria. Autoradiography showed that 99Tc was not transported to new biomass. Irreversible storage of 99Tc in plant biomass means that steady-state situations cannot be interpreted as a balance between uptake and elimination of 99Tc, but that 99Tc continuously builds up in each single duckweed plant and overall Tc concentrations are averaged over new biomass. (author)

  5. Comparative study of two bioassays with weakened duckweed and yeast treated with homeopathic preparations

    Directory of Open Access Journals (Sweden)

    Ursula Wolf

    2012-09-01

    Full Text Available In homeopathic basic research, the question as to the most adequate test systems and apt methodology is still open. This investigation examined the hypothesis that more complex organisms show stronger reactions to homeopathic remedies than less complex ones. We compared two Arsenic (As5+ stressed bioassays with duckweed (Lemna gibba, a multi-cellular autotrophic organism and yeast (Saccharomyces cerevisiae, a single-cellular heterotrophic organism regarding their response to homeopathic preparations [1]. For duckweed, growth rates of leaf area and leaf number were evaluated. For yeast, growth kinetics were determined by measuring slope, yield and Et50 (point in time when yield was half maximum of the sigmoid growth curve. The experiments with duckweed and yeast were performed in parallel (same day, same location and identical homeopathic preparations. After screening 17 substances, three homeopathic preparations (Arsenicum album, nosode, gibberellic acid were chosen for repeated experimental series [2]. Five independent experiments were conducted for each remedy with both organisms in parallel. Potency levels used were in the range of 17x–33x for duckweed and 17x–30x for yeast. To control for test system stability, systematic negative control experiments were conducted over the complete experimentation period. All experiments were blinded and randomized. The systematic negative control experiments did not yield any significant effects. Application of potentized Arsenicum album in the duckweed bioassay yielded the largest effects compared to water controls without remedies for the parameters leaf area and leaf number (p<0.001 [1, 3]. Potentized nosode preparations also had significant effects on duckweed's leaf area and leaf number (p<0.01. Growth was enhanced across all potency levels. In the yeast system the three homeopathic remedies did not show any significant effects on any growth curve parameter. The results obtained are in line with the hypothesis, that more complex organisms show stronger reactions to homeopathic remedies than less complex organisms. The test system with Lemna gibba, the stressor arsenic (As5+ and the homeopathic preparation Arsenicum album is suitable to further investigate factors influencing the quality and effects of potentized substances [4]. 1. Jäger T, Scherr C, Wolf U, Simon M, Heusser P, and Baumgartner S. Investigation of arsenic-stressed yeast (Saccharomyces cerevisiae as a bioassay in homeopathic basic research. ScientificWorldJournal. 2011 March 7;11:568-583. 2. Jäger T, Scherr C, Simon M, Heusser P, and Baumgartner S. Development of a test system for homeopathic preparations using impaired duckweed (Lemna gibba L.. J Altern Complement Med. 2011;17:315-323. 3. Jäger T, Scherr C, Simon M, Heusser P, and Baumgartner S. Effects of homeopathic arsenicum album, nosode, and gibberellic acid preparations on the growth rate of arsenic-impaired duckweed (Lemna gibba L.. ScientificWorldJournal. 2010 November 4;10:2112-2129. 4. Jäger T, Scherr C, Shah D, Majewsky V, Betti L, Trebbi G, et al. Use of homeopathic preparations in experimental studies with abiotically stressed plants. Homeopathy. 2011;100:275-287.

  6. 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

    2014-07-01

    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. PMID:24829142

  7. Influence of Salinity on Duckweed Growth and Duckweed Based Wastewater Treatment System

    OpenAIRE

    Sena Peace Hounkpe Wendeou; Martin Pepin Aina; Martin Crapper; Edmond Adjovi; Daouda Mama

    2013-01-01

    The growth of duckweed (Spirodela polyrrhiza) was investigated in an outdoor batch system under 15 different conductivities ranging from 200 ?S/cm to 3000 ?S/cm with average 110 ?mol/m2 daylight intensity. The growth was performed in an anaerobically treated domestic wastewater using an initial plants population of 50 fronds. Increase in Relative Growth Rate—RGR—(in terms of fresh weight and number of fronds) had a significant non-linear (polynomial) relationship with the conductivity. T...

  8. Effects of Homeopathic Arsenicum Album, Nosode, and Gibberellic Acid Preparations on the Growth Rate of Arsenic-Impaired Duckweed (Lemna gibba L.)

    OpenAIRE

    Tim Jüger; Claudia Scherr; Meinhard Simon; Peter Heusser; Stephan Baumgartner

    2010-01-01

    This study evaluated the effects of homeopathically potentized Arsenicum album, nosode, and gibberellic acid in a bioassay with arsenic-stressed duckweed (Lemna gibba L.). The test substances were applied in nine potency levels (17x, 18x, 21x–24x, 28x, 30x, 33x) and compared with controls (unsuccussed and succussed water) regarding their influence on the plant’s growth rate. Duckweed was stressed with arsenic(V) for 48 h. Afterwards, plants grew in either potentized substances or water contro...

  9. Nitrogen Fixation (Acetylene Reduction) Associated with Duckweed (Lemnaceae) Mats

    OpenAIRE

    Zuberer, D. A.

    1982-01-01

    Duckweed (Lemnaceae) mats in Texas and Florida were investigated, using the acetylene reduction assay, to determine whether nitrogen fixation occurred in these floating aquatic macrophyte communities. N2-fixing microorganisms were enumerated by plating or most-probable-number techniques, using appropriate N-free media. Results of the investigations indicated that substantial N2-fixation (C2H2) was associated with duckweed mats in Texas and Florida. Acetylene reduction values ranged from 1 to ...

  10. The Ecology and Palaeoecology of Diatom – Duckweed Relationships

    OpenAIRE

    Emson, D.

    2015-01-01

    This thesis focuses on the ecology and palaeoecology of diatom-duckweed relationships and utilises a combined experimental, ecological and palaeoecological approach. In particular, the study sought to determine the potential of the epiphytic diatom Lemnicola hungarica to be utilised as a proxy indicator of past dominance of duckweed (Lemna) in small ponds. To this end, contemporary sampling of epiphytic diatom assemblages from a variety of macrophytes (including multiple samples of free-float...

  11. The strength of limiting factors for duckweed during algal competition

    OpenAIRE

    Szabo, S.; Roijackers, R.M.M.; Scheffer, M.; Borics, G.

    2005-01-01

    Duckweed (Lemna gibba) growth was found to be strongly reduced by unicellular green algae (Scenedesmus conspicua, Chlorella sp., Chlamydomonas sp.) in indoor experiments. These algae reduced N, P, Fe and Mn concentrations of the medium drastically, moreover they increased the pH beyond 10. Subsequent additions of nutrients and pH neutralisation removed the growth inhibition of duckweed. This growth inhibition is, therefore, concluded to be due to pH increase and N, P and trace element (Fe, Mn...

  12. NITRATE AND SODIUM CONTAMINATION IN PERCOLATED WATER AND LEAF TISSUE IN LETTUCE CROP IRRIGATED WITH DOMESTIC SEWAGE WATER = CONTAMINAÇÃO POR NITRATO E SÓDIO DA ÁGUA PERCOLADA E DA PLANTA DE ALFACE IRRIGADA COM ÁGUA RESIDUÁRIA

    Directory of Open Access Journals (Sweden)

    João Antonio Galbiatti

    2004-01-01

    Full Text Available With the objective of characterizing and simulating the contamination of the percolated water in the soil, were analyzed lettuce crops fertilized with organic and mineral compounds and irrigated along furrows with residual water contaminated by total and fecal coliforms that originated from the dilution of domestic sewers with treated water. The experiment was conducted using thirty 500L amianthus boxes with a surface area of 1 m2 per box filled with sifted soil with a bottom layer of broken stones, 10cm thick. Three lettuce crops were used. The incorporation of organic and mineral fertilizers occurred during the first and third crops. Four irrigation furrows were used, which resulted in five rows of planted lettuce. Collectors of percolated water were made using ½ inch plastic tubes, sawed length-wise and covered with a sieve, and were installed at depths of 15 and 30 cm. A water collector was placed at 60cm depth of at the bottom of the boxes, and remained closed except for when collecting the two water samples taken during each crop cycle: 15 days after plantingthe lettuce seedlings and right before harvesting the lettuce. Chemical, physical and bacteriological analyses of the water collected at depth were carried out. The average concentration of nitrate and sodium in the three crops is indicative that feathers ofcontamination move slowly at depth in agricultural soils and in areas of organic and inorganic residue deposition. The microbial analyses of the water collected from the lower layer at a depth of 60 cm did not show contamination from fecal coliforms. = O trabalho foi desenvolvido no Centro de Estudos Ambientais/UNESP (CEA, em ambiente protegido, com o objetivo de se estudar os efeitos da fertilizaçãoorgânica, da fertilização mineral e da irrigação por sulcos, com água tratada e servida, em cultura da alface (Lactuca sativa L., observando-se a presença de nitrato (NO3- e sódio (Na+ no tecido foliar e bactérias coliformes totais (CT e coliformes fecais (CFna água percolada. As parcelas experimentais distribuídas em um delineamento experimental em blocos casualizados, constituíram-se de 30 caixas de amianto com volume de 500 L e área superficial de 1 m2 , preenchidas com solo previamente peneirado. Os tratamentos caracterizaram-se pela associação entre fertilizantes e água contaminada e tratada. Três cultivos de alface foram realizados. Coletores de água foram instalados a 15, 30 e 60 cm de profundidade. Duas coletas de água foram realizadas em cada cultivo, 15 dias após o transplante e uma na colheita, para verificar a presença de NO3-, Na+, CT e CF. Ao término de cada cultivo realizaram-se amostragens de tecido vegetal das folhas para análises químicas. As concentrações médias de NO3- e Na+ na solução percolada foram indicadoras de que plumas de contaminação avançaram lentamente em profundidade nos solos estudados. As análises de CF da água realizadas a 60 cm de profundidade não apresentaram contaminação. O tratamento fertilizado com cama de frango apresentou os maiores valores de NO3-.

  13. Distribution of carbofuran in a simulated fish/duckweed aquatic ecosystem

    International Nuclear Information System (INIS)

    The distribution, disappearance and residue of carbofuran labelled with 14C in a simulated fish/duckweed aquatic ecosystem have been studied. The results show that the carbofuran content in water decreases with time because of being absorbed by sludge of riverbed, eaten by fish and hydrolysis. The residual carbofuran in fish tissues is higher than that in water because of enrichment. There is much difference among carbofuran contents in various fish tissues, and the order in each tissue is found to be viscera>bone>muscle>gill>skin

  14. CHEMICAL AND PHYTOCHEMICAL COMPOSITION OF WILD LETTUCE (LAUNAEA TARAXACIFOLIA

    Directory of Open Access Journals (Sweden)

    ARAWANDE, JACOB OLALEKAN

    2013-01-01

    Full Text Available The study is focus on the proximate, mineral and phytochemical composition of Wild Lettuce and its extractive value in different solvents. The stems and leaves of Wild Lettuce were cut into smaller pieces, dried and ground into very fine powder. The powdery sample was analyzed for proximate and mineral constituents. The powdery sample was further subjected to extraction using acetone, chloroform, ethylacetate, methanol and water. The powdery sample as well as its solvent-extracts was screened for phytochemicals. It was found out that the powder sample contained flavonoid, phenol, oxalate, tannin, phytate and ascorbic acid but no alkaloid was found present. Methanol and water extracts contained all the phytochemicals present in the sample while only ascorbic acid was found in acetone and ethylacetate extracts. Chloroform extract contained phytate and ascorbic acid. Wild lettuce is very rich in nutrient and methanol as well as water is very effective in extracting bioactive materials of Wild Lettuce than ethylacetate, chloroform and acetone.

  15. Growing duckweed to recover nutrients from wastewaters and for production of fuel ethanol and animal feed

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jay J. [Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, North Carolina (United States); Stomp, Anne M. [Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina (United States)

    2009-01-15

    Lemnaceae or duckweed is an aquatic plant that can be used to recover nutrients from wastewaters. The grown duckweed can be a good resource of proteins and starch, and utilized for the production of value-added products such as animal feed and fuel ethanol. In the last eleven years we have been working on growing duckweed on anaerobically treated swine wastewater and utilizing the duckweed for fuel ethanol production. Duckweed strains that grew well on the swine wastewater were screened in laboratory and greenhouse experiments. The selected duckweed strains were then tested for nutrient recovery under laboratory and field conditions. The rates of nitrogen and phosphorus uptake by the duckweed growing in the laboratory and field systems were determined in the study. The mechanisms of nutrient uptake by the duckweed and the growth of duckweed in a nutrient-limited environment have been studied. When there are nutrients (N and P) available in the wastewater, duckweed takes the nutrients from the wastewater to support its growth and to store the nutrients in its tissue. When the N and P are completely removed from the wastewater, duckweed can use its internally stored nutrients to keep its growth for a significant period of time. A modified Monod model has been developed to describe nitrogen transport in a duckweed-covered pond for nutrient recovery from anaerobically treated swine wastewater. Nutrient reserve in the duckweed biomass has been found the key to the kinetics of duckweed growth. Utilization of duckweed for value-added products has a good potential. Using duckweed to feed animals, poultry, and fish has been extensively studied with promising results. Duckweed is also an alternative starch source for fuel ethanol production. Spirodela polyrrhiza grown on anaerobically treated swine wastewater was found to have a starch content of 45.8% (dry weight). Enzymatic hydrolysis of the duckweed biomass with amylases yielded a hydrolysate with a reducing sugar content corresponding to 50.9% of the original dry duckweed biomass. Fermentation of the hydrolysate using yeast gave an ethanol yield of 25.8% of the original dry duckweed biomass. These results indicate that the duckweed biomass can produce significant quantities of starch that can be readily converted into ethanol. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  16. Integrated analysis for a carbon- and water-constrained future: an assessment of drip irrigation in a lettuce production system in eastern Australia.

    Science.gov (United States)

    Maraseni, T N; Mushtaq, S; Reardon-Smith, K

    2012-11-30

    The Australian Government is meeting the challenge of water scarcity and climate change through significant on-farm infrastructure investment to increase water use efficiency and productivity, and secure longer term water supplies. However, it is likely that on-farm infrastructure investment will alter energy consumption and therefore generate considerable greenhouse gas (GHG) emissions, suggesting potential conflicts in terms of mitigation and adaptation policies. In particular, the introduction of a price on carbon may influence the extent to which new irrigation technologies are adopted. This study evaluated trade-offs between water savings, GHG emissions and economic gain associated with the conversion of a sprinkler (hand shift) irrigation system to a drip (trickle) irrigation system for a lettuce production system in the Lockyer Valley, one of the major vegetable producing regions in Australia. Surprisingly, instead of trade-offs, this study found positive synergies - a win-win situation. The conversion of the old hand-shift sprinkler irrigation system to a drip irrigation system resulted in significant water savings of almost 2 ML/ha, as well as an overall reduction in GHG emissions. Economic modelling, at a carbon price of $ 30/t CO(2)e, indicated that there was a net benefit of adoption of the drip irrigation system of about $ 4620/ML/year. We suggest priority should be given, in the implementation of on-farm infrastructure investment policy, to replacing older inefficient and energy-intensive sprinkler irrigation systems such as hand shift and roll-line. The findings of the study support the use of an integrated approach to avoid possible conflicts in designing national climate change mitigation and adaptation policies, both of which are being developed in Australia. PMID:22935628

  17. Elemental mapping of As and other elements in rootless duckweed Wolffia globosa

    International Nuclear Information System (INIS)

    Distribution of arsenic and the relationship with other elements in aquatic macrophytes Wolffia globosa is helpful in understanding mechanisms of arsenic accumulation and detoxification, which will be important for arsenic phytofiltration in contaminated water by aquatic macrophytes. In this paper, we study the distribution features of As and seven more elements in rootless duckweed Wolffia globosa by means of ?XRF. The results indicated that the distribution of As was similar to that of K, Mn and Zn while differs from that of Cu, Fe, Ni and Ca. (authors)

  18. Organic acid enhanced soil risk element (Cd, Pb and Zn) leaching and secondary bioconcentration in water lettuce (Pistia stratiotes L.) in the rhizofiltration process.

    Science.gov (United States)

    Veseý, Tomás; Tlustos, Pavel; Száková, Jirina

    2012-04-01

    The use of natural chelates to enhance risk element mobility combined with rhizofiltration by free floating macrophytes have not been thoroughly studied in recent years. The aim of this study was to investigate the efficiency of organic acids in soil by conducting flushing experiments to enhance the mobility of Cd, Pb, and Zn from soil to solution. In addition, the bioaccumulation of Cd, Pb, and Zn, in water lettuce (Pistia stratiotes L.) will be studied as they affect the biomass in the rhizofiltration process. The results revealed that citric and tartaric acids mobilised the highest amount of all risk elements. In comparison to control, citric acid mobilised 71%, 181%, and 112% of Cd, Pb, and Zn while tartaric acid mobilised 70%, 155%, and 135% of Cd, Pb, and Zn respectively. The bioconcentration factor was approximately 2-5 times higher for juvenile plants than mature plants for all treatments as well as for both parts (leaves and roots). The risk element translocation into aerial parts decreased with increased time. Juvenile and mature plants proved a high accumulation potential and a 3 week growth period was observed as a sufficient time period to remove more than 80% of Cd, Pb, and Zn. PMID:22567715

  19. Ecophysiological tolerance of duckweeds exposed to copper

    Energy Technology Data Exchange (ETDEWEB)

    Kanoun-Boule, Myriam [Centre for Functional Ecology, Department of Botany, University of Coimbra, Coimbra 3000-456 (Portugal)], E-mail: mkb@ci.uc.pt; Vicente, Joaquim A.F.; Nabais, Cristina [Centre for Functional Ecology, Department of Botany, University of Coimbra, Coimbra 3000-456 (Portugal); Prasad, M.N.V. [Department of Plant Sciences, University of Hyderabad, Hyderabad 500046 (India); Freitas, Helena [Centre for Functional Ecology, Department of Botany, University of Coimbra, Coimbra 3000-456 (Portugal)

    2009-01-18

    Although essential for plants, copper can be toxic when present in supra-optimal concentrations. Metal polluted sites, due to their extreme conditions, can harbour tolerant species and/or ecotypes. In this work we aimed to compare the physiological responses to copper exposure and the uptake capacities of two species of duckweed, Lemna minor (Lm(EC1)) and Spirodela polyrrhiza (SP), from an abandoned uranium mine with an ecotype of L. minor (Lm(EC2)) from a non-contaminated pond. From the lowest Cu concentration exposure (25 {mu}M) to the highest (100 {mu}M), Lm(EC2) accumulated higher amounts of copper than Lm(EC1) and SP. Dose-response curves showed that Cu content accumulated by Lm(EC2) increases linearly with Cu treatment concentrations (r{sup 2} = 0.998) whereas quadratic models were more suitable for Lm(EC1) and SP (r{sup 2} = 0.999 and r{sup 2} = 0.998 for Lm(EC1) and SP, respectively). A significant concentration-dependent decline of chlorophyll a (chl a) and carotenoid occurred as a consequence of Cu exposure. These declines were significant for Lm(EC2) exposed to the lowest Cu concentration (25 {mu}M) whereas for Lm(EC1) and SP a significant decrease in chl a and carotenoids was observed only at 50 and 100 {mu}M-Cu. Electric conductivity (EC) and malondialdehyde (MDA) content increased after Cu exposure, indicating oxidative stress. Significant increase of EC was observed in Lm(EC2) for all Cu concentrations whereas the increase for Lm(EC1) and SP became significant only after an exposure to 50 {mu}M-Cu. On the contrary, for Lm(EC1), SP, and Lm(EC2), MDA content significantly increased even at the lowest concentration. Protein content and catalase (CAT) activity showed a decrease with an increase in Cu concentration. For the species Lm(EC1) and SP, a significant effect of copper on CAT activity was observed only at the highest concentration (100 {mu}M-Cu) whereas, for Lm(EC2), this effect started to be significant after an exposure to 50 {mu}M-Cu. Superoxide dismutase (SOD) activity increased with increasing concentrations of Cu, with a very similar trend between the three populations of duckweed. However, due to the facts that enzyme activity is expressed as units of activity per gram of protein and that protein content decreased with Cu exposure, the increase in SOD activity might partly result from a relative increase of this enzyme inside the pool of proteins. Consequently, the results obtained in our experimental conditions strongly suggest that duckweed species from the uranium-polluted area have developed mechanisms to cope with metal toxicity and that this tolerance is based on the existence of protective mechanism to limit the metal uptake rather than on an enhancement of the antioxidative metabolism.

  20. Ecophysiological tolerance of duckweeds exposed to copper

    International Nuclear Information System (INIS)

    Although essential for plants, copper can be toxic when present in supra-optimal concentrations. Metal polluted sites, due to their extreme conditions, can harbour tolerant species and/or ecotypes. In this work we aimed to compare the physiological responses to copper exposure and the uptake capacities of two species of duckweed, Lemna minor (Lm(EC1)) and Spirodela polyrrhiza (SP), from an abandoned uranium mine with an ecotype of L. minor (Lm(EC2)) from a non-contaminated pond. From the lowest Cu concentration exposure (25 ?M) to the highest (100 ?M), Lm(EC2) accumulated higher amounts of copper than Lm(EC1) and SP. Dose-response curves showed that Cu content accumulated by Lm(EC2) increases linearly with Cu treatment concentrations (r2 = 0.998) whereas quadratic models were more suitable for Lm(EC1) and SP (r2 = 0.999 and r2 = 0.998 for Lm(EC1) and SP, respectively). A significant concentration-dependent decline of chlorophyll a (chl a) and carotenoid occurred as a consequence of Cu exposure. These declines were significant for Lm(EC2) exposed to the lowest Cu concentration (25 ?M) whereas for Lm(EC1) and SP a significant decrease in chl a and carotenoids was observed only at 50 and 100 ?M-Cu. Electric conductivity (EC) and malondialdehyde (MDA) content increased after Cu exposure, indicating oxidative stress. Significant increase of EC was observed in Lm(EC2) for all Cu concentrations whereas the increase for Lm(EC1) and SP became significant only after an exposure to 50 ?M-Cu. On the contrary, for Lm(EC1), SP, and Lm(EC2), MDA content significantly increased even at the lowest concentration. Protein content and catalase (CAT) activity showed a decrease with an increase in Cu concentration. For the species Lm(EC1) and SP, a significant effect of copper on CAT activity was observed only at the highest concentration (100 ?M-Cu) whereas, for Lm(EC2), this effect started to be significant after an exposure to 50 ?M-Cu. Superoxide dismutase (SOD) activity increased with increasing concentrations of Cu, with a very similar trend between the three populations of duckweed. However, due to the facts that enzyme activity is expressed as units of activity per gram of protein and that protein content decreased with Cu exposure, the increase in SOD activity might partly result from a relative increase of this enzyme inside the pool of proteins. Consequently, the results obtained in our experimental conditions strongly suggest that duckweed species from the uranium-polluted area have developed mechanisms to cope with metal toxicity and that this tolerance is based on the existence of protective mechanism to limit the metal uptake rather than on an enhancement of the antioxidative metabolism

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

    International Nuclear Information System (INIS)

    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)

  2. 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...

  3. Duckweed based wastewater stabilization ponds for wastewater treatment (a low cost technology for small urban areas in Zimbabwe)

    Science.gov (United States)

    Dalu, J. M.; Ndamba, J.

    A three-year investigation into the potential use of duckweed based wastewater stabilizations ponds for wastewater treatment was carried out at two small urban areas in Zimbabwe. The study hoped to contribute towards improved environmental management through improving the quality of effluent being discharged into natural waterways. This was to be achieved through the development and facilitation of the use of duckweed based wastewater stabilizations ponds. The study was carried out at Nemanwa and Gutu Growth Points both with a total population of 23 000. The two centers, like more than 70% of Zimbabwe’s small urban areas, relied on algae based ponds for domestic wastewater treatment. The final effluent is used to irrigate gum plantations before finding its way into the nearest streams. Baseline wastewater quality information was collected on a monthly basis for three months after which duckweed ( Lemna minor) was introduced into the maturation ponds to at least 50% pond surface cover. The influent and effluent was then monitored on a monthly basis for chemical, physical and bacteriological parameters as stipulated in the Zimbabwe Water (Waste and Effluent Disposal) regulations of 2000. After five months, the range of parameters tested for was narrowed to include only those that sometimes surpassed the limits. These included: phosphates, nitrates, pH, biological oxygen demand, iron, conductivity, chemical oxygen demand, turbidity, total dissolved solids and total suspended solids. Significant reductions to within permissible limits were obtained for most of the above-mentioned parameters except for phosphates, chemical and biological oxygen demand and turbidity. However, in these cases, more than 60% reductions were observed when the influent and effluent levels were compared. It is our belief that duckweed based waste stabilization ponds can now be used successfully for the treatment of domestic wastewater in small urban areas of Zimbabwe.

  4. EXPRESSION OF ENDOGLUCANASE E1 IN TRANSGENIC DUCKWEED LEMNA MINOR

    Science.gov (United States)

    Transgenic duckweed (Lemna minor) that expresses Acidothermus cellulolyticus E1 endoglucanase was generated using Agrobacterium-mediated transformation. Out of 15 independent transgenic lines, 1 line with the highest CMC-degrading activity was selected for further studies. The 2-week-old transgeni...

  5. Arsenic uptake and speciation in the rootless duckweed Wolffia globosa.

    Science.gov (United States)

    Zhang, Xin; Zhao, Fang-Jie; Huang, Qing; Williams, Paul N; Sun, Guo-Xin; Zhu, Yong-Guan

    2009-01-01

    Duckweeds are a common macrophyte in paddy and aquatic environments. Here, we investigated arsenic (As) accumulation, speciation and tolerance of the rootless duckweed Wolffia globosa and its potential for As phytofiltration. When grown with 1 microm arsenate, W. globosa accumulated two to 10 times more As than four other duckweed or Azolla species tested. W. globosa was able to accumulate > 1000 mg As kg(-1) in frond dry weight (DW), and tolerate up to 400 mg As kg(-1) DW. At the low concentration range, uptake rate was similar for arsenate and arsenite, but at the high concentration range, arsenite was taken up at a faster rate. Arsenite was the predominant As species (c. 90% of the total extractable As) in both arsenate- and arsenite-exposed duckweed. W. globosa was more resistant to external arsenate than arsenite, but showed a similar degree of tolerance internally. W. globosa decreased arsenate in solution rapidly, but also effluxed arsenite. Wolffia globosa is a strong As accumulator and an interesting model plant to study As uptake and metabolism because of the lack of a root-to-frond translocation barrier. PMID:19210724

  6. Efficacy of chlorine concentration and acidic electrolyzed water in decontaminating lettuce leaves artificially inoculated with Escherichia coli O157:H7

    Science.gov (United States)

    Consumption of lettuce has been linked to outbreaks of foodborne illnesses and recalls due to contamination with Escherichia coli O157:H7. Reduction of this risk requires the development of effective and an easily implemented decontamination process. The purpose of this study was to compare the eff...

  7. Microflora of partially processed lettuce.

    OpenAIRE

    Magnuson, J A; King, A. D.; Török, T.

    1990-01-01

    Bacteria, yeasts, and molds isolated from partially processed iceberg lettuce were taxonomically classified. The majority of bacterial isolates were gram-negative rods. Pseudomonas, Erwinia, and Serratia species were commonly found. Yeasts most frequently isolated from lettuce included members of the genera Candida, Cryptococcus, Pichia, Torulaspora, and Trichosporon. Comparatively few molds were isolated; members of the genera Rhizopus, Cladosporium, Phoma, Aspergillus, and Penicillium were ...

  8. Water use and crop coefficient of subsurface drip-irrigated lettuce in Central Arizona Demanda hídrica e coeficiente de cultura da alface irrigada por gotejamento sub-superficial na região central do Arizona

    OpenAIRE

    Aureo S. de Oliveira; Edward C. Martin; Slack, Donald C.; Edward J. Pegelow; Allen D. Folta

    2005-01-01

    A two year field study (1996/97 and 1997/98 growing seasons) was carried out at the Maricopa Agricultural Center (33º04'07" N; 111º57'18" W) of the University of Arizona, USA, to investigate the water use and to derive Kc's for subsurface drip-irrigated head lettuce grown in small weighable lysimeters. Measurement periods ranged from 480 to 1100 ºC-day (96/97) and from 439 to 1098 ºC-day (97/98). These intervals corresponded essentially to the second half of the crop cycle which amounted to a...

  9. Qualidade química da água residual da criação de peixes para cultivo de alface em hidroponia / Chemical quality of residual water from fish breeding tanks for cultivation of hydroponic lettuce

    Scientific Electronic Library Online (English)

    Glauco E. P., Cortez; Jairo A. C. de, Araújo; Paulo A., Bellingieri; Alexandre B., Dalri.

    2009-08-01

    Full Text Available Com o objetivo de avaliar a associação do cultivo de alface em hidroponia com utilização dos resíduos do sistema de criação intensiva de peixe, desenvolveu-se um trabalho no Centro de Aqüicultura, na FCAV-UNESP, Campus de Jaboticabal, SP. A integração foi projetada para que a água circulasse de mane [...] ira fechada entre os sistemas, passando pelos tanques de criação de peixes, por um decantador, para remoção dos resíduos por um reservatório para conversão biológica da amônia em nitrato e pelo sistema hidropônico, retornando aos tanques de criação dos peixes. Foram avaliadas três cultivares de alface, que constituíram os tratamentos com quatro repetições. Os resultados da análise química da água residual da criação indicaram a presença da maioria dos nutrientes minerais necessários ao desenvolvimento vegetal, em concentração próxima aos valores encontrados em soluções nutritivas utilizadas para o cultivo da alface em hidroponia, exceto potássio e magnésio. A baixa concentração de magnésio na água não impediu o desenvolvimento da alface; entretanto, as plantas indicaram sintomas visuais de deficiência deste nutriente. Não houve diferenças entre as cultivares quanto à produtividade e ao peso fresco de plantas. Abstract in english Aiming to evaluate the association of hydroponic lettuce cultivation with residues from a fish intensive breeding system, a project was carried out in the Aquaculture Center in the FCAV-UNESP at Jaboticabal, SP, Brazil. A closed system was designed in order to allow the water to circulate through th [...] e fish tanks, a clarifier tank for removal of residues, a reservoir for biological conversion of ammonia into nitrate, and the hydroponic system. After this process, water returned back to the fish tanks. Three varieties of lettuce, constituting the treatments with four repetitions were evaluated. The results of the chemical analysis of the residual water from the fish tanks indicated the presence of the majority of the mineral nutrients necessary for vegetable development. Their concentration was close to that found in nutrient solutions, used for lettuce hydroponic cultivation, except for potassium and magnesium. The low concentration of magnesium in the water did not prevent lettuce development, although the plants presented visual symptoms of deficiency of this nutrient. Differences were not found between the varieties produced, regarding productivity and the mean weight of fresh plants.

  10. Qualidade química da água residual da criação de peixes para cultivo de alface em hidroponia Chemical quality of residual water from fish breeding tanks for cultivation of hydroponic lettuce

    Directory of Open Access Journals (Sweden)

    Glauco E. P. Cortez

    2009-08-01

    Full Text Available Com o objetivo de avaliar a associação do cultivo de alface em hidroponia com utilização dos resíduos do sistema de criação intensiva de peixe, desenvolveu-se um trabalho no Centro de Aqüicultura, na FCAV-UNESP, Campus de Jaboticabal, SP. A integração foi projetada para que a água circulasse de maneira fechada entre os sistemas, passando pelos tanques de criação de peixes, por um decantador, para remo??ão dos resíduos por um reservatório para conversão biológica da amônia em nitrato e pelo sistema hidropônico, retornando aos tanques de criação dos peixes. Foram avaliadas três cultivares de alface, que constituíram os tratamentos com quatro repetições. Os resultados da análise química da água residual da criação indicaram a presença da maioria dos nutrientes minerais necessários ao desenvolvimento vegetal, em concentração próxima aos valores encontrados em soluções nutritivas utilizadas para o cultivo da alface em hidroponia, exceto potássio e magnésio. A baixa concentração de magnésio na água não impediu o desenvolvimento da alface; entretanto, as plantas indicaram sintomas visuais de deficiência deste nutriente. Não houve diferenças entre as cultivares quanto à produtividade e ao peso fresco de plantas.Aiming to evaluate the association of hydroponic lettuce cultivation with residues from a fish intensive breeding system, a project was carried out in the Aquaculture Center in the FCAV-UNESP at Jaboticabal, SP, Brazil. A closed system was designed in order to allow the water to circulate through the fish tanks, a clarifier tank for removal of residues, a reservoir for biological conversion of ammonia into nitrate, and the hydroponic system. After this process, water returned back to the fish tanks. Three varieties of lettuce, constituting the treatments with four repetitions were evaluated. The results of the chemical analysis of the residual water from the fish tanks indicated the presence of the majority of the mineral nutrients necessary for vegetable development. Their concentration was close to that found in nutrient solutions, used for lettuce hydroponic cultivation, except for potassium and magnesium. The low concentration of magnesium in the water did not prevent lettuce development, although the plants presented visual symptoms of deficiency of this nutrient. Differences were not found between the varieties produced, regarding productivity and the mean weight of fresh plants.

  11. Duckweed in bloom: the 2nd International Conference on Duckweed Research and Applications heralds the return of a plant model for plant biology.

    Science.gov (United States)

    Lam, Eric; Appenroth, Klaus J; Michael, Todd; Mori, Kazuhiro; Fakhoorian, Tamra

    2014-04-01

    More than 50 participants from around the world congregated at Rutgers University for 4 days to discuss the latest advances in duckweed research and applications. Among other developments in the field, exciting new information related to duckweed including genome sequencing, improved genetic transformation, and the identification of a novel plant growth promoting substance from bacteria were reported. PMID:24398764

  12. Dióxido de carbono aplicado via água de irrigação na cultura da alface Carbon dioxide water for lettuce irrigation

    Directory of Open Access Journals (Sweden)

    Raquel A. Furlan

    2001-03-01

    Full Text Available O experimento foi realizado em Piracicaba (SP, com o objetivo de avaliar os efeitos da aplicação de dióxido de carbono via água de irrigação na produtividade e qualidade de alface cultivada em ambiente protegido. Os tratamentos foram constituídos de dois ambientes protegidos, sendo um com aplicação de CO2 e o outro sem aplicação de CO2, onde se cultivou a alface cultivar Verônica. Cada um dos ambientes foi composto por oito parcelas com dimensões de 1,2 m x 6,0 m e espaçadas de 0,80 m. A cultura foi irrigada com o tubo gotejador "Rain Tape" com vazão de 1,15 L/h, pressão de serviço de 60 kPa e espaçamento entre gotejadores de 0,20 m. As irrigações foram feitas diariamente, tendo em vista o objetivo de aplicação diária da dose de CO2 de 50 L/m²/dia. As mudas de alface para o plantio foram formadas em ambiente protegido, em bandejas de isopor, contendo vermiculita como substrato. O transplante foi feito aos 30 dias após o semeio em canteiros de 1,2 m de largura por 6,0 m de comprimento, com espaçamento entre as plantas de 0,30 m e entre linhas de 0,30 m. A aplicação de CO2 foi iniciada no dia 02 de outubro de 1997, sendo feita diariamente, estendendo-se por um período de 30 dias, quando foi então realizada a colheita final da cultura de alface. A aplicação de CO2 via água de irrigação proporcionou aumentos de área foliar e consequentemente do peso da matéria seca da parte aérea, de cerca de 27%, aos 30 dias após o transplantio. O diâmetro da cabeça de alface, número de folhas e o rendimento de cabeças aumentaram em media 15,9%, 5,5% e 28,8%, respectivamente, em comparação aos dados obtidos no tratamento sem aplicação de CO2.The experiment was carried out in Piracicaba, Brazil, in order to evaluate the effects of carbon dioxide, applied with the irrigation water, on the productivity and quality of the lettuce cultivated in plastic greenhouse. The treatments were designed in two plastic greenhouses, one was enriched with CO2 and the other without CO2, where lettuce variety Verônica was cultivated. The plastic greenhouse had eight plots with 1.2 x 6.0 m and spaced by 0.8 m. The crop was irrigated with "Rain Tape" drip with outflow of 1.15 L/h at operating pressure of 60 kPa. The irrigation was scheduled on a daily basis in order to apply 50 liters/m²/day of CO2 daily. The seedlings were produced in plastic greenhouse by using isopor tray with vermiculite as substratum. They were transplanted 30 days after sowing date in beds of 1.2 m width and 6.0 m length, with 0.30 m spaced between plants and 0,30 m between lines. After the application of CO2 (10/02/97 - 11/02/97 plants were harvested. Enrichment of irrigation water with CO2 increased the leaf area, dry weight of the aerial part by 27%, after 30 days of transplanting. The increase in lettuce head diameter, number of leaves and yield of heads was of 15.9%, 5.55% and 28.8%, respectively, in relation to the plot without CO2 application.

  13. Produção e indicadores fisiológicos de alface sob hidroponia com água salina / Production and physiologic indicators of lettuce grown in hydroponics with saline water

    Scientific Electronic Library Online (English)

    Dalva, Paulus; Durval, Dourado Neto; José Antônio, Frizzone; Tales M, Soares.

    2010-03-01

    Full Text Available O uso de água salina na produção de hortaliças constitui no momento atividade essencial, tendo em vista o aumento da demanda de água doce, tanto pela atividade agrícola quanto pelo abastecimento urbano e industrial. O objetivo do trabalho foi avaliar a produção e os indicadores fisiológicos de alfac [...] e cultivada em hidroponia com a utilização de água salina. O experimento foi conduzido em ambiente protegido, em Piracicaba-SP. O delineamento experimental foi de blocos ao acaso, sendo estudados os efeitos de cinco níveis de salinidade da água de irrigação, utilizando-se NaCl [Condutividade elétrica (Cea): 0,42, 1,53, 3,52, 5,55 e 7,43 dS m-1] em duas cultivares de alface (Verônica e Pira Roxa), em esquema fatorial. Foram determinadas massa fresca e seca de folhas, caule, raízes e da parte aérea; teor de nitrato, prolina e clorofila. O aumento da salinidade da água reduziu linearmente as massas fresca e seca das folhas, caule, raízes e da parte aérea. As massas fresca e seca foram 36% e 57% superiores na cultivar Verônica, respectivamente. A cultivar Pira Roxa apresentou maior teor de nitrato 25% (3008 mg L-1), clorofila total 50% (1,46 mg g-1massa fresca) e prolina, 71,43% (0,21 µM g-1massa fresca-1) em relação à Verônica, o que pode ser um mecanismo de adaptação daquela cultivar ao estresse salino. Com relação à produtividade comercial, obteve-se uma perda de 69 e 64% para as cultivares Pira Roxa e Verônica, quando se utilizou água mais salina (7,43 dS m-1). Em relação à produção de massa seca, a perda pelo uso dessa água foi de 53% e 44%, respectivamente. Os resultados obtidos em sistema de cultivo hidropônico podem indicar a possibilidade do uso da água salina como alternativa para produção de hortaliças para produtores que têm disponibilidade de água salina e restrita disponibilidade de água doce, embora com redução na produtividade. Abstract in english The use of saline water in the production of vegetables constitutes at the moment an essential activity, facing the rising demand of fresh water, as for the agricultural activity as for the urban and industrial supplying. This study aimed to evaluate production and physiologic indicators of lettuce [...] in hydroponic system with the use of saline waters. The experiment was carried out in a greenhouse in the period from December 2007 to January 2008, in Piracicaba, Brazil. The experimental design was randomized blocks in factorial scheme - five salinity levels obtained with the addition of NaCl, which resulted in different water electrical conductivity levels (dS m-1): 0,42, 1,53, 3,52, 5,55, 7,43 - and two cultivars of lettuce - Veronica and Pira Roxa. It was determined the fresh and dry mass of leaves, stem, roots and shoot and the content of nitrate, proline and chlorophyll. The increase of water salinity reduced lineally the fresh and dry mass of leaves, stem, roots and shoot. The cv Verônica produced 36% and 57% more shoot fresh and dry mass, respectively, than Pira Roxa. The cv. Pira Roxa accumulated 25% more nitrate (3008 mg L-1), presented 50% more total chlorophyll (1,46 mg g-1fresh mass) and 71,43% more proline (0,21 µM g fresh mass- 1) than the cv Verônica, showing a mechanism of avoiding salinity stress. Cultivars Pira Roxa and Veronica presented loss of 69% and 64% of commercial productivity, respectively, when the most saline water (7,43 dS m-1) was used. In the other hand dry matter was reduced in 53% and 44%, respectively, for cv. Pira Roxa and Verônica in the most saline water. The results obtained in this study can indicate the possibility of using saline water as an alternative for the production of vegetables, specially for growers that have saline water available but restricted fresh water, even with reduction of productivity.

  14. Produção e indicadores fisiológicos de alface sob hidroponia com água salina Production and physiologic indicators of lettuce grown in hydroponics with saline water

    Directory of Open Access Journals (Sweden)

    Dalva Paulus

    2010-03-01

    Full Text Available O uso de água salina na produção de hortaliças constitui no momento atividade essencial, tendo em vista o aumento da demanda de água doce, tanto pela atividade agrícola quanto pelo abastecimento urbano e industrial. O objetivo do trabalho foi avaliar a produção e os indicadores fisiológicos de alface cultivada em hidroponia com a utilização de água salina. O experimento foi conduzido em ambiente protegido, em Piracicaba-SP. O delineamento experimental foi de blocos ao acaso, sendo estudados os efeitos de cinco níveis de salinidade da água de irrigação, utilizando-se NaCl [Condutividade elétrica (Cea: 0,42, 1,53, 3,52, 5,55 e 7,43 dS m-1] em duas cultivares de alface (Verônica e Pira Roxa, em esquema fatorial. Foram determinadas massa fresca e seca de folhas, caule, raízes e da parte aérea; teor de nitrato, prolina e clorofila. O aumento da salinidade da água reduziu linearmente as massas fresca e seca das folhas, caule, raízes e da parte aérea. As massas fresca e seca foram 36% e 57% superiores na cultivar Verônica, respectivamente. A cultivar Pira Roxa apresentou maior teor de nitrato 25% (3008 mg L-1, clorofila total 50% (1,46 mg g-1massa fresca e prolina, 71,43% (0,21 µM g-1massa fresca-1 em relação à Verônica, o que pode ser um mecanismo de adaptação daquela cultivar ao estresse salino. Com relação à produtividade comercial, obteve-se uma perda de 69 e 64% para as cultivares Pira Roxa e Verônica, quando se utilizou água mais salina (7,43 dS m-1. Em relação à produção de massa seca, a perda pelo uso dessa água foi de 53% e 44%, respectivamente. Os resultados obtidos em sistema de cultivo hidropônico podem indicar a possibilidade do uso da água salina como alternativa para produção de hortaliças para produtores que têm disponibilidade de água salina e restrita disponibilidade de água doce, embora com redução na produtividade.The use of saline water in the production of vegetables constitutes at the moment an essential activity, facing the rising demand of fresh water, as for the agricultural activity as for the urban and industrial supplying. This study aimed to evaluate production and physiologic indicators of lettuce in hydroponic system with the use of saline waters. The experiment was carried out in a greenhouse in the period from December 2007 to January 2008, in Piracicaba, Brazil. The experimental design was randomized blocks in factorial scheme - five salinity levels obtained with the addition of NaCl, which resulted in different water electrical conductivity levels (dS m-1: 0,42, 1,53, 3,52, 5,55, 7,43 - and two cultivars of lettuce - Veronica and Pira Roxa. It was determined the fresh and dry mass of leaves, stem, roots and shoot and the content of nitrate, proline and chlorophyll. The increase of water salinity reduced lineally the fresh and dry mass of leaves, stem, roots and shoot. The cv Verônica produced 36% and 57% more shoot fresh and dry mass, respectively, than Pira Roxa. The cv. Pira Roxa accumulated 25% more nitrate (3008 mg L-1, presented 50% more total chlorophyll (1,46 mg g-1fresh mass and 71,43% more proline (0,21 µM g fresh mass- 1 than the cv Verônica, showing a mechanism of avoiding salinity stress. Cultivars Pira Roxa and Veronica presented loss of 69% and 64% of commercial productivity, respectively, when the most saline water (7,43 dS m-1 was used. In the other hand dry matter was reduced in 53% and 44%, respectively, for cv. Pira Roxa and Verônica in the most saline water. The results obtained in this study can indicate the possibility of using saline water as an alternative for the production of vegetables, specially for growers that have saline water available but restricted fresh water, even with reduction of productivity.

  15. Duckweed Lemna minor (Liliopsida, Lemnaceae as a natural biofilter in brackish and fresh closed recirculating systems

    Directory of Open Access Journals (Sweden)

    Tharwat S. Nashashibi

    2012-12-01

    Full Text Available This study attempted to assess the potential use of common duckweed Lemna minor asnatural biofilter in brackish closed recirculating systems of 4 g/L salinity and to evaluate the effect ofsalinities in the ranges of 1-7 g L-1 on the duckweed’s ammonium NH4 +1uptake. Furthermore thepossibility of nitrification as a second mechanism of nitrogen removal in closed recirculating systems wasinvestigated. Three closed recirculating systems each having 20 mixed Oreochromis niloticus were used.Duckweed L. minor and fresh water were added in system 1, fresh water only in system 2, and duckweedwith brackish water in system 3. Ammonium NH4 +1and nitrate NO3-1 were tested periodically in eachsystem during a 1.5 month period. Another three experiments were run in parallel using aquariumsincubated with 60.00 g fresh weight L. minor at salinities in the ranges of 1-7 g L-1 for two weeks.Aquariums were exposed directly to sunlight in experiment 1 and 3, and were placed in the dark inexperiment 2. The nitrogen source in experiment 1 and 2 was 100 mg L-1 of NH4Cl, and 280 mg L-1 ofNH4Cl in experiment 3. NH4 +1and NO3-1 levels were monitored as above. L. minor managed to reduce theaverage NH4 +1levels to 0.5 mg L-1, 0.43 mg L-1below the standard recommended levels in both brackishand fresh water systems, respectively. Ammonium NH4 +1 uptake was coupled with nitrate NO3-1 uptakeunder favorable conditions of sunlight. Salinity in the ranges from 1-7 g L-1 enhanced ammonium NH4 +1uptake (r = 0.8819, p = 0.023 without affecting nitrate NO3-1 uptake or any observed mortality of theduckweed. Nitrification was a second mechanism of nitrogen removal in a closed recirculating system,but it was affected by salinity and light. Average ammonium NH4 +1of 51.8 mg L-1 was toxic to L. minorand death was observed within a week in experiment 3. The duckweed L. minor was an efficient naturalbiofilter in both brackish and fresh water closed recirculating systems.

  16. NEW BIOLOGICAL DIETARY FEED SUPPLEMENT FOR LAYING HENS WITH MICROELEMENTS BASED ON DUCKWEED (LEMNA MINOR)

    OpenAIRE

    Zuzanna Witkowska; Agnieszka Saeid; Katarzyna Chojnacka; Zbigniew Dobrzanski; Henryk Gorecki; Izabela Michalak; Mariusz Korczynski; Sebastian Opalinski

    2012-01-01

    In this study the applicability of enriched duckweed (Lemna minor) as a dietary supplement witch microelements is reported. In our previous studies, the technology of new feed additives with microelements based on duckweed biomass was elaborated. Here, we report the evaluation of the properties of a new product. The effect of duckweed enriched with microelements on the productivity parameters of laying hens was studied in zootechnical research. Birds feed was supplemented with duckweed enrich...

  17. Duckweed Lemna minor (Liliopsida, Lemnaceae) as a natural biofilter in brackish and fresh closed recirculating systems

    OpenAIRE

    Tharwat S. Nashashibi; Mutaz A. Al-Qutob

    2012-01-01

    This study attempted to assess the potential use of common duckweed Lemna minor asnatural biofilter in brackish closed recirculating systems of 4 g/L salinity and to evaluate the effect ofsalinities in the ranges of 1-7 g L-1 on the duckweed’s ammonium NH4 +1uptake. Furthermore thepossibility of nitrification as a second mechanism of nitrogen removal in closed recirculating systems wasinvestigated. Three closed recirculating systems each having 20 mixed Oreochromis niloticus were used.Duckwee...

  18. Effects of allelochemical extracted from water lettuce (Pistia stratiotes Linn.) on the growth, microcystin production and release of Microcystis aeruginosa.

    Science.gov (United States)

    Wu, Xiang; Wu, Hao; Chen, Junren; Ye, Jinyun

    2013-11-01

    This study explored the optimisation of a method of extracting allelochemicals from Pistia stratiotes Linn., identified the optimal dose range for the allelochemicals' anti-algal effect and investigated their impact on the growth of Microcystis aeruginosa, as well as the production and release of microcystin-LR (MC-LR). Based on measured changes in algal cell density and chlorophyll a (Chl-a) content, the allelochemicals were confirmed to have the strongest anti-algal effect with the lowest half-effect concentration of 65 mg L(-1) when they were extracted using ethyl acetate as the extraction solvent, 1:20 g mL(-1) as the extraction ratio and 1 h as the extraction time. The allelochemicals extracted from P. stratiotes using this optimal method exhibited the strongest inhibitory effect on the growth of algae when used within a dose range of 60-100 mg L(-1); the relative inhibitory ratio reached 50-90%, and Chl-a content reduced 50-75% in algae cell cultures within 3-7 days. In addition, the extracted allelochemical compounds demonstrated no significant impact on the extracellular release of MC-LR during the culturing period. The amount of intracellular MC-LR per 10(6) algal cells increased depending on the increasing dose of allelochemicals from P. stratiotes after 7 days of culturing and maintained stability after 16 days. There was no increase in the total amount of MC-LR in the algal cell culture medium. Therefore, the application of allelochemicals from P. stratiotes to inhibit M. aeruginosa has a high degree of ecological safety and can be adopted in practical applications for treating water subjected to algae blooms because the treatment can effectively inhibit the proliferation of algal cells without increasing the release of cyanotoxin. PMID:23653319

  19. Properties of soil and hydroponicaly grown lettuce

    OpenAIRE

    Mlakar, Mirjam

    2014-01-01

    The aim of the thesis was to examine the quality of the lettuce Lactuca sativa L., which was grown with two methods. Hydroponically grown lettuce was compared with lettuce grown in soil. The purpose of this research was to find out with which method the lettuce would look better and with which method the quality of the lettuce`s nutritiousness would be higher. We ascertained that plants grown with hydroponics did look better and were heavier. About quality results showed that the contents of ...

  20. 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

    2014-01-01

    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. PMID:24220663

  1. Growth and photosynthesis of lettuce

    OpenAIRE

    Holsteijn, H.M.C., van

    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 this study on lettuce emphasis has been given to light interception in the poor light period, the relationship of growth rate and relative growth rate with time, dry weight and soil cover, and to photosynthesis properties of the ...

  2. Survey of duckweed diversity in Lake Chao and total fatty acid, triacylglycerol, profiles of representative strains.

    Science.gov (United States)

    Tang, J; Li, Y; Ma, J; Cheng, J J

    2015-09-01

    Lemnaceae (duckweeds) are widely distributed aquatic flowering plants. Their high growth rate, starch content and suitability for bioremediation make them potential feedstock for biofuels. However, few natural duckweed resources have been investigated in China, and there is no information about total fatty acid (TFA) and triacylglycerol (TAG) composition of duckweeds from China. Here, the genetic diversity of a natural duckweed population collected from Lake Chao, China, was investigated using multilocus sequence typing (MLST). The 54 strains were categorised into four species in four genera, representing 12 distinct sequence types. Strains representing Lemna aequinoctialis and Spirodela polyrhiza were predominant. Interestingly, a surprisingly high degree of genetic diversification within L. aequinoctialis was observed. The four duckweed species revealed a uniform fatty acid composition, with three fatty acids, palmitic acid, linoleic acid and linolenic acid, accounting for more than 80% of the TFA. The TFA in biomass varied among species, ranging from 1.05% (of dry weight, DW) for L. punctata and S. polyrhiza to 1.62% for Wolffia globosa. The four duckweed species contained similar TAG contents, 0.02% mg · DW(-1). The fatty acid profiles of TAG were different from those of TFA, and also varied among the four species. The survey investigated the genetic diversity of duckweeds from Lake Chao, and provides an initial insight into TFA and TAG of four duckweed species, indicating that intraspecific and interspecific variations exist in the content and composition of both TFA and TAG in comparison with other studies. PMID:25950142

  3. Biology and Genetics of Lettuce Dieback Disease and Lettuce Necrotic Stunt Virus.

    Science.gov (United States)

    Lettuce dieback, a new soil-borne disease of lettuce, emerged in the 1990s to cause severe losses for lettuce production in the western United States. The disease is caused by Tomato bushy stunt virus (TBSV) and the recently described tombusvirus, Lettuce necrotic stunt virus (LNSV). The complete ge...

  4. Chemical characterisation and analysis of the cell wall polysaccharides of duckweed (Lemna minor).

    Science.gov (United States)

    Zhao, X; Moates, G K; Wellner, N; Collins, S R A; Coleman, M J; Waldron, K W

    2014-10-13

    Duckweed is potentially an ideal biofuel feedstock due to its high proportion of cellulose and starch and low lignin content. However, there is little detailed information on the composition and structure of duckweed cell walls relevant to optimising the conversion of duckweed biomass to ethanol and other biorefinery products. This study reports that, for the variety and batch evaluated, carbohydrates constitute 51.2% (w/w) of dry matter while starch accounts for 19.9%. This study, for the first time, analyses duckweed cell wall composition through a detailed sequential extraction. The cell wall is rich in cellulose and also contains 20.3% pectin comprising galacturonan, xylogalacturonan, rhamnogalacturonan; 3.5% hemicellulose comprising xyloglucan and xylan, and 0.03% phenolics. In addition, essential fatty acids (0.6%, ?-linolenic and linoleic/linoelaidic acid) and p-coumaric acid (0.015%) respectively are the most abundant fatty acids and phenolics in whole duckweed. PMID:25037369

  5. Evaluación de tratamientos para disminuir cadmio en lechuga (Lactuca sativa L.) regada con agua del río Bogotá / Evaluation of treatments to reduce cadmium concentration in lettuce (Lactuca sativa L.) irrigated with water from the Bogota River

    Scientific Electronic Library Online (English)

    JULIANA, RUIZ.

    2011-12-01

    Full Text Available Las aguas del río Bogotá presentan altos niveles de contaminación, incluyendo metales pesados, y sus aguas son utilizadas para el riego de importantes extensiones agrícolas. El presente estudio se realizó en el Centro Agropecuario Marengo (Mosquera, Cundinamarca) y su objetivo fue evaluar tratamient [...] os sencillos para disminuir la acumulación de cadmio en lechuga. Los tratamientos fueron: (1) crecimiento selectivo de arvenses en las parcelas; (2) aplicación de CaCO3 antes de trasplante; (3) incorporación de compost antes de trasplante, y (4) control. Se aplicó un diseño de bloques completos al azar con tres repeticiones. Se realizaron mediciones de cadmio en agua, suelo y lechuga. Se tomaron medidas de crecimiento de la lechuga, y se midió el pH y la conductividad eléctrica del suelo. Se encontraron altas concentraciones iniciales de cadmio en suelo (3,97 mg kg-1). Estas concentraciones bajaron significativamente a los 46 días después del trasplante en el tratamiento con arvenses (3,38 mg kg-1). El tratamiento con compost disminuyó significativamente la concentración de cadmio en lechuga (0,26 mg kg-1) respecto a los otros tratamientos (0,45–0,60 mg kg-1) y en corto tiempo aumentó significativamente el peso fresco de las lechugas respecto a los demás tratamientos sin fertilizar; no se encontró relación de esta disminución con el aumento del pH. Abstract in english The water of the Bogota River has high levels of contamination including heavy metals and its waters are used to irrigate crops in important areas. The present study was conducted in the Marengo Agricultural Center (Mosquera, Cundinamarca) and its objective was to evaluate easy treatments to reduce [...] cadmium accumulation in lettuce. The treatments used were: (1) Selective weed growth in the plots, (2) CaCO3 application before plant transplanting, (3) Compost application before plant transplanting and (4) the Control. This study was performed with a randomized complete block design with three repetitions. Amounts of cadmium in the water, soil and lettuce were measured. Measurements of plant growth, pH and electrical conductivity of the soil were also taken. The results showed high initial concentrations of cadmium in the soil (3.97 mg kg-1). These concentrations were found to be significantly lower 46 days after transplanting in the weed treatment (3.38 mg kg-1). The compost treatment significantly lowered the concentration of cadmium in lettuce compared to the other treatments and quickly, significantly increased fresh weight compared to the other treatments without fertilizer; no relationship between the decrease of cadmium and increased pH was found.

  6. Agronomic efficiency of intercropping tomato and lettuce

    OpenAIRE

    Arthur B Cecílio Filho; Bráulio L.A. Rezende; José C Barbosa; Leilson C Grangeiro

    2011-01-01

    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 ...

  7. Gaseous nitrogen losses during glasshouse cultivation of lettuce on a sandbed

    OpenAIRE

    Postma, R.; Oenema, O.; Bussink, D.W.; Heinen, M.; Moolenbroek, J., van

    1994-01-01

    Ammonia volatilization, denitrification and nitrous oxide emission from lettuce grown on a sandbed were measured. Nutrients and water were supplied by recirculated drip irrigation. Ammonia volatilization, and nitrous oxide emission, determined with f

  8. 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...

  9. 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.

  10. Suitability of duckweed (Lemna minor) as feed for fish in polyculture system

    OpenAIRE

    M.Z.H. Talukdar

    2012-01-01

    In the present study, we conducted an experiment to evaluate the effects of duckweed (Lemna minor) as feed on fish production in polyculture. The experiment had 2 treatments where in treatment 1 (T1) ponds were supplied with duckweed as feed and in treatment 2 (T2) ponds were kept as control (without supply of duckweed). Average survival rates in T1 and T2 were 90 and 89%, respectively. The specific growth rates (SGR) were higher in T1. Calculated net production in T1 was 6.25 tons ha.-1 yr.-...

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

    International Nuclear Information System (INIS)

    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

  12. 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...

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

    Science.gov (United States)

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

    2015-07-01

    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. PMID:26193291

  14. 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.; Abaidoo, R.C.

    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 c...... health risks from using polluted water in vegetable farming.......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...

  15. Oxidation of Secondary Alcohols by Duckweed: A Biotransformation Experiment for Undergraduate Students.

    Science.gov (United States)

    Karfarski, Pawel; And Others

    1988-01-01

    Describes an experiment designed to use the ability of duckweed to convert the secondary hydroxyl moieties into ketone groups. Discusses the preparation of plant material, materials, procedures, and results for this biotransformation experiment for undergraduate students. (CW)

  16. The logistic growth of duckweed (Lemna minor) and kinetics of ammonium uptake.

    Science.gov (United States)

    Zhang, Kun; Chen, You-Peng; Zhang, Ting-Ting; Zhao, Yun; Shen, Yu; Huang, Lei; Gao, Xu; Guo, Jin-Song

    2014-01-01

    Mathematical models have been developed to describe nitrogen uptake and duckweed growth experimentally to study the kinetics of ammonium uptake under various concentrations. The kinetics of duckweed ammonium uptake was investigated using the modified depletion method after plants were grown for two weeks at different ammonium concentrations (0.5-14 mg/L) in the culture medium. The maximum uptake rate and Michaelis-Menten constant for ammonium were estimated as 0.082 mg/(g fresh weight x h) and 1.877 mg/L, respectively. Duckweed growth was assessed when supplied at different total nitrogen (TN) concentrations (1-5 mg/L) in the culture medium. The results showed that the intrinsic growth rate was from 0.22 to 0.26 d(-1), and TN concentrations had no significant influence on the duckweed growth rate. PMID:24645435

  17. Toxicity and genotoxicity of water and sediment from streams on dotted duckweed (Landoltia punctata) / Toxicidade e genotoxicidade da água e sedimentos dos córregos em lentilha d'água (Landoltia punctata)

    Scientific Electronic Library Online (English)

    R, Factori; SM, Leles; GC, Novakowski; CLSC, Rocha; SM, Thomaz.

    2014-11-01

    Full Text Available Muitos rios são utilizados como fonte de abastecimento de cidades inteiras e a qualidade de suas águas está relacionada diretamente à qualidade de seus afluentes. Infelizmente córregos têm sua importância negligenciada pelo homem sendo alvo [...] de despejos domésticos e industriais e também do carreamento de nutrientes e pesticidas das áreas rurais. Diante da complexidade das misturas que atingem estes corpos d'água, o presente estudo teve por objetivo avaliar a qualidade da água e do sedimento de dez afluentes do rio Pirapó no município de Maringá, Estado do Paraná. Utilizou-se a macrófita aquática flutuante Landoltia punctata (G. Meyer) Les & D.J.Crawford como organismo teste em microcosmos, sendo que a toxicidade das amostras de água e sedimento foi avaliada pela taxa de crescimento relativo, pelo índice de biomassa seca por fresca, e pelos efeitos genotóxicos (ensaio de cometa). Amostras de água e sedimento de cada córrego foram dispostos em microcosmos com L. punctata. Após 7 dias as plantas foram coletadas para as análises. Os níveis de nutrientes foram maiores que o do local de referência indicando eutrofização; porém, os resultados indicaram efeito tóxico em apenas três dos córregos e genotóxico em todos os córregos. Abstract in english Most rivers are used as a source to supply entire cities; the quality of water is directly related to the quality of tributaries. Unfortunately men have neglected the importance of streams, which receive domestic and industrial effluents an [...] d transport nutrients and pesticides from rural areas. Given the complexity of the mixtures discharged into these water bodies, this study aimed to evaluate the quality of water and sediment of ten tributaries of Pirapó River, in Maringá, Paraná State, Brazil. To this end, the free-floating macrophyte Landoltia punctata (G. Meyer) Les & D.J.Crawford was used as test organism in microcosm, and the toxicity of water and sediment samples was evaluated by the relative growth rate, dry/fresh biomass ratio, and genotoxic effects (comet assay). Samples of water and sediment of each stream were arranged in microcosms with L. punctata. Seven days later, plants were collected for analysis. Nutrient levels were higher than the reference location, indicating eutrophication, but the results indicated a toxic effect for only three streams, and a genotoxic effect for all streams.

  18. Nitrogen Transformations and Removal Mechanisms in Algal and Duckweed Waste Stabilisation Ponds:

    OpenAIRE

    Zimmo, O.

    2003-01-01

    Effective treatment of nitrogen containing wastewater is required to prevent eutrophication and groundwater pollution. This thesis shows that effective treatment may be combined with substantial nitrogen recovery in duckweed-based waste stabilisation ponds. In these ponds nitrogen is absorbed by rapidly growing duckweed and in this way turned into valuable animal feed. A pilot study was conducted at Birzeit University in Palestine to investigate nitrogen transformation and removal mechanisms ...

  19. Improving Production of Bioethanol from Duckweed (Landoltia punctata) by Pectinase Pretreatment

    OpenAIRE

    Qian Chen; Yanling Jin; Guohua Zhang; Yang Fang; Yao Xiao; Hai Zhao

    2012-01-01

    Landoltia punctata, a widely distributed duckweed strain with the ability to accumulate starch, was used as a novel feedstock for bioethanol production by Saccharomyces cerevisiae. To improve ethanol production, pectinase pretreatment was used to release much more glucose from L. punctata mash and the pretreatment conditions (enzyme loading, temperature and pretreatment time) for the duckweed were optimized by using a surface resp...

  20. Antioxidant and Antimicrobial Activities of an Aquatic Plant: Duckweed (Lemna minor L.)

    OpenAIRE

    GÜLÇ?N, ?lhami; ,; K?REÇC?, Ekrem; AKKEM?K, Ebru; TOPAL, Fevzi; H?SAR, Olcay

    2010-01-01

    Duckweed (Lemna minor L. Lemnaceae) is a widespread, free-floating aquatic macrophyte, a source of food for waterfowl and a shelter for small aquatic invertebrates. It grows quickly and reproduces faster than other vascular plants. The objective of this study was to determine the antioxidant, antiradical, antimicrobial, and anticandidal activities of duckweed using different in vitro methodologies. For evaluation of antioxidant and antiradical activities, 2,2´-azino-bis(3-ethylbenzthiazoline-...

  1. Nitrogen transformations and removal mechanisms in algal and duckweed stabilisation ponds

    OpenAIRE

    Zimmo, O.

    2003-01-01

    This thesis describes the results of a comparative study of the performance of algae-based ponds (ABPs) and duckweed-based ponds (DBPs) for wastewater treatment, with emphasis on nitrogen transformations and removal mechanisms.Batch experiments simulating algae and duckweed ( Lemna gibba ) stabilisation ponds for domestic wastewater treatment were conducted to quantify the importance of various nitrogen removal mechanisms under controlled conditions of pH and DO. N-removal in both systems by ...

  2. Improving Production of Bioethanol from Duckweed (Landoltia punctata) by Pectinase Pretreatment

    OpenAIRE

    Chen, Qian; Jin, Yanling; Zhang, Guohua; Fang, Yang; Xiao, Yao; Zhao, Hai

    2012-01-01

    Landoltia punctata, a widely distributed duckweed strain with the ability to accumulate starch, was used as a novel feedstock for bioethanol production by Saccharomyces cerevisiae. To improve ethanol production, pectinase pretreatment was used to release much more glucose from L. punctata mash and the pretreatment conditions (enzyme loading, temperature and pretreatment time) for the duckweed were optimized by using a surface response design. The results showed that maximum glucose yield was ...

  3. 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.; Abaidoo, R.C.

    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...... lower crop densities and restricted other routine farm activities. Watering cans were the most popular method. Using watering cans with caps on outlets from a height <0.5 m reduced thermotolerant coliforms by 2.5 log units and helminthes by 2.3 eggs per 100 g of lettuce compared with using watering cans...

  4. Feeding Diets Containing Different Forms of Duckweed on Productive Performance and Egg Quality of Ducks

    Directory of Open Access Journals (Sweden)

    B. Indarsih

    2012-08-01

    Full Text Available The present experiment was undertaken to study the feeding effect of diets containing different forms of duckweed for local ducks on their productive performance and egg quality or egg yolk pigmentation. A total of 90 birds of 24 wk old ducks were randomly divided into 18 experimental units of 2.0 x 1.0 m2 of cages. The experiment was assigned in a completely randomized design (3 treatments with 6 replicates, 5 birds each. There were 3 dietary treatments, namely P1= ducks fed a complete diet containing 20 % of dried duckweed and given in the form of dry-mash; P2= a complete diet in P1 but it was offered in wet form (slurry; and P3= ducks were offered basal diet in the form of dry-mash and fresh duckweed was offered separately ad libitum. Diets were formulated to have similar nutritional contents. Feed consumption, feed conversion ratio (FCR, and egg yolk pigmentation were measured. The result of the study showed that these three parameters were affected by the feeding different forms of duckweed. Feeding diet with fresh duckweed brought about the best pigmentation than did the dry one. Fresh duckweed offers a promise as a potential feedstuff for ducks and has a good implication in reducing feed processing cost.

  5. The microbiological safety of duckweed fed chickens: a risk assessment of using duckweed reared on domestic wastewater as a protein source in broiler chickens

    Science.gov (United States)

    Moyo, S.; Dalu, J. M.; Ndamba, J.

    The possibility of transmission of pathogens from duckweed supplemented feed to chickens and consequently to the human consumer necessitated the microbiological testing of duckweed fed chickens. This assessment was thus done to determine whether there is transmission of pathogens from the duckweed supplemented feed to the chickens; determine whether such infection would be systemic or be confined to the gastro-intestinal tract of the birds; and to investigate the microbial load and distribution of the microbes with age. The study birds were sacrificed at 3, 6, 8 and 10 weeks of age and examined for the indicator organisms Escherichia coli and Salmonella spp. There was no discernible pattern in the microbial load of both the duckweed fed chickens and control birds with age although the control birds sampled clearly had a lower microbial load than the experimental flock. Some Salmonella and two enteropathogenic E. coli strains were isolated from control and experimental sub-samples at 3 weeks. There were no Salmonellae isolated in the subsequent batches of birds and feed although a number of E. coli were isolated. More isolates were obtained from the three weeks’ sub-samples (collected during wet weather) than from all the other sub-samples. The use of duckweed at this inclusion rate under the processing conditions at Nemanwa was thus concluded to be microbiologically safe as long as due caution is exercised during the processing of the duckweed and handling of the birds. There are indications that the chickens may get contaminated especially during wet weather as evidenced by the isolation of E. coli and Salmonella spp from the first batch sub-samples. This was attributed to poor environmental sanitation at the plant particularly in view of the prevailing wet conditions at the time.

  6. Agronomic efficiency of intercropping tomato and lettuce.

    Science.gov (United States)

    Cecílio Filho, Arthur B; Rezende, Bráulio L A; Barbosa, José C; Grangeiro, Leilson C

    2011-09-01

    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. PMID:21861045

  7. Effect of water availability on physiological performance and lettuce crop yield (Lactuca sativa) / Efecto de la disponibilidad hídrica sobre el desempeño fisiológico y productivo de un cultivo de lechuga (Lactuca sativa)

    Scientific Electronic Library Online (English)

    Marco A, Molina-Montenegro; Andrés, Zurita-Silva; Rómulo, Oses.

    2011-04-01

    Full Text Available El agua es un elemento esencial para las plantas, afectando la mayoría de los procesos fisiológicos implicados en el crecimiento y productividad. La sequía es uno de los factores de estrés más común que puede limitar la productividad agrícola a nivel mundial. Muchos cultivos poseen altas demandas hí [...] dricas, no obstante en muchos países y producto del cambio climático global, el agua disponible para riego se torna limitante. De hecho, los actuales modelos de cambio climático global señalan a Chile como una de las zonas donde la disminución en las precipitaciones sería más evidente. En el presente trabajo, se evaluó la variación en el intercambio gaseoso y producción de biomasa fresca en cultivos de lechugas sometidos a diferentes niveles de disponibilidad hídrica. Adicionalmente, se evaluó la concentración de azúcares solubles totales y la eficiencia en el uso del agua (EUA) como mecanismos implicados en la tolerancia al déficit hídrico. En general, aquellos individuos sometidos a menor disponibilidad hídrica presentaron menores valores de intercambio gaseoso y biomasa fresca, en comparación a sus con-específicos crecidos con el 75 y 100% de la disponibilidad hídrica. Por otro lado, aquellos individuos con la disponibilidad hídrica intermedia presentaron mayores contenidos de azúcares solubles totales y una mayor EUA. Los resultados de la presente investigación sugieren, que aquellos cultivos sometidos a eventos prolongados o intensos de sequía podrían verse afectados en su fisiología y productividad. No obstante, leves disminuciones en la disponibilidad hídrica permitirían a los cultivos de lechugas mantener una elevada EUA, manteniendo una elevada tasa fotosintética y una alta productividad. Abstract in english Water is essential for plants, affecting the majority of the physiological processes related to growth and productivity. Water shortage is one of the most common factors that limit crop productivity worldwide. Many cultivars have elevated water requirements, nevertheless in some countries due to glo [...] bal climate change effects, the availability of water for irrigation is becoming limited. In fact, current models of climate changes predict that central Chile will be a sensitive zone where precipitation will drastically decrease. In this study, the variation of gas exchange and production of fresh biomass in a lettuce cultivar, grown under different water availability regimes, was evaluated. Additionally, the concentration of total soluble sugar and water use efficiency (WUE) as mechanisms related to water shortage responses were also evaluated. Overall, individuals with the lowest water availability (50%) showed lower gas exchange and fresh biomass values than their conspecifics grown in optimal irrigated conditions. On the other hand, those individuals with moderate water shortage showed the highest concentration of total soluble sugars and WUE. Our results suggested that cultures exposed to extensive or intense drought events, could be negatively affected in both physiological performance and productivity. Nevertheless, slight decreases in water availability can enable lettuce plants to exhibit a high WUE, maintaining high levels of physiological performance and productivity.

  8. Response of hydroponically grown head lettuce on residual monomer from polyacrylamide.

    Science.gov (United States)

    Mroczek, E; Konieczny, P; Kleiber, T; Wa?kiewicz, A

    2014-01-01

    The aim was to assess acrylamide monomer (AMD) uptake by hydroponically grown lettuce. Lettuce was cultivated by applying plant tissue testing in a recycled system by the use of nutrient solutions prepared with two water-soluble flocculants F3 and F4 containing 176 and 763 mg kg(-1) of AMD, respectively. The effects on growth, fresh weight and plant leaf quality were evaluated by comparing these treatments and one control standard nutrient solution typically recommended for lettuce hydroponic cultivation. To assess the nutritional status of lettuce, samples were collected and lyophilised before determination of the selected micro- and macro-element contents. An HPLC with photodiode array detector method was applied to determine AMD in both selected flocculants and dried plant samples. Results show that lettuces cultivated under the conditions described above absorb AMD from nutrient solutions into their leaves. The AMD presence in recycled nutrient solutions has a negative influence on the growth of lettuce, reducing their average fresh weight and average number of leaves. The study confirmed that the problem of AMD mobility and its accumulation risk in plants should to be an important topic with respect to safe polyacrylamide (PAM) handling in the agro food area. PMID:24916210

  9. Análise sensorial, teores de nitrato e de nutrientes de alface cultivada em hidroponia sob águas salinas / Sensory analysis, nitrate and nutrient concentration of lettuce grown in hydroponics under saline water

    Scientific Electronic Library Online (English)

    Dalva, Paulus; Durval, Dourado Neto; Eloi, Paulus.

    2012-03-01

    Full Text Available O presente trabalho teve como objetivos determinar os teores de nutrientes e de nitrato e realizar análise sensorial de alface cultivada em sistema hidropônico sob água salina. O experimento foi conduzido em ambiente protegido no período de dezembro de 2007 a janeiro de 2008, em Piracicaba (SP). O d [...] elineamento experimental foi de blocos ao acaso, sendo estudados cinco níveis de salinidade da água de irrigação, utilizando-se NaCl (Condutividade elétrica da água (CEa): 0,42, 1,53, 3,52, 5,55 e 7,43 dS m-1) em duas cultivares de alface (Verônica e Pira Roxa), em esquema fatorial. Foram avaliados a análise sensorial aplicando escala hedônica e através dessa, o que os provadores mais apreciaram e o que menos gostaram de cada amostra, intenção de compra e consumo, teor de nitrato, absorção de nutrientes pela folhas e determinação dos nutrientes presentes na solução nutritiva. Para o atributo sabor a cultivar Verônica recebeu as melhores notas no nível de salinidade 1,53 e 5,55 dS m-1. Para a cultivar Pira Roxa a melhor nota foi atribuída para a alface produzida na água não salina. Para os demais atributos não houve diferença significativa nos diferentes níveis de salinidade. Com relação à intenção de compra, constatou-se que as alfaces cv. Verônica e Pira Roxa apresentaram boa aceitação de mercado. Os menores níveis de nitrato (1960 mg kg-1 e 2620 mg kg-1 de massa de matéria fresca), da Verônica e Pira Roxa, respectivamente, foram relacionados à condutividade elétrica de 0,42 dS m-1, aumentando a salinidade da água para 7,43 dS m-1, o teor foliar de nitrato aumentou para 2500 mg kg-1 e 3420 mg kg-1 para as cultivares Verônica e Pira Roxa. Como o tempo de exposição da alface à salinidade em sistema hidropônico foi curto, em torno de 25 dias, não se verificou sintomas de deficiência nutricional e toda alface foi classificada como apropriada para consumo humano. Abstract in english This study aimed to evaluate the content of nutrients and nitrate and perform sensory analysis of lettuce in hydroponic system under saline water. The experiment was carried out in a greenhouse from December, 2007 to January, 2008, in Piracicaba. The experimental design was randomized blocks and fac [...] torial scheme (five salinity levels obtained with the addition of NaCl that resulted in different electrical conductivities of the water (dS m-1): 0.42, 1.53, 3.52, 5.55, 7.43 and two cultivas of lettuce (Veronica and Pira Roxa). The evaluations were: sensory analysis applying hedonic scale and through this, which sample presented the best and the least taste, the purchase intent and consumption, nitrate, absorption of nutrients by leaves and determination of nutrients in the nutrient solution. For the attribute of cultivars, Veronica received the highest marks in salt level 1.53 and 5.55 dS m-1. For cultivar Pira Roxa was awarded the best grade for lettuce grown in non-saline water. For other attributes there was no significant difference in levels of salinity. To purchase intention, it was found that cv. Verônica and Pira Roxa had good market acceptance. The lowest levels of nitrate (1960 mg kg-1 and 2620 mg kg-1 fresh weight) of Verônica and Pira Roxa, respectively, were related to the electrical conductivity of 0.42 dS m-1, increasing water salinity to 7.43 dS m-1, the leaf content of nitrate increased to 2500 mg kg-1 and 3420 mg kg-1 for the cultivars Verônica and Pira Roxa. As the time of exposure to salt in a hydroponic system was short, around 25 days, there were no symptoms of nutrient deficiency and whole lettuce was classified as suitable for human consumption.

  10. Análise sensorial, teores de nitrato e de nutrientes de alface cultivada em hidroponia sob águas salinas Sensory analysis, nitrate and nutrient concentration of lettuce grown in hydroponics under saline water

    Directory of Open Access Journals (Sweden)

    Dalva Paulus

    2012-03-01

    Full Text Available O presente trabalho teve como objetivos determinar os teores de nutrientes e de nitrato e realizar análise sensorial de alface cultivada em sistema hidropônico sob água salina. O experimento foi conduzido em ambiente protegido no período de dezembro de 2007 a janeiro de 2008, em Piracicaba (SP. O delineamento experimental foi de blocos ao acaso, sendo estudados cinco níveis de salinidade da água de irrigação, utilizando-se NaCl (Condutividade elétrica da água (CEa: 0,42, 1,53, 3,52, 5,55 e 7,43 dS m-1 em duas cultivares de alface (Verônica e Pira Roxa, em esquema fatorial. Foram avaliados a análise sensorial aplicando escala hedônica e através dessa, o que os provadores mais apreciaram e o que menos gostaram de cada amostra, intenção de compra e consumo, teor de nitrato, absorção de nutrientes pela folhas e determinação dos nutrientes presentes na solução nutritiva. Para o atributo sabor a cultivar Verônica recebeu as melhores notas no nível de salinidade 1,53 e 5,55 dS m-1. Para a cultivar Pira Roxa a melhor nota foi atribuída para a alface produzida na água não salina. Para os demais atributos não houve diferença significativa nos diferentes níveis de salinidade. Com relação à intenção de compra, constatou-se que as alfaces cv. Verônica e Pira Roxa apresentaram boa aceitação de mercado. Os menores níveis de nitrato (1960 mg kg-1 e 2620 mg kg-1 de massa de matéria fresca, da Verônica e Pira Roxa, respectivamente, foram relacionados à condutividade elétrica de 0,42 dS m-1, aumentando a salinidade da água para 7,43 dS m-1, o teor foliar de nitrato aumentou para 2500 mg kg-1 e 3420 mg kg-1 para as cultivares Verônica e Pira Roxa. Como o tempo de exposição da alface à salinidade em sistema hidropônico foi curto, em torno de 25 dias, não se verificou sintomas de deficiência nutricional e toda alface foi classificada como apropriada para consumo humano.This study aimed to evaluate the content of nutrients and nitrate and perform sensory analysis of lettuce in hydroponic system under saline water. The experiment was carried out in a greenhouse from December, 2007 to January, 2008, in Piracicaba. The experimental design was randomized blocks and factorial scheme (five salinity levels obtained with the addition of NaCl that resulted in different electrical conductivities of the water (dS m-1: 0.42, 1.53, 3.52, 5.55, 7.43 and two cultivas of lettuce (Veronica and Pira Roxa. The evaluations were: sensory analysis applying hedonic scale and through this, which sample presented the best and the least taste, the purchase intent and consumption, nitrate, absorption of nutrients by leaves and determination of nutrients in the nutrient solution. For the attribute of cultivars, Veronica received the highest marks in salt level 1.53 and 5.55 dS m-1. For cultivar Pira Roxa was awarded the best grade for lettuce grown in non-saline water. For other attributes there was no significant difference in levels of salinity. To purchase intention, it was found that cv. Verônica and Pira Roxa had good market acceptance. The lowest levels of nitrate (1960 mg kg-1 and 2620 mg kg-1 fresh weight of Verônica and Pira Roxa, respectively, were related to the electrical conductivity of 0.42 dS m-1, increasing water salinity to 7.43 dS m-1, the leaf content of nitrate increased to 2500 mg kg-1 and 3420 mg kg-1 for the cultivars Verônica and Pira Roxa. As the time of exposure to salt in a hydroponic system was short, around 25 days, there were no symptoms of nutrient deficiency and whole lettuce was classified as suitable for human consumption.

  11. VARIATION FOR TIPBURN RESISTANCE IN LETTUCE

    Science.gov (United States)

    Tipburn (TB) is a physiological disorder that results in necrosis along the margins of lettuce leaves. The disorder is objectionable to consumers and reduces the shelf life of whole and minimally processed lettuce. The objectives were to 1) determine the variation for tipburn resistance in iceberg, ...

  12. Relación porosidad-retención de humedad en mezclas de sustratos y su efecto sobre variables respuesta en plántulas de lechuga / Porosity-water retention relationship in substrate mixtures and its effect on response variables in lettuce seedlings

    Scientific Electronic Library Online (English)

    Ma. Del Carmen, Gutiérrez-Castorena; Jorge, Hernández Escobar; Carlos Alberto, Ortiz-Solorio; Rosa, Anicua Sánchez; Ma. Encarnación, Hernández Lara.

    2011-12-01

    Full Text Available Se estudió la relación entre la porosidad, el tamaño y distribución de partícula (1-2 mm y 2-3.36 mm) con la retención de humedad para diferentes mezclas de materiales: fibra de coco (Fc): piedra (P) o tezontle (T), combinados en proporciones variables (0:100, 25:75, 50:50, 75:25 y 100:0 v/v). Ademá [...] s, se analizó el efecto de la combinación Fc:P con un tamaño de partícula (1-2 mm) sobre variables respuesta en plántulas de lechuga var. Summertime. Se determinó la curva de retención de humedad. Los tipos de poros y el patrón de distribución de las partículas de las mezclas, se analizaron a través de secciones delgadas y la porosidad se cuantificó con un analizador de imágenes. Los resultados mostraron que las mezclas Fc:T y Fc:P (75:25 v/v), presentaron la mayor capacidad de retención de humedad gravimétrica (230 %) y volumétrica (98 %). Además, un sistema de poros heterogéneo o anisotrópico (macro y micro), y una distribución en bandas, que permitieron percolación y retención de humedad óptima para el desarrollo de las plántulas de lechuga, expresada en las mejores variables respuesta y calidad del cepellón. En contraste, el resto de las mezclas con un sistema de poros homogéneo o isotrópico, ya sea de poros de empaquetamiento simple o compuesto, y una distribución básica aleatoria de partículas, generaron más percolación o más retención de humedad, que limitaron el crecimiento de las plántulas. La micromorfología puede ser útil para comprender las propiedades físicas de los sustratos al determinar directamente el tipo, tamaño y continuidad de los poros, características que afectan la disponibilidad de agua-aire. Abstract in english The relationship among porosity, size and particle distribution (1-2 mm and 2-3.36 mm) with water retention for different mixtures of materials: coir (Fc), stone (P) or volcanic stone (T), combined in variables proportions (0:100, 25:75, 50:50, 75:25 and 100:0 v/v) was studied. The effect of the com [...] bination Fc:P with a particle size (1-2 mm) on response variables in lettuce seedlings var. Summertime was analyzed. The water retention curve was determined. The types of pores and the particle distribution pattern of the mixtures was analyzed though thin sections. Porosity was quantified using an image analyzer. Results showed that Fc:T and Fc:P mixtures (75:25 v/v), showed the highest volumetric (98 %) and gravimetric (230 %) water retention capacity, as well as an anisotropic or heterogeneous pore system (macro and micro), and a band distribution, that allowed percolation and optimal water retention for the development of lettuce seedlings, represented in the best response variables and quality of root ball. In contrast, the rest of the mixture with an isotropic or homogeneous pore system, either simple or compound packing pores, and a basic random distribution of particles, generating more percolation or more water retention, that limited the growth of seedlings. Micromorphology can be useful for understanding the physical properties of the substrates by directly determining the type, size and continuity of pores, characteristics that affect water-air availability.

  13. Uptake of cadmium by cress, lettuce and tomato in Cd-contaminated soil

    Directory of Open Access Journals (Sweden)

    J. Abedi-Koupai

    2015-06-01

    Full Text Available Increasing of water consumption and demand for irrigation water in agriculture has led to an increase in reuse of treated, or even raw, municipal and industrial wastewater in many countries. Heavy metals (HMs in these unconventional waters are one of the sources of pollution of water, soil and plant. HM toxicity in plants may eventually cause disturbances in plant growth. Accumulation of HMs in plants has health problems for human beings and animals which consume these plants. In this research, uptake of cadmium (Cd by three vegetables (cress (Lepidium sativum L., lettuce (Lactuca sativa L. and tomato (Solanum lycopersicum L. from a contaminated soil was studied. The experimental design was completely randomized. For each plant, two soil treatments (control soil and contaminated soil by 100 mg/L Cd and five replications were considered. After planting, growing and harvesting, and preparation of the samples, Cd uptake in roots and shoots was measured. Results showed that mean Cd uptake by all three plants was significantly different from the control treatment. Maximum uptake of Cd belonged to tomato, whereas lettuce had the lowest uptake. Transfer coefficient of Cd from soil into cress, lettuce and tomato was 1.3, 0.33 and 0.65, respectively. Although transfer coefficient of Cd to lettuce is lower than the other two plants, but consumption of lettuce per person is much greater than cress. Hence, irrigation management of polluted wastewater is important.

  14. The influence of light intensity and photoperiod on duckweed biomass and starch accumulation for bioethanol production.

    Science.gov (United States)

    Yin, Yehu; Yu, Changjiang; Yu, Li; Zhao, Jinshan; Sun, Changjiang; Ma, Yubin; Zhou, Gongke

    2015-01-01

    Duckweed has been considered as a valuable feedstock for bioethanol production due to its high biomass and starch production. To investigate the effects of light conditions on duckweed biomass and starch production, Lemna aequinoctialis 6000 was cultivated at different photoperiods (12:12, 16:8 and 24:0h) and light intensities (20, 50, 80, 110, 200 and 400?molm(-2)s(-1)). The results showed that the duckweed biomass and starch production was increased with increasing light intensity and photoperiod except at 200 and 400?molm(-2)s(-1). Considering the light cost, 110?molm(-2)s(-1) was optimum light condition for starch accumulation with the highest maximum growth rate, biomass and starch production of 8.90gm(-2)day(-1), 233.25gm(-2) and 98.70gm(-2), respectively. Moreover, the results suggested that high light induction was a promising method for duckweed starch accumulation. This study provides optimized light conditions for future industrial large-scale duckweed cultivation. PMID:25841186

  15. Productivity of duckweed (Lemna minor as alternative forage feed for livestock in different light intensities

    Directory of Open Access Journals (Sweden)

    Uti Nopriani

    2015-12-01

    Full Text Available Duckweed (Lemna minor is a small aquatic plant that grow and float in water and spread extensively. Lemna minor is potential as a source of high quality forage. This study aimed to determine optimal light intensity on Lemna minor to generate maximum productivity. Parameters observed were physical-biological and chemical characteristics of the media (pH value, temperature, cover area, decreased of media volume, BOD, COD, nitrate, nitrite and phosphate, plant growth acceleration (number of shoots, leaf diameter and chlorophyll-a, biomass production, doubling time of cover area and the number of daughters. This study was done based on a completely randomized design with 4 levels of shading. While treatment was: without shading, shading 30%, shading 50% and shading 70% using paranet shade. Each treatment consisted of 4 replications. Result showed that the productivity of Lemna minor included the number of daughters, chlorophyll-a, biomass production, cover area, absorbed phosphate and doubling time the number of daughters reached the highest level without shading treatment (1007,21-2813,57 lux. The decrease of intensity of light, the increase the diameter of leaf. Decrease of media volume was positively correlated to size of cover area. Biomass production influenced by a wide doubling time of cover area and number of daughters.

  16. Efeito de pontas de pulverização e de arranjos populacionais de plantas de Eichhornia crassipes e Salvinia auriculata na deposição de calda de pulverização sobre plantas de Pistia stratiotes Effect of spray tips and water hyacinth and water lettuce plant population arrangements of watermoss plant spray mix deposition

    Directory of Open Access Journals (Sweden)

    S.R. Marchi

    2009-06-01

    Full Text Available Este trabalho teve por objetivo avaliar o depósito de calda pulverizada por dois tipos de pontas de pulverização sob plantas de alface-d'água (Pistia stratiotes dispostas em diferentes arranjos populacionais com plantas de aguapé (Eichhornia crassipes e salvínia (Salvinia auriculata. Para isso, foi conduzido um experimento em condições de caixas-d'água em delineamento experimental inteiramente casualizado, com quatro repetições. Os tratamentos estiveram dispostos em esquema fatorial 2 x 8, sendo dois tipos de pontas de pulverização (ConeJet TXVK-8 e TeeJet DG 11002 VS e oito proporções entre as plantas aquáticas, a saber: dominância total da área correspondente a 100% de cobertura da caixa-d'água pelas plantas de alface-d'água; e as proporções entre plantas de alface-d'água e plantas de aguapé ou salvínia a 75%:25%, 50%:50% e 25%:75%. Também foi utilizada uma densidade tripla, na qual as três espécies estiveram igualmente dispostas na proporção de 33,33%. Soluções dos corantes Amarelo Tartrasina FDC-5 a 3.500 ppm e Azul Brilhante FDC-1 a 1.000 ppm foram utilizadas como traçadores para as pontas TXVK-8 e DG 11002VS, respectivamente. A pulverização de ambas as soluções foi efetuada na mesma unidade experimental, com um intervalo de 30 minutos entre si, utilizando-se um pulverizador costal pressurizado com CO2, calibrado de modo a proporcionar um volume de aplicação aproximado de 200 L ha. Após a pulverização, as plantas presentes nos reservatórios foram lavadas com água destilada, até remoção total dos corantes. Os depósitos totais de calda foram estimados em ?L por planta, e os depósitos unitários, em ?L cm-2 de superfície foliar. O aumento na proporção de plantas de aguapé na associação proporcionou menores depósitos de calda de pulverização sobre as plantas de alface-d'água. Em contrapartida, o aumento na proporção de salvínia na associação propiciou maiores depósitos de calda de pulverização, independentemente do tipo de ponta de pulverização. A ponta TXVK-8 proporcionou depósitos unitários e totais de calda de pulverização superiores aos da ponta DG 11002VS.This study aimed to evaluate two types of nozzles (ConeJet TXVK-8 and TeeJet DG 11002 VS and the amount of spray mix deposited on water lettuce (Pistia stratiotes plants organized under different population arrangements with water hyacinth (Eichhornia crassipes and eared watermoss (Salvinia auriculata plants. In addition to a full-dominance proportion over the area, corresponding to 100% cover of the water tank by eared watermoss plants, arrangements were used with either water hyacinth or water lettuce at 75%:25%, 50%:50%, and 25%:75%. Triple density was also used, with the three species being equally displayed at a 33.33% proportion. Dye solutions of FD&C Yellow no. 5 at 3,500 ppm and FD&C Blue no. 1 at 1,000 ppm were used as spraying tracers for TXVK-8 and DG 11002 VS nozzles, respectively. Both solutions were sprayed at the same plot within 30 minute interval each through a CO2 pressured backpack knapsack calibrated to deliver a spray volume around 200 L ha-1 . Plants at reservoirs were flushed with distilled water until total removal of the dyes deposited on them. The total spray deposits were estimated in ?L per plant and the unitary deposits where estimated in ?L cm-2 of foliar surface. Increase in water hyacinth plant proportion in the arrangement resulted in lower spray deposition over water lettuce. Increase in water moss plant proportion in the arrangement provided higher spray depositions over water lettuce, independently of the nozzle type used. The TXVK-8 nozzles provided higher unitary and total spray depositions compared to the DG 11002 VS nozzle.

  17. Efeito de pontas de pulverização e de arranjos populacionais de plantas de Eichhornia crassipes e Salvinia auriculata na deposição de calda de pulverização sobre plantas de Pistia stratiotes / Effect of spray tips and water hyacinth and water lettuce plant population arrangements of watermoss plant spray mix deposition

    Scientific Electronic Library Online (English)

    S.R., Marchi; D., Martins; N.V., Costa; V.D., Domingos; L.A., Cardoso.

    2009-06-01

    Full Text Available Este trabalho teve por objetivo avaliar o depósito de calda pulverizada por dois tipos de pontas de pulverização sob plantas de alface-d'água (Pistia stratiotes) dispostas em diferentes arranjos populacionais com plantas de aguapé (Eichhornia crassipes) e salvínia (Salvinia auriculata). Para isso, f [...] oi conduzido um experimento em condições de caixas-d'água em delineamento experimental inteiramente casualizado, com quatro repetições. Os tratamentos estiveram dispostos em esquema fatorial 2 x 8, sendo dois tipos de pontas de pulverização (ConeJet TXVK-8 e TeeJet DG 11002 VS) e oito proporções entre as plantas aquáticas, a saber: dominância total da área correspondente a 100% de cobertura da caixa-d'água pelas plantas de alface-d'água; e as proporções entre plantas de alface-d'água e plantas de aguapé ou salvínia a 75%:25%, 50%:50% e 25%:75%. Também foi utilizada uma densidade tripla, na qual as três espécies estiveram igualmente dispostas na proporção de 33,33%. Soluções dos corantes Amarelo Tartrasina FDC-5 a 3.500 ppm e Azul Brilhante FDC-1 a 1.000 ppm foram utilizadas como traçadores para as pontas TXVK-8 e DG 11002VS, respectivamente. A pulverização de ambas as soluções foi efetuada na mesma unidade experimental, com um intervalo de 30 minutos entre si, utilizando-se um pulverizador costal pressurizado com CO2, calibrado de modo a proporcionar um volume de aplicação aproximado de 200 L ha. Após a pulverização, as plantas presentes nos reservatórios foram lavadas com água destilada, até remoção total dos corantes. Os depósitos totais de calda foram estimados em ?L por planta, e os depósitos unitários, em ?L cm-2 de superfície foliar. O aumento na proporção de plantas de aguapé na associação proporcionou menores depósitos de calda de pulverização sobre as plantas de alface-d'água. Em contrapartida, o aumento na proporção de salvínia na associação propiciou maiores depósitos de calda de pulverização, independentemente do tipo de ponta de pulverização. A ponta TXVK-8 proporcionou depósitos unitários e totais de calda de pulverização superiores aos da ponta DG 11002VS. Abstract in english This study aimed to evaluate two types of nozzles (ConeJet TXVK-8 and TeeJet DG 11002 VS) and the amount of spray mix deposited on water lettuce (Pistia stratiotes) plants organized under different population arrangements with water hyacinth (Eichhornia crassipes) and eared watermoss (Salvinia auric [...] ulata) plants. In addition to a full-dominance proportion over the area, corresponding to 100% cover of the water tank by eared watermoss plants, arrangements were used with either water hyacinth or water lettuce at 75%:25%, 50%:50%, and 25%:75%. Triple density was also used, with the three species being equally displayed at a 33.33% proportion. Dye solutions of FD&C Yellow no. 5 at 3,500 ppm and FD&C Blue no. 1 at 1,000 ppm were used as spraying tracers for TXVK-8 and DG 11002 VS nozzles, respectively. Both solutions were sprayed at the same plot within 30 minute interval each through a CO2 pressured backpack knapsack calibrated to deliver a spray volume around 200 L ha-1 . Plants at reservoirs were flushed with distilled water until total removal of the dyes deposited on them. The total spray deposits were estimated in ?L per plant and the unitary deposits where estimated in ?L cm-2 of foliar surface. Increase in water hyacinth plant proportion in the arrangement resulted in lower spray deposition over water lettuce. Increase in water moss plant proportion in the arrangement provided higher spray depositions over water lettuce, independently of the nozzle type used. The TXVK-8 nozzles provided higher unitary and total spray depositions compared to the DG 11002 VS nozzle.

  18. Occurrence and Partial Characterization of Lettuce big vein associated virus and Mirafiori lettuce big vein virus in Lettuce in Iran

    OpenAIRE

    Alemzadeh, E.; Izadpanah, K.

    2012-01-01

    Mirafiori lettuce big vein virus (MiLBVV) and lettuce big vein associated virus (LBVaV) were found in association with big vein disease of lettuce in Iran. Analysis of part of the coat protein (CP) gene of Iranian isolates of LBVaV showed 97.1–100 % nucleotide sequence identity with other LBVaV isolates. Iranian isolates of MiLBVV belonged to subgroup A and showed 88.6–98.8 % nucleotide sequence identity with other isolates of this virus when amplified by PCR primer pair MiLV VP. The occurren...

  19. 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.

  20. Replacement of Sesame Oil Cake by Duckweed (Lemna minor in Broiler Diet

    Directory of Open Access Journals (Sweden)

    M.U. Ahammad

    2003-01-01

    Full Text Available An experiment was conducted with 120, seven-day old Vencobb commercial broiler chick feeding ad libitum upto 42 days of age on 4 different iso-nitrogenous and iso-energetic diet formulated by replacing dietary sesame oil cake (SOC by duckweed (DW to have its effect on performance of broilers. Live weight, feed conversion and profitability increased when sesame oil cake was partially replaced by duck weed. Complete SOC replaced diet significantly reduced live weight gain, feed intake, feed conversion and profitability, as compared with partial replacement of SOC by duckweed and SOC based control diet. Partial replacement of SOC by DW did not affect survivability of broiler. So it might be concluded that replacement of costly SOC partially by cheaper unconventional DW in broiler diet resulted in increased profitability. Therefore, cheaper duckweed could be practiced in formulating economic balanced diet for broiler.

  1. Aplicação de doses de CO2 via água de irrigação na cultura da alface Application of doses of CO2 by means of irrigation water for lettuce

    Directory of Open Access Journals (Sweden)

    Tamara Maria Gomes

    2005-06-01

    Full Text Available A concentração de CO2 na atmosfera vem aumentado significativamente desde a revolução industrial, estando hoje próximo de 365 mmol mol-1, com tendência de aumento. Este trabalho teve como objetivo estudar a influência de doses crescentes de CO2 via água de irrigação por gotejamento sobre o crescimento, o desenvolvimento, a fotossíntese e a produtividade da alface cultivar Elisa, bem como seus efeitos sobre a condutividade elétrica. O experimento foi conduzido sob túneis plásticos, em delineamento experimental inteiramente casualizado. Os tratamentos foram compostos por doses de CO2: 0 (testemunha, 52; 155 e 310 kg ha-1, aplicadas via água de irrigação. As irrigações foram realizadas diariamente com base na evaporação do tanque classe A, corrigida pelo coeficiente da cultura e do tanque. O número de folhas e a matéria seca da parte aérea da planta foram influenciados pela aplicação de CO2 via água de irrigação, não ocorrendo o mesmo para matéria fresca e índice de área foliar. Os resultados indicaram a dose mensal de 153 kg ha-1 de CO2 como a mais adequada para ser empregada na cultura da alface via água de irrigação, com um aumento de aproximadamente 20,5% de produtividade, quando comparado à testemunha.Carbon dioxide concentration in the atmosphere has been increasing since the industrial revolution. Nowadays it is approximately 365 mmol mol-1, with a tendency to increase. The effect of CO2 dosis, supplied by drip irrigation on lettuce development, plants growth, photosynthesis and productivity, and also the effects on electrical conductivity were evaluated. The experiment was conduced under plastic tunnels in a completely randomized block design. The treatments included CO2 rates: 0 (control, 52; 155 and 310 kg ha-1. Water was delivered daily to plants in order to replace lost volumes by evapotranspiration, based on estimates from class A evaporation pan, corrected by the crop and tank coefficients (Kc and Kp, respectively. The CO2 use, via irrigation water, changed the leaves number and the shoot dry weight, but not the leaf area index and the fresh dry weight. The monthly use of 153 kg ha-1 of CO2, via irrigation water, is proper for lettuce since it increased the productivity in 20.5% when compared to the control.

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

    DEFF Research Database (Denmark)

    Keraita, Bernard; Konradsen, Flemming; Drechsel, Pay; Abaidoo, Robert C

    .66/day for the wet season and 1.49/day for the dry season. CONCLUSION: In combination with other measures for improving water quality, the measure can significantly reduce faecal contamination of lettuce during the dry season. However, it is not suitable for the wet season due to unfavourable conditions...... 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...

  3. Effects of duckweed (Lemna minor) as dietary fishmeal substitute for silver barb (Barbodes gonionotus Bleeker)

    OpenAIRE

    Noor, J.; M. A. HOSSAIN; Bari, M.M.; K.M. Azimuddin

    2000-01-01

    A 60-day long growth trial was conducted to evaluate the suitability of duckweed Lemna minor as dietary fish meal substitute for silver barb (Borbodes gonionotus Bleeker). Five iso-nitrogenous diets were formulated to contain 35% protein and each treatment had three replicates with 15 fish in each aquarium with a mean initial weight of 1.5 ± 0.2 g. Duckweed was used in the experiment to replace 10, 20, 30 and 35% of the dietary fish meal in diet 2, 3, 4 and 5 respectively. Fish meal was use...

  4. GROWTH RESPONSE OF THE DUCKWEED LEMNA MINOR TO HEAVY METAL POLLUTION

    OpenAIRE

    N. Khellaf ? M. Zerdaoui

    2009-01-01

    To assess the tolerance and effect of heavy metals pollution on the duckweed Lemna minor, the aquatic plants were exposed to different concentrations of copper (Cu), nickel (Ni), cadmium (Cd) and zinc (Zn) in a quarter Coïc and Lessaint solution at pH = 6.1 (± 0.1) and under a daily regime of 16 h light (101 ?mol/m2.s1). Copper at 0.2 mg/L and nickel at 0.5 mg/L promoted the growth of Lemna fronds. At higher concentrations, Cu and Ni inhibited the growth of duckweed; the EC50 (concentration c...

  5. Antimicrobial activity of plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes on fresh lettuce.

    Science.gov (United States)

    Kim, Sung-Youn; Kang, Dong-Hyun; Kim, Jin-Ki; Ha, Yong-Geun; Hwang, Ju Young; Kim, Taewan; Lee, Seon-Ho

    2011-01-01

    Plant extracts have been found to be effective in reducing microorganisms. This study evaluated antimicrobial activity of 12 plant extracts against Salmonella Typhimurium, Escherichia coli O157:H7, and Listeria monocytogenes by using a disk diffusion assay, and Syzygium aromaticum (clove) showed the highest inhibitory effect. To investigate the efficacy of clove extract that inactivates pathogens on lettuce, inoculated lettuce with S. Typhimurium, E. coli O157:H7, and L. monocytogenes was treated with diluted clove extracts or distilled water for 0, 1, 3, 5, and 10 min. Clove extract treatment significantly reduced populations of the 3 tested pathogens from the surface of lettuce. Practical Application: This result indicated that clove extract is a useful antimicrobial agent to reduce the microbial level of foodborne pathogens on fresh lettuce. It also might be a natural antimicrobial for reducing or replacing chemical sanitizers in food preservation. PMID:21535692

  6. 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

  7. ROMAINE LETTUCE (LACTUCA SATIVA L.) BREEDING LINES WITH RESISTANCE TO LETTUCE DIEBACK CAUSED BY TOMBUSVIRUSES.

    Science.gov (United States)

    The soilborne disease lettuce dieback is caused by at least two members of the virus family Tombusviridae, lettuce necrotic stunt virus (LNSV) and tomato bushy stunt virus (TBSV). Dieback causes severe stunting and chlorosis, mottling, and necrosis in o older leaves, and can cause complete crop loss...

  8. Potential sources of genetic resistance in lettuce to the lettuce aphid, Nasanovia ribisnigri (Mosely) (Homoptera: Aphididae)

    Science.gov (United States)

    Lettuce aphid, Nasanovia ribisnigri (Mosely) (Homoptera:Aphididae), is an economically important pest of lettuce (Lactuca sativa L.). High-level resistance was found in a wild relative, Lactuca virosa L. accession PIVT-280, and transferred to European cultivars. This resistance is conditioned by the...

  9. Deposição de calda de pulverização sobre plantas de salvínia em função de pontas de pulverização e arranjos populacionais entre plantas de Aguapé e Alface-D'Água Spray deposition on water fern plants in function of nozzle tips and population arrangements with water Hyacinth and Water Lettuce plants

    Directory of Open Access Journals (Sweden)

    S.R. Marchi

    2011-03-01

    Full Text Available Este trabalho teve como objetivo avaliar o depósito de calda pulverizada por dois tipos de pontas de pulverização sobre plantas de Salvinia auriculata dispostas em diferentes arranjos populacionais com plantas de Eichhornia crassipes e Pistia stratiotes. Um experimento foi conduzido em condições de caixas-d'água em delineamento inteiramente casualizado, com quatro repetições. Os tratamentos foram dispostos em esquema fatorial 2 x 8, sendo dois tipos de pontas de pulverização (ConeJet TXVK-8 e TeeJet DG 11002 VS e oito proporções entre as plantas aquáticas, a saber: dominância total da área de cobertura da caixa-d'água pelas plantas de salvínia (100%; e as proporções entre plantas de salvínia e de aguapé ou alface-d'água a 75%:25%, 50%:50% e 25%:75%. Também foi utilizada uma densidade tripla, na qual as três espécies estiveram igualmente dispostas na proporção de 33%. Soluções dos corantes Amarelo Tartrasina FDC-5 a 3.500 ppm e Azul Brilhante FDC-1 a 1.000 ppm foram utilizadas como traçadores para as pontas TXVK-8 e DG 11002VS, respectivamente. A pulverização das soluções foi efetuada na mesma unidade experimental, com intervalo de 30 minutos entre si, com auxílio de um pulverizador costal pressurizado com CO2, calibrado de modo que proporcionasse volume de aplicação aproximado de 200 L ha-1. Não foram observadas diferenças estatísticas entre os tipos de pontas de pulverização nas diferentes proporções estudadas, exceto para depósitos totais de calda de pulverização nas plantas na condição de dominância total da salvínia, uma vez que a ponta ConeJet TXVK-8 foi superior à TeeJet DG 11002 VS. Os valores dos depósitos diminuíram com o aumento da proporção de plantas de aguapé na associação e foram na condição em que 25% de plantas de salvínia estiveram associadas a 75% de plantas de aguapé. A presença da espécie alface-d'água não influenciou a deposição de gotas sobre as folhas de salvínia.This study aimed to evaluate two types of spray tips (ConeJet TXVK-8 and TeeJet DG 11002 VS and the amount of spray mix deposited on Salvinia auriculata plants organized under different population arrangements with Eichhornia crassipes and Pistia stratiotes plants. In addition to a full-dominance proportion over the area, corresponding to 100% cover of the water tank by eared water moss plants, arrangements with either water hyacinth or water lettuce were made at 75%:25%, 50%:50%, and 25%:75%. A triple density, in which the three species were equally disposed at a 33.33% proportion, was also used. Dye solutions of FD&C Yellow no. 5 at 3,500 ppm and FD&C Blue no.1 at 1,000 ppm were used, as spraying tracers for TXVK-8 and DG 11002 VS nozzles, respectively. Both solutions were sprayed at the same plot within a 30-minute interval each, through a CO2 pressured backpack, calibrated to deliver a spray volume of around 200 L ha-1. The total spray deposits were estimated in mL per plant and the unit deposits in mL cm² of foliar surface. No significant differences were observed between the nozzle tips used at different population arrangements, except total spray mix deposited on plants at 100% of eared water moss dominance proportion, with ConeJet TXVK-8, providing superior spray mix deposition, compared with TeeJet DG 11002 VS. The highest spray mix deposition was obtained under 100% of salvínia dominance. However, the spray mix quantity decreased with increase of water hyacinth in the proportion and reached the lowest value when 25% of eared water moss plants were associated with 75% of water hyacinth plants. The presence of water lettuce did not influence spray mix deposition over eared water moss plants.

  10. GROWTH RESPONSE OF THE DUCKWEED LEMNA MINOR TO HEAVY METAL POLLUTION

    Directory of Open Access Journals (Sweden)

    N. Khellaf ? M. Zerdaoui

    2009-07-01

    Full Text Available To assess the tolerance and effect of heavy metals pollution on the duckweed Lemna minor, the aquatic plants were exposed to different concentrations of copper (Cu, nickel (Ni, cadmium (Cd and zinc (Zn in a quarter Coïc and Lessaint solution at pH = 6.1 (± 0.1 and under a daily regime of 16 h light (101 ?mol/m2.s1. Copper at 0.2 mg/L and nickel at 0.5 mg/L promoted the growth of Lemna fronds. At higher concentrations, Cu and Ni inhibited the growth of duckweed; the EC50 (concentration causing 50% inhibition were 0.47 mg/L for Cu and 1.29 mg/L for Ni. Cadmium and zinc decreased by 50% the growth of fronds when the medium contained respectively 0.64 and 5.64 mg/L (EC50. Duckweed tolerated Cu, Ni, Cd and Zn at concentrations of 0.4, 3.0, 0.4 and 15.0 mg/L respectively without showing any visible signs of toxicity (chlorosis, frond disconnection and necrosis. On the basis of visible symptoms and the EC50 values, the toxicity of the metals on Lemna. minor was in decreasing order of damage: Cu > Cd > Ni > Zn. It was concluded that the duckweed Lemna. minor is very sensitive to copper and cadmium pollution.

  11. Relative in vitro growth rates of duckweeds (Lemnaceae) - the most rapidly growing higher plants.

    Science.gov (United States)

    Ziegler, P; Adelmann, K; Zimmer, S; Schmidt, C; Appenroth, K-J

    2015-01-01

    Relative growth rates (RGR), doubling times (DT) and relative weekly yields (RY) of 39 clones (ecotypes) from 13 species representing all five genera of duckweeds were determined under standardised cultivation conditions. RGR ranged overall from 0.153 to 0.519 day(-1) , DT from 1.34 to 4.54 days and RY from 2.9 to 37.8 week(-1) . The RGR and RY data can be compared directly to other published findings to only a limited extent on account of missing clonal designations for and limited accessibility to previously investigated clones, as well as the use of different data denominators. However, they are consistent with the published results of other comparative duckweed studies of similar scope in showing that RGR does not vary primarily at the level of the genus or species, but rather reflects the adaptation of individual clones to specific local conditions. The RGR data support the widely held assumption that duckweeds can grow faster than other higher plants and that they can thus surpass land-based agricultural crops in productivity. Duckweeds are highly promising for the production of biomass for nutrition and energy, but extensive clonal comparison will be required to identify the most suitable isolates for this purpose. PMID:24803032

  12. Suitability of duckweed (Lemna minor as feed for fish in polyculture system

    Directory of Open Access Journals (Sweden)

    M.Z.H. Talukdar

    2012-06-01

    Full Text Available In the present study, we conducted an experiment to evaluate the effects of duckweed (Lemna minor as feed on fish production in polyculture. The experiment had 2 treatments where in treatment 1 (T1 ponds were supplied with duckweed as feed and in treatment 2 (T2 ponds were kept as control (without supply of duckweed. Average survival rates in T1 and T2 were 90 and 89%, respectively. The specific growth rates (SGR were higher in T1. Calculated net production in T1 was 6.25 tons ha.-1 yr.-1 and in T2 was 2.84 tons ha.-1 yr.-1. The ranges of physico-chemical parameters analyzed were within the productive limit and more or less similar in all the ponds under both treatments during the experimental period. There were 24 genera of phytoplankton under 5 major groups and 10 genera of zooplankton under 3 major groups found in the experimental ponds. The net production in T1 was significantly higher than that of T2 indicated the use of duckweed as feed for fishes is economically sustainable in polyculture.

  13. Expression and Characterization of Acidothermus celluloyticus E1 Endoglucanase in Transgenic Duckweed Lemna minor 8627

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.; Cheng, J. J.; Himmel, M. E.; Skory, C. D.; Adney, W. S.; Thomas, S. R.; Tisserat, B.; Nishimura, Y.; Yamamoto, Y. T.

    2007-01-01

    Endoglucanase E1 from Acidothermus cellulolyticus was expressed cytosolically under control of the cauliflower mosaic virus 35S promoter in transgenic duckweed, Lemna minor 8627 without any obvious observable phenotypic effects on morphology or rate of growth. The recombinant enzyme co-migrated with the purified catalytic domain fraction of the native E1 protein on western blot analysis, revealing that the cellulose-binding domain was cleaved near or in the linker region. The duckweed-expressed enzyme was biologically active and the expression level was up to 0.24% of total soluble protein. The endoglucanase activity with carboxymethylcellulose averaged 0.2 units mg protein{sup -1} extracted from fresh duckweed. The optimal temperature and pH for E1 enzyme activity were about 80 C and pH 5, respectively. While extraction with HEPES (N-[2-hydroxyethyl]piperazine-N{prime}-[2-ethanesulfonic acid]) buffer (pH 8) resulted in the highest recovery of total soluble proteins and E1 enzyme, extraction with citrate buffer (pH 4.8) at 65 C enriched relative amounts of E1 enzyme in the extract. This study demonstrates that duckweed may offer new options for the expression of cellulolytic enzymes in transgenic plants.

  14. Short-duration exposure to radiofrequency electromagnetic radiation alters the chlorophyll fluorescence of duckweeds (Lemna minor).

    Science.gov (United States)

    Senavirathna, Mudalige Don Hiranya Jayasanka; Takashi, Asaeda; Kimura, Yuichi

    2014-12-01

    Plants growing in natural environments are exposed to radiofrequency electromagnetic radiation (EMR) emitted by various communication network base stations. The environmental concentration of this radiation is increasing rapidly with the congested deployment of base stations. Although numerous scientific studies have been conducted to investigate the effects of EMR on the physiology of humans and animals, there have been few attempts to investigate the effects of EMR on plants. In this study, we attempted to evaluate the effects of EMR on photosynthesis by investigating the chlorophyll fluorescence (ChF) parameters of duckweed fronds. During the experiment, the fronds were tested with 2, 2.5, 3.5, 5.5 and 8?GHz EMR frequencies, which are not widely studied even though there is a potentially large concentration of these frequencies in the environment. The duckweed fronds were exposed to EMR for 30?min, 1?h and 24?h durations with electric field strength of 45-50?V/m for each frequency. The results indicated that exposure to EMR causes a change in the non-photochemical quenching of the duckweeds. The changes varied with the frequency of the EMR and were time-varying within a particular frequency. The temperature remained unchanged in the duckweed fronds upon exposure to EMR, which confirms that the effect is non-thermal. PMID:24131393

  15. Utilization of a duckweed bioassay to evaluate leaching of heavy metals in smelter contaminated soils

    Energy Technology Data Exchange (ETDEWEB)

    Youngman, A.L.; Lydy, M.J. [Wichita State Univ., KS (United States). Dept. of Biological Sciences; Williams, T.L. [Laidlaw Environmental Services, Wichita, KS (United States)

    1998-12-31

    The purpose of this study was to determine whether a duckweed bioassay could be used to evaluate the downward migration of heavy metals in smelter soils. The duckweed bioassay was initially used to evaluate elutriates prepared from samples of smelter soils. These initial tests verified that the elutriates would elicit toxic responses. Elutriate testing was followed with an evaluation of leachate from untreated soil cores or soil cores that had been amended with organic matter either unplanted or planted to a grass-forb seed mixture. There was an inverse linear relationship between heavy-metal concentrations in leachate and NOEC and IC{sub 50} values expressed as percentages among all soil cores. Based on these preliminary duckweed bioassays, there were no differences between soil types or organic amended or non-amended soil, but leachate from vegetated soil cores were less toxic than were leachates from non-vegetated soil cores. Overall, the duckweed bioassays were useful in detecting heavy metal availability in elutriate and leachate samples from smelter soils.

  16. Genetic structure of duckweed population of Spirodela, Landoltia and Lemna from Lake Tai, China.

    Science.gov (United States)

    Tang, Jie; Zhang, Fei; Cui, Weihua; Ma, Jiong

    2014-06-01

    Duckweed is widely used in environmental biotechnology and has recently emerged as a potential feedstock for biofuels due to its high growth rate and starch content. The genetic diversity and composition of a natural duckweed population in genera Spirodela, Landoltia and Lemna from Lake Tai, China, were investigated using probabilistic analysis of multilocus sequence typing (MLST). The 78 strains were categorized into five lineages, among which strains representing L. aequinoctialis and S. polyrhiza were predominant. Among the five lineages, interlineage transfers of markers were infrequent and no recombination was statistically detected. Tajima's D tests determined that all loci are subject to population bottlenecks, which is likely one of the main reasons for the low genetic diversity observed within the lineages. Interestingly, strains of L. turionifera are found to contain small admixture from L. minor, providing rare evidence of transfer of genetic materials in duckweed. This was discussed with respect to the hypothesis that a cross of these two gave rise to L. japonica. Moreover, the conventional maximum-likelihood phylogenetic analysis clearly recognized all the species in the three genera with high bootstrap supports. In conclusion, this work offers a basic framework for using MLST to characterize Spirodela, Landoltia and in particular Lemna strains at the species level, and to study population genetics and evolution history of natural duckweed populations. PMID:24663442

  17. Selenium speciation using HPLC-ICP-MS in selenium-enriched duckweed (Lemna minor)

    International Nuclear Information System (INIS)

    Complete text of publication follows. The HPLC-ICP-MS for speciation analysis of selenium was developed and applied to selenium enriched duckweed (Lemna minor). The duckweed in Hoagland's E-medium containing Se from sodium selenate in the concentration of 0, 5, 10, 15 and 20 mg/L was cultured. The effect of selenium supplemented concentration and cultured periods (0-8 days) were studied. The results revealed that the optimum concentration of supplemented Se and cultured period were 10 mg/L and 6 days, respectively. The Se-enriched duckweed samples (whole plant) were dried and homogenized. The 0.1 M HCl in 10% methanol extracts were analyzed. Selenium speciation was carried out by ion-pairing HPLC (2.5 mM sodium 1-butanesulfonate, 8 mM tetramethyl ammonium hydroxide and trifluoro acetic acid at pH 4.5). The organic selenium species found in the extract was selenomethylcysteine, selenomethionine and others unknown species. The percentage contributions of selenium in both species of the total selenium were 0.6 and 1.0%, respectively. It can be seen that Se-enriched duckweed can feasibility be a dietary source of Se. The authors would like to thank Center of Excellence for Innovation in Chemistry (PERCH-CIC), Commission on Higher Education, Ministry of Education for financial support.

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

    International Nuclear Information System (INIS)

    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

  19. 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.

  20. Engineering Corynebacterium crenatum to produce higher alcohols for biofuel using hydrolysates of duckweed (Landoltia punctata) as feedstock

    OpenAIRE

    Su, Haifeng; Jiang, Juan; Lu, Qiuli; Zhao, Zhao; Xie, Tian; Zhao, Hai; Wang, Maolin

    2015-01-01

    Early trials have demonstrated great potential for the use of duckweed (family Lemnaceae) as the next generation of energy plants for the production of biofuels. Achieving this technological advance demands research to develop novel bioengineering microorganisms that can ferment duckweed feedstock to produce higher alcohols. In this study, we used relevant genes to transfer five metabolic pathways of isoleucine, leucine and valine from the yeast Saccharomyces cerevisiae into the bioengineered...

  1. Monitoring the influence of light intensity on the growth and mortality of duckweed (Lemna minor) through digital images processing

    OpenAIRE

    Tangou Tabou, Thierry; Baya, Dehenould Trésor; Musibono Eyul'Anki, Dieudonné; Vasel, Jean-Luc

    2013-01-01

    The growth of duckweed (Lemna minor), depending on biotic and abiotic factors (i.e. temperature, light intensity, photoperiod, pH, nutrients), is an important compartment of the treatment process in wastewater floating macrophytes ponds. Excess or shortage of this biomass might be responsible of the dysfunction of such ponds. Modeling these duckweed ponds through mass balances based on Petersen’s matrix should help in an optimal management of such facilities. This article focused on (i) the i...

  2. Clonal expansion of Verticillium dahliae in lettuce.

    Science.gov (United States)

    Gurung, S; Short, D P G; Atallah, Z K; Subbarao, K V

    2014-06-01

    Few studies in population biology have documented how structure and diversity of pathogens evolve over time at local scales. With the historical samples of Verticillium dahliae available from lettuce, we investigated the structure and diversity of this pathogen in time and space. Three hundred twenty-nine V. dahliae isolates from lettuce fields collected over 18 years were characterized with polymorphic microsatellite markers and polymerase chain reaction tests for race and mating type. Genetic variation within and among commercial lettuce fields in a single season was also investigated using an additional 146 isolates. Sixty-two haplotypes (HTs) were observed among the 329 isolates. A single HT was frequently observed over multiple years and locations (61.40%). Genetic diversity, allelic richness, and private allelic richness suggested a relatively recent clonal expansion. Race 1 (93.63%) and MAT1-2-1 (99.69%) were overwhelmingly represented among the isolates. Linkage disequilibrium was significant (P < 0.001) for all populations, suggesting limited sexual recombination in the sampled populations from lettuce. Populations from 2006, 2009, and 2010 had higher numbers of unique HTs, implying a recent introduction of novel HTs. We conclude that V. dahliae population from lettuce evaluated in this study is expanding clonally, consistent with an asexually reproducing pathogen, and the movement of clonal genotypes locally occurs over time. PMID:24476528

  3. Assessment, validation and deployment strategy of a two-barcode protocol for facile genotyping of duckweed species.

    Science.gov (United States)

    Borisjuk, N; Chu, P; Gutierrez, R; Zhang, H; Acosta, K; Friesen, N; Sree, K S; Garcia, C; Appenroth, K J; Lam, E

    2015-01-01

    Lemnaceae, commonly called duckweeds, comprise a diverse group of floating aquatic plants that have previously been classified into 37 species based on morphological and physiological criteria. In addition to their unique evolutionary position among angiosperms and their applications in biomonitoring, the potential of duckweeds as a novel sustainable crop for fuel and feed has recently increased interest in the study of their biodiversity and systematics. However, due to their small size and abbreviated structure, accurate typing of duckweeds based on morphology can be challenging. In the past decade, attempts to employ molecular barcoding techniques for species assignment have produced promising results; however, they have yet to be codified into a simple and quantitative protocol. A study that compiles and compares the barcode sequences within all known species of this family would help to establish the fidelity and limits of this DNA-based approach. In this work, we compared the level of conservation between over 100 strains of duckweed for two intergenic barcode sequences derived from the plastid genome. By using over 300 sequences publicly available in the NCBI database, we determined the utility of each of these two barcodes for duckweed species identification. Through sequencing of these barcodes from additional accessions, 30 of the 37 known species of duckweed could be identified with varying levels of confidence using this approach. From our analyses using this reference dataset, we also confirmed two instances where mis-assignment of species has likely occurred. Potential strategies for further improving the scope of this technology are discussed. PMID:25115915

  4. Impact of biosolids and wastewater effluent application to agricultural land on corticosterone content in lettuce plants.

    Science.gov (United States)

    Shargil, Dorit; Fine, Pinchas; Gerstl, Zev; Nitsan, Ido; Kurtzman, Daniel

    2016-01-15

    We studied corticosterone occurrence in lettuce plants grown on three biosolids amended soils under irrigation with either tap water or secondary wastewater effluent. Corticosterone was examined as it has possible implications for human health. It is a major glucocorticoid, and as such has an effect on regulation of metabolism, immune functions and stress response. The plants were grown in 220-L lysimeters packed with 3 soils which represent a wide range of physicochemical properties. Lettuce was grown in cycles (two in summer and two in winter) during 3years, and in every spring season the sludges were re-applied. Corticosterone was quantified using ELISA and LCMS, and was found in the biosolids, tap water, wastewater effluent and lettuce plants. The respective ranges of concentrations were: 11-92ngg(-1), 0.5-1.6ngL(-1), 4.2-4.7ngL(-1); and 1-900ngg(-1) dry weight. A positive relationship was found between corticosterone concentrations in winter-grown lettuces and the plants fresh weight. The corticosterone content of the plants did not correspond with either the type of irrigation water or the biosolids type and rate of application or the soil properties. PMID:26437348

  5. Comparison of lettuce diseases and yield under subsurface drip and furrow irrigation.

    Science.gov (United States)

    Subbarao, K V; Hubbard, J C; Schulbach, K F

    1997-08-01

    ABSTRACT Subsurface drip and furrow irrigation were compared on lettuce (Lactuca sativa) cvs. Salinas and Misty Day for yield and incidence and severity of three important diseases of lettuce in the Salinas Valley, CA. Experiments were conducted between 1993 and 1995 during the spring and fall seasons. The diseases examined included lettuce drop (Sclerotinia minor), downy mildew (Bremia lactucae), and corky root (Rhizomonas suberifaciens). Replicated plots of subsurface drip and furrow irrigation were arranged in a randomized complete-block design. All plants were inoculated with S. minor at the initiation of the experiment during the 1993 spring season. Plots were not inoculated for downy mildew and corky root during any season nor were the plots reinoculated with S. minor. During each season, all plots were sprinkler irrigated until thinning, and subsequently, the irrigation treatments were begun. The furrow plots were irrigated once per week, and the drip plots received water twice per week. The distribution of soil moisture at two soil depths (0 to 5 and 6 to 15 cm) at 5, 10, and 15 cm distance on either side of the bed center in two diagonal directions was significantly lower in drip-irrigated compared with furrow-irrigated plots. Plots were evaluated for lettuce drop incidence and downy mildew incidence and severity at weekly intervals until harvest. Corky root severity and yield components were determined at maturity. Lettuce drop incidence and corky root severity were significantly lower and yields were higher in plots under subsurface drip irrigation compared with furrow irrigation, regardless of the cultivar, except during the 1994 fall season. Incidence and severity of downy mildew were not significantly different between the two irrigation methods throughout the study. The differential microclimates created by the two irrigation treatments did not affect downy mildew infection, presumably because the mesoclimate is usually favorable in the Salinas Valley. Subsurface drip irrigation is a viable, long-term strategy for soilborne disease management in lettuce in the Salinas Valley. PMID:18945057

  6. NITRATE CONTENT IN LETTUCE (Lactuca sativa L.) AFTER FERTILIZATION WITH SEWAGE SLUDGE AND TREATED WASTEWATER IRRIGATION

    OpenAIRE

    CASTRO BARRILERO, ELENA; MAÑAS RAMIREZ, PILAR; DE LAS HERAS IBAÑEZ, JORGE

    2009-01-01

    Abstract Abstract A romaine type lettuce (Lactuca sativa L.) was cultivated during three crop seasons (spring 2005, spring 2006 and autumn-winter 2006) in the same soil in Alcazar de San Juan, Spain. Six plots of 36 m2 each, were set up in agricultural land. A drip irrigation system was used to water all plots: five plots with drinking water and one plot with wastewater from Wastewater Treatment Plant (WWTP) of Activated Sludge system. One drinking water irrigated plot was n...

  7. 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. PMID:22857515

  8. The influence of duckweed species diversity on biomass productivity and nutrient removal efficiency in swine wastewater.

    Science.gov (United States)

    Zhao, Zhao; Shi, Huijuan; Liu, Yang; Zhao, Hai; Su, Haifeng; Wang, Maolin; Zhao, Yun

    2014-09-01

    The effect of temperature, light intensity, nitrogen and phosphorus concentrations on the biomass and starch content of duckweed (Landoltia punctata OT, Lemna minor OT) in monoculture and mixture were assessed. Low light intensity promoted more starch accumulation in mixture than in monoculture. The duckweed in mixture had higher biomass and nutrient removal efficiency than those in monoculture in swine wastewater. Moreover, the ability of L. punctata C3, L. minor C2, Spirodela polyrhiza C1 and their mixtures to recovery nutrients and their biomass were analyzed. Results showed that L. minor C2 had the highest N and P content, while L. punctata C3 had the highest starch content, and the mixture of L. punctata C3 and L. minor C2 had the greatest nutrient removal rate and the highest biomass. Compared with L. punctata C3 and L. minor C2 in monoculture, their biomass in mixture increased by 17.0% and 39.8%, respectively. PMID:24998479

  9. Occurrence of macrophyte monocultures in drainage ditches relates to phosphorus in both sediment and water

    OpenAIRE

    Zuidam, J.P. van; Peeters, E.T.H.M.

    2013-01-01

    Monocultures of functional equivalent species often negatively affect nutrient cycling and overall biodiversity of aquatic ecosystems. The importance of water and sediment nutrients for the occurrence of monocultures was analysed using field data from drainage ditches. Ranges of nutrients were identified that best explained the occurrence of monocultures of Elodea nuttallii (Planch.) St. John (Waterweed type), monocultures of duckweed (Duckweed type) and the occurrence of a diverse submerged ...

  10. Stimulation of nitrogen removal in the rhizosphere of aquatic duckweed by root exudate components

    OpenAIRE

    Lu, Yufang; Zhou, Yingru; Nakai, Satoshi; Hosomi, Masaaki; Hailin ZHANG; Kronzucker, Herbert J.; Shi, Weiming

    2013-01-01

    Plants can stimulate bacterial nitrogen (N) removal by secretion of root exudates that may serve as carbon sources as well as non-nutrient signals for denitrification. However, there is a lack of knowledge about the specific non-nutrient compounds involved in this stimulation. Here, we use a continuous root exudate-trapping system in two common aquatic duckweed species, Spirodela polyrrhiza (HZ1) and Lemna minor (WX3), under natural and aseptic conditions. An activity-guided bioassay using de...

  11. NEW BIOLOGICAL DIETARY FEED SUPPLEMENT FOR LAYING HENS WITH MICROELEMENTS BASED ON DUCKWEED (LEMNA MINOR

    Directory of Open Access Journals (Sweden)

    Zuzanna Witkowska

    2012-01-01

    Full Text Available In this study the applicability of enriched duckweed (Lemna minor as a dietary supplement witch microelements is reported. In our previous studies, the technology of new feed additives with microelements based on duckweed biomass was elaborated. Here, we report the evaluation of the properties of a new product. The effect of duckweed enriched with microelements on the productivity parameters of laying hens was studied in zootechnical research. Birds feed was supplemented with duckweed enriched by biosorption process with microelements (Cu(II, Zn(II, Co(II, Cr(III. In the feeding experiment, laying hens were divided into four experimental groups and one control group. The feeding experiment was conducted for 41 days. Samples of egg yolk, albumen, eggshells, blood, feathers and droppings were collected and the content of metal ions was determined by Inductively Coupled Plasma-Optical Emission Spectrometer with ultrasonic nebulizer. The amount of a given microelement transferred into the egg yolk and egg white was calculated. The eggshells thicknesses were measured with micrometer screw. The research showed that enriched Lemna minor improved the egg quality parameters. In all experimental groups, the increase of eggshell thickness was observed. In three of four experimental groups of hens, fed with diet containing biological form of microelements (Co(II, Zn(II, Cr(III, the quantity of given microelement in the egg content increased. Therefore, the biosorption process can be applied not only for the supplementation of microelements in hens feed, but also to produce eggs biofortified with microelements-new functional food for human.

  12. Comparative study of two bioassays with weakened duckweed and yeast treated with homeopathic preparations

    OpenAIRE

    Ursula Wolf; Peter Heusser; Meinhard Simon; Claudia Scherr; Tim Jäger; Stephan Baumgartner

    2012-01-01

    In homeopathic basic research, the question as to the most adequate test systems and apt methodology is still open. This investigation examined the hypothesis that more complex organisms show stronger reactions to homeopathic remedies than less complex ones. We compared two Arsenic (As5+) stressed bioassays with duckweed (Lemna gibba, a multi-cellular autotrophic organism) and yeast (Saccharomyces cerevisiae, a single-cellular heterotrophic organism) regarding their response to home...

  13. Performance and Process Analysis of Duckweed-Covered Sewage Lagoons for High Strength Sewage:

    OpenAIRE

    Al-Nozaily, F.A.

    2001-01-01

    Duckweed (L g/fofoaj-covered sewage lagoons (DSLs) are low cost treatment systems, especially In warm climates (or seasons). This study attempts to assess DSL system as a new technology, contributing to the understanding of the different mechanisms in the system. DSLs could either replace complete waste stabilization ponds (WSPs), or be the second stage in an integrated WSP-DSL treatment system, which could then be used for purifying municipal wastewater, achieving suitable effluent for reuse...

  14. Increase of starch accumulation in the duckweed Lemna minor under abiotic stress

    OpenAIRE

    K. SOWJANYA SREE; KLAUS-J. APPENROTH

    2014-01-01

    Abiotic stresses often result in suppression of photosynthesis and plant growth. Using the duckweed species Lemna minor and subjecting these plants to abiotic stress viz., (1) application of heavy metals, (2) application of salt (NaCl), and (3) lack of phosphate, we showed that photosynthesis was inhibited to a lesser degree than plant growth. This became evident by detecting the accumulation of starch under these conditions: (1) Cadmium ions and other heavy metals induced the accumulation of...

  15. Replacement of Sesame Oil Cake by Duckweed (Lemna minor) in Broiler Diet

    OpenAIRE

    M. U. Ahammad; M.S.R. Swapon; Yeasmin, T.; Rahman, M.S.; Ali, M. S.

    2003-01-01

    An experiment was conducted with 120, seven-day old Vencobb commercial broiler chick feeding ad libitum upto 42 days of age on 4 different iso-nitrogenous and iso-energetic diet formulated by replacing dietary sesame oil cake (SOC) by duckweed (DW) to have its effect on performance of broilers. Live weight, feed conversion and profitability increased when sesame oil cake was partially replaced by duck weed. Complete SOC replaced diet significantly reduced live weight gain, feed intake, feed c...

  16. Are Radishes Really Allelopathic to Lettuce?

    Science.gov (United States)

    Santaniello, Catherine M.; Koning, Ross E.

    1996-01-01

    Presents an experiment that challenges the claim that sprouting radish seedlings release chemicals into the environment that inhibit germination of lettuce seeds. Reports that although no simple allelopathic demonstration was observed, the experiment provides fertile ground for further experimentation in inquiry-based laboratory experiences. (JRH)

  17. 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…

  18. Evaluation of performance of full-scale duckweed and algal ponds receiving septage.

    Science.gov (United States)

    Papadopoulos, Frantzis H; Metaxa, Eirini G; Iatrou, Miltos N; Papadopoulos, Aristotelis H

    2014-12-01

    The performance of duckweed and algal systems in removing fecal bacteria, organic matter, and nutrients was evaluated in three full-scale ponds operating in series. Trucks collected septage from holding tanks and discharged it into the system, daily. The inflow rates varied between the warm and the cold season. Duckweed and algae naturally colonized the ponds in two successive periods of 10 and 13 months, respectively. Environmental conditions were determined at various pond depths. Without harvesting, the duckweed system was neutral and anoxic. Alkaline and oversaturation conditions were observed in the algal system. The overall removals of 5-day biochemical oxygen demand, total suspended solids, total nitrogen removal, and orthophosphate (ortho-PO4(3-)) ranged from 94 to 97, 62 to 84, 68 to 74, and 0 to 26%, respectively. The E. coli and enterococci reductions varied between 2.2 to 3.0 and 1.1 to 1.4 log units, respectively. The upper values were always associated with the algal system. PMID:25654933

  19. Improving Production of Bioethanol from Duckweed (Landoltia punctata by Pectinase Pretreatment

    Directory of Open Access Journals (Sweden)

    Qian Chen

    2012-08-01

    Full Text Available Landoltia punctata, a widely distributed duckweed strain with the ability to accumulate starch, was used as a novel feedstock for bioethanol production by Saccharomyces cerevisiae. To improve ethanol production, pectinase pretreatment was used to release much more glucose from L. punctata mash and the pretreatment conditions (enzyme loading, temperature and pretreatment time for the duckweed were optimized by using a surface response design. The results showed that maximum glucose yield was 218.64 ± 3.10 mg/g dry matter, which is a 142% increase compared to the untreated mash, with a pectinase dose of 26.54 pectin transeliminase unit/g mash at 45 °C for 300 min. Pectinase pretreatment apparently changed the ultrastructure of L. punctata, as evidenced by scanning electron microscopy analysis. Further fermentation experiments were performed and 30.8 ± 0.8 g/L of ethanol concentration, 90.04% of fermentation efficiency and 2.20 g/L/h of productivity rate were achieved. This is the highest ethanol concentration reported to date using duckweed as the feedstock.

  20. Contamination of lettuce with antibiotic resistant E. coli after slurry application

    DEFF Research Database (Denmark)

    Jensen, Annette Nygaard; Storm, Christina

    2011-01-01

    Due to disease outbreaks associated with contaminated vegetables it has been speculated to what extent this may be linked with application of animal manure as fertilizer, which is particularly practiced in organic vegetable production where conventional fertilizers are prohibited. A field survey was therefore performed to assess the survival and transfer of antibiotic-resistant E. coli from animal manure to lettuces, with E. coli serving as an indicator of bacterial enteric pathogens. Animal slurry was applied to 3 Danish fields prior to planting of lettuce seedlings, then 5-8 weeks later at the normal time of harvest, inner and outer leafs of 10 lettuce heads were pooled into one sample unit with a total of 50 pools per field. Additionally, in one field, 15 soil samples were collected weekly until the harvest time. E. coli was enumerated by plating 1 mL of 10-fold serial dilutions of 5 g of homogenized sample material, i.e. manure, soil and lettuce onto PetrifilmTM Select E. coli count plates (3M) containing16 mg/L streptomycin or 16 mg/L ampicilin or no antibiotics. Plates were then incubated 24 h at 44°C. Selected isolates of E. coli (n=83) from slurry, soil and lettuce were analysed by PFGE DNA typing for further discrimination. The slurry applied to the fields contained 3.0-4.5 Log10 E. coli CFU/g and resistant E. coli ranged from 1.0 to 4.4 Log10 E. coli CFU/g with particular high numbers of streptomycin resistant E. coli in conventional pig slurry (field 1) opposed to organic cow slurry (field 2 and 3). E. coli was found in 36-54% of the pooled lettuce samples at the three fields with a detection limit of 10 CFU/g and 10-18% and 0-2% of pools had streptomycin and ampicilin resistant E. coli, respectively. Unexpectedly, the highest percentage of lettuce pools with antibiotic resistant E. coli were found on fields fertilized with organic cow slurry where 0.1-5% of E. coli was resistant opposed to 5-50% resistant E. coli in conventional slurry. Numbers of E. coli in 14-20% of pooled lettuce samples exceeded a satisfactory microbiological hygiene criteria level of 100 CFU/g. The numbers of resistant E. coli for both antibiotics were approximately 10-fold lower than the sensitive E. coli. At the time of harvest, the numbers of E. coli in 5 of 15 soil samples were reduced below the detection limit and no samples exceeded 100 CFU/g, which was in contrast to the lettuce samples, where 20% of faecally contaminated samples contained >100 E. coli/g. This indicates that fecal contamination of crops originated from alternative sources such as contaminated water or wildlife. This was supported by genotyping of E. coli, where half of the 21 PFGE types were found on single occasions in either soil or lettuce, whereas the other half was found both in slurry and lettuce indicating a possible transfer.

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

    International Nuclear Information System (INIS)

    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 137Cs irradiator using MCNP. The simulated 137Cs 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/cm3) and high density (rib) region (0.86 g/cm3). 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)

  2. Feline Calicivirus, Murine Norovirus, Porcine Sapovirus, and Tulane Virus Survival on Postharvest Lettuce.

    Science.gov (United States)

    Esseili, Malak A; Saif, Linda J; Farkas, Tibor; Wang, Qiuhong

    2015-08-01

    Human norovirus (HuNoV) is the leading cause of foodborne illnesses, with an increasing number of outbreaks associated with leafy greens. Because HuNoV cannot be routinely cultured, culturable feline calicivirus (FCV), murine norovirus (MNV), porcine sapovirus (SaV), and Tulane virus (TV) have been used as surrogates. These viruses are generated in different cell lines as infected cell lysates, which may differentially affect their stability. Our objective was to uniformly compare the survival of these viruses on postharvest lettuce while evaluating the effects of cell lysates on their survival. Viruses were semipurified from cell lysates by ultrafiltration or ultracentrifugation followed by resuspension in sterile water. Virus survival was examined before and after semipurification: in suspension at room temperature (RT) until day 28 and on lettuce leaves stored at RT for 3 days or at 4°C for 7 and 14 days. In suspension, both methods significantly enhanced the survival of all viruses. On lettuce, the survival of MNV in cell lysates was similar to that in water, under all storage conditions. In contrast, the survival of FCV, SaV, and TV was differentially enhanced, under different storage conditions, by removing cell lysates. Following semipurification, viruses showed similar persistence to each other on lettuce stored under all conditions, with the exception of ultracentrifugation-purified FCV, which showed a higher inactivation rate than MNV at 4°C for 14 days. In conclusion, the presence of cell lysates in viral suspensions underestimated the survivability of these surrogate viruses, while viral semipurification revealed similar survivabilities on postharvest lettuce leaves. PMID:26002891

  3. Engineering Corynebacterium crenatum to produce higher alcohols for biofuel using hydrolysates of duckweed (Landoltia punctata) as feedstock.

    Science.gov (United States)

    Su, Haifeng; Jiang, Juan; Lu, Qiuli; Zhao, Zhao; Xie, Tian; Zhao, Hai; Wang, Maolin

    2015-01-01

    Early trials have demonstrated great potential for the use of duckweed (family Lemnaceae) as the next generation of energy plants for the production of biofuels. Achieving this technological advance demands research to develop novel bioengineering microorganisms that can ferment duckweed feedstock to produce higher alcohols. In this study, we used relevant genes to transfer five metabolic pathways of isoleucine, leucine and valine from the yeast Saccharomyces cerevisiae into the bioengineered microorganism Corynebacterium crenatum. Experimental results showed that the bioengineered strain was able to produce 1026.61 mg/L of 2-methyl-1-butanol by fermenting glucose, compared to 981.79 mg/L from the acid hydrolysates of duckweed. The highest isobutanol yields achieved were 1264.63 mg/L from glucose and 1154.83 mg/L from duckweed, and the corresponding highest yields of 3-methyl-1-butanol were 748.35 and 684.79 mg/L. Our findings demonstrate the feasibility of using bioengineered C. crenatum as a platform to construct a bacterial strain that is capable of producing higher alcohols. We have also shown the promise of using duckweed as the basis for developing higher alcohols, illustrating that this group of plants represents an ideal fermentation substrate that can be considered the next generation of alternative energy feedstocks. PMID:25889648

  4. The influence of barley straw extract addition on the growth of duckweed (Lemna valdiviana Phil. under laboratory conditions

    Directory of Open Access Journals (Sweden)

    P?czu?a W.

    2014-01-01

    Full Text Available Due to its ability to forming dense mats in small waterbodies, duckweeds are often considered as nuisance plants in some freshwaters. Up to now, few techniques had been tested aiming towards managing duckweeds, but all of them had appeared to have some disadvantages. As an attempt to find a new effective management tool, a laboratory experiment assessing the influence of barley straw (BS extract addition – a substance used in algal bloom control, upon the growth of the duckweed Lemna valdiviana, was performed. Reaction on two various concentrations of BS extract were quantified by measurements of changes in duckweed biomass and root length. The results showed that plants which have received the extract increased their biomass slower than that of the control, however only those with the addition of smaller amounts of BS differed significantly from the controls. Furthermore, BS addition stimulated the root growth in both experimental tanks. This implies that the mean roots length was higher, although the statistical differences were insignificant. As possible explanation for the observed changes we suggest that: (1 the growth inhibition of Lemna valvidiana under exposition to BS extract might be induced by an uptake of organic compounds from which some (phenolic substances are (probably toxic; (2 competitive interactions with the microbial communities developed upon the duckweed roots might play a role as well.

  5. Deposição de calda de pulverização sobre plantas de salvínia em função de pontas de pulverização e arranjos populacionais entre plantas de Aguapé e Alface-D'Água / Spray deposition on water fern plants in function of nozzle tips and population arrangements with water Hyacinth and Water Lettuce plants

    Scientific Electronic Library Online (English)

    S.R., Marchi; D., Martins; N.V., Costa; C.A., Carbonari; J.R.V., Silva.

    2011-03-01

    Full Text Available Este trabalho teve como objetivo avaliar o depósito de calda pulverizada por dois tipos de pontas de pulverização sobre plantas de Salvinia auriculata dispostas em diferentes arranjos populacionais com plantas de Eichhornia crassipes e Pistia stratiotes. Um experimento foi conduzido em condições de [...] caixas-d'água em delineamento inteiramente casualizado, com quatro repetições. Os tratamentos foram dispostos em esquema fatorial 2 x 8, sendo dois tipos de pontas de pulverização (ConeJet TXVK-8 e TeeJet DG 11002 VS) e oito proporções entre as plantas aquáticas, a saber: dominância total da área de cobertura da caixa-d'água pelas plantas de salvínia (100%); e as proporções entre plantas de salvínia e de aguapé ou alface-d'água a 75%:25%, 50%:50% e 25%:75%. Também foi utilizada uma densidade tripla, na qual as três espécies estiveram igualmente dispostas na proporção de 33%. Soluções dos corantes Amarelo Tartrasina FDC-5 a 3.500 ppm e Azul Brilhante FDC-1 a 1.000 ppm foram utilizadas como traçadores para as pontas TXVK-8 e DG 11002VS, respectivamente. A pulverização das soluções foi efetuada na mesma unidade experimental, com intervalo de 30 minutos entre si, com auxílio de um pulverizador costal pressurizado com CO2, calibrado de modo que proporcionasse volume de aplicação aproximado de 200 L ha-1. Não foram observadas diferenças estatísticas entre os tipos de pontas de pulverização nas diferentes proporções estudadas, exceto para depósitos totais de calda de pulverização nas plantas na condição de dominância total da salvínia, uma vez que a ponta ConeJet TXVK-8 foi superior à TeeJet DG 11002 VS. Os valores dos depósitos diminuíram com o aumento da proporção de plantas de aguapé na associação e foram na condição em que 25% de plantas de salvínia estiveram associadas a 75% de plantas de aguapé. A presença da espécie alface-d'água não influenciou a deposição de gotas sobre as folhas de salvínia. Abstract in english This study aimed to evaluate two types of spray tips (ConeJet TXVK-8 and TeeJet DG 11002 VS) and the amount of spray mix deposited on Salvinia auriculata plants organized under different population arrangements with Eichhornia crassipes and Pistia stratiotes plants. In addition to a full-dominance p [...] roportion over the area, corresponding to 100% cover of the water tank by eared water moss plants, arrangements with either water hyacinth or water lettuce were made at 75%:25%, 50%:50%, and 25%:75%. A triple density, in which the three species were equally disposed at a 33.33% proportion, was also used. Dye solutions of FD&C Yellow no. 5 at 3,500 ppm and FD&C Blue no.1 at 1,000 ppm were used, as spraying tracers for TXVK-8 and DG 11002 VS nozzles, respectively. Both solutions were sprayed at the same plot within a 30-minute interval each, through a CO2 pressured backpack, calibrated to deliver a spray volume of around 200 L ha-1. The total spray deposits were estimated in mL per plant and the unit deposits in mL cm² of foliar surface. No significant differences were observed between the nozzle tips used at different population arrangements, except total spray mix deposited on plants at 100% of eared water moss dominance proportion, with ConeJet TXVK-8, providing superior spray mix deposition, compared with TeeJet DG 11002 VS. The highest spray mix deposition was obtained under 100% of salvínia dominance. However, the spray mix quantity decreased with increase of water hyacinth in the proportion and reached the lowest value when 25% of eared water moss plants were associated with 75% of water hyacinth plants. The presence of water lettuce did not influence spray mix deposition over eared water moss plants.

  6. Lettuce seed germination and root elongation toxicity evaluation of the F-Area seepline soils

    International Nuclear Information System (INIS)

    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

  7. 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 consórcio. Quanto mais atrasado o transplante da alface menor foi a sua produtividade. Houve efeito de época de cultivo sobre a dimensão da vantagem agronômica do consórcio sobre a monocultura. Na primeira época de cultivo, os consórcios estabelecidos com o transplante da alface de 30 dias antes e até 20 dias após o transplante do tomate proporcionaram índices de eficiência do uso da área (EUA de 1,63 a 2,22. Na segunda época, os consórcios estabelecidos com o transplante da alface antes do tomate, em até 30 dias, proporcionaram índices EUA de 1,57 a 2,05.

  8. Agricultural and Management Practices and Bacterial Contamination in Greenhouse versus Open Field Lettuce Production

    Directory of Open Access Journals (Sweden)

    Kevin Holvoet

    2014-12-01

    Full Text Available 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.

  9. 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

    2015-01-01

    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

  10. 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 evaluated as mycorrhizal parameters. The results showed a different response to mycorrhization of the four lettuce Cvs. In general, mycorrhized lettuce plants had a better response to lower level of nitrogen and phosphorus sources.

  11. Internal distribution of Cd in lettuce and resulting effects on Cd trophic transfer to the snail: Achatina fulica.

    Science.gov (United States)

    Li, Cheng-Cheng; Dang, Fei; Cang, Long; Zhou, Dong-Mei; Peijnenburg, Willie J G M

    2015-09-01

    The mechanisms underlying Cd trophic transfer along the soil-lettuce-snail food chain were investigated. The fate of Cd within cells, revealed by assessment of Cd chemical forms and of subcellular partitioning, differed between the two examined lettuce species that we examined (L. longifolia and L. crispa). The species-specific internal Cd fate not only influenced Cd burdens in lettuce, with higher Cd levels in L. crispa, but also affected Cd transfer efficiency to the consumer snail (Achatina fulica). Especially, the incorporation of Cd chemical forms (Cd in the inorganic, water-soluble and pectates and protein-integrated forms) in lettuce could best explain Cd trophic transfer, when compared to dietary Cd levels alone and/or subcellular Cd partitioning. Trophically available metal on the subcellular partitioning base failed to shed light on Cd transfer in this study. After 28-d of exposure, most Cd was trapped in the viscera of Achatina fulica, and cadmium bio-magnification was noted in the snails, as the transfer factor of lettuce-to-snail soft tissue was larger than one. This study provides a first step to apply a chemical speciation approach to dictate the trophic bioavailability of Cd through the soil-plant-snail system, which might be an important pre-requisite for mechanistic understanding of metal trophic transfer. PMID:25930053

  12. Unravelling the resistance mechanism of lettuce against Nasonovia ribisnigri

    OpenAIRE

    Broeke, C.J.M., ten

    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. Ho...

  13. Quantitative proteomic analysis of the Salmonella-lettuce interaction

    OpenAIRE

    Yuping ZHANG; Nandakumar, Renu; Bartelt-Hunt, Shannon L.; Snow, Daniel D.; Hodges, Laurie; Li, Xu

    2014-01-01

    Human pathogens can internalize food crops through root and surface uptake and persist inside crop plants. The goal of the study was to elucidate the global modulation of bacteria and plant protein expression after Salmonella internalizes lettuce. A quantitative proteomic approach was used to analyse the protein expression of Salmonella enterica serovar Infantis and lettuce cultivar Green Salad Bowl 24 h after infiltrating S. Infantis into lettuce leaves. Among the 50 differentially expressed...

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

    OpenAIRE

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

    2012-01-01

    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 virulentus spores in a nutrient film technique (NFT) system. Lettuce plants showing BVD are generally infected by two viruses: Mirafiori lettuce big-vein virus (MiLBVV, genus Ophiovirus) and LBVaV....

  15. Effect of abscisic acid on biochemical constituents, enzymatic and non enzymatic antioxidant status of lettuce (Lactuca sativa L. under varied irrigation regimes

    Directory of Open Access Journals (Sweden)

    Mohamed A. Al Muhairi

    2015-12-01

    Full Text Available Economically important vegetable crop lettuce (Lactuca sativa L. of family Asteraceae was selected for the present investigation. It is being cultivated in UAE due to its commercial importance. In lettuce cultivation, the major problem is the requirement of large quantities of irrigation water. The present study was aimed to reduce the water consumption of lettuce cultivation; for that, a varied irrigation regime was used with the application of abscisic acid (ABA. The parameters studied were biochemical constituents, antioxidant potential and antioxidant enzymes’ activities in lettuce plants under drought stress and its response to ABA under stress. Drought stress caused an increase in the biochemical constituents like proline and amino acid contents when compared with control and also increased under individual ABA treatments and treatments under drought stress. The non-enzymatic antioxidant molecules like ascorbate and ?-tocopherol showed significant increase under drought condition in lettuce. ABA slightly reduced these contents. The antioxidant enzymes like superoxide dismutase, catalase and peroxidase showed significant increase under drought condition and ABA caused significant enhancement in these antioxidant enzymes under drought stress and also in unstressed conditions, thereby protecting the plants from the deleterious effects of drought stress. From the results of this investigation, it can be concluded that ABA in 10 mg g?1 can be used as a potential tool to minimise the drought stress effects in lettuce cultivation.

  16. 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 lettuces and their modifications are also discussed in the paper. It is possible to obtain 'nitrate-free' lettuces in an economically feasible way. PMID:25345876

  17. Green remediation of tetracyclines in soil-water systems

    OpenAIRE

    Om Prakash Bansal

    2013-01-01

    The presence of tetracyclines in soil and surface water is an emerging concern. The present study was undertaken to investigate remediation of tetracylines (tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC)) from aqueous solution using vetiver grass, water lettuce, and sunflower and root exudates of water lettuce, sunflower and from soil by tomato, Indian mustard and carrot plant. The data of this study denote that vetiver grass, water lettuce, sunflower remedy tetracy...

  18. Utilization of Duckweed (Lemna paucicostata in Least-cost Feed Formulation for Broiler Starter: A Linear Programming Analysis

    Directory of Open Access Journals (Sweden)

    T.O.S. Olorunfemi

    2006-01-01

    Full Text Available This study was on the economic use of locally available and non-conventional feedstuff - Duckweed (Lemna paucicostata as dietary component of feed for broilers aged between 0 and 5 weeks old using Linear Programming (LP technique to investigate, analyse and determine the most efficient way of compounding the least-cost ration. Mathematical models were constructed, taking into consideration nutrient composition of each of the available ingredient, raw material specifications, costs and nutrient requirements of the broiler starter`s mash. Simplex algorithm was used in solving the resulting linear programming models. The LP model gave least cost feed formulation containing duckweed as optimum at iteration 26. The result shows that utilization of diet containing 26.09% of duckweed is cost-effective by reducing the cost of the feed by 10.64% and this will invariably improve profitability in broiler production.

  19. Transient Protein Expression by Agroinfiltration in Lettuce.

    Science.gov (United States)

    Chen, Qiang; Dent, Matthew; Hurtado, Jonathan; Stahnke, Jake; McNulty, Alyssa; Leuzinger, Kahlin; Lai, Huafang

    2016-01-01

    Current systems of recombinant protein production include bacterial, insect, and mammalian cell culture. However, these platforms are expensive to build and operate at commercial scales and/or have limited abilities to produce complex proteins. In recent years, plant-based expression systems have become top candidates for the production of recombinant proteins as they are highly scalable, robust, safe, and can produce complex proteins due to having a eukaryotic endomembrane system. Newly developed "deconstructed" viral vectors delivered via Agrobacterium tumefaciens (agroinfiltration) have enabled robust plant-based production of proteins with a wide range of applications. The leafy Lactuca sativa (lettuce) plant with its strong foundation in agriculture is an excellent host for pharmaceutical protein production. Here, we describe a method for agroinfiltration of lettuce that can rapidly produce high levels of recombinant proteins in a matter of days and has the potential to be scaled up to an agricultural level. PMID:26614281

  20. Use of Duckweed, Lemna minor, as a Protein Feedstuff in Practical Diets for Common Carp, Cyprinus carpio, Fry

    OpenAIRE

    Erdal Y?lmaz; AKYURT, ?hsan; Günal, Gökhan

    2004-01-01

    The use of dried duckweed, Lemna minor, as a dietary protein source for Cyprinus carpio common carp fry reared in baskets was the topic of investigation in this study. Five diets with similar E:P ratios were fed to common carp fry with an average initial weight of 0.29 g for 90 days. A diet containing 5%, 10%, 15%, or 20% duckweed was substituted for the commercial 32% protein control-group diet, fed in normal rations to common carp. There was no significant difference between the growth perf...

  1. Effects of compost tea treatments on productivity of lettuce and kohlrabi systems under organic cropping management

    OpenAIRE

    Catello Pane; Assunta Maria Palese; Giuseppe Celano; Massimo Zaccardelli

    2014-01-01

    The use of compost tea (CT) is becoming interesting for applications in organic agriculture. CTs are oxygenated extracts of compost that give positive effects on the crops because contain bioactive molecules and microorganisms that improve plant growth and health. This study was carried out to evaluate the effects of CTs applied as foliar spray and drenching, respectively, on kohlrabi and lettuce cultivation. The CT tested here was originated by an aerated water-extraction of two artichoke an...

  2. Impact of biosolids and wastewater effluent application to agricultural land on steroidal hormone content in lettuce plants.

    Science.gov (United States)

    Shargil, Dorit; Gerstl, Zev; Fine, Pinchas; Nitsan, Ido; Kurtzman, Daniel

    2015-02-01

    One of the major concerns for human health in the past decade is the potential dangers posed by increased concentrations of steroidal hormones in soils and water. These hormones are considered to be endocrine disrupting compounds (EDCs), which may harm human health when exposed to high concentrations, or in the case of long term exposure to lower concentrations. In a 3 year study, two steroids, estrone and testosterone, were measured in lettuce plants irrigated with wastewater effluents and freshwater and treated with several types of biosolids. The relative contribution of the different factors, mainly irrigation water and biosolids, to the hormone levels in the lettuce plants was determined. It was found that irrigation water, which contained significant amounts of hormones, had the most substantial effect, whereas biosolids had only minor influence on hormone levels in the lettuce. The hormone levels in the plants were compared to the FDA recommendation for daily consumption in food, and were found to exceed the recommended level (when consumed by a typical individual), and therefore could have negative physiological impacts. Overall this study shows that biosolids have little effect on hormone uptake by lettuce, and it emphasizes the negative impact of irrigation water on these levels, which is of concern to public health. PMID:25461037

  3. Evaluación de la biomasa y manejo de Lemna gibba (lenteja de agua) en la bahía interior del Lago Titicaca, Puno / Evaluation of biomass and management Lemna gibba (duckweed) in the inner bay of Lake Titicaca, Puno

    Scientific Electronic Library Online (English)

    Ángel, Canales-Gutiérrez.

    2010-07-01

    Full Text Available Uno de los mayores problemas que enfrenta la ciudad de Puno es la presencia de la lenteja de agua (Lemna gibba) en la bahía interior del Lago Titicaca, debido al proceso de eutrofización que sufre a causa del mal tratamiento de las aguas residuales de la ciudad de Puno. Muchas de las estrategias pla [...] nteadas hasta ahora no han dado resultados positivos en la reducción de la biomasa de Lemna gibba, debido a que estos planes están direccionados a la exterminación de este organismo. En lugar de ello se debe pensar en la forma más sostenible de hacer uso de la lenteja. Es por eso que los objetivos fueron: (a) estimar la biomasa (kg/m²) de lenteja de agua de la bahía interior del lago Titicaca y, (b) plantear una estrategia de manejo de la lenteja de agua de la bahía interior del lago Titicaca. El promedio de la biomasa de la lenteja de agua en la bahía interior fue de 6.94 kg/m², mientras que los promedios de pH y temperatura del agua fueron de 6.3 y 13.8°C, respectivamente. Esto prueba la eficacia de este organismo para crecer en condiciones difíciles (además hay altos niveles de N, P y metales pesados), por lo que su manejo puede ser una alternativa para disminuir el proceso de eutrofización del lago. Las estrategias de manejo de lenteja estuvieron enmarcadas dentro de un plano social, económico y ambiental, lo que permite su sostenibilidad en beneficio de la población de Puno y del ecosistema del lago Titicaca. Abstract in english One of the biggest problems Puno city is currently facing is the presence of duckweed (Lemna gibba) in the inner bay of Lake Titicaca, caused by eutrophication due to bad wastewater treatment. Many of the strategies proposed so far have not yielded positive results, because these plans were directed [...] to the extermination of this organism. Instead, the most sustainable duckweed use should be considered. That is why the objectives of this study were: (a) To estimate duckweed biomass (kg/m²) in the inner bay of Lake Titicaca, (b) To propose a management strategy for the duckweed from the inner bay of Lake Titicaca. The average biomass of the duckweed in the inner bay was 6.94 kg/m²; the average pH and temperature of the water were 6.3 and 13.8°C, respectively. This proves the effectiveness of this organism to grow in difficult conditions (in addition there are high levels of N, P and heavy metals), so that its management can be used as an alternative to reduce the eutrophication of the lake. Moreover, duckweed management strategies were framed within social, economical and environmental plans. Therefore, this macrophyte management is sustainable and beneficial for the people of Puno and the ecosystem of Lake Titicaca.

  4. Duckweed (Lemna paucicostata Heglem ex Engle) in the diet of tilapia (Sarotherodon galilaeus)

    OpenAIRE

    Okoye, F.C.; Mbagwu, I.G.

    1985-01-01

    The growth of Sarotherodon galilaeus fingerlings fed with test diet of 33% crude protein and containing 10% duckweed was compared with standard KLRI/40/6 feed of 40% crude protein. From an initial mean weight of 1.18gm and 1.17gm, the fingerlings in the test diet and control respectively grew to a final mean weight of 2.17gm and 1.98gm after seven weeks. With mean growth rate of 2.02% and 1.65% of their body weight per day respectively for the test diet and the control, it was obvious that th...

  5. Apparent digestibility coefficient of duckweed (Lemna minor), fresh and dry for Nile tilapia (Oreochromis niloticus L.)

    OpenAIRE

    El-Shafai, S.A.A.M.; el-Gohary, F.; Verreth, J.A.J.; Schrama, J.W.; Gijzen, H.J.

    2004-01-01

    Dry matter (DMD), protein (PD), ash (AD), fat (FD), gross energy (ED) and phosphorus (PhD) digestibility coefficients were determined for five different iso-N fish diets fed to Nile tilapia (Oreochromis niloticus). The control diet contained fishmeal (35Œ corn (29Œ wheat (20Œ wheat bran (10Œ fish oil (3Œ diamol (2€and premix (1Ž Partial replacement of dry matter of fishmeal, corn grain, wheat grain, wheat bran and fish oil by 20nd 40?f dry matter of duckweed, in a dry and fresh form, was perf...

  6. Effects of osmotic stress on antioxidative system of duckweed (Lemna minor L)

    OpenAIRE

    RADI?, SANDRA; Pevalek-Kozlina, Branka

    2010-01-01

    Background and Purpose: It is known that osmotic stress may cause damage to cells by inducing active oxygen species production or by disrupting detoxification mechanisms. We hypothesize that increased activity of antioxidant enzymes in duckweed (Lemna minor L.) provides a mechanism of tolerance to osmotic stress. Material and Methods: Plants were subjected to NaCl- (50 mM), mannitol- (50 and 100 mM) and polyethylene glycol-mediated osmotic stress (PEG, 50 mM) for a period of 15 d...

  7. Feeding Diets Containing Different Forms of Duckweed on Productive Performance and Egg Quality of Ducks

    OpenAIRE

    B. Indarsih; M. H. Tamsil

    2012-01-01

    The present experiment was undertaken to study the feeding effect of diets containing different forms of duckweed for local ducks on their productive performance and egg quality or egg yolk pigmentation. A total of 90 birds of 24 wk old ducks were randomly divided into 18 experimental units of 2.0 x 1.0 m2 of cages. The experiment was assigned in a completely randomized design (3 treatments with 6 replicates, 5 birds each). There were 3 dietary treatments, namely P1= ducks fed a complete die...

  8. Alternative sanitization methods for minimally processed lettuce in comparison to sodium hypochlorite

    Scientific Electronic Library Online (English)

    Mara Lígia Biazotto, Bachelli; Rívia Darla Álvares, Amaral; Benedito Carlos, Benedetti.

    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 trihalomethane [...] s 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.

  9. 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 ?m. 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. PMID:24516433

  10. 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...

  11. 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...

  12. 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...

  13. 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. PMID:25719871

  14. Egg parasitoids of Edessa meditabunda (Fabricius (Pentatomidae in lettuce crop

    Directory of Open Access Journals (Sweden)

    Bruna M. Favetti

    2013-06-01

    Full Text Available Egg parasitoids of Edessa meditabunda (Fabricius (Pentatomidae in lettuce crop. This study evaluated the occurrence of parasitoids in eggs of the stink bug, Edessa meditabunda (Fabricius, 1794 (Heteroptera, Pentatomidae found on lettuce crop in Mato Grosso State, Brazil. Samples were collected in the vegetable garden "Cheiro Verde", in the municipality of Tangará da Serra, in curly lettuce. A bed of lettuce was selected randomly, where the eggs of E. meditabunda were collected. Five-hundred and seventy eight eggs of E. meditabunda were collected, 86.3% of them parasitized by Telenomus podisi Ashmead, 1893 (Hymenoptera, Platygastridae, Trissolcus urichi Crawford, 1913 (Hymenoptera, Platygastridae and Neorileya albipes Girault, 1913 (Hymenoptera, Eurytomidae, representing respectively 57.0%, 38.2% and 4.8% of the emerged individuals. This is the first record of these three species parasitizing eggs of E. meditabunda in lettuce.

  15. RELEASE OF CRISPHEAD LETTUCE GERMPLASM WITH RESISTANCES TO CORKY ROOT AND LETTUCE MOSAIC

    Science.gov (United States)

    The Agricultural Research Service, United States Department of Agriculture announces the release of seven breeding lines of crisphead lettuce (Lactuca sativa L.). The lines 04-0344, 04-0350, 04-0353, 04-0363, 04-0368, 04-0375, and 04-0379 have dull, medium-dark-green outer leaves, similar to 'Salina...

  16. Effect of nitrogen nutrition on growth and nitrate accumulation in lettuce (Lactuca sativa L.), under various conditions of radiation and temperature

    International Nuclear Information System (INIS)

    A better understanding of the effect of environmental factors on growth and nitrate accumulation in plants is necessary to develop cultivation practices, and in particular for providing lettuces with a low nitrate content. This study was conducted to analyse the effect of nitrogen supply on the interception and conversion of the PAR in dry matter, and on the nitrate and water accumulations in fresh tissues of the lettuce, for various conditions of temperature and radiation. The growth, and water and nitrate concentrations of two soilless cultures of lettuce (summer and autumn) were measured for two levels of radiation and two levels of nitrogen supply. RUE ranged from 2.12 to 3.50 gMJ-1, being higher for a low radiation level and for a high nitrogen supply. There was a positive correlation between the lettuce nitrate and water contents. The slope of this relationship was not affected by environmental conditions, indicating a strong interdependance between nitrate and water accumulation in lettuce. (author)

  17. Effects of compost tea treatments on productivity of lettuce and kohlrabi systems under organic cropping management

    Directory of Open Access Journals (Sweden)

    Catello Pane

    2014-09-01

    Full Text Available The use of compost tea (CT is becoming interesting for applications in organic agriculture. CTs are oxygenated extracts of compost that give positive effects on the crops because contain bioactive molecules and microorganisms that improve plant growth and health. This study was carried out to evaluate the effects of CTs applied as foliar spray and drenching, respectively, on kohlrabi and lettuce cultivation. The CT tested here was originated by an aerated water-extraction of two artichoke and fennel composts. CT treatments considerably improved crop yields. CT, in fact, increased lettuce and kohlrabi commercial yields higher 24% and 32%, respectively. Due to CT, the physiological and nutritional status of the plants increased, as noticed by foliar chlorophyll content assessment measured during crop cycles. The results provided encouraging indications about the practical application of CT in horticultural organic farming system.

  18. Identification of lettuce genes differentially expressed in a Verticillium dahliae-lettuce interaction by suppression subtractive hybridization

    Science.gov (United States)

    Verticillium wilt, caused by the fungus Verticillium dahliae, is an emerging threat to the U.S. lettuce industry. Lettuce germplasm with resistance to race 1of V. dahliae is available for breeding programs, although germplasm with resistance to race 2 of the pathogen has not been identified. The obj...

  19. MU06-857, a Green Leaf Lettuce Breeding Line with Resistance to Leafminer and Lettuce Mosaic Virus.

    Science.gov (United States)

    The Agricultural Research Service, United States Department of Agriculture announces the release of a breeding line of green leaf lettuce (Lactuca sativa L.) with resistance to leafminers (Liriomyza langei Frick) and lettuce mosaic. The line MU06-857 is similar to cultivar ‘Lolla Rossa’ (‘Lollo Ros...

  20. 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.

  1. Sanitation and design of lettuce coring knives for minimizing Escherichia coli O157:H7 contamination.

    Science.gov (United States)

    Zhou, Bin; Luo, Yaguang; Millner, Patricia; Feng, Hao

    2012-03-01

    This study was undertaken to examine the effect of ultrasound in combination with chlorine on the reduction of Escherichia coli O157:H7 populations on lettuce coring knives. Two new coring devices designed to mitigate pathogen attachment were fabricated and evaluated. The coring rings of the knives were dip inoculated with soil slurry containing 10? E. coli cells and treated with chlorinated water with and without ultrasonication for 30, 60, and 120 s. The rough welding joints on currently used in-field lettuce coring knives provided a site conducive to bacterial attachment and resistant to cell removal during sanitation treatment. The two modified coring knives harbored significantly fewer E. coli cells than did the currently used commercial model, and the efficacy of the disinfection treatment was high (P welding joint within 30 s in 1 ppm of chlorinated water. The redesigned coring knives and an ultrasound plus chlorine combination treatment may provide practical options for minimizing the microbial safety hazards of lettuce processed by core-in-field operations. PMID:22410232

  2. A NEW APPROACH FOR CULTURING LEMNA MINOR (DUCKWEED) AND STANDARDIZED METHOD FOR USING ATRAZINE AS A REFERENCE TOXICANT

    Science.gov (United States)

    Lemna minor (Duckweed) is commonly used in aquatic toxicity investigations. Methods for culturing and testing with reference toxicants, such as atrazine, are somewhat variable among researchers. Our goal was to develop standardized methods of culturing and testing for use with L....

  3. Draft Genome Sequence of Acinetobacter calcoaceticus Strain P23, a Plant Growth-Promoting Bacterium of Duckweed.

    Science.gov (United States)

    Sugawara, Masayuki; Hosoyama, Akira; Yamazoe, Atsushi; Morikawa, Masaaki

    2015-01-01

    Acinetobacter calcoaceticus strain P23 is a plant growth-promoting bacterium, which was isolated from the surface of duckweed. We report here the draft genome sequence of strain P23. The genome data will serve as a valuable reference for understanding the molecular mechanism of plant growth promotion in aquatic plants. PMID:25720680

  4. Draft Genome Sequence of Acinetobacter calcoaceticus Strain P23, a Plant Growth-Promoting Bacterium of Duckweed

    OpenAIRE

    Sugawara, Masayuki; Hosoyama, Akira; Yamazoe, Atsushi; Morikawa, Masaaki

    2015-01-01

    Acinetobacter calcoaceticus strain P23 is a plant growth-promoting bacterium, which was isolated from the surface of duckweed. We report here the draft genome sequence of strain P23. The genome data will serve as a valuable reference for understanding the molecular mechanism of plant growth promotion in aquatic plants.

  5. 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 of Fafard #2 being much more red and those in 100% arcillite almost completely green. The red-leaf cultivar 'Outredgeous' showed increasing chlorophyll (SPAD values) with increasing percentage of arcillite. In all cultivars tested it appears that a mixture of media types, usually 50:50 or 30:70 Fafard #2: arcillite, sustained healthier, more productive plants. Smaller, less productive plants in either of the individual media may indicate stress issues, however more work is needed to understand the reasons for this sub-optimal growth. This work was supported by NASA

  6. 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 operators with a minimum of training, and supported excellent lettuce growth for the duration of the 14-day test. The operational DRAT field testing in the HDU identified light quality issues related to morphology and pigment development that will need to be addressed through additional testing. Feedback from the crew, ground support personnel, and human factors leads was uniformly positive on the psychological value of having the crop production system in the pressurized excursion module. Data are being used to design a plant atrium with LED lighting to evaluate salad crop growth during NASA's 2011 DRATS test.

  7. BIOSORPTIVE REMOVAL OF HEAVY METALS FROM WASTEWATER USING DUCKWEED

    OpenAIRE

    Ankita Suhag; Richa Gupta,; Archana Tiwari

    2011-01-01

    Water pollution has been recognized as a problem for decades. The use of heavy metals in industries and their regular mining increases their concentration in water bodies. Unlike organic compounds, metals cannot degrade, and therefore effective cleanup requires their immobilization to reduce or remove toxicity. A few conventional methods employed to remove heavy metals from wastewater are expensive, require skilled labors and maintenance. Therefore, the use of aquatic plants has come up since...

  8. Response of Listeria monocytogenes-inoculated leafy salad vegetables following irradiation and refrigerated storage under modified atmosphere. Section 3. Studies on the irradiation destruct values for Shigella Sonnie in liquids or on fresh produce, Salmonella and Escherichia Coli O157:H7 on sprouts and post irradiation survival and growth of indigenous microflora on vegetable sprouts and on warm or cold water-washed cut Iceberg Lettuce

    International Nuclear Information System (INIS)

    Consumption of contaminated fresh produce with Salmonella spp., Escherichia coli O157:H7 or Shigella sonnie resulted in confirmed food-borne outbreaks in the United States and elsewhere. Irradiation destruct values of the produce related isolates are not known and were determined after being inoculated on fresh lettuce or sprouts using a gamma source. The resulting destruct values for Salmonella, E. coli O157:H7 and Shigella sonnie were 0.46 ± 0.02, 0.30 ± 0.02, and 0.24 ± 0.03 kGy, respectively. These values are comparable with the published values for the meat-related food-borne isolates. Ionizing irradiation was used as an intervention to reduce the indigenous microbial populations on fresh sprouts and cut lettuce washed in 5 and 47 deg. C water. Microbiological profiles were monitored during refrigerated (4 deg. C) storage and analysed each week for up to three weeks to determine the keeping quality. Regardless of the initial background, after irradiating to 2 kGy, a two log reduction was observed for the total aerobic and coliform counts on the sprouts or lettuce samples. During storage the bacterial counts of the irradiated samples increased but not to the level of the non-irradiated samples. The results indicate that a 2 kGy dose improved the microbial keeping quality of the fresh produce, inhibited microbial spoilage and achieved a 5 log reduction for both the E. coli O157:H7 and Shigella sonnie. The reduced bacterial counts would also provide a margin of safety by also reducing food-borne pathogen levels. (author)

  9. Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

    Energy Technology Data Exchange (ETDEWEB)

    Razinger, Jaka [Department for Environmental Technologies and Biomonitoring, Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje (Slovenia)], E-mail: jaka@ifb.si; Dermastia, Marina [National Institute of Biology, Vecna pot 111, p.p. 141, SI-1001 Ljubljana (Slovenia); Biotechnical Faculty, Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Koce, Jasna Dolenc [Biotechnical Faculty, Department of Biology, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Zrimec, Alexis [Department for Environmental Technologies and Biomonitoring, Institute of Physical Biology, Veliko Mlacevo 59, SI-1290 Grosuplje (Slovenia)

    2008-06-15

    The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl{sub 2} ranging from 0 to 500 {mu}M. High accumulation of cadmium was observed (12,320 {+-} 2155 {mu}g g{sup -1} at 500 {mu}M CdCl{sub 2}), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl{sub 2} exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1 {mu}M CdCl{sub 2} (137 {+-} 13.2% of the control) and its reduction to only 47.4 {+-} 4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed. - The increase of total antioxidative potential at low cadmium concentration is one of the mechanisms that helps duckweed to cope with cadmium-induced oxidative stress.

  10. Effect of electromagnetic fields on duckweed (lemna minor) and alga (chlorella kessleri)

    International Nuclear Information System (INIS)

    Electricity produces extremely low frequency fields (50-60 Hz) while various kinds of radiofrequency fields (10 MHz-300 GHz) are used to transmit information (TV, radio, mobile phones and satellite communications). Duckweed (Lemna minor) and green algae (Chlorella kessleri) were exposed to the magnetic field of 50 Hz in a Helmholtz coil, to an electric field of 50 Hz between two parallel circle electrodes, and to electromagnetic fields of 400 and 900 MHz in a Gigahertz Transversal Electromagnetic Mode cell. The relative growth of Lemna minor exposed to extremely low frequency alternating magnetic field of 50 Hz (1 mT) for 24 hours was slightly reduced at the beginning of the experiment while a 50 Hz electric field (25 kV/m) slightly reduced its growth during the second week of the experiment. Radio frequencies of 400 and 900 MHz (23 V/m) applied for two hours decreased the duckweed growth after the third day, but only 900 MHz affected it significantly. The rate of photosynthesis in green algae increased after exposure to the magnetic field of 50 Hz, but decreased after exposure to the electric field of 50 Hz. Radio frequencies of 400 and 900 MHz generally increased its rate of photosynthesis.(author)

  11. Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

    International Nuclear Information System (INIS)

    The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl2 ranging from 0 to 500 ?M. High accumulation of cadmium was observed (12,320 ± 2155 ?g g-1 at 500 ?M CdCl2), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1 ?M CdCl2 (137 ± 13.2% of the control) and its reduction to only 47.4 ± 4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed. - The increase of total antioxidative potential at low cadmium concentration is one of the mechanisms that helps duckweed to cope with cadmium-induced oxidative stress

  12. Increase of starch accumulation in the duckweed Lemna minor under abiotic stress

    Directory of Open Access Journals (Sweden)

    K. SOWJANYA SREE

    2014-06-01

    Full Text Available Abiotic stresses often result in suppression of photosynthesis and plant growth. Using the duckweed species Lemna minor and subjecting these plants to abiotic stress viz., (1 application of heavy metals, (2 application of salt (NaCl, and (3 lack of phosphate, we showed that photosynthesis was inhibited to a lesser degree than plant growth. This became evident by detecting the accumulation of starch under these conditions: (1 Cadmium ions and other heavy metals induced the accumulation of starch after 4 days of treatment at concentrations when growth was almost completely suppressed (e. g. 80 %. (2 Application of NaCl at a concentration of 150 mM also resulted in accumulation of starch but the highest level could be observed only after 7 days. (3 Depletion of phosphate in the growth medium had similar effects leading to starch accumulation after 14 days of treatment. Starch can accumulate to approximately 50% of dry mass under the three different conditions. We suggest the following common molecular mechanism: The stress factor suppresses growth more effectively than photosynthesis. The resulting surplus of carbohydrates is then stored as starch. This hypothesis has biotechnological relevance since stressors may be applied for increasing starch accumulation in duckweed and thus could be used to optimize bioethanol production from this aquatic crop.

  13. Stimulation of nitrogen removal in the rhizosphere of aquatic duckweed by root exudate components.

    Science.gov (United States)

    Lu, Yufang; Zhou, Yingru; Nakai, Satoshi; Hosomi, Masaaki; Zhang, Hailin; Kronzucker, Herbert J; Shi, Weiming

    2014-03-01

    Plants can stimulate bacterial nitrogen (N) removal by secretion of root exudates that may serve as carbon sources as well as non-nutrient signals for denitrification. However, there is a lack of knowledge about the specific non-nutrient compounds involved in this stimulation. Here, we use a continuous root exudate-trapping system in two common aquatic duckweed species, Spirodela polyrrhiza (HZ1) and Lemna minor (WX3), under natural and aseptic conditions. An activity-guided bioassay using denitrifying bacterium Pseudomonas fluorescens showed that crude root exudates of the two species strongly enhanced the nitrogen-removal efficiency (NRE) of P. fluorescens (P duckweed released fatty acid methyl esters and fatty acid amides, specifically: methyl hexadecanoate, methyl (Z)-7-hexadecenoate, methyl dodecanoate, methyl-12-hydroxystearate, oleamide, and erucamide. Methyl (Z)-7-hexadecenoate and erucamide emerged as the effective N-removal stimulants (maximum stimulation of 25.9 and 33.4%, respectively), while none of the other tested compounds showed stimulatory effects. These findings provide the first evidence for a function of fatty acid methyl esters and fatty acid amides in stimulating N removal of denitrifying bacteria, affording insight into the "crosstalk" between aquatic plants and bacteria in the rhizosphere. PMID:24271005

  14. The influence of duckweed species diversity on ecophysiological tolerance to copper exposure.

    Science.gov (United States)

    Zhao, Zhao; Shi, Huijuan; Duan, Dongzhu; Li, Hongmei; Lei, Tingwen; Wang, Maolin; Zhao, Hai; Zhao, Yun

    2015-07-01

    In excess, copper is toxic to plants. In the plants, Landoltia punctata and Lemna minor grown in mixed and monoculture, the effects of exposure to varying concentrations of copper (0.01, 0.1, 0.5 and 1mgL(-1) Cu) for seven days were assessed by measuring changes in the chlorophyll, protein and malondialdehyde (MDA) content, catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) activity. According to results, Cu levels in plants increased with increasing Cu concentration. The level of photosynthetic pigments and crude proteins decreased only upon exposure to high Cu concentrations. However, the starch and malondialdehyde (MDA) content increased. These results suggested a stress alleviation that was possibly the result of antioxidants such as CAT and SOD, the activities of which increased with increasing Cu levels. APX activity increased in L. punctata, but decreased in L. minor, under monoculture or mixed culture conditions. In addition, the duckweed in mixed culture exhibited increased antioxidant enzyme activities which provide increased resistance to copper in moderate copper concentrations. As the copper concentration increased, the duckweed in the mixed culture limited the uptake of copper to avoid toxicity. PMID:25938979

  15. Effects of high ammonium level on biomass accumulation of common duckweed Lemna minor L.

    Science.gov (United States)

    Wang, Wenguo; Yang, Chuang; Tang, Xiaoyu; Gu, Xinjiao; Zhu, Qili; Pan, Ke; Hu, Qichun; Ma, Danwei

    2014-12-01

    Growing common duckweed Lemna minor L. in diluted livestock wastewater is an alternative option for pollutants removal and consequently the accumulated duckweed biomass can be used for bioenergy production. However, the biomass accumulation can be inhibited by high level of ammonium (NH4 (+)) in non-diluted livestock wastewater and the mechanism of ammonium inhibition is not fully understood. In this study, the effect of high concentration of NH4 (+) on L. minor biomass accumulation was investigated using NH4 (+) as sole source of nitrogen (N). NH4 (+)-induced toxicity symptoms were observed when L. minor was exposed to high concentrations of ammonium nitrogen (NH4 (+)-N) after a 7-day cultivation. L. minor exposed to the NH4 (+)-N concentration of 840 mg l(-1) exhibited reduced relative growth rate, contents of carbon (C) and photosynthetic pigments, and C/N ratio. Ammonium irons were inhibitory to the synthesis of photosynthetic pigments and caused C/N imbalance in L. minor. These symptoms could further cause premature senescence of the fronds, and restrain their reproduction, growth and biomass accumulation. L. minor could grow at NH4 (+)-N concentrations of 7-84 mg l(-1) and the optimal NH4 (+)-N concentration was 28 mg l(-1). PMID:25056754

  16. Chromatin organisation in duckweed interphase nuclei in relation to the nuclear DNA content.

    Science.gov (United States)

    Cao, H X; Vu, G T H; Wang, W; Messing, J; Schubert, I

    2015-01-01

    The accessibility of DNA during fundamental processes, such as transcription, replication and DNA repair, is tightly modulated through a dynamic chromatin structure. Differences in large-scale chromatin structure at the microscopic level can be observed as euchromatic and heterochromatic domains in interphase nuclei. Here, key epigenetic marks, including histone H3 methylation and 5-methylcytosine (5-mC) as a DNA modification, were studied cytologically to describe the chromatin organisation of representative species of the five duckweed genera in the context of their nuclear DNA content, which ranged from 158 to 1881 Mbp. All studied duckweeds, including Spirodela polyrhiza with a genome size and repeat proportion similar to that of Arabidopsis thaliana, showed dispersed distribution of heterochromatin signatures (5mC, H3K9me2 and H3K27me1). This immunolabelling pattern resembles that of early developmental stages of Arabidopsis nuclei, with less pronounced heterochromatin chromocenters and heterochromatic marks weakly dispersed throughout the nucleus. PMID:24853858

  17. Pochonia chlamydosporia var. chlamydosporia (Goddard Zare & W. Gams for the management of lettuce infected with Meloidogyne javanica (Treub, 1885

    Directory of Open Access Journals (Sweden)

    José R Viggiano

    2015-06-01

    Full Text Available The application of the nematophagous fungus Pochonia chlamydosporia var. chlamydosporia (Goddard Zare & W. Gams during seedling production of vegetable crops can be an efficient approach to control root-knot nematode. The aim of this study was to evaluate the effect of treating seedlings and/or soil with bionematicide (wettable powder formulation based on chlamydospores from isolate Pc-10 on the Meloidogyne javanica (Treub, 1885 control in lettuce (Lactuca sativa L.. Isolate Pc-10 was diluted in water and applied when watering the seedlings (0, 4.5, 9.0, 13.5, and 18.0 g L-1 and/or to the potted soil (5000 chlamydospores g-1 used for growing lettuce. The soil in each pot was infested with 3000 M. javanica eggs. The number of M. javanica eggs was reduced in lettuce roots when isolate Pc-10 was applied either to seedlings or soil; there was no interaction between application methods. The decrease in the number of eggs was proportional to the increase of isolate Pc-10 applied to seedlings with maximum reduction of 43.5% at the 18 g L-1 dose. When the fungus was applied to the soil, the number of eggs was reduced by 12.3%. Increasing doses of isolate Pc-10 reduced the number of galls up to 21% with the 18 g L-1 dose. Applying bionematicide based on P. chlamydosporia isolate Pc-10 at 18 g L-1 on seedlings controls M. javanica in lettuce.

  18. A SEDIMENT TOXICITY METHOD USING LEMNA MINOR, DUCKWEED

    Science.gov (United States)

    We developed a Lemna minor sediment toxicity test method to assess sediment contaminants which may affect plants. This 96-hour test used 15 ml of sediment and 2 ml of overlying water which was renewed after 48 hours. Sand was used as the control sediment and also to dilute test ...

  19. Common Duckweed (Lemna minor) Is a Versatile High-Throughput Infection Model For the Burkholderia cepacia Complex and Other Pathogenic Bacteria

    OpenAIRE

    Thomson, Euan L.S.; Dennis, Jonathan J

    2013-01-01

    Members of the Burkholderia cepacia complex (Bcc) have emerged in recent decades as problematic pulmonary pathogens of cystic fibrosis (CF) patients, with severe infections progressing to acute necrotizing pneumonia and sepsis. This study presents evidence that Lemna minor (Common duckweed) is useful as a plant model for the Bcc infectious process, and has potential as a model system for bacterial pathogenesis in general. To investigate the relationship between Bcc virulence in duckweed and G...

  20. Effect of dissolved oxygen concentration on lettuce growth in floating hydroponics.

    Science.gov (United States)

    Goto, E; Both, A J; Albright, L D; Langhans, R W; Leed, A R

    1996-12-01

    Lettuce (Lactuca sativa L., cv. Ostinata) growth experiments were carried out to study the effect of dissolved oxygen (DO) concentration on plant growth in a floating hydroponic system. Pure O2 and N2 gas were supplied to the hydroponic system for precise DO control. This system made it easy to increase the DO concentration beyond the maximum (or saturation) concentration possible when bubbling air into water. Eleven day old lettuce seedlings were grown for 24 days under various DO concentrations: sub-saturated, saturated, and super-saturated. There was no significant difference in fresh weight, shoot and root dry weights among the DO concentrations: 2.1 (25% of saturated at 24 degrees C), 4.2 (50%), 8.4 (saturated), and 16.8 (200%) mg/L. The critical DO concentration for vigorous lettuce growth was considered to be lower than 2.1 mg/L. Neither root damage nor delay of shoot growth was observed at any of the studied DO concentrations. PMID:11541573

  1. Use of polishing pond effluents to cultivate lettuce (Lactuca sativa) in a hydroponic system.

    Science.gov (United States)

    Keller, R; Perin, K; Souza, W G; Cruz, L S; Zandonade, E; Cassini, S T A; Goncalves, R F

    2008-01-01

    The sanitary quality and productivity of hydroponic lettuce (Lactuca sativa L.) plants cultivated under greenhouse conditions and treated with effluent from anaerobic reactor + polishing pond followed by physical-chemical treatment was evaluated. Two hydroponic cultivations were performed at summer and winter time at Vitoria-ES, Brazil. The treatments for both cultivations were: T1) conventional nutrient solution, T2) effluent from physical-chemical treatment, T3) effluent from polishing pond, and T4) effluent from polishing pond with 50% dilution. The plants were evaluated for microbial contamination, productivity and nutrient content. In all cases, no significant microbial contamination of lettuce was detected and the levels of macronutrients in the shoot system were similar to those in published reports. In the experiments from summer season, the treatments T1 and T2 resulted in higher production than the T3 and T4 treatments. Plants from T3 and T4 had a less developed root system as a result of reduced oxygenation from competition with the higher algae biomass content from the polishing pond effluent. In the winter season, the effect of the algal biomass was pronounced only in the T3 treatment (undiluted effluent from polishing pond). In conclusion, hydroponic cultivation of lettuce with pond effluent is suitable as a complement to water and nutrients for plants. PMID:19039187

  2. De novo assembly and characterization of germinating lettuce seed transcriptome using Illumina paired-end sequencing.

    Science.gov (United States)

    Liu, Shu-Jun; Song, Shun-Hua; Wang, Wei-Qing; Song, Song-Quan

    2015-11-01

    At supraoptimal temperature, germination of lettuce (Lactuca sativa L.) seeds exhibits a typical germination thermoinhibition, which can be alleviated by sodium nitroprusside (SNP) in a nitric oxide-dependent manner. However, the molecular mechanism of seed germination thermoinhibition and its alleviation by SNP are poorly understood. In the present study, the lettuce seeds imbibed at optimal temperature in water or at supraoptimal temperature with or without 100 μM SNP for different periods of time were used as experimental materials, the total RNA was extracted and sequenced, we gained 147,271,347 raw reads using Illumina paired-end sequencing technique and assembled the transcriptome of germinating lettuce seeds. A total of 51,792 unigenes with a mean length of 849 nucleotides were obtained. Of these unigenes, a total of 29,542 unigenes were annotated by sequence similarity searching in four databases, NCBI non-redundant protein database, SwissProt protein database, euKaryotic Ortholog Groups database, and NCBI nucleotide database. Among the annotated unigenes, 22,276 unigenes were assigned to Gene Ontology database. When all the annotated unigenes were searched against the Kyoto Encyclopedia of Genes and Genomes Pathway database, a total of 8,810 unigenes were mapped to 5 main categories including 260 pathways. We first obtained a lot of unigenes encoding proteins involved in abscisic acid (ABA) signaling in lettuce, including 11 ABA receptors, 94 protein phosphatase 2Cs and 16 sucrose non-fermenting 1-related protein kinases. These results will help us to better understand the molecular mechanism of seed germination, thermoinhibition of seed germination and its alleviation by SNP. PMID:26263518

  3. Tobacco streak virus Isolated from Lettuce

    Directory of Open Access Journals (Sweden)

    F.S. Abtahi

    2009-01-01

    Full Text Available Tobacco streak virus (TSV is an ilarvirus with a worldwide distribution. This virus infects many plants and causes significant yield losses. In this study, 300 samples of lettuce were collected from lettuce fields in Tehran Province. Infected plants show symptoms such as: mosaic, vein clearing, vein necrosis, yellowing and leaf distortion. DAS-ELISA (Double Antibody Sandwich-ELISA was used with a polyclonal antiserum against TSV. Five isolates (T1, T2, T3, T4 and T5, which are collected, respectively from Mohammad Abad (Karaj, Malek Abad (Karaj, Hashtgerd (Karaj, Tarand Balla (Varamin and Deh mah sin (Pishva were inoculated on 29 species of Cucurbitaceae, Amaranthaceae, Solanacea, Compositae, Leguminosae and Chenopodiacea. Chenopodium quinoa 6 days after inoculation showed necrotic local lesions. Gomphrena globosa 10 days after inoculation developed chlorotic local lesions. Systemic symptoms were produced in Datura stramonium. Phaseolus vulgaris cv. Red Kidney 5 days after inoculation developed necrotic local lesions. Nicotiana tabacum 7 days after inoculation showed necrotic and chlorotic local lesions. Nicotiana clevelandii 15 days after inoculation developed leaf distortion and vein necrosis. Lactuca sativa 10-15 days after inoculation developed leaf istortion and mosaic. Reverse Transcription Polymerase Chain Reaction (RT-PCR was performed using one primer pairs designed by DSMZ. An approximately 710 bp fragment was amplified with a specific primer.

  4. Study of Water Quality of Recirculated Water in Aquaponic Systems : Study of speciation of selected metals and characterization of the properties of natural organic matter

    OpenAIRE

    Gjesteland, Ingrid

    2013-01-01

    This thesis describes an extensive study on how water quality changes over time in a small scale recirculating system where waste water from smolt production was used to grow lettuce for commercial use. The treatment effect of lettuce on different solutions was tested and corresponding lettuce yield was evaluated. In order to enhance the treatment effect a rock wool filter was used on certain solutions. Important water quality parameters were measured every day, and the element concentration ...

  5. Exposure to radiofrequency radiation induces oxidative stress in duckweed Lemna minor L

    International Nuclear Information System (INIS)

    Widespread use of radiofrequency radiation emitting devices increased the exposure to electromagnetic fields (EMFs) from 300 MHz to 300 GHz. Various biological effects of exposure to these fields have been documented so far, but very little work has been carried out on plants. The aim of the present work was to investigate the physiological responses of the plant Lemna minor after exposure to radiofrequency EMFs, and in particular, to clarify the possible role of oxidative stress in the observed effects. Duckweed was exposed for 2 h to EMFs of 400 and 900 MHz at field strengths of 10, 23, 41 and 120 V m-1. The effect of a longer exposure time (4 h) and modulation was also investigated. After exposure, parameters of oxidative stress, such as lipid peroxidation, H2O2 content, activities and isoenzyme pattern of antioxidative enzymes as well as HSP70 expression were evaluated. At 400 MHz, lipid peroxidation and H2O2 content were significantly enhanced in duckweed exposed to EMFs of 23 and 120 V m-1 while other exposure treatments did not have an effect. Compared to the controls, the activities of antioxidative enzymes showed different behaviour: catalase (CAT) activity increased after most exposure treatments while pyrogallol (PPX) and ascorbate peroxidase (APX) activities were not changed. Exceptions were reduced PPX and APX activity after longer exposure at 23 V m-1 and increased PPX activity after exposures at 10 and 120 V m-1. By contrast, at 900 MHz almost all exposure treatments significantly increased level of lipid peroxidation and H2O2 content but mostly decreased PPX activity and did not affect CAT activity. Exceptions were exposures to a modulated field and to the field of 120 V m-1 which increased PPX and CAT activity. At this frequency APX activity was significantly decreased after exposure at 10 V m-1 and longer exposure at 23 V m-1 but it increased after a shorter exposure at 23 V m-1. At both frequencies no differences in isoenzyme patterns of antioxidative enzymes or HSP70 level were found between control and exposed plants. Our results showed that non-thermal exposure to investigated radiofrequency fields induced oxidative stress in duckweed as well as unspecific stress responses, especially of antioxidative enzymes. However, the observed effects markedly depended on the field frequencies applied as well as on other exposure parameters (strength, modulation and exposure time). Enhanced lipid peroxidation and H2O2 content accompanied by diminished antioxidative enzymes activity caused by exposure to investigated EMFs, especially at 900 MHz, indicate that oxidative stress could partly be due to changed activities of antioxidative enzymes

  6. 76 FR 81468 - Notice of Decision to Authorize the Importation of Shredded Lettuce From Egypt Into the...

    Science.gov (United States)

    2011-12-28

    ...Authorize the Importation of Shredded Lettuce From Egypt Into the Continental United...continental United States of fresh shredded lettuce from Egypt. Based on the findings of...via the importation of fresh shredded lettuce from Egypt. DATES: Effective...

  7. Lettuce achene invigoration through osmopriming at supraoptimal temperature

    International Nuclear Information System (INIS)

    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)

  8. 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. The collected information will then be correlated to each phase of the growth of the lettuces and to the results for the corresponding growth parameters. This will enable characterization of the microbial communities in the rhizosphere and the understanding of how these populations influence each phase of the plant growth. Conclusions are proposed for further investigations.

  9. Carbon and energy fixation of great duckweed Spirodela polyrhiza growing in swine wastewater.

    Science.gov (United States)

    Wang, Wenguo; Yang, Chuang; Tang, Xiaoyu; Zhu, Qili; Pan, Ke; Cai, Denggao; Hu, Qichun; Ma, Danwei

    2015-10-01

    The ability to fix carbon and energy in swine wastewater of duckweeds was investigated using Spirodela polyrhiza as the model species. Cultures of S. polyrhiza were grown in dilutions of both original swine wastewater (OSW) and anaerobic digestion effluent (ADE) based on total ammonia nitrogen (TAN). Results showed that elevated concentrations of TAN caused decreased growth, carbon fixation, and energy production rates, particularly just after the first rise in two types of swine wastewater. Also, OSW was more suitable for S. polyrhiza cultivation than ADE. Maximum carbon and energy fixation were achieved at OSW-TAN concentrations of 12.08 and 13.07 mg L(-1), respectively. Photosynthetic activity of S. polyrhiza could be inhibited by both nutrient stress (in high-concentration wastewater) and nutrient limitation (in low-concentration wastewater), affecting its growth and ability for carbon-energy fixation. PMID:26036587

  10. Light-Emitting Diodes (LEDs) for Miniature Hydroponic Lettuce

    OpenAIRE

    Michelle Lazaro; Teresita Amore; Kent Kobayashi

    2013-01-01

    There is growing concern about food safety, environmental impact, and efficient energy usage in agricultural production systems. Producing lettuce under artificial lighting could be a solution addressing these concerns. Light-emitting diodes (LEDs) offer the advantages of a narrow light spectrum, low power consumption, and little heat production. The objective of this study was to determine the effects of different light sources on the growth of miniature “Tom Thumb” butterhead lettuce in a ...

  11. Urine as a fertilizer for lettuce grown in greenhouse conditions

    OpenAIRE

    Mburu, Catherine

    2012-01-01

    Human urine has a fertilizer value that can be utilized to ensure sustainability in agriculture. This can be successful when the urine is safely used. In this experiment, urine from the dry toilet of Tampere University of Applied sciences was used to grow Australian Leaf lettuce (Lactuca sativa). According to Finnish regulations concerning lettuce fertilization, the recommended amount of nitrogen is 90 kg N/ha. Thus urine treatment with 90 kg N/ha was used. Additionally, two other treatm...

  12. Transient expression of chicken alpha interferon gene in lettuce*

    OpenAIRE

    Song, Li; Zhao, De-Gang; Yong-jun WU; Li, Yi

    2008-01-01

    We investigated the possibility of producing chicken alpha interferon (ChIFN-α) in transgenic plants. The cDNA encoding ChIFN-α was introduced into lettuce (Lactuca sativa L.) plants by using an agro-infiltration transient expression system. The ChIFN-α gene was correctly transcribed and translated in the lettuce plants according to RT-PCR and ELISA assays. Recombinant protein exhibited antiviral activity in vitro by inhibition of vesicular stomatitis virus (VSV) replication on chicken embryo...

  13. 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. PMID:25553584

  14. Accumulation of 99Tc in duckweed Lemna minor L. as a function of growth rate and 99Tc concentration

    International Nuclear Information System (INIS)

    This study focuses on the question of whether short-term studies can be used to forecast the accumulation of the long-lived fission product 99Tc in duckweed, Lemna minor L., grown in the field; in other words, are the accumulation parameters independent of changing growth rates typical of natural populations of duckweed. Two processes determine the 99Tc accumulation: (i) uptake and release of 99TcO4-, characterised by a concentration factor, Kd, and (ii) first-order reduction and complexation of TcVII, characterised by kred. At various 99Tc concentrations, the growth, total Tc and TcO4- accumulation were monitored over 10 days; parameters were fitted and compared with earlier results. Both Kd and kred turn out to be independent of time, concentration and growth rate up to a concentration of 10-6 mol l-199TcO4-. Concentrations above this level result in toxic effects. The Tc accumulation in field populations of duckweed at Tc concentrations which generally occur in the environment can be forecasted by using the results from short-term experiments

  15. Linear Programming Application to Utilization of Duckweed (Lemna paucicostata in Least-cost Ration Formulation for Broiler Finisher

    Directory of Open Access Journals (Sweden)

    Olorunfemi, Temitope O.S.

    2006-01-01

    Full Text Available This study was on the application of linear programming to the utilization of locally available and non-conventional feedstuff - Duckweed (Lemna paucicostata as dietary component of feed for broilers aged from 6 to 10 weeks old. Linear Programming (LP technique was used to investigate, analyse and determine the most efficient way of compounding the least-cost ration. Mathematical models were constructed, taking into consideration nutrient composition of each of the available ingredient, raw material specifications, costs and nutrient requirements of the broiler finisher`s mash. Simplex algorithm was used in solving the resulting linear programming models. The LP model gave least cost feed formulation containing duckweed as optimum at iteration 15 while the optimum for the control was at iteration 19. The result shows that utilization of diet containing 29.50% of duckweed is cost-effective by reducing the cost of the feed by 20.82% and this will invariably improve profitability in broiler production.

  16. Lead and Cadmium Concentration in Agricultural Crops (Lettuce, Cabbage, Beetroot, and Onion of Isfahan Province, Iran

    Directory of Open Access Journals (Sweden)

    Reza Mohajer

    2014-07-01

    Conclusion: The findings of this study indicated that although most of the sampling plants were contaminated with lead and cadmium, the estimated daily intake of each metal (EDI showed that except lead in lettuce, other crops have EDI below the provisional tolerable daily intake (PTDI recommended by the Institute of Standards and Industrial Research of Iran. In order to better management, preventing pollution and also finding the origin of elements, analyzing heavy metals content in soil, water, and dust of this region is recommended.

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

    OpenAIRE

    Schmitt, A.(Institut für Theoretische Physik, Technische Universität Wien, 1040 , Vienna, Austria); Koch, E.; Stephan, D; Kromphardt, C.; Jahn, M.; KRAUTHAUSEN, H.J; G Forsberg; Werner, S.; AMEIN, T; Wright, S.A.I.; Tinivella, F.; Wolf, 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 different agents of natural origin (micro-organisms, plant derived products, resistance inducers) was tested on moist filter paper, in seed trays under controlled conditions and in the field. In a...

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

    International Nuclear Information System (INIS)

    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)

  19. Evaluating the Efficiency of Lettuce Disinfection According to the Official Protocol in Iran

    OpenAIRE

    B Nomanpour; Mubedi, I; A Shahsavani; Pourmand, MR. (PhD); M Yunesian; M Yarahmadi; K. Naddafi

    2012-01-01

    Background: The objective of this study was to evaluate the efficacy of Sanitization of Lettuce according to the protocols set forth by Iranian Ministry of Health and Medical Education for reducing populations of total coliform, fecal coliform, and helminth eggs present on lettuce.Methods: In the present study, we determined the load of total coliform, fecal coliform, and parasites of lettuce. The lettuce was sanitized by protocol of Iranian Ministry of Health and Medical Education. The proto...

  20. Effects of Biogas byproducts “three-dimensional” Fertilization on Yield and Quality of Lettuce

    OpenAIRE

    Hairong Yuan; Xin Huang; Xiujin Li; Libin Tian; Chao Zhu; Dexun Zou

    2014-01-01

    Effect of three-dimension fertilizing mode (3-DFM) using CO2 and liquid/solid fractions of the digesate from anaerobic digester was investigated in quality and yield of lettuce. CO2, solid fraction of digestate (SFD), and liquid fraction of digestate (LFD) were used as fertilizer for gaseous fertilizer, the base fertilizer, and foliar fertilizer, respectively. The result showed that the 3-DFM was appropriate for lettuce. Lettuce’s plant height, width and number of leaves growth amount were 29...

  1. Potential use of duckweed based anaerobic digester effluent as a feed source for heterotrophic growth of micro-algae

    Science.gov (United States)

    Ahmadi, L.; Dupont, R.

    2013-12-01

    Finding an alternative source of energy for the growing world's demand is a challenging task being considered by many scientists. Various types of renewable energy alternatives are being investigated by researchers around the world. The abundance of duckweed (i.e., Lemna and Wolfia sp.) in wetlands and wastewater lagoons, their rapid growth, and their capacity for nutrient, metal and other contaminant removal from wastewater suggests their potential as an inexpensive source of biomass for biofuel production. Another source of biomass for biofuel and energy production is micro-algae. The large-scale growth of micro-algae can potentially be achieved in a smaller footprint and at a higher rate and lower cost via heterotrophic growth compared to autotrophic growth for specific species that can grow under both conditions. Here we describe two types of research. First, two lab-scale, 5 L anaerobic digesters containing municipal raw wastewater that were set up, maintained and monitored over the course of 6 months using duckweed as the feed source. The pH, salinity, amount of gas production and gas composition were measured on a daily basis. The results from these measurements show that duckweed can be used as a good source of biofuel production in the form of methane gas. The second set of reactors consisted of two 1 L batch fed reactors containing algae (Chlorella vulgaris) grown in the lab environment heterotrophically. The pH and DO were monitored on a daily basis in order to investigate their effect on algae growth. Lipid analysis of the harvested algal biomass was done to investigate the efficiency of harvestable biofuel products. A nutrient solution containing glucose as an energy source was used as the initial feed solution, and the potential substitution of the glucose solution with the organic carbon residue from the duckweed digester effluent was investigated. Methane production, carbon stabilization, and gas composition results from the duckweed fed anaerobic digesters, and the growth and biolipid production of heterotrophic micro-algae fed pure substrate versus residual digester effluent carbon are discussed in detail in this study.

  2. Genetic Variation for Shelf-life of Salad-cut Lettuce in Modified-atmosphere Environments

    Science.gov (United States)

    Minimally processed lettuce (Lactuca sativa L.) is an important component of the lettuce industry. The product is highly perishable; cold storage and modified atmosphere (MA) packaging are used to extend its shelf-life. Given the importance of this market, lettuce cultivars, breeding lines, and pop...

  3. INFLUENCE OF A PERIOD OF ARTIFICIAL LIGHTING ON FORMATION OF LETTUCE SEEDLINGS

    Directory of Open Access Journals (Sweden)

    Abyan M. V.

    2014-09-01

    Full Text Available The article presents a research of reaction of seedlings of lettuce on light duration with sodium lamps when grown in a greenhouse. It was shown that in winter conditions of the Krasnodar Region the intensity of natural light to produce quality seedlings of lettuce is insufficient and additional lighting has a significant influence on the morphology of lettuce seedlings

  4. Antimicrobial activity of oregano oil on iceberg lettuce with different attachment conditions

    Science.gov (United States)

    In this study, the antimicrobial activity of oregano oil was investigated under different attachment conditions of Salmonella spp. to iceberg lettuce. Inoculated lettuce was either not dried or dried for 30 min, 60 min or 120 min, under either static air or moving air. Washing iceberg lettuce with 5...

  5. Exposure to radiofrequency radiation induces oxidative stress in duckweed Lemna minor L

    Energy Technology Data Exchange (ETDEWEB)

    Tkalec, Mirta [Department of Botany, Division of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, HR-10000 Zagreb (Croatia)], E-mail: mtkalec@zg.biol.pmf.hr; Malaric, Kresimir [Faculty of Electrical Engineering and Computing, University of Zagreb, Unska 3, HR-10000 Zagreb (Croatia); Pevalek-Kozlina, Branka [Department of Botany, Division of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, HR-10000 Zagreb (Croatia)

    2007-12-15

    Widespread use of radiofrequency radiation emitting devices increased the exposure to electromagnetic fields (EMFs) from 300 MHz to 300 GHz. Various biological effects of exposure to these fields have been documented so far, but very little work has been carried out on plants. The aim of the present work was to investigate the physiological responses of the plant Lemna minor after exposure to radiofrequency EMFs, and in particular, to clarify the possible role of oxidative stress in the observed effects. Duckweed was exposed for 2 h to EMFs of 400 and 900 MHz at field strengths of 10, 23, 41 and 120 V m{sup -1}. The effect of a longer exposure time (4 h) and modulation was also investigated. After exposure, parameters of oxidative stress, such as lipid peroxidation, H{sub 2}O{sub 2} content, activities and isoenzyme pattern of antioxidative enzymes as well as HSP70 expression were evaluated. At 400 MHz, lipid peroxidation and H{sub 2}O{sub 2} content were significantly enhanced in duckweed exposed to EMFs of 23 and 120 V m{sup -1} while other exposure treatments did not have an effect. Compared to the controls, the activities of antioxidative enzymes showed different behaviour: catalase (CAT) activity increased after most exposure treatments while pyrogallol (PPX) and ascorbate peroxidase (APX) activities were not changed. Exceptions were reduced PPX and APX activity after longer exposure at 23 V m{sup -1} and increased PPX activity after exposures at 10 and 120 V m{sup -1}. By contrast, at 900 MHz almost all exposure treatments significantly increased level of lipid peroxidation and H{sub 2}O{sub 2} content but mostly decreased PPX activity and did not affect CAT activity. Exceptions were exposures to a modulated field and to the field of 120 V m{sup -1} which increased PPX and CAT activity. At this frequency APX activity was significantly decreased after exposure at 10 V m{sup -1} and longer exposure at 23 V m{sup -1} but it increased after a shorter exposure at 23 V m{sup -1}. At both frequencies no differences in isoenzyme patterns of antioxidative enzymes or HSP70 level were found between control and exposed plants. Our results showed that non-thermal exposure to investigated radiofrequency fields induced oxidative stress in duckweed as well as unspecific stress responses, especially of antioxidative enzymes. However, the observed effects markedly depended on the field frequencies applied as well as on other exposure parameters (strength, modulation and exposure time). Enhanced lipid peroxidation and H{sub 2}O{sub 2} content accompanied by diminished antioxidative enzymes activity caused by exposure to investigated EMFs, especially at 900 MHz, indicate that oxidative stress could partly be due to changed activities of antioxidative enzymes.

  6. Detection of Lettuce Discoloration Using Hyperspectral Reflectance Imaging

    Directory of Open Access Journals (Sweden)

    Changyeun Mo

    2015-11-01

    Full Text Available 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)

    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 14C-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 14C-label in the leaves, as well as significantly greater amounts of unmetabolized 14C-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. Phytotoxic mechanisms of bur cucumber seed extracts on lettuce with special reference to analysis of chloroplast proteins, phytohormones, and nutritional elements.

    Science.gov (United States)

    Lee, Seok-Min; Radhakrishnan, Ramalingam; Kang, Sang-Mo; Kim, Jin-Hyo; Lee, In-Yong; Moon, Bong-Kyu; Yoon, Byung-Wook; Lee, In-Jung

    2015-12-01

    Bioherbicides from plant extracts are an effective and environmentally friendly method to prevent weed growth. The present investigation was aimed at determining the inhibitory effect of bur cucumber seed extracts (BSE) on lettuce plant growth. Bur cucumber seeds were ground with water, and two different concentrations of seed extracts (10% and 20%) were prepared and applied to lettuce plants. Decreased plant height, number of leaves, leaf length, leaf width, anProd. Type: FTPd leaf area were found in lettuce exposed to BSE as compared with controls. A significant reduction in lettuce biomass was observed in 20% BSE-treated plants due to the presence of higher amounts of phenolic content in the extracts. Moreover, a significant inhibitory chemical, 2-linoleoyl glycerol, was identified in BSE extracts. The mechanism of plant growth inhibition was assayed in lettuce proteins by 2-dimensional electrophoresis (2-DE) and the LC-MS/MS method. In total, 57 protein spots were detected in plants treated with 20% BSE and control plants. Among these, 39 proteins were down-regulated and 18 proteins were up-regulated in plants exposed to 20% BSE as compared with controls. The presence of low levels of chlorophyll a/b binding protein and oxygen-evolving enhancer protein 1 in BSE-exposed plants reduced photosynthetic pigment synthesis and might be a reason for stunted plant growth. Indeed, the plant-growth stimulating hormone gibberellin was inhibited, and synthesis of stress hormones such as abscisic acid, jasmonic acid, and salicylic acid were triggered in lettuce by the effects of BSE. Uptake of essential nutrients, Ca, Fe, Mg, K, S, and Mo, was deficient and accumulation of the toxic ions Cu, Zn, and Na was higher in BSE-treated plants. The results of this study suggest that extracts of bur cucumber seeds can be an effective eco-friendly bioherbicide for weed control that work by inhibiting mechanisms of photosynthesis and regulating phytohormones and nutritional elements. PMID:26277540

  9. Evaluation of the potential of Pistia stratiotes L. (water lettuce) for bioindication and phytoremediation of aquatic environments contaminated with arsenic / Avaliação do potencial de Pistia stratiotes L. (alface d'água) para a bioindicação e fitorremediação de ambientes aquáticos contaminados com arsênio

    Scientific Electronic Library Online (English)

    FS, Farnese; JA, Oliveira; FS, Lima; GA, Leão; GS, Gusman; LC, Silva.

    2014-08-01

    Full Text Available Espécimes de Pistia stratiotes foram submetidos a cinco concentrações de arsênio (As), durante sete dias. Crescimento, absorção de As, concentração de malondialdeído (MDA), pigmentos fotossintéticos, atividades enzimátic [...] as, concentração de aminoácidos e alterações anatômicas foram avaliadas. O acúmulo de As pelas plantas aumentou com o incremento do metaloide na solução, enquanto que a taxa de crescimento e o teor de pigmentos fotossintéticos diminuiu. O conteúdo MDA aumentou, indicando estresse oxidativo. A atividade de enzimas antioxidantes e os teores de aminoácidos aumentaram nas doses mais baixas de As, declinando nas concentrações mais elevadas. Nas folhas foram observados clorose e necrose. As folhas apresentaram acumulação de amido e aumento da espessura do mesofilo. No sistema radicular houve perda e escurecimento das raízes. Camadas de células formadas nos pontos de inserção da raiz podem ter sido responsáveis pela queda das raízes. Estes resultados indicam que a alface da água apresenta potencial para bioindicação e fitorremediação de ambientes aquáticos contaminados com As. Abstract in english Specimens of Pistia stratiotes were subjected to five concentrations of arsenic (As) for seven days. Growth, As absorption, malondialdehyde (MDA) content, photosynthetic pigments, enzymatic activities, amino acids content and anatomical cha [...] nges were assessed. Plant arsenic accumulation increased with increasing metalloid in the solution, while growth rate and photosynthetic pigment content decreased. The MDA content increased, indicating oxidative stress. Enzymatic activity and amino acids content increased at the lower doses of As, subsequently declining in the higher concentrations. Chlorosis and necrosis were observed in the leaves. Leaves showed starch accumulation and increased thickness of the mesophyll. In the root system, there was a loss and darkening of roots. Cell layers formed at the insertion points on the root stems may have been responsible for the loss of roots. These results indicate that water lettuce shows potential for bioindication and phytoremediation of As-contaminated aquatic environments.

  10. Evaluation of the potential of Pistia stratiotes L. (water lettuce) for bioindication and phytoremediation of aquatic environments contaminated with arsenic / Avaliação do potencial de Pistia stratiotes L. (alface d'água) para a bioindicação e fitorremediação de ambientes aquáticos contaminados com arsênio

    Scientific Electronic Library Online (English)

    FS, Farnese; JA, Oliveira; FS, Lima; GA, Leão; GS, Gusman; LC, Silva.

    2014-08-01

    Full Text Available Espécimes de Pistia stratiotes foram submetidos a cinco concentrações de arsênio (As), durante sete dias. Crescimento, absorção de As, concentração de malondialdeído (MDA), pigmentos fotossintéticos, atividades enzimáticas, concentração de aminoácidos e alterações anatômicas foram avaliadas. O acúmu [...] lo de As pelas plantas aumentou com o incremento do metaloide na solução, enquanto que a taxa de crescimento e o teor de pigmentos fotossintéticos diminuiu. O conteúdo MDA aumentou, indicando estresse oxidativo. A atividade de enzimas antioxidantes e os teores de aminoácidos aumentaram nas doses mais baixas de As, declinando nas concentrações mais elevadas. Nas folhas foram observados clorose e necrose. As folhas apresentaram acumulação de amido e aumento da espessura do mesofilo. No sistema radicular houve perda e escurecimento das raízes. Camadas de células formadas nos pontos de inserção da raiz podem ter sido responsáveis pela queda das raízes. Estes resultados indicam que a alface da água apresenta potencial para bioindicação e fitorremediação de ambientes aquáticos contaminados com As. Abstract in english Specimens of Pistia stratiotes were subjected to five concentrations of arsenic (As) for seven days. Growth, As absorption, malondialdehyde (MDA) content, photosynthetic pigments, enzymatic activities, amino acids content and anatomical changes were assessed. Plant arsenic accumulation increased wit [...] h increasing metalloid in the solution, while growth rate and photosynthetic pigment content decreased. The MDA content increased, indicating oxidative stress. Enzymatic activity and amino acids content increased at the lower doses of As, subsequently declining in the higher concentrations. Chlorosis and necrosis were observed in the leaves. Leaves showed starch accumulation and increased thickness of the mesophyll. In the root system, there was a loss and darkening of roots. Cell layers formed at the insertion points on the root stems may have been responsible for the loss of roots. These results indicate that water lettuce shows potential for bioindication and phytoremediation of As-contaminated aquatic environments.

  11. Photomanipulation of phytochrome in lettuce seeds.

    Science.gov (United States)

    Kendrick, R E; Russell, J H

    1975-08-01

    Seeds of lettuce (Lactuca sativa L. cv. Grand Rapids) were imbibed and given either short irradiation with red or far red light prior to drying or dried under continuous red or far red light. Seeds treated with either short or continuous red germinate in darkness, whereas seeds treated with either short or continuous far red require a short exposure to red light, after a period of imbibition, to stimulate germination. Irradiation of dry red seeds with far red light immediately before sowing results in a marked inhibition of germination. This result was predicted since far red-absorbing form phytochrome can be photoconverted to the intermediate P650 (absorbance maximum 650 nm) in freeze-dried tissue. A similar far red treatment to continuous red seeds is less effective and it is concluded that in these seeds a proportion of total phytochrome is blocked as intermediates between red-absorbing and far red-absorbing form phytochrome, which only form the far red-absorbing form of phytochrome on imbibition. The inhibition of dry short red seeds by far red light can be reversed by an irradiation with short red light given immediately before sowing, confirming that P650 can be photoconverted back to the far red-absorbing form of phytochrome. The results are discussed in relation to seed maturation (dehydration) on the parent plant. PMID:16659296

  12. Potential Uptake of Escherichia coli O157:H7 from Organic Manure into Crisphead Lettuce

    OpenAIRE

    Johannessen, Gro S.; Bengtsson, Gunnar B.; Heier, Berit T.; Bredholt, Sylvia; Wasteson, Yngvild; Rørvik, Liv Marit

    2005-01-01

    To investigate the potential transfer of Escherichia coli O157:H7 from contaminated manure to fresh produce, lettuce seedlings were transplanted into soil fertilized with bovine manure which had been inoculated with approximately 104 CFU g?1 E. coli O157:H7. The lettuce was grown for approximately 50 days in beds in climate-controlled rooms in a greenhouse. As the bacterium was not detected in the edible parts of the lettuce, the outer leaves of the lettuce, or the lettuce roots at harvest it...

  13. Phytoxicity study of the products of wet oxidation of a representative biomass (lettuce)

    Science.gov (United States)

    Onisko, B. L.; Wydeven, T.

    1983-01-01

    In an attempt to verify the results reported previously concerning the phytotoxicity of wet-oxidation (wet-ox) products, lettuce solids were suspended in water and then heated to 548 K for 3.6 ksec (1 hr) under 4.1x10 to the -7 Pa (400 psig at 294 K) oxygen pressure and 1.52x10 to the 8th (1500 psig at 548 K) total pressure. Such treatment resulted in oxidation of 80% of the initial organic carbon to carbon dioxide. Thirty-three percent of the remaining organic carbon was present in acetic acid. Organic nitrogen in the feed was decreased 90% by the wet-ox treatment. Ammonia and nitrogen gas were the main nitrogen products. Analysis of the liquid product of wet-ox indicated that most of the minerals essential for plant growth were present. However, when tested using a lettuce-root growth-rate assay, the solution was toxic. This toxicity was not due to excessive salt or ammonia or to an improper pH. Analysis of the wet-ox solution revealed the presence of silver and chromium, thus implicating reactor corrosion as the cause of the phytotoxicity. Both cation and anion exchange resins removed the silver and the toxicity of the liquid effluent, indicating silver as the toxic component. Uptake of both silver and chromium by lettuce roots correlated with diminished root growth. Toxicity of the solution from wet-ox was not observed when precautions were taken to minimize contact of the liquid in the reactor with the metal reactor components.

  14. Effect of salt stress on growth and physiology in amaranth and lettuce: Implications for bioregenerative life support system

    Science.gov (United States)

    Qin, Lifeng; Guo, Shuangsheng; Ai, Weidang; Tang, Yongkang; Cheng, Quanyong; Chen, Guang

    2013-02-01

    Growing plants can be used to clean waste water in bioregenerative life support system (BLSS). However, NaCl contained in the human urine always restricts plant growth and further reduces the degree of mass cycle closure of the system (i.e. salt stress). This work determined the effect of NaCl stress on physiological characteristics of plants for the life support system. Amaranth (Amaranthus tricolor L. var. Huahong) and leaf lettuce (Lactuca sativa L. var. Luoma) were cultivated at nutrient solutions with different NaCl contents (0, 1000, 5000 and 10,000 ppm, respectively) for 10 to 18 days after planted in the Controlled Ecological Life Support System Experimental Facility in China. Results showed that the two plants have different responses to the salt stress. The amaranth showed higher salt-tolerance with NaCl stress. If NaCl content in the solution is below 5000 ppm, the salt stress effect is insignificant on above-ground biomass output, leaf photosynthesis rate, Fv/Fm, photosynthesis pigment contents, activities of antioxidant enzymes, and inducing lipid peroxidation. On the other hand, the lettuce is sensitive to NaCl which significantly decreases those indices of growth and physiology. Notably, the lettuce remains high productivity of edible biomass in low NaCl stress, although its salt-tolerant limitation is lower than amaranth. Therefore, we recommended that amaranth could be cultivated under a higher NaCl stress condition (<5000 ppm) for NaCl recycle while lettuce should be under a lower NaCl stress (<1000 ppm) for water cleaning in future BLSS.

  15. Comparison between Hydroponically and Conventionally and Organically Grown Lettuces for Taste, Odor, Visual Quality and Texture: A Pilot Study

    OpenAIRE

    Nakamura, Yukiko K; Fannie Zhang; Matthew T. Murphy; Omaye, Stanley T.

    2011-01-01

    Hydroponic production of vegetables is becoming more common. In this study hydroponic lettuce, grown by a local distributor, and conventionally and organically field-grown lettuce, purchased at local retail stores were compared by descriptive analysis for taste, odor, visual quality and texture. Five lettuce varieties were compared; Romaine, Green Leaf, Red Leaf, Butter, and Common lettuce. A twenty-three member sensory panel randomly rated the lettuce using a 5 point scale or a 3 point scale...

  16. Effect of single or combined chemical and natural antimicrobial interventions on Escherichia coli O157:H7, total microbiota and color of packaged spinach and lettuce.

    Science.gov (United States)

    Poimenidou, Sofia V; Bikouli, Vasiliki C; Gardeli, Chryssavgi; Mitsi, Christina; Tarantilis, Petros A; Nychas, George-John; Skandamis, Panagiotis N

    2016-03-01

    Aqueous extract of Origanum vulgare (oregano), sodium hypochlorite (60 and 300ppm of free chlorine), Citrox® (containing citric acid and phenolic compounds [bioflavonoids] as active ingredients), vinegar, lactic acid, and double combinations of Citrox, lactic acid and oregano were evaluated against Escherichia coli O157:H7 and total mesophilic microbiota on fresh-cut spinach and lettuce and for their impact on color of treated vegetables. Spinach and lettuce leaves were inoculated with E. coli O157:H7 to a level of 5-6logCFU/g and immersed in washing solutions for 2 or 5min at 20°C, followed by rinsing with ice water (30s). Bacterial populations on vegetables were enumerated immediately after washing and after storage of the samples at 5°C for 7days under 20% CO2: 80% N2. No significant post-washing microbial reductions were achieved by chlorinated water, whereas after storage total microbiota was increased by 2.4logCFU/g on lettuce. Vinegar wash was the most effective treatment causing E. coli O157:H7 reductions of 1.8-4.3logCFU/g. During storage, pathogen was further decreased to below the detection limit level (microbiota exhibited the highest reductions compared to other treatments. Lactic acid reduced pathogen by 1.6-3.7logCFU/g after washing; however levels of total microbiota increased by up to 2logCFU/g on packaged lettuce during storage. Washing lettuce samples with oregano for 2min resulted in 2.1logCFU/g reduction of E. coli O157:H7. When Citrox was combined with oregano, 3.7-4.0logCFU/g reduction was achieved on spinach and lettuce samples, with no significant effect on color parameters. Additionally, rinsing with ice water after decontamination treatments contributed to maintenance of color of the treated vegetables. In conclusion, the results indicated that vinegar, lactic acid or oregano aqueous extract alone or in combination, as alternative washing solutions to chlorine, may be effectively used to control E. coli O157:H7 and sustain acceptable appearance of fresh cut spinach and lettuce. PMID:26773252

  17. Optimisation of stocking density of Thai silver barb (Barbodes gonionotus Bleeker) in the duckweed-fed four species polyculture system

    OpenAIRE

    Wahab, M. A.; M.E. Azim; Mahmud, A.A.; Kohinoor, A.H.M.; Haque, M. M.

    2001-01-01

    The optimisation of stocking density of Thai silver barb (Barbodes gonionotus) in the polyculture with Labeo rohita, Catla cat/a and Cyprinus cmpio was investigated in seasonal ponds. Three different stocking densities of Thai silver barb i.e., 5,000, 6,000 and 7,000 fingerlings ha-1 were tested with stocking density of carps fixed at the rate of 10,000 fingerlings ha-1 Duckweed was applied to all ponds supplemented with rice bran and oil cake. There were no significant variat...

  18. Reproductive Response of Ewes Fed with Taiwan Grass Hay (Pennisetum purpureum Schum.) Supplemented with Duckweed (Lemna sp. and Spirodela sp.)

    OpenAIRE

    Zetina-Córdoba, P.; Ortega-Cerrilla, M. E.; Sánchez Torres-Esqueda, M. T.; Herrera-Haro, J. G.; Ortega-Jiménez, E.; Reta-Mendiola, J. L.; Vilaboa-Arroniz, J.

    2012-01-01

    The effect of duckweed (DW) supplementation was evaluated on dry matter intake (DMI), presence and duration of estrus, percentage of ewes repeating estrus and pregnancy rate, as well as the concentration of progesterone (P4) in multiparous crossbred ewes from Pelibuey, Dorper, and Katahdin breeds, fed with Taiwan grass hay (TWH). Eighteen ewes with 39.7±4 kg mean body weight, kept in individual pens, were randomly assigned to one of the following treatments: T1: TWH, T2: TWH plus 200 g DW, T3...

  19. To duckweeds (Landoltia punctata), nanoparticulate copper oxide is more inhibitory than the soluble copper in the bulk solution

    OpenAIRE

    Shi, Jiyan; Abid, Aamir D.; Kennedy, Ian M.; Hristova, Krassimira R.; Silk, Wendy K.

    2011-01-01

    CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer–Emmett–Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L?1 soluble copper or by 1.0 mg ...

  20. YIELD RESPONSE OF HEAD LETTUCE ('LACTUCA SATIVA' L.) TO OZONE

    Science.gov (United States)

    Head lettuce (Lactuca sativa L. cv 'Empire') was grown in the field and exposed in open-top chambers to proportional increments of ozone (O3) from full charcoal filtration (CF) to twice ambient O3 concentrations(NF x 2.0). Severe foliar injury developed on young plants exposed to...

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

    DEFF Research Database (Denmark)

    Ethelberg, S.; Lisby, M.

    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 was found to be the vehicle.

  2. Lettuce cultivar influences Xanthomonas campestris pv. vitians population levels

    Science.gov (United States)

    Bacterial Leaf Spot, caused by Xanthomonas campestris pv. vitians (Xcv), is a widespread and economically important disease of lettuce. Cultivars with resistance to Xcv have been identified, but mechanisms for resistance in this pathosystem have not been investigated. We hypothesized that susceptibl...

  3. "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…

  4. 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,…

  5. An Ophiovirus isolated from lettuce with big-vein symptoms.

    Science.gov (United States)

    Roggero, P; Ciuffo, M; Vaira, A M; Accotto, G P; Masenga, V; Milne, R G

    2000-01-01

    Big-vein is a widespread and damaging disease of lettuce, transmitted through soil by the chytrid fungus Olpidium brassicae, and generally supposed to be caused by Lettuce big-vein virus (LBVV; genus Varicosavirus). This virus is reported to have rigid rod-shaped particles, a divided double-stranded RNA genome, and one capsid protein of 48 kD, but has not been isolated or rigorously shown to cause the disease. We provide evidence that a totally different virus, here named Mirafiori lettuce virus (MiLV), is also very frequently associated with lettuce showing big-vein symptoms. MiLV was mechanically transmissible from lettuce to Chenopodium quinoa and to several other herbaceous test plants. The virus was partially purified, and an antiserum prepared, which did not react with LBVV particles in decoration tests. As reported for LBVV, MiLV was labile, soil-transmitted and had a single capsid protein of 48 kD, but the particles morphologically resembled those of ophioviruses, and like these, MiLV had a genome of three RNA segments approximately 8.5, 1.9 and 1.7 kb in size. MiLV preparations reacted strongly in Western blots and in ISEM with antiserum to Tulip mild mottle mosaic virus, an ophiovirus from Japan also apparently Olpidium-transmitted. They reacted weakly but clearly in Western blots with antiserum to Ranunculus white mottle virus, another ophiovirus. When lettuce seedlings were mechanically inoculated with crude or partially purified extracts from MiLV-infected test plants, many became systemically infected with MiLV and some developed big-vein symptoms. Such plants did not react in ELISA using an LBVV antiserum or an antiserum to tobacco stunt virus, and varicosavirus-like particles were never seen in them in the EM after negative staining. We conclude that MiLV is a hitherto undescribed virus assignable to the genus Ophiovirus. The cause or causes of lettuce big-vein disease and the properties of LBVV may need to be re-evaluated in light of our results. PMID:11205109

  6. Cold plasma treatment for the microbiological safety of cabbage, lettuce, and dried figs.

    Science.gov (United States)

    Lee, Hanna; Kim, Jung Eun; Chung, Myong-Soo; Min, Sea C

    2015-10-01

    Microwave-powered cold plasma treatment (CPT) was evaluated as a means to improve the microbiological safety of fresh vegetables and dried fruits. The CPT at 900 W, conducted for 10 min using nitrogen as a plasma-forming gas, inactivated Salmonella Typhimurium inoculated on cabbage and lettuce by approximately 1.5 log CFU/g. The CPT at 400-900 W and 667 Pa, conducted for 1-10 min using a helium-oxygen gas mixture, inactivated Listeria monocytogenes on cabbage by 0.3-2.1 log CFU/g in a time-dependent manner (P < 0.05). The Weibull model adequately described the inactivation of L. monocytogenes on cabbage by CPT. The CPT at the optimum conditions of treatment power (400 W) and time (10 min) inactivated L. monocytogenes on lettuce by 1.8 ± 0.2 log CFU/g. As the water activity of the dried figs increased from 0.70 to 0.93, the reductions in numbers of Escherichia coli O157:H7 and L. monocytogenes on figs increased from 0.5 to 1.3 log CFU/g and from 1.0 to 1.6 log CFU/g, respectively. The microbial inactivation by CPT increased synergistically when the pH of the figs was reduced from 6 to 4. CTPs have potential application to increase the microbiological safety of vegetables and dried fruits. PMID:26187830

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

    International Nuclear Information System (INIS)

    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

  8. Yield and Chemical Composition of Lettuce and Some Soil Characteristics as Affected by Irrigation with Wastewater

    Directory of Open Access Journals (Sweden)

    A. Alizadeh

    2002-04-01

    Full Text Available A field study was conducted at the College of Agriculture, Ferdowsi University of Mashhad, to investigate the effect of irrigation with treated municipal wastewater on the yield and quality of lettuce and some soil characteristics. Five irrigation treatments were applied to a clay loam soil, classified as fine loamy mixed mesic Calcixerollic Xerochrepts, in a randomized block design with 5 replications. The treatments consisted of T1 (Irrigation with treated wastewater over all growing season, T2 (Alternate irrigation with treated wastewater and well water, T3 (Irrigation with well water and application of cattle manure, T4 (Irrigation with well water plus fertilizer N and P, and T5 (Irrigation with well water only as control. Chemical analysis of well water proved to be a suitable source for agriculture. The results showed that the yield was higher in T1, T2, T3 and T4 as compared to the control treatment. Maximum fresh and dry yields were obtained from T3 & T1 and T1 & T3, respectively. Plant tissue analysis showed an increase in macronutrients (N, P, K and heavy metal concentrations in shoots and roots of lettuce in the first four treatments as compared to the control. In T1, iron concentration was maximum while that of cadmium was minimum. Furthermore, microbial contamination was considerably higher in T1 and T2. Soil analysis indicated that in plots treated with wastewater, electrical conductivity, total nitrogen, available phosphorus, soluble boron and heavy metal concentration increased. However, their values were all below international standards. More experiments seem to be necessary in this regard.

  9. Low temperature phosphine fumigation of pre-chilled iceberg lettuce under insulation cover for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae).

    Science.gov (United States)

    Fumigation of chilled iceberg lettuce under an insulation cover was studied to develop economical alternatives to conduct low temperature phosphine fumigation for control of western flower thrips, Frankliniella occidentalis (Pergande), on exported lettuce. Vacuum cooled commercial iceberg lettuce o...

  10. Paenibacillus lemnae sp. nov., an endophytic bacterium of duckweed (Lemna aequinoctialis).

    Science.gov (United States)

    Kittiwongwattana, Chokchai; Thawai, Chitti

    2015-01-01

    A Gram-stain-variable, rod-shaped and endospore-forming bacterium, designated strain L7-75, was isolated from duckweed (Lemna aequinoctialis). Cells were motile with a monopolar flagellum. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain L7-75(T) belonged to the genus Paenibacillus, and the closest phylogenetically related species were Paenibacillus uliginis N3/975(T) (98.5% 16S rRNA gene sequence similarity), Paenibacillus purispatii ES_M17(T) (98.5%), Paenibacillus lactis MB 1871(T) (98.2%), Paenibacillus campinasensis 324(T) (97.7%), Paenibacillus glucanolyticus S93(T) (97.7%) and Paenibacillus lautus ATCC 43898(T) (97.4%). Growth of strain L7-75(T) was observed at pH 7-10 and at 20-40 °C, and NaCl concentrations up to 5% (w/v) were tolerated. Major cellular fatty acids included anteiso-C15?:?0, C16?:?0 and anteiso-C17:0 that were present at 36.0%, 14.2?% and 10.0% of the total cellular fatty acid profile, respectively. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidyl-N-methylethanolamine. MK-7 was the predominant menaquinone. The diamino acid found in the cell-wall peptidoglycan was meso-diaminopimelic acid. The DNA G+C content was 49.1 mol% (Tm). DNA-DNA relatedness values between strain L7-75(T) and its closest relatives ranged from 4.4 to 47.8%. These results indicate that strain L7-75(T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus lemnae sp. nov. is proposed. The type strain is L7-75(T) (?=?BCC 67838(T)?=?NBRC 109972(T)). PMID:25288280

  11. Efeitos da cobertura do solo com filme de polietileno azul no consumo de água da cultura da alface cultivada em estufa / Effects of the soil covering with blue colored polyethylene film on lettuce crop consumptive water-use in a gree

    Scientific Electronic Library Online (English)

    Alexandre O., Gonçalves; Maria A., Fagnani; José G., Peres.

    2005-12-01

    Full Text Available A cobertura do solo é uma prática agrícola que visa, principalmente, a controlar as plantas invasoras, a diminuir as perdas de água por evaporação do solo e a facilitar a colheita e a comercialização, uma vez que o produto se torna mais limpo e sadio. Porém, ao se cobrir o solo, também são alterados [...] parâmetros importantes do microclima e, conseqüentemente, a germinação das sementes, o crescimento das raízes, a absorção de água e nutrientes, a atividade metabólica das plantas e o armazenamento de carboidratos. O objetivo do presente trabalho foi avaliar o efeito da cobertura do solo com filme de polietileno azul no consumo de água da cultura da alface (Lactuca sativa L.). O experimento foi instalado em uma estufa convencional, no município de Araras - SP, e conduzido durante o período de 22-3-2001 a 1º-5-2001. O consumo de água foi medido em dois lisímetros de pesagem instalados no interior da estufa. O espaçamento da cultura foi de 0,25 m x 0,25 m. Também foi avaliado o índice de área foliar (IAF) em seis épocas distintas e determinada a eficiência do uso de água (EU) ao final do ciclo da cultura. O delineamento estatístico foi o de blocos inteiramente casualizados, com dois tratamentos, "solo descoberto" e "solo coberto". O consumo médio de água foi de 4,17 mm dia-1 para o tratamento "solo descoberto" e de 3,11 mm dia-1 para o tratamento "solo coberto". O índice médio de área foliar não diferiu estatisticamente entre os tratamentos. Abstract in english The covering of the soil is an agricultural practice that intends to control the harmful herbs, to reduce the losses of water by evaporation of the soil, and to facilitate the harvest and the commercialization, once the product is cleaner and healthier. However, when the soil is covered important mi [...] croclimatic parameters are also altered, and consequently the germination of seeds, the growth of roots, the absorption of water and nutrients, the metabolic activity of the plants and the carbohydrates storage. The current trial intended to evaluate the effect of soil covering with blue colored film on consumptive water-use in a lettuce crop (Lactuca sativa, L.). The experiment was carried out in a plastic greenhouse in Araras - São Paulo State, Brazil from March 3rd, 2001 to May 5th, 2001. The consumptive water-use was measured through two weighing lysimeter installed inside the greenhouse. Crop spacing was 0.25 m x 0.25 m and the color of the film above soil was blue. Leaf area index (IAF), was measured six times (7; 14; 21; 28; 35; 40 days after transplant) and the water-use efficiency (EU) was measured at the end. The experimental design was subdivided portions with two treatments, "bare soil" and "covered soil". The average consumptive water-use was 4.17 mm day-1 to the "bare soil" treatment and 3.11 mm day-1 to the "covered soil" treatment. The final leaf area index was 25.23 to the "bare soil" treatment and 24.39 to the "covered soil" treatment, and there was no statistical difference between then.

  12. Microbial community and removal of nitrogen via the addition of a carrier in a pilot-scale duckweed-based wastewater treatment system.

    Science.gov (United States)

    Zhao, Yonggui; Fang, Yang; Jin, Yanling; Huang, Jun; Ma, Xinrong; He, Kaize; He, Zhiming; Wang, Feng; Zhao, Hai

    2015-03-01

    Carriers were added to a pilot-scale duckweed-based (Lemna japonica 0223) wastewater treatment system to immobilize and enhance microorganisms. This system and another parallel duckweed system without carriers were operated for 1.5 years. The results indicated the addition of the carrier did not significantly affect the growth and composition of duckweed, the recovery of total nitrogen (TN), total phosphorus (TP) and CO2 or the removal of TP. However, it significantly improved the removal efficiency of TN and NH4(+)-N (by 19.97% and 15.02%, respectively). The use of 454 pyrosequencing revealed large differences of the microbial communities between the different components within a system and similarities within the same components between the two systems. The carrier biofilm had the highest bacterial diversity and relative abundance of nitrifying bacteria (3%) and denitrifying bacteria (24% of Rhodocyclaceae), which improved nitrogen removal of the system. An efficient N-removal duckweed system with enhanced microorganisms was established. PMID:25579229

  13. Ultralow oxygen treatment for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), on iceberg lettuce. II. Pre-treatment on lettuce tolerance and sequential controlled atmosphere

    Science.gov (United States)

    Pre-stored iceberg lettuce under normal atmosphere and controlled atmosphere (CA) with about 3% oxygen at low temperature for one week was compared with fresh lettuce for their response to 2-day ultralow oxygen (ULO) treatment at 10 degrees C for control of western flower thrips. For both atmospheri...

  14. Effect of Wastewater from Quetta City on the Germination and Seedling Growth of Lettuce (Lactuca sativa L.

    Directory of Open Access Journals (Sweden)

    Zahoor Ahmad Bazai

    2006-01-01

    Full Text Available This study was concerned to the effects of 5 various level of polluted water of three different localities of Quetta city (viz., Chiltan Ghee Mill, Chiltan Town and Zarghoon Town on seed germination and seedling growth of Lettuce (Lactuca sativa L.. The Lettuce was taken as a test plant and its seeds were germinated in petri-dishes in the Laboratory. Results showed that seed germination was significantly reduced and delayed as the concentration of wastewater (domestic and industrial effluents increased. Seedling growth (radical and plumule length also showed adverse effect in response to increasing level of polluted water. Whereas, plumule growth was comparatively better than that of radical subjected to initial doses of polluted water. However, by comparing the source of polluted water, maximum reduction in germination and seedling growth were obtained in the effluents of Chiltan Ghee Mill followed by domestic sewage of Chiltan and Zarghoon towns, respectively. It can be safely concluded that polluted water is becoming a threat for the crops with the passage of time as more and more wastes are becoming the part of it. Therefore, it is necessary to investigate the effects of polluted water on plants. Through appropriate awareness campaigns the communities in general and notables in particular, should be made aware of the harmful effects of the activity within the traditional norms and practices.

  15. Effect of temperature and type of packages on nitrates and nitrites content in lettuce

    Directory of Open Access Journals (Sweden)

    Józef B?kowski

    2013-12-01

    Full Text Available Lettuce wrapped in unperforated PE film, perforated PE film, stretch film and without wrapping was stored at 1, 6, 20 and 28°C. Freshly harvested lettuce and after one day of storage, independently on storage conditions, did not contains nitrites„ During storage of lettuce at 1°C only one time small quantities of nitrites (4.3 mg NO2/kg fresh matter were found - after twelve days storage in perforated PE film. Storage of lettuce longer than 7 days at 6°C caused formation of nitrites. Lettuce stored at 20 and 28°C in unperforated PE film contained nitrites already after 2 or 3 days of storage. Decline of nitrates during storage of lettuce was independent from film used to wrapping.

  16. Comparative study on the sensitivity of turions and active fronds of giant duckweed (Spirodela polyrhiza (L.) Schleiden) to heavy metal treatments.

    Science.gov (United States)

    Oláh, Viktor; Hepp, Anna; Mészáros, Ilona

    2015-08-01

    Standard ecotoxicological test procedures use only active forms of aquatic plants. The potential effects of toxicants on vegetative propagules, which play an important role in the survival of several aquatic plant species, is not well understood. Because turion-like resting propagules overwinter on the water bottom in temperate regions, they could be exposed to contaminants for longer periods than active plants. Due to its turion producing capability, giant duckweed (Spirodela polyrhiza) is widely used in studying morphogenesis, dormancy, and activation mechanisms in plants. It is also suitable for ecotoxicological purposes. The present work aims to compare the growth inhibition sensitivity of active (normal frond) and overwintering (turion) forms of S. polyrhiza to concentrations of nickel (Ni), cadmium (Cd) and hexavalent chromium (Cr) ranging from 0 to 100mgL(-1). The results indicated that in general, resting turions have higher heavy metal tolerance than active fronds. Cd proved to be the most toxic heavy metal to S. polyrhiza active frond cultures because it induced rapid turion formation. In contrast, the toxicity of Ni and Cr were found to be similar but lower than the effects of Cd. Cr treatments up to 10mgL(-1) did not result in any future negative effects on turion activation. Turions did not survive heavy metal treatments at higher concentrations of Cr. Cd and Ni treatments affected both the floating-up and germination of turions but did not significantly affect the vigor of sprouts. Higher concentrations (of 100mgL(-1)) Cd completely inhibited germination. PMID:25777504

  17. Effects of nickel on the chloroplasts of the duckweeds Spirodela polyrhiza and Lemna minor and their possible use in biomonitoring and phytoremediation.

    Science.gov (United States)

    Appenroth, K-J; Krech, K; Keresztes, A; Fischer, W; Koloczek, H

    2010-01-01

    Toxic effects of Ni(2+) on the chloroplasts of the two duckweed species Spirodela polyrhiza, clone SJ and Lemna minor, clone St were investigated according to the ISO 20079 protocol. Ni(2+) induced a transition from chloroplasts to chloro-amyloplasts and amylo-chloroplasts, but not to gerontoplasts, as shown by electron microscopy. The contents of the chlorophylls a and b decreased strongly, whereas that of carotenoids remained approximately constant. Most striking was, however, the accumulation of transitory starch. Bell-shaped dose-response curves showed that Spirodela and Lemna amassed maximum starch contents of approximately 10% and 7%, respectively, on a fresh weight basis. Because Ni(2+) in the concentrations applied does not stimulate photosynthesis, the Ni(2+)-induced starch accumulation indicates that the export of carbohydrates out of the plastids decreased, most probably due to the lower demand of the rest of the cells as a result of the Ni(2+)-dependent inhibition of growth. The half-maximal concentrations for inhibition of the fresh weight increase over the 7-day test period were 3.7 microM and 6.6 microM for Spirodela and Lemna, respectively: Spirodela was thus somewhat more sensitive to the heavy metal. Both species accumulated approximately 3g of Ni(2+) per kg of dry weight after application of 100 microM NiCl(2). Because of their high sensitivity to phytotoxic effects, however, Spirodela and Lemna do not appear to be particularly suitable for phytoremediation of Ni(2+)-contaminated waste water. The high sensitivity to Ni(2+) makes them instead a suitable system for ecotoxicological testing in accordance with the ISO 20079 protocol. PMID:19945735

  18. Comparative Study of Ascorbic Acid and Tocopherol Concentrations in Hydroponic- and Soil-Grown Lettuces

    OpenAIRE

    Drew N. Buchanan; Omaye, Stanley T.

    2013-01-01

    Hydroponically-grown produce may be a way of helping to feed the world a variety of fruits and vegetables, regardless of soil quality, space availability or climate. The objective of this study was to determine whether hydroponicallygrown lettuce contains as much ascorbic acid and tocopherol as soil-grown lettuce. We analyzed four varieties of lettuce, including: Waldmann’s Dark Green, Red Lollo Antago, Red Romaine Annapolis, and Butterleaf. The tocopherol content of hydroponically-grown Wald...

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

    Scientific Electronic Library Online (English)

    Oscar V, Bautista; Gerhard, Fischer; Julián F, Cárdenas.

    2013-04-01

    Full Text Available La producción hortícola en la Sabana de Bogotá tiene como principales fuentes hídricas al distrito de riego La Ramada y al rio Bogotá, el cual lleva en su cauce materiales contaminantes como metales pesados, provenientes de las diferentes actividades industriales y domésticas de la Sabana. Estos con [...] taminantes afectan la producción de cultivos en esta zona. En el presente estudio, bajo condiciones de laboratorio, se evaluó el efecto del cadmio (Cd) y cromo (Cr) en tres concentraciones (25, 35 y 50 µM L-1), sobre la imbibición, germinación y elongación radical de lechuga (Lactuca sativa var. Batavia), acelga (Beta vulgaris var. cicla "White Ribbed") y espinaca (Spinacia oleracea híbrida 424), tres especies que son ampliamente cultivadas en la zona. Se encontró una susceptibilidad diferente a los dos compuestos metálicos en cada especie. En lechuga, en el último día de la observación, las tres soluciones de Cd disminuyeron el aumento del peso fresco de las semillas (imbibición), mientras este ocurrió en acelga solamente a 25 µM L-1 de Cd. Cadmio afectó la germinación en 46%, 97% y 8% en acelga, lechuga y espinaca, respectivamente; también, este metal redujo la elongación radical hasta un 57%, 89% y 56% en las tres especies, respectivamente. El Cr no mostró efectos tan negativos, pero redujo la germinación de acelga (29%), lechuga (6%) y espinaca (34%), comparado al control Abstract in english 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

  20. Dynamic Model as Attainment Effort of Nitrogen Synchronization at Lettuce Cultivation with Green Manure Paitan

    Directory of Open Access Journals (Sweden)

    Yuni Agung Nugroho

    2009-05-01

    Full Text Available Lettuce (Lactuca sativa is vegetable crop that consumed part of the leaf and harvested at a phase of vegetative. Nitrogen play important role in growth at phase of vegetative. Nitrogen in spacious have the character of easy to lose because of leaching. Increasing yield of lettuce can be done by improving Nitrogen synchronization, that is precisely usage moment with ready moment of N during and amount of its. The research was aimed to study of the pattern nitrogen requirement for lettuce crop, ready pattern of nitrogen by Tithonia diversifolia and design nitrogen synchronization model between lettuce crop with green manure of T. diversifolia. The research were divided in two phases that are phase research 1: Dynamic modeling for nitrogen synchronization on lettuce cultivation by green manure of T. diversifolia, and phase research 2: Fertilizer technology of high nitrogen synchronization on lettuce cultivation by green manure of T. diversifolia. The result of phase research 1 (first year research shows that dynamic model of N requirement by lettuce crop, release and availability model of N by T. diversifolia and synchronization model of N between requirement of N lettuce with release and availability of N by T. diversifolia. The dynamic model indicate that giving 10 t ha-1 of T. diversifolia which given 2 weeks before transplanting at lettuce crop can support high result and growth because happened good synchronization of N.

  1. Degradation of cyprodinil, fludioxonil, cyfluthrin and pymetrozine on lettuce after different application methods.

    Science.gov (United States)

    Cabizza, Maddalena; Satta, Maurizio; Falconi, Susanna; Onano, Monica; Uccheddu, Giovanni

    2007-01-01

    Degradation of two fungicides (cyprodinil and fludioxonil) and two insecticides (cyfluthrin and pymetrozine) applied on iceberg and romaine lettuce under field conditions with different methods (portable mistblower and chemigation) was studied field data showed that both distribution methods and lettuce cultivar affect the degradation trends of examined pesticides. In these trials the residues of all active ingredients after pre-harvest time were less than fifty's maximum residue levels; the values in the romaine cultivar were generally higher than those in iceberg lettuce. After pre-harvest time residues of pesticides applied on romaine lettuce by portable motor sprayer were always higher than those obtained by the chemigation system. PMID:17763031

  2. Screening for resistance to lettuce downy mildew (Bremia lactucae)

    International Nuclear Information System (INIS)

    Screening methods of Lactuca spp. for resistance to Bremia lactucae (lettuce downy mildew) are described in this chapter. Procedures of isolation, cultivation and maintenance of B. lactucae isolates are summarised. Resistance screening can be carried out either on lettuce seedlings, detached cotyledon leaves, leaf disks or parts of true leaves from adult plants. Methodology of inoculum preparation, inoculation and incubation conditions is described. For the assessment infection degree, a qualitative or quantitative approach is used. A basic differential set of Lactuca spp: used for testing B. lactucae isolates and virulence phenotypes of the most important B. lactucae races was established, including the denomination of races by the sextet code. The methods described have a broad application both in practice and research. They are useful for resistance screening of new breeding material, for searching for new sources of resistance in Lactuca spp. germplasm, for investigating plant resistance mechanisms and also for the study of virulence variation in B. lactucae isolates and populations. (author)

  3. 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.

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

    International Nuclear Information System (INIS)

    [1,2-14C]-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)

  5. Behavior of Shiga toxigenic Escherichia coli relevant to lettuce washing processes and consideration of factors for evaluating washing process surrogates.

    Science.gov (United States)

    Deng, Kaiping; Wang, Xue; Yen, Li-Han; Ding, Hongliu; Tortorello, Mary Lou

    2014-11-01

    Postharvest processes for fresh produce commonly include washing in water containing antimicrobial chemicals, such as chlorine; however, if the antimicrobials are not present in sufficient levels, washing can promote the spread of contamination that might be present. To understand cross-contamination risk during washing, we tested a collection of Shiga toxigenic Escherichia coli (STEC), including O157:H7 and other non-O157 strains, for certain traits during washing of fresh-cut lettuce, i.e., sensitivity to sublethal chlorine levels and ability to cross-contaminate (detach from and attach to) lettuce in the presence of sublethal chlorine levels. Nonpathogenic E. coli Nissle 1917 (EcN) and Pediococcus pentosaceus lactic acid bacterial species (LAB) were included as potential washing process validation surrogates. As measured by extension of the lag phase of growth in media containing 0.15 ppm of chlorine, chlorine sensitivity varied among the STECs. Cross-contamination was assessed by evaluating transfer of bacteria from inoculated to uninoculated leaves during washing. Without chlorine, similar transfer to wash water and uninoculated leaves was shown. In 1 ppm of chlorine, cross-contamination was not detected with most strains, except for the substantial transfer by a STEC O111 strain and EcN in some replicates. Strain O111 and EcN showed less inactivation in 0.25 ppm of chlorine water compared with O157 (P < 0.05). LAB showed similar transfer and similar chlorine inactivation to O157. Considering together the sublethal chlorine sensitivity and detachment/attachment traits, neither EcN nor LAB displayed optimal characteristics as washing process surrogates for the STEC strains, although further evaluation is needed. This work demonstrated a range of behaviors of STEC strains during lettuce washing and may be helpful in hazard characterization, identifying factors to consider for evaluating washing process efficacy, and identifying phenotypic traits to select surrogates to validate washing processes. PMID:25364918

  6. Organic Crop Management Enhances Chicoric Acid Content in Lettuce

    OpenAIRE

    Channa B. Rajashekar; Myung-Min Oh; Edward E. Carey

    2012-01-01

    L- chicoric acid is a dominant phenolic compound in lettuce (Lactuca sativa L.) and has been shown to accumulate in response to many abiotic stresses and crop management practices. It is a potent inhibitor of human immunodeficiency virus (HIV-1) integrase needed for the replication of this virus and for the productive infection of the host cell. L- chicoric acid has been found to act synergistically in combination with anti-HIV drugs used for treating acquired immuno-deficiency disorder (AIDS...

  7. Outbreak of Shigella sonnei infection traced to imported iceberg lettuce.

    OpenAIRE

    Kapperud, G; Rørvik, L M; Hasseltvedt, V; Høiby, E A; Iversen, B G; Staveland, K; Johnsen, G; Leitao, J.; Herikstad, H.; Andersson, Y.

    1995-01-01

    In the period from May through June 1994, an increase in the number of domestic cases of Shigella sonnei infection was detected in several European countries, including Norway, Sweden, and the United Kingdom. In all three countries epidemiological evidence incriminated imported iceberg lettuce of Spanish origin as the vehicle of transmission. The outbreaks shared a number of common features: a predominance of adults among the case patients, the presence of double infections with other enterop...

  8. Uptake of uranium by lettuce (Lactuca sativa L.) in natural uranium contaminated soils in order to assess chemical risk for consumers

    OpenAIRE

    Neves, O.; M. M. Abreu; Vicente, E.M.

    2008-01-01

    Uranium mining activity in Cunha Baixa (Portugal) village has left a legacy of polluted soils and irrigation water. A controlled field experiment was conducted with lettuce (Lactuca sativa L.) in an agricultural area nearby the abandoned mine in order to evaluate uranium uptake and distribution in roots and leaves as well as ascertain levels of uranium intake by the local inhabitants from plant consuming. Two soils with different average uranium content (38 and 106 ...

  9. The Use of Green Fluorescent Protein-Tagged Recombinant Viruses to Test Lettuce mosaic virus Resistance in Lettuce.

    Science.gov (United States)

    Candresse, T; Le Gall, O; Maisonneuve, B; German-Retana, S; Redondo, E

    2002-02-01

    ABSTRACT Seed certification and the use of cultivars containing one of two, probably allelic, recessive genes, mo1(1) and mo1(2), are the principal control methods for Lettuce mosaic virus (LMV) in lettuce. Although for a few LMV isolates, mo1(2) confers resistance with most isolates, the genes mo1(1) or mo1(2) confer a tolerance, and virus accumulation is readily detected in mo1-carrying plants. This phenotype complicates evaluation of the resistance status, in particular for mo1(1), for which there are no viral strains against which a true resistance is expressed. Two green fluorescent protein (GFP)-tagged viruses were constructed, derived from a non-resistance breaking isolate (LMV-0) and from a resistance-breaking isolate (LMV-E). An evaluation of 101 cultivars of known status was carried out with these recombinant viruses. Using the LMV-0-derived recombinant, identification of mo1-carrying cultivars was simple because, contrary to its wild-type parent, systemic movement of LMV-0-GFP was abolished in resistant plants. This assay detected four cases of misidentification of resistance status. In all these cases, further tests confirmed that the prior resistance status information was incorrect, so that a 100% correlation was observed between LMV-0-GFP behavior and the mo1 resistance status. Similarly, the LMV-E-derived recombinant allowed the identification of mo1(2) lettuce lines because its systemic movement was restricted in mo1(2) lines but not in susceptible or in mo1(1) lines. The tagged viruses were able to systemically invade another host, pea, irrespective of its resistance status against another member of the genus Potyvirus, Pea seed-borne mosaic virus. The use of these recombinant viruses could therefore greatly facilitate LMV resistance evaluation and speed up lettuce breeding programs. PMID:18943090

  10. 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

    ...Analysis for the Importation of Shredded Lettuce From Egypt AGENCY: Animal and Plant Health...continental United States of fresh shredded lettuce from Egypt. Based on this analysis...via the importation of fresh shredded lettuce from Egypt. We are making the pest...

  11. To duckweeds (Landoltia punctata), nanoparticulate copper oxide is more inhibitory than the soluble copper in the bulk solution

    International Nuclear Information System (INIS)

    CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer-Emmett-Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L-1 soluble copper or by 1.0 mg L-1 CuO-NP that released only 0.16 mg L-1 soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 mg L-1 CuO-NP, but not in the comparable 0.2 mg L-1 soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content. - Highlights: ? Lemna growth is reduced by either Cu ions or CuO-NP releasing much less soluble Cu. ? Chlorophyll decreased in plants stressed by CuO-NP but not comparable soluble Cu. ? CuO-NP exposure gives fronds four times more Cu than a similar soluble Cu dose. ? Plant Cu uptake from CuO-NP can explain decreased growth and chlorophyll. - The large uptake of Cu from nanoparticulate CuO suspension into duckweed tissue causes the toxicity of CuO-NP to be equivalent to about four times the soluble Cu in the NP suspension.

  12. To duckweeds (Landoltia punctata), nanoparticulate copper oxide is more inhibitory than the soluble copper in the bulk solution

    Energy Technology Data Exchange (ETDEWEB)

    Shi Jiyan, E-mail: jiyanshi@gmail.com [Department of Land, Air, and Water Resources, University of California, Davis, CA 95616 (United States); Department of Environmental Engineering, Zhejiang University, HangZhou 310029 (China); Abid, Aamir D., E-mail: abid.aamir@gmail.com [Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA 95616 (United States); Kennedy, Ian M., E-mail: kennedyim@mac.com [Department of Mechanical and Aeronautical Engineering, University of California, Davis, CA 95616 (United States); Hristova, Krassimira R., E-mail: krassimira.hristova@marquette.edu [Department of Land, Air, and Water Resources, University of California, Davis, CA 95616 (United States); Department of Biological Sciences, Marquette University, Milwaukee, WI 53233 (United States); Silk, Wendy K., E-mail: wksilk@ucdavis.edu [Department of Land, Air, and Water Resources, University of California, Davis, CA 95616 (United States)

    2011-05-15

    CuO nanoparticles (CuO-NP) were synthesized in a hydrogen diffusion flame. Particle size and morphology were characterized using scanning mobility particle sizing, Brunauer-Emmett-Teller analysis, dynamic light scattering, and transmission electron microscopy. The solubility of CuO-NP varied with both pH and presence of other ions. CuO-NP and comparable doses of soluble Cu were applied to duckweeds, Landoltia punctata. Growth was inhibited 50% by either 0.6 mg L{sup -1} soluble copper or by 1.0 mg L{sup -1} CuO-NP that released only 0.16 mg L{sup -1} soluble Cu into growth medium. A significant decrease of chlorophyll was observed in plants stressed by 1.0 mg L{sup -1} CuO-NP, but not in the comparable 0.2 mg L{sup -1} soluble Cu treatment. The Cu content of fronds exposed to CuO-NP is four times higher than in fronds exposed to an equivalent dose of soluble copper, and this is enough to explain the inhibitory effects on growth and chlorophyll content. - Highlights: > Lemna growth is reduced by either Cu ions or CuO-NP releasing much less soluble Cu. > Chlorophyll decreased in plants stressed by CuO-NP but not comparable soluble Cu. > CuO-NP exposure gives fronds four times more Cu than a similar soluble Cu dose. > Plant Cu uptake from CuO-NP can explain decreased growth and chlorophyll. - The large uptake of Cu from nanoparticulate CuO suspension into duckweed tissue causes the toxicity of CuO-NP to be equivalent to about four times the soluble Cu in the NP suspension.

  13. Characterization and epidemiology of outbreaks of Impatiens necrotic spot virus on lettuce in coastal California

    Science.gov (United States)

    Beginning in 2006, outbreaks of diseases caused by tospoviruses in lettuce have occurred in California with greater frequency. Lettuce in the coastal region has been affected primarily by Impatiens necrotic spot virus (INSV), though Tomato spotted wilt virus (TSWV) was also present. In contrast, TSW...

  14. Development of rapid pathogenicity assay for Verticillium dahliae using early flowering lettuce.

    Science.gov (United States)

    Conventional assays of Verticillium wilt on lettuce require approximately three months from the time of seeding. A reduction in time required for analyses of symptom development would be useful in studies of the Verticillium dahliae-lettuce interaction. In this study, a growth chamber assay was ev...

  15. Antimicrobial activity of cinnamaldehyde and sporan against enteric pathogens on iceberg lettuce

    Science.gov (United States)

    Cinnamaldehyde and sporan alone or in combination with acetic acid (20%) were evaluated for their antimicrobial effects against E. coli O157:H7 and Salmonella on lettuce. Iceberg lettuce leaves were cut into pieces (2 x 3 cm) and inoculated with 50 µL (5 droplets of 10µl) cocktail of five strains o...

  16. The mechanism of ethanol treatment on inhibiting lettuce enzymatic browning and microbial growth

    Science.gov (United States)

    Tissue browning of fresh-cut lettuce greatly affects its quality and consumers’ appreciation. This study investigated the effects of ethanol treatment on enzymatic browning and natural microflora growth of lettuce stem discs. After treated with 20% ethanol for 2 min and then drained by a spinner, le...

  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. SENSORIAL AND CHEMICAL QUALITY OF GAMMA IRRADIATED FRESH-CUT ICEBERG LETTUCE IN MODIFIED ATMOSPHERE PACKAGES

    Science.gov (United States)

    A study was conducted to investigate the upper dose limit of irradiation on quality of fresh-cut iceberg lettuce. Fresh-cut iceberg lettuce packaged in breathable film bags was exposed to 0, 1, 2, 3 or 4 kGy gamma radiation and stored at 3 degree C for 14 days. Carbon dioxide levels were higher and...

  19. Quality of Iceberg and Romaine lettuce treated by combinations of sanitizer, surfactant, and ultrasound

    Science.gov (United States)

    We report an investigation of the individual and combined effects of sonication, two sanitizers (chlorine and Tsunami 100®) and a surfactant (sodium dodecyl sulfate (SDS) on the quality of fresh-cut Iceberg and Romaine lettuce. Lettuce samples were treated for 1 minute with and without ultrasound in...

  20. Quality of gamma ray-irradiated iceberg lettuce and treatments to minimize irradiation-induced disorders

    Science.gov (United States)

    Irradiation of Iceberg lettuce was recently approved by the FDA to enhance microbial safety and to extend shelf-life at doses up to 4 kGy. However, the radiation tolerance of whole head lettuce is unclear. The present study was conducted to investigate the effects of irradiation on the quality of he...

  1. Antioxidant capacity and contents of phenols, ascorbic acid, ?-carotene and lycopene in lettuce

    Directory of Open Access Journals (Sweden)

    Zdravkovi? 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

  2. Occurrence of Cryptosporidium spp. oocysts in low quality water and on vegetables irrigated with low quality water in Kumasi, Ghana

    OpenAIRE

    Petersen, Tobias B; Petersen, Heidi H.; Robert C. Abaidoo; Enemark, Heidi; Dalsgaard, Anders

    2014-01-01

    Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period September – October 2013, with weekly intervals from six sample site...

  3. Effect of temperature and type of packages on quality of stored lettuce

    Directory of Open Access Journals (Sweden)

    Józef B?kowski

    2013-12-01

    Full Text Available Lettuce head cv. Sanora non-wrapped, wrapped with perforated PE film, unperforated PE film, and in stretch film was stored at different temperatures: 1, 6, 20 and 28°C. The lettuce can be stored at 1°C up to 10 days, and at 6°C during 8 days period. Longer storage time caused clear loses of lettuce quality. During first two - three days of storage in both temperatures 1 and 6°C loses of ascorbic acid, dry matter, colour and organoleptic value were not observed. Faster decrease of ascorbic acid content was noted in leuuce stored in unperforated PE film and stretch film, in comparison to perforated PE film. The highest lettuce quality were found in case where lettuce were stored in perforated PE bags at 1°C.

  4. Growth and gas exchange by lettuce stands in a closed, controlled environment.

    Science.gov (United States)

    Wheeler, R M; Mackowiak, C L; Sager, J C; Yorio, N C; Knott, W M; Berry, W L

    1994-05-01

    Two studies were conducted in which 'Waldmann's Green' lettuce (Lactuca sativa L.) was grown hydroponically from seed to harvest in a large (20-m2), atmospherically closed growth chamber for the National Aeronautics and Space Administration's controlled ecological life support system (CELSS) program. The first study used metal-halide (MH) lamps [280 micromoles m-2 s-1 photosynthetic photon flux (PPF)], whereas the second used high-pressure sodium (HPS) lamps (293 micromoles m-2 s-1). Both studies used a 16-hour photoperiod, a constant air temperature (22 to 23C), and 1000 micromoles mol-1 CO2 during the light period. In each study, canopy photosynthesis and evapotranspiration (ET) rates were highly correlated to canopy cover, with absolute rates peaking at harvest (28 days after planting ) at 17 micromoles CO2/m2 per sec and 4 liters m-2 day-1, respectively. When normalized for actual canopy cover, photosynthesis and ET rates per unit canopy area decreased with age (between 15 and 28 days after planting). Canopy cover increased earlier during the study with HPS lamps, and final shoot yields averaged 183 g fresh mass (FM)/plant 8.8 g dry mass (DM)/plant. Shoot yields in the first study with MH lamps averaged 129 g FM/plant and 6.8 g DM/plant. Analysis of leaf tissue showed that ash levels from both studies averaged 22% and K levels ranged from 15% to 17% of tissue DM. Results suggest that lettuce should be easily adaptable to a CELSS with moderate lighting and that plant spacing or transplant schemes are needed to maximize canopy light interception and sustained efficient CO2 removal and water production. PMID:11538197

  5. Comparison of chlorine and peroxyacetic-based disinfectant to inactivate Feline calicivirus, Murine norovirus and Hepatitis A virus on lettuce.

    Science.gov (United States)

    Fraisse, Audrey; Temmam, Sarah; Deboosere, Nathalie; Guillier, Laurent; Delobel, Alexandre; Maris, Pierre; Vialette, Michèle; Morin, Thierry; Perelle, Sylvie

    2011-11-15

    In recent years, raw fruits and vegetables have frequently been involved in foodborne transmission to humans of enteric viruses, particularly noroviruses and hepatitis A virus (HAV). Although viral contamination can occur during all steps of food processing, primary production is a critical stage on which prevention measures must be focused to minimize the risk of infection to consumers. Postharvest sanitation may be a valid technological solution for decreasing the bacterial load on fresh raw material, but there is a lack of data concerning the effectiveness of this process on enteric viruses. In this study, we compared the survival of two human norovirus surrogates, the feline calicivirus (FCV), and the murine norovirus (MNV-1), and of HAV on lettuce after water washing with bubbles and with or without ultrasound, and washing with bubbles in the presence of active chlorine (15 ppm) or peroxyacetic acid-based disinfectant (100 ppm). Cell culture and quantitative RT-PCR assays were used to detect and quantify the viruses on the surface of the lettuce after the sanitizing treatments. Levels of viral inactivation on the lettuce leaves were not significantly different between washing with bubbles and washing with bubbles plus ultrasound and were not dependant on the quantification method. A simple washing without disinfectant resulted in a decrease of approximately 0.7 log units in the quantity of virus detected for HAV and FCV and of 1.0 log unit for MNV-1. In the experimental set-up including a washing step (with or without ultrasound) followed by washing for 2 min in the presence of disinfectants, 15 ppm of active chlorine was found more effective for inactivating FCV (2.9 log units) than HAV and MNV-1 (1.9 log units and 1.4 log units, respectively) whereas 100 ppm of peroxyacetic-based biocide was found effective for inactivating FCV (3.2 log units) and MNV-1 (2.3 log units), but not HAV (0.7 log units). Quantitative RT-PCR results indicated that the presence of viral RNA did not correlate with the presence of infectious viruses on disinfected lettuce, except for MNV-1 processed with chlorine (15 ppm). In comparison with water washing, a substantial additional decrease of genomic FCV titer (1.1 log units) but no significant reduction of the genomic titers of HAV and MNV-1 were found on lettuce treated with chlorine (15 ppm). No significant effect of the disinfection step of lettuce with peroxyacetic-based biocide (100 ppm peracetic acid) was found by qRT-PCR on all genomic viral titers tested. This study illustrates the necessity of determining the effectiveness of technological processes against enteric viruses, using a relevant reference such as HAV, in order to reduce the risk of hepatitis and gastroenteritis by exposure to vegetables. PMID:21924791

  6. Oil palm waste and synthetic zeolite: an alternative soil-less growth substrate for lettuce production as a waste management practice

    Energy Technology Data Exchange (ETDEWEB)

    Jayasinghe, G.Y.; Tokashiki, Y.; Kitou, M.; Kinjo, K. [Kagoshima University, Kagoshima (Japan). United Graduate School of Agricultural Science

    2008-12-15

    A study was conducted to assess the characteristics and the prospective utilization of oil palm waste (OP) and synthetic zeolite (SZ) developed by coal fly ash, as an alternative substrate to peat and commercial perlite for lettuce (Lactuca sativa L.) production. The SZ, OP, sphagnum peat (PE), perlite (PL) and two different SZ-OP mixtures (v/v) at the ratio of 1 : 3 and 1 : 10 were utilized as the substrates under this study. The substrates formulated by mixing SZ with OP at the ratio of 1 : 3 and 1 : 10 showed improved substrate physical and chemical properties such as air space, bulk density, particle density, water-holding capacity, pH and electrical conductivity (EC), which were in the ideal substrate range when compared with PL. Furthermore, the water-holding capacity of the substrate having a 1 : 10 mixing ratio of SZ with OP was higher than that of the PL by 28.23%, whereas the bulk density was lower than that of PL by 35%. A greenhouse experiment was carried out to assess the influence of the substrates on the growth and development of lettuce. The results of the study suggest that the SZ-OP-based substrates and OP can be successfully utilized as alternatives to the commercial perlite and to substitute the conventional peat substrate for lettuce cultivation. In addition, this can be proposed as an alternative waste management practice.

  7. Linear Programming Application to Utilization of Duckweed (Lemna paucicostata) in Least-cost Ration Formulation for Broiler Finisher

    OpenAIRE

    Olorunfemi, Temitope O.S.

    2006-01-01

    This study was on the application of linear programming to the utilization of locally available and non-conventional feedstuff - Duckweed (Lemna paucicostata) as dietary component of feed for broilers aged from 6 to 10 weeks old. Linear Programming (LP) technique was used to investigate, analyse and determine the most efficient way of compounding the least-cost ration. Mathematical models were constructed, taking into consideration nutrient composition of each of the available ingredient, raw...

  8. Utilization of Duckweed (Lemna paucicostata) in Least-cost Feed Formulation for Broiler Starter: A Linear Programming Analysis

    OpenAIRE

    T.O.S. Olorunfemi; F.M. Aderibigbe; Alese, B. K.; E.A. Fasakin

    2006-01-01

    This study was on the economic use of locally available and non-conventional feedstuff - Duckweed (Lemna paucicostata) as dietary component of feed for broilers aged between 0 and 5 weeks old using Linear Programming (LP) technique to investigate, analyse and determine the most efficient way of compounding the least-cost ration. Mathematical models were constructed, taking into consideration nutrient composition of each of the available ingredient, raw material specifications, costs and nutri...

  9. TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

    OpenAIRE

    Julián Andrés Rengifo-Herrera; Cesar Pulgarin; Fiderman Machuca; Janeth Sanabria

    2010-01-01

    In this work, TiO2 photocatalysis was used to disinfect domestic wastewaters previously treated by different biological treatment systems: Upward-flow Anaerobic Sludge Blanket (UASB), facultative pond, and duckweed pond. The microorganisms monitored were E. coli, total coliforms, Shigella species, and Salmonella species. Photocatalytic experiments were carried out using two light sources: a solar simulator (UV intensity: 68-70 W m-2) and black-light lamps (BLL UV intensity: 17-20 W m-2). Samp...

  10. Occurence of Cryptosporidium spp. in low quality water and on vegetables in Kumasi, Ghana

    OpenAIRE

    Petersen, T. B.; Petersen, H. H.; R.C. Abaidoo; Enemark, Heidi; Dalsgaard, A. D.

    2014-01-01

    Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period of, September – October 2013, with weekly intervals from six sample ...

  11. On the variability of plant bio-concentration factors (BCF) of environmental radionuclides. A case study on the effects of surface film and free space on the interpretation of 99mTcO4- sorption in duckweed

    International Nuclear Information System (INIS)

    The present paper addresses plant bioaccumulation factor (BCF) variability, and specifically focuses attention upon the handling of duckweed (Lemna gibba) material, sampled from experimental media, especially considering accumulation/kinetic studies with 99mTcO4-. In these short-term studies, relatively small BCF-values may be encountered, with related interferences in its assessment due to the presence of 99mTcO4- in the surface film medium (SF) and in the cellular water free spaces (FS). The sample handling methods used to remove the SF+FS component of the accumulated 99mTcO4- consisted of blotting, centrifugation and rinsing. The three methods were investigated using d-[1-14C]mannitol, 42K+, 82Br- and 99mTcO4- radioisotopes, which were measured by - and ?-spectrometry, in both solution and solid samples. Centrifugation seems the most promising method to remove SF+FS 99mTcO4-. Results based on both mass analysis and radioactivity determinations in centrifugated fluids are independent of applied concentrations (10-11 to 10-3 mol m-3 99mTcO4-), and are invariably compatible with the conceptual idea of the FS as a free-entrance phase for solutes. Blotting results in an overestimation of BCF values (up to factor 3 for the 99mTcO4- experiments performed), probably due to the incomplete removal of the SF+FS, and is suggested to yield irregular results, leading to high variances in BCF values obtained. The application of an efflux/rinsing period is indicated to result in an underestimation of BCF values (up to factor 10 for the 99mTcO4- experiments performed), probably due to excess removal of (non-SF+FS) components of accumulated solutes. Here we advocate centrifugation as a routine sample handling method to avoid SF+FS interferences in short-term (kinetic) 99mTcO4- uptake studies in duckweed. Moreover, the results suggest a more general applicability of centrifugation as a sample handling method to avoid SF+FS interferences in short-term element accumulation studies; centrifugation approaches should, however, be adjusted to plant cell characteristics

  12. On the variability of plant bio-concentration factors (BCF) of environmental radionuclides. A case study on the effects of surface film and free space on the interpretation of 99mTcO{sub 4}{sup -} sorption in duckweed

    Energy Technology Data Exchange (ETDEWEB)

    Wolterbeek, H.T.; Van der Meer, A.J.G.M.; Dielemans, U. [Department of Radiochemistry, Delft University of Technology, Interfaculty Reactor Institute, Nuclear Environmental Studies, Mekelweg 15, 2629 JB Delft (Netherlands)

    2000-08-10

    The present paper addresses plant bioaccumulation factor (BCF) variability, and specifically focuses attention upon the handling of duckweed (Lemna gibba) material, sampled from experimental media, especially considering accumulation/kinetic studies with 99mTcO{sub 4}{sup -}. In these short-term studies, relatively small BCF-values may be encountered, with related interferences in its assessment due to the presence of 99mTcO{sub 4}{sup -} in the surface film medium (SF) and in the cellular water free spaces (FS). The sample handling methods used to remove the SF+FS component of the accumulated 99mTcO{sub 4}{sup -} consisted of blotting, centrifugation and rinsing. The three methods were investigated using d-[1-{sup 14}C]mannitol, 42K{sup +}, 82Br{sup -} and 99mTcO{sub 4}{sup -} radioisotopes, which were measured by - and {gamma}-spectrometry, in both solution and solid samples. Centrifugation seems the most promising method to remove SF+FS 99mTcO{sub 4}{sup -}. Results based on both mass analysis and radioactivity determinations in centrifugated fluids are independent of applied concentrations (10{sup -11} to 10{sup -3} mol m{sup -3} 99mTcO{sub 4}{sup -}), and are invariably compatible with the conceptual idea of the FS as a free-entrance phase for solutes. Blotting results in an overestimation of BCF values (up to factor 3 for the 99mTcO{sub 4}{sup -} experiments performed), probably due to the incomplete removal of the SF+FS, and is suggested to yield irregular results, leading to high variances in BCF values obtained. The application of an efflux/rinsing period is indicated to result in an underestimation of BCF values (up to factor 10 for the 99mTcO{sub 4}{sup -} experiments performed), probably due to excess removal of (non-SF+FS) components of accumulated solutes. Here we advocate centrifugation as a routine sample handling method to avoid SF+FS interferences in short-term (kinetic) 99mTcO{sub 4}{sup -} uptake studies in duckweed. Moreover, the results suggest a more general applicability of centrifugation as a sample handling method to avoid SF+FS interferences in short-term element accumulation studies; centrifugation approaches should, however, be adjusted to plant cell characteristics.

  13. Accumulation of {sup 99}Tc in duckweed Lemna minor L. as a function of growth rate and {sup 99}Tc concentration

    Energy Technology Data Exchange (ETDEWEB)

    Hattink, J. E-mail: jhattink@hotmail.com; Wolterbeek, H.Th

    2001-07-01

    This study focuses on the question of whether short-term studies can be used to forecast the accumulation of the long-lived fission product {sup 99}Tc in duckweed, Lemna minor L., grown in the field; in other words, are the accumulation parameters independent of changing growth rates typical of natural populations of duckweed. Two processes determine the {sup 99}Tc accumulation: (i) uptake and release of {sup 99}TcO{sub 4}{sup -}, characterised by a concentration factor, K{sub d}, and (ii) first-order reduction and complexation of Tc{sup VII}, characterised by k{sub red}. At various {sup 99}Tc concentrations, the growth, total Tc and TcO{sub 4}{sup -} accumulation were monitored over 10 days; parameters were fitted and compared with earlier results. Both K{sub d} and k{sub red} turn out to be independent of time, concentration and growth rate up to a concentration of 10{sup -6} mol l{sup -1} {sup 99}TcO{sub 4}{sup -}. Concentrations above this level result in toxic effects. The Tc accumulation in field populations of duckweed at Tc concentrations which generally occur in the environment can be forecasted by using the results from short-term experiments.

  14. Darwin-Wallace Demons: survival of the fastest in populations of duckweeds and the evolutionary history of an enigmatic group of angiosperms.

    Science.gov (United States)

    Kutschera, U; Niklas, K J

    2015-01-01

    In evolutionary biology, the term 'Darwinian fitness' refers to the lifetime reproductive success of an individual within a population of conspecifics. The idea of a 'Darwinian Demon' emerged from this concept and is defined here as an organism that commences reproduction almost immediately after birth, has a maximum fitness, and lives forever. It has been argued that duckweeds (sub-family Lemnoideae, order Alismatales), a group containing five genera and 34 species of small aquatic monocotyledonous plants with a reduced body plan, can be interpreted as examples of 'Darwinian Demons'. Here we focus on the species Spirodela polyrhiza (Great duckweed) and show that these miniaturised aquatic angiosperms display features that fit the definition of the hypothetical organism that we will call a 'Darwin-Wallace Demon' in recognition of the duel proponents of evolution by natural selection. A quantitative analysis (log-log bivariate plot of annual growth in dry biomass versus standing dry body mass of various green algae and land plants) revealed that duckweeds are thus far the most rapidly growing angiosperms in proportion to their body mass. In light of this finding, we discuss the disposable soma and metabolic optimising theories, summarise evidence for and against the proposition that the Lemnoideae (family Araceae) reflect an example of reductive evolution, and argue that, under real-world conditions (environmental constraints and other limitations), 'Darwin-Wallace Demons' cannot exist, although the concept remains useful in much the same way that the Hardy-Weinberg law does. PMID:24674028

  15. Responses of antioxidant systems after exposition to rare earths and their role in chilling stress in common duckweed (Lemna minor L.): a defensive weapon or a boomerang?

    Science.gov (United States)

    Ippolito, M P; Fasciano, C; d'Aquino, L; Morgana, M; Tommasi, F

    2010-01-01

    Extensive agriculture application of rare earth elements (REEs) in Far East countries might cause spreading of these metals in aquatic and terrestrial ecosystems, thus inducing a growing concern about their environmental impact. In this work the effects of a mix of different REE nitrate (RE) and of lanthanum nitrate (LA) on catalase and antioxidant systems involved in the ascorbate-glutathione cycle were investigated in common duckweed Lemna minor L. The results indicated that L. minor shows an overall good tolerance to the presence of REEs in the media. Treatments at concentrations up to 5 mM RE and 5 mM LA did not cause either visible symptoms on plants or significant effects on reactive oxygen species (ROS) production, chlorophyll content, and lipid peroxidation. Toxic effects were observed after 5 days of exposition to 10 mM RE and 10 mM LA. A remarkable increase in glutathione content as well as in enzymatic antioxidants was observed before the appearance of the stress symptoms in treated plants. Duckweed plants pretreated with RE and LA were also exposed to chilling stress to verify whether antioxidants variations induced by RE and LA improve plant resistance to the chilling stress. In pretreated plants, a decrease in ascorbate and glutathione redox state and in chlorophyll content and an increase in lipid peroxidation and ROS production levels were observed. The use of antioxidant levels as a stress marker for monitoring REE toxicity in aquatic ecosystems by means of common duckweed is discussed. PMID:19504227

  16. Identification of new Bremia lactucae races in lettuce in São Paulo state Identificação de novas raças de Bremia lactucae em alface no estado de São Paulo

    OpenAIRE

    Renata Castoldi; Hamilton César de O Charlo; Tagli Dalpian; Danilo M Melo; Adelita P Botelho; Leila T. Braz

    2012-01-01

    Lettuce is the most consumed leafy vegetable in Brazil. However, its production has faced increasing difficulties mainly due to the infestation of producing areas with Bremia lactucae, the causing agent of downy mildew, the worst disease in lettuce. The aim of this study was to identify B. lactucae races occurring in lettuce producing areas of São Paulo state, during 2008 and 2009. Lettuce leaf samples containing B. lactucae sporangia were collected in the major lettuce producing areas of São...

  17. Comparative study on chemical pretreatments to accelerate enzymatic hydrolysis of aquatic macrophyte biomass used in water purification processes.

    Science.gov (United States)

    Mishima, D; Tateda, M; Ike, M; Fujita, M

    2006-11-01

    In this study, enzymatic hydrolysis of two floating aquatic plants which are suitable for water purification, water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.), was performed to produce sugars. Twenty chemical pretreatments were comparatively examined in order to improve the efficiency of enzymatic hydrolysis. As a result, the alkaline/oxidative (A/O) pretreatment, in which sodium hydroxide and hydrogen peroxide were used, was the most effective pretreatment in terms of improving enzymatic hydrolysis of the leaves of water hyacinth and water lettuce. The amount of reducing sugars in enzymatic hydrolysate of water lettuce leaves was 1.8 times higher than that of water hyacinth leaves, therefore water lettuce seems to be more attractive as a biomass resource than water hyacinth. Although roots of these plants contained large amounts of polysaccharides such as cellulose and hemicellulose, they generated less monosaccharides than from leaves, no matter which chemical pretreatment was tested. PMID:16309902

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

    Science.gov (United States)

    Markland, S M; Shortlidge, K L; Hoover, D G; Yaron, S; Patel, J; Singh, A; Sharma, M; Kniel, K E

    2013-12-01

    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 substrate using drip and overhead irrigation. When overhead inoculated with 7 log CFU/ml of each strain, E. coli populations were significantly (P = 0.03) higher on overhead-irrigated plants than on drip-irrigated plants. APECstx-, E. coli O104:H4 and APECstx+ populations were recovered on plants at 3.6, 2.3 and 3.1 log CFU/g at 10 dpi (days post-inoculation), respectively. E. coli O157:H7 was not detected on basil after 4 dpi. The persistence of E. coli O157:H7 and APECstx- were similar when co-inoculated on lettuce and spinach plants. On spinach and lettuce, E. coli O157:H7 and APEC populations declined from 5.7 to 6.1 log CFU/g and 4.5 log CFU/g, to undetectable at 3 dpi and 0.6-1.6 log CFU/g at 7 dpi, respectively. The detection of low populations of APEC and E. coli O104:H4 strains 10 dpi indicates these strains may be more adapted to environmental conditions than E. coli O157:H7. This is the first reported study of E. coli O104:H4 on a produce commodity. PMID:23280331

  19. Phytotoxic action of naphthoquinone juglone demonstrated on lettuce seedling roots.

    Science.gov (United States)

    Babula, Petr; Vaverkova, Veronika; Poborilova, Zuzana; Ballova, Ludmila; Masarik, Michal; Provaznik, Ivo

    2014-11-01

    Juglone, 5-hydroxy-1,4-naphthoquinone, is the plant secondary metabolite with allelopathic properties, which was isolated especially from the plant species belonging to family Juglandaceae A. Rich. ex Kunth (walnut family). The mechanism of phytotoxic action of juglone was investigated on lettuce seedlings Lactuca sativa L. var. capitata L. cv. Merkurion by determining its effect at different levels. We have found that juglone inhibits mitosis (mitotic index 8.5 ± 0.6% for control versus 2.2 ± 0.9% for 250 ?M juglone), changes mitotic phase index with accumulation of the cells in prophase (56.5 ± 2.6% for control versus 85.3 ± 5.0% for 250 ?M juglone), and decreases meristematic activity in lettuce root tips (51.07 ± 3.62% for control versus 5.27 ± 2.29% for 250 ?M juglone). In addition, juglone induced creation of reactive oxygen species and changed levels of reactive nitrogen species. Amount of malondialdehyde, a product of lipid peroxidation, increased from 24.0 ± 4.0 ng g(-1) FW for control to 55.5 ± 5.4 ng g(-1) FW for 250 ?M juglone. We observed also changes in cellular structure, especially changes in the morphology of endoplasmic reticulum. Reactive oxygen species induced damage of plasma membrane. All these changes resulted in the disruption of the mitochondrial membrane potential, increase in free intracellular calcium ions, and DNA fragmentation and programmed cell death that was revealed by two methods, TUNEL test and DNA electrophoresis. The portion of TUNEL-positive cells increase from 0.96 ± 0.5% for control to 7.66 ± 1.5% for 250 ?M juglone. Results of the study indicate complex mechanism of phytotoxic effect of juglone in lettuce root tips and may indicate mechanism of allelopathic activity of this compound. PMID:25240266

  20. Exposure studies of core-shell Fe/Fe(3)O(4) and Cu/CuO NPs to lettuce (Lactuca sativa) plants: Are they a potential physiological and nutritional hazard?

    Science.gov (United States)

    Trujillo-Reyes, J; Majumdar, S; Botez, C E; Peralta-Videa, J R; Gardea-Torresdey, J L

    2014-02-28

    Iron and copper nanomaterials are widely used in environmental remediation and agriculture. However, their effects on physiological parameters and nutritional quality of terrestrial plants such as lettuce (Lactuca sativa) are still unknown. In this research, 18-day-old hydroponically grown lettuce seedlings were treated for 15 days with core-shell nanoscale materials (Fe/Fe(3)O(4), Cu/CuO) at 10 and 20mg/L, and FeSO(4)·7H(2)O and CuSO(4)·5H(2)O at 10mg/L. At harvest, Fe, Cu, micro and macronutrients were determined by ICP-OES. Also, we evaluated chlorophyll content, plant growth, and catalase (CAT) and ascorbate peroxidase (APX) activities. Our results showed that iron ions/NPs did not affect the physiological parameters with respect to water control. Conversely, Cu ions/NPs reduced water content, root length, and dry biomass of the lettuce plants. ICP-OES results showed that nano-Cu/CuO treatments produced significant accumulation of Cu in roots compared to the CuSO(4)·5H(2)O treatment. In roots, all Cu treatments increased CAT activity but decreased APX activity. In addition, relative to the control, nano-Cu/CuO altered the nutritional quality of lettuce, since the treated plants had significantly more Cu, Al and S but less Mn, P, Ca, and Mg. PMID:24462971

  1. Effect of the Municipal Garbage on the Growth of Lettuce

    OpenAIRE

    K.N. Al-Redhaiman; I.N. Nassar; I.S. Al-Salamah

    2003-01-01

    Municipal Garbage (MG) as a plant nutrient supply was evaluated. Some of the garbage was collected from Hail city, Kingdom of Saudi Arabia. The garbage was fermented partially after removing its contents of stones and metals. Lettuce plants were transplanted in five greenhouse pot experiments. In the first, a portion of the MG was mixed with a sandy soil at either 1, 2 or 3% before the transplanting. In the second, a portion of the MG was mixed with hydrochloric acid 0.1 Nat ratio of 1:2 for ...

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

    International Nuclear Information System (INIS)

    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)

  3. Manure- and Biosolids-Resident Murine Norovirus 1 Attachment to and Internalization by Romaine Lettuce?

    Science.gov (United States)

    Wei, Jie; Jin, Yan; Sims, Tom; Kniel, Kalmia E.

    2010-01-01

    The attachment of murine norovirus 1 (MNV) in biosolids, swine manure, and dairy manure to Romaine lettuce and internalization of this virus were evaluated. The MNV in animal manures had behavior similar to that of pure MNV; however, MNV in biosolids had significantly higher levels of attachment and internalization than pure MNV or MNV in manures. The incubation time did not affect the attachment of MNV in biosolids or manure. Confocal microscopy was used to observe MNV on lettuce after SYBR gold-labeled MNV was added directly to lettuce or after lettuce was submersed in labeled virus. MNV was observed on the lettuce surface, inside open cuts, and occasionally within stomata. In general, lettuce pieces with a long cut on the edge and short cuts on the stem was more likely to contain internalized MNV than intact lettuce pieces, as observed by confocal microscopy; however, while the difference was visible, it was not statistically significant. This study showed that the presence of MNV in biosolids may increase the risk of fresh produce contamination and that the MNV in open cuts and stomata is likely to be protected from sanitization. PMID:19933344

  4. Effect of nutrient solution on growth and some physiological characters of hydroponically grown lettuce

    Directory of Open Access Journals (Sweden)

    M. Safaei

    2014-07-01

    Full Text Available   Lettuce is one of the major leafy vegetables that is consumed as fresh and salads crops. Although, today, the tendency is to grow lettuce as hydroponic crop, there is not an optimal nutrient solution and growers use different nutrient solutions for growing lettuce. Therefore, an experiment was conducted to find an optimal nutrient solution to grow lettuce. In this experiment, the effect of various important nutrient solutions including, NSHog, NSKnop, NSUK, and NSU.T on two cultivars of lettuce (Siahoo and Conquistador was investigated. The experiment was arranged in the randomized completely block design with four replicates and traits i.e., chlorophyll index, photosynthetic efficiency, tip burn, fresh and dry weight, leaf area, and number of edible leaves were assessed. Plants were sown in the media containing perlite and then irrigated with nutrient solution manually. The results showed that nutrient solution had significant effect on the yield and some of the growth characteristic of lettuce. Plants grown in the UK solution had the highest fresh and dry mass, leaf area, and the number of edible leaves. The lowest fresh and dry weight, leaf area and the number of edible leaves was obtained in plants supplied with UT solution. Results also showed significant variation between two cultivars. Siahoo had higher fresh weight, leaf area, and the number of edible leaves than conquistador. Interaction between cultivar and nutrient solution had significant effect on chlorophyll index. According to the results obtained, UK nutrient solution was the best nutrient solution for lettuce production.

  5. Effect of Different Calcium Concentration in Contaminate Soil on 90S Accumulation by the Seasonal Vegetative Growth of Lettuce

    International Nuclear Information System (INIS)

    Pot experiment was conducted in greenhouse at National Center for Agriculture Research and Technology Transfer (NCARTT) farm in Baqa. To establish the effect of different calcium concentration in the contaminated soil on the 90S accumulation by the seasonal vegetative growth of lettuce. The pots were distributed in split plot in RCBD design with four replicates. The main plots of experiment were four concentration of calcium (Ca++) in the soil. The calcium soluble solution was applied and mixed with the soil. Four concentrations of calcium were 50, 100, 150 and 200 mg Ca /Kg. The sub main plots of experiment were four specific activities of Strontium-90. The contamination has been done with 90S to the surface area of the soil after one week of planting. The specific activities of 90S were: 40, 57, 73 and 89 Bq/Kg soil . The results indicate after 70 days of planting (duration of season), that the specific active of 90Sr in vegetative mass of plant (Lettuce) and in leached irrigation water at the end of season was nonsignificant increased with the increment of Ca concentration in the soil . The specific active of 90Sr reached to 1.12 Bq/Kg in plant and to 1.13 Bq/ l in irrigation water. There was strong linear correlation between specific active of 90Sr in vegetative mass of plant (Lettuce) with the increment of Ca concentration in the soil (r2= 94) , the similar results was observed for irrigation water (r2=88) . The distribution of specific active of 90Sr in the soil, plant and irrigation water was not significant effected by the increasing of specific active of 90Sr in contaminated soil and / or by increasing of Ca concentration in the soil. It was found that most of specific active of 90Sr in all treatments were remained at the end of season in the soil (96.6-97.9%). The values of Stander Transfer Factor (TFs) for 90Sr by plant or irrigation water weren't effected with increasing of specific active of 90Sr in the soil .On contrary the increasing of Ca concentration in the soil effectuate nonsignificant decreased of TFs by plant and irrigation water. The decreased in values of TFs were ranged from 0.010 to 0.018. (authors)

  6. Effect of CO2 levels on nutrient content of lettuce and radish

    Science.gov (United States)

    McKeehen, J. D.; Smart, D. J.; Mackowiak, C. L.; Wheeler, R. M.; Nielsen, S. S.; Mitchell, C. A. (Principal Investigator)

    1996-01-01

    Atmospheric carbon-dioxide enrichment is known to affect the yield of lettuce and radish grown in controlled environments, but little is known about CO2 enrichment effects on the chemical composition of lettuce and radish. These crops are useful model systems for a Controlled Ecological Life-Support System (CELSS), largely because of their relatively short production cycles. Lettuce (Lactuca sativa L.) cultivar 'Waldmann's Green' and radish (Raphanus sativus L.) cultivar 'Giant White Globe' were grown both in the field and in controlled environments, where hydroponic nutrient solution, light, and temperature were regulated, and where CO2 levels were controlled at 400, 1000, 5000, or 10,000 ppm. Plants were harvested at maturity, dried, and analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate N, free sugars, starch, total dietary fiber, and minerals. Total N, protein N, nonprotein N (NPN), and nitrate N generally increased for radish roots and lettuce leaves when grown under growth chamber conditions compared to field conditions. The nitrate-N level of lettuce leaves, as a percentage of total NPN, decreased with increasing levels of CO2 enrichment. The ash content of radish roots and of radish and lettuce leaves decreased with increasing levels of CO2 enrichment. The levels of certain minerals differed between field- and chamber-grown materials, including changes in the calcium (Ca) and phosphorus (P) contents of radish and lettuce leaves, resulting in reduced Ca/P ratio for chamber-grown materials. The free-sugar contents were similar between the field and chamber-grown lettuce leaves, but total dietary fiber content was much higher in the field-grown plant material. The starch content of growth-chamber lettuce increased with CO2 level.

  7. Determination of low levels of perchlorate in lettuce and spinach using ion chromatography-electrospray ionization mass spectrometry (IC-ESI-MS).

    Science.gov (United States)

    Seyfferth, Angelia L; Parker, David R

    2006-03-22

    A sample preparation method was developed to quantify environmentally relevant (low micrograms per liter) concentrations of perchlorate (ClO4(-)) in leafy vegetables using IC-ESI-MS. Lettuce and spinach were macerated, centrifuged, and filtered, and the aqueous extracts were rendered water-clear using a one-step solid-phase extraction method. Total time for extraction and sample preparation was 6 h. Ion suppression was demonstrated and was likely due to unknown organics still present in the extract solution after cleanup. However, this interference was readily eliminated using a Cl(18)O4(-) internal standard at 1 microg/L in all standards and samples. Hydroponically grown perchlorate-free butterhead lettuce was spiked to either 10.3 or 37.7 microg/kg of fresh weight (FW), and recoveries were between 91 and 98% and between 93 and 101%, respectively. Five types of lettuce and spinach from a local grocery store were then analyzed; they contained from 0.6 to 6.4 microg/kg of FW. Spike recoveries using the store-bought samples ranged from 89 to 100%. The method detection limit for perchlorate in plant extracts is 40 ng/L, and the corresponding minimum reporting limit is 200 ng/L or 0.8 microg/kg of FW. PMID:16536569

  8. Fiscalização de hortas produtoras de verduras do município de Ribeirão Preto, SP Monitoring of lettuce crops of Ribeirão Preto, SP, Brazil

    Directory of Open Access Journals (Sweden)

    Osvaldo M. Takayanagui

    2000-04-01

    Full Text Available O consumo de verduras cruas desempenha importante papel na transmissão de várias doenças infecciosas pela freqüente prática de irrigação de hortas com água contaminada. O objetivo deste estudo é a avaliação das condições higiênico-sanitárias de todas as hortas produtoras de verduras de Ribeirão Preto, SP com implantação de um sistema de fiscalização. A análise laboratorial de 129 hortas revelou irregularidades em 20,1% delas, destacando-se elevada concentração de coliformes fecais em 17%, presença de Salmonella em 3,1% e de vários enteroparasitas (Ascaris sp, Ancylostomidae, Strongyloides sp, Hymenolepis nana e Giardia sp em 13,1%. A repetição da análise das hortas irregulares determinou a interdição definitiva de uma delas; todas as demais foram aprovadas, comprovando a eficácia do sistema de fiscalização, particularmente com a implantação, inédita no país, do certificado de vistoria sanitária.The ingesting of raw vegetables plays an important role in the transmission of several infectious diseases due to the high frequency of irrigation with wastewater. The objective of this study was to evaluate the sanitary conditions of all lettuce producing crops in Ribeirão Preto through microbiological and parasitological analysis of both irrigation water and lettuce together with the implantation of an effective crop monitoring. Laboratory analysis of 129 crops showed irregularities in 26 (20.1% of these: high concentration of fecal coliforms in 17% of the lettuce, presence of Salmonella in 3.1% and several enteroparasites (Ascaris sp, Ancylostomidae, Strongyloides sp, Hymenolepis nana, and Giardia sp in 13.1%. Persistent irregularities determined the definitive closing down of one producer; all of the remaining 128 crops were eventually approved, thus demonstrating the efficacy of lettuce crop monitoring. Crops approved in the laboratory analysis were awarded a Sanitary Inspection Certificate - an unprecedented procedure in our Country - that resulted in a better acceptance of the monitoring.

  9. 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.

  10. Biological Control of Sclerotinia sclerotiorum in Lettuce Using Antagonistic Bacteria

    Directory of Open Access Journals (Sweden)

    Bong-Goan Chon

    2013-03-01

    Full Text Available To isolate antagonistic bacteria against sclerotinia rot of lettuce, caused by Sclerotinia sclerotiorum, soil samples were collected from the diseased greenhouse field in Namyangju city, Gyeong-gi province from 2007 to 2008. A total of 196 bacterial isolates were isolated using serial dilution method. In dual culture assay in vitro, 26 isolates showed more than 80% of inhibition rates of mycelial growth of S. sclerotiorum. Based on 16S rDNA sequence analysis, the 26 isolates were identified as Bacillus megaterium, B. cereus, B. subtilis, Arthrobacter nicotianae, A. ramosus, Pseudomonas filiscindens, Stenotrophomonas maltophilia, Brevibacterium frigoritolerans and Sphingobacterium faecium. The 26 isolates inhibited the mycelial growth of S. sclerotiorum up to 80% and the sclerotial germination 0−100%. In the greenhouse pot test of ten isolates conducted in summer, 2 isolates B. megaterium (DK6 and B. cereus (C210 showed control efficacy on sclerotia viability of S. sclerotiorum, 20% and 35%, respectively. In the greenhouse pot test in winter, the disease incidence of the control group was 80%, whereas those of 9 isolates among 26 were approximately 20%. From the result, the 9 isolates are expected as potentially antagonistic bacteria for biological control of sclerotinia rot of lettuce caused by S. sclerotiorum.

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

    DEFF Research Database (Denmark)

    Jensen, Annette Nygaard; Storm, Christina

    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 agricultural fields prior to the planting of lettuce seedlings. At harvest, leaves (25 g) of 10 lettuce heads were pooled into one sample unit (n = 147). Soil samples (100 g) were collected from one field before slurry application and four times during the growth period (n = 75). E. coli was enumerated in slurry, soil, and lettuce on 3M Petrifilm Select E. coli Count Plates containing 16 mg/liter streptomycin, 16 mg/liter ampicillin, or no antimicrobial agent. Selected E. coli isolates (n = 83) originating from the slurry, soil, and lettuce were genotyped by pulsed-field gel electrophoresis (PFGE) to determine the similarity of isolates. The slurry applied to the fields contained 3.0 to 4.5 log CFU/g E. coli. E. coli was found in 36 to 54% of the lettuce samples, streptomycin-resistant E. coli was found in 10.0 to 18.0% of the lettuce samples, and ampicillin-resistant E. coli in 0 to 2.0% of the lettuce samples (the detection limit was 1 log CFU/g). The concentration of E. coli exceeded 2 log CFU/g in 19.0% of the lettuce samples. No E. coli was detected in the soil before the slurry was applied, but after, E. coli was present until the last sampling day (harvest), when 10 of 15 soil samples contained E. 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 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.

  12. Transfer of Metals in Food Chain: An Example with Copper and Lettuce

    Science.gov (United States)

    Vincevica-Gaile, Zane; Klavins, Maris

    2012-12-01

    Present study investigated the possible transfer of metals in the food chain (from soil to edible plants). The experiment was done with lettuce Lactuca sativa grown in different types of soil contaminated with copper (Cu2+) in various concentrations, with or without addition of humic substances. The highest content of copper was detected in lettuce samples grown in soils with lower levels of organic matter, thus indicating the importance of soil organics in metal transfer routes and accumulation rates in plants. It was found that copper accumulation in lettuce grown in contaminated soils can be significantly reduced by the addition of humic substances.

  13. Allelopathic Effects of Shoot and Root Extracts From Three Alien and Native Chenopodiaceae Species on Lettuce Seed Germination

    Directory of Open Access Journals (Sweden)

    Yamina Bouchikh-Boucif

    2014-12-01

    Full Text Available One basic method of improving rangelands in the country is the use of native as well as exotic species of adaptable plants. Some species of Atriplex, like Atriplex canescens and Atriplex nummularia has been introduced in many thousands hectares of rangelands since more than 20 years, it feeds some debates on the algerian scientific community, so that’s why it is important to know the impact and necessary to consider its effects on native species. In the current study the effect of chemical competition of Atriplex canescens and Atriplex nummularia comparing to native Atriplex halimus by observing the effect of aqueous extracts of leaves, stems and roots of the three chenopod species assayed at 0.06, 0.63, 1.55, 3.12 and 6.25 g /l on the germination of lettuce seed test. Seed germination was significantly inhibited by shoot alien species extracts especially A.nummularia at concentrations ranging from 1.55 to 6.26 g/l with decrease rate of 20% in the lettuce seed tests indicating the presence of allelopathic substances, in 0,06 the germination increased to more than 10% comparing to the water irrigated seeds. An opposed effect than the expected had been found because Atriplex canescens had a less allelopathic effect than our native plant Atriplex halimus.

  14. An improved method for transformation of lettuce by Agrobacterium tumefaciens with a gene that confers freezing resistance

    Directory of Open Access Journals (Sweden)

    Pileggi Marcos

    2001-01-01

    Full Text Available An efficient method for constructing transgenic lettuce cultivars by Agrobacterium tumefaciens was described by Torres et al., 1993. In the present work, an improvement of the above procedure is described and applied to transform the cultivar Grand Rapids with a mutated P5CS gene. The major modifications were concerned with turning more practical the transformation and regeneration protocols. Also we tried to improve transformation steps by increasing injured area in explants and prolonging co-cultivation with Agrobacteria (in larger concentration. A more significant selective pressure was used against non-transformed plants and bacteria. In these work we were concerned to obtain T1 and T2 seeds. The P5CS gene codes for a delta¹-pyrroline-5-carboxylate synthetase, a bifunctional enzyme that catalyzes two steps of proline biosynthesis in plants (Zhang et al., 1995; Peng et al., 1996, while the mutated gene is insensitive to feedback inhibition by proline. The potential benefit of this gene is to confer water stress resistance (drought, salt, cold due to increased intracellular levels of proline that works like an osmoprotectant. In this work could obtain and characterize transgenic lettuce lineages which are resistant to freezing temperature.

  15. Assessment of lettuce quality during storage at low relative humidity using Global Stability Index methodology / Avaliação da qualidade da alface durante o armazenamento em baixa umidade relativa usando o Índice Global da Estabilidade

    Scientific Electronic Library Online (English)

    María Roberta, Ansorena; María Victoria, Agüero; María Grabriela, Goñi; Sara, Roura; Alejandra, Ponce; María del Rosario, Moreira; Karina, Di Scala.

    2012-06-01

    Full Text Available Durante a pós-colheita a alface é exposta a condições adversas (baixa umidade relativa) que reduzem a qualidade do vegetal. A fim de avaliar sua vida útil, um grande número de índices de qualidade tem que ser analisado, requerendo um cuidadoso delineamento experimental e um longo consumo de tempo. N [...] este trabalho, o método modificado do Índice Global da Estabilidade foi aplicado para estimar a qualidade da alface manteiga a uma baixa umidade relativa durante o armazenamento diferenciando três zonas (interna, média e externa). Os resultados indicaram que, para a zona externa, os índices mais relevantes foram o conteúdo da umidade relativa, conteúdo da água, ácido ascórbico e a contagem total de micro-organismos mesófilos. Para a zona média, foram conteúdo da umidade relativa, conteúdo da água, clorofila total, ácido ascórbico e, para a interna, conteúdo da umidade relativa, água ligada, conteúdo da água e a contagem total de micro-organismos mesófilos. Foi proposto um modelo matemático entre o Índice Global da Estabilidade e qualidade visual geral para cada zona da alface. Ademais, foi aplicada a distribuição de Weibull para estimar o tempo da vida útil do vegetal, o qual foi: 5, 4 e 3 dias para as zonas interna, média e externa, respectivamente. Quando foi estudado o efeito do tempo de armazenamento para cada zona da alface, todos os índices avaliados na zona externa mostraram diferenças significativas (p Abstract in english During postharvest, lettuce is usually exposed to adverse conditions (e.g. low relative humidity) that reduce the vegetable quality. In order to evaluate its shelf life, a great number of quality attributes must be analyzed, which requires careful experimental design, and it is time consuming. In th [...] is study, the modified Global Stability Index method was applied to estimate the quality of butter lettuce at low relative humidity during storage discriminating three lettuce zones (internal, middle, and external). The results indicated that the most relevant attributes were: the external zone - relative water content, water content , ascorbic acid, and total mesophilic counts; middle zone - relative water content, water content, total chlorophyll, and ascorbic acid; internal zone - relative water content, bound water, water content, and total mesophilic counts. A mathematical model that takes into account the Global Stability Index and overall visual quality for each lettuce zone was proposed. Moreover, the Weibull distribution was applied to estimate the maximum vegetable storage time which was 5, 4, and 3 days for the internal, middle, and external zone, respectively. When analyzing the effect of storage time for each lettuce zone, all the indices evaluated in the external zone of lettuce presented significant differences (p

  16. Occurrence of Cryptosporidium spp. oocysts in low quality water and on vegetables irrigated with low quality water in Kumasi, Ghana

    DEFF Research Database (Denmark)

    Petersen, Tobias Boel; Petersen, Heidi Huus

    Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. Oocysts were stored approx. six weeks at 4C° before enumeration and approx. two weeks on slides at room temperature. Oocysts were subsequently washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3,268 per 10L water and 11 – 118 oocysts per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water samples from both rivers and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

  17. Reúso de águas residuárias da piscicultura e da suinocultura na irrigação da cultura da alface / Reuse of wastewater from swine and fish activities in the lettuce culture

    Scientific Electronic Library Online (English)

    Dirceu, Baumgartner; Silvio C., Sampaio; Tatiana R. da, Silva; Carla R. P. A., Teo; Márcio A., Vilas Boas.

    2007-04-01

    Full Text Available Este trabalho teve o objetivo de avaliar o desenvolvimento, a produção e a qualidade sanitária da cultura da alface irrigada com águas residuárias originadas da suinocultura e da piscicultura. Os tratamentos avaliados foram: T1 - alface irrigada com água de origem subterrânea e adubação suplementar; [...] T2 - alface irrigada com água residuária de viveiro de peixes alimentados com ração; T3 - alface irrigada com água residuária originária de lagoa de estabilização de dejetos de suínos, e T4 - água de lagoa de cultivo de algas, alimentada com resíduo de biodigestor de dejeto de suíno. Os tratamentos não apresentaram diferenças significativas para altura da alface, diâmetro da cabeça, comprimento da raiz, massa da raiz, massa total da planta, massa fresca e massa seca; os tratamentos T4 e T2 apresentaram os maiores valores para comprimento da maior folha e número de folhas, respectivamente; em geral, as análises foliares e a extração de macro e micronutrientes pela cultura não apresentaram diferenças significativas; ocorreu contaminação de coliformes fecais e totais em todos os tratamentos; não ocorreu contaminação de Escherichia coli em todos os tratamentos; todos os Coeficientes de Uniformidade de Christiansen (CUC) encontrados foram acima de 85%, exceto para o tratamento T3 que foi de 74,05%; ocorreram alterações químicas no solo proporcionais às características das águas utilizadas nos respectivos tratamentos. Abstract in english The objective of this work was to evaluate development, production and sanitary quality of the irrigated lettuce with wastewater from fish and swine activities. The evaluated treatments was: T1 - lettuce irrigated with water from underground origin and supplemental fertilization; T2 - lettuce irriga [...] ted with wastewater from fish activities and fish fed with ration; T3 - lettuce irrigated with wastewater from swine treated in stabilization lagoon; and T4 - lettuce irrigated with effluent from seaweed lagoon, fed with wastewater from swine activities treated with anaerobic reactor. The treatments did not present significant differences for next culture characteristics: height, diameter head, length root, mass root, total mass plant, green mass and dry mass; the treatments T4 and T2 presented the biggest values for length and number leaf, respectively; in general, leaf analyses and extraction of macro and micronutrients by culture did not present significant differences; contamination by fecal coliforms in all treatments occurred; no contamination by Escherichia coli was observed in all treatments; all the Coefficients of Uniformity of Christiansen (CUC) observed were above 85%, except for treatment T3 where was 74%; chemical alterations in the soil occurred proportional to characteristics of waters used in the treatments.

  18. EVALUATION OF FUNGICIDES FOR CONTROLLING BOTTOM ROT OF ICEBERG LETTUCE, 2001 AND 2002

    Science.gov (United States)

    Application of fungicides such as Quadris, Pristin, Flint Rovral and Switch to the base of young lettuce plants after thinning and one week later reduced the incidence of disease caused by Rhizoctonia solani....

  19. Reproductive Response of Ewes Fed with Taiwan Grass Hay (Pennisetum purpureum Schum.) Supplemented with Duckweed (Lemna sp. and Spirodela sp.).

    Science.gov (United States)

    Zetina-Córdoba, P; Ortega-Cerrilla, M E; Sánchez Torres-Esqueda, M T; Herrera-Haro, J G; Ortega-Jiménez, E; Reta-Mendiola, J L; Vilaboa-Arroniz, J

    2012-08-01

    The effect of duckweed (DW) supplementation was evaluated on dry matter intake (DMI), presence and duration of estrus, percentage of ewes repeating estrus and pregnancy rate, as well as the concentration of progesterone (P4) in multiparous crossbred ewes from Pelibuey, Dorper, and Katahdin breeds, fed with Taiwan grass hay (TWH). Eighteen ewes with 39.7±4 kg mean body weight, kept in individual pens, were randomly assigned to one of the following treatments: T1: TWH, T2: TWH plus 200 g DW, T3: TWH plus 300 g DW. The ewes were synchronized with 40 mg fluorogestone acetate (FGA) and 400 UI equine chorionic gonadotropin (eCG). Data were analyzed as a completely randomized design using the GLM procedure. DW supplementation had no effect on dry matter intake (p>0.05); however, a slight decrease of TWH intake was observed as DW supplementation increased. No differences (p>0.05) were found in the beginning of estrus, percentage of ewes presenting it, its duration, or pregnancy rate. There were no differences (p>0.05) on P4 concentration among treatments, or treatmentxperiod interaction (p>0.05). However the period was significant (p<0.01), since the P4 levels increased as time increased after the removal of the FGA device and eCG application. PMID:25049670

  20. Diurnal change of light-dependent uridine incorporation into RNA in a log-day duckweed, Lemna gibba G3

    International Nuclear Information System (INIS)

    Light-dependent incorporation during subjective day and night of radioactive uridine into RNA of a long-day duckweed, Lemna gibba G3, was examined. When the dark treatment was started from the subjective night phase, the activity of uridine incorporation dropped approximately by half only after the very subjective night phase had passed or with the commencement of the subsequent subjective day phase. However, when the dark treatment was started from the subjective day phase, the incorporating activity promptly began to decrease and the inhibition increased with the length of the dark period until a final steady level (also at ca. 50% of the initial level) was reached after 24 hr of darkness. These two phases of different light sensitivities recurred daily under control of the physiological clock and the rhythm was reset by a light-on signal. The lowered incorporating activity due to the darkened day phase was recovered completely by a 12-hr or even 15-min white light period perturbing the succeeding night phase. That the incorporation of uridine in every RNA species, especially in chloroplast ribosomal RNA, was lowered by dark treatment of the day and night phases, was disclosed by MAK column chromatography and acrylamide gel electrophoresis. (author)

  1. Photoinduced toxicity of three polycyclic aromatic hydrocarbons (fluoranthene, pyrene, and naphthalene) to the duckweed Lemna gibba L. G-3

    International Nuclear Information System (INIS)

    The authors recently demonstrated that light dramatically enhances the hazards of three polycyclic aromatic hydrocarbons (PAHs), anthracene, phenanthrene, and benzo[a]pyrene, to the duckweed Lemna gibba L. G-3 (X.-D. Huang, D. G. Dixon, and B. M. Greenberg, 1993, Environ. Toxicol. Chem., 12, 1067-1077). To extend this research, growth and chlorosis were used as end points to assess the photoinduced toxicity of three additional PAHs, fluoranthene, pyrene, and naphthalene, to L. gibba in the presence of simulated solar radiation (a light source with a UV-B: UV-A:visible light ratio equivalent to that of sunlight). The phytotoxicity of these three PAHs was photoactivated, with ultraviolet radiation being the only spectral region that enhanced the harmful effects of the chemicals. Dose-response curves based on chemical concentration and light intensity revealed that the order of phytotoxic strength was fluoranthene > pyrene > naphthalene. To explore whether photomodification (in addition to photosensitization) of fluoranthene, pyrene, and naphthalene could contribute to photoinduced toxicity, the chemicals were irradiated prior to (as opposed to simultaneously with) application to the plans. The rates of photomodification of the three PAHs were rapid enough for the photooxidized compounds to contribute to toxicity, and the photomodified PAHs were more toxic than the parent compounds. As well, toxicity could be correlated to photomodification; impacts increased in parallel with the extent of photomodification

  2. Impacts of UV radiation and photomodification on the toxicity of PAHs to the higher plant Lemna gibba (duckweed)

    International Nuclear Information System (INIS)

    The toxicity of polycyclic aromatic hydrocarbons (PAHs) can be enhanced by both biotic and abiotic processes. This is exemplified by light, which, by virtue of the extensive ?-orbital systems of PAHs, can be a major factor in PAH toxicity. Light activation of PAHs is known to occur via photosensitization reactions (generation of singlet oxygen and superoxide) and potentially by photomodification of the chemicals (photooxidation and/or photolysis) to more toxic species. To examine the modes of PAH action in the light and determine if the photomodified compounds are hazardous, we investigated the photoinduced toxicity of anthracene, phenanthrene and benzo[a]pyrene to the aquatic higher plant Lemna gibba (a duckweed). Toxicity end points were inhibition of growth and extent of chlorosis. Light did indeed activate the phytotoxicity of PAHs, with UV radiation more effective than visible light. Dose-response curves based on chemical concentration and light intensity revealed the order of phytotoxic strength to be anthracene > phenanthrene > benzo[a]pyrene. To explore whether photomodified PAHs were contributing to toxicity, the chemicals were irradiated before toxicity testing. The rates of photomodification of the three PAHs were rapid (half-lives in hours), and the relative velocities were coincident with the order of toxic strength. Furthermore, the photomodified PAHs were more hazardous to Lemna than the intact compounds. Because interpretations of the potential impacts of PAHs in the environment are based mostly on measurements of the structurally intact chemicals, the severity of PAH hazards is possibly underestimated

  3. Effect of Sulfur Blended N-Fertilizers on Nitrogen Use Efficiency and Quality of Lettuce Yield

    OpenAIRE

    K.N. Al-Redhaiman; M.I.D. Helal; R.R. Shahin

    2003-01-01

    Volatilization of NH3 is a major factor affects ammonical fertilizer use efficiency particularly when N-fertilizers are surface applied to sandy soil characterized by high pH values and low CEC. Effect of blending various N-fertilizers; urea, U, ammonium sulfate, AS, ammonium nitrate, AN and di-ammonium phosphate, DAP; with elemental sulfur, on fertilizer-N utilization and quality of lettuce yield were studied. The results of lettuce yield grown in greenhouse showed significant increase in le...

  4. Dynamic Model as Attainment Effort of Nitrogen Synchronization at Lettuce Cultivation with Green Manure Paitan

    OpenAIRE

    Yuni Agung Nugroho; Elik Murni Ningtyas Ningsih

    2009-01-01

    Lettuce (Lactuca sativa) is vegetable crop that consumed part of the leaf and harvested at a phase of vegetative. Nitrogen play important role in growth at phase of vegetative. Nitrogen in spacious have the character of easy to lose because of leaching. Increasing yield of lettuce can be done by improving Nitrogen synchronization, that is precisely usage moment with ready moment of N during and amount of its. The research was aimed to study of the pattern nitrogen requirement for let...

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

    OpenAIRE

    Williams, Thomas R.; Marco, Maria L.

    2014-01-01

    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. ...

  6. Economic analysis of cucumber and lettuce intercropping under greenhouse in the winter-spring

    OpenAIRE

    Bráulio L.A. Rezende; Arthur B Cecílio Filho; Aurélio P Barros Júnior; Diego R. Q Porto; Maria Inez E.G. Martins

    2011-01-01

    The economical analysis complements the evaluation of the intercrop systems efficiency, considering besides the physical production of crops, the price of products according to their quality classification and time of the year. Intercropping systems of lettuce and cucumber in two plant populations under greenhouse were economically evaluated in winter-spring, in Jaboticabal City, São Paulo State, Brazil. The total operating cost (TOC) of cucumber and lettuce as sole crop and intercropping wer...

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

    OpenAIRE

    Shim, Chang Ki; Kim, Min Jeong; Kim, Yong Ki; Jee, Hyeong Jin

    2014-01-01

    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 sus...

  8. Antioxidant capacity and contents of phenols, ascorbic acid, ?-carotene and lycopene in lettuce

    OpenAIRE

    Zdravkovi? Jasmina M.; A?amovi?-?okovi? Gordana S.; Mladenovi? Jelena D.; Pavlovi? Radoš M.; Zdravkovi? 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...

  9. Nitrogenase Activity of Pseudomonas corrugata Isolated from Egyptian Lettuce

    OpenAIRE

    Emad A. Abada

    2006-01-01

    In the present study an isolate capable of root colonization of Egyptian Lettuce was isolated from the roots after selective enrichment. The isolated strain was identified as Pseudomonas corrugata by using Biochemical and Biolog identification system. The isolate has been found to be positive for nitrogenase activity. This root-colonized bacterium has not been previously isolated from Egyptian Lettuce and could be used as a bio-fertilizer.

  10. Searching the best equilibrium moisture equation for lettuce seeds using measures of curvature and bias

    OpenAIRE

    Bortolotti, Carolina T; Barrozo, Marcos A S

    2013-01-01

    In the present work, we performed a discrimination analysis of the nonlinear equations used to describe sorption isotherms of the lettuce seeds. The equilibrium data were obtained by the static method using saturated salt solutions. The best model to describe the equilibrium moisture of lettuce seeds was selected using measures of curvature and bias. The obtained results showed that the Copace equation was the best model in terms of nonsignificance for bias and nonlinearity measures.

  11. 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.

  12. Manure- and Biosolids-Resident Murine Norovirus 1 Attachment to and Internalization by Romaine Lettuce?

    OpenAIRE

    wei, Jie; Jin, Yan; Sims, Tom; Kniel, Kalmia E.

    2009-01-01

    The attachment of murine norovirus 1 (MNV) in biosolids, swine manure, and dairy manure to Romaine lettuce and internalization of this virus were evaluated. The MNV in animal manures had behavior similar to that of pure MNV; however, MNV in biosolids had significantly higher levels of attachment and internalization than pure MNV or MNV in manures. The incubation time did not affect the attachment of MNV in biosolids or manure. Confocal microscopy was used to observe MNV on lettuce after SYBR ...

  13. Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg

    OpenAIRE

    Jackson Marcondes; Ekkehard Hansen

    2008-01-01

    The obtainment of transgenic edible plants carrying recombinant antigens is a desired issue in search for economic alternatives viewing vaccine production. Here we report a strategy for genetic transformation of lettuce plants (Lactuca sativa L.) using the surface antigen HBsAg of hepatitis B virus. Transgenic lettuce seedlings were obtained through the application of a regulated balance of plant growth regulators. Genetic transformation process was acquired by cocultivation of cotyledons wit...

  14. Nitrate content in dandelion (Taraxacum officinale) and lettuce (Lactuca sativa) from organic and conventional origin: intake assessment.

    Science.gov (United States)

    Gorenjak, Alenka Hmelak; Koležnik, Urška Rizman; Cenci?, Avrelija

    2012-01-01

    To estimate the actual intake of nitrate by consumption of different lettuce varieties, 52 samples of lettuce of different origins and dandelion from 15 different areas of northeast Slovenia were analysed. For determination of actual nitrate content, a continuous flow method was used. The lowest nitrate content was detected in dandelion, with a mean value of 195?mg?kg(-1) (ranging 47-487?mg?kg(-1)). Nitrate content in lettuce of different origins ranged 85-3237?mg?kg(-1), with a mean value of 1196?mg?kg(-1). The mean nitrate content in organically cultivated lettuce was 890?mg?kg(-1), which was considerably lower than the nitrate level in conventionally cultivated lettuce (1298?mg?kg(-1)). Consumption of 100?g of dandelion would result in a maximal nitrate intake corresponding to 22% of the acceptable daily intake (ADI), with values up to seven times higher for lettuce. PMID:24779737

  15. Freshly characterization and storability of mini head lettuces at optimal and abusive temperatures.

    Science.gov (United States)

    Viacava, Gabriela E; Ponce, Alejandra G; Goyeneche, Rosario; Carrozzi, Liliana; Yommi, Alejandra; Roura, Sara I

    2016-01-01

    Selection of lettuce varieties less sensitive to quality deterioration and more tolerant to abusive temperatures during handling, transportation, and storage is essential to minimize economical and quality losses that affect both producers and consumers. This work was focused on the quality changes of four baby head lettuces (Lactuca sativa L.), two butter (red and green) and two oak-leaf (red and green) types, during storage at 0?? and 10?? for 10 days. Lettuce quality was determined by measuring bioactive content (ascorbic acid, total phenolics), physicochemical (total chlorophyll, browning potential), and microbiological indices. At harvest, red varieties presented lower browning potential and higher bioactive compounds but no differences were observed in microbial populations. During storage, ascorbic acid underwent first order degradation for all varieties, with a degradation rate at 10?? twice faster than at 0??. At 0??, only the red oak-leaf lettuce exhibited chlorophyll degradation, while at 10?? all varieties presented degradation. No changes were observed in total phenolics and browning potential of butter lettuces during storage at both temperatures. Microbial population counts were significant affected by the storage temperature. Red butter baby lettuce presented slightly better bioactive content and microbiological characteristics and then better storability. PMID:25631488

  16. 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.

  17. Identification of thaumatin-like protein and aspartyl protease as new major allergens in lettuce (Lactuca sativa)

    OpenAIRE

    Muñoz García, Esther; Luengo Sánchez, Olga; Haroun Díaz, Elisa; Sanz Maroto, Aroa; Palacín Gómez, Aranzazu; Díaz Perales, Araceli; Heras Gozalo, Manuel de las; Labrador Horrillo, Moises; Vivanco, Fernando; Cuesta-Herranz, Javier; Pastor Vargas, Carlos

    2013-01-01

    Scope: Today, about 2–8% of the population of Western countries exhibits some type of food allergy whose impact ranges from localized symptoms confined to the oral mucosa to severe anaphylactic reactions. Consumed worldwide, lettuce is a Compositae family vegetable that can elicit allergic reactions. To date, however, only one lipid transfer protein has been described in allergic reaction to lettuce. The aim of this study was to identify potential new allergens involved in lettuce al...

  18. EFFECTS OF TRICHODERMA HARZIANUM ON LETTUCE IN PROTECTED CULTIVATION

    Directory of Open Access Journals (Sweden)

    Ugur Bal

    2008-07-01

    Full Text Available Effects of Trichoderma harzianum on lettuce seedling development, plant quality characteristics at harvest and yield were investigated. Experiments were carried out in an unheated glasshouse where composted straw bales were used as the growing medium. A part of the experiment was carried out in a high tunnel where soil was the growing medium. Seeds were sown in peat and seedlings were grown in the presence of T. harzianum at dosages of 5, 10 and 15 g m-2 applied at sowing. Among the seedling characteristics studied only seedling fresh weight of cv. Yedikule was increased significantly. Effect of T. harzianum on lettuce yield was not statistically significant. In the glasshouse, the straw bales were composted with two different methods. In the method I, 134g N, 13g P, 25g K, and 76 g Ca, and in the method II, 54.3g N, 26g P, and 22.6g Ca were provided to the straw bales. The marketable yield of cv. Yedikule from the straw bales of method I was 503 g plant-1 from 15 g m-2 whereas the control remained the lowest with 425 g plant-1. For the same cultivar grown on the method II the highest marketable yield was obtained from 10 g m-2 with 303 g plant-1 compared to the control (150 g plant-1. The cv. Coolguard grown in the straw bales was tested only with the method I and the highest yield was from 15 g m-2 with 570 g plant-1 compared to 551 g plant-1 from the control. Dosage main effect regarding marketable yield in soil in the tunnel was not significant.

  19. Pilot-scale comparison of four duckweed strains from different genera for potential application in nutrient recovery from wastewater and valuable biomass production.

    Science.gov (United States)

    Zhao, Y; Fang, Y; Jin, Y; Huang, J; Bao, S; Fu, T; He, Z; Wang, F; Wang, M; Zhao, H

    2015-01-01

    The application potential of four duckweed strains from four genera, Wolffia globosa 0222, Lemna japonica 0223, Landoltia punctata 0224 and Spirodela polyrhiza 0225, were compared in four parallel pilot-scale wastewater treatment systems for more than 1 year. The results indicated that each duckweed strain had unique potential advantages. Unlike L. japonica 0223 and La. punctata 0224, which grow throughout the year, S. polyrhiza 0225 and W. globosa 0222 do not survive cold weather. For year round performance, L. japonica 0223 was best not only in dry biomass production (6.10 g·m(-2) ·day(-1) ), but also in crude protein (35.50%), total amino acid (26.83%) and phosphorus (1.38%) content, plus recovery rates of total nitrogen (TN), total phosphorus (TP) and CO2 (0.31, 0.085 and 7.76 g·m(-2) ·day(-1) , respectively) and removal rates of TN and TP (0.66 and 0.089 g·m(-2) ·day(-1) , respectively). This strongly demonstrates that L. japonica 0223 performed best in wastewater treatment and protein biomass production. Under nutrient starvation conditions, La. punctata 0224 had the highest starch content (45.84%), dry biomass production (4.81 g·m(-2) ·day(-1) ) and starch accumulation (2.9 g·m(-2) ·day(-1) ), making it best for starch biomass production. W. globosa 0222 and S. polyrhiza 0225 showed increased flavonoid biomass production, with higher total flavonoid content (5.85% and 4.22%, respectively) and high dominant flavonoids (>60%). This study provides useful information for selecting the appropriate local duckweed strains for further application in wastewater treatment and valuable biomass production. PMID:24942851

  20. High-Yield Expression of M2e Peptide of Avian Influenza Virus H5N1 in Transgenic Duckweed Plants.

    Science.gov (United States)

    Firsov, Aleksey; Tarasenko, Irina; Mitiouchkina, Tatiana; Ismailova, Natalya; Shaloiko, Lyubov; Vainstein, Alexander; Dolgov, Sergey

    2015-07-01

    Avian influenza is a major viral disease in poultry. Antigenic variation of this virus hinders vaccine development. However, the extracellular domain of the virus-encoded M2 protein (peptide M2e) is nearly invariant in all influenza A strains, enabling the development of a broad-range vaccine against them. Antigen expression in transgenic plants is becoming a popular alternative to classical expression methods. Here we expressed M2e from avian influenza virus A/chicken/Kurgan/5/2005(H5N1) in nuclear-transformed duckweed plants for further development of avian influenza vaccine. The N-terminal fragment of M2, including M2e, was selected for expression. The M2e DNA sequence fused in-frame to the 5' end of ?-glucuronidase was cloned into pBI121 under the control of CaMV 35S promoter. The resulting plasmid was successfully used for duckweed transformation, and western analysis with anti-?-glucuronidase and anti-M2e antibodies confirmed accumulation of the target protein (M130) in 17 independent transgenic lines. Quantitative ELISA of crude protein extracts from these lines showed M130-?-glucuronidase accumulation ranging from 0.09-0.97 mg/g FW (0.12-1.96 % of total soluble protein), equivalent to yields of up to 40 ?g M2e/g plant FW. This relatively high yield holds promise for the development of a duckweed-based expression system to produce an edible vaccine against avian influenza. PMID:25740321

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

    International Nuclear Information System (INIS)

    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)

  2. Obtaining resistant lettuce progenies to downy mildew / Obtenção de progênies de alface crespa resistentes ao míldio

    Scientific Electronic Library Online (English)

    Renata, Castoldi; Hamilton CO, Charlo; Danilo M, Melo; Willame S, Candido; Pablo F, Vargas; Tagli, Dalpian; Leila T, Braz.

    Full Text Available A alface é a hortaliça folhosa mais consumida no Brasil. No entanto, a dificuldade em produzi-la vem aumentando, principalmente pela infestação das áreas de produção por Bremia lactucae, sendo o uso de cultivares com resistência horizontal, a alternativa mais viável no controle da doença. Diante do [...] exposto, o objetivo do presente trabalho foi obter progênies de alface crespa resistentes às raças de míldio SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07. O trabalho de melhoramento consistiu de duas etapas: cruzamento dos parentais para obtenção das progênies de alface crespa resistentes e teste de resistência das progênies às raças de B. lactucae. Os parentais utilizados na obtenção das progênies resistentes foram Argeles e linhagem JAB 4-13-7, visando a obtenção de progênies de alface do tipo crespa, com os fatores de resistência R-18 e R-38. Para tanto, adotou-se o método genealógico, tendo como padrão, para as seleções, a cultivar Hortência e o genótipo JAB 4-13-7. Após a seleção e autofecundação das plantas no campo, efetuou-se o teste de resistência ou suscetibilidade, por meio da inoculação nas progênies oriundas dos cruzamentos, de uma mistura de água destilada + esporângios de B. lactucae das raças SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 e SPBl:07 obtidas de isolados coletados nos anos de 2008 a 2010. Quinze dias após a inoculação, as plântulas foram selecionadas, descartando aquelas que possuíam esporulação e pontos necróticos causados por B. lactucae. Pelo método genealógico, selecionaram-se 69 progênies F3 com boas características agronômicas. No entanto, após o teste de resistência ou suscetibilidade, somente 19 apresentaram todas as plantas resistentes ao míldio. Abstract in english Lettuce is the most consumed leafy vegetable in Brazil. Its production, nonetheless, is increasing in difficulties mainly due to the infestation of producing areas with Bremia lactucae. Thus, the use of horizontal resistant cultivars is the most viable alternative in controlling progress of disease. [...] So, the objective of this study was to obtain resistant lettuce progenies to the races of downy mildew: SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07. The breeding consisted of two stages: crossover of parentals to obtain the resistant lettuce progenies and endurance test of the progeny to B. lactucae races. The parentals used to obtain progenies with resistance factor R-18 and R-38 were: JAB 4-13-7 and JAB 4-13-7. The Pedigree method was used for obtaining the progeny, using as default selections the Hortência cultivar and JAB 4-13-7genotype. After selection and selfing of the plants in the field, the resistance or susceptibility test was realized, by inoculation of the progenies from the crosses, with mixture of distilled water + sporangia of B. lactucae races SPBl:01, SPBl:02, SPBl:03, SPBl:04, SPBl:05, SPBl:06 and SPBl:07 obtained from isolates collected in the years 2008-2010. Fifteen days after inoculation, the seedlings were selected as resistant or susceptible, discarding those presenting sporulation and necrotic spots caused by B. lactucae. Through the Pedigree method we found 69 progenies F3 with good agronomic characteristics. However, after resistance or susceptibility test, only 19 showed all the plants resistant to downy mildew.

  3. Arbuscular mycorrhizal symbiosis induces strigolactone biosynthesis under drought and improves drought tolerance in lettuce and tomato.

    Science.gov (United States)

    Ruiz-Lozano, Juan Manuel; Aroca, Ricardo; Zamarreño, Ángel María; Molina, Sonia; Andreo-Jiménez, Beatriz; Porcel, Rosa; García-Mina, José María; Ruyter-Spira, Carolien; López-Ráez, Juan Antonio

    2016-02-01

    Arbuscular mycorrhizal (AM) symbiosis alleviates drought stress in plants. However, the intimate mechanisms involved, as well as its effect on the production of signalling molecules associated with the host plant-AM fungus interaction remains largely unknown. In the present work, the effects of drought on lettuce and tomato plant performance and hormone levels were investigated in non-AM and AM plants. Three different water regimes were applied, and their effects were analysed over time. AM plants showed an improved growth rate and efficiency of photosystem II than non-AM plants under drought from very early stages of plant colonization. The levels of the phytohormone abscisic acid, as well as the expression of the corresponding marker genes, were influenced by drought stress in non-AM and AM plants. The levels of strigolactones and the expression of corresponding marker genes were affected by both AM symbiosis and drought. The results suggest that AM symbiosis alleviates drought stress by altering the hormonal profiles and affecting plant physiology in the host plant. In addition, a correlation between AM root colonization, strigolactone levels and drought severity is shown, suggesting that under these unfavourable conditions, plants might increase strigolactone production in order to promote symbiosis establishment to cope with the stress. PMID:26305264

  4. Comparative Study of Lettuce and Radish Grown Under Red and Blue Light-Emitting Diodes (LEDs) and White Fluorescent Lamps

    Science.gov (United States)

    Mickens, Matthew A.

    2012-01-01

    Growing vegetable crops in space will be an essential part of sustaining astronauts during long-term 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 production, there have also been recent interests in analyzing the subtle effects of green light on plant growth, and to determine if it serves as a source of growth enhancement or suppression. A comparative study was performed on two short cycle crops of lettuce (Outredgeous) and radish (Cherry Bomb) grown under two light treatments. The first treatment being red and blue LEDs, and the second treatment consisting of white fluorescent lamps which contain a portion of green light. In addition to comparing biomass production, physiological characterizations were conducted on how the light treatments influence morphology, water use, chlorophyll content, and the production of A TP within plant tissues.

  5. Frequência de Lettuce big-vein associated virus e Mirafiori lettuce big-vein virus em Plantas de alface no Estado de São Paulo e transmissão através de extrato vegetal e solo / Frequency of Lettuce big-vein associated virus and Mirafiori lettuce big-vein virus in symptomatic and assymptomatic lettuce plants and sap and soil transmission

    Scientific Electronic Library Online (English)

    Márcio Martinello, Sanches; Renate, Krause-Sakate; Francisco Murilo, Zerbini; Marlene, Rosales; Olivier, Le Gall; Marcelo Agenor, Pavan.

    2007-12-01

    Full Text Available A presença de sintomas de 'big vein' ou engrossamento das nervuras em alface e a associação do Lettuce big-vein associated virus (LBVaV) e Mirafiori lettuce big-vein virus (MLBVV) foram verificadas por RT-PCR utilizando-se oligonucleotídeos específicos para ambos os vírus. Foram coletadas 366 planta [...] s sintomáticas nas regiões de Bauru, Campinas e Mogi das Cruzes no estado de São Paulo nos meses de junho e setembro de 2004 e abril e julho de 2005, e 18 plantas assintomáticas na região de Mogi das Cruzes no mês de dezembro de 2004. Infecção mista do LBVaV e MLBVV foi detectada em 76,2% das plantas sintomáticas, em 11,5% somente o MLBVV foi detectado e em 6,6% somente o LBVaV. Nas plantas assintomáticas coletadas em dezembro na região de Mogi das Cruzes, em áreas de alta incidência da doença durante o inverno, foi detectada a presença de MLBVV em 9 amostras e LBVaV em 7 amostras. Quatro dessas amostras apresentaram infecção mista, indicando que o desenvolvimento de sintomas depende de fatores abióticos, como temperatura. A inoculação via extrato vegetal a partir de plantas de alface com infecção mista pelo MLBVV e LBVaV foi realizada a 16°C/ 10°C (dia/noite) e fotoperíodo de 11 horas, verificando-se que o MLBVV foi transmitido para Nicotiana tabacum TNN, N. rustica, N. occidentalis, Chenopodium quinoa e para as cultivares de alface Trocadero e White Boston, enquanto o LBVaV foi transmitido apenas para a alface White Boston. Entretanto, nenhuma destas plantas apresentou sintomas da doença, com exceção de C. quinoa que apresentou sintomas de lesões locais. Plantio em solo proveniente de áreas com histórico da doença de Mogi das Cruzes permitiu a transmissão do LBVaV para alface cv. White Boston e do MLBVV para alface cv. Trocadero e White Boston, embora apenas a cv. White Boston tenha apresentado sintomas da doença. Em conjunto, estes resultados demonstram a dificuldade de transmissão de ambos os vírus, mesmo em condições de laboratório. Abstract in english The occurrence of big vein disease symptoms and the association of Lettuce big-vein associated virus (LBVaV) and Mirafiori lettuce big-vein virus (MLBVV) was evaluated by RT-PCR using specific primers for both viruses. A total of 366 symptomatic plants were collected during June and September 2004 a [...] nd during April and July 2005 at Bauru, Campinas and Mogi das Cruzes in São Paulo state, and 18 symptomless plants were collected in Mogi das Cruzes on December 2004. Mixed infection was detected in 76,2% of the symptomatic plants, 11,5% had only MLBVV and 6,6% had only LBVaV. In the symptomless plants collected in areas with high incidence of the disease throughout the winter, MLBVV was found in 9 plants and LBVaV in 7 plants. Four plants had both viruses, indicating that symptom development depends on abiotic factors, such as temperature. Plants with MLBVV and LBVaV (mixed infection) were used as source of virus in a host range assay at 16C/ 10°C (day/ night) and 11h light period. MLBVV was transmitted to Nicotiana tabacum TNN, N. rustica, N. occidentalis, Chenopodium quinoa and lettuce cv. Trocadero and White Boston, while LBVaV was transmitted only to lettuce cv. White Boston. No symptons could be verified for these plants with the exception of C. quinoa that showed local lesions. Transmission through soil in areas with high incidence of the disease was observed for LBVaV to lettuce cv. White Boston and MLBVV for lettuce cv. Trocadero and White Boston, but only cv. White Boston showed symptoms. Together, these results demonstrate the difficulties in transmitting both viruses, even under controlled laboratory conditions.

  6. Frequência de Lettuce big-vein associated virus e Mirafiori lettuce big-vein virus em Plantas de alface no Estado de São Paulo e transmissão através de extrato vegetal e solo Frequency of Lettuce big-vein associated virus and Mirafiori lettuce big-vein virus in symptomatic and assymptomatic lettuce plants and sap and soil transmission

    Directory of Open Access Journals (Sweden)

    Márcio Martinello Sanches

    2007-12-01

    Full Text Available A presença de sintomas de 'big vein' ou engrossamento das nervuras em alface e a associação do Lettuce big-vein associated virus (LBVaV e Mirafiori lettuce big-vein virus (MLBVV foram verificadas por RT-PCR utilizando-se oligonucleotídeos específicos para ambos os vírus. Foram coletadas 366 plantas sintomáticas nas regiões de Bauru, Campinas e Mogi das Cruzes no estado de São Paulo nos meses de junho e setembro de 2004 e abril e julho de 2005, e 18 plantas assintomáticas na região de Mogi das Cruzes no mês de dezembro de 2004. Infecção mista do LBVaV e MLBVV foi detectada em 76,2% das plantas sintomáticas, em 11,5% somente o MLBVV foi detectado e em 6,6% somente o LBVaV. Nas plantas assintomáticas coletadas em dezembro na região de Mogi das Cruzes, em áreas de alta incidência da doença durante o inverno, foi detectada a presença de MLBVV em 9 amostras e LBVaV em 7 amostras. Quatro dessas amostras apresentaram infecção mista, indicando que o desenvolvimento de sintomas depende de fatores abióticos, como temperatura. A inoculação via extrato vegetal a partir de plantas de alface com infecção mista pelo MLBVV e LBVaV foi realizada a 16°C/ 10°C (dia/noite e fotoperíodo de 11 horas, verificando-se que o MLBVV foi transmitido para Nicotiana tabacum TNN, N. rustica, N. occidentalis, Chenopodium quinoa e para as cultivares de alface Trocadero e White Boston, enquanto o LBVaV foi transmitido apenas para a alface White Boston. Entretanto, nenhuma destas plantas apresentou sintomas da doença, com exceção de C. quinoa que apresentou sintomas de lesões locais. Plantio em solo proveniente de áreas com histórico da doença de Mogi das Cruzes permitiu a transmissão do LBVaV para alface cv. White Boston e do MLBVV para alface cv. Trocadero e White Boston, embora apenas a cv. White Boston tenha apresentado sintomas da doença. Em conjunto, estes resultados demonstram a dificuldade de transmissão de ambos os vírus, mesmo em condições de laboratório.The occurrence of big vein disease symptoms and the association of Lettuce big-vein associated virus (LBVaV and Mirafiori lettuce big-vein virus (MLBVV was evaluated by RT-PCR using specific primers for both viruses. A total of 366 symptomatic plants were collected during June and September 2004 and during April and July 2005 at Bauru, Campinas and Mogi das Cruzes in São Paulo state, and 18 symptomless plants were collected in Mogi das Cruzes on December 2004. Mixed infection was detected in 76,2% of the symptomatic plants, 11,5% had only MLBVV and 6,6% had only LBVaV. In the symptomless plants collected in areas with high incidence of the disease throughout the winter, MLBVV was found in 9 plants and LBVaV in 7 plants. Four plants had both viruses, indicating that symptom development depends on abiotic factors, such as temperature. Plants with MLBVV and LBVaV (mixed infection were used as source of virus in a host range assay at 16C/ 10°C (day/ night and 11h light period. MLBVV was transmitted to Nicotiana tabacum TNN, N. rustica, N. occidentalis, Chenopodium quinoa and lettuce cv. Trocadero and White Boston, while LBVaV was transmitted only to lettuce cv. White Boston. No symptons could be verified for these plants with the exception of C. quinoa that showed local lesions. Transmission through soil in areas with high incidence of the disease was observed for LBVaV to lettuce cv. White Boston and MLBVV for lettuce cv. Trocadero and White Boston, but only cv. White Boston showed symptoms. Together, these results demonstrate the difficulties in transmitting both viruses, even under controlled laboratory conditions.

  7. Plant growth, metabolism and adaptation in relation to stress conditions. XXI. Reversal of harmful NaCl-effects in lettuce plants by foliar application with urea

    OpenAIRE

    Mahmoud Elbaz Younis; Mohammed Naguib Hasaneen; Adel Rezk Ahmed; Dalia Mohammed El-Bialy

    2008-01-01

    In relation to water control levels, administration of NaCl at low (3 dSm-1), medium (5 dSm-1) or high (7 dSm-1) concentration, in the growth medium of the lettuce plants, induced significant decreases in growth components as well as in the metabolites and enzymes determined, at vegetative and adult growth stages. On the other hand, significant increases in all growth and photosynthetic components determined, as well as in carbohydrate contents and in the activities of the antioxidant enz...

  8. Increased polycyclic aromatic hydrocarbon toxicity following their photomodification in natural sunlight: impacts on the duckweed Lemna gibba L. G-3

    International Nuclear Information System (INIS)

    The authors previously demonstrated that simulated solar radiation (SSR), with a fluence rate of only 40 mumol m-2 sec-1, increased polycyclic aromatic hydrocarbon (PAH) toxicity to the duckweed Lemna gibba and that PAHs photomodified in SSR (generally oxygenation of the ring system) are more toxic than the parent compounds (Huang et al., Environ. Toxicol. Chem., 1993, 12, 1067-1077). It is not known, however, to what extent toxicity of PAHs can increase due to photomodification. Thus, natural sunlight, which has a high fluence rate (approximately 2000 mumol m-2 sec-1), was used to photomodify anthracene, benzo[a]pyrene, fluoranthene, phenanthrene, and pyrene. Toxicity was based on growth inhibition of L. gibba, measured as the rate of production of new leaves over an 8-day period. Initially, the toxicity of the PAHs applied in intact form was probed, with the compounds demonstrating greater toxicity in sunlight than in SSR. Next the PAHs were photomodified in sunlight prior to incubation with the plants. The half-lives of the PAHs in sunlight ranged from 12 min to 30 hr. Although most of the products of PAH photomodification are not yet identified, the degree that PAH toxicity increased following photomodification in sunlight could still be probed. The mixtures of photomodified chemicals that were derived from each PAH in sunlight were applied of L. gibba and growth inhibition under 100 mumol m-2 sec-1 of SSR was determined. The LC50s for the PAH photoproducts generated in sunlight were an order of magnitude lower than the LC50s for the PAHs applied in intact form. (author)

  9. Occurrence of Cryptosporidium spp. oocysts in low quality water and on vegetables irrigated with low quality water in Kumasi, Ghana

    DEFF Research Database (Denmark)

    Petersen, Tobias B; Petersen, Heidi H.

    Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. Oocysts were stored approx. six weeks at 4C° before enumeration and approx. two weeks on slides at room temperature. Oocysts were subsequently washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3,268 per 10L water and 11 – 118 oocysts per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water samples from both rivers and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

  10. 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. PMID:26850143

  11. Ultralow oxygen treatment for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), on iceberg lettuce. I. Temperature, time & oxygen level on insect mortality & lettuce quality

    Science.gov (United States)

    Ultralow oxygen (ULO) treatments with different oxygen levels, treatment times, and temperatures were studied to determine responses of western flower thrips and effects on postharvest quality of iceberg lettuce. Over 99.6% mortality rates of thrips were achieved in three ULO treatments of 2, 3, and...

  12. Toxicological effects of copper oxide nanoparticles on the growth rate, photosynthetic pigment content, and cell morphology of the duckweed Landoltia punctata.

    Science.gov (United States)

    Lalau, Cristina Moreira; Mohedano, Rodrigo de Almeida; Schmidt, Éder C; Bouzon, Zenilda L; Ouriques, Luciane C; dos Santos, Rodrigo W; da Costa, Cristina H; Vicentini, Denice S; Matias, William Gerson

    2015-01-01

    Recently, the application of copper oxide nanoparticles (CuO-NPs) has increased considerably, primarily in scientific and industrial fields. However, studies to assess their health risks and environmental impacts are scarce. Therefore, the present study aims to evaluate the toxicological effects of CuO-NPs on the duckweed species Landoltia punctata, which was used as a test organism. To accomplish this, duckweed was grown under standard procedures according to ISO DIS 20079 and exposed to three different concentrations of CuO-NPs (0.1, 1.0, and 10.0?g L(-1)), with one control group (without CuO-NPs). The toxicological effects were measured based on growth rate inhibition, changes in the plant's morphology, effects on ultrastructure, and alterations in photosynthetic pigments. The morphological and ultrastructural effects were evaluated by electronic, scanning and light microscopic analysis, and CuO-NPs were characterized using transmission electron microscopy (TEM), zeta potential, and superficial area methods of analysis. This analysis was performed to evaluate nanoparticle size and form in solution and sample stability. The results showed that CuO-NPs affected morphology more significantly than growth rate. L. punctata also showed the ability to remove copper ions. However, for this plant to be representative within the trophic chain, the biomagnification of effects must be assessed. PMID:25005714

  13. Economic analysis of organic greenhouse lettuce production in Turkey Análise econômica da produção orgânica de alface em estufas na Turquia

    Directory of Open Access Journals (Sweden)

    Sait Engindeniz

    2006-06-01

    Full Text Available Health issues and environmental concerns have drawn the attention to organic agriculture aiming to protect the natural balance and to produce without damaging the environment. This study aims determining economic feasibility of organic greenhouse lettuce (Lactuca sativa L. in an on farm trial, to foster organic greenhouse vegetable production in the preservation area of Tahtali Dam, projected as the sole water resource of Izmir, Turkey's third largest. A 384 m² greenhouse, constructed of galvanized metal tubing anchored and covered with a polyethylene was analyzed to identify typical operation procedures, and to determine unitary construction and operation cost. Organic lettuces were produced during autumn season of 2001-2002, testing different organic fertilizer applications, including two rates of farmyard and poultry manure (30 and 50 t ha-1 with and without two organic fertilizers based on either bacteria or algae. Economical analysis was performed according to different organic fertilizer applications. Cost, yield, and price data were analyzed to determine the profitability of a typical operation. Net return obtained from organic lettuce growing ranged between us $ 0.376 and us $ 0.901 m-2, as a result of different fertilizer applications.Preocupações sanitárias e ambientais têm atraído a atenção para a prática da agricultura orgânica como meio de proteger o balanço ambiental e produzir sem danificar o ambiente. Este estudo objetiva determinar a viabilidade econômica da produção em estufa da alface (Latuca sativa L. em um ensaio de campo, a fim de incentivar a produção orgânica de vegetais na área de preservação do Reservatório Tahtali, projetado como o único recurso hídrico de Izmir, a terceira maior cidade da Turquia. Uma estufa de tubos galvanizados (384 m², ancorados e cobertos com polietileno, foi analisada para identificar procedimentos operacionais padronizados e determinar custos unitários de construção e operação. Alfaces orgânicas foram produzidas no outono de 2001-2002, testando diferentes aplicações de sobras compostadas e esterco de granja avícola como fertilizantes orgânicos (30 e 50 t ha-1, com ou sem a adição de fertilizantes comerciais bacterianos ou algais. A análise econômica foi feita de acordo com as quantidades de fertilizantes utilizadas. A determinação da lucratividade foi feita com base na análise de dados de custos, produtividade e preço. O lucro líquido obtido da produção orgânica de alface em estufa variou entre US$ 0.376 e US$ 0.901 m-2.

  14. Teores de nutrientes na alface irrigada com água residuária aplicada por sistemas de irrigação / Nutrients levels in lettuce irrigated with wastewater applied by irrigation systems

    Scientific Electronic Library Online (English)

    Delvio, Sandri; Edson E., Matsura; Roberto, Testezlaf.

    2006-04-01

    Full Text Available Desenvolveu-se este trabalho para avaliar a composição química da parte aérea da alface, cv. Elisa, irrigada com água residuária tratada com leitos cultivados com macrófitas e água de um depósito de fonte hídrica superficial, cultivada em Latossolo Vermelho Distroférrico, utilizando-se dos sistemas [...] de irrigação por aspersão convencional, gotejamento subterrâneo e superficial. O experimento compreendeu o período de 17-8 a 3-10-2001, e as análises químicas da alface foram realizadas aos 47 dias após o transplantio das mudas em campo. A parte aérea da alface foi analisada quanto ao teor de nitrogênio total, nitrato, fósforo, potássio, cálcio, magnésio, enxofre, ferro, manganês, cobre, zinco, sódio, boro, cobalto e molibdênio. O sódio e o enxofre apresentaram teores maiores que o máximo adequado na parte aérea da alface e o magnésio menor, enquanto para os demais elementos químicos foram normais e adequados, considerando os padrões para plantas bem nutridas, não sendo influenciados pelo tipo de água. O sódio foi o elemento químico que apresentou a maior elevação na parte aérea nos tratamentos irrigados com água residuária, apresentando diferença significativa em relação à água do depósito superficial nos três sistemas de irrigação. A utilização dos diferentes sistemas de irrigação para aplicação de água residuária tratada com leitos cultivados com macrófitas não interferiu no teor de nutrientes na parte aérea. Abstract in english A trial was carried out to evaluate the chemical composition in the aerial part of lettuce, cv. 'Elisa', irrigated with wastewater treated with constructed wetland and source deposit water, grown on a Rhodic Hapludox Soil, using the irrigation systems sprinkle, subsurface drip and surface drip irrig [...] ation. The experiment was carried out from August 17th to October 3rd of 2001 and the chemical analyses of the lettuce were accomplished to 47 days after transplanting of the seedling. The aerial part of the lettuce was analyzed as for the levels of total nitrogen, nitrate, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, sodium, boron, cobalt and molybdenum. The sodium and the sulfur presented higher levels than the maximum suitable in the aerial part of the lettuce and the smallest level of magnesium, while other chemical elements analyzed were normal and appropriate considering the standard for well-nourished plants, not being influenced by the water type. The sodium was the chemical element that presented the highest levels in the aerial part of the lettuce in the treatments irrigated with wastewater, presenting significant difference in relationship to the treatments irrigated with source deposit water in the three irrigation systems. The use of the different irrigation systems by the application of wastewater treated with constructed wetland did not interfere in the levels of nutrients in the aerial part of the lettuce.

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

    DEFF Research Database (Denmark)

    Jensen, Annette Nygaard; Storm, Christina; Forslund, A.; Baggesen, Dorte Lau; Dalsgaard, A.

    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...

  16. 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.

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

    International Nuclear Information System (INIS)

    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

  18. 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. PMID:16604461

  19. 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.

  20. 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. PMID:25367329

  1. 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. PMID:26616925

  2. Effect of different concentrations of diluted seawater on yield and quality of lettuce

    Scientific Electronic Library Online (English)

    Ahmet, Turhan; Hayrettin, Kuscu; Nese, Ozmen; Mehmet, Sitki Serbeci; Ali, Osman Demir.

    2014-03-01

    Full Text Available This study was carried out to investigate the effects of irrigating lettuce (Lactuca sativa L. cv. Funly) with different concentrations of diluted seawater (0%, 2.5%, 5%, 10%, 15%, 20%) on the fresh yield, marketable yield and quality (DM, total soluble solids, titratable acidity, total sugar, vitam [...] in C, NO3-N, protein, and total oxalate content). The experiments were conducted in a greenhouse in the autumn of 2012. The fresh yield, marketable yield, and DM of lettuce irrigated with 2.5% and 5% seawater were similar to those of control, but these parameters decreased in response to 10% seawater, and the lowest values were obtained in response to 20% seawater. The 2.5% seawater treatment had no effect on the vitamin C and NO3-N content, but both significantly decreased when lettuce was irrigated with seawater concentrations higher than 2.5%. Total soluble solids, total sugar, and protein content significantly increased in response to low salinity (2.5% and 5%) but decreased in response to increasing seawater stress. The titratable acidity values remained unchanged under the various saline conditions. Irrigation with diluted seawater did not affect the total oxalate content up to a concentration of 5%, but increasing the concentration of seawater above 5% increased oxalate content. The results of this study demonstrated that low concentrations of seawater are suitable for lettuce production and lettuce can be grown successfully using diluted seawater at concentrations of 2.5% and 5%.

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

    International Nuclear Information System (INIS)

    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

  4. 76 FR 81468 - Notice of Decision to Authorize the Importation of Shredded Lettuce From Egypt Into the...

    Science.gov (United States)

    2011-12-28

    ... published a notice \\1\\ in the Federal Register on August 17, 2011 (76 FR 50992-50993, Docket No. APHIS-2011... Lettuce From Egypt Into the Continental United States AGENCY: Animal and Plant Health Inspection Service... into the continental United States of fresh shredded lettuce from Egypt. Based on the findings of...

  5. 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

    ... Importation of Shredded Lettuce From Egypt AGENCY: Animal and Plant Health Inspection Service, USDA. ACTION... Egypt. Based on this analysis, we believe that the application of one or more designated phytosanitary... weeds via the importation of fresh shredded lettuce from Egypt. We are making the pest risk...

  6. Antimicrobial activity of Cinnamaldehyde and Sporan against Escherichia coli O157:H7 and Salmonella on lettuce

    Science.gov (United States)

    Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce wash; the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Lettuce were cut into pieces (...

  7. Essential oils reduce Escherichia coli O157:H7 and Salmonella on iceberg and romaine lettuce without affecting produce quality

    Science.gov (United States)

    Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce wash; the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Cut lettuce pieces (3 x 2 cm) ...

  8. Fifteen years of verticillium wilt of lettuce in america’s salad bowl: a tale of immigration, subjugation and abatement.

    Science.gov (United States)

    Lettuce is a popular leafy vegetable that is globally cultivated. The US ranks second in production, with coastal California producing half of the US supply. In 1995, Verticillium wilt caused by the soil borne fungus Verticillium dahliae was identified as a disease of lettuce in coastal California, ...

  9. Iceberg lettuce breeding lines with resistance to Verticillium wilt caused by race 1 isolates of Verticillium dahliae.

    Science.gov (United States)

    The Agricultural Research Service, United States Department of Agriculture and the University of California, Davis, announce the release of two breeding lines of lettuce (Lactuca sativa L.). Lines RH08-0472 and RH08-0475 are F9 iceberg type lettuce breeding lines with resistance to Verticillium wil...

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

    Science.gov (United States)

    This study was conducted to investigate radiation tolerance of fresh-cut Iceberg lettuce and spinach. 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 sam...

  11. 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...

  12. Variation for Big Vein Resistance in Lactuca virosa L. and Introgression of Resistance into Cultivated Lettuce (Lactuca sativa L.).

    Science.gov (United States)

    Big vein is a damaging disease of lettuce (Lactuca sativa L.) caused by the Olpidium brassicae vectored Mirafiori Lettuce Big Vein Virus (MLBVV). Resistance to this disease is needed since no feasible cultural control methods have been identified. Partial resistance is available in cultivars such a...

  13. ROLE OF PH IN THE ACCUMULATION OF LEAD AND NICKEL BY COMMON DUCKWEED (LEMNA MINOR

    Directory of Open Access Journals (Sweden)

    Leela Kaur

    2012-11-01

    Full Text Available Heavy metals are the most common non-biodegradable pollutants. Various remediation methods have been used for the treatment of heavy metal contaminated water. However, phytoremediation technology is currently being used due to its economically feasible and ecologically viable advantages. The aim of this study was to examine the role of pH in the accumulation capacity of Lemna minor in Pb and Ni contaminated water. The removal rate of Pb and Ni from L. minor was 99.99% and 99.30% respectively, after 28 days of exposure to the 10 mgl-1 Pb and Ni contaminated water at pH 5-6 and pH 6 respectively. // //

  14. ROLE OF PH IN THE ACCUMULATION OF LEAD AND NICKEL BY COMMON DUCKWEED (LEMNA MINOR

    Directory of Open Access Journals (Sweden)

    Leela Kaur

    2012-12-01

    Full Text Available Heavy metals are the most common non-biodegradable pollutants. Various remediation methods have been used for the treatment of heavy metal contaminated water. However, phytoremediation technology is currently being used due to its economically feasible and ecologically viable advantages. The aim of this study was to examine the role of pH in the accumulation capacity of Lemna minor in Pb and Ni contaminated water. The removal rate of Pb and Ni from L. minor was 99.99% and 99.30% respectively, after 28 days of exposure to the 10 mgl-1 Pb and Ni contaminated water at pH 5-6 and pH 6 respectively. // //

  15. Occurrence of Cryptosporidiumspp. oocysts in low quality water and on vegetables in Kumasi, Ghana

    DEFF Research Database (Denmark)

    Petersen, T. B.; Petersen, H. H.

    2014-01-01

    Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period of, September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. After approximately six weeks of storage at 4C°, analysis and additional storage on slides, oocysts were washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes after. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3268 per 10 L water and 11 – 118 oocyst per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

  16. Occurence of Cryptosporidium spp. in low quality water and on vegetables in Kumasi, Ghana

    DEFF Research Database (Denmark)

    Petersen, T. B.; Petersen, H. H.

    2014-01-01

    Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period of, September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. After approximately six weeks of storage at 4C°, analysis and additional storage on slides, oocysts were washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes after. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3268 per 10 L water and 11 – 118 oocyst per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

  17. Occurrence of Cryptosporidiumspp. oocysts in low quality water and on vegetables in Kumasi, Ghana.

    DEFF Research Database (Denmark)

    Petersen, Tobias; Petersen, Heidi Huus

    Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period of, September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. After approximately six weeks of storage at 4C°, analysis and additional storage on slides, oocysts were washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes after. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3268 per 10 L water and 11 – 118 oocyst per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

  18. ROLE OF PH IN THE ACCUMULATION OF LEAD AND NICKEL BY COMMON DUCKWEED (LEMNA MINOR)

    OpenAIRE

    Leela Kaur; Kasturi Gadgil; Satyawati Sharma

    2012-01-01

    Heavy metals are the most common non-biodegradable pollutants. Various remediation methods have been used for the treatment of heavy metal contaminated water. However, phytoremediation technology is currently being used due to its economically feasible and ecologically viable advantages. The aim of this study was to examine the role of pH in the accumulation capacity of Lemna minor in Pb and Ni contaminated water. The removal rate of Pb and Ni from L. minor was 99.99% and 99.30% respectively,...

  19. 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.

  20. Erigeron bonariensis: hospedeira alternativa do Lettuce mosaic virus no Brasil

    Directory of Open Access Journals (Sweden)

    Chaves Alexandre L. R.

    2003-01-01

    Full Text Available O gênero Erigeron (Asteraceae, de plantas da vegetação espontânea, encontra-se amplamente disseminado nas regiões Sul e Sudeste do Brasil, sendo freqüentemente encontrado em lavouras perenes e anuais. Plantas de E. bonariensis com sintoma de mosaico, típico do induzido por vírus, foram coletadas no município de São Paulo e submetidas a análises ao microscópio eletrônico de transmissão, testes biológicos, sorológicos e moleculares. Em cortes ultrafinos do tecido foliar original, observaram-se inclusões tubulares e cata-ventos dispersos no citoplasma. Através de inoculação mecânica, somente Chenopodium amaranticolor, C. quinoa, Nicotiana benthamiana e N. clevelandii foram infetadas. Os resultados obtidos em ELISA foram negativos quando se utilizaram antissoros contra o Turnip mosaic vírus (TuMV e diferentes estirpes do Potato virus Y (PVY, constatando-se relacionamento sorológico com o Lettuce mosaic virus (LMV. Com a utilização de oligonucleotídeos específicos para LMV amplificaram-se fragmentos esperados de aproximadamente 280 pb, que seqüênciados confirmaram a identidade do vírus. A ocorrência do LMV em E. bonariensis, gênero da mesma família botânica da alface (Lactuca sativa, é de grande importância, pois talvez possa atuar como reservatório para infecção de campos de produção de alface. Este é o primeiro relato, no Brasil, de vírus infetando Erigeron sp., o qual só havia sido reportado como hospedeira natural do Bidens mottle virus (BiMoV e do Tomato spotted wilt virus (TSWV nos Estados Unidos.

  1. [Study of microbial contamination of processed fresh vegetables and lettuce].

    Science.gov (United States)

    efimochkina, N R; Bykova, I B; Batishcheva, S Iu; Minaeva, L P; Markova, Iu M; Korotkevich, Iu V; Shilov, G Iu; Sheveleva, S A

    2014-01-01

    Investigations of microbial contamination and species composition of the Enterobacteriaceae family in fresh vegetables and lettuce has been conducted. The objects of study were new types of fresh ready-to-eat vegetable foods - salads, sliced vegetables and mixtures thereof, sampled at the main stages of production, including washing, antimicrobial treatment with sodium hypochlorite, and packaging in the film under vacuum. Quantitative analysis of Enterobacteriaceae levels in fresh and packaged vegetables and salads showed that their part in the total amount of microbial contaminants is large enough. Average Enterobacteriaceae content ranged from 2,14 to 3,34 lg cfu/g, reaching in some samples values 4,38-4,74 lg, comparable with the levels of total bacteria. Considerable species diversity of microflora contaminating ready-to-eat vegetable products has been found. Bacteria of the genera Enterobactel; Pantoea, Citrobacter, Serratia, Pseudomonas, Kluyvera, Klebsiella, Escherichia, Rahnella, Acinetobacter were found in the salads and sliced vegetables. In the tested samples most frequently detected Enterobacter spp. - 37% of identified strains and Pantoea spp - 25% of strains. The data on the composition and levels of microbial contaminants in vegetable and salad products highlight not only the need to monitor coliform bacteria - traditional indicators of faecal contamination of raw materials, but also the need to introduce criteria for the amount of Enterobacteriaceae. PMID:25816624

  2. Qualidade microbiológica e produtividade de alface sob adubação química e orgânica / Microbiological quality and productivity of lettuce under chemical and organic fertilization

    Scientific Electronic Library Online (English)

    Ingergleice Machado de Oliveira, Abreu; Ana Maria Resende, Junqueira; José Ricardo, Peixoto; Sebastião Alberto de, Oliveira.

    2010-05-01

    Full Text Available A contaminação de hortaliças por micro-oganismos patogênicos é uma realidade. Os adubos orgânicos têm sido responsabilizados por algumas contaminações de hortaliças observadas no Brasil. O objetivo deste trabalho foi avaliar a produtividade e a contaminação de alface por Salmonella sp. e coliformes [...] a 45 °C, cultivada sob adubação orgânica. O delineamento experimental foi de blocos ao acaso, com seis tratamentos, em cinco repetições. Os tratamentos foram: T1 - Testemunha (sem adubação); T2 - Adubação química; T3 - Esterco de galinha; T4 - Esterco bovino; T5 - Húmus de minhoca; e T6 - Composto orgânico. As variáveis analisadas foram matéria fresca, matéria seca, macro e micronutrientes e contaminação microbiológica. Foi observada maior obtenção de matéria fresca nas parcelas adubadas com esterco de galinha (543 g), que diferiu estatisticamente da produção observada nos demais tratamentos. Não foi observada diferença estatística significativa entre tratamentos para matéria seca, com exceção da parcela com composto orgânico que apresentou o menor valor (3,7%). Não foi observada contaminação do solo e nem dos adubos orgânicos por esses micro-organismos. Porém, foi observada contaminação da água de irrigação e da alface por coliformes fecais. Existem fortes indícios de que a água de irrigação tenha sido o principal veículo de contaminação. Abstract in english Vegetable contamination with lethal microorganisms is a reality. Organic manure has been considered responsible for vegetable contamination in Brazil. The aim of this research was to evaluate the yield and lettuce contamination by Salmonella sp. and fecal coliforms, at 45 °C, grown under organic fer [...] tilization. The experimental design was in randomized blocks composed with 6 treatments in five replicates. The treatments were: T1 - Control (no fertilization); T2 - Chemical fertilization; T3 - Chicken manure; T4 - Cattle manure; T5 - Worm manure, and T6 - Organic compost. Fresh weight, dry matter percentage, macro and micronutrients, and microbiological contamination were recorded. The highest lettuce weight was observed in the parcels fertilized with chicken manure (543 g), which differed statistically from the weights observed in the other treatments. On the other hand, no statistical difference was observed in the dry matter percentage among the different treatments, with the exception of the value observed at the organic compost treatment, which was the lowest (3,7%). The soil and organic manure samples were not contaminated by Salmonella sp. and fecal coliforms. Nevertheless, irrigation water and lettuce samples were contaminated by fecal coliforms. There is strong evidence that irrigation water was the main source of lettuce contamination.

  3. Cooling and concentration of nutrient solution in hydroponic lettuce crop / Resfriamento e concentração da solução nutritiva em cultivo hidropônico da alface

    Scientific Electronic Library Online (English)

    Nilton N, Cometti; Diene M, Bremenkamp; Karla, Galon; Leonardo R, Hell; Marinaldo F, Zanotelli.

    2013-06-01

    Full Text Available O trabalho foi realizado em ambiente protegido, no setor de Horticultura do Instituto Federal do Espírito Santo, Campus Itapina, Colatina, região Noroeste do Espírito Santo, com o objetivo de estudar e avaliar o efeito do resfriamento e da condutividade elétrica da solução nutritiva no crescimento d [...] a alface cv. Vitória de Santo Antão em cultivo hidropônico. O trabalho foi realizado em delineamento experimental inteiramente casualizado com dois fatores (controle de temperatura máxima da solução nutritiva: 26ºC e sem controle; e condutividade elétrica (EC) da solução: 1, 2 e 3 dS m-1 e quatro repetições. Cinquenta e dois dias após a semeadura foi realizada a colheita das plantas e avaliados a massas frescas e secas de folha, caule e raiz, volume de raízes, comprimento do caule e das raízes e porcentagem de água nas plantas. A temperatura da solução nutritiva influenciou o desempenho da alface em função do aumento da condutividade elétrica, demonstrando que o aumento da EC não compromete a produtividade quando há limitação na temperatura máxima da solução nutritiva, que nesse experimento foi de 26ºC. O resfriamento da solução proporcionou maior acúmulo de massa e porcentagem superior de água presente nas plantas, aumentando a produtividade da alface hidropônica em condições de clima tropical. Abstract in english The study was conducted in greenhouse at horticulture department of the Instituto Federal do Espírito Santo, Campus Itapina, Colatina, northwestern Espírito Santo state, Brazil, with the objective of evaluating the effect of cooling and electrical conductivity of nutrient solution on growth and deve [...] lopment of lettuce cv. Vitória de Santo Antão in hydroponics. The study was conducted in a completely randomized design with two factors (control of the maximum temperature of the nutrient solution: 26ºC and without control; and electrical conductivity, EC, of the solution: 1, 2 and 3 dS m-1) with three repetitions. The plants were harvested fifty-two days after sowing (DAS). We evaluated the dry and fresh mass of leaves, stems and roots, stem and root length, root volume and plant water content (%). The temperature of the nutrient solution influenced the behavior of lettuce influenced by the electrical conductivity, showing that the increase of the EC did not reduce the lettuce productivity when the maximum temperature of the nutrient solution is limited, which in this experiment was tested at 26ºC. The cooling of the nutrient solution provided greater accumulation of mass and a higher water percentage in plants, increasing the productivity of hydroponic lettuce in tropical climate.

  4. Qualidade microbiológica e produtividade de alface sob adubação química e orgânica Microbiological quality and productivity of lettuce under chemical and organic fertilization

    Directory of Open Access Journals (Sweden)

    Ingergleice Machado de Oliveira Abreu

    2010-05-01

    Full Text Available A contaminação de hortaliças por micro-oganismos patogênicos é uma realidade. Os adubos orgânicos têm sido responsabilizados por algumas contaminações de hortaliças observadas no Brasil. O objetivo deste trabalho foi avaliar a produtividade e a contaminação de alface por Salmonella sp. e coliformes a 45 °C, cultivada sob adubação orgânica. O delineamento experimental foi de blocos ao acaso, com seis tratamentos, em cinco repetições. Os tratamentos foram: T1 - Testemunha (sem adubação; T2 - Adubação química; T3 - Esterco de galinha; T4 - Esterco bovino; T5 - Húmus de minhoca; e T6 - Composto orgânico. As variáveis analisadas foram matéria fresca, matéria seca, macro e micronutrientes e contaminação microbiológica. Foi observada maior obtenção de matéria fresca nas parcelas adubadas com esterco de galinha (543 g, que diferiu estatisticamente da produção observada nos demais tratamentos. Não foi observada diferença estatística significativa entre tratamentos para matéria seca, com exceção da parcela com composto orgânico que apresentou o menor valor (3,7%. Não foi observada contaminação do solo e nem dos adubos orgânicos por esses micro-organismos. Porém, foi observada contaminação da água de irrigação e da alface por coliformes fecais. Existem fortes indícios de que a água de irrigação tenha sido o principal veículo de contaminação.Vegetable contamination with lethal microorganisms is a reality. Organic manure has been considered responsible for vegetable contamination in Brazil. The aim of this research was to evaluate the yield and lettuce contamination by Salmonella sp. and fecal coliforms, at 45 °C, grown under organic fertilization. The experimental design was in randomized blocks composed with 6 treatments in five replicates. The treatments were: T1 - Control (no fertilization; T2 - Chemical fertilization; T3 - Chicken manure; T4 - Cattle manure; T5 - Worm manure, and T6 - Organic compost. Fresh weight, dry matter percentage, macro and micronutrients, and microbiological contamination were recorded. The highest lettuce weight was observed in the parcels fertilized with chicken manure (543 g, which differed statistically from the weights observed in the other treatments. On the other hand, no statistical difference was observed in the dry matter percentage among the different treatments, with the exception of the value observed at the organic compost treatment, which was the lowest (3,7%. The soil and organic manure samples were not contaminated by Salmonella sp. and fecal coliforms. Nevertheless, irrigation water and lettuce samples were contaminated by fecal coliforms. There is strong evidence that irrigation water was the main source of lettuce contamination.

  5. The sensitivity of an hydroponic lettuce root elongation bioassay to metals, phenol and wastewaters.

    Science.gov (United States)

    Park, Jihae; Yoon, Jeong-Hyun; Depuydt, Stephen; Oh, Jung-Woo; Jo, Youn-Min; Kim, Kyungtae; Brown, Murray T; Han, Taejun

    2016-04-01

    The root elongation bioassay is one of the most straightforward test methods used for environmental monitoring in terms of simplicity, rapidity and economy since it merely requires filter paper, distilled water and Petri dishes. However, filter paper as a support material is known to be problematic as it can reduce the sensitivity of the test. The newly developed hydroponic method reported here differs from the conventional root elongation method (US EPA filter paper method) in that no support material is used and the exposure time is shorter (48h in this test versus 120h in the US EPA test). For metals, the hydroponic test method was 3.3 (for Hg) to 57 (for Cu) times more sensitive than the US EPA method with the rank orders of sensitivity, estimated from EC50 values, being Cu?Cd>Ni?Zn?Hg for the former and Hg?Cu?Ni?Cd?Zn for the latter methods. For phenol, the results did not differ significantly; EC50 values were 124mgL(-1) and 108-180mgL(-1) for the hydroponic and filter paper methods, respectively. Lettuce was less sensitive than daphnids to wastewaters, but the root elongation response appears to be wastewater-specific and is especially sensitive for detecting the presence of fluorine. The new hydroponic test thus provides many practical advantages, especially in terms of cost and time-effectiveness requiring only a well plate, a small volume of distilled water and short exposure period; furthermore, no specialist expertise is required. The method is simpler than the conventional EPA technique in not using filter paper which can influence the sensitivity of the test. Additionally, plant seeds have a long shelf-life and require little or no maintenance. PMID:26748376

  6. Modeling the effect of solar radiation on dry matter accumulation in lettuce

    International Nuclear Information System (INIS)

    Dry matter production of lettuce plant in different seasons was studied quantitatively based on the amount of intercepted solar radiation by plant. (1) Top dry weight was a linear function of the total amount of intercepted solar radiation by plant and the relationship between the two parameters did not differ between seasons. Daily dry matter increase (delta-DW) mainly depended on the daily amount of intercepted solar radiation by plant (DIR) and radiation-sue efficiency (RUE; the ratio of the amount of dry matter production to the amount of intercepted solar radiation) was considered to be almost constant throughout the growth period in every experiment. (2) DIR could be resolved into daily amount of solar radiation and effective area (A), modified vertically projected area of plant (VPA) with planting density and light absorptivity of plant. A simple model which calculated A with VPA was developed. This model indicated that delta-DW is influenced proportional by VPA until VPA reaches the area given as the product of row interval and plant interval and there after the VPA increase does not exert any additional effect on the productivity. (3) a simple model for calculating A with top dry weight was also developed. This model used different parameters between seasons because of the difference in the relationship of VPA and top dry weight between seasons. This model indicated that at the early growth stage, A value per top dry weight in winter was lower than that in autumn but that A reached almost the same level in both seasons. (4) Differences in delta-DW due to season could be attributed to the difference in solar radiation and VPA. Negligible difference in VPA per top fresh weight between seasons and low water content of top in winter suggested that suppressed water uptake due to low temperature may result in low VPA in winter

  7. 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. PMID:25098494

  8. Changes in the metabolome of lettuce leaves due to exposure to mancozeb pesticide.

    Science.gov (United States)

    Pereira, Sara I; Figueiredo, Patricia I; Barros, António S; Dias, Maria C; Santos, Conceição; Duarte, Iola F; Gil, Ana M

    2014-07-01

    This paper describes a proton high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) metabolomic study of lettuce (Lactuca sativa L.) leaves to characterise metabolic adaptations during leaf growth and exposure to mancozeb. Metabolite variations were identified through multivariate analysis and checked through spectral integration. Lettuce growth was accompanied by activation of energetic metabolism, preferential glucose use and changes in amino acids, phospholipids, ascorbate, nucleotides and nicotinate/nicotinamide. Phenylalanine and polyphenolic variations suggested higher oxidative stress at later growth stages. Exposure to mancozeb induced changes in amino acids, fumarate and malate, suggesting Krebs cycle up-regulation. In tandem disturbances in sugar, phospholipid, nucleotide and nicotinate/nicotinamide metabolism were noted. Additional changes in phenylalanine, dehydroascorbate, tartrate and formate were consistent with a higher demand for anti-oxidant defence mechanisms. Overall, lettuce exposure to mancozeb was shown to have a significant impact on plant metabolism, with mature leaves tending to be more extensively affected than younger leaves. PMID:24518345

  9. Host-induced gene silencing inhibits the biotrophic pathogen causing downy mildew of lettuce.

    Science.gov (United States)

    Govindarajulu, Manjula; Epstein, Lynn; Wroblewski, Tadeusz; Michelmore, Richard W

    2015-09-01

    Host-induced gene silencing (HIGS) is an RNA interference-based approach in which small interfering RNAs (siRNAs) are produced in the host plant and subsequently move into the pathogen to silence pathogen genes. As a proof-of-concept, we generated stable transgenic lettuce plants expressing siRNAs targeting potentially vital genes of Bremia lactucae, a biotrophic oomycete that causes downy mildew, the most important disease of lettuce worldwide. Transgenic plants, expressing inverted repeats of fragments of either the Highly Abundant Message #34 (HAM34) or Cellulose Synthase (CES1) genes of B. lactucae, specifically suppressed expression of these genes, resulting in greatly reduced growth and inhibition of sporulation of B. lactucae. This demonstrates that HIGS can provide effective control of B. lactucae in lettuce; such control does not rely on ephemeral resistance conferred by major resistance genes and therefore offers new opportunities for durable control of diverse diseases in numerous crops. PMID:25487781

  10. 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.

  11. Biogeography of the Pistia clade (Araceae)

    OpenAIRE

    Renner, Susanne S; Zhang, Li-Bing

    2004-01-01

    Pistia stratiotes (water lettuce) and Lemna (duckweeds) are the only free-floating aquatic Araceae. The geographic origin and phylogenetic placement of these unrelated aroids present long-standing problems because of their highly modified reproductive structures and wide geographical distributions. We sampled chloroplast (trnL-trnF and rpl20-rpsl2 spacers, trnL intron) and mitochondrial sequences (nadl b/c intron) for all genera implicated as close relatives of Pistia by morphological, restri...

  12. 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. PMID:26685781

  13. Ocorrência generalizada do Lettuce mottle virus em três regiões produtoras de alface comercial do Estado de São Paulo Occurrence of Lettuce mottle virus on three lettuce producing areas from São Paulo State

    Directory of Open Access Journals (Sweden)

    Renate Krause-Sakate

    2008-02-01

    Full Text Available Os sequivírus são vírus isométricos transmitidos por afídeos. Lettuce mottle virus (LeMoV, um provável sequivirus foi descrito no Brasil em 1982 e causa sintomas de mosaico semelhantes aos observados pelo Lettuce mosaic virus (LMV. Um levantamento para ocorrência do LeMoV nos campos de produção de alface de três diferentes regiões do Estado de São Paulo (Mogi das Cruzes, Campinas e Bauru foi realizado durante 2002 a 2005. RNA total foi extraído e utilizado na detecção, em RT-PCR, com oligonucleotídeos específicos para o LeMoV. Do total de 1362 amostras, 137 (10,05% foram positivas para o LeMoV. Infecção mista com o LMV foi verificada em 43 amostras (31,4%. Foi verificada a ocorrência do LeMoV nas três diferentes regiões analisadas, porém sua ocorrência foi baixa nas diferentes épocas do ano.Sequiviruses are isometric aphid-borne plant viruses. Lettuce mottle virus (LeMoV, a putative sequivirus was first described in Brazil on 1982 causing similar mosaic symptoms as Lettuce mosaic virus (LMV. A survey for the occurrence of LeMoV on open field conditions was carried out during 2002 to 2005 on Mogi das Cruzes, Campinas and Bauru in São Paulo state. Total RNA was extracted and used on RT-PCR with specific LeMoV primers. On 1362 samples tested, 137 (10,05% were positive for LeMoV. Mixed infections with LMV was observed on 43 samples (31,4%. The presence of LeMoV was observed in the three different regions, but with low incidence during the year.

  14. Alelopatia de extratos de diferentes órgãos de mulungu na germinação de alface / Allelopathy of extracts of different organs of coral tree on the germination of lettuce

    Scientific Electronic Library Online (English)

    Andreya K, Oliveira; Maria de Fatima B, Coelho; Sandra Sely S, Maia; Francisco EP, Diógenes; Sebastião, Medeiros Filho.

    2012-09-01

    Full Text Available O mulungu (Erythrina velutina) é uma árvore de crescimento rápido, com propriedades medicinais. O objetivo no presente trabalho foi avaliar o efeito alelopático do extrato aquoso de sementes, flores e cascas de mulungu na germinação e desenvolvimento de plântulas de alface cv. Mônica SF FI. O deline [...] amento experimental utilizado foi inteiramente casualizado com sete tratamentos [extrato de sementes a 100°C, extrato de sementes a 25°C, extrato de cascas a 100°C, extrato de cascas a 25°C, extrato de flores a 100°C, extrato de flores a 25°C e água destilada (testemunha)] com quatro repetições. Os extratos obtidos de sementes, independente da temperatura de extração reduziram a porcentagem e velocidade de germinação de sementes de alface e afetaram o desenvolvimento das plântulas. Os demais extratos não afetaram a germinação, mas causaram o aparecimento de plântulas anormais e mortas. Os extratos aquosos de sementes de mulungu têm potencial alelopático sobre as sementes de alface cv. Mônica SF FI. Abstract in english The coral tree (Erythrina velutina) is a fast growing tree with medicinal properties. The aim of this study was to evaluate the allelopathic effects of aqueous extract of seeds, flowers and bark of coral tree on seed germination and seedling development of lettuce cv. Mônica SF FI. The experimental [...] design was completely randomized with seven treatments [seed extract at 100°C, seed extract at 25°C, bark extract at 100°C, bark extract at 25°C, flower extract at 100°C, flower extract at 25°C and distilled water (control)] with four replications. The extracts of seeds, independent of the extraction temperature decreased the percentage and speed of germination of lettuce and affected the development of the seedlings. The other extracts did not affect germination, but caused the appearance of abnormal seedlings and dead. The aqueous extract of seeds of coral tree has allelopathic potential in the seeds of lettuce cv. Mônica SF FI.

  15. Impacts of major cations (K(+), Na (+), Ca (2+), Mg (2+)) and protons on toxicity predictions of nickel and cadmium to lettuce (Lactuca sativa L.) using exposure models.

    Science.gov (United States)

    Liu, Yang; Vijver, Martina G; Peijnenburg, Willie J G M

    2014-04-01

    Biotic ligand models (BLM) explicitly accounting for hypothetical interactions with biotic ligands and bioavailability as dictated by water chemistry have been developed for various metals and different organisms. It is only recently that BLMs for plants have received increasing attention. Lettuce is one of the most important vegetable crops in the world. This study investigated the impacts of Ca(2+), Mg(2+), K(+), Na(+) and pH, on acute toxicity of Ni and Cd to butter-head lettuce seedlings (Lactuca sativa L.). 4-day assays with the root elongation inhibition (REI) as the endpoint were performed in hydroponic solutions. Magnesium was found to be the sole cation significantly enhancing the median inhibition concentration (IC50) of Ni(2+) with increasing concentration. By incorporating the competitive effects of Mg(2+), the Ni-toxicity prediction was improved significantly as compared to the total metal model (TMM) and the free ion activity model (FIAM). The conditional stability constants derived from the Ni-BLM were log K MgBL = 2.86, log K NiBL = 5.1, and f NiBL (50%)  = 0.57. A slight downtrend was observed in the 4-d IC50 of Cd(2+) at increasing H(+) concentrations, but this tendency was not consistent and statistically significant (p = 0.07) over the whole range. The overall variations of Cd-toxicity within the tested Na(+), K(+), Ca(2+) and Mg(2+) concentration ranges were relatively small and not statistically significant. 80 % of lettuce REI by Cd could be explained using both TMM and FIAM instead of BLM in the present study. Thus, the mechanistically underpinned models for soil quality guidelines should be developed on a metal-specific basis across different exposure conditions. PMID:24510448

  16. 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.

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

    International Nuclear Information System (INIS)

    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

  18. Analysis of ADP-glucose pyrophosphorylase expression during turion formation induced by abscisic acid in Spirodela polyrhiza (greater duckweed

    Directory of Open Access Journals (Sweden)

    Wang Wenqin

    2012-01-01

    Full Text Available Abstract Background Aquatic plants differ in their development from terrestrial plants in their morphology and physiology, but little is known about the molecular basis of the major phases of their life cycle. Interestingly, in place of seeds of terrestrial plants their dormant phase is represented by turions, which circumvents sexual reproduction. However, like seeds turions provide energy storage for starting the next growing season. Results To begin a characterization of the transition from the growth to the dormant phase we used abscisic acid (ABA, a plant hormone, to induce controlled turion formation in Spirodela polyrhiza and investigated their differentiation from fronds, representing their growth phase, into turions with respect to morphological, ultra-structural characteristics, and starch content. Turions were rich in anthocyanin pigmentation and had a density that submerged them to the bottom of liquid medium. Transmission electron microscopy (TEM of turions showed in comparison to fronds shrunken vacuoles, smaller intercellular space, and abundant starch granules surrounded by thylakoid membranes. Turions accumulated more than 60% starch in dry mass after two weeks of ABA treatment. To further understand the mechanism of the developmental switch from fronds to turions, we cloned and sequenced the genes of three large-subunit ADP-glucose pyrophosphorylases (APLs. All three putative protein and exon sequences were conserved, but the corresponding genomic sequences were extremely variable mainly due to the invasion of miniature inverted-repeat transposable elements (MITEs into introns. A molecular three-dimensional model of the SpAPLs was consistent with their regulatory mechanism in the interaction with the substrate (ATP and allosteric activator (3-PGA to permit conformational changes of its structure. Gene expression analysis revealed that each gene was associated with distinct temporal expression during turion formation. APL2 and APL3 were highly expressed in earlier stages of turion development, while APL1 expression was reduced throughout turion development. Conclusions These results suggest that the differential expression of APLs could be used to enhance energy flow from photosynthesis to storage of carbon in aquatic plants, making duckweeds a useful alternative biofuel feedstock.

  19. Índices morfofisiológicos e de produção de alface sob estresse salino / Morphophysiological indices and production of lettuce under saline stress

    Scientific Electronic Library Online (English)

    Sergio B. A., Viana; Pedro D., Fernandes; Hans R., Gheyi; Frederico A. L., Soares; Paulo T., Carneiro.

    2004-04-01

    Full Text Available No Nordeste brasileiro, a alface é uma importante olerícola cultivada sob condições de irrigação em que são utilizadas águas de qualidade variada; uma das características da região é a variação espacial e temporal da qualidade dos recursos hídricos. Mesmo assim, são escassos os trabalhos referentes [...] aos efeitos da salinidade na formação de mudas e seu reflexo sobre a produção. Neste trabalho estudaram-se os efeitos de cinco níveis de condutividade elétrica da água de irrigação (CEa: 0,3, 1,0, 1,7, 2,4 e 3,1 dS m-1), em relação aos índices morfofisiológicos da alface 'Elba', a partir de mudas produzidas com águas de 0,3 e 3,1 dS m-1. Não houve efeito interativo entre os fatores estudados. O índice raiz/parte-aérea e a taxa de crescimento absoluto, foram afetados pela CEa, mas sem efeito sobre a taxa de crescimento relativo. O crescimento das plantas, cujas mudas foram produzidas com CEa de 3,1 dS m-1, foi inferior no início do ciclo, recuperando-se paulatinamente durante o crescimento; no momento da colheita, as taxas de crescimento absoluto e relativo foram, respectivamente, iguais e superiores às das plantas produzidas com água de baixa salinidade. A evapotranspiração diminuiu com o aumento da salinidade. As relações Na+/(Ca2++Mg2+) e Na+/K+ em folhas foram incrementadas linearmente com a salinidade, mas as plantas conseguiram manter o balanço iônico favorável. O rendimento da alface diminuiu 6,1 e 9,0% por aumento unitário de condutividade elétrica do extrato de saturação do solo e da água de irrigação, acima de 0,3 e 1,73 dS m-1, respectivamente. Abstract in english Lettuce is an important vegetable crop in the Northeast of Brazil cultivated under irrigated conditions using water of variable quality; one of the characteristics of this region is spatial and temporal variation in quality of water resources. In spite of this, research related to effects of salinit [...] y on the seedling formation and its posterior reflex on production is limited. In the present study, the effects of salinity of irrigation water (ECw: 0.3, 1.0, 1.7, 2.4 and 3.1 dS m-1) on growth response of lettuce 'Elba' using two types of seedlings produced with ECw of 0.3 and 3.1 dS m-1 were evaluated in a greenhouse. The studied factors had no interactive effect. Root/shoot ratio and absolute growth rate were affected by salinity although relative growth rate was not affected directly. The seedlings produced with ECw of 3.1 dS m-1 had lower growth rates at the beginning but recovered gradually during the growth cycle. In the last evaluation, the absolute and relative growth rates of these plants were, respectively, equal and superior to that of plants produced with water of low salinity. Increasing water salinity decreased evapotranspiration. The Na+/(Ca2++Mg2+) and Na+/K+ ratios in leaf increased linearly with the salinity but plants maintained favorable ionic balance. The decrease in lettuce yield was 6.1 and 9.0% per unit increase in electrical conductivity of the saturation extract of soil and of irrigation water above 0.3 and 1.73 dS m-1, respectively.

  20. Estimation of water turnover rates of captive West Indian manatees (Trichechus manatus) held in fresh and salt water

    Science.gov (United States)

    Ortiz, R. M.; Worthy, G. A.; Byers, F. M.

    1999-01-01

    The ability of West Indian manatees (Trichechus manatus) to move between fresh and salt water raises the question of whether manatees drink salt water. Water turnover rates were estimated in captive West Indian manatees using the deuterium oxide dilution technique. Rates were quantified in animals using four experimental treatments: (1) held in fresh water and fed lettuce (N=4), (2) held in salt water and fed lettuce (N=2), (3) acutely exposed to salt water and fed lettuce (N=4), and (4) chronically exposed to salt water with limited access to fresh water and fed sea grass (N=5). Animals held in fresh water had the highest turnover rates (145+/-12 ml kg-1 day-1) (mean +/- s.e.m.). Animals acutely exposed to salt water decreased their turnover rate significantly when moved into salt water (from 124+/-15 to 65+/-15 ml kg-1 day-1) and subsequently increased their turnover rate upon re-entry to fresh water (146+/-19 ml kg-1 day-1). Manatees chronically exposed to salt water had significantly lower turnover rates (21+/-3 ml kg-1 day-1) compared with animals held in salt water and fed lettuce (45+/-3 ml kg-1 day-1). Manatees chronically exposed to salt water and fed sea grass had very low turnover rates compared with manatees held in salt water and fed lettuce, which is consistent with a lack of mariposia. Manatees in fresh water drank large volumes of water, which may make them susceptible to hyponatremia if access to a source of Na+ is not provided.

  1. Study of atmospheric tritium transfers in lettuce: kinetic study, equilibrium and organic incorporation during a continuous atmospheric exposure

    International Nuclear Information System (INIS)

    This thesis has explored the mechanisms of tritium 'absorption and incorporation in a human-consumed plant, lettuce (Lactuca sativa L.), due to atmospheric exposure. Foliar uptake appears to play a key role in absorption of tritium as tissue free water tritium. Whatever the development stage and the light conditions, the specific activity in tissue free water reaches that of water vapour in air in several hours. The specific activity ratio is then about 0, 4. The time to reach equilibrium in soil is over 24 hours in most cases: the specific activity ratio ranges then 0, 01 to 0, 26. Incorporation rate of tissue free water tritium as organically-bound tritium has been estimated to 0, 13 to 0, 16 % h-l in average over the growing period of the plant, but marked variations are observed during growth. In particular, a significant increase appeared at the exponential growth stage. Deposition and diffusion of tritium in soil lead to significant OBT activities in soil. Results globally indicate equilibrium between the different environmental compartments (air, soil, plant). However, some experiments have revealed high OBT concentrations regarding atmospheric level exposure and ask for a possible phenomenon of local tritium accumulation in OBT for particular conditions of exposure. (author)

  2. Avaliação patogênica in vitro de Pythium middletonii Sparrow e Pythium dissotocum Drechsler em alface / In vitro pathogenic evaluation of Pythium middletonii Sparrow and Pythium dissotocum Drechsler in lettuce

    Scientific Electronic Library Online (English)

    F.R., Baptista; C.L.A, Pires-Zottarelli; L.D., Teixeira; N.A., Santos Júnior.

    2011-03-01

    Full Text Available Infecções radiculares nos cultivos hidropônicos de alface são frequentes e, na maior parte das vezes, causadas por espécies de Pythium, extremamente bem adaptadas ao ambiente aquático. Este estudo buscou avaliar o potencial patogênico in vitro de Pythium middletonii e P. dissotocum, em quatro cultiv [...] ares de alface: Elisa (lisa), Vera (crespa), Mimosa (mimosa) e Tainá (americana). Sementes de alface, de cada cultivar, foram desinfetadas superficialmente, pré-germinadas por 24 horas, e colocadas na superfície do meio ágar-água. Em seguida, um disco de micélio dos isolados de Pythium, foi disposto no centro de cada placa. Placas contendo apenas as sementes de alface serviram como controle. O delineamento experimental utilizado foi inteiramente casualizado, com cinco repetições, sendo cada uma delas representada por uma placa de Petri. Avaliou-se o comprimento dos hipocótilos, das radículas e a porcentagem das plântulas sobreviventes após dez dias de incubação. O experimento foi conduzido na temperatura ideal de crescimento da alface (20ºC), e nas ideais para o crescimento dos isolados, 23ºC para P. middletonii e 27ºC para P. dissotocum. A 20ºC, P. dissotocum foi mais patogênico que P. middletonii, reduzindo significativamente o comprimento dos hipocótilos e, principalmente, das radículas, de praticamente todas as cultivares. Na temperatura de 27ºC, P. dissotocum foi responsável pela mais baixa porcentagem de plântulas sobreviventes entre as cultivares, sendo mais patogênico em Vera (54% de sobrevivência). Dentre as cultivares analisadas, a Mimosa mostrou tendência de menor suscetibilidade a este patógeno, apresentando a maior porcentagem de plântulas sobreviventes e o maior comprimento das radículas em relação ao controle. P. dissotocum apresentou maior crescimento micelial e foi mais patogênico que P. middletonii em todos os experimentos realizados. Abstract in english Root infections in hydroponic lettuce are frequent and mostly caused by Pythium species, which are extremely well adapted to aquatic environments. The present study aimed to evaluate in vitro the pathogenic potential of Pythium middletonii and Pythium dissotocum in four cultivars of lettuce, Elisa ( [...] smooth), Vera (curly), Mimosa (mimosa) and Tainá (American). Lettuce seeds from each cultivar were superficially disinfected, pre-germinated for 24 hours and placed on the water agar medium surface. Then, a dish containing mycelium from Pythium isolates was placed in the center of each plate. Control consisted of plates containing lettuce seeds only. Experimental design was completely randomized, with five replicates, each one represented by a Petri dish. Hypocotyl and radical length besides surviving seedlings percentage after ten days of incubation were evaluated. The experiment was carried out, at different temperatures, and the pathogenicity of the isolates was investigated at the ideal temperature for the lettuce (20ºC), and at the ideal temperatures for the growth of the isolates, 23ºC for P. middletonii and 27ºC for P. dissotocum. At 20ºC, P. dissotocum had higher pathogenicity on lettuce cultivars than P. middletonii, significantly decreasing the length of hypocotyls, especially radicles, of most cultivars. For P. dissotocum, 27ºC was the most suitable temperature for the specimen growth; however, it led to the lowest percentage of surviving seedlings among all cultivars, with the lowest percentage (54%) detected for Vera. Among the cultivars, Mimosa presented higher percentage of survivor seedlings and higher length of radicles in relation to the control, and thus was considered less susceptible to the pathogen. P. dissotocum presented higher mycelium growth and was more pathogenic than P. middletonii in all experiments.

  3. Active packaging for fresh-cut iceberg lettuce (Lactuca sativa L. / Embalagem ativa para alface americana (Lactuca sativa L. minimamente processada

    Directory of Open Access Journals (Sweden)

    Fábio Yamashita

    2010-09-01

    Full Text Available The minimal processing of horticultural products endears the raw material and is convenient to the consumer due to the facility for preparing and consuming. The objective of this work was to develop an active packaging for fresh-cut iceberg lettuce (Lactuca sativa L. to increase its shelf life. Minimally processing methodology was defined and the product quality was determined by sensorial, physico-chemical and microbiological analysis. The lettuce tree was selected, trimmed, pre-washed, soaked in sanitized water (100ppm of active chlorine for 15 minutes and centrifuged. The lettuce leafs were packed in polypropylene pots with a sachet containing 1-methylcyclopropene (1-MCP and sealed with biodegradable starch film. Soon after the processing, the product was stored at 4oC for 12 days. Periodically samples were evaluated in terms of appearance and purchase intention, soluble solids and vitamin C contents, pH, texture, color, weight loss and total count of mesophilic and psicotrofic microorganisms, lactic bacteria, mould and yeast. Using 1-MCP in sachet format did not increase the lettuce shelf life but the minimal processing combined with packaging sealed with biodegradable film is practicable as the product showed good sensorial acceptance, low microbiological counts and shelf life of 5 days at 4oC.O processamento mínimo de produtos hortícolas agrega valor à matéria-prima e são convenientes ao consumidor, devido à facilidade de preparo e consumo. O objetivo do trabalho foi desenvolver uma embalagem ativa para alface americana (Lactuca sativa L. minimamente processada visando o aumento da vida útil. Foi definida uma metodologia de processamento mínimo e a qualidade do produto foi acompanhada através de avaliação sensorial, físico-química e microbiológica. As cabeças de alface foram desfolhadas, selecionadas, pré-lavadas, sanificadas (100 ppm de cloro ativo por 15 minutos e centrifugadas. As folhas foram acondicionadas em potes de polipropileno contendo sachês com 1-metilciclopropeno (1-MCP e seladas com filme biodegradável de amido. Logo após o processamento, o produto foi armazenado a 4ºC por 12 dias. Periodicamente amostras foram avaliadas sensorialmente (aparência e intenção de compra e foram determinados os teores de sólidos solúveis e vitamina C, pH, textura, cor, perda de massa e contagem total de microrganismos mesófilos, psicrotróficos, bactérias láticas, bolores e leveduras. O uso de 1-MCP na forma de sachê não aumentou a vida útil da alface em relação ao controle, mas o processamento mínimo associado à embalagem selada com filme biodegradável é uma técnica viável, pois o produto apresentou boa aceitação sensorial, contaminação microbiológica baixa e vida de prateleira de 5 dias a 4oC.

  4. Condutividade elétrica da solução nutritiva e produção de alface em hidroponia Electrical conductivity of nutrient solution and hidroponic crisp head lettuce yield

    Directory of Open Access Journals (Sweden)

    Paulo César Costa

    2001-09-01

    Full Text Available A variação da condutividade elétrica da solução nutritiva altera a absorção de água e nutrientes pelas plantas, interferindo no metabolismo e, consequentemente, na produção das mesmas. Este trabalho, conduzido no período de agosto a outubro de 1999, avaliou o efeito da condutividade elétrica (CE sobre a produção e desenvolvimento de alface americana de cabeça crespa, cultivar Ryder em hidroponia. As tendências de variação da condutividade elétrica do meio nutritivo, durante o desenvolvimento da alface, foram também avaliadas. Foi utilizado o delineamento inteiramente casualizado com seis repetições e três tratamentos, constituídos pelas condutividade elétricas: CE1= 1,46, CE2= 2,46 e CE3= 4,21 (± 0,24 mS cm-1. O diâmetro e altura da cabeça e peso seco da raiz não foram influenciados pelas condutividades elétricas da solução nutritiva. Os maiores pesos do material fresco e seco foram conseguidos com CE 2,46 (± 0,24 mS cm-1. Todos os tratamentos apresentaram a tendência de diminuição da condutividade elétrica, durante o cultivo da alface verificando-se que a condutividade elétrica teve influência sobre as características de produção da alface americana.The levels of electrical conductivity (EC can alter water and nutrient uptake by plants, influencing their metabolism and yield. This experiment was carried out to verify the effects of EC on the yield and the development of the crisp head lettuce cv. Ryder in hidroponics. The tendency of the electrical conductivity changes of the nutrient solution during the development of the lettuce was also evaluated. A completely randomized design was used, with six replications and three treataments: EC1= 1.46, EC2= 2.46 and EC3= 4.21 (± 0.24 mS cm-1. Lettuce head diameter and height, and root dry weight were not influenced by EC. The largest fresh and dry weights of heads were obtained for 2.46 (± 0.24 mS cm-1. All treatments had the same tendency of reducing EC during lettuce growth.

  5. Avaliação da reação de genótipos de alface (Lactuca sativa L.) ao Lettuce mosaic virus (LMV) / Reaction of Lactuca sativa L. lines to Lettuce mosaic virus (LMV)

    Scientific Electronic Library Online (English)

    Rosa Maria, Chung; Joaquim Adelino de, Azevedo Filho; Addolorata, Colariccio.

    Full Text Available O trabalho teve como meta avaliar a reação de 18 linhagens superiores do programa de melhoramento de alface (Lactuca sativa L.) do IAC e de seis cultivares comerciais, ao Lettuce mosaic virus (LMV). Em condições de campo, na região de Atibaia (SP), foram observados sintomas de mosaico, nanismo e nec [...] rose em plantas das cultivares Rider, 'Karla H25' e Hortência. O vírus presente nos isolados foi identificado por meio de inoculação mecânica em plantas indicadoras e diferenciadoras e de testes sorológicos de Plate Trapped Antigen-Enzyme linked-immunosorbent assay (PTA-ELISA). Nas amostras avaliadas, identificou-se a espécie LMV pelo PTA-ELISA e do patotipo IV pela reação nas hospedeiras diferenciais. Para a avaliação do comportamento dos genótipos de alface, foi empregado o LMV isolado 'Karla H25'. Foram submetidos à inoculação 24 genótipos de alface empregando-se, como controle positivo, a alface 'White Boston' por sua suscetibilidade ao LMV. O delineamento experimental foi inteiramente ao acaso e analisado pelo teste do qui-quadrado. Detectaram-se genótipos com comportamento de suscetibilidade e de tolerância. Nos genótipos 3 e 4, foram observadas plantas com comportamento de tolerância ao LMV isolado 'Karla H25', enquanto nos demais genótipos, constataram-se plantas com comportamento suscetível. O plantio de cultivares tolerantes pode ser uma alternativa aos prejuízos causados pela infecção pelo LMV com conseqüente diminuição do uso de produtos químicos para o controle dos afídeos vetores. Abstract in english Reactions to one isolate from diseased lettuce plants collected in 2003 in Atibaia, SP, were studied in six varieties and 18 selected lettuce (Lactuca sativa L.) lines. Underdeveloped, malformed leaves with mosaic symptoms and also necrotic leaves were found under field conditions in Raider, 'Karla [...] H25' and Hortência lettuce cultivars. These symptomatic plants were sampled and the virus etiology studied by PTA-ELISA and by means of mechanical inoculation on test plants and on differential lettuce cultivars resistant to Lettuce mosaic virus, LMV pathotypes I, II and III. LMV pathotype IV was identified in all cultivars studied by the reaction in the differential hosts. 'Karla H25'isolate was selected to screen the best lines of the breeding as well as lettuce program and commercial varieties. Twenty-four best lines of the program were inoculated with this isolate and the evaluations were based on symptoms. Symptomless lettuce plants were additionally tested for LMV presence, in PTA-ELISA, and by retro-inoculation to Chenopodium amaranticolor. The results indicated lines with varied degrees of susceptibility and tolerance. Lines 3 and 4 showed tolerance and this suggests that they can provide a good alternative for disease control and also that they might contribute in the reduction of chemical control.

  6. 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. PMID:18069080

  7. Tolerance of wheat and lettuce plants grown on human mineralized waste to high temperature stress

    Science.gov (United States)

    Ushakova, Sofya A.; Tikhomirov, Alexander A.; Shikhov, Valentin N.; Gros, Jean-Bernard; Golovko, Tamara K.; Dal'ke, Igor V.; Zakhozhii, Ilya G.

    2013-06-01

    The main objective of a life support system for space missions is to supply a crew with food, water and oxygen, and to eliminate their wastes. The ultimate goal is to achieve the highest degree of closure of the system using controlled processes offering a high level of reliability and flexibility. Enhancement of closure of a biological life support system (BLSS) that includes plants relies on increased regeneration of plant waste, and utilization of solid and liquid human wastes. Clearly, the robustness of a BLSS subjected to stress will be substantially determined by the robustness of the plant components of the phototrophic unit. The aim of the present work was to estimate the heat resistance of two plants (wheat and lettuce) grown on human wastes. Human exometabolites mineralized by hydrogen peroxide in an electromagnetic field were used to make a nutrient solution for the plants. We looked for a possible increase in the heat tolerance of the wheat plants using changes in photosynthetically active radiation (PAR) intensity during heat stress. At age 15 days, plants were subjected to a rise in air temperature (from 23 ± 1 °C to 44 ± 1 °?) under different PAR intensities for 4 h. The status of the photosynthetic apparatus of the plants was assessed by external ??2 gas exchange and fluorescence measurements. The increased irradiance of the plants during the high temperature period demonstrated its protective action for both the photosynthetic apparatus of the leaves and subsequent plant growth and development. The productivity of the plants subjected to temperature changes at 250 W m-2 of PAR did not differ from that of controls, whereas the productivity of the plants subjected to the same heat stress but in darkness was halved.

  8. Effects of different nutrients solutions on nutrients concentration and some qualitative traits of lettuce in hydroponics system

    Directory of Open Access Journals (Sweden)

    M. Safaei

    2015-08-01

    Full Text Available Lettuce (Lactuca sativa L., as a leafy vegetable, has considerable economic benefits. Although nowadays the tendency is to grow lettuce hydroponically, growers use different nutrients solutions for lettuce production and there is not an optimal nutrients solution for lettuce production in Iran. Therefore, an experiment was carried out to introduce the optimal solution out of current solutions in the market for lettuce production. In this experiment, effects of four nutrients solutions (Hoagland and Arnon, NSHoag; Knop’s, NSKnop, England, NSUK, and University of Tabriz solution, NSUT on two cultivars of lettuce (Siahoo and Conquistador were assessed. The experiment was conducted as a completely randomized blocks design with four replications at Faculty of Agriculture, University of Tabriz, Iran, and traits such as total soluble solids (TSS, panel test, percentage of leaf dry matter and leaf nitrogen, potassium, phosphorus, calcium and nitrate contents were assessed. Results showed that different nutrients solutions had significant effect on nutrients concentration and some of the qualitative characteristics of lettuce. The highest percentage of dry mater, leaf nitrogen and potassium content, were observed in Knop’s, UT and Hoagland solutions, respectively. Interaction between cultivar and nutrients solution became significant on panel test results. Hoagland and Knop’s solutions in Conquistador cultivar and England and Hoagland solutions in Siahoo cultivar showed maximum panel-test results. Nutrients solutions didn’t have significant effects on other traits. Therefore, it is concluded that Hoagland nutrients solution was the best solution for qualitative traits in lettuce production. But, it is necessary to analyze these nutrients solutions for lettuce yield and economic aspects.

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

    International Nuclear Information System (INIS)

    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. O2 levels in the packages of fresh-cut Iceberg lettuce decreased and CO2 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 O2 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.

  10. TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

    Directory of Open Access Journals (Sweden)

    Julián Andrés Rengifo-Herrera

    2010-01-01

    Full Text Available In this work, TiO2 photocatalysis was used to disinfect domestic wastewaters previously treated by different biological treatment systems: Upward-flow Anaerobic Sludge Blanket (UASB, facultative pond, and duckweed pond. The microorganisms monitored were E. coli, total coliforms, Shigella species, and Salmonella species. Photocatalytic experiments were carried out using two light sources: a solar simulator (UV intensity: 68-70 W m-2 and black-light lamps (BLL UV intensity: 17-20 W m-2. Samples were taken after each treatment stage. Results indicate that bacterial photocatalytic inactivation is affected by characteristics of the effluent, including turbidity, concentration of organic matter, and bacterial concentration, which depend of the type of biological pretreatment previously used.

  11. TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

    Scientific Electronic Library Online (English)

    Julián Andrés, Rengifo-Herrera; Cesar, Pulgarin; Fiderman, Machuca; Janeth, Sanabria.

    Full Text Available In this work, TiO2 photocatalysis was used to disinfect domestic wastewaters previously treated by different biological treatment systems: Upward-flow Anaerobic Sludge Blanket (UASB), facultative pond, and duckweed pond. The microorganisms monitored were E. coli, total coliforms, Shigella species, a [...] nd Salmonella species. Photocatalytic experiments were carried out using two light sources: a solar simulator (UV intensity: 68-70 W m-2) and black-light lamps (BLL UV intensity: 17-20 W m-2). Samples were taken after each treatment stage. Results indicate that bacterial photocatalytic inactivation is affected by characteristics of the effluent, including turbidity, concentration of organic matter, and bacterial concentration, which depend of the type of biological pretreatment previously used.

  12. Key mutations in the cylindrical inclusion involved in lettuce mosaic virus adaptation to eIF4E-mediated resistance in lettuce.

    Science.gov (United States)

    Sorel, M; Svanella-Dumas, L; Candresse, T; Acelin, G; Pitarch, A; Houvenaghel, M C; German-Retana, S

    2014-09-01

    We previously showed that allelic genes mol¹ and mo1² used to protect lettuce crops against Lettuce mosaic virus (LMV) correspond to mutant alleles of the gene encoding the eukaryotic translation initiation factor 4E. LMV resistance-breaking determinants map not only to the main potyvirus virulence determinant, a genome-linked viral protein, but also to the C-terminal region of the cylindrical inclusion (CI), with a key role of amino acid at position 621. Here, we show that the propagation of several non-lettuce isolates of LMV in mo1¹ plants is accompanied by a gain of virulence correlated with the presence in the CI C terminus of a serine at position 617 and the accumulation of mutations at positions 602 or 627. Whole-genome sequencing of native and evolved isolates showed that no other mutation could be associated with adaptation to mo1 resistance. Site-directed mutagenesis pinpointed the key role in the virulence of the combination of mutations at positions 602 and 617, in addition to position 621. The impact of these mutations on the fitness of the virus was evaluated, suggesting that the durability of mo1 resistance in the field relies on the fitness cost associated with the resistance-breaking mutations, the nature of the mutations, and their potential antagonistic effects. PMID:25105805

  13. Kinetics of basic dye (methylene blue) biosorption by giant duckweed (Spirodela polyrrhiza)

    Energy Technology Data Exchange (ETDEWEB)

    Waranusantigul, P.; Pokethitiyook, P.; Kruatrachue, M.; Upatham, E.S

    2003-10-01

    Sorbent dosage, pH and contact time were evaluated as factors affecting dye uptake by Spirodela polyrrhiza. - Wastewater containing pigments and/or dyes can cause serious water pollution problems in the form of reduced light penetration and photosynthesis, and the toxicity from heavy metals associated with pigments and/or dyes. Laboratory investigations, of the potential use of dried Spirodela polyrrhiza biomass as an adsorbent for the removal of the basic dye methylene blue from aqueous solution were conducted. A series of experiments were undertaken in an agitated batch adsorber to assess the effect of the system variables, i.e. sorbent dosage, pH, and contact time. The results showed that as the amount of the dried S. polyrrhiza increased, the percentage of dye sorption increased accordingly. At pH 2.0 the sorption of dye was not favorable, while the sorption at other pHs (3.0-11.0) was remarkable. There was no significant difference in the dye concentration remaining when the pH was increased from 3.0 to 11.0. The dye removal time was influenced by the initial dye concentration, and the process followed the first-order rate kinetics. The rate constants for intraparticle diffusion were 1.00 and 3.27 mg/g/min{sup 1/2} for 300 and 500 mg/l of dye, respectively.

  14. Kinetics of basic dye (methylene blue) biosorption by giant duckweed (Spirodela polyrrhiza)

    International Nuclear Information System (INIS)

    Sorbent dosage, pH and contact time were evaluated as factors affecting dye uptake by Spirodela polyrrhiza. - Wastewater containing pigments and/or dyes can cause serious water pollution problems in the form of reduced light penetration and photosynthesis, and the toxicity from heavy metals associated with pigments and/or dyes. Laboratory investigations, of the potential use of dried Spirodela polyrrhiza biomass as an adsorbent for the removal of the basic dye methylene blue from aqueous solution were conducted. A series of experiments were undertaken in an agitated batch adsorber to assess the effect of the system variables, i.e. sorbent dosage, pH, and contact time. The results showed that as the amount of the dried S. polyrrhiza increased, the percentage of dye sorption increased accordingly. At pH 2.0 the sorption of dye was not favorable, while the sorption at other pHs (3.0-11.0) was remarkable. There was no significant difference in the dye concentration remaining when the pH was increased from 3.0 to 11.0. The dye removal time was influenced by the initial dye concentration, and the process followed the first-order rate kinetics. The rate constants for intraparticle diffusion were 1.00 and 3.27 mg/g/min1/2 for 300 and 500 mg/l of dye, respectively

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

    OpenAIRE

    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:H...

  16. 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...

  17. Romaine lettuce latex deters feeding of banded cucumber beetle: a vehicle for deployment of biochemical defenses

    Science.gov (United States)

    Latex is widely found among plant species and is known to play a defensive role against certain herbivores. Two romaine lettuce cultivars, ‘Valmaine’ (resistant) and ‘Tall Guzmaine’ (susceptible) were selected to study the potential of latex as a defense mechanism against the banded cucumber beetle,...

  18. Population biology of Verticillium dahliae isolates from lettuce in the Sallinas Valley of Californis.

    Science.gov (United States)

    Verticillium dahliae is a soil borne fungus and the primary causal agent of Verticillium wilt, which affects many crops worldwide. Many crops grown in the Salinas Valley (SV) of California, including strawberry and lettuce (Lactuca sativa), are susceptible to V. dahliae and severe outbreaks are comm...

  19. 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 ...

  20. 7 CFR 319.56-24 - Lettuce and peppers from Israel.

    Science.gov (United States)

    2010-01-01

    ... ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN...houses covered with 50 mesh screens, double self-closing doors, and hard walks (no...The lettuce must be transported to the airport in a closed refrigerated truck for...