WorldWideScience

Sample records for water lettuce duckweed

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

    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.

    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

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

    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

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

    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

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

    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

  6. Comparative analysis of duckweed cultivation with sewage water and SH media for production of fuel ethanol.

    Changjiang Yu

    Full Text Available 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.

  7. DUCKWEED – A PERSPECTIVE VEGETABLE PLANT

    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

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

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

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

    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

  10. Transfer of Listeria innocua from contaminated compost and irrigation water to lettuce leaves.

    Oliveira, M; Usall, J; Viñas, I; Solsona, C; Abadias, M

    2011-05-01

    Many foodborne outbreaks of some pathogens such as Escherichia coli O157:H7, Salmonella or Listeria have been associated with the consumption of contaminated vegetables. Contaminated manure and polluted irrigation water are probable vehicles for the pathogens. The aim of this study was to determine the potential transfer of Listeria innocua from soil fertilized with contaminated compost or irrigated with contaminated water to the edible parts of lettuce grown on these soils together with its survival in lettuce and in soil under field conditions during two different seasons. Moreover, its survival on lettuce sprinkled with contaminated irrigation water was evaluated. L. innocua survived in soil samples for 9 weeks at high concentrations, 10(5) cfu gdw(-1) in fall and 10(3) cfu gdw(-1) in spring. Pathogen survived better in fall, indicating an important influence of temperature and humidity. L. innocua population in lettuce leaves was very high on lettuce leaves after sprinkling, but decreased to undetectable levels at field conditions. There was also transfer of L. innocua from soil contaminated with compost or irrigated with contaminated water to lettuce leaves, mainly to the outer ones. Survival profiles of L. innocua on lettuce and soil samples contaminated either by application of contaminated compost or surface irrigation water was similar. Our results indicated that contaminated compost and contaminated irrigation water can play an important role in the presence of foodborne pathogens on vegetables. PMID:21356469

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

    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/...

  12. Water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) in the Great Lakes: playing with fire?

    Adebayo, Abisola; Briski, Elizabeta; Kalaci, Odion; Hernandez, Marco; Ghabooli, Sara; Beric, Boris; Chan, Farrah; Zhan, Aibin; Fifield, Eric; Leadley, Todd; MacIsaac, Hugh

    2011-01-01

    The Laurentian Great Lakes have been successfully invaded by at least 182 nonindigenous species. Here we report on two new species, water hyacinth Eichhornia crassipes and water lettuce Pistia stratiotes, that were found at a number of locations in Lake St. Clair and Detroit River during autumn 2010. Both species are commonly sold in the water garden and aquarium trade in southern Ontario and elsewhere. While it is not clear whether these species are established or can establish in the Great ...

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

    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...

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

    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...

  15. Phytoremediation of wastewater toxicity using water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes).

    Victor, Kouamé Kouamé; Séka, Yapoga; Norbert, Kouadio Kouakou; Sanogo, Tidou Abiba; Celestin, Atsé Boua

    2016-10-01

    This paper elucidates the phytoremediation potential of water hyacinth and water lettuce on the reduction of wastewater toxicity. Acute toxicity tests were performed in an aquarium with a population of Sarotherodon melanotheron, contaminated by different concentrations of wastewaters before and after phytoremediation with Eichhornia crassipes and Pistia stratiotes. Lethal concentrations (LC50) of the fish's population obtained during 24 hours of exposures were determined. COD, BOD, ammonium, TKN and PO4(3-) concentrations in wastewaters were of 1850.29, 973.33, 38.34, 61.49 and 39.23 mg L(-1), respectively, for each plant. Phytoremediation reduced 58.87% of ammonium content, 50.04% of PO4(3-), 82.45% of COD and 84.91% of BOD. After 15 days of the experiment, metal contents in treated wastewaters decreased from 6.65 to 97.56% for water hyacinth and 3.51 to 93.51% for water lettuce tanks. Toxicity tests showed that the mortality of fish exposed increased with increase in concentration of pollutants in wastewaters and the time of exposure. Therefore, the highest value of LC50 was recorded for fish subjected to 3 hours of exposure (16.37%). The lowest rate was obtained after an exposure of 20 to 24 hours (5.85%). After phytoremediation, the effluents purified by Eichhornia crassipes can maintain the fish life beyond 24 hours of exposure. PMID:27159271

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

    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.

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

    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.

  18. Lettuce irrigated with contaminated water: Photosynthetic effects, antioxidative response and bioaccumulation of microcystin congeners.

    Bittencourt-Oliveira, Maria do Carmo; Cordeiro-Araújo, Micheline Kézia; Chia, Mathias Ahii; Arruda-Neto, João Dias de Toledo; Oliveira, Ênio Tiago de; Santos, Flávio Dos

    2016-06-01

    The use of microcystins (MCs) contaminated water to irrigate crop plants represents a human health risk due to their bioaccumulation potential. In addition, MCs cause oxidative stress and negatively influence photosynthetic activities in plants. The present study was aimed at investigating the effect of MCs on photosynthetic parameters and antioxidative response of lettuce. Furthermore, the bioaccumulation factor (BAF) of total MCs, MC-LR and MC-RR in the vegetable after irrigation with contaminated water was determined. Lettuce crops were irrigated for 15 days with water containing cyanobacterial crude extracts (Microcystis aeruginosa) with MC-LR (0.0, 0.5, 2.0, 5.0 and 10.0µgL(-1)), MC-RR (0.0, 0.15, 0.5, 1.5 and 3.0µgL(-1)) and total MCs (0.0, 0.65, 2.5, 6.5 and 13.0µgL(-1)). Increased net photosynthetic rate, stomatal conductance, leaf tissue transpiration and intercellular CO2 concentration were recorded in lettuce exposed to different MCs concentrations. Antioxidant response showed that glutathione S-transferase activity was down-regulated in the presence of MCs. On the other hand, superoxide dismutase, catalase and peroxidase activities were upregulated with increasing MCs concentrations. The bioaccumulation factor (BAF) of total MCs and MC-LR was highest at 6.50 and 5.00µgL(-1), respectively, while for MC-RR, the highest BAF was recorded at 1.50µgL(-1) concentration. The amount of total MCs, MC-LR and MC-RR bioacumulated in lettuce was highest at the highest exposure concentrations. However, at the lowest exposure concentration, there were no detectable levels of MC-LR, MC-RR and total MCs in lettuce. Thus, the bioaccumulation of MCs in lettuce varies according to the exposure concentration. In addition, the extent of physiological response of lettuce to the toxins relies on exposure concentrations. PMID:26896895

  19. Improving Water Use Efficiency of Lettuce (Lactuca sativa L.) Using Phosphorous Fertilizers

    AlKhader, Asad M F; Abu Rayyan, Azmi M

    2013-01-01

    A greenhouse pot experiment was conducted to evaluate the effect of phosphorous (P) fertilizers application to an alkaline calcareous soil on the water use efficiency (WUE) of lettuce cultivar “robinson” of iceberg type. Head fresh and dry weights, total water applied and WUE were affected significantly by the P fertilizer type and rate. P fertilizers addition induced a significant enhancement in the WUE and fresh and dry weights of the crop. A local phosphate rock (PR) applied directly was f...

  20. Phytoremediation of parboiled rice mill wastewater using water lettuce (Pistia stratiotes).

    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

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

    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.

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

    Hammady R. Soares

    2015-07-01

    Full Text Available 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 nutrient solution. In both experiments, the treatments were arranged in a randomized block design, with six treatments and four replicates. Shoot fresh matter, shoot dry matter and leaf area in Experiment I suffered reductions of 15.22, 12.67 and 15.6% per unit increase of EC, respectively. In Experiment II, reductions of 8.01, 6.90 and 8.14% were observed for the same variables, respectively. In Experiments I and II, linear decrease in water consumption due to the increase in salinity was observed, with reductions of 8.83 and 5.63% for each unit increase of electrical conductivity of water when the evapotranspiration was replenished using brackish and supply water, respectively.

  3. Genetic Control of Water and Nitrate Capture and Their Use Efficiency in Lettuce (Lactuca sativa L.).

    Kerbiriou, Pauline J; Maliepaard, Chris A; Stomph, Tjeerd Jan; Koper, Martin; Froissart, Dorothee; Roobeek, Ilja; Lammerts Van Bueren, Edith T; Struik, Paul C

    2016-01-01

    Robustness in lettuce, defined as the ability to produce stable yields across a wide range of environments, may be associated with below-ground traits such as water and nitrate capture. In lettuce, research on the role of root traits in resource acquisition has been rather limited. Exploring genetic variation for such traits and shoot performance in lettuce across environments can contribute to breeding for robustness. A population of 142 lettuce cultivars was evaluated during two seasons (spring and summer) in two different locations under organic cropping conditions, and water and nitrate capture below-ground and accumulation in the shoots were assessed at two sampling dates. Resource capture in each soil layer was measured using a volumetric method based on fresh and dry weight difference in the soil for soil moisture, and using an ion-specific electrode for nitrate. We used these results to carry out an association mapping study based on 1170 single nucleotide polymorphism markers. We demonstrated that our indirect, high-throughput phenotyping methodology was reliable and capable of quantifying genetic variation in resource capture. QTLs for below-ground traits were not detected at early sampling. Significant marker-trait associations were detected across trials for below-ground and shoot traits, in number and position varying with trial, highlighting the importance of the growing environment on the expression of the traits measured. The difficulty of identifying general patterns in the expression of the QTLs for below-ground traits across different environments calls for a more in-depth analysis of the physiological mechanisms at root level allowing sustained shoot growth. PMID:27064203

  4. Effect of Sea Lettuce (Ulva lactuca on Soil Water Holding Capacity

    Ömer Hulusi Dede

    2011-06-01

    Full Text Available In this study, the effect of sea lettuce (Ulva lactuca on soil water-holding capacity and the variation by over time were investigated. Sea lettuce (algae was collected from the Black Sea coast, rinsed with rain water and dried to constant weight. Dried algae were added to soil at rate of 0%, 2.5%, 5%, 10% and 20%. Mixtures were filling the pots and incubated for 0, 20, 40, 60 days at 25 ºC. At the end of the incubation, soil organic matter and water holding capacity were determined. Adding of algae to soil was increased the porosity and water holding capacity. The amount of the organic matter was decreased by the incubation progress. At the 20 and 40 days, micro-porosity was increased, air capacity decreased and water-holding capacity has not changed. At the 60th incubation days, reduction of organic matter content was slowed, air capacity was reached to normal values and water holding capacity was decreased. Total porosity was not changed. At the beginning (0th and the 60th incubation days, the distinctive dose was obtained at 5% for porosity and water holding capacity increases. Increased doses of the above have been limited. The optimum dose of 5% as determined by the addition of algae was increased soil water holding capacity by 48% on average.

  5. Capacity of Lemna gibba L. (duckweed) for uranium and arsenic phytoremediation in mine tailing waters.

    Mkandawire, Martin; Taubert, Barbara; Dudel, E Gert

    2004-01-01

    The potential of Lemna gibba L. to clean uranium and arsenic contamination from mine surface waters was investigated in wetlands of two former uranium mines in eastern Germany and in laboratory hydroponic culture. Water and plants were sampled and L gibba growth and yield were monitored in tailing ponds from the field study sites. Contaminant accumulation, growth and yield experiments were conducted in the laboratory using synthetic tailing water. Mean background concentrations of the surface waters were 186.0+/-81.2 microg l(-1) uranium and 47.0+/-21.3 microg l(-1) arsenic in Site one and 293.7+/-121.3 microg l(-1) uranium and 41.37+/-24.7 microg l(-1) arsenic in Site two. The initial concentration of both uranium and arsenic in the culture solutions was 100 microg l(-1). The plant samples were either not leached, leached with deionized H2O or ethylenediaminetetracetic (EDTA). The results revealed high bioaccumulation coefficients for both uranium and arsenic. Uranium and arsenic content of L gibba dry biomass of the field samples were as follows: nonleached samples > deionized H2O leached (insignificant ANOVA p = 0.05) > EDTA leached. The difference in both arsenic and uranium enrichment were significantly high between the nonleached and the other two lead samples tested at ANOVA p > 0.001. Estimated mean L gibba density in surface water was 85,344.8+/-1843.4 fronds m(-2) (approximately 1319.7 g m(-2)). The maximum specific growth rate was 0.47+/-0.2 d(-1), which exceeded reported specific growth rates for L gibba in the literature. Average yield was estimated at 20.2+/-6.7 g m(-2) d(-1), giving approximately 73.6+/-21.4 t ha(-1) y(-1) as the annual yield. The highest accumulations observed were 896.9+/-203.8 mg kg(-1) uranium and 1021.7+/-250.8 mg kg(-1) arsenic dry biomass for a 21-d test period in the laboratory steady-state experiments. The potential extractions from surface waters with L gibba L. were estimated to be 662.7 kg uranium ha(-1) yr(-1) and 751

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

    A. M. Snow

    2008-01-01

    Full Text Available Water hyacinth, water lettuce and parrot’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 parrot’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 parrot’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.

  7. Comparative transcriptome analysis to investigate the high starch accumulation of duckweed (Landoltia punctata) under nutrient starvation

    Tao, Xiang; Fang, Yang; Xiao, Yao; Jin, Yan-Ling; Ma, Xin-Rong; Zhao, Yun; He, Kai-ze; Zhao, Hai; Wang, Hai-Yan

    2013-01-01

    Background Duckweed can thrive on anthropogenic wastewater and produce tremendous biomass production. Due to its relatively high starch and low lignin percentage, duckweed is a good candidate for bioethanol fermentation. Previous studies have observed that water devoid of nutrients is good for starch accumulation, but its molecular mechanism remains unrevealed. Results This study globally analyzed the response to nutrient starvation in order to investigate the starch accumulation in duckweed ...

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

    Engin Gürtekin; Nusret Şekerdağ

    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...

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

    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.

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

    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

  11. Hormonal activity in detached lettuce leaves as affected by leaf water content.

    Aharoni, N; Blumenfeld, A; Richmond, A E

    1977-06-01

    The interrelationship between water deficiency and hormonal makeup in plants was investigated in detached leaves of romaine lettuce (Lactuca sativa L. cv. ;Hazera Yellow'). Water stress was imposed by desiccating the leaves for several hours in light or darkness at different air temperatures and relative humidity. In the course of desiccation, a rise in abscisic acid content and a decline in gibberellin and cytokinin activity were observed by gas-liquid chromatography, by both the barley endosperm bioassay and radioimmunoassay and by the soybean callus bioassay. Gibberellin activity began to decline in the stressed leaves before the rise in abscisic acid, the rate of this decline being positively correlated with the rate of increase in leaf water saturation deficit. Recovery from water stress was effected by immersing the leaf petioles in water while exposing the blades to high relative humidity. This resulted in a decrease in leaf water saturation deficit, a reduction in abscisic acid content, and an increase in gibberellin and cytokinin activity.Application of abscisic acid to the leaves caused partial stomatal closure in turgid lettuce leaves, whereas treatment with gibberellic acid and kinetin of such leaves had no effect on the stomatal aperture. In desiccating leaves, however, gibberellic acid and kinetin treatment considerably retarded stomatal closure, thus enhancing the increase in leaf water saturation deficit. These results suggest that the effect of desiccation in changing leaf hormonal make-up, i.e. a rapid increase in abscisic acid and a decrease in both cytokinin and gibberellin activity, is related to a mechanism designed to curtail water loss under conditions inducing water deficiency. PMID:16660015

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

    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.

  13. Improving Water Use Efficiency of Lettuce (Lactuca sativa L.) Using Phosphorous Fertilizers.

    Alkhader, Asad M F; Abu Rayyan, Azmi M

    2013-01-01

    A greenhouse pot experiment was conducted to evaluate the effect of phosphorous (P) fertilizers application to an alkaline calcareous soil on the water use efficiency (WUE) of lettuce cultivar "robinson" of iceberg type. Head fresh and dry weights, total water applied and WUE were affected significantly by the P fertilizer type and rate. P fertilizers addition induced a significant enhancement in the WUE and fresh and dry weights of the crop. A local phosphate rock (PR) applied directly was found to be inferior to the other types of P fertilizers (Mono ammonium phosphate (MAP), Single superphosphate (SSP), and Di ammonium phosphate ((DAP)). MAP fertilizer at 375 and 500 kg P2O5/ha application rates recorded the highest significant values of head fresh weight and WUE, respectively. PMID:24255857

  14. Duck-Weed as an ecotoxicological biotest

    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

  15. Pilot scale application of ozonated water wash - effect on microbiological and sensory quality parameters of processed iceberg lettuce during self-life

    Särkkä-Tirkkonen, Marjo; Leskinen, Marita; Ölmez, Hulya

    2008-01-01

    The aim of the study was to assess the effect of ozonated water wash on the microbiological and sensory quality parameters of minimally processed iceberg lettuce in pilot scale in comparison to aqueous chlorine wash. Alternative solutions for chlorine are needed, since its use is prohibited in organic food processing. Iceberg lettuce samples were washed with three different ozone solutions and the water wash and the 100 ppm chlorine wash were used as control. Ozone generator based on corona d...

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

    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

  17. Growing duckweed for biofuel production: a review.

    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

  18. Enteric pathogen survival varies substantially in irrigation water from Belgian lettuce producers.

    Van Der Linden, Inge; Cottyn, Bart; Uyttendaele, Mieke; Berkvens, Nick; Vlaemynck, Geertrui; Heyndrickx, Marc; Maes, Martine

    2014-01-01

    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

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

    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

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

    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.

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

    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

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

    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...

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

    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

  4. Nutrients valorisation via Duckweed-based wastewater treatment and aquaculture

    Mohamed El-Shafai, S.A.A.

    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 tr

  5. Adjuvants affect duckweed (Lemna minor) control with pelargonic acid

    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 ...

  6. Presence and survival of Escherichia coli O157:H7 on lettuce leaves and in soil treated with contaminated compost and irrigation water.

    Oliveira, M; Viñas, I; Usall, J; Anguera, M; Abadias, M

    2012-05-15

    Escherichia coli O157:H7 outbreaks associated with produce consumption have brought attention to contaminated compost manure, and polluted irrigation water as potential sources of pathogens for the contamination of these crops. The aim of this study was to determine the potential transfer of E. coli O157:H7 from soil fertilized with contaminated compost or irrigated with contaminated water to edible parts of lettuce together with its persistence in soil under field conditions in two different seasons (fall and spring). Moreover, its survival on lettuce sprinkled with contaminated irrigation water was evaluated, as well as the prevalence of aerobic mesophilic, Enterobacteriaceae and Pseudomonadaceae in control lettuce samples. Four treatments, contaminated compost, surface and sprinkle irrigation with contaminated water and uninoculated pots, were used in this work. Contaminated compost was applied to soil in the pots before lettuce was transplanted and contaminated irrigation water was applied twice and three times on the plants after the seedlings were transplanted, for sprinkle and surface irrigation, respectively. E. coli O157:H7 survived in soil samples for 9 weeks at levels, 4.50 log cfu gdw(-1) (dw, dry weight) in fall and 1.50 log cfu gdw(-1) in spring. The pathogen survives better in fall, indicating an important influence of environmental factors. E. coli O157:H7 population in lettuce leaves after sprinkle irrigation was very high (between 10(3) and 10(6) cfu g(-1)), but decreased to undetectable levels at field conditions. There was also transfer of E. coli O157:H7 from soil contaminated with compost or irrigated with contaminated water to lettuce leaves, mainly to the outer ones. The mean counts for aerobic mesophilic, Enterobacteriaceae and Pseudomonadaceae populations were also influenced by environmental conditions; higher levels were observed under fall conditions than in spring conditions. Contamination of lettuce plants in the field can occur

  7. Efficacy of Slightly Acidic Electrolyzed Water and UV-Ozonated Water Combination for Inactivating Escherichia Coli O157:H7 on Romaine and Iceberg Lettuce during Spray Washing Process.

    Pang, Yu-Hsin; Hung, Yen-Con

    2016-07-01

    Spray washing is a common sanitizing method for the fresh produce industry. The purpose of this research was to investigate the antimicrobial effect of spraying slightly acidic electrolyzed water (SAEW) and a combination of ozonated water with ultraviolet (UV) in reducing Escherichia coli O157:H7 on romaine and iceberg lettuces. Both romaine and iceberg lettuces were spot inoculated with 100 μL of a 3 strain mixture of E. coli O157:H7 to achieve an inoculum of 6 log CFU/g on lettuce. A strong antimicrobial effect was observed for the UV-ozonated water combination, which reduced the population of E. coli by 5 log CFU/g of E. coli O157:H7 on both lettuces. SAEW achieved about 5 log CFU/g reductions in the bacterial counts on romaine lettuce. However, less than 2.5 log CFU/g in the population of E. coli O157:H7 was reduced on iceberg lettuce. The difference may be due to bacteria aggregation near and within stomata for iceberg lettuce but not for romaine lettuce. The UV light treatment may stimulate the opening of the stomata for the UV-ozonated water treatment and hence achieve better bacterial inactivation than the SAEW treatment for iceberg lettuce. Our results demonstrated that the combined treatment of SAEW and UV-ozonated water in the spray washing process could more effectively reduce E. coli O157:H7 on lettuce, which in turn may help reduce incidences of E. coli O157:H7 outbreaks. PMID:27305593

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

    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.

  9. Bioeconomic Modeling of the Invasive Aquatic Plants Hydrilla verticillata (hydrilla), Eichhornia crassipes (water hyacinth), and Pistia stratiotes (water lettuce) and their impacts on angler effort on Florida lakes

    Adams, Damian C.; Lee, Donna J.

    2005-01-01

    The invasive aquatic plants Hydrilla verticillata (hydrilla), Eichhornia crassipes (water hyacinth), and Pistia stratiotes (water lettuce) have the potential to negatively impact recreational use of Florida lakes if consistent, adequate control expenditures are not made. In the mid-1990's, Florida significantly reduced its spending on invasive aquatic plant control measures, which resulted in a significant increase in needed control expenditures in subsequent years. This paper attempts to for...

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

    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

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

    Mkandawire, Martin; Dudel, E Gert

    2005-01-01

    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-Mechelgrun were analysed for arsenic. Laboratory cultures in nutrient solutions modified with six arsenic and three PO(4)(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(4)(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

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

    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

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

    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.

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

    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

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

    Effendi, Hefni; Wahyuningsih, Sri; Wardiatno, Yusli

    2016-05-01

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

  16. Evaluation of lettuce genotypes for salinity tolerance

    Lettuce is one of the most commonly used salad vegetables and considered to be a relatively salt sensitive crop. Salinity is a major constraint to crop production in all important lettuce districts of the U.S., and the water quality problem is exacerbated by the climate change. In order to identify ...

  17. Response of duckweed to various concentrations of selenite.

    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

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

    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, β-blockers, phenolic estrogens, anticonvulsants, stimulants, polycyclic musks, biocides) at different concentrations (0-40μgL(-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

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

    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

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

    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

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

    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.

  2. The Removal of Cyanobacterial Hepatotoxin [Dha(7)] Microcystin-LR via Bioaccumulation in Water Lettuce (Pistia stratiotes L.).

    Somdee, Theerasak; Thathong, Benjamad; Somdee, Anchana

    2016-03-01

    The removal of [Dha(7)] microcystin-LR through bioaccumulation in six aquatic plants was investigated. The aquatic plant water lettuce (Pistia stratiotes L.) exhibited the highest removal, with 13 % of the toxin remaining after a 7-day exposure period. Removal by P. stratiotes (with 0.5 and 1.0 mg/L of the toxin) was faster and greater in static systems than in continuous flow systems. In the static experiment, P. stratiotes roots accumulated [Dha(7)] microcystin-LR up to a concentration of 0.0088 ng/mg wet wt. plant material, whereas in the continuous flow system, the plant root tissue accumulated the toxin up to a concentration of 0.0041 ng/mg wet wt. plant material. Exposure to the toxin at concentrations of 0.5 and 1.0 mg/L induced changes in the development of P. stratiotes, including short, thin and rotted roots with decreased leaf counts after 3 days of exposure. PMID:26687499

  3. Pathogenic and commensal Escherichia coli from irrigation water show potential in transmission of extended spectrum and AmpC β-lactamases determinants to isolates from lettuce

    Njage, Patrick M K; Buys, Elna M

    2014-01-01

    There are few studies on the presence of extended-spectrum β-lactamases and AmpC β-lactamases (ESBL/AmpC) in bacteria that contaminate vegetables. The role of the production environment in ESBL/AmpC gene transmission is poorly understood. The occurrence of ESBL/AmpC in E scherichia coli (n = 46) from lettuce and irrigation water and the role of irrigation water in the transmission of resistant E . coli were studied. The presence of ESBL/AmpC, genetic similarity and phylogeny were typed using ...

  4. Lettuce contact allergy.

    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

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

    Inge Van der Linden; Bart Cottyn; Mieke Uyttendaele; Nick Berkvens; Geertrui Vlaemynck; Marc Heyndrickx; Martine Maes

    2014-01-01

    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 t...

  6. Lettuce contact allergy

    Paulsen, Evy; Andersen, Klaus E

    2016-01-01

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

  7. Mutations in Lettuce Improvement

    2012-01-01

    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...

  8. Water deficit improved the capacity of arbuscular mycorrhizal fungi (AMF) for inducing the accumulation of antioxidant compounds in lettuce leaves.

    M. Baslam; Goicoechea, N.

    2012-01-01

    Lettuce, a major food crop within the European Union and the most used for the so-called 'Fourth Range' of vegetables, can associate with arbuscular mycorrhizal fungi (AMF). Mycorrhizal symbiosis can stimulate the synthesis of secondary metabolites, which may increase plant tolerance to stresses and enhance the accumulation of antioxidant compounds potentially beneficial to human health. Our objectives were to assess (1) if the application of a commercial formulation of AMF benefited growth o...

  9. Mutations in lettuce improvement.

    Mou, Beiquan

    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 studies including identification and cloning of disease-resistance genes. Mutagenesis combined with genomic technology may provide powerful tools for the discovery of novel gene alleles. In addition to radiation and chemical mutagens, unconventional approaches such as tissue or protoplast culture, transposable elements, and space flights have been utilized to generate mutants in lettuce. Since mutation breeding is considered nontransgenic, it is more acceptable to consumers and will be explored more in the future for lettuce improvement. PMID:22287955

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

    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.

  11. Nutrient removal from swine lagoon effluent by duckweed

    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%.

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

    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

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

    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

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

    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

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

    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

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

    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)

  17. Arsenic uptake, accumulation and phytofiltration by duckweed (Spirodela polyrhiza L.)

    Xin Zhang; Ying Hu; Yunxia Liu; Baodong Chen

    2011-01-01

    This study investigates arsenic (As) accumulation and tolerance of duckweed Spirodela polyrhiza L. and its potential for As phytofiltration. S. polyrhiza was able to survive in high concentration of As(V) solution. The EC50 values (± SE) based on the external As(V) were (181.66 ± 20.12) μmol/L. It accumulated (999 ± 95) mg As/kg dw when exposed in 320 μmol/L As(V) solution for one week, and was able to take up appropriately 400 mg As/kg dw in tissues without a significant biomass loss. The EC50 values (the effective concentration of As(V) in the nutrient solution that caused a 50% inhibition on biomass production) was (866 ± 68) mg/kg dw for the tissues, indicating that S. polyrhiza had a high capability of As accumulation and tolerance. The uptake kinetic parameters Vmax was (55.33 ± 2.24) nmol/(g dw.min) and Kn was (0.144 ± 0.011) mmol/L. Within 72 hr, S. polyrhiza decreased As concentration in the solution from 190 to 113 ng/mL with a removal rate of 41%. The study suggested that this floating aquatic plant has some potential for As phytofiltration in contaminated water bodies or paddy soils.

  18. Ecophysiological tolerance of duckweeds exposed to copper

    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

  19. Ecophysiological tolerance of duckweeds exposed to copper

    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 μM) to the highest (100 μM), 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 μM) whereas for Lm(EC1) and SP a significant decrease in chl a and carotenoids was observed only at 50 and 100 μM-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 μM-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 μM-Cu) whereas, for Lm(EC2), this effect started to be significant after an exposure to 50 μM-Cu. Superoxide dismutase (SOD) activity

  20. USDA lettuce breeding and genetics

    The lettuce industry of California requires continued development of improved, adapted cultivars to meet new disease and insect problems, changes in the market, and changes in growing procedures. The USDA lettuce breeding and genetics project aims to incorporate valuable traits into crisphead, mixed...

  1. Growth and photosynthesis of lettuce

    Holsteijn, van H.M.C.

    1981-01-01

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

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

    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...

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

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

    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

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

    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

  6. SURVEY OF BIOLOGICAL HAZARDS IN THE LETTUCE USED IN COMMERCIAL SNACKS (SANDWICHES FROM CURITIBA, PR, BRAZIL

    Assuan Djamila Ibrahim MOGHARBEL

    2009-06-01

    Full Text Available

    Over the last decades, lettuce has been associated to several foodborne outbreaks. The present study surveyed the microbiological and parasitological contamination of green leaf lettuce used in sandwiches sold in snack bars in Curitiba, Paraná, Brazil. Lettuce was collected before and after commercial washing. Such procedure was made by holding and rotating the whole lettuce or separated leaves under the faucet of a sink with cold water for 10-30s. Three samples of 25g of lettuce leaves from each snack bar were assessed for mesophilic aerobic bacteria, molds and yeasts, Escherichia coli, incidence (% of general parasites, Salmonella spp, Staphylococcus aureus. The obtained mean counts, expressed as Colony Forming Units per gram of lettuce, were respectively: 5.9 x 106; 6.4 x 103; 2.1 x 102; 73%, for non-washed samples; and 7.3 x 104; 5.9 x 103; 1.0 x 102; 18%, for washed samples. The water washing, as it has been performed in the food establishments investigated, showed to be ineffi cient for sanitizing lettuce. Though Salmonella and Staphylococcus aureus were not found, the results refl ect unsanitary production practices and show that the assessed lettuce has been a source of biological hazard.

  7. Ethylene and lettuce seed germination

    Nascimento Warley Marcos

    2003-01-01

    Ethylene can stimulate seed germination and overcome dormancy in many species. For instance, the inhibitory effect of high temperature on lettuce seed germination can be overcome by exogenous ethylene. Involvement of ethylene in seed germination is a widely accepted fact, but the mechanistic details are poorly understood. A critical factor in ethylene studies is the response of seed germination properties to various ethylene inhibitors. Lettuce seed has been used as a model to study the role ...

  8. Growth and photosynthesis of lettuce

    Holsteijn, van, H.M.C.

    1981-01-01

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

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

    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.

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

    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

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

    Keraita, Bernard; Konradsen, Flemming; Drechsel, Pay;

    2007-01-01

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

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

    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...

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

    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 ) stabilisa

  14. 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

    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

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

    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%, α-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

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

    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.

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

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

    2015-12-01

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

  18. Efficacy of Steamer Jet-Injection as Alternative to Chlorine in Fresh-Cut Lettuce

    Martin-Diana, Ana Belen; Rico, Daniel; Barry-Ryan, Catherine; Frias, Jesus Maria; Henehan, Gary; Barat, J.

    2007-01-01

    Short-time steam processing was used as an alternative to chlorine (100 mg L−1) in sanitising fresh-cut lettuce. Quality (pH, water content, colour, potential browning, browning-related enzymes and texture), safety (mesophilic counts) and antioxidant markers (ascorbic and carotenoids) were monitored in lettuce stored for 10 days at 4 °C. The steam treatment produced a shocking effect on lettuce metabolism, showing a significant (p < 0.05) reduction in respiration (from day 3 to 7) and a parti...

  19. Usage of Some Duckweeds in Nutrient Removal

    Topal, Murat; KARAGÖZOĞLU, Bünyamin; ÖBEK, Erdal; TOPAL, E. Işıl Arslan

    2011-01-01

    In recent years, studies about the protection of wetlands have growing importance in our country. Therefore, detection of all pollutant sources which enter to surface waters and/or lakes is needed. Particularly wastewaters are discharged to surface waters and/or lakes in most regions. This causes increase of C, N, P which present in wastewater in water environment. As a result of this, the increase of nutrient causes pollution a...

  20. Duckweed Uptake of Phosphorus and Five Pharmaceuticals: Microcosm and Wastewater Lagoon Studies

    Farrell, Jonathan Bay

    2012-01-01

    Duckweed species L. turionifera and W. borealis grow on Wellsville Municipal Sewage Lagoons in northern Utah and, when harvested, contribute to the removal of phosphorus and pharmaceuticals from wastewater. Microcosm studies showed that duckweed contains an average of 1% phosphorus (dry weight) and removes 113 mg-P/m2day under 200 μmol/m2sec light. Duckweed in laboratory experiments reduced influent phosphorus ranging from 3.88 to 5.2 mg-TP/L to effluent concentrations of 0.88 mg-P/L in 3 day...

  1. Tannin extracts on quality of fresh cut crisp leaf lettuce

    Tâmmila Venzke Klug

    2016-01-01

    Full Text Available ABSTRACT: In the present study, tannin extracts (rinsed or not were compared to the use of sodium hypochlorite and tap water on fresh cut crisp leaf lettuce stored under modified atmosphere packaging. Effects of these sanitizers on total color difference and microbial levels of the product after sanitization and storage for 9 days at 3°C were evaluated. Performance of rinsed SM(r tannin extract was comparable to the results of chlorine solution for all the analyzed parameters and; furthermore, that extract presented a high reduction in the initial bacterial count of minimally processed lettuce. However, storage of tannin extracts, did not impart better outcomes than the use of tap water. Therefore, the tannin extract storage SM(r could be used in washing water to reduce the initial microbiological load, avoiding cross contamination in vegetables minimally processed.

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

    GÜLÇİN, İlhami; *,; KİREÇCİ, Ekrem; AKKEMİK, Ebru; TOPAL, Fevzi; HİSAR, 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-...

  3. Greenhouse lettuce production with and without nutrient solution recycling

    Esaú del C. Moreno-Pérez; Felipe Sánchez-Del Castillo; Jorge Gutiérrez-Tlaque; Lucila González-Molina; Joel Pineda-Pineda

    2015-01-01

    Hydroponic systems with nutrient solution recycling provide more efficient water and fertilizer use, but over time it becomes difficult to sustain the nutritional balance and control diseases that attack plant roots, which eventually results in lower yield compared to systems where nutrient solution is not recycled. The aim of this study was to evaluate the yield and earliness of butter lettuce (Cortesana M1 variety) grown with different hydroponic systems and their efficiency in terms of wat...

  4. Use of Propolis in the Sanitization of Lettuce

    Xesús Feás; Lazaro Pacheco; Antonio Iglesias; Estevinho, Leticia M.

    2014-01-01

    The present study aimed to determine the effectiveness of propolis in reducing the microbial load in ready-to-eat (RTE) and fresh whole head (FWH) lettuces (Lactuca sativa L.) type Batavia. Two sanitizing solutions were employed: sodium hypochlorite (SH) and propolis (PS), during 15 and 30 min. Tap water (TW) was used as a control. Regarding the mean reduction on aerobic mesophiles, psychrotrophic and fecal coliforms, the SH and PS treatments showed the same pattern of variation. In all case...

  5. Sustainable lettuce: Adaptability to uncertain production conditions

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

  6. Zooming in on the lettuce genome

    Koopman, W.J.M.

    2002-01-01

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

  7. Genetics of resistance against lettuce downy mildew

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

  8. 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

    Dalva Paulus

    2012-03-01

    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.

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

    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.

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

    Mroczek, E; Konieczny, P; Kleiber, T; Waśkiewicz, 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

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

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

    2007-01-01

    OBJECTIVE: To assess the effectiveness of simple irrigation methods such as drip irrigation kits, furrow irrigation and use of watering cans in reducing contamination of lettuce irrigated with polluted water in urban farming in Ghana. METHODS: Trials on drip kits, furrow irrigation and watering c...

  12. Possible Internalization of an Enterovirus in Hydroponically Grown Lettuce

    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.

  13. Transfer of Escherichia coli O157:H7 to iceberg lettuce via simulated field coring.

    Taormina, Peter J; Beuchat, Larry R; Erickson, Marilyn C; Ma, Li; Zhang, Guodong; Doyle, Michael P

    2009-03-01

    The field-core (cut and core) harvesting technique used for iceberg lettuce was evaluated as a potential means of cross-contamination with Escherichia coli O157:H7. Chlorinated water treatment was evaluated for its efficacy in removing or inactivating the pathogen on the blade portion of the field coring device and on cored lettuce. Field coring devices inoculated by immersing blades in soil containing E. coli O157:H7 at 3.74 or 6.57 log CFU/g contained 3.13 and 4.97 log CFU per blade, respectively. Treatment of inoculated field coring device blades by immersing in chlorinated water (200 microg/ml total chlorine) for 10 s resulted in a reduction of 1.56 log CFU per blade, which was 1.42 log CFU per blade greater than that achieved using water, but insufficient to eliminate the pathogen on blades. Field coring devices inoculated by contacting soil containing E. coli O157:H7 at 2.72 and 1.67 log CFU/g, then repeatedly used to cut and core 10 lettuce heads, transferred the pathogen to 10 and 5 consecutively processed heads, respectively. Lettuce cores remained positive for the pathogen after spraying with 100 microg/ml free chlorine for 120 s at 2.81 kg/cm2 (40 lb/in2), regardless of the inoculum level. The number of E. coli O157:H7 recovered from inoculated lettuce cores treated for 10 s with chlorine was significantly (P < or = 0.05) different from the number recovered from tissues treated with water. Dipping contaminated field coring devices in chlorinated water may not be effective in killing the pathogen and controlling cross-contamination from head to head. Spraying contaminated lettuce with chlorinated or untreated water reduces but does not eliminate E. coli O157:H7. PMID:19343932

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

    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.

  15. Modelling algae-duckweed interaction under chemical pressure within a laboratory microcosm.

    Lamonica, Dominique; Clément, Bernard; Charles, Sandrine; Lopes, Christelle

    2016-06-01

    Contaminant effects on species are generally assessed with single-species bioassays. As a consequence, interactions between species that occur in ecosystems are not taken into account. To investigate the effects of contaminants on interacting species dynamics, our study describes the functioning of a 2-L laboratory microcosm with two species, the duckweed Lemna minor and the microalgae Pseudokirchneriella subcapitata, exposed to cadmium contamination. We modelled the dynamics of both species and their interactions using a mechanistic model based on coupled ordinary differential equations. The main processes occurring in this two-species microcosm were thus formalised, including growth and settling of algae, growth of duckweeds, interspecific competition between the two species and cadmium effects. We estimated model parameters by Bayesian inference, using simultaneously all the data issued from multiple laboratory experiments specifically conducted for this study. Cadmium concentrations ranged between 0 and 50 μg·L(-1). For all parameters of our model, we obtained biologically realistic values and reasonable uncertainties. Only duckweed dynamics was affected by interspecific competition, while algal dynamics was not impaired. Growth rate of both species decreased with cadmium concentration, as well as competition intensity showing that the interspecific competition pressure on duckweed decreased with cadmium concentration. This innovative combination of mechanistic modelling and model-guided experiments was successful to understand the algae-duckweed microcosm functioning without and with contaminant. This approach appears promising to include interactions between species when studying contaminant effects on ecosystem functioning. PMID:26922150

  16. Effects of High Ammonium Concentration on Growth and Nutrient Uptake of Lettuce Plants with Solution Culture

    2005-01-01

    A nutrition solution experiment was conducted over two months to investigate the response of vegetable crops to high concentrations of ammonium, using lettuce (Lactuca sativa L. cv. Angustana Irish) as a test crop. Ammonium concentrations were designed in 5 levels, ranging from 12 mmol N L-1 to 22 mmol N L-1 and local tap water was used as water source. At the first culture stage (0-9 days), lettuce plants maintained normal growth while the lettuce roots were increasingly impaired. During the subsequent three stages the root structure was greatly damaged, and roots became brown or black through continuous supply of high concentration of ammonium. However, there was no obvious reduction of the aboveground biomass of the plants in the high ammonium treatments compared to those supplied with nitrate alone. In contrast to results obtained in another experiment from us with distilled water, the detrimental effect of high ammonium concentration on lettuce growth was greatly alleviated. Based on the results, it was postulated that the small amount of nitrate and the higher amount of bicarbonate existed in the tap water might mitigate the adverse effects of high ammonium N. The higher bicarbonate content in water and soil has usually been regarded as a major constraint factor limiting plant growth in calcareous soil areas. However, the reaction of bicarbonate to ammonium might produce positively interactive effect on reduction of both damages. The lettuce plants grown in ammonium solutions took up less P, K, Fe, Mn and Cu and more Ca than those grown in the nitrate nutrient solution. In conclusion, the results indicated that the N form imposed an obvious influence on absorption of cations and anions. Supplying ammonium-N stimulated transport of Ca, Mg and Mn to shoots of lettuce.

  17. Shoot growth, root growth and resource capture under limiting water and N supply for two cultivars of lettuce (Lactuca sativa L.)

    Kerbiriou, P.J.; Stomph, T.J.; Putten, van der P.E.L.; Lammerts Van Bueren, E.; Struik, P.C.

    2013-01-01

    Background and aims - To improve vegetable crops adapted to low input and variable resource availability, better understanding is needed of root system functioning, including nitrogen and water capture. Methods - This study quantified shoot and root development and patterns of water and nitrate capt

  18. Succinic acid production from duckweed (Landoltia punctata) hydrolysate by batch fermentation of Actinobacillus succinogenes GXAS137.

    Shen, Naikun; Wang, Qingyan; Zhu, Jing; Qin, Yan; Liao, Siming; Li, Yi; Zhu, Qixia; Jin, Yanling; Du, Liqin; Huang, Ribo

    2016-07-01

    Duckweed is potentially an ideal succinic acid (SA) feedstock due to its high proportion of starch and low lignin content. Pretreatment methods, substrate content and nitrogen source were investigated to enhance the bioconversion of duckweed to SA and to reduce the costs of production. Results showed that acid hydrolysis was an effective pretreatment method because of its high SA yield. The optimum substrate concentration was 140g/L. The optimum substrate concentration was 140g/L. Corn steep liquor powder could be considered a feasible and inexpensive alternative to yeast extract as a nitrogen source. Approximately 57.85g/L of SA was produced when batch fermentation was conducted in a 1.3L stirred bioreactor. Therefore, inexpensive duckweed can be a promising feedstock for the economical and efficient production of SA through fermentation by Actinobacillus succinogenes GXAS137. PMID:27023386

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

    Dalva Paulus

    2010-03-01

    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.

  20. Duckweed (Lemna minor as a model plant system for the study of human microbial pathogenesis.

    Yong Zhang

    Full Text Available BACKGROUND: Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions. METHODOLOGY/PRINCIPAL FINDINGS: We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals.

  1. The role of duckweed in bio-liquid fuel production and environmental protection

    Zhao Hai

    2014-01-01

    With the world economic development,population growth and improvement of people’s living stan dard,the energy shortage has become the core issue of restricting the development of the world economy. China faces serious energy crisis and environmental problems,so the development of biofuels in China is vital. This paper introduces the advantages of duckweed for energy production,summarizes the research results of Cheng du Institute of Biology on duckweed,and provides the direction of its further study.

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

    This study compared the efficacy of chlorine (20 – 200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20 – 200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20 – 200 ppm chlorite ion concentration, TriNova) washes in reducing population...

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

    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

  4. Clonal expansion of Verticillium dahliae in lettuce.

    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 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

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

    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.

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

    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 μmol/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.

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

    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.

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

    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.

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

    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

  10. Dynamics of lettuce drop incidence and Sclerotinia minor inoculum under varied crop rotations

    Hao, J J; Subbarao, K.V.

    2006-01-01

    Field experiments were conducted to determine the population dynamics of Sclerotinia minor and incidence of lettuce drop at two sites during 1995 to 1998. Rotation treatments at the Spence site, which had a low density of inoculum ( 7 sclerotia per 100 cm(3) of soil) that was distributed uniformly, included: continuous lettuce (LLLL), alternate crops of broccoli and lettuce (BLBL), continuous broccoli or lettuce (BBLL), and fallow-lettuce-fallow-lettuce (FLFL). Under continuous lettuce croppi...

  11. A fast molecular nondestructive protocol for evaluating aerobic bacterial load on fresh-cut lettuce.

    Gómez, P; Pagnon, M; Egea-Cortines, M; Artés, F; Weiss, J

    2010-10-01

    Elaboration of minimally processed or fresh-cut vegetables requires a quick and reliable method for detection of bacterial contamination over the recommended limits. PCR-based methods fulfil these requirements, but amplification from DNA preparations of the food product is often hampered due to inhibiting substances. The purpose of this study was to develop a fast quantitative PCR (qPCR)-based method for aerobic bacterial enumeration in fresh-cut lettuce, using as reference the centrifugation water (CW) that comes up during processing instead of the food matrix itself. Comparisons between bacterial numbers on lettuce leaves before processing and bacterial numbers in the CW both for naturally occurring bacterial populations and for artificially inoculated lettuce were performed. On an average, 35% of the natural bacterial population and 64% of inoculated bacteria were recovered in the CW. Bacterial number in CW was proportional to initial lettuce contamination suggesting that measures on CW allow a narrow estimation of lettuce contamination. In qPCR, a 23S rDNA region was amplified from bacterial DNA present in the CW, followed by melting peak analyses and quantification. Enumeration of cell number by qPCR did not differ significantly from plate assay and might therefore replace it. The proposed protocol, which includes sample taking, DNA extraction and qPCR from the CW can be performed within less than 5 h. The resulting quantification might be used as a proxy of initial lettuce contamination, allowing direct intervention measures before fresh-cut commodity is shipped from the factory. PMID:21339159

  12. Impact of mulches and growing season on indicator bacteria survival during lettuce cultivation.

    Xu, Aixia; Buchanan, Robert L; Micallef, Shirley A

    2016-05-01

    In fresh produce production, the use of mulches as ground cover to retain moisture and control weeds is a common agricultural practice, but the influence that various mulches have on enteric pathogen survival and dispersal is unknown. The goal of this study was to assess the impact of different mulching methods on the survival of soil and epiphytic fecal indicator bacteria on organically grown lettuce during different growing seasons. Organically managed lettuce, cultivated with various ground covers - polyethylene plastic, corn-based biodegradable plastic, paper and straw mulch - and bare ground as a no-mulch control, was overhead inoculated with manure-contaminated water containing known levels of generic Escherichia coli and Enterococcus spp. Leaves and soil samples were collected at intervals over a two week period on days 0, 1, 3, 5, 7, 10 and 14, and quantitatively assessed for E. coli, fecal coliforms and Enterococcus spp. Data were analyzed using mixed models with repeated measures and an exponential decline with asymptote survival model. Indicator bacterial concentrations in the lettuce phyllosphere decreased over time under all treatments, with more rapid E. coli declines in the fall than in the spring (pmodel gave very good fits for the progression of E. coli concentrations in the phyllosphere over time (R(2)=0.88±0.12). In the spring season, decline rates of E. coli counts were faster (2013 p=0.18; 2014 psoil compared to lettuce phyllosphere, and mulch type was a factor for fecal coliform levels (pstudy demonstrates that mulches used in lettuce production may impact the fate of enteric bacteria in soil or on lettuce, most likely in relation to soil moisture retention, and other weather-related factors, such as temperature and rainfall. The data suggest that the time between exposure to a source of enteric bacteria and harvesting of the crop is season dependent, which has implications for determining best harvest times. PMID:26938806

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

    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

  14. Sources of Verticillium dahliae affecting lettuce.

    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

  15. Folates in lettuce: a pilot study

    Johansson, Madelene; Jägerstad, Margaretha; Frølich, Wenche

    2007-01-01

    Background Leafy vegetables are good sources of folates and food shops nowadays offer an increasing number of lettuce varieties. Objective To obtain data on the folate content and forms in common lettuce varieties and spinach sold in the Nordic countries, and to investigate effects of different storage conditions and preparations in the consumer's home or at lunchtime restaurants. Design Folate was analysed in eight different lettuce varieties and spinach using a validated high-performance liquid chromatographic method and the detected forms of folates were confirmed by a mass spectrometric detector [liquid chromatography–mass spectrometry (LC-MS)] following heat extraction, deconjugation with rat serum and purification by solid-phase extraction. Results Folate content, expressed in folic acid equivalents, in the lettuce samples varied six-fold, from 30 to 198 µg 100 g−1 on a fresh weight basis. The folate content was decreased by 14% after storage at 4°C for 8 days and by 2–40% after storage at 22°C for 2–4 h, depending on whether samples were stored as whole leaves, or small torn or cut pieces. LC-MS confirmed the identity of the folate forms: H4folate, 5-CH3-H4folate, 5-HCO-H4folate and 10-HCO-H4folate. Conclusion The considerable variation in folate content between varieties of lettuce in this pilot study, with one variety reaching the level found in spinach, indicates the potential to increase folate intake considerably by choosing folate-rich varieties of lettuce and storing at low temperatures.

  16. Stability of bovine coronavirus on lettuce surfaces under household refrigeration conditions

    Mullis, Lisa; Saif, Linda J.; Zhang, Yongbin; Zhang, Xuming; Azevedo, Marli S.P.

    2016-01-01

    Fecal suspensions with an aerosol route of transmission were responsible for a cluster of severe acute respiratory syndrome (SARS) cases in 2003 in Hong Kong. Based on that event, the World Health Organization recommended that research be implemented to define modes of transmission of SARS coronavirus through sewage, feces, food and water. Environmental studies have shown that animal coronaviruses remain infectious in water and sewage for up to a year depending on the temperature and humidity. In this study, we examined coronavirus stability on lettuce surfaces. A cell culture adapted bovine coronavirus, diluted in growth media or in bovine fecal suspensions to simulate fecal contamination was used to spike romaine lettuce. qRT-PCR detected viral RNA copy number ranging from 6.6 × 104 to 1.7 × 106 throughout the experimental period of 30 days. Whereas infectious viruses were detected for at least 14 days, the amount of infectious virus varied, depending upon the diluent used for spiking the lettuce. UV and confocal microscopic observation indicated attachment of residual labeled virions to the lettuce surface after the elution procedure, suggesting that rates of inactivation or detection of the virus may be underestimated. Thus, it is possible that contaminated vegetables may be potential vehicles for coronavirus zoonotic transmission to humans. PMID:22265299

  17. Characterisation of lettuce virus X, a new potexvirus infecting lettuce in Iran.

    Dizadji, A; Koohi-Habibi, M; Izadpanah, K; Dietrich, C; Mossahebi, G H; Winter, S

    2008-01-01

    A virus with flexuous rod-shaped particle morphology was found in samples from lettuce during a survey of viruses infecting lettuce in Tehran province in Iran. This virus was subjected to a complete analysis of its biological and molecular features. The entire nucleotide sequence of the virus was determined, revealing a polyadenylated ssRNA genome consisting of 7,212 nucleotides [without poly (A) tail] and possessing an organization typical for potexviruses. Comparative genome analysis showed that the lettuce virus is closely related to Alstroemeria virus X, narcissus mosaic virus and asparagus virus 3. Based on particle morphology, physico-chemical properties and the complete genome sequence, this virus is a member of a new species in the genus Potexvirus, for which the name lettuce virus X (LeVX) is proposed. Biological assays using an infectious cDNA clone and a wild-type isolate of LeVX revealed that the virus, despite reaching high concentrations in all lettuce cultivars tested, does not cause symptoms in lettuce. PMID:18807116

  18. 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

    S.R. Marchi

    2009-06-01

    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 μL per plant and the unitary deposits where estimated in μL 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.

  19. Ladybugs and Lettuce Leaves. Teachers' Manual.

    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…

  20. Breeding lettuce for fresh-cut processing

    Lettuce is increasingly consumed in fresh-cut packaged salads. New cultivars specifically bred for this use can enhance production and processing efficiency and extend shelf life. Cultivars with novel head architectures and leaf traits are being released by private and public breeding programs with ...

  1. Are Radishes Really Allelopathic to Lettuce?

    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)

  2. Partial aphid resistance in lettuce negatively affects parasitoids.

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

    2014-10-01

    This study investigated the effects of partial plant resistance on the lettuce aphid Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae), a major pest of cultivated lettuce (Lactuca sativa L.), and one of its parasitoids, Aphidius ervi Haliday (Hymenoptera: Braconidae). Aphids were reared on susceptible (L. sativa variety Estival; S) or partially resistant (Lactuca serriola L. PI 491093; PR) lettuce, and next parasitized by A. ervi females. Fitness proxies were measured for both aphids and parasitoids. Developmental time to adult stage took longer for alate and apterous aphids (an average of 3.5 and 1.5 additional days, respectively) on PR than on S lettuce, and fecundity of alate aphids reared on PR lettuce was reduced by 37.8% relative to those reared on S lettuce. Size (tibia length) and weight of aphids reared on PR lettuce were lower than for aphids reared on S lettuce from the third and second instar onward, respectively. Parasitism of aphids reared on PR plants resulted in lower parasitoid offspring emergence (-49.9%), lower adult female (-30.3%) and male (-27.5%) weight, smaller adult female (-17.5%) and male (-11.9%) size, and lower female fecundity (37.8% fewer eggs) than when parasitoids developed from aphids reared on S plants. Our results demonstrate that partial aphid resistance in lettuce negatively affects both the second and third trophic levels. Host plant resistance in cultivated lettuce may therefore create an ecological sink for aphid parasitoids. PMID:25197882

  3. USE OF REJECT BRINE FROM DESALINATION ON DIFFERENT DEVELOPMENT STAGES OF HYDROPONIC LETTUCE

    NILDO DA SILVA DIAS

    2011-01-01

    Full Text Available In order to evaluated the impact of the high salinity reject brine from reverse osmosis desalination on hydroponics lettuce cultivated in greenhouse an investigation was carried out in Mossoro, Northeast of Brazil (5º11'S, 37º20'O and 18m above sea. Two lettuce cultivars ('Verônica' and 'Babá de verão' were cultivated with a basic nutrient solution with 1.1 dS m-1 (control during the crop cycle (1-28 days after transplanting - DAT - T0 and with basic nutrient solution containing 50% of the reject water from desalinization with 4.8 dS m-1 exposed during 1-7, 21-28, 7-14 e 1-28 DAT (T1, T2, T3 and T4, respectively. The addition of 50% of brine reject from desalination into the hydroponic nutrient solution allows grow only 'Verônica' lettuce with no reduction in fresh biomass. This lettuce cultivar shows to be more tolerant to salinity for all exposure time with reject brine in the nutrition solution, despite the fact that 'Babá de Verão' cultivar is more productive.

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

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

    2016-02-01

    The uptake of polybrominated diphenyl ethers (PBDEs) by carrot and lettuce was investigated. Degradation of PBDEs in soil in the absence of the plants was discarded. Different carrot (Nantesa and Chantenay) and lettuce (Batavia Golden Spring and Summer Queen) varieties were grown in fortified or contaminated compost-amended soil mixtures under greenhouse conditions. After plant harvesting, roots (core and peel) and leaves were analyzed separately for carrot, while for lettuce, leaves and hearts were analyzed together. The corresponding bioconcentration factors (BCFs) were calculated. In carrots, a concentration gradient of 2,2',3,4,4',5'-hexabromodiphenyl ether (BDE-138) became evident that decreased from the root peel via root core to the leaves. For decabromodiphenyl ether (BDE-209) at the low concentration level (7 and 20 ng g(-1)), the leaves incorporated the highest concentration of the target substance. For lettuce, a decrease in the BCF value (from 0.24 to 0.02) was observed the higher the octanol-water partition coefficient, except in the case of BDE-183 (BCF = 0.51) and BDE-209 (BCF values from 0.41 to 0.74). Significant influence of the soils and crop varieties on the uptake could not be supported. Metabolic debromination, hydroxylation or methylation of the target PBDEs in the soil-plant system was not observed. PMID:26498966

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

    B Nomanpour

    2012-04-01

    Full Text Available 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 protocol consists of 3 levels to disinfect the fruits and vegetables. The procedure was as follows: first washing stage. The leaves of leafy vegetables washed with tap water, second stage, separation of helminth eggs by 3 to 5 droplets of detergent per liter for 5 min; third stage, disinfection of vegetables by calcium hypochlorite solution (with 200 mg/l free chlorine for 5 min; and finally the disinfected vegetables were washed with tap water.Results: The average initial levels of total coliform and fecal coliform in the samples were 3.36 log10 cfu/g and 2.31 log10 cfu/g, respectively. Helminth eggs were not detected in any of the samples tested. The efficiency of total coliform and fecal coliform removal were 78.1% (0.75 log10cfu/g and 79.6% (0.67 log10cfu/g, respectively, after washing. This increased up to 94.8(1.44 log10cfu/g and 98.5% (1.90 log10cfu/g after the use of detergent. Chlorine disinfection rose these amounts up to 98.3% (2.18 log10cfu/g and 100% (2.31 log10cfu/g, respectively.Conclusion: By applying the protocol large parts of microorganisms existing on lettuce have indeed been removed.

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

    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

  7. Regenerative Life Support Systems Test Bed performance - Lettuce crop characterization

    Barta, Daniel J.; Edeen, Marybeth A.; Eckhardt, Bradley D.

    1992-01-01

    System performance in terms of human life support requirements was evaluated for two crops of lettuce (Lactuca sative cv. Waldmann's Green) grown in the Regenerative Life Support Systems Test Bed. Each crop, grown in separate pots under identical environmental and cultural conditions, was irrigated with half-strength Hoagland's nutrient solution, with the frequency of irrigation being increased as the crop aged over the 30-day crop tests. Averaging over both crop tests, the test bed met the requirements of 2.1 person-days of oxygen production, 2.4 person-days of CO2 removal, and 129 person-days of potential potable water production. Gains in the mass of water and O2 produced and CO2 removed could be achieved by optimizing environmental conditions to increase plant growth rate and by optimizing cultural management methods.

  8. Agronomic efficiency of intercropping tomato and lettuce

    Arthur B. Cecílio Filho

    2011-09-01

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

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

    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

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

    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

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

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

    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.

  13. Influence of nitrogen and phosphorus sources on mycorrhizal lettuces under organic farming

    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

  14. Production of iceberg lettuce using mulches

    Verdial Marcelo Fontanetti

    2001-01-01

    Full Text Available Mulches bring several benefits to lettuce cultivation. This work evaluated the effect of mulches on the cultivation of iceberg lettuce, cv. Lucy Brown. The treatment plots were: 1- no mulch and no weed control (control; 2- no mulch and weed control every 15 days; 3- sugarcane bagasse mulch of 2 cm thickness; 4- black plastic mulch; 5- double-faced plastic mulch (silver/black. Data were collected in regard to plant cycle when in the field, amount of chlorophyll in the leaves, productivity (individual weight per head and amount of nutrients absorbed by the leaves. Double-faced plastic mulch provides the highest productivity and the highest values for the amount of chlorophyll, nitrogen, phosphorus, sulfur, boron and iron accumulation in the leaves.

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

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

    Pęczuła 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.

  17. Effects of soil texture and drought stress on the uptake of antibiotics and the internalization of Salmonella in lettuce following wastewater irrigation.

    Zhang, Yuping; Sallach, J Brett; Hodges, Laurie; Snow, Daniel D; Bartelt-Hunt, Shannon L; Eskridge, Kent M; Li, Xu

    2016-01-01

    Treated wastewater is expected to be increasingly used as an alternative source of irrigation water in areas facing fresh water scarcity. Understanding the behaviors of contaminants from wastewater in soil and plants following irrigation is critical to assess and manage the risks associated with wastewater irrigation. The objective of this study was to evaluate the effects of soil texture and drought stress on the uptake of antibiotics and the internalization of human pathogens into lettuce through root uptake following wastewater irrigation. Lettuce grown in three soils with variability in soil texture (loam, sandy loam, and sand) and under different levels of water stress (no drought control, mild drought, and severe drought) were irrigated with synthetic wastewater containing three antibiotics (sulfamethoxazole, lincomycin and oxytetracycline) and one Salmonella strain a single time prior to harvest. Antibiotic uptake in lettuce was compound-specific and generally low. Only sulfamethoxazole was detected in lettuce with increasing uptake corresponding to increasing sand content in soil. Increased drought stress resulted in increased uptake of lincomycin and decreased uptake of oxytetracycline and sulfamethoxazole. The internalization of Salmonella was highly dependent on the concentration of the pathogen in irrigation water. Irrigation water containing 5 Log CFU/mL Salmonella resulted in limited incidence of internalization. When irrigation water contained 8 Log CFU/mL Salmonella, the internalization frequency was significantly higher in lettuce grown in sand than in loam (p = 0.009), and was significantly higher in lettuce exposed to severe drought than in unstressed lettuce (p = 0.049). This work demonstrated how environmental factors affected the risk of contaminant uptake by food crops following wastewater irrigation. PMID:26552531

  18. Investigation of Pb species in soils, celery and duckweed by synchrotron radiation X-ray absorption near-edge structure spectrometry

    Luo, Liqiang; Shen, Yating; Liu, Jian; Zeng, Yuan

    2016-08-01

    The Pb species play a key role in its translocation in biogeochemical cycles. Soils, sediments and plants were collected from farmlands around Pb mines, and the Pb species in them was identified by X-ray absorption near-edge structure spectrometry. In soils, Pb5(PO4)3Cl and Pb3(PO4)2 were detected, and in sediments, Pb-fulvic acids (FAs) complex was identified. A Pb complex with FA fragments was also detected in celery samples. We found that (1) different Pb species were present in soils and sediments; (2) the Pb species in celery, which was grown in sediments, was different from the species present in duckweed, which grew in water; and (3) a Pb-FA-like compound was present in celery roots. The newly identified Pb species, the Pb-FA-like compound, may play a key role in Pb tolerance and translocation within plants.

  19. Rhizonin A from Burkholderia sp. KCTC11096 and Its Growth Promoting Role in Lettuce Seed Germination

    Sang-Mo Kang

    2012-07-01

    Full Text Available We isolated and identified a gibberellin-producing Burkholderia sp. KCTC 11096 from agricultural field soils. The culture filtrate of plant growth promoting rhizobacteria (PGPR significantly increased the germination and growth of lettuce and Chinese cabbage seeds. The ethyl acetate extract of the PGPR culture showed significantly higher rate of lettuce seed germination and growth as compared to the distilled water treated control. The ethyl acetate fraction of the Burkholderia sp. was subjected to bioassay-guided isolation and we obtained for the first time from a Burkholderia sp. the plant growth promoting compound rhizonin A (1, which was characterized through NMR and MS techniques. Application of various concentrations of 1 significantly promoted the lettuce seed germination as compared to control.

  20. Use of Propolis in the Sanitization of Lettuce

    Xesús Feás

    2014-07-01

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

  1. Laboratory to pilot scale: Microwave extraction for polyphenols lettuce.

    Périno, Sandrine; Pierson, Jean T; Ruiz, Karine; Cravotto, Giancarlo; Chemat, Farid

    2016-08-01

    Microwave hydrodiffusion and gravity (MHG) technique has been applied to pilot-scale solvent-free microwave extraction (SFME) of polyphenols from Lettuce sativa. Following the dictates of green extraction and with the aim to save time and energy, the lab-scale knowledge on SFME was exploited for the development of a pilot-scale process. The investigation entailed the optimization of all main parameters (temperature, time, extracted water volume, etc.) and we showed that the polyphenols composition profile under SFME was similar to the classic methods though a bit lower in total content. The energy consumption in the optimized procedure (30min) was 1W/g of fresh matrix. PMID:26988482

  2. Posidonia residues can be used as organic mulch and soil amendment for lettuce and tomato production

    Grassi, Francesco; Mastrorilli, Marcello; Mininni, Carlo; Parente, Angelo; Santino, Angelo; Scarcella, Marcello; Santamaria, Pietro

    2015-01-01

    There is a need for sustainable fertilizers because common mineral fertilizers are increasingly costly and often induce water and air pollution. For instance, seagrass compost could be used as fertilizer in the coastal areas of the Mediterranean, thus also solving the issue of beached residues. Here, we studied organic fertilization by application of seagrass-based compost in a tomato and lettuce crop succession. Composts were made of posidonia and yard wastes at 1/4 w/w fresh weight ratio. C...

  3. USE OF PELLETED LETTUCE SEEDS IN BIOABAILABILITY STUDIES

    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...

  4. USE OF PELLETED LETTUCE SEEDS IN BIOAVAILABILITY STUDIES

    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...

  5. Detection of lettuce discoloration using hyperspectral reflectance imaging

    Rapid visible/near-infrared (VNIR) hyperspectral imaging methods, employing both a single waveband algorithm and multi-spectral algorithms, were developed in order to classify the discoloration of lettuce. Reflectance spectra for sound and discolored lettuce surfaces were extracted from hyperspectra...

  6. Microcystin-LR bioaccumulation and depuration kinetics in lettuce and arugula: Human health risk assessment.

    Cordeiro-Araújo, Micheline Kézia; Chia, Mathias Ahii; Arruda-Neto, João Dias de Toledo; Tornisielo, Valdemar Luiz; Vilca, Franz Zirena; Bittencourt-Oliveira, Maria do Carmo

    2016-10-01

    Microcystin-LR (MC-LR) is one of the most toxic and common microcystins (MCs) variant found in aquatic ecosystems. Little is known about the possibility of recovering microcystins contaminated agricultural crops. The objectives of this study were to determine the bioaccumulation and depuration kinetics of MC-LR in leaf tissues of lettuce and arugula, and estimate the total daily intake (ToDI) of MC-LR via contaminated vegetables by humans. Arugula and lettuce were irrigated with contaminated water having 5 and 10μgL(-1) of MC-LR for 7days (bioaccumulation), and subsequently, with uncontaminated water for 7days (depuration). Quantification of MC-LR was performed by LC-MS/MS. The one-compartment biokinetic model was employed for MC-LR bioaccumulation and depuration data analysis. MC-LR was only accumulated in lettuce. After 7days of irrigation with uncontaminated water, over 25% of accumulated MC-LR was still retained in leaf tissues of plants treated with 10μgL(-1) MC-LR. Total daily toxin intake by adult consumers (60kg-bw) exceeded the 0.04μgMC-LRkg(-1) limit recommended by WHO. Bioaccumulation was found to be linearly proportional to the exposure concentration of the toxin, increasing over time; and estimated to become saturated after 30days of uninterrupted exposure. On the other hand, MC-LR depuration was less efficient at higher exposure concentrations. This is because biokinetic half-life calculations gave 2.9 and 3.7days for 5 and 10μgL(-1) MC-LR treatments, which means 29-37days are required to eliminate the toxin. For the first time, our results demonstrated the possibility of MC-LR decontamination of lettuce plants. PMID:27267723

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

    Mara Lígia Biazotto Bachelli

    2013-09-01

    Full Text Available Lettuce is a leafy vegetable widely used in industry for minimally processed products, in which the step of sanitization is the crucial moment for ensuring a safe food for consumption. Chlorinated compounds, mainly sodium hypochlorite, are the most used in Brazil, but the formation of trihalomethanes from this sanitizer is a drawback. Then, the search for alternative methods to sodium hypochlorite has been emerging as a matter of great interest. The suitability of chlorine dioxide (60 mg L-1/10 min, peracetic acid (100 mg L-1/15 min and ozonated water (1.2 mg L-1 /1 min as alternative sanitizers to sodium hypochlorite (150 mg L-1 free chlorine/15 min were evaluated. Minimally processed lettuce washed with tap water for 1 min was used as a control. Microbiological analyses were performed in triplicate, before and after sanitization, and at 3, 6, 9 and 12 days of storage at 2 ± 1 ºC with the product packaged on LDPE bags of 60 µm. It was evaluated total coliforms, Escherichia coli, Salmonella spp., psicrotrophic and mesophilic bacteria, yeasts and molds. All samples of minimally processed lettuce showed absence of E. coli and Salmonella spp. The treatments of chlorine dioxide, peracetic acid and ozonated water promoted reduction of 2.5, 1.1 and 0.7 log cycle, respectively, on count of microbial load of minimally processed product and can be used as substitutes for sodium hypochlorite. These alternative compounds promoted a shelf-life of six days to minimally processed lettuce, while the shelf-life with sodium hypochlorite was 12 days.

  8. 7 CFR 319.56-24 - Lettuce and peppers from Israel.

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Lettuce and peppers from Israel. 319.56-24 Section 319... Lettuce and peppers from Israel. (a) Lettuce may be imported into the United States from Israel without... applicable provisions of this subpart. (1) Growing conditions. (i) The lettuce must be grown in...

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

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

  10. The morphology, physiology and nutritional quality of lettuce grown under hypobaria and hypoxia

    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.

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

    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)

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

    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

  13. Growth of Three Lettuce Cultivars in NASA's HDU PEM During the 2010 DRATS Test

    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

  14. Effects of soil potential on lettuce growth and water use efficiency under drip irrigation in semi-humid regions of north China%华北地区滴灌控制基质势对生菜产量和水分利用的影响

    蒋树芳; 万书勤; 康跃虎; 裴亮; 刘士平; 曲强

    2011-01-01

    利用三年试验资料研究了华北地区滴灌条件下,不同基质势处理(- 10 kPa,-20 kPa,-30 kPa,-40 kPa,-50kPa)对结球生菜产量、水分利用效率(WUE)及灌溉水利用效率(IWUE)等的影响.结果表明:随着滴头正下方0.2m深度处土壤基质势控制的降低,整个生育期结球生菜的灌溉水量、累计耗水量明显减少,而水分利用效率和灌溉水利用效率随着土壤基质势控制的降低明显升高,但不同处理生菜总产量无显著差异.三年监测数据表明,受生长期降雨影响,大部分时间土壤基质势实际都维持在-30kPa以上.因此,露地滴灌种植生菜,缓苗后,可通过控制滴头正下方0.2m深度处土壤基质势下限高于- 30 kPa来指导灌溉.%Three years experiments were carried out to investigate the effects of different soil matric potential (from - 10 to -50 kPa) on the lettuce growth and water use efficiency under drip irrigation condition in North China. The results showed that with the soil matric potential decresesed at 0. 2 m depth immediately under drip emitters the irrigation amount and the accumulative consumed water in whole growing were obviously reduced, but the irrigation water use efficiency obviously increased and didn' t affect the total yield significantly. The observation results during three years showed that the majority of soil matric potential was distributed above -30kPa. So in north China plan, for field -grown lettuce, it can be used to schedule irrigation by controlling the soil matric potential at 0. 2 m depth immediately under drip emitters above -30 kPa.

  15. 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

    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)

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

    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.

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

    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....

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

    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)

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

    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 μM. High accumulation of cadmium was observed (12,320 ± 2155 μg g-1 at 500 μM 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 μM 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

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

    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.

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

    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.

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

    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

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

    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

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

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

    2013-01-01

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

  5. 赤霉素对生菜保鲜的品质影响研究%Effects of Gibberellin on the Quality of Lettuce in Storage

    焦莉; 王大平

    2013-01-01

    [Objective]To find a simple and cheap way for lettuce fresh-keeping. [ Method] With lettuce as material, the effects of GA3 treatments by different density (0,5, 15, 25, 35 mg/L) on the quality of lettuce were studied. [ Result] Compared with the control, the results showed that GA3 treatments could keep good appearance quality of lettuce, decrease the loss of water, Vc content and chlorophyll content, stop the rise of nitrate content in lettuce storage, and prolong the storage period of lettuce. The results also indicated that the 25 mg/L GA3 treatments was the best. [Conclusion] The study provides reference basis for fresh-keeping of lettuce.%[目的]为生菜的保鲜寻求一种简单、便宜的方法.[方法]以生菜为试材,用5、15、25、35 mg/L的赤霉素溶液进行处理,以清水处理为对照,研究了赤霉素对生菜保鲜的品质影响.[结果]与对照相比,试验用赤霉素浓度均可以保持生菜贮藏过程中的外观品质,减少生菜中水分、VC含量和叶绿素含量的损失,阻止亚硝酸盐含量的上升,能够延长生菜的贮藏寿命,提高其贮藏品质,25 mg/L GA3处理的保鲜效果最为明显.[结论]研究可为生菜的保鲜提供参考依据.

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

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

    2014-01-01

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

  7. A SEDIMENT TOXICITY METHOD USING LEMNA MINOR, DUCKWEED

    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 ...

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

    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

  9. 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

    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 ...

  10. Common duckweed (Lemna minor is a versatile high-throughput infection model for the Burkholderia cepacia complex and other pathogenic bacteria.

    Euan L S Thomson

    Full Text Available 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 Galleria mellonella (Greater wax moth larvae, a previously established Bcc infection model, a duckweed survival assay was developed and used to determine LD50 values. A strong correlation (R(2 = 0.81 was found between the strains' virulence ranks in the two infection models, suggesting conserved pathways in these vastly different hosts. To broaden the application of the duckweed model, enteropathogenic Escherichia coli (EPEC and five isogenic mutants with previously established LD50 values in the larval model were tested against duckweed, and a strong correlation (R(2 = 0.93 was found between their raw LD50 values. Potential virulence factors in B. cenocepacia K56-2 were identified using a high-throughput screen against single duckweed plants. In addition to the previously characterized antifungal compound (AFC cluster genes, several uncharacterized genes were discovered including a novel lysR regulator, a histidine biosynthesis gene hisG, and a gene located near the gene encoding the recently characterized virulence factor SuhB(Bc. Finally, to demonstrate the utility of this model in therapeutic applications, duckweed was rescued from Bcc infection by treating with bacteriophage at 6-h intervals. It was observed that phage application became ineffective at a timepoint that coincided with a sharp increase in bacterial invasion of plant tissue. These results indicate that common duckweed can serve as an effective infection model for the investigation of bacterial

  11. Survey of the total fatty acid and triacylglycerol composition and content of 30 duckweed species and cloning of a Δ6-desaturase responsible for the production of γ-linolenic and stearidonic acids in Lemna gibba

    Yan, Yiheng; Candreva, Jason; Shi, Hai; Ernst, Evan; Martienssen, Robert; Schwender, Jorg; Shanklin, John

    2013-01-01

    Background Duckweeds, i.e., members of the Lemnoideae family, are amongst the smallest aquatic flowering plants. Their high growth rate, aquatic habit and suitability for bio-remediation make them strong candidates for biomass production. Duckweeds have been studied for their potential as feedstocks for bioethanol production; however, less is known about their ability to accumulate reduced carbon as fatty acids (FA) and oil. Results Total FA profiles of thirty duckweed species were analysed t...

  12. Efficacy of adding detergents to sanitizer solutions for inactivation of Escherichia coli O157:H7 on Romaine lettuce.

    Keskinen, Lindsey A; Annous, Bassam A

    2011-06-30

    Numerous Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh lettuce. The development of effective and easily implemented wash treatment could reduce such incidents. The purpose of this study was to evaluate the addition of food-grade detergents to sanitizer solutions for inactivation of E. coli O157:H7 on Romaine lettuce. Freshly-cut leaves of Romaine lettuce were dip-inoculated to achieve a final cell concentration of 7.8±0.2 log CFU/g, air-dried for 2h, and stored overnight at 4 °C. Leaves were then washed for 2 min in an experimental short chain fatty acid formulation (SCFA) or in one of the following solutions with or without 0.2% dodecylbenzenesulfonic acid or 0.2% sodium 2-ethyl hexyl sulfate: 1) deionized water; 2) 100 ppm chlorine dioxide; 3) 100 ppm chlorine; and 4) 200 ppm chlorine. Following wash treatment, samples were blended in neutralizing buffer (1:3) and surface plated on the selective media CT-SMAC. The efficacy of wash treatments, with or without the detergents, in inactivating E. coli O157:H7 cells on lettuce leaves were not significantly different. The most effective wash solution was SCFA, which was capable of reducing E. coli O157:H7 populations by more than 5 log CFU/g. The rest of the wash treatments resulted in a population reduction of less than 1 log CFU/g. The effectiveness of SCFA surpasses that of other sanitizer treatments tested in this study and requires further research to optimize treatments to preserve lettuce quality. Conventional detergents did not enhance the efficacy of any of the wash treatments tested during this study. PMID:21529976

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

    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)

  14. Characteristics of a Lettuce mosaic virus Isolate Infecting Lettuce in Korea

    Seungmo Lim

    2014-06-01

    Full Text Available Lettuce mosaic virus (LMV causes disease of plants in the family Asteraceae, especially lettuce crops. LMV isolates have previously been clustered in three main groups, LMV-Yar, LMV-Greek and LMVRoW. The first two groups, LMV-Yar and LMV-Greek, have similar characteristics such as no seed-borne transmission and non-resistance-breaking. The latter one, LMV-RoW, comprising a large percentage of the LMV isolates contains two large subgroups, LMV-Common and LMV-Most. To date, however, no Korean LMV isolate has been classified and characterized. In this study, LMV-Muju, the Korean LMV isolate, was isolated from lettuce showing pale green and mottle symptoms, and its complete genome sequence was determined. Classification method of LMV isolates based on nucleotide sequence divergence of the NIb-CP junction showed that LMV-Muju was categorized as LMV-Common. LMV-Muju was more similar to LMV-O (LMV-Common subgroup than to LMV-E (LMV-RoW group but not LMV-Common subgroup even in the amino acid domains of HC-Pro associated with pathogenicity, and in the CI and VPg regions related to ability to overcome resistance. Taken together, LMV-Muju belongs to the LMV-Common subgroup, and is expected to be a seed-borne, non-resistance-breaking isolate. According to our analysis, all other LMV isolates not previously assigned to a subgroup were also included in the LMV-RoW group.

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

    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.

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

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

    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...

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

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

    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...

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

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

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

    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

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

    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...

  1. Detection of Lettuce Discoloration Using Hyperspectral Reflectance Imaging

    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.

  2. 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

    S.R. Marchi

    2011-03-01

    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.

  3. Improvement of nutritional quality of greenhouse-grown lettuce by arbuscular mycorrhizal fungi is conditioned by the source of phosphorus nutrition.

    Baslam, Marouane; Pascual, Inmaculada; Sánchez-Díaz, Manuel; Erro, Javier; García-Mina, José María; Goicoechea, Nieves

    2011-10-26

    The improvement of the nutritional quality of lettuce by its association with arbuscular mycorrhizal fungi (AMF) has been recently reported in a previous study. The aim of this research was to evaluate if the fertilization with three P sources differing in water solubility affects the effectiveness of AMF for improving lettuce growth and nutritional quality. The application of either water-soluble P sources (Hewitt's solution and single superphosphate) or the water-insoluble (WI) fraction of a "rhizosphere-controlled fertilizer" did not exert negative effects on the establishment of the mycorrhizal symbiosis. AMF improved lettuce growth and nutritional quality. Nevertheless, the effect was dependent on the source of P and cultivar. Batavia Rubia Munguía (green cultivar) benefited more than Maravilla de Verano (red cultivar) in terms of mineral nutrients, total soluble sugars, and ascorbate contents. The association of lettuce with AMF resulted in greater quantities of anthocyanins in plants fertilized with WI, carotenoids when plants received either Hewitt's solution or WI, and phenolics regardless of the P fertilizer applied. PMID:21913649

  4. Control of lettuce bottom rot by isolates of Trichoderma spp

    Zayame Vegette Pinto

    2014-06-01

    Full Text Available Bottom rot, caused by Rhizoctonia solani AG 1-IB, is an important disease affecting lettuce in Brazil, where its biological control with Trichoderma was not developed yet. The present study was carried out with the aim of selecting Trichoderma isolates to be used in the control of lettuce bottom rot. Forty-six Trichoderma isolates, obtained with baits containing mycelia of the pathogen, were evaluated in experiments carried out in vitro and in vivo in a greenhouse in two steps. In the laboratory, the isolates were evaluated for their capabilities of parasitizing and producing toxic metabolic substances that could inhibit the pathogen mycelial growth. In the first step of the in vivo experiments, the number and the dry weight of lettuce seedlings of the cultivar White Boston were evaluated. In the second step, 12 isolates that were efficient in the first step and showed rapid growth and abundant sporulation in the laboratory were tested for their capability of controlling bottom rot in two repeated experiments, and had their species identified. The majority of the isolates of Trichoderma spp. (76% showed high capacity for parasitism and 50% of them produced toxic metabolites capable of inhibiting 60-100% of R. solani AG1-IB mycelial growth. Twenty-four isolates increased the number and 23 isolates increased the dry weight of lettuce seedlings inoculated with the pathogen in the first step of the in vivo experiments.In both experiments of the second step, two isolates of T. virens, IBLF 04 and IBLF 50, reduced the severity of bottom rot and increased the number and the dry weight of lettuce seedlings inoculated with R. solani AG1-IB. These isolates had shown a high capacity for parasitism and production of toxic metabolic substances, indicating that the in vitro and in vivo steps employed in the present study were efficient in selecting antagonists to be used for the control of lettuce bottom rot.

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

    Józef Bąkowski; Helena Michalik; Marcin Horbowicz

    2013-01-01

    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. Lettuc...

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

    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

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

    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.

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

    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 (lettuce should be under a lower NaCl stress (<1000 ppm) for water cleaning in future BLSS.

  9. Use of a common laboratory glassware detergent improves recovery of Cryptosporidium parvum and Cyclospora cayetanensis from lettuce, herbs and raspberries.

    Shields, Joan M; Lee, Michelle Minjung; Murphy, Helen R

    2012-02-01

    The success of any protocol designed to detect parasitic protozoa on produce must begin with an efficient initial wash step. Cryptosporidium parvum and Cyclospora cayetanensis oocysts were seeded onto herbs, lettuces and raspberries, eluted with one of four wash solutions and the recovered number of oocysts determined via fluorescent microscopy. Recovery rates for fluorescein thiosemicarbazide labeled C. parvum oocysts seeded onto spinach and raspberries and washed with de-ionized water were 38.4 ± 10.1% and 34.9 ± 6.2%, respectively. Two alternative wash solutions viz. 1M glycine, pH 5.5 and a detachment solution were tested also using labeled C. parvum seeded spinach and raspberries. No statistically significant difference was noted in the recovery rates. However, a wash solution containing 0.1% Alconox, a laboratory glassware detergent, resulted in a significant improvement in oocyst recovery. 72.6 ± 6.6% C. parvum oocysts were recovered from basil when washed with 0.1% Alconox compared to 47.9 ± 5.8% using detachment solution. Also, C. cayetanensis oocysts were seeded onto lettuces, herbs and raspberries and the recovery using de-ionized water were compared to 0.1% Alconox wash: basil 17.5 ± 5.0% to 76.1 ± 14.0%, lollo rosso lettuce 38.3 ± 5.5% to 72.5 ± 8.1%, Tango leaf lettuce 45.9 ± 5.4% to 71.1 ± 7.8% and spring mix (mesclun) 39.8 ± 0.7% to 80.2 ± 11.3%, respectively. These results suggest that the use of Alconox in a wash solution significantly improves recovery resulting in the detection of these parasitic protozoa on high risk foods. PMID:22094179

  10. Effects of different nutrients solutions on nutrients concentration and some qualitative traits of lettuce in hydroponics system

    M. Safaei; J. Panahandeh; S.J. Tabatabaei; A.R. Motallebi Azar

    2015-01-01

    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 (Hoagl...

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

    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

  12. 赤霉素对生菜的保鲜研究%Preservation Test on Lettuce with Gibberellin

    张林青

    2009-01-01

    [Objective] The purpose was to research preservative effect of gibberellin ( GA_3) on lettuce. [Method] With Italian lettuce of bolting-resistance in whole year as tested material, GA_3 solution was set up as 4 concn. treatments (5, 10, 15, 20 mg/L) and clean water as control one, the lettuces were stored after being immersed by GA_3 solution with different concn. for 15 min, and each physiological index of lettuces were tested every other 4 d. [Result] Compared with the control one, the storage life of lettuces treated with GA_3 could be prolonged by 3 to 7 d, the contents of Vc, starch and chlorophyll were raised by 25.22% ~ 67. 12% , 3.19% ~ 29.16% and 14.44% ~ 29.7% resp. GA_3 treatment could effectively mitigate evaporation of water content of lettuce, inhibit decomposition and consumption of soluble sugar and starch, reduce the oxidized and decomposed speed of chlorophyll, and maintain the content of soluble solids. Among 4 treatments of concn. , the effect of 15 mg/L GA_3 treatment was the best, the storage life of lettuces was able to extend by 7 d, and falling degree of each index was much slower than the other concn. treatments. [Conclusion] GA_3 was capable of prolonging lettuce storage life and improving storage quality, so it had the evident preservation function.%[目的]研究赤霉素(GA_3)对生菜的保鲜作用.[方法]以意大利全年耐抽薹生菜为试材,GA_3溶液设4种浓度处理(5、10、15、20mg/L),清水为对照,浸泡生菜15 min后贮藏,之后每隔4 d测试生菜的各项生理指标.[结果]与对照相比,经GA_3处理生幕的贮藏寿命可延长3~7 d,Vc、淀粉和叶绿素含量分别提高25.22%~67.12%、3.19%~29.16%和14.44%~29.7%.GA_3处理可有效地减缓生莱含水量的蒸发,抑制可溶性糖和淀粉的分解消耗,降低叶绿素被氧化分解的速度,维持可溶性固形物的含量.4种浓度处理中,以15mg/L GA_3的处理效果最佳,生菜的贮藏寿命可延长7d,各项指标的下

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

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

    2010-01-01

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

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

    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,…

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

    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…

  16. Developing lettuce with improved quality for processed salads.

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

  17. Physiological mechanisms to cope with Cr(VI) toxicity in lettuce: can lettuce be used in Cr phytoremediation?

    Dias, Maria Celeste; Moutinho-Pereira, José; Correia, Carlos; Monteiro, Cristina; Araújo, Márcia; Brüggemann, Wolfgang; Santos, Conceição

    2016-08-01

    This research aims at identifying the main deleterious effects of Cr(VI) on the photosynthetic apparatus and at selecting the most sensitive endpoints related to photosynthesis. To achieve this goal, we used lettuce (Lactuca sativa), a sensible ecotoxicological crop model. Three-week-old plants were exposed to 0, 50, 150 and 200 mg L(-1) of Cr(VI). These concentrations ranged from levels admitted in irrigation waters to values found in several Cr industry effluents and heavily contaminated environments. After 30 days of exposure, plants accumulated Cr preferably in roots and showed nutritional impairment, with decreases of K, Mg, Fe and Zn in both roots and leaves. Cr(VI)-exposed plants showed decreased levels of chlorophyll (Chl) a and anthocyanins, as well as decreased effective quantum yield of photostystem II (ΦPSII) and photochemical Chl fluorescence quenching (qp), but increases in the non-photochemical Chl fluorescence quenching (NPQ) and in the de-epoxidation state (DEP) of the xanthophyll cycle. Net CO2 assimilation rate (P N ) and RuBisCO activity were mostly impaired in the highest Cr(VI) concentration tested. Concerning the final products of photosynthesis, starch content was not affected, while soluble sugar contents increased. These alterations were accompanied by a reduction in protein content and in plant growth. Our results support that endpoints related to the photosynthesis photochemical processes (ΦPSII and the qp) and the content of anthocyanins are sensitive predictors of Cr(VI) toxicity. The advantages of using these parameters as biomarkers for Cr toxicity in plants are discussed. Finally, we report that, despite showing physiological disorders, L. sativa plants survived and accumulated high doses of Cr, and their use in environmental/decontamination studies is open to debate. PMID:27130342

  18. The Effect of Anaerobic and Aerobic Fish Sludge Supernatant on Hydroponic Lettuce

    Simon Goddek

    2016-06-01

    Full Text Available The mobilization of nutrients from fish sludge (i.e., feces and uneaten feed plays a key role in optimizing the resource utilization and thus in improving the sustainability of aquaponic systems. While several studies have documented the aerobic and anaerobic digestion performance of aquaculture sludge, the impact of the digestate on plant growth has yet to be understood. The present study examines the impact of either an aerobic or an anaerobic digestion effluent on lettuce plant growth, by enriching a mixture of aquaculture and tap water with supernatants from both aerobic and anaerobic batch reactors. The lettuce plants grown in the hydroponic system supplied with supernatant from an anaerobic reactor had significantly better performance with respect to weight gain than both, those in the system where supernatant from the aerobic reactor was added, as well as the control system. It can be hypothesized that this effect was caused by the presence of NH4+ as well as dissolved organic matter, plant growth promoting rhizobacteria and fungi, and humic acid, which are predominantly present in anaerobic effluents. This study should therefore be of value to researchers and practitioners wishing to further develop sludge remineralization in aquaponic systems.

  19. Standardization of a method for the detection of helminth eggs and larvae in lettuce.

    Matosinhos, F C; Valenzuela, V C; Silveira, J A; Rabelo, E M

    2016-05-01

    Despite reports that food-borne parasitic infections have been increasing worldwide, the methodologies employed to detect food contamination by helminths are still largely based on methodologies used to detect these pathogens in feces and water. This study sought to improve the diagnosis of parasitic contaminants in lettuce by standardizing a method for detecting helminth eggs and larvae and estimating their percentage of recovery. Sanitized lettuces were artificially contaminated with different amounts of Ascaris suum and hookworm eggs and larvae. To standardize the method, we tested liquid extractors, vegetable washing steps, and spontaneous sedimentation times. Higher percentages of egg and larvae recovery were obtained using 1 M glycine as the liquid extractor, manual shaking for 3 min and 2 h of sedimentation. Five different levels of artificial contamination (ten replicates each; n = 50) were tested using these standardized conditions, yielding an average recovery of 62.6 % (±20.2), 51.9 % (±20.0), and 50.0 % (±27.3) for A. suum eggs, hookworm eggs, and larvae, respectively. Tests were performed with a different matrix to evaluate the performance of the method. Furthermore, collaborative analytical studies performed by different laboratories produced satisfactory results. The method for the identification of helminth eggs and larvae proposed in this study proved to be simpler and more efficient than previously published procedures, thereby demonstrating its potential contribution to health surveillance and epidemiological studies. PMID:26786833

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

    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

  1. Lettuce necrotic leaf curl virus, a new plant virus infecting lettuce and a proposed member of the genus Torradovirus

    Verbeek, M.; Dullemans, A.M.; Raaij, van H.M.G.; Verhoeven, J.Th.J.; Vlugt, van der R.A.A.

    2014-01-01

    A new virus was isolated from a lettuce plant grown in an open field in the Netherlands in 2011. This plant was showing conspicuous symptoms that consisted of necrosis and moderate leaf curling. The virus was mechanically transferred to indicator plants, and a total RNA extract of one of these indic

  2. Ethylene evolution and endo-beta-mannanase activity during lettuce seed germination at high temperature Evolução de etileno e atividade da enzima endo-beta-mananase durante a germinação de sementes de alface sob altas temperaturas

    Warley Marcos Nascimento; Daniel James Cantliffe; Donald John Huber

    2004-01-01

    High temperatures during lettuce seed imbibition can delay or completely inhibit germination and the endosperm layer appears to restrict the radicle protrusion. The role of endo-beta-mannanase during lettuce seed germination at 35°C and the influence of ethylene in endo-beta-mannanase regulation were investigated. Seeds of 'Dark Green Boston' (DGB) and 'Everglades' (EVE) were germinated in water, or 10 mmol L-1 of 1-aminocyclopropane-1-carboxylic acid (ACC), or 10 mmol L-1 of aminoethoxyvinyl...

  3. 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

    Alexandre O. Gonçalves

    2005-12-01

    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.

  4. 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

    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...

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

    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 ...

  6. Factors important for the shelf-life of minimally processed lettuce

    Deza Durand, Karla Michelle

    The minimally processed vegetable industry has been increasing rapidly due to change in lifestyle. Both women and men work outside home and have less time to cook and need more convenience and time saving products, which also present fresh and healthy characteristics. Iceberg lettuce (Lactuca...... important for the shelf-life of minimally processed iceberg lettuce and to propose a new methodology to measure browning in cut lettuce. Browning has been pointed out as the main factor limitating shelf-life in cut lettuce. The problem becomes complex because browning of cut lettuce is difficult to measure....... A novel method using image analysis for the measurement of browning in minimally processed lettuce was developed and presented in paper I. The method used a flatbed scanner for image acquisition, colour dye patches for colour correction, and colour thresholding to quantify the browning, that was...

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

    Józef Bąkowski

    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.

  8. Safety of Novel Protein Sources (Insects, Microalgae, Seaweed, Duckweed, and Rapeseed) and Legislative Aspects for Their Application in Food and Feed Production

    Spiegel, van der M.; Noordam, M.Y.; Fels-Klerx, van der H.J.

    2013-01-01

    Novel protein sources (like insects, algae, duckweed, and rapeseed) are expected to enter the European feed and food market as replacers for animal-derived proteins. However, food safety aspects of these novel protein sources are not well-known. The aim of this article is to review the state of the

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

    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)

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

    Rosangela Dallemole-Giaretta

    2015-10-01

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

  11. Colonization of lettuce rhizosphere and roots by tagged Streptomyces

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

    2015-01-01

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

  12. Influence of initial pesticide concentrations and plant population density on dimethomorph toxicity and removal by two duckweed species.

    Dosnon-Olette, Rachel; Couderchet, Michel; El Arfaoui, Achouak; Sayen, Stéphanie; Eullaffroy, Philippe

    2010-04-15

    Aquatic plants take up, transform and sequester organic contaminants and may therefore be used in phytoremediation for the removal of pollutants from wastewaters. A better understanding of factors affecting the rate of contaminant uptake by aquatic plants is needed to improve engineered systems for removal of pollutants from wastewaters. This work focused on the influence of initial concentrations of pesticide and population density of plants on toxicity and uptake of the fungicide dimethomorph by two duckweed species. An increased sensitivity to dimethomorph was observed with increasing duckweed population density. Less light, due to crowding, may explain this higher sensitivity and reduced removal rate. A positive relationship was also found between toxicity or contaminant uptake and initial pesticide concentration with a maximal removal of 41 and 26 microg g(-1) fresh weight of dimethomorph (at 600 microg L(-1) of dimethomorph and an initial density of 0.10g E-flask(-1)) by Lemna minor and Spirodela polyrhiza, respectively. This research also indicated that these aquatic plants can efficiently eliminate organic contaminants and may ultimately serve as phytoremediation agents in the natural environment. PMID:20156640

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

    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

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

    Cleyton Teles Contreiras Paiva

    2016-08-01

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

  15. Effect of Gypsum Application on Enzymatic Browning Activity in Lettuce

    Prasit Chutichudet

    2009-01-01

    Full Text Available A comprehensive study to evaluate calcium, in terms of gypsum (CaSO4.2H2O by soil dressing application, on enzymatic browning activity of Polyphenol oxidase (PPO and internal qualities was tested on lettuce var. Grand Rapids under field conditions. A factorial in completely randomized design was arranged with four replications. The results showed that plants-treated with 50 mg kg-1 gypsum applied at 40 DAP had the maximal fresh weight of 25.83 g plant-1. The internal qualities of the lettuce at harvest showed that plants treated with 50 mg kg-1 gypsum had the maximal chlorophyll content (26.80 mg m-2, while all gypsum concentrations applied in this study, had less content of ascorbic acid than the control plants. Plants-treated with 100 mg kg-1 gypsum affected to the lowest level of PPO activity at week 3 after transplanting. Furthermore, gypsum application had no effect to biomass, leaf colour, the contents of phenolic and quinone in lettuce at harvesting stage.

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

    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

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

    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 ...

  18. 76 FR 50992 - Notice of Availability of a Pest Risk Analysis for the Importation of Shredded Lettuce From Egypt

    2011-08-17

    ... Importation of Shredded Lettuce From Egypt AGENCY: Animal and Plant Health Inspection Service, USDA. ACTION... risks associated with the importation into the continental United States of fresh shredded lettuce from... weeds via the importation of fresh shredded lettuce from Egypt. We are making the pest risk...

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

    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.

  20. Weed management in transplanted lettuce with Pendimethalin and S-metolachlor

    Few herbicides are available for use in lettuce and hand weeding is required for commercially acceptable weed control. More effective herbicides are needed. Here we report field evaluations of pendimethalin and S-metolachlor for weed control in transplanted lettuce. Pendimethalin was evaluated PRE a...

  1. Development of an assay for rapid detection of the lettuce downy mildew pathogen, Bremia lactucae

    Downy mildew of lettuce, caused by Bremia lactucae, causes chlorosis on leaves and adversely affects marketability. Though downy mildew on lettuce can be controlled by fungicide applications, it is costly to routinely apply fungicides to prevent the establishment of downy mildew. Repeated use of the...

  2. Factors affecting the survival of Bremia lactucae sporangia deposited on lettuce leaves

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

    2000-01-01

    Experiments to identify the factors affecting survival of Bremia lactucae sporangia after deposition on lettuce leaves were conducted in growth chambers and outdoors under ambient conditions. Lettuce seedlings at the four-leaf stage were inoculated with B. lactucae sporangia under dry conditions. Sp

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

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

    2006-01-01

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

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

    Zdravković Jasmina M.

    2014-01-01

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

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

    Jayasinghe, Guttila Y; Tokashiki, Yoshihiro; Kitou, Makato; Kinjo, Kazutoshi

    2008-12-01

    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 shoot fresh weight, shoot dry weight, root fresh weight, root dry weight and number of leaves per plant of the lettuce grown in the 1 : 10 mixing ratio of SZ and OP were the highest, which showed increased values compared with that of PL by 11.56, 9.77, 3.48, 17.35 and 16.53%, respectively. The shoot fresh weight, shoot dry weight, root fresh weight, root dry weight and number of leaves per plant of the lettuce grown in the 1 : 10 mixing ratio of SZ and OP showed increased percentages compared with that of PE by 12.12, 11.37, 3.74, 23.66 and 17.50%, respectively. In addition, the growth and yield parameters of lettuce grown in the 1 : 3 mixing ratio and the OP did not show any significant difference with PL and PE but differed from the 1 : 10 mixing ratio. 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

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

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

  7. Evaluation of response of lettuce (Lactuca sativa L. to temperature and light stress

    Nidal Tabit Shaban

    2016-06-01

    Full Text Available The aim of the study was to assess the effect of irrigation water temperature and shading on the rate of photosynthesis and transpiration in four varieties of lettuce (Lactuca sativa L. – green foliage (‘Salakis’ and ‘Estony’ and red foliage (‘Lollo Rossa’ and ‘Nika’. During the production of seedlings in the greenhouse, two irrigation water temperature regimes (12 and 20°C were applied. After transplanting in the field plants were grown under three lighting systems (100, 70, and 50% of lighting in the open. The rates of photosynthesis and transpiration were measured at the end of the greenhouse period and 14 days after shading in the field using a Li 6400 infrared gas analyzer. In most varieties, cooling of the irrigation water was not found to have an effect on the rate of photosynthesis. Plants of all the varieties responded to the decrease in irrigation water temperature and to strong shading by reducing transpiration and increasing the water use efficiency. The ‘Salakis’ and ‘Estony’ plants have shown the best adaptability to the changing conditions and therefore they could be used successfully in the practice of extending vegetative growth.

  8. Adaptability test of lettuce to soil-like substrate in bioregenerative life support system

    Min, Yan; Liu, Professor Hong; Wenting, Fu

    Plant cultivation using soil-like substrate (SLS) is considered to be a feasible option for building up matter for biological turnover in bioregenerative life support system (BLSS) by many researchers. The characteristics of SLS are different from those of true soil therefore it is very important to study the adaptability of candidate crop to SLS in BLSS. This study was carried out in three successive steps to test the adaptability of lettuce (Lactuca sativa L.) to rice straw SLS in BLSS of China. First, six Chinese specific lettuce cultivars which were selected for Chinese advanced life support system were planted into the same rice straw SLS, which was to determine the more suitable plant cultivar to do the next experiment. The results showed that Sharp Leaf lettuce and Red lettuce were more suitable for SLS than other cultivars. Second, the possibility of increasing the crop yield on the SLS was conducted by changing the soil depth and plant density. Sharp Leaf lettuce and Red lettuce were used into this experiment in order to obtain the highest yield under the smallest soil volume and weight at the same light intensity. Crop edible biomass, crop nutrition content and photosynthetic characteristics were estimated during the experiment. Red lettuce obtained higher biomass and photosynthesis capacity. Lastly, the stability of planting system of lettuce and SLS was evaluated in the closed controlled system. Red lettuce would be the test plant. In this experiment different age lettuce groups would be planted together and gas exchange would be measured. In all of these experiments soil physical and chemical characteristics were also be measured which will be the basal data for further research.

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

    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...

  10. Lettuce image target clustering segmentation based on MFICSC algorithm%基于MFICSC 算法的生菜图像目标聚类分割

    孙俊; 武小红; 张晓东; 王艳; 高洪燕

    2012-01-01

    生菜图像目标分割是基于图像处理的生菜生理信息无损检测的前提.为了解决因生菜富含水分使得图像采集镜头反光而导致生菜叶片图像灰度分布不均的问题,该文采用一种修正的图像灰度均衡算法对生菜图像进行灰度均衡处理,应用混合模糊类间分离聚类算法(MFICSC)进行生菜图像目标分割,使总体类间距离最大化,能够同时生成模糊隶属度和典型值,对处理噪声数据和克服一致性聚类问题均表现良好.分别采用MFICSC算法和Otsu算法进行了生菜图像目标分割对比试验,结果表明MFICSC算法具有较好的聚类准确度,效果优于传统Otsu分割算法.%Lettuce image target segmentation is the premise of the nondestructive detection of lettuce physiological information based on image processing. Because lettuce contains more water, the camera len is likely to occur reflex, leading to uneven gray distribution of lettuce leaf image. A modified image equalization algorithm is used to equalize the image gray. In this paper, the mixed fuzzy inter-cluster separation clustering(MFICSC) is applied in lettuce image target segmentation, which can make the distance between classes be maximum on the whole and can produce the fuzzy memberships and possibilities simultaneously. MFICSC can overcome the noise sensitivity and the coincident clusters problem. In the test, the MFICSC algorithm and Otsu algorithm were applied to lettuce image target segmentation respectively. The test results show that the MFICSC algorithm has better clustering accuracy, and its segmentation effect is superior to the one of traditional Otsu algorithm.

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

    Wei-Chin Lin; Block, Glen S.

    2009-01-01

    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 temp...

  12. Preliminary studies on growth and fresh weight of lettuce (Lactuca sativa) as affected by clay pot irrigation and spacing.

    Abubakari, Abdul-Halim; Nyarko, George; Maalinyuur, Sheila

    2011-07-15

    An experiment (Completely Randomized Design) was set up to determine the effects of Clay Pot Sub-surface Irrigation (CPSI) and spacing on the growth and fresh weight of lettuce (Lactuca sativa). The treatments were: CPSI with spacing; 15 x 15 cm, 20 x 20 cm and 30 x 30 cm. Control treatments were Watering Can Irrigation (WCI) with the same spacing as above. Treatments were replicated three times given a total of 18 experimental units. Eighteen large enamel basins of 50/20 cm (diameter/height) were filled with good topsoil and a clay pot buried neck deep in each of the basins. Seedlings were planted in all the eighteen basins. Five Hundred mL of wastewater was applied daily to plants in each container having either clay pot or watering can treatment. Plant height increased from 2.50 to 4.25 cm within 6 Weeks after Transplanting (WAT) under CPSI and only increased from 2.14 to 2.99 cm under WCI. The CPSI also supported better leave growth and fresh weight. The fresh weight of lettuce increased almost two fold under 15 x 15 cm spacing compared to 20 x 20 and 30 x 30 cm. PMID:22308659

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

    Petersen, T. B.; Petersen, H. H.; Abaidoo, R. C.; 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 ...

  14. 浮萍净化N·P污染性能的研究%Study on the Purification Efficiency of Duckweed on Nitrogen and Phosphorus Pollutes

    于斌; 蔡树美; 郎莎莎; 钱晓晴

    2009-01-01

    [目的]明确浮萍净化污水TN和TP的特点,筛选高效净化氮磷有机污水的浮萍优化品种.[方法]从扬州市和昆山市各采样点选取的当地3种有代表性的浮萍品种为供试材料,以经稀释5倍、10倍的牛场厌氧废水为供试污水,设置5种不同浮萍对2种不同浓度污水的10组净化处理,在实验室条件下考察了不同浮萍品种对不同浓度污水氮和磷的净化效果.[结果]污水TN和TP浓度随浮萍处理时间(0~10 d)增加而持续降低;紫萍属浮萍对TN和TP的净化能力优于浮萍属浮萍;浮萍对稀释5倍的供试污水TN和TP的最大去除率分别为71.14%和81.00%;浮萍对稀释10倍的供试污水TN和TP的最大去除率分别为92.18%和91.33%.[结论]紫萍属浮萍可作为适合长江三角洲地区的高效净化氮磷有机污水的浮萍优化品种.%[Objective]The study aimed to definite the characters of duckweed for purifying TN and TP in sewage and screen the optimized duckweed variety that could purify N and P effectively in organic sewage. [Method]With 3 kinds of representative local duckweed varieties selected from the each sample place in Yangzhou City and Kunshan City resp. as the tested materials and the anaerobic wastewater diluted at 5 times and 10 times from the cattle Farm as the tested sewage,10 groups of purification treatments matching with 5 different duckweeds on 2 concn. of sewage were set up to investigate the effect of different duckweed variety on the purification effect of N and P in sewage with different concn. under lab condition. [Result]TN and TP concn. in the sewage were decreased constantly with the increase of duckweed treating time in 0-10 d. The purification ability of Spirodela Schleid on TN and TP was higher than that of Lemna L. The maximal removal rates of duckweed on TN and TP in sewage diluted at 5 times were 71.14% and 81.00% resp. and that in the sewage diluted 10 times were 92.18% and 91.33% resp. [Conclusion

  15. Escherichia coli O157:H7 stress and virulence gene expression on Romaine lettuce using comparative real-time PCR.

    Carey, Christine M; Kostrzynska, Magdalena; Thompson, Stacey

    2009-05-01

    Foodborne outbreaks attributed to the contamination of fresh produce with Escherichia coli O157:H7 are a growing concern. In particular, leafy-green vegetables, including lettuce and spinach, are susceptible to contamination by irrigation water, manure, and food processing and storage practices. The survival of E. coli O157:H7 and natural microflora on Romaine lettuce stored at 4 degrees C and 15 degrees C over a 9-day period was evaluated by plate counts. A two-step reverse-transcription comparative quantitative real-time PCR assay was employed to evaluate expression of genes coding for the A subunit of Shiga-toxin 1 and 2 (stx1A and stx2A), intimin (eaeA), flagellin (fliC), sigmaS--general stress sigma factor (rpoS) and iron superoxide dismutase (sodB) in E. coli O157:H7. Results indicate that reducing the storage temperature from 15 degrees C to 4 degrees C significantly (P<0.05) reduced the growth of Escherichia coli O157:H7 on Romaine lettuce, however, viable populations remained after the end of both storage periods. At end of the storage period, a 0.430 and 0.180 log decrease in E. coli O157:H7 was observed at 4 degrees C and 15 degrees C, respectively. Under both storage temperatures, total aerobic plate counts increased over the duration of the experiment. An increase in E. coli O157:H7 fold expression was observed with stx2A. Although stx1A exhibited upregulation for all storage conditions, variable gene expression was observed throughout the storage period. In addition, fliC was up-regulated during storage at 15 degrees C, while transcription at 4 degrees C storage changed only slightly. Expression of eaeA was variable at 15 degrees C with a tendency towards down-regulation, however, this gene was slightly up-regulated when stored at 4 degrees C. A slight upregulation of rpoS and sodB was also observed at 4 degrees C. In conclusion, our results suggest E. coli O157:H7 may become more virulent with prolonged storage of Romaine lettuce, particularly when

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

    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)

  17. Uniconazole-induced starch accumulation in the bioenergy crop duckweed (Landoltia punctata) II: transcriptome alterations of pathways involved in carbohydrate metabolism and endogenous hormone crosstalk

    Liu, Yang; Fang, Yang; Huang, Mengjun; Jin, Yanling; Sun, Jiaolong; TAO, XIANG; Zhang, Guohua; He, Kaize; Zhao, Yun; Zhao, Hai

    2015-01-01

    Background Landoltia punctata is a widely distributed duckweed species with great potential to accumulate enormous amounts of starch for bioethanol production. We found that L. punctata can accumulate starch rapidly accompanied by alterations in endogenous hormone levels after uniconazole application, but the relationship between endogenous hormones and starch accumulation is still unclear. Results After spraying fronds with 800 mg/L uniconazole, L. punctata can accumulate starch quickly, wit...

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

    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.

  19. Effect of CO2 levels on nutrient content of lettuce and radish

    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.

  20. Effect of CO_2 levels on nutrient content of lettuce and radish

    McKeehen, J. D.; Smart, D. J.; Mackowiak, C. L.; Wheeler, R. M.; Nielsen, S. S.

    Atmospheric carbon-dioxide enrichment is known to affect the yield of lettuce and radish grown in controlled environments, but little is known about CO_2 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 CO_2 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 CO_2 enrichment. The ash content of radish roots and of radish and lettuce leaves decreased with increasing levels of CO_2 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 roots 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 CO_2 level.

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

    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

  2. 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

    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 γ-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

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

    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.

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

    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

  5. Toxicity of polyfluorinated and perfluorinated compounds to lettuce (Lactuca sativa) and green algae (Pseudokirchneriella subcapitata).

    Ding, Guanghui; Wouterse, Marja; Baerselman, Rob; Peijnenburg, Willie J G M

    2012-01-01

    Recently, polyfluorinated and perfluorinated compounds (PFCs) have been detected in most surface waters around the world. Because some PFCs are persistent and tend to accumulate in surface waters, their potential adverse effects to aquatic organisms have received increasing attention. Nevertheless, currently available toxicity information is limited. The aim of this study was to evaluate the toxicity effects of seven PFCs on root elongation of lettuce (Lactuca sativa) and photosynthesis of green algae (Pseudokirchneriella subcapitata). It was found that the toxicity profiles of both species tested were similar and had good relations with the fluorinated carbon-chain length of the PFCs investigated. One of the compounds tested, perfluorobutanoic acid, was found to be more toxic than expected in the algae test, which may be related with acidification of the test solution. It was concluded that because short-chained PFCs are becoming the predominant PFC pollutants in surface waters, their long-term toxicity and mixture toxicity with other PFCs should be studied in greater detail. PMID:21626016

  6. Transfer of Metals in Food Chain: An Example with Copper and Lettuce

    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.

  7. SURVEY OF BIOLOGICAL HAZARDS IN THE LETTUCE USED IN COMMERCIAL SNACKS (SANDWICHES) FROM CURITIBA, PR, BRAZIL

    Mogharbel, Assuan Djamila Ibrahim; Felipe Richter REIS; Masson, Maria Lucia, 1958-

    2009-01-01

    Over the last decades, lettuce has been associated to several foodborne outbreaks. The present study surveyed the microbiological and parasitological contamination of green leaf lettuce used in sandwiches sold in snack bars in Curitiba, Paraná, Brazil. Lettuce was collected before and after commercial washing. Such procedure was made by holding and rotating the whole...

  8. SURVEY OF BIOLOGICAL HAZARDS IN THE LETTUCE USED IN COMMERCIAL SNACKS (SANDWICHES) FROM CURITIBA, PR, BRAZIL

    ASSUAN DJAMILA IBRAHIM MOGHARBEL; FELIPE RICHTER REIS; MARIA LUCIA MASSON

    2009-01-01

    Over the last decades, lettuce has been associated to several foodborne outbreaks. The present study surveyed the microbiological and parasitological contamination of green leaf lettuce used in sandwiches sold in snack bars in Curitiba, Paraná, Brazil. Lettuce was collected before and after commercial washing. Such procedure was made by holding and rotating the whol...

  9. Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg

    Jackson Marcondes

    2008-12-01

    Full Text Available 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 with Agrobacterium tumefaciens harboring the recombinant plasmid. It is the first description of a lettuce Brazilian variety "Vitória de Verão" genetically modified.

  10. Expression of 9-cis-EPOXYCAROTENOID DIOXYGENASE4 is essential for thermoinhibition of lettuce seed germination but not for seed development or stress tolerance.

    Huo, Heqiang; Dahal, Peetambar; Kunusoth, Keshavulu; McCallum, Claire M; Bradford, Kent J

    2013-03-01

    Thermoinhibition, or failure of seeds to germinate at warm temperatures, is common in lettuce (Lactuca sativa) cultivars. Using a recombinant inbred line population developed from a lettuce cultivar (Salinas) and thermotolerant Lactuca serriola accession UC96US23 (UC), we previously mapped a quantitative trait locus associated with thermoinhibition of germination to a genomic region containing a gene encoding a key regulated enzyme in abscisic acid (ABA) biosynthesis, 9-cis-EPOXYCAROTENOID DIOXYGENASE4 (NCED4). NCED4 from either Salinas or UC complements seeds of the Arabidopsis thaliana nced6-1 nced9-1 double mutant by restoring germination thermosensitivity, indicating that both NCED4 genes encode functional proteins. Transgenic expression of Salinas NCED4 in UC seeds resulted in thermoinhibition, whereas silencing of NCED4 in Salinas seeds led to loss of thermoinhibition. Mutations in NCED4 also alleviated thermoinhibition. NCED4 expression was elevated during late seed development but was not required for seed maturation. Heat but not water stress elevated NCED4 expression in leaves, while NCED2 and NCED3 exhibited the opposite responses. Silencing of NCED4 altered the expression of genes involved in ABA, gibberellin, and ethylene biosynthesis and signaling pathways. Together, these data demonstrate that NCED4 expression is required for thermoinhibition of lettuce seeds and that it may play additional roles in plant responses to elevated temperature. PMID:23503626

  11. Study on the Processing Technology of Edible Lettuce Paper%可食性生菜纸制备工艺研究

    王士奎; 王洪彩; 李文香; 孙树杰; 王丽娇

    2013-01-01

      为探究生菜纸最佳制备工艺,以结球生菜加工下脚料为原料,分别研究了打浆条件、黏结剂选配、干燥条件对生菜纸成型效果的影响。结果表明,生菜打浆加水量和最适时间分别为40%和75 s;复配黏结剂成型效果优于单一黏结剂,最适黏结剂复配为CMC-Na 0.4%、海藻酸钠0.4%、可溶性淀粉3%和黄原胶0.5%;热风干燥工艺条件为温度60℃,时间4 h,以上条件下制成的生菜纸含水量15%,色泽鲜艳,成纸性、易揭性良好。%  The optimum processing conditions for the preparation of lettuce paper based on iceberg lettuce processing residues, including beating, selecting adhesives, drying, were studied. Results showed that the best water added and beating time was 40%and 75 s. The effect of mixed adhesives was better than that of single adhesive for shaping, the optimum mixed adhesive addition amounts were CMC-Na0.4 %, alginate0.4 %, soluble starch3%, and xanthangum0.5%, which could get the best sharp and flavor. Besides, the mixtures were dried by hot air with temperature being of 60℃, the dehydration time was 4 hours, and the end figuration moisture of lettuce paper was 15%, respectively. Under this condition, the achieved lettuce paper had bright colors, good paper properties, stripping.

  12. Uptake of 8:2 perfluoroalkyl phosphate diester and its degradation products by carrot and lettuce from compost-amended soil.

    Bizkarguenaga, E; Zabaleta, I; Prieto, A; Fernández, L A; Zuloaga, O

    2016-06-01

    The present work studied the uptake of 8:2 perfluoroalkyl phosphate diester (diPAP) by two different crops (lettuce and carrot) and two different amended soils. Firstly, the possible degradation of 8:2 diPAP in the absence of crop was studied and 8:2 monoPAP (monophosphate), 8:2 FTCA (saturated fluorotelomer carboxylate), 8:2 FTUCA (unsaturated fluorotelomer carboxylate), 7:3 FTCA (saturated fluorotelomer carboxylate), PFHpA (perfluoroheptanoic acid), PFHxA (perfluorohexanoic acid) and PFOA (perfluorooctanoic acid) were detected. In the presence of crops, different degradation products were detected in the soil and, while PFNA (perfluorononanoic acid), PFHpA, PFHxA, PFPeA (perfluoropentacoic acid), PFBA (perfluorobutanoic acid), 7:3 FTCA and PFOA were determined in the cultivation media when carrot was grown, PFOA was the only degradation product detected in the case of lettuce experiments. Regarding the uptake in carrot, all the degradation products except 7:3 FTCA were translocated from the soil to the carrot. Carrot core, peel and leaves bioconcentration factors, BCFs, were determined for 8:2 diPAP and its degradation products. Values lower than method detection limits for core and low BCFs in peel (0.025-0.042) and leaves (0.028-0.049) were achieved for 8:2 diPAP. Regarding to the degradation products, the higher their water solubility, the higher the plant translocation. In this sense, the lower the carbon chain length of PFCAs, the higher the BCFs determined (PFBA > PFHxA > PFHpA > PFOA > PFNA). In general, lower total BCFs were achieved when the total organic carbon of the soils increased. For lettuce experiments, 8:2 diPAP (0.04-0.18) and PFOA (0.28-1.57) were only determined in lettuce heart. PMID:26991379

  13. An improved method for transformation of lettuce by Agrobacterium tumefaciens with a gene that confers freezing resistance

    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.

  14. Evaluation of the phytotoxicity of polycontaminated industrial effluents using the lettuce plant (Lactuca sativa) as a bioindicator.

    Charles, Jérémie; Sancey, Bertrand; Morin-Crini, Nadia; Badot, Pierre-Marie; Degiorgi, François; Trunfio, Giuseppe; Crini, Grégorio

    2011-10-01

    Industrial wastewater containing heavy metals is generally decontaminated by physicochemical treatment consisting in insolublizing the contaminants and separating the two phases, water and sludge, by a physical process (filtration, settling or flotation). However, chemical precipitation does not usually remove the whole pollution load and the effluent discharged into the environment can be toxic even if it comes up to regulatory standards. To assess the impact of industrial effluent from 4 different surface treatment companies, we performed standardized bioassays using seeds of the lettuce Lactuca sativa. We measured the rate of germination, and the length and mass of the lettuce plantlet. The results were used to compare the overall toxicity of the different effluents: effluents containing copper and nickel had a much higher impact than those containing zinc or aluminum. In addition, germination tests conducted using synthetic solutions confirmed that mixtures of metals have higher toxicity than the sum of their separate constituents. These biological tests are cheap, easy to implement, reproducible and highlight the effects caused by effluent treated with the methods commonly applied in industry today. They could be routinely used to check the impact of industrial discharges, even when they meet regulatory requirements for the individual metals. PMID:21835466

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

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

    2004-01-01

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

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

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

    2012-01-01

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

  17. Searching the best equilibrium moisture equation for lettuce seeds using measures of curvature and bias

    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.

  18. Lettuce genotype resistance to "soft rot" caused by Pectobacterium carotovorum subsp. carotovorum

    Kátia Cilene da Silva Felix; Willams José de Oliveira; Rosa de Lima Ramos Mariano; Elineide Barbosa de Souza

    2014-01-01

    Soft rot, caused by Pectobacterium carotovorum subsp. carotovorum (Pcc), is the main bacterial disease affecting lettuce (Lactuca sativa L.) crops in Brazil and leads to significant yield losses. This study aimed to assess the reaction of lettuce genotypes to soft rot induced by a virulent isolate and the stability of the resistance to three isolates varying in virulence. Using a descriptive ordinal scale ranging from 1 to 9 a classification system was defined: class 1 = resistant (R): severi...

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

    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.

  20. Root growth and soil nitrogen depletion by onion, lettuce, early cabbage and carrot

    Thorup-Kristensen, K

    2001-01-01

    Experiments examining root growth, the utilization of N and the effect of green manures were carried out on four vegetable crops. Large differences were observed both in rooting depth penetration rates, and in final rooting depth and distribution. Onion had a very low depth penetration rate, carrot an intermediate rate, and lettuce and cabbage showed high rates. A combination of depth penetration rates and duration of growth determined rooting depth at harvest. Therefore, lettuce, which had a...

  1. Transfer of Metals in Food Chain: An Example with Copper and Lettuce

    Vincevica-Gaile, Z; M. Klavins

    2012-01-01

    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...

  2. Impact of Biofield Treatment on Growth and Yieldof Lettuce and Tomato

    Trivedi, Mahendra

    2012-01-01

    Recent studies report the effect of biofield treatment on changes in structural characteristics of organic and inorganic matter, on cancer cells in vitro and on overall plant development. This study tested the impact of the same treatment applied to lettuce and tomato seeds and transplants (Lactuca sativa var. capitata and Lycopersiconesculentum var. Roma) in commercial plantings with and without fertilizers and pesticides, in relation to yield, quality, and pest inhibition. Treated lettuce p...

  3. Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg

    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...

  4. Effect of short-wavelength light on lettuce growth and nutritional quality

    Urbonavičiūtė, Akvilė; Pinho, Paulo; Samuolienė, Giedrė; Duchovskis, Pavelas; Vitta, Pranciškus; Stonkus, Audrius; Tamulaitis, Gintautas; Žukauskas, Artūras; Halonen, Liisa

    2007-01-01

    Influence of short-wavelength light on growth, development and nutritional quality of lettuce was studied by growing lettuce Lactuca sativa L. cv. ‘Grand rapids’ in phytotron under LED-based illumination with bicomponent spectrum consisting of red component (640 nm) and short-wavelength component in cyan (500 nm), blue (460 nm), or near-UV (365 nm) regions. Biometric characteristics and concentrations of pigments and sugars were measured 39 days after germination. Drastic sensitivity of total...

  5. Effect of Plant Age and Longidorus africanus on the Growth of Lettuce and Carrot

    Huang, Xiang; Ploeg, Antoon T.

    2001-01-01

    Needle nematodes, Longidorus africanus, were added to carrot and lettuce seedlings in a range of inoculum levels and at various times after seeding. The effects of inoculum density and delayed inoculation on plant growth were analyzed according to Seinhorst's damage function. Growth of both lettuce and carrot was severely affected by L. africanus, but delaying nematode inoculation until 10 days after seeding significantly increased estimated minimum yields in both crop species. Tolerance leve...

  6. Production and photosynthetic activity of Mimosa Verde and Mimosa Roxa lettuce in two farming systems

    Aline Mabel Rosa; Hizumi Lua Sarti Seó; Maila Berté Volpato; Nathalie Vieira Foz; Tatiane Carine da Silva; Jorge Luiz Barcelos Oliveira; Rosete Pescador; Juliana Bernardi Ogliari

    2014-01-01

    Lettuce (Lactuca sativa L.) is the most commonly consumed leaf vegetable in the Brazilian diet, and it is a good source of vitamins and minerals. It is widely grown in the conventional farming system. However, the hydroponic farming system has been gaining importance in the market, wining confidence from consumers, who are becoming increasingly more demanding on food quality. The objective of this study was to evaluate the performance of two lettuce cultivars on hydroponic and conventional fa...

  7. Quorum Sensing Activity of Enterobacter asburiae Isolated from Lettuce Leaves

    Kok-Gan Chan

    2013-10-01

    Full Text Available Bacterial communication or quorum sensing (QS is achieved via sensing of QS signaling molecules consisting of oligopeptides in Gram-positive bacteria and N-acyl homoserine lactones (AHL in most Gram-negative bacteria. In this study, Enterobacteriaceae isolates from Batavia lettuce were screened for AHL production. Enterobacter asburiae, identified by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS was found to produce short chain AHLs. High resolution triple quadrupole liquid chromatography mass spectrometry (LC/MS analysis of the E. asburiae spent supernatant confirmed the production of N-butanoyl homoserine lactone (C4-HSL and N–hexanoyl homoserine lactone (C6-HSL. To the best of our knowledge, this is the first report of AHL production by E. asburiae.

  8. EFFECTS OF TRICHODERMA HARZIANUM ON LETTUCE IN PROTECTED CULTIVATION

    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.

  9. Characterization of a cadmium-zinc complex in lettuce leaves.

    McKenna, I M; Chaney, R L

    1995-04-01

    Vegetable food contributes a higher amount of daily cadmium (Cd) intake in humans than food of animal origin. The bioavailability of plant Cd depends on the content of plant zinc (Zn). The mechanism by which increased plant Zn lowers the intestinal absorption of plant Cd could be mediated by changes in the chemical speciation of Cd or Zn in plant edible tissues, including Zn-induced phytochelatin synthesis. To test this hypothesis we investigated the chemical speciation of Cd and Zn in leaf extracts of lettuce grown under 10 microM of Cd accompanied by 0.32 or 31.6 microM Zn in nutrient solution. Gel filtration chromatography of the low- or high-Zn leaf extracts yielded a major low molecular weight Cd-Zn complex that eluted at similar elution volume. Compared to low-Zn leaf extracts, high-Zn leaf extracts contained a higher proportion of Zn incorporated into high molecular weight components, and higher content of the amino acids Cys, Gly, Gly, and Asp in the low molecular weight Cd-Zn complex. The peptides isolated by high performance liquid chromatography (HPLC) of the Cd-Zn complex from the low- or high-Zn leaf extracts did not have an amino acid composition identical to phytochelatins. We concluded that 1. Sequestration of Cd or Zn via phytochelatin does not occur in leaves of lettuce containing levels of those metals representatives of Zn-Cd or Cd-only contaminated crops; and 2. Higher Cys, Glu, Gly, and Asp content in high-Zn than low-Zn leaves could lower Cd absorption in animals fed high-Zn crop diets, by enhancing metallothionein synthesis or changing Cd or Zn speciation in the animal gut. PMID:7626369

  10. Survival of enteric pathogens during butterhead lettuce growth: crop stage, leaf age, and irrigation.

    Van der Linden, Inge; Cottyn, Bart; Uyttendaele, Mieke; Vlaemynck, Geertrui; Heyndrickx, Marc; Maes, Martine

    2013-06-01

    The survival of Salmonella enterica serovar Thompson and Escherichia coli O157 was investigated on growing butterhead lettuce plants in the plant-growth chamber and greenhouse. All inoculation tests were made under conditions that approximate the greenhouse conditions for butterhead lettuce cultivation in Flanders (Belgium). The survival and proliferation of the pathogens on the leaves was determined at days 0, 4, and 8 after inoculation using standard plating techniques on selective medium. In the growth chamber, the extent to which both pathogens were able to multiply on the lettuce leaves was influenced by crop stage and leaf age. On young plants, the older leaves supported pathogen survival better. On nearly mature plants, pathogen population sizes were significantly higher on the old and young leaves compared with middle-aged leaves (plettuce was enhanced by overhead irrigation. The moist conditions between the folded inner leaves are likely contributing to the survival of enteric pathogens in the lettuce head. Butterhead lettuce grown in greenhouses with a sprinkle irrigation system may present a potential health hazard when contaminated near harvest. Experimental design (growth chamber versus greenhouse) largely influences enteric pathogen behavior on growing lettuce plants. PMID:23614801

  11. Freshly characterization and storability of mini head lettuces at optimal and abusive temperatures.

    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

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

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

    2016-01-01

    This study assessed the contamination of Escherichia coli, in lettuce grown with treated domestic wastewater in four different irrigation configurations: open spray, spray under plastic sheet cover, open drip and drip under plastic sheet cover. Samples of lettuce from each irrigation configuration and irrigating wastewater were collected during the growing season. No E. coli was detected in lettuce from drip irrigated beds. All lettuce samples from spray beds were positive for E. coli, however, no statistical difference (p > 0.05) was detected between lettuces grown in open spray or covered spray beds. The results from the field experiment were also compared to a laboratory experiment which used submersion of lettuce in wastewater of known E. coli concentration as a surrogate method to assess contamination following irrigation. The microbial quality of spray bed lettuces was not significantly different from submersed lettuce when irrigated with wastewater containing 1,299.7 E. coli MPN/100 mL (p > 0.05). This study is significant since it is the first to validate that the microbial contamination of lettuce irrigated with wastewater in the field is comparable with a laboratory technique frequently applied in the quantitative microbial risk assessment of the consumption of wastewater irrigated salad crops. PMID:27508380

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

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

    2016-01-01

    Lettuce drop, caused by the soil borne pathogen Sclerotinia sclerotiorum, is one of the most common and serious diseases of lettuce worldwide. Increased concerns about the side effects of chemical pesticides have resulted in greater interest in developing biocontrol strategies against S. sclerotiorum. However, relatively little is known about the mechanisms of Streptomyces spp. as biological control agents against S. sclerotiorum on lettuce. Two Streptomyces isolates, S. exfoliatus FT05W and S. cyaneus ZEA17I, inhibit mycelial growth of Sclerotinia sclerotiorum by more than 75% in vitro. We evaluated their biocontrol activity against S. sclerotiorum in vivo, and compared them to Streptomyces lydicus WYEC 108, isolated from Actinovate®. When Streptomyces spp. (10(6) CFU/mL) were applied to S. sclerotiorum inoculated substrate in a growth chamber 1 week prior lettuce sowing, they significantly reduced the risk of lettuce drop disease, compared to the inoculated control. Interestingly, under field conditions, S. exfoliatus FT05W and S. cyaneus ZEA17I protected lettuce from drop by 40 and 10% respectively, whereas S. lydicus WYEC 108 did not show any protection. We further labeled S. exfoliatus FT05W and S. cyaneus ZEA17I with the enhanced GFP (EGFP) marker to investigate their rhizosphere competence and ability to colonize lettuce roots using confocal laser scanning microscopy (CLSM). The abundant colonization of young lettuce seedlings by both strains demonstrated Streptomyces' capability to interact with the host from early stages of seed germination and root development. Moreover, the two strains were detected also on 2-week-old roots, indicating their potential of long-term interactions with lettuce. Additionally, scanning electron microscopy (SEM) observations showed EGFP-S. exfoliatus FT05W endophytic colonization of lettuce root cortex tissues. Finally, we determined its viability and persistence in the rhizosphere and endorhiza up to 3 weeks by quantifying

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

    Xiaoyulong eChen

    2016-05-01

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

  15. ANALISIS PENGARUH VARIASI PERSENTASE RAGI (Saccharomyces cerevisiae DAN WAKTU PADA PROSES FERMENTASI DALAM PEMANFAATAN DUCKWEED (Lemna minor SEBAGAI BIOETANOL

    Siti Khodijah

    2015-04-01

    Full Text Available Salah satu alternatif dalam mendukung ketersediaan sumber daya energi terbarukan adalah dengan memanfaatkan sumber dari non fosil seperti bioetanol. Bioetanol merupakan etanol yang dibuat dari biomass yang mengandung komponen pati (karbohidrat atau selulosa yang selanjutnya di fermentasi menggunakan bantuan mikroorganisme (Sacharomyces cerevisiae. Karbohidrat yang digunakan pada penelitian ini berasal dari Lemna minor (Duckweed. Penelitian ini bertujuan membuat bioetanol dari Lemna minor dengan variasi penambahan ragi dan lamanya waktu fermentasi terhadap nilai kadar etanol dan nilai densitas, serta mengetahui hubungan densitas dengan kadar etanol. Produksi bioetanol dari tanaman yang mengandung pati (karbohidrat, dilakukan melalui proses konversi karbohidrat menjadi gula (glukosa dengan hidrolisis asam (HCl, hidrolisat yang diperoleh selanjutnya dilakukan fermentasi dengan menambahkan yeast atau ragi sehingga diperoleh bioetanol. Variabel yang digunakan adalah perubahan massa ragi 5%,15%, dan 25% serta lama fermentasi 5, 6, dan 7 hari . Hasil penelitian menunjukkan lama fermentasi dan persentase ragi mempengaruhi kadar etanol. Nilai kadar etanol optimum diperoleh presentase ragi 25% dengan lama fermentasi 7 hari sebesar 3.81% dengan density optimum sebesar 0.9438 gr/cm3, Hubungan nilai densitas berbanding terbalik dengan peningkatan kadar etanol.

  16. Impacts of UV radiation and photomodification on the toxicity of PAHs to the higher plant Lemna gibba (duckweed)

    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 π-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

  17. Development and phytochemical characterization of high polyphenol red lettuce with anti-diabetic properties.

    Cheng, Diana M; Pogrebnyak, Natalia; Kuhn, Peter; Krueger, Christian G; Johnson, William D; Raskin, Ilya

    2014-01-01

    Polyphenol-rich Rutgers Scarlet Lettuce (RSL) (Lactuca sativa L.) was developed through somaclonal variation and selection in tissue culture. RSL may contain among the highest reported contents of polyphenols and antioxidants in the category of common fruits and vegetables (95.6 mg/g dry weight and 8.7 mg/g fresh weight gallic acid equivalents and 2721 µmol/g dry weight and 223 µmol/g fresh weight Trolox equivalents). Three main compounds accumulate at particularly high levels in RSL: chlorogenic acid, up to 27.6 mg/g dry weight, cyanidin malonyl-glucoside, up to 20.5 mg/g dry weight, and quercetin malonyl-glucoside, up to 35.7 mg/g dry weight. Major polyphenolic constituents of RSL have been associated with health promotion as well as anti-diabetic and/or anti-inflammatory activities. Daily oral administration of RSL (100 or 300 mg/kg) for up to eight days acutely reduced hyperglycemia and improved insulin sensitivity in high fat diet-induced obese hyperglycemic mice compared to vehicle (water) control. Data presented here support possible use of RSL as a functional food for the dietary management of diabetes. PMID:24637790

  18. Development and phytochemical characterization of high polyphenol red lettuce with anti-diabetic properties.

    Diana M Cheng

    Full Text Available Polyphenol-rich Rutgers Scarlet Lettuce (RSL (Lactuca sativa L. was developed through somaclonal variation and selection in tissue culture. RSL may contain among the highest reported contents of polyphenols and antioxidants in the category of common fruits and vegetables (95.6 mg/g dry weight and 8.7 mg/g fresh weight gallic acid equivalents and 2721 µmol/g dry weight and 223 µmol/g fresh weight Trolox equivalents. Three main compounds accumulate at particularly high levels in RSL: chlorogenic acid, up to 27.6 mg/g dry weight, cyanidin malonyl-glucoside, up to 20.5 mg/g dry weight, and quercetin malonyl-glucoside, up to 35.7 mg/g dry weight. Major polyphenolic constituents of RSL have been associated with health promotion as well as anti-diabetic and/or anti-inflammatory activities. Daily oral administration of RSL (100 or 300 mg/kg for up to eight days acutely reduced hyperglycemia and improved insulin sensitivity in high fat diet-induced obese hyperglycemic mice compared to vehicle (water control. Data presented here support possible use of RSL as a functional food for the dietary management of diabetes.

  19. Comparative Study of Lettuce and Radish Grown Under Red and Blue Light-Emitting Diodes (LEDs) and White Fluorescent Lamps

    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.

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

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

    2013-01-01

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

  1. Mudanças nas características físico-químicas de um latossolo vermelho-amarelo distrófico após a irrigação com água de reúso na cultura da alface-crespa (Lactuca sativa, L. Physical and chemical characteristics changes of a red-yellow latosol after implementation of water reuse in the culture of curly lettuce (Lactuca sativa, L.

    Antonio C. T. Varallo

    2012-04-01

    where were grown two rounds of curly lettuce (Lactuca sativa, L. with two treatments with three repetitions each: witness (provisioning water and reuse. The results did not show increases in some chemical attributes of fertility as iron, magnesium, zinc, boron, potassium, nitrate, sodium and calcium; decrease in organic matter and manganese, besides increase of hydraulic conductivity and the electrical conductivity of the soil. It was also observed a reduction of the soil pH, besides the increase of SAR and ESP. Thus it must be concluded the application of water reuse for agricultural purposes should be in a rational way, and the elevation of salts in the soil must be monitored.

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

    Jensen, Annette Nygaard; Storm, Christina; Baggesen, Dorte Lau;

    2011-01-01

    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) containing 16 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...

  3. Expression of dengue-3 premembrane and envelope polyprotein in lettuce chloroplasts.

    Kanagaraj, Anderson Paul; Verma, Dheeraj; Daniell, Henry

    2011-07-01

    Dengue is an acute febrile viral disease with >100 million infections occurring each year and more than half of the world population is at risk. Global resurgence of dengue in many urban centers of the tropics is a major concern. Therefore, development of a successful vaccine is urgently needed that is economical and provide long-lasting protection from dengue virus infections. In this manuscript, we report expression of dengue-3 serotype polyprotein (prM/E) consisting of part of capsid, complete premembrane (prM) and truncated envelope (E) protein in an edible crop lettuce. The dengue sequence was controlled by endogenous Lactuca sativa psbA regulatory elements. PCR and Southern blot analysis confirmed transgene integration into the lettuce chloroplast genome via homologous recombination at the trnI/trnA intergenic spacer region. Western blot analysis showed expression of polyprotein prM/E in different forms as monomers (~65 kDa) or possibly heterodimers (~130 kDa) or multimers. Multimers were solubilized into monomers using guanidine hydrochloride. Transplastomic lettuce plants expressing dengue prM/E vaccine antigens grew normally and transgenes were inherited in the T1 progeny without any segregation. Transmission electron microscopy showed the presence of virus-like particles of ~20 nm diameter in chloroplast extracts of transplastomic lettuce expressing prM/E proteins, but not in untransformed plants. The prM/E antigens expressed in lettuce chloroplasts should offer a potential source for investigating an oral Dengue vaccine. PMID:21431782

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

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

    2004-09-01

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

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

    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

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

    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

  7. 水葫芦发酵沼液对紫叶莴苣生长和品质的影响%Effects of Different Ratios of Biogas Slurry of Water Hyacinth (Eichhornia crassipes) Substitute Chemical Nitrogen Fertilizers on Growth and Quality of Lettuce (L.sativa)

    汪吉东; 马洪波; 高秀美; 许仙菊; 宁运旺; 张辉; 张永春

    2011-01-01

    Field experiment was conducted to explore the effects of different ratios of biogas slurry substitute chemical nitrogen fertilizers on yield, nutrient accumulation and fresh quality of lettuce (L. Sativa). The results showed that the application of fertilizers and slurry could promote the growth of lettuce. The yields of treatments with 50%, 75% and 100% ratios of slurry were 9.1%, 16.1% and 10.3% respectively higher than that of 100% urea treatment, but chemical fertilizer as the basal got a better effect than slurry while biogas slurry got better growth and higher nutrient absorption as the after manuring compared to chemical N fertilizer. The economic yield increased with the increasing ratio of slurry. Compared to 100% chemical treatment, nitrate contents under biogas slurry application ratio of 50%, 75% and 100% were decreased by 13.6%, 14.3% and 11.3%, respectively. However, soluble sugar, Vc contents and free amino acid concentrations of 100% biogas slurry application were lower but were highest of 75% biogas slurry application. In conclusion, the proportion of 75% slurry application was the best fertilizer ratio.%利用田间小区试验研究了等氮量下不同比例水葫芦发酵沼液对紫叶莴苣生长、产量、氮磷钾养分吸收量及茎部品质的影响.结果表明,沼液替代化肥氮比例为50%、75%和100%处理莴苣产量分别比100%化肥氮处理增加9.1%、16.1%和10.3%.但基肥中化肥的比例上升能促进莴苣苗期的生长和提高氮的吸收,而沼液作为追肥较单施化肥更能促进莴苣的生长和养分的吸收.同时沼液氮施用比例增加,莴苣商品化率提高.和100%化肥处理相比,沼液施用比例为50%、75%和100%处理硝酸盐含量分别降低了13.6%、14.3%和11.3%.沼液氮施用比例为50%~100%处理中,100%沼液氮施用处理其可溶性糖、Vc含量和游离氨基酸含量都最低,而75%沼液氮施用比例下可获得最高的氨基

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

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

  9. 76 FR 81468 - Notice of Decision to Authorize the Importation of Shredded Lettuce From Egypt Into the...

    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...

  10. Essential oils reduce Escherichia coli O157:H7 and Salmonella on iceberg and romaine lettuce without affecting produce quality

    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) ...

  11. Fifteen years of verticillium wilt of lettuce in america’s salad bowl: a tale of immigration, subjugation and abatement.

    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, ...

  12. Predicting lettuce canopy photosynthesis with statistical and neural network models

    Frick, J.; Precetti, C.; Mitchell, C. A.

    1998-01-01

    An artificial neural network (NN) and a statistical regression model were developed to predict canopy photosynthetic rates (Pn) for 'Waldman's Green' leaf lettuce (Latuca sativa L.). All data used to develop and test the models were collected for crop stands grown hydroponically and under controlled-environment conditions. In the NN and regression models, canopy Pn was predicted as a function of three independent variables: shootzone CO2 concentration (600 to 1500 micromoles mol-1), photosynthetic photon flux (PPF) (600 to 1100 micromoles m-2 s-1), and canopy age (10 to 20 days after planting). The models were used to determine the combinations of CO2 and PPF setpoints required each day to maintain maximum canopy Pn. The statistical model (a third-order polynomial) predicted Pn more accurately than the simple NN (a three-layer, fully connected net). Over an 11-day validation period, average percent difference between predicted and actual Pn was 12.3% and 24.6% for the statistical and NN models, respectively. Both models lost considerable accuracy when used to determine relatively long-range Pn predictions (> or = 6 days into the future).

  13. Carbon dioxide exchange of lettuce plants under hypobaric conditions

    Corey, K. A.; Bates, M. E.; Adams, S. L.; MacElroy, R. D. (Principal Investigator)

    1996-01-01

    Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m2, a total gas volume of about 0.7 m3, and a leak rate at 50 kPa of CO2 than at 81 Pa CO2. This is consistent with reports showing greater inhibition of photorespiration (Pr) in reduced O2 at low CO2 concentrations. When the partial pressure of O2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.

  14. Carbon dioxide exchange of lettuce plants under hypobaric conditions

    Corey, K. A.; Bates, M. E.; Adams, S. L.

    1996-01-01

    Growth of plants in a Controlled Ecological Life Support System (CELSS) may involve the use of hypobaric pressures enabling lower mass requirements for atmospheres and possible enhancement of crop productivity. A controlled environment plant growth chamber with hypobaric capability designed and built at Ames Research Center was used to determine if reduced pressures influence the rates of photosynthesis (Ps) and dark respiration (DR) of hydroponically grown lettuce plants. The chamber, referred to as a plant volatiles chamber (PVC), has a growing area of about 0.2 m^2, a total gas volume of about 0.7 m^3, and a leak rate at 50 kPa of photorespiration (Pr) in reduced O_2 at low CO_2 concentrations. When the partial pressure of O_2 was held constant but the total pressure was varied between 51 and 101 kPa, the rate of CO_2 uptake was nearly constant, suggesting that low pressure enhancement of Ps may be mainly attributable to lowered partial pressure of O_2 and the accompanying reduction in Pr. The effects of lowered partial pressure of O_2 on Ps and DR could result in substantial increases in the rates of biomass production, enabling rapid throughput of crops or allowing flexibility in the use of mass and energy resources for a CELSS.

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

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

  16. 沼液追肥对菇渣复合基质栽培生菜产量和品质的影响%Effect of biogas slurry on the yield and quality of lettuce in compound substrate with mushroom compost dregs cultivation

    夏亚真; 刘金; 李胜利; 孙治强

    2012-01-01

    为研究菇渣和沼液2种农业二次废弃物在蔬菜无土栽培中的配套应用技术,试验采用生菜为材料,以菇渣与草炭按体积比1∶1为栽培基质,研究了追施不同沼液浓度和追施方式对生菜产量和品质的影响.结果表明,追施适当浓度的沼液能够提高生菜的产量和品质,其中以叶面喷施沼液与水体积比为1∶4的处理效果最佳,其根际环境电导率较低且产量最高为6 607.39 kg·hm-3,Ve的含量为2 186.2 mg·kg-1比对照提高了20%且达到了显著水平,硝态氮含量为510.56 μg·g-1显著低于硝酸盐含量≤3 000 mg· kg-1的国家标准.%To study the two agricultural secondary wastes of biogas slurry and mushroom compost dregs in application technique for vegetable crops soilless cultivation, the effect of biogas slurry of different concentrations and different methods on the yield and quality of lettuce was studied through experiments of biogas slurry as supply application with water at different ratios. In the experiment, the mixture of mushroom compost dregs and turf was used as substrate of lettuce culture with the ratio of 1: 1. The result showed that the biogas slurry of appropriate concentration could increase the yield of lettuce, and improve the quality of lettuce. The optimal combination of biogas slurry at the volumetric ratio of biogas slurry and water was 1:4 for spraying on leaves of lettuce. The highest yield of lettuce was 6 607.39 kg · hm-3 when this treatment was used and the rhizosphere had lower specific conductivity. The higher content of Vc of lettuce was 2 186. 2 mg · kg-1, which was used and it was 20% higher than that of the control. The content of nitrate of lettuce was 510. 56μg · g-1, which was significantly lower than that the nitrate content standard of 3 000 mg · kg -1.

  17. The sensitivity of an hydroponic lettuce root elongation bioassay to metals, phenol and wastewaters.

    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 (48 h in this test versus 120 h 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 124 mg L(-1) and 108-180 mg L(-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

  18. Root exudation and root development of lettuce (Lactuca sativa L.cv. Tizian as affected by different soils

    GünterNeumann

    2014-01-01

    Full Text Available Development and activity of plant roots exhibits high adaptive variability. Although it is well-documented, that physicochemical soil properties can strongly influence root morphology and root exudation, particularly under field conditions, a comparative assessment is complicated by the impact of additional factors, such as climate and cropping history. To overcome these limitations, in this study, field soils originating from an unique experimental plot system with three different soil types, which were stored at the same field site for ten years and exposed to the same agricultural management practice, were used for an investigation on effects of soil type on root development and root exudation. Lettuce (Lactuca sativa L. cv. Tizian was used as a model plant, grown under controlled environmental conditions in a minirhizotrone system equipped with root observation windows (rhizoboxes. Root exudates were collected by placing sorption filters onto the root surface followed by subsequent extraction and GC-MS profiling of the trapped compounds. Surprisingly, even in absence of external stress factors with known impact on root exudation, such as pH extremes, water and nutrient limitations/toxicities or soil structure effects (use of sieved soils, root growth characteristics (root length, fine root development as well as profiles of root exudates were strongly influenced by the soil type used for plant cultivation. The results coincided well with differences in rhizosphere bacterial communities, detected in field-grown lettuce plants cultivated on the same soils (Schreiter et al., this issue. The findings suggest that the observed differences may be the result of plant interactions with the soil-specific microbiomes.

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

    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.

  20. Genetic and biochemical evaluation of natural rubber from Eastern Washington prickly lettuce (Lactuca serriola L.).

    Bell, Jared L; Burke, Ian C; Neff, Michael M

    2015-01-21

    Alternative sources of natural rubber are of importance due to economic, biological, and political threats that could diminish supplies of this resource. Prickly lettuce (Lactuca serriola L.) synthesizes long-chain natural rubber and was studied to determine underlying genetic and phenotypic characteristics of rubber biosynthesis. Genotypic and phenotypic analysis of an F2 segregating population using EST-SSR markers led to the discovery of genetic regions linked to natural rubber production. Interval mapping (IM) and multiple QTL mapping (MQM) identified several QTL in the mapping population that had significance based on LOD score thresholds. The discovered QTL and the corresponding local markers are genetic resources for understanding rubber biosynthesis in prickly lettuce and could be used in marker-assisted selection (MAS) breeding. Prickly lettuce is an excellent candidate for elucidating the rubber synthesis mechanism and has potential as a crop plant for rubber production. PMID:25513853

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

    Cheng-Wei Liu

    2014-04-01

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

  2. Science Letters: Transient expression of chicken alpha interferon gene in lettuce

    Li SONG; De-gang ZHAO; Yong-jun WU; Yi LI

    2008-01-01

    We investigated the possibility of producing chicken alpha interferon (ChIFN-α) in transgenic plants.The cDNA encoding ChIFN-a 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.Re-combinant protein exhibited antiviral activity in vitro by inhibition of vesicular stomatitis virus (VSV) replication on chicken embryonic fibroblast (CEF).The results demonstrate that biologically active avian cytokine with potential pharmaceutical ap-plications could be expressed in transgenic lettuce plants and that it is possible to generate interferon protein in forage plants for preventing infectious diseases of poultry.

  3. A New Image Segmentation Algorithm and It’s Application in lettuce object segmentation

    Xiaodong Zhang

    2012-07-01

    Full Text Available Lettuce image segmentation which based on computer image processing is the premise of non-destructive testing of lettuce quality. The traditional 2-D maximum entropy algorithm has some faults, such as low accuracy of segmentation, slow speed, and poor anti-noise ability. As a result, it leads to the problems of poor image segmentation and low efficiency. An improved 2-D maximum entropy algorithm is presented in this paper. It redistricts segmented regions and furtherly classifies the segmented image pixels with the method of the minimum fuzzy entropy, and reduces the impact of noise points, as a result the image segmentation accuracy is improved. The improved algorithm is used to lettuce object segmentation, and the experimental results show that the improved segmentation algorithm has many advantages compared with the traditional 2-D maximum entropy algorithm, such as less false interference, strong anti-noise ability, good robustness and validity.  

  4. The Development of Lettuce Cake%莴苣蛋糕的研制

    李凡玥; 魏可鹏

    2015-01-01

    Peel and slice lettuce,hot very hot after beating the juice.Whip the blister,like eggs and lettuce juice with sugar etc.Stir in flour and injection molding ,then baking products.Be determined the time of whip the eggs by single factor experiment egg for 10 min,for the amount of lettuce juice 50 g,cake quality is better.With the added quantity of flour,lettuce juice,sugar,blend oil for factors,through the four factors three levels orthogonal experiment determining the optimal lettuce cake recipe for flour 60 g, lettuce juice 50 g,sugar 80 g,and blend oil 20 mL.%莴苣去皮切片,热烫打浆后制汁,鸡蛋、莴苣汁加糖等搅打起泡,加入面粉拌匀,注模,烘烤得成品。由单因素实验确定打蛋时间10 min,莴苣汁加入量50 g蛋糕质量较好。以面粉、莴苣汁、白砂糖、调和油的用量为因素,通过三水平四因素正交试验确定莴苣蛋糕制作的最优配方为面粉60 g、莴苣汁50 g、白砂糖80 g、调和油20 mL。

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

    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

  6. Binding of Virus-Like Particles of Norwalk Virus to Romaine Lettuce Veins▿

    Gandhi, Kamal M.; Mandrell, Robert E.; Tian, Peng

    2010-01-01

    Noroviruses (NoV) annually cause millions of cases of gastrointestinal disease in the United States. NoV are associated with raw shellfish outbreaks, particularly oysters, which are thought to bioaccumulate NoV particles during the filter-feeding process. NoV outbreaks, however, have also been known to occur from other common-source food-borne vehicles, such as lettuce, frozen raspberries, and salad. In this study, we evaluated romaine lettuce as a potential vehicle for NoV transmission by te...

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

    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.

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

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

    2016-09-01

    A potyvirus causing necrosis and leaf distortion on lettuce was found in the Lazio region of Italy. Host range analysis showed its ability to infect only Chenopodium quinoa and C. amaranticolor in addition to some lettuce cultivars. The virus could be transmitted by aphids of the species Myzus persicae. The complete 9829-nt genome was characterized. BLAST analysis of sequence of the complete encoded polyprotein showed that the most closely related virus is asparagus virus 1, with 52 % amino acid sequence identity. These results suggest that this virus should be considered a member of a new species in the genus Potyvirus. PMID:27287434

  9. Induction of viable but nonculturable Escherichia coli O157:H7 in the phyllosphere of lettuce: a food safety risk factor.

    Dinu, Laura-Dorina; Bach, Susan

    2011-12-01

    Escherichia coli O157:H7 continues to be an important human pathogen and has been increasingly linked to food-borne illness associated with fresh produce, particularly leafy greens. The aim of this work was to investigate the fate of E. coli O157:H7 on the phyllosphere of lettuce under low temperature and to evaluate the potential hazard of viable but nonculturable (VBNC) cells induced under such stressful conditions. First, we studied the survival of six bacterial strains following prolonged storage in water at low temperature (4°C) and selected two strains with different nonculturable responses for the construction of E. coli O157:H7 Tn7gfp transformants in order to quantitatively assess the occurrence of human pathogens on the plant surface. Under a suboptimal growth temperature (16°C), both E. coli O157:H7 strains maintained culturability on lettuce leaves, but under more stressful conditions (8°C), the bacterial populations evolved toward the VBNC state. The strain-dependent nonculturable response was more evident in the experiments with different inoculum doses (10(9) and 10(6) E. coli O157:H7 bacteria per g of leaf) when strain BRMSID 188 lost culturability after 15 days and strain ATCC 43895 lost culturability within 7 days, regardless of the inoculum dose. However, the number of cells entering the VBNC state in high-cell-density inoculum (approximately 55%) was lower than in low-cell-density inoculum (approximately 70%). We recorded the presence of verotoxin for 3 days in samples that contained a VBNC population of 4 to 5 log(10) cells but did not detect culturable cells. These findings indicate that E. coli O157:H7 VBNC cells are induced on lettuce plants, and this may have implications regarding food safety. PMID:21965401

  10. Influence of Extracellular Cellulose and Colanic Acid Production on the Survival of Shiga Toxin-Producing Escherichia coli on Spinach and Lettuce after Chlorine Treatment.

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

    2016-04-01

    Shiga toxin-producing Escherichia coli (STEC) strains produce extracellular cellulose and colanic acid, which may influence stress tolerance. This study investigates the role of these extracellular polymers on the tolerance of STEC to chlorine treatment after attachment to lettuce and spinach. Four STEC strains, two wild-type cellulose-producing and their cellulosedeficient derivatives, were used. One strain pair produced colanic acid in addition to cellulose. Spinach and lettuce with attached cells were treated with chlorinated water (50 and 150 ppm of free chlorine). The production of the extracellular polymers by the planktonic cells had small, but significant, effects on the survival of the attached pathogen when subjected to chlorine treatment. On the lettuce surface, the colanic acid-producing, cellulose-negative mutant (49d) was most susceptible to the treatment, declining significantly (P population by 0.9 and 1.4 log units after treatment with 50 and 150 ppm of chlorine, respectively. Chlorine treatment reduced populations of cellulose-deficient cells on the intact spinach surface 1.2 log units more than the wild type when treated with 150 ppm of chlorine (P populations of cellulose-producing cells were reduced by 1.5 log units more than their mutant counterparts when the cells also produced colanic acid (P < 0.05). A greater proportion of cells attached to the spinach leaf edge were injured by chlorine treatment compared with attached to the leaf surface. These results indicate that extracellular polymers do not generally increase the ability of STEC to survive chlorine treatment and that any effects on survival are influenced by location of attachment, type of leafy green, and concentration of chlorine. PMID:27052873

  11. Study of atmospheric tritium transfers in lettuce: kinetic study, equilibrium and organic incorporation during a continuous atmospheric exposure

    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)

  12. Tolerance of wheat and lettuce plants grown on human mineralized waste to high temperature stress

    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 °С) under different PAR intensities for 4 h. The status of the photosynthetic apparatus of the plants was assessed by external СО2 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.

  13. The analysis of the biomass and starch content of duckweed growing in swine wastewater%猪场污水中浮萍生物量和淀粉含量变化研究

    赵昭; 姚广保; 张艺琼; 赵云

    2012-01-01

    以四川常见的青萍(Lemna minor)、少根紫萍(Spirodela olygorrhiza)、稀脉浮萍(L.perpusilla)和紫萍(S.polyrrhiza)为研究对象,研究了猪场污水浓度和接种量对其生物产量和淀粉含量的影响.结果表明在5%的猪场污水中,浮萍科的4个种都有较高的生长速率.在35.4 g/m2的接种量时,青萍的淀粉含量最高可以达到干重的32.9%;在17.7 g/m2的接种量时,少根紫萍、稀脉浮萍和紫萍的最高淀粉含量分别可达到干重的44.4%、38.o%和35.5%.在单位时间内,紫萍具有更大的生物产量,每公顷每年的产量(鲜重)89.7t,但淀粉含量偏低.经综合研究比较,在四川地区气候条件下,少根紫萍能够制造更多淀粉,每公顷每年大约能生产淀粉11.4t,适宜作为能源植物推广.%The biomass and starch content of duckweed Lemna minor, Spirodela olygorrhiza , L. per-pusilla and S. polyrrhiza, collected from Chengdu in Sichuan. were investigated when they were cultured in swine wastewater. The results showed the common duckweed could grow fast in the 5 % swine waste water. At an optimal initial inoculum size of 35. 4 g/m2, the maximum starch content of Lemna minor was 32. 9% on a dry weight basis. At an optimal initial inoculum size of 17. 7g/m2. the highest starch content of S. olygorrhiza, L. perpusilla and S. polyrrhiza was 44. 4% ,38. 0% and 35. 5% on a dry weight basis, respectively. In the climate condition of Chengdu, S. polyrrhiza could produce the most biomass and S. olygorrhiza could produce the most starch. S. polyrrhiza could produce 89. 7 tons biomass(fresh weight) per hectare per year. S. olygorrhiza could produce 11. 4 tons starch per hectare per year and would be able to be a new energy plant widely used.

  14. High-Throughput Sequencing of Three Lemnoideae (Duckweeds) Chloroplast Genomes from Total DNA

    Wang, Wenqin; Messing, Joachim

    2011-01-01

    Background Chloroplast genomes provide a wealth of information for evolutionary and population genetic studies. Chloroplasts play a particularly important role in the adaption for aquatic plants because they float on water and their major surface is exposed continuously to sunlight. The subfamily of Lemnoideae represents such a collection of aquatic species that because of photosynthesis represents one of the fastest growing plant species on earth. Methods We sequenced the chloroplast genomes...

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

    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.

  16. Effects of different nutrients solutions on nutrients concentration and some qualitative traits of lettuce in hydroponics system

    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.

  17. Estimation of water turnover rates of captive West Indian manatees (Trichechus manatus) held in fresh and salt water

    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.

  18. A high-density, integrated genetic linkage map of lettuce (Lactuca spp.)

    Truco, M.J.; Antonise, R.; Lavelle, D.; Ochoa, O.; Kozik, A.; Witsenboer, H.; Fort, S.B.; Jeuken, M.J.W.; Kesseli, R.V.; Lindhout, P.; Michelmore, R.; Peleman, J.

    2007-01-01

    An integrated map for lettuce comprising of 2,744 markers was developed from seven intra- and inter-specific mapping populations. A total of 560 markers that segregated in two or more populations were used to align the individual maps. 2,073 AFLP, 152 RFLP, 130 SSR, and 360 RAPD as well as 29 other

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

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

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

    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 ...

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

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

  2. Breeding and genetics of lettuce against race 2 of Verticillium wilt

    Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is a destructive disease of lettuce in California. Verticillium resistance 1 (Vr1) confers resistance to race 1 isolates but is defeated by race 2 isolates, which are predicted to increase in prevalence. Three Plant Introductio...

  3. Fate of Escherichia coli O157:H7 in field-inoculated lettuce.

    Moyne, Anne-Laure; Sudarshana, Mysore R; Blessington, Tyann; Koike, Steven T; Cahn, Michael D; Harris, Linda J

    2011-12-01

    Impact of drip and overhead sprinkler irrigation on the persistence of attenuated Escherichia coli O157:H7 in the lettuce phyllosphere was investigated using a split-plot design in four field trials conducted in the Salinas Valley, California, between summer 2007 and fall 2009. Rifampicin-resistant attenuated E. coli O157:H7 ATCC 700728 (BLS1) was inoculated onto the soil beds after seeding with a backpack sprayer or onto 2- or 4-week-old lettuce plant foliage with a spray bottle at a level of 7 log CFU ml⁻¹. When E. coli O157:H7 was inoculated onto 2-week-old plants, the organism was recovered by enrichment in 1 of 120 or 0 of 240 plants at 21 or 28 days post-inoculation, respectively. For the four trials where inoculum was applied to 4-week-old plants, the population size of E. coli O157:H7 declined rapidly and by day 7, counts were near or below the limit of detection (10 cells per plant) for 82% or more of the samples. However, in 3 out 4 field trials E. coli O157:H7 was still detected in lettuce plants by enrichment 4-weeks post-inoculation. Neither drip nor overhead sprinkler irrigation consistently influenced the survival of E. coli O157:H7 on lettuce. PMID:21925023

  4. Comparison of prediction methods for the uptake of As, Cd and Pb in carrot and lettuce

    Legind, Charlotte Nielsen; Trapp, Stefan

    2010-01-01

    background scenario, the NMF and other models predicted the concentrations in carrot and lettuce within the range of measured values. Regressions considering soil pH, organic matter and clay content were not superior to simple transfer factors. The transfer from air to plant is significant, at least under...

  5. LETTUCE AND BROCCOLI RESPONSE AND SOIL PROPERTIES RESULTING FROM TANNERY WASTE APPLICATIONS

    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...

  6. Monitoring of pesticide residues in apples, lettuce and potato of the Slovene origin, 2001-04.

    Cesnik, H Basa; Gregorcic, A; Bolta, S Velikonja; Kmecl, V

    2006-02-01

    Apples, lettuce and potatoes (404 samples) produced in the Republic of Slovenia were analysed for pesticide residues at the Agricultural Institute of Slovenia, Ljubljana, in 2001-04. Sampling from eight agricultural production areas was performed at market producers at the harvesting of products or in storehouses after the pre-harvest interval of plant protection products used. Samples exceeding the maximum residue levels were the following: three apple samples (2.0%) containing 0.33-2.24 mg kg(-1) (phosalone and tolylfluanid), three lettuce samples (3.1%) containing 0.14-6.36 mg kg(-1) (dimethoate, dithiocarbamates and metalaxyl) and 36 potato samples (23.1%) containing 0.06-0.51 mg kg(-1) (dithiocarbamates). Residues of two or more active substances were found in 73 apple samples (48.3%), of which the maximum residue limit (MRL) was exceeded by three samples (2.0%) with the values ranging from 0.33 to 2.24 mg kg(-1), and nine lettuce samples (9.3%), for which the MRL was exceeded by three samples (3.1%) with values from 0.14 to 6.36 mg kg(-1). In potato samples, only residues of dithiocarbamates or no residues at all were found. Residues of the dithiocarbamate group were the most frequently found, i.e. in 66 apple samples (43.7%), 30 lettuce samples (30.9%) and 38 potato samples (24.4%). PMID:16449059

  7. Sanitizer solutions containing detergents for inactivation of Escherichia coli O157:H7 on romaine lettuce

    Numerous Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh lettuce. The development of effective and easily implemented wash treatment could reduce such incidents. The purpose of this study was to evaluate the addition of food-grade detergents to sanitizer solutions for i...

  8. Banded cucumber beetle (Coleoptera: Chrysomelidae) resistance in romaine lettuce: understanding latex chemistry

    Many plants subjected to herbivore damage exude latex, a rich source of biochemicals, which play important roles in host plant resistance. Our previous studies showed that fresh latex from Valmaine, a resistant cultivar of romaine lettuce Lactuca sativa L., applied to artificial diet is highly deter...

  9. Differential Persistence of E. coli O157:H7 Strains on Romaine Lettuce Leaves

    Outbreaks associated with leafy greens have focused attention on the persistence of Escherichia coli O157:H7 on produce. Limited information is available on ecological interactions influencing persistence of different E. coli O157:H7 strains on lettuce. Survival of six strains of E. coli O157:H7 i...

  10. Population biology of Verticillium dahliae isolates from lettuce in the Sallinas Valley of Californis.

    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...

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

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

  12. Sanitizer Solutions Containing Detergents for Inactivation of Escherichia coli O157:H7 on Romaine Lettuce

    Introduction: Numerous Escherichia coli O157:H7 outbreaks have been linked to consumption of fresh lettuce. The development of effective and easily implemented wash treatment could reduce such incidents. Purpose: The purpose of this study was to evaluate the addition of food-grade detergents to sa...

  13. Nucleotide sequence and genomic organization of an ophiovirus associated with lettuce big-vein disease

    Wilk, van der F.; Dullemans, A.M.; Verbeek, M.; Heuvel, van den J.F.J.M.

    2002-01-01

    The complete nucleotide sequence of an ophiovirus associated with lettuce big-vein disease has been elucidated. The genome consisted of four RNA molecules of approximately 7ò8, 1ò7, 1ò5 and 1ò4 kb. Virus particles were shown to contain nearly equimolar amounts of RNA molecules of both polarities. Th

  14. Analysis of ADP-glucose pyrophosphorylase expression during turion formation induced by abscisic acid in Spirodela polyrhiza (greater duckweed

    Wang Wenqin

    2012-01-01

    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.

  15. THE SECOND INFLUENCE OF SOIL OIL POLLUTION VARIOUS LEVELS ON THE PROCESSES OF WHEAT AND LETTUCE GERMINATION

    Borodulina, T.; Polonskiy, V.

    2011-01-01

    It is determined in the laboratory experiments, that at the initial maximal concentration of oil in soil (9 g/kg) which earlier was used for cultivation of 40 days plants of wheat and 30 days plants of lettuce, there is a decrease in the inhibitive second influence of oil on the parameters of wheat seedling growth and on lettuce seed germination rate, in comparison with the conditions when oil was brought directly before the experiment. It is revealed that lettuce growing decreased oil negati...

  16. Erigeron bonariensis: hospedeira alternativa do Lettuce mosaic virus no Brasil

    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.

  17. Production characteristics of lettuce Lactuca sativa L. in the frame of the first crop tests in the Higher Plant Chamber integrated into the MELiSSA Pilot Plant

    Tikhomirova, Natalia; Lawson, Jamie; Stasiak, Michael; Dixon, Mike; Paille, Christel; Peiro, Enrique; Fossen, Arnaud; Godia, Francesc

    Micro-Ecological Life Support System Alternative (MELiSSA) is an artificial closed ecosystem that is considered a tool for the development of a bioregenerative life support system for manned space missions. One of the five compartments of MELiSSA loop -Higher Plant Chamber was recently integrated into the MELiSSA Pilot Plant facility at Universitat Aut`noma deo Barcelona. The main contributions expected by integration of this photosynthetic compartment are oxygen, water, vegetable food production and CO2 consumption. Production characteristics of Lactuca sativa L., as a MELiSSA candidate crop, were investigated in this work in the first crop experiments in the MELiSSA Pilot Plant facility. The plants were grown in batch culture and totaled 100 plants with a growing area 5 m long and 1 m wide in a sealed controlled environment. Several replicates of the experiments were carried out with varying duration. It was shown that after 46 days of lettuce cultivation dry edible biomass averaged 27, 2 g per plant. However accumulation of oxygen in the chamber, which required purging of the chamber, and decrease in the food value of the plants was observed. Reducing the duration of the tests allowed uninterrupted test without opening the system and also allowed estimation of the crop's carbon balance. Results of productivity, tissue composition, nutrient uptake and canopy photosynthesis of lettuce regardless of test duration are discussed in the paper.

  18. Simultaneous detection of fluquinconazole and flusilazole in lettuce using gas chromatography with a nitrogen phosphorus detector: decline patterns at two different locations.

    Im, So Jeong; Rahman, Md Musfiqur; Abd El-Aty, A M; Kim, Sung-Woo; Kabir, Humayun; Farha, Waziha; Lieu, Truong; Lee, Young-Jun; Jung, Da-I; Choi, Jeong-Heui; Shin, Ho-Chul; Im, Geon-Jae; Hong, Su-Myeong; Shim, Jae-Han

    2016-06-01

    Method validations in addition to decline patterns of fluquinconazole and flusilazole in lettuce grown under greenhouse conditions at two different locations were investigated. Following the application of fluquinconazole and flusilazole at a dose rate of 20 mL/20 L water, lettuce samples were collected randomly for up to 7 days post-application, and simultaneously extracted with acetone, purified through solid-phase extraction, analyzed via gas chromatography with a nitrogen phosphorus detector, and confirmed through gas chromatography-mass spectrometry. The linearity was excellent, with determination coefficients (R(2) ) between 0.9999 and 1.0. The method was validated in triplicate at two different spiking levels (0.2 and 1.0 mg/kg) with satisfactory recoveries between 75.7 and 97.9% and relative standard deviations of <9. The limit of quantification was 0.01 mg/kg. Both analytes declined very quickly, as can be seen from the short half-life time of <4 days. Statistical analysis revealed significant differences between residues at different days of sampling, except at 7 days post-application (triple application). At that point, the decline patterns of fluquinconazole and flusilazole were independent of application rate, location, temperature and humidity. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26480018

  19. Cadmium determination in lettuce grown in contaminated soil by INAAA and GFAAS

    Armelin, Maria Jose A.; Maihara, Vera A.; Saiki, Mitiko, E-mail: marmelin@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Trevizam, Anderson R.; Silva, Maria Ligia S. [Universidade Estadual do Centro Oeste (UNICENTRO), Guarapuava, PR (Brazil); Muraoka, Takashi, E-mail: muraoka@cena.usp.b [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil)

    2011-07-01

    Although Cd is not essential for the mammalian organism, it follows in body the same pathways of essential elements such as zinc and copper. There is evidence that the Cd induced reduction of Ca absorption, may lead to the development of osteoporosis. Anthropogenic activities associated with industrial activities, mining and use of fertilizers, limestone pesticides in agriculture are the main sources of Cd enrichment in soils. Due to the possibility that Cd being absorbed by plants and through them to reach the food chain, interest has increased in regard to developing techniques for remediation of contaminated sites. The addition of substances capable of immobilizing the toxic elements from the soil is a procedure that has been used for remediation of contaminated sites. The function of these substances is to reduce the mobility and bioavailability of potentially toxic elements in the soil. In this study, five doses of phosphorus as triple phosphorus were used in a number of lettuce plants grown in contaminated soil. The concentration of Cd present in lettuce leaves treated with phosphate was compared with the Cd absorbed by the control plant leaves. Instrumental Neutron Activation Analysis (INAA) and Graphite-Furnace Absorption Atomic Spectrometry (GFAAS) were the analytical methods used to determine Cd contents in lettuce leaves. The objective was to evaluate the performance of the employed analytical methods: INAA and GFAAS in the assessment of the efficiency of phosphorus treatments to reduce the Cd concentrations in leaves of lettuce. Results obtained indicated that both analytical methods were efficient to discriminate the response of Cd concentration in lettuce as a function of soil treatment with phosphorus. Although INAA has shown a positive performance in this study, GFAAS seemed more appropriate because its sensitivity was much higher than that obtained by INAA, in the experimental conditions. (author)

  20. Parasitization of commercially available parasitoid species against the lettuce aphid, Nasonovia ribisnigri (Hemiptera: Aphididae).

    Shrestha, G; Skovgård, H; Enkegaard, A

    2014-12-01

    The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. Little documentation exists for the control efficacy of aphid parasitoids against N. ribisnigri. This laboratory study evaluated three commercially available parasitoid species: Aphidius colemani (Viereck), Lysiphlebus testaceipes (Cresson), and Aphelinus abdominalis (Dalman) for their mortality impact on N. ribisnigri. The green peach aphid Myzus persicae (Sulzer) was included as a reference aphid. The study showed that A. abdominalis successfully parasitized 39 and 13% of the offered N. ribisnigri and M. persicae, respectively, within a 24-h exposure period. In contrast, none of the lettuce aphids exposed to Ap. colemani or L. testaceipes were successfully parasitized, whereas 60 and 3.5% of M. persicae, respectively, were successfully parasitized within a 6-h exposure period. Lettuce aphid mortality due to incomplete parasitization was 26 and 31% when exposed to Ap. colemani and L. testaceipes, respectively, with corresponding values for M. persicae being 5 and 10%, respectively. Mortality as a result of incomplete parasitization when aphids were exposed to A. abdominalis was low for both aphid species. The total mortality inflicted by A. abdominalis within a 24-h exposure period was 51% for the lettuce aphids and significantly less (19%) for green peach aphids. In contrast, Ap. colemani inflicted a higher mortality in M. persicae (65%) compared with N. ribisnigri (26%) within a 6-h exposure period. L. testaceipes caused a greater mortality in N. ribisnigri as compared with M. persicae. This study concludes that A. abdominalis has the potential to be used against N. ribisnigri in inoculative biocontrol programs as compared with the other parasitoid species based on successful parasitization. PMID:25290653

  1. Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 2: validation.

    Cook, N; Paton, C A; Wilkinson, N; Nichols, R A B; Barker, K; Smith, H V

    2006-06-15

    We report the results of interlaboratory collaborative trials of methods to detect oocysts of the protozoan parasite Cryptosporidium parvum on lettuce and raspberries. The trials involved eight expert laboratories in the United Kingdom. Samples comprised 30 g lettuce, and 60 g raspberries. Lettuce samples were artificially contaminated at three levels: low (8.5-14.2 oocysts), medium (53.5-62.6 oocysts), and high (111.3-135.0 oocysts). Non-contaminated lettuce samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated lettuce samples) of 89.6%, and a specificity (correct identification of non-contaminated samples) of 85.4%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 30.4%. The method was just as reproducible between laboratories, as repeatable within a laboratory. Raspberry samples were artificially contaminated at three levels: low (8.5-26.8 oocysts), medium (29.7-65.7 oocysts), and high (53.9-131.3 oocysts). Non-contaminated raspberry samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated raspberry samples) of 95.8%, and a specificity (correct identification of non-contaminated samples) of 83.3%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 44.3%. The method was just as reproducible between laboratories, as repeatable within a laboratory. The results of the collaborative trial indicate that these assays can be used effectively in analytical microbiological laboratories. PMID:16546283

  2. Reduction of Escherichia coli 0157:H7 in shredded iceberg lettuce by chlorination and gamma irradiation

    Lettuce was inoculated with a six-strain cocktail of acid-adapted Escherichia coli 0157:H7 at a level of 1x107 CFU/g. Following chlorination at 200 μg/ml, the lettuce was irradiated at 0.15, 0.38, or 0.55 kGy using a 60Co source. Survival of E. coli 0157:H7, aerobic mesophiles and yeast and molds were measured over a period of 10 days. For quality analysis, chlorinated lettuce was subjected to irradiation at 0.33 and 0.53 kGy and stored at 1.0 deg. C, 4.0 deg. C or 7.0 deg. C. Changes in texture and color were determined by instrumental means and changes in flavor, odor, and visual quality were determined by sensory testing. Chlorination plus irradiation at 0.55 kGy produced a 5.4-log reduction in E. coli 0157:H7 levels. Chlorination alone reduced the E. coli 0157:H7 counts by 1-2 logs. Irradiation at 0.55 kGy was also effective in reducing standard plate counts and yeast and mold counts. Irradiation at this level did not cause softening of lettuce and sensory attributes were not adversely affected. In general, appearance and flavor were affected more by the length of storage than by temperature conditions. The 5+log reduction in E. coli counts and lack of adverse effects on sensory attributes indicate that low-dose irradiation can improve the safety and shelf-life of fresh-cut iceberg lettuce for retail sale or food service

  3. Reduction of Escherichia coli 0157:H7 in shredded iceberg lettuce by chlorination and gamma irradiation

    Foley, D.M. E-mail: dfoley@chapman.edu; Dufour, A.; Rodriguez, L.; Caporaso, F.; Prakash, A

    2002-03-01

    Lettuce was inoculated with a six-strain cocktail of acid-adapted Escherichia coli 0157:H7 at a level of 1x10{sup 7} CFU/g. Following chlorination at 200 {mu}g/ml, the lettuce was irradiated at 0.15, 0.38, or 0.55 kGy using a {sup 60}Co source. Survival of E. coli 0157:H7, aerobic mesophiles and yeast and molds were measured over a period of 10 days. For quality analysis, chlorinated lettuce was subjected to irradiation at 0.33 and 0.53 kGy and stored at 1.0 deg. C, 4.0 deg. C or 7.0 deg. C. Changes in texture and color were determined by instrumental means and changes in flavor, odor, and visual quality were determined by sensory testing. Chlorination plus irradiation at 0.55 kGy produced a 5.4-log reduction in E. coli 0157:H7 levels. Chlorination alone reduced the E. coli 0157:H7 counts by 1-2 logs. Irradiation at 0.55 kGy was also effective in reducing standard plate counts and yeast and mold counts. Irradiation at this level did not cause softening of lettuce and sensory attributes were not adversely affected. In general, appearance and flavor were affected more by the length of storage than by temperature conditions. The 5+log reduction in E. coli counts and lack of adverse effects on sensory attributes indicate that low-dose irradiation can improve the safety and shelf-life of fresh-cut iceberg lettuce for retail sale or food service.

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

    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.

  5. Expression of the mouse metallothionein mutant ββ-cDNA in the lettuces (Lactuca sativa L.)

    2002-01-01

    Mouse metallothionein (MT) domain mutant ββ-cDNA gene has been inserted into the plant expression vector pGPTVd35S which has herbicide (PPT)-resistance gene bar as a selective marker. The chimeric gene was introduced into the lettuce (Lactuca sativa L. cv Salinas 88) by Agrobacterium-mediated transformation. PCR and Southern blot analysis of some putative transformants indicated that the introduced ββ-cDNA was integrated into lettuce genome and inheritted by sexual reproduction. The expression of ββ gene in lettuce plants was demonstrated by Northern and Western blot analysis. Meanwhile, the zinc content of the transformed lettuce plants is up to 400 μg/g dry weight, remarkably higher than the control plants.

  6. Kinetics of basic dye (methylene blue) biosorption by giant duckweed (Spirodela polyrrhiza)

    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

  7. Sorption equilibrium of emerging and traditional organic contaminants in leafy rape, Chinese mustard, lettuce and Chinese cabbage.

    Yang, Chien-Ying; Chang, Meei-Ling; Wu, Siang Chen; Shih, Yang-Hsin

    2016-07-01

    Emerging and petroleum contaminants could transfer into food chains by plant uptake, potentially causing food security problems. To build a prediction model, the sorption equilibrium and uptake kinetics of toluene, p-xylene, naphthalene, bisphenol A, and 4-bromo-diphenyl ether in some common leafy vegetables including leafy rape, Chinese mustard, lettuce and Chinese cabbage were examined. The kinetic experiments revealed that high sorption rates were observed for these plants that had high lipid contents. For two emerging contaminants with polar functional groups, their resulting isotherms were strongly linear (R(2) = 0.92 to 1.00), indicating that the sorption was dominated by partitioning. Moreover, regression correlation showed that log Klip, the lipid-water partition coefficient, and log Kow, the octanol-water coefficient, for these organic chemicals were strongly linear-related, following the equation: log Klip = 0.894 × log Kow+0.219 (R(2) = 0.953). The correlation equation allows the prediction of the sorption capacity of plant species for an organic compound when the plant composition and the log Kow of the chemical are determined. This improved model containing different organic chemicals with a wide range of log Kow (2.73-4.80) and including emerging contaminants was established, which shows further utilization for predicting the sorption of organic contaminants by plants. PMID:27085315

  8. High-throughput sequencing of three Lemnoideae (duckweeds chloroplast genomes from total DNA.

    Wenqin Wang

    Full Text Available BACKGROUND: Chloroplast genomes provide a wealth of information for evolutionary and population genetic studies. Chloroplasts play a particularly important role in the adaption for aquatic plants because they float on water and their major surface is exposed continuously to sunlight. The subfamily of Lemnoideae represents such a collection of aquatic species that because of photosynthesis represents one of the fastest growing plant species on earth. METHODS: We sequenced the chloroplast genomes from three different genera of Lemnoideae, Spirodela polyrhiza, Wolffiella lingulata and Wolffia australiana by high-throughput DNA sequencing of genomic DNA using the SOLiD platform. Unfractionated total DNA contains high copies of plastid DNA so that sequences from the nucleus and mitochondria can easily be filtered computationally. Remaining sequence reads were assembled into contiguous sequences (contigs using SOLiD software tools. Contigs were mapped to a reference genome of Lemna minor and gaps, selected by PCR, were sequenced on the ABI3730xl platform. CONCLUSIONS: This combinatorial approach yielded whole genomic contiguous sequences in a cost-effective manner. Over 1,000-time coverage of chloroplast from total DNA were reached by the SOLiD platform in a single spot on a quadrant slide without purification. Comparative analysis indicated that the chloroplast genome was conserved in gene number and organization with respect to the reference genome of L. minor. However, higher nucleotide substitution, abundant deletions and insertions occurred in non-coding regions of these genomes, indicating a greater genomic dynamics than expected from the comparison of other related species in the Pooideae. Noticeably, there was no transition bias over transversion in Lemnoideae. The data should have immediate applications in evolutionary biology and plant taxonomy with increased resolution and statistical power.

  9. Ethylene and lettuce seed germination Etileno e a germinação de sementes de alface

    Warley Marcos Nascimento

    2003-01-01

    Ethylene can stimulate seed germination and overcome dormancy in many species. For instance, the inhibitory effect of high temperature on lettuce seed germination can be overcome by exogenous ethylene. Involvement of ethylene in seed germination is a widely accepted fact, but the mechanistic details are poorly understood. A critical factor in ethylene studies is the response of seed germination properties to various ethylene inhibitors. Lettuce seed has been used as a model to study the role ...

  10. Influence of transplant size on the above- and below-ground performance of four contrasting field-grown lettuce cultivars

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

    2013-01-01

    Background and aims: Modern lettuce cultivars underperform under conditions of variable temporal and spatial resource availability, common in organic or low-input production systems. Information is scarce on the impact of below-ground traits on such resource acquisition and performance of field-grown lettuce; exploring genetic variation in such traits might contribute to strategies to select for robust cultivars, i.e., cultivars that perform well in the field, even under stress. Methods: To i...

  11. POST HARVEST TRANSMISSION OF Salmonella enterica TO THE ROOTS AND LEAVES OF BUTTERHEAD LETTUCE PACKAGED WITH INTACT ROOTS

    Waitt, Jessie Anne

    2013-01-01

    In the United States, illnesses associated with fresh produce are increasing in frequency.  While contamination risks are present at every aspect of the farm to fork continuum, post-harvest practices holds the potential for cross-contamination of large amounts of product.  Post-harvest contamination risks for hydroponically grown lettuce packaged with intact roots and sold as "®living lettuce"" are poorly understood.  In this study, transmission of Salmonella enterica serotype Enteritidis to ...

  12. RECENT CHANGES IN MARKETING AND TRADE PRACTICES IN THE U.S. LETTUCE AND FRESH-CUT VEGETABLE INDUSTRIES

    Handy, Charles R.; Thompson, Gary D.; Glaser, Lewrene K.

    2001-01-01

    Fifteen lettuce and bagged salad shippers were interviewed as part of a larger study on changes in produce marketing. Retail consolidation, changes in technology, and increased consumer demand for convenience, product diversity, and year-round availability have all influenced shipper-retailer relations. The interviewed firms provided more fees and services to retail buyers in 1999 than 1994. Most of the bagged salad shippers paid slotting fees, while none of the lettuce shippers were currentl...

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

    Shrestha, Govinda; Enkegaard, Annie; Steenberg, Tove

    2015-01-01

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

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

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

    2012-08-01

    Fresh-cut Iceberg lettuce packaged in modified atmosphere packages and spinach in perforated film bags were irradiated with gamma rays at doses of 0, 1, 2, 3, and 4 kGy. After irradiation, the samples were stored for 14 days at 4 °C. 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.

  15. Evapotranspiration-based irrigation scheduling of lettuce and broccoli

    Estimation of crop evapotranspiration supports efficient irrigation water management, which in turn supports water conservation, mitigation of groundwater depletion/degradation, energy savings, and crop quality maintenance. Past research in California has revealed strong relationships between fract...

  16. QTL for shelf life in lettuce co-locate with those for leaf biophysical properties but not for leaf developmental traits

    Zhang, Fang Z.; Wagstaff, Carol; Rae, Anne M; Sihota, Arinder K.; Keevil, C. William; Rothwell, Steve D.; Clarkson, Graham J. J.; Michelmore, Richard W; Truco, Maria Jose; Dixon, Mark S.; Taylor, Gail

    2007-01-01

    Developmental and biophysical leaf characteristics that influence post-harvest shelf life in lettuce, an important leafy crop, have been examined. The traits were studied using 60 informative F9 recombinant inbreed lines (RILs) derived from a cross between cultivated lettuce (Lactuca sativa cv. Salinas) and wild lettuce (L. serriola acc. UC96US23). Quantitative Trait Loci (QTL) for shelf life co-located most closely with those for leaf biophysical properties such as plasticity, elasticity and...

  17. Enhanced accumulation of vitamins, nutraceuticals and minerals in lettuces associated with arbuscular mycorrhizal fungi (AMF): a question of interest for both vegetables and humans

    Marouane Baslam; Nieves Goicoechea; Idoia Garmendia

    2013-01-01

    Lettuce ( Lactuca sativa L.) is extensively grown and is the most widely used food crop for the called “Fourth Range†of vegetables. Lettuce exhibits healthy properties mainly due to the presence of antioxidant compounds (vitamins C and E, carotenoids, polyphenols) alongside significant fibre content and useful amounts of certain minerals. Lettuce can establish a mutualistic association with arbuscular mycorrhizal fungi (AMF). The establishment of the symbiosis involves a continuous cellul...

  18. 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

    María Roberta Ansorena

    2012-06-01

    Full Text Available 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 this 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 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. Neste 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 conte

  19. Toxic Effects of Acetochlor,Butachlor and their Compound Pollution on Duckweed%乙草胺、丁草胺及其复合污染对浮萍的毒性效应研究,

    梁卫玲; 唐美珍; 王艳娜

    2012-01-01

    以浮萍(LemnaSPP)为研究对象,浮萍过氧化物酶的活性为探讨物,研究了除草剂乙草胺、丁草胺对浮萍生长的单一毒性和联合毒性效应。结果表明:低浓度的乙草胺能够促进浮萍POD的活性,高浓度的乙草胺则抑制浮萍POD的活性,当乙草胺浓度为7.65mg/L时,浮萍POD的活性最高,激活率可达6.29%,当其浓度达到25.5mg/L时,浮萍POD的活性最低,其浓度为229.50mg/L时,对浮萍POD的抑制率最大,可达25.28%;低浓度的丁草胺能够促进浮萍POD的活性,高浓度的丁草胺则抑制浮萍POD的活性,当丁草胺浓度为2.496mg/L时,浮萍POD的活性最高,激活率可达22.68%,当其浓度达到24.96mg/L时,浮萍POD的活性最低,当其浓度为37.44mg/L时,对浮萍POD的抑制率最大,可达22.68%;乙草胺-丁草胺复合污染对浮萍POD活性的影响表现出拮抗作用,且当乙草胺浓度为229.5mg/L,丁草胺浓度为49.92mg/L时,乙草胺一丁草胺对浮萍POD活性的抑制率最大可达32.54%,在一定范围内,当浓度继续增加,联合毒性作用表现出相对的增加趋势。%Taking the duckweed (Lemna s p p) as the object of study,and using duckweed peroxidase activity as exploring object,this article studies the sole toxicity and the union poisonous effect of weed killer aceto- chlor and butachlor on duckweed growth. The results show. (1)The low concentration acetochlor can pro- mote the duckweed POD activeness,and the highly concentrated acetochlor suppress it;when the acetochlor density is 7.65mg/L,the duckweed POD activeness is highest,and activation rates is up to 6.29% ;when its density achieved at 25.5mg/L,the duckweed POD activeness is lowest,and the greatest inhibition rate is up to 25.28%;(2)The low concentration butachlor can promote the duckweed POD activeness,and the highly concentrated butachlor suppress it;when butachlor

  20. Effect of nitrogen and fish manure fertilization on growth and chemical composition of lettuce

    Yildirim, Ertan; Kul, Raziye; Turan, Metin; Ekinci, Melek; Alak, Gonca; Atamanalp, Muhammet

    2016-04-01

    Present experiment was designed to determine the response of various dozes of fish manure (FM) and commercial fertilizers on plant growth, yield and nutrient content of lettuce. The treatments consisted of fish manure, commercial fertilizer and the combination of fish manure and commercial fertilizer with four dozes of nitrogen (0 kg/ha, 100 kg/ha, 150 kg/ha and 200 kg/ha). The results of the study showed that treatments significantly affected the growth and chemical characteristics of lettuce. The best results in regard to plant growth and yield were obtained from 100 and 150 kg kg/ha nitrogen dozes of the combination of fish manure and commercial fertilizer.

  1. Phosphorus levels in soil and lettuce production due to phosphorus fertilization

    José Ricardo Mantovani

    2014-09-01

    Full Text Available The leafy vegetables are considered nutrient-demanding, but are scarce in the literature works about phosphorus fertilization. This study aimed to evaluate the effect of phosphate on the production of lettuce, content and amount of P accumulated in leaf plants, and to relate levels of P in the clayey soil with plant production. The experiment was conducted in a greenhouse in pots in a randomized block design with ten treatments and four replications. The treatments were made up of P, corresponding to 0, 50, 100, 150, 200, 300, 400, 500, 600 and 700 mg dm-3, as triple superphosphate powder. Portions of 6 dm3 of the clay soil (420 g kg-1 clay received lime, aimed at raising the V % soil to 70 %, equivalent to 20 t ha-1 of cattle manure, and the phosphate fertilizer according to the treatments, remaining incubated for about 30 days. At the end of incubation, each pot received a change of lettuce cultivar Verônica. The plant harvesting was performed 39 days after transplanting the seedlings. O P gave large increases in growth and production of lettuce, and culture responded positively to the application of high doses of the nutrient. A dose of 350 mg dm-3, equivalent to 800 kg ha-1 P2O5, was the most suitable for growing lettuce in the clay soil. In this work conditions, the phosphorus fertilizations it was necessary when the P-Mehlich contents in the clay soil were less than 75 mg dm-3.

  2. A Quantitative Dynamic Simulation of Bremia lactucae Airborne Conidia Concentration above a Lettuce Canopy.

    Fall, Mamadou Lamine; Van der Heyden, Hervé; Carisse, Odile

    2016-01-01

    Lettuce downy mildew, caused by the oomycete Bremia lactucae Regel, is a major threat to lettuce production worldwide. Lettuce downy mildew is a polycyclic disease driven by airborne spores. A weather-based dynamic simulation model for B. lactucae airborne spores was developed to simulate the aerobiological characteristics of the pathogen. The model was built using the STELLA platform by following the system dynamics methodology. The model was developed using published equations describing disease subprocesses (e.g., sporulation) and assembled knowledge of the interactions among pathogen, host, and weather. The model was evaluated with four years of independent data by comparing model simulations with observations of hourly and daily airborne spore concentrations. The results show an accurate simulation of the trend and shape of B. lactucae temporal dynamics of airborne spore concentration. The model simulated hourly and daily peaks in airborne spore concentrations. More than 95% of the simulation runs, the daily-simulated airborne conidia concentration was 0 when airborne conidia were not observed. Also, the relationship between the simulated and the observed airborne spores was linear. In more than 94% of the simulation runs, the proportion of the linear variation in the hourly-observed values explained by the variation in the hourly-simulated values was greater than 0.7 in all years except one. Most of the errors came from the deviation from the 1:1 line, and the proportion of errors due to the model bias was low. This model is the only dynamic model developed to mimic the dynamics of airborne inoculum and represents an initial step towards improved lettuce downy mildew understanding, forecasting and management. PMID:26953691

  3. The effects of nutrient solution sterilization on the growth and yield of hydroponically grown lettuce

    Schwartzkopf, S. H.; Dudzinski, D.; Minners, R. S.

    1987-01-01

    Two methods of removing bacteria from hydroponic nutrient solution [ultraviolet (UV) radiation and submicronic filter] were evaluated for efficiency and for their effects on lettuce (Lactuca sativa L.) production. Both methods were effective in removing bacteria; but, at high intensity, the ultraviolet sterilizer significantly inhibited the production of plants grown in the treated solution. Bacterial removal by lower intensity UV or a submicronic filter seemed to promote plant growth slightly, but showed no consistent, statistically significant effect.

  4. Preventing thermoinhibition in a thermosensitive lettuce genotype by seed imbibition at low temperature

    Nascimento Warley Marcos

    2003-01-01

    Full Text Available Lettuce (Lactuca sativa L. seed germination is strongly temperature dependent and under high temperatures, germination of most of genotypes can be erratic or completely inhibited. Lettuce seeds of 'Dark Green Boston' (DGB were incubated at temperatures ranging from 15degrees to 35degreesC at light and dark conditions. Other seeds were imbibed in dark at 20degrees; 25degrees; 30degrees; and 35degreesC for 8 and 16 hours and then transferred to 20 or 35degreesC, in dark. Seeds were also incubated at constant temperature of 20degrees and 35 degreesC, in the dark, as control. In another treatment, seeds were primed for 3 days at 15degreesC with constant light. DGB lettuce seeds required light to germinate adequately at temperatures above 25degreesC. Seeds incubated at 20degreesC had 97% germination, whereas seeds incubated at 35degreesC did not germinate. Seeds imbibed at 20degreesC for 8 and 16 hours had germination. At 35degreesC, seeds imbibed initially at 20degreesC for 8 and 16 hours, had 89 and 97% germination, respectively. Seeds imbibed at 25degreesC for 16 hours, germinated satisfactory at 35degreesC. High temperatures of imbibition led to no germination. Primed and non-primed seeds had 100% germination at 20degreesC. Primed seeds had 100% germination at 35degreesC, whereas non-primed seeds germinate only 4%. The first hours of imbibition are very critical for lettuce seed germination at high temperatures.

  5. Dynamics of nonpersistent aphid-borne viruses in lettuce crops covered with UV-absorbing nets.

    Legarrea, S; Betancourt, M; Plaza, M; Fraile, A; García-Arenal, F; Fereres, A

    2012-04-01

    Aphid-transmitted viruses frequently cause severe epidemics in lettuce grown under Mediterranean climates. Spatio-temporal dynamics of aphid-transmitted viruses and its vector were studied on lettuce (Lactuca sativa L.) grown under tunnels covered by two types of nets: a commercial UV-absorbing net (Bionet) and a Standard net. A group of plants infected by Cucumber mosaic virus (CMV, family Bromoviridae, genus Cucumovirus) and Lettuce mosaic virus (LMV, family Potyviridae, genus Potyvirus) was transplanted in each plot. The same virus-infected source plants were artificially infested by the aphid Macrosiphum euphorbiae (Thomas). Secondary spread of insects was weekly monitored and plants were sampled for the detection of viruses every two weeks. In 2008, the infection rate of both CMV and LMV were lower under the Bionet than under the Standard cover, probably due to the lower population density and lower dispersal rate achieved by M. euphorbiae. However, during spring of 2009, significant differences in the rate of infection between the two covers were only found for LMV six weeks after transplant. The spatial distribution of the viruses analysed by SADIE methodology was "at random", and it was not associated to the spatial pattern of the vector. The results obtained are discussed analyzing the wide range of interactions that occurred among UV-radiation, host plant, viruses, insect vector and environmental conditions. Our results show that UV-absorbing nets can be recommended as a component of an integrated disease management program to reduce secondary spread of lettuce viruses, although not as a control measure on its own. PMID:22226944

  6. Biopreservative methods to control the growth of foodborne pathogens on fresh-cut lettuce.

    Oliveira, M; Abadias, M; Colás-Medà, P; Usall, J; Viñas, I

    2015-12-01

    Fruits and vegetables can become contaminated by foodborne pathogens such as Escherichia coli O157:H7, Salmonella and Listeria monocytogenes, and it has been demonstrated that current industrial sanitizing treatments do not eliminate the pathogens when present. Chemical control is widely used, but biological control appears to be a better solution, mainly using the native microbiota present on fresh produce. The first objective of this study was to isolate native microbiota from whole and fresh-cut produce and to determine whether these bacteria were antagonistic toward foodborne pathogens. A total of 112 putative antagonist isolates were screened for their ability to inhibit the growth of Salmonella enterica on lettuce disks. Five different genera reduced S. enterica growth more than 1-log unit at 20°C at the end of 3 days. When tested against L. monocytogenes 230/3, only Pseudomonas sp. strain M309 (M309) was able to reduce pathogen counts by more than 1-log unit. Therefore, M309 strain was selected to be tested on lettuce disks at 10°C against S. enterica, E. coli O157:H7 and L. monocytogenes. M309 strain was only able to reduce S. enterica and E. coli O157:H7 populations. The second objective was to test different biopreservative methods including M309 strain, Pseudomonas graminis CPA-7 (CPA-7), bacteriophages (Listex P100 and Salmonelex) and nisin at conditions simulating commercial applications against Salmonella and L. monocytogenes on fresh-cut lettuce. The addition of the biopreservative agents did not result in a significant reduction of Salmonella population. However, CPA-7 strain together with nisin reduced L. monocytogenes numbers after 6 days of storage at 10°C. The cocktail of Salmonella and L. monocytogenes was not markedly inactivated by their respective bacteriophage solutions. This study highlighted the potential of biocontrol, but the combination with other technologies may be required to improve their application on fresh-cut lettuce. PMID

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

    Kooistra, T

    1983-01-01

    The basal parts of maturing glasshouse lettuce can be attacked by several soil fungi, which cause bottom rot. Until recently quintozene was generally applied against this disease complex. The study of the causal fungi - especially Rhizoctonia solani - and their control was undertaken in view of the need for quintozene replacing fungicides.A survey revealed that Botrytis cinerea was the most frequently observed pathogen, especially in winter crops. The incidence of Sclerotinia minor, Sclerotin...

  8. Influence of nickel nutrition and nitrogen source on growth and yield of lettuce in hydroponic culture

    F. Hosseini

    2012-06-01

    Full Text Available Nickel (Ni is the most recently discovered essential element for higher plants. But there is limited information about the effect of this element on yield and nitrogen (N metabolism of different plants. In this research, the interaction of Ni supplement and N source was studied on nitrate accumulation and growth of lettuce (Lactuca sativa L. cv. Baker in solution culture. In a greenhouse experiment, lettuce plants were exposed to two Ni levels (0 and 0.04 µM in the form of NiCl2 and three N levels (5, 10, and 20 µM in the form of urea and ammonium nitrate. The plants were harvested 6 weeks after transplanting and the fresh weight of shoots and roots, total N concentration, nitrate concentration and Fe content of shoots were determined. The results indicated that shoot and root fresh weight of nitrate-fed plants were higher than urea-fed plants. Ni nutrition significantly enhanced the yield of urea-fed plants. The shoot nitrate concentration in nitrate-fed plants was significantly greater in comparison with urea-fed plants. On the other hand, nitrate concentration in the shoots of lettuce plants decreased significantly with Ni nutrition. Ni supplementation in urea-fed plants increased the shoot Fe content. The shoot concentration of total-N in the urea-fed plants increased with the Ni supplement. While, Ni had no significant effect on shoot concentration of total-N in the nitrate-fed plants. Addition of low levels of Ni to the nutrient solution, particularly to the urea-containing solution, improved the yield of lettuce. In addition, these plant leaves are safer for human consumption because the shoot nitrate content is significantly reduced by application of Ni.

  9. Evolution of nitrate level in green lettuce conventional grown under natural conditions and aquaponic system

    Flavius Blidariu; Drasovean Alexandru; Grozea Adrian; Radulov Isidora; Lalescu Dacian

    2013-01-01

    Aquaponics integrates growing plants without soil technology with aquaculture, having an important role in recovery of nutrients from effluents. The research aimed to evaluate nitrates level in lettuce (Lactuca sativa) conventional grown under natural conditions and in integrated aquaponic system with a recirculated aquaculture system designed for pikeperch growth (Sander lucioperca). Conventional production (54 plants) has been obtained in the field without fertilizer or pesticide management...

  10. Carotenoids of Lettuce (Lactuca sativa L.) Grown on Soil Enriched with Spent Coffee Grounds

    Susana Casal; Sara Cunha; José Alberto Pereira; Rebeca Cruz; Paula Baptista

    2012-01-01

    The impact of spent coffee grounds on carotenoid and chlorophyll content in lettuce (Lactuca sativa L. var. capitata) was evaluated. A greenhouse pot experiment was conducted with spent coffee amounts ranging from 0% to 20% (v/v). All evaluated pigments increased proportionally to spent coffee amounts. Lutein and β-carotene levels increased up to 90% and 72%, respectively, while chlorophylls increased up to 61%. Biomass was also improved in the presence of 2.5% to 10% spent coffee, decreasing...

  11. Effete of Gamma Radiation and N.P.K on Lettuce yield

    Two field experiment were carried out during 2005/2006 winter growing seasons at the experiment at farm of Nuclear Research Center, Atomic Energy Authority, Inshas, Egypt – The experiments were conducted to study the effect of irradiated sowing seeds with 0, 2, 4, 6 and 8 Gray (Gy) of gamma radiation and / or the effect of different levels of NPK fertilizer 0, (NPK)1, (NPK)2, (NPK)3, (NPK)4 and (NPK)5 on the morphological and chemical parameters of the lettuce yield. The fresh weight of the plant in the line, length of the plant in the line, the number of leaves in the line, the number of plants in the line and the fresh weight in Fadden per ton were studied. There were significant effects of NPK contents on the lettuce leaves at (NPK) 4 in the dose level 6 Gy and on Calcium and Vitamins. We found that the most effective doses on leaf lettuce is 6 Gy dose of gamma radiation which gives strong and early seedlings in maturity upwards in the production of seedlings dose of 4 Gy. While the dose 8 Gray did not occur any increase at dose level 6 Gy. The Level (NPK) 4 increase the production of fresh per acre more upwards for all levels with 6 Gray and fourth level was the best in the natural qualities and characteristics of chemical terms of delay growth harvest lettuce, as well as influence on the plant content of calcium, nitrogen, protein and all the natural qualities among the first season and the second season.

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

    Jensen, Annette Nygaard; Storm, Christina; Baggesen, Dorte Lau; Forslund, A.; Dalsgaard, A.

    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 ...

  13. Effect of the soil type on the microbiome in the rhizosphere of field-grown lettuce

    Susanne eSchreiter; Guo-chun eDing; Holger eHeuer; Günter eNeumann; Martin eSandmann; Rita eGrosch; Siegfried eKropf; Kornelia eSmalla

    2014-01-01

    The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for ten years under the same agricultural management to reveal differences directly linked to the soil type and n...

  14. Insights into the economic viability of a new CEA system producing hydroponic lettuce

    Ilaslan, Gunes; White, Gerald B.; Langhans, Robert W.

    2002-01-01

    A new CEA (Controlled Environment Agriculture) system growing Boston lettuce, Lactuca Sativa cv. ‘Vivaldi’, achieves the same quality and quantity of production every day of the year. The year-round constant quantity and quality production indicate potential for success. However, our research showed that out of nine selected U.S. locations with different climatic and economic conditions, the Northeast had 25.7 percent higher production costs for the same yield. The analysis indicated that giv...

  15. Foliar fertilizations with boron and growth regulators on lettuce (Lactuca sativa L.) cv floresta culture

    The experiment was realized to verify the possibility of applying Boron as foliar fertilization with growth regulators: indol acetic acid, giberellic acid, ethephon and cycocel. The other objective was to compare the foliar and soil fertilization, with Boron, on the lettuce culture. The results showed that there wasn't difference of production between the treatments. Meanwhile the application of growth regulator modified the Boron grade in the leaves. (author)

  16. [Effect of outer space factors on lettuce seeds (Lactuca sativa) flown on "Kosmos" biosatellites].

    Nevzgodina, L V; Maksimova, E N; Akatov, Iu A; Kaminskaia, E V; Marennyĭ, A M

    1990-01-01

    The effect of cosmic radiation on air-dry lettuce (Lactuca sativa) seeds was investigated. It was attempted to discriminate the effects of cosmic ionizing radiation per se and its combination with solar light radiation. It was found that the number of aberrant cells in the seeds exposed to solar light was smaller than that of cells chielded with 0.0008 to 0.0035 g/cm2 foil which could be attributed to photoreactivity. PMID:2329764

  17. Effect of the soil type on the microbiome in the rhizosphere of field-grown lettuce

    Susanne eSchreiter

    2014-04-01

    Full Text Available The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for ten years under the same agricultural management to reveal differences directly linked to the soil type and not influenced by other factors such as climate or cropping history. Bulk soil and rhizosphere samples were collected three and seven weeks after planting. The analysis of 16S rRNA gene fragments amplified from total community DNA by denaturing gradient gel electrophoresis and pyrosequencing revealed soil type-dependent differences in the bacterial community structure of the bulk soils and the corresponding rhizospheres. The rhizosphere effect differed depending on the soil type and the plant growth developmental stage. Despite the soil type-dependent differences in the bacterial community composition several genera such as Sphingomonas, Rhizobium, Pseudomonas and Variovorax were significantly increased in the rhizosphere of lettuce grown in all three different soils. The number of rhizosphere responders was highest three weeks after planting. Interestingly, in the soil with the highest numbers of responders the highest shoot dry weights were observed. Heatmap analysis revealed that many dominant operational taxonomic units were shared among rhizosphere samples of lettuce grown in diluvial sand, alluvial loam, and loess loam and that only a subset was increased in relative abundance in the rhizosphere compared to the corresponding bulk soil. The findings of the study provide insights into the effect of soil types on the rhizosphere microbiome of lettuce.

  18. Physiological responses of seeds and seedlings of lettuce submitted to Philodendron bipinnatifidum extract

    Tiago Zanatta Aumonde; Emanuela Garbin Martinazzo; Tiago Pedó; Junior Borella; Luciano do Amarante; Francisco Amaral Villela; Dario Munt de Moraes

    2013-01-01

    The work was conducted to evaluate the effect of different Philodendron bipinnatifidum Schott. extract concentrations on the physiology and enzymatic metabolism of lettuce seeds and seedlings. The treatments extracts of mature leaves at concentrations of 0, 6, 12, 25 and 50%. Were evaluated the germination, first count germination, speed and germination speed index, length of shoot and primary root, seedling total dry mass, electrical conductivity, chlorophyll content, activity of the enzymes...

  19. Allelopathic activity of medicinal plant essential oils on seed germination and vigor of lettuce achenes

    Cíntia Alvarenga Santos Fraga de Miranda

    2015-07-01

    Full Text Available In recent years, essential oils have gained commercial interest in the agricultural area, mainly for their allelopathic, insecticidal, antifungal, antimicrobial and antioxidant properties, and, also for their natural compounds, which have generally displayed low toxicity, relatively low cost and rapid degradation in the environment. Medicinal plants have emerged as potential suppliers of essential oils because of their ethnopharmacological utility. The aim of this study was to evaluate the allelopathic potential of essential oils extracted from fresh leaves of lemon grass (Cymbopogon citratus, wild basil (Ocimum gratissimum L. and sweet basil (Ocimum basilicum L. with regard to their major constituents (citral, eugenol and cineol, respectively in different application forms (direct contact and the effect of volatile constituents on the germination and vigor of lettuce seeds (cultivar Regina SF 3500. The effects of the oils and their major components were evaluated with regard to the variables: first germination count, total germination, GVI (germination velocity index, seedling dry weight and average lengths of shoots and lettuce roots. The essential oils from lemon grass and basil displayed allelopathic potentials on seed germination and vigor of lettuce achenes that can be assigned to their respective major constituents citral and eugenol. On the other hand, the allelopathic effect of the essential oil from basil was a consequence of the combined effect of all the components, regardless the application method.

  20. Tomato chlorotic spot virus in hydroponically-grown lettuce in São Paulo State, Brazil

    Colariccio Addolorata

    2004-01-01

    Full Text Available In the regions of Campinas and Sumaré, São Paulo, Brazil, hidroponically grown crops of Lettuce (Lactuca sativa cv. Verônica, which showed virus-like symptoms were examined by electron microscope, biological, serological and molecular tests. Pleomorphic, enveloped particles (80-100 nm in diameter were always detected in these samples. Experimentally inoculated host plants, including lettuce, reacted with tospoviruses-induced symptoms. Some differences were observed in Gomphrena globosa, which reacted by showing local lesions and systemic mosaic. Two isolates of Tomato chlorotic spot virus (TCSV were identified by DAS-ELISA and by RT-PCR. The sequencing and alignment of the RT-PCR coat protein amplified fragments have indicated a high degree of homology with the TCSV sequences stored in the GenBank. This is the first report of losses due to a virus from the genus Tospovirus in commercial hydroponic lettuce crops in Brazil. Further epidemiological studies are needed for better understanding the spread of the virus in hydroponic crops, since Tomato spotted wilt virus (TSWV is reported to spread through the nutritive solution.

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

    H. R. Roosta

    2010-06-01

    Full Text Available Most plant species are sensitive to high ammonium concentrations. In this experiment the sensitivity of lettuce and spinach to ammonium was investigated. In a factorial experiment with framework of a completely randomized design with two factors, nitrogen form (ammonium and nitrate and plant species (lettuce and spinach, and three replications seeds were germinated in a mixture of perlite, sand and clay in soil-maid pots. After two weeks, the seedlings at two true-leaf stage were then transferred to buckets containing 4 L of aerated nutrient solution. The four plants were growing together. The treatments were ammonium and nitrate at 5 mM. In comparison to nitrate, ammonium reduced the growth of both species. Concentration of K, Mg, and Na decreased with ammonium in both species. The reduction of K and Mg concentrations in ammonium-fed plants may have a role in ammonium toxicity. Ammonium nutrition of both species caused an increase in P at roots and shoots. Higher P content at ammonium-fed lettuce and spinach plants may be due to creation of cations and anions balance in plants. Chlorophyll a and b were higher in ammonium-fed than nitrate-fed plants.

  2. Effect of nickel nutrition on yield, urea accumulation and urease enzyme activity of lettuce

    M. Afyuni

    2011-04-01

    Full Text Available Although nickel (Ni is known as an essential element for higher plants, the biological effects of this nutrient on growth, yield, and N metabolism of some plants, particularly leafy vegetables, is still unknown. Therefore, this study was carried out to investigate the effects of Ni and urea nutrition on the growth and yield of lettuce (Lactuca sativa L. cv. Baker and urea accumulation in plant tissues. In this study, nitrogen was supplied from the source of urea or ammonium nitrate at three levels (5, 10 and 20 mM and Ni was supplied in the form of NiCl2 at two levels (0 and 0.04 µM. The plants were harvested 6 weeks after transplanting and the fresh weight of shoots and roots were determined. The shoots urea concentration and activity of urease enzyme in the leaves were also measured. The results indicated that shoots fresh weight of the urea-fed plants increased with increasing urea concentration in the nutrient solution. Addition of Ni to the nutrient solution significantly promoted the root and shoots fresh weight of urea-fed plants, regardless of N level. Ni nutrition significantly increased the urease activity in the lettuce leaves and as a result, reduced urea accumulation in the shoots and toxicity effects of urea. Therefore, it seems that urea in combination with Ni can successfully be used in production of lettuce in soilless culture systems.

  3. Nutritional disorder of lettuce cv. Veronica in nutrient solution with suppressed macronutrients

    Thiago Batista Firmato de Almeida

    2011-06-01

    Full Text Available Lettuce is the most popular of the leafy vegetables. It is known worldwide and its consumption occurs mainly in the natural form. The objective was to evaluate the effect of macronutrient omission on the growth and nutritional status of the lettuce cv. Veronica, and to describe the visual symptoms of nutritional deficiency. The treatments complete consisted of the solution and the individual omission of N, P, K, Ca, Mg and S, under a completely randomized design with three replications. Plants were grown in Hoagland & Arnon, in pots (8L. At 56 days after transplant we evaluated plant height, leaf number, leaf area, SPAD index, dry matter of shoots, roots and whole plant, levels of macronutrients in shoots and roots, and the nature of nutritional disorders. The omission of nutrients affected the growth variables. The nutrients found in lettuce plants from nutrient solution and the complete omission in the shoot were, respectively, N= 23.2 to 9.5, P= 5.4 to 1.3, K= 58,9 to 3.2, Ca= 12.1 to 3.6, Mg= 5.5 to 0.7 and S= 3.2 to 1.5g.kg-1. The omission of macronutrients caused quality losses, since it affected the nutrition of the vegetables and this resulted in morphological changes, reflected as symptoms of deficiency for each nutrient.

  4. Uptake of azoles by lamb's lettuce (Valerianella locusta L.) grown in hydroponic conditions.

    García-Valcárcel, Ana I; Loureiro, Iñigo; Escorial, Concepción; Molero, Encarnación; Tadeo, José L

    2016-02-01

    An uptake and translocation study of azole compounds was performed in lamb's lettuce (Valerianella locusta L.) grown in nutrient solution fortified with different azoles. Three azoles, (clotrimazole, fluconazole and propiconazole), which have different physico-chemical properties and are ubiquitous in the aquatic environment, were the compounds selected. An analytical method, based on matrix solid phase dispersion (MSPD) followed by LC-MS/MS determination, was developed to quantify these compounds in aqueous solution and in roots and leaves. The physicochemical properties of azoles are the main factors governing the uptake and plant accumulation. These azoles were detected in leaves indicating their transport within lamb's lettuce. Translocation from nutrient solution to the aerial part of lamb's lettuce was found to be highly dependent on the hydrophobicity of the azole. Clotrimazole accumulates in roots causing necrosis in roots and leaves, whereas fluconazole was the azole with the highest concentration in leaves without causing apparent phytotoxicity symptoms. The assessment of the levels of these azoles in leaves indicates that the risk for human health is negligible. PMID:26513529

  5. Pipeline Hydroponic Technology of Lettuce%生菜的管道式水培技术

    刘永红; 何竹青; 李曼; 张军义

    2015-01-01

    管道式水培具有结构简单、投资小、空间利用率高、美观大方等特点。杨凌森禾农业科技有限公司研发使用的生菜管道式水培系统,比传统的水培装置增加了栽培床(管道)的液位控制功能,改善了生菜根系的氧气供应,提高了生菜产量;水培育苗方法简便,成本小,苗床使用面积小,供苗量大,好管理。%Pipeline hydroponics is known of its simple structure ,low investment ,high space utilization ,and elegant appearance . Yangling Senhe Agricultural Technology Co .,Ltd developed a kind of pipeline technology of hydroponic lettuce .The system improved liquid control of pipeline ,roots of lettuce could get more oxygen ,and the yield of lettuce was improved .This technol‐ogy is simple and easy in management .It can produce more seedlings with a smaller seedbed area .

  6. 生菜馒头加工技术研究%Processing Technology of Lettuce Steamed Bread

    韩俊俊; 刘长虹; 何学勇; 李志建; 杨晓露

    2012-01-01

      研究了不同生菜添加量、添加方式及添加时间对馒头感官品质的影响,结果显示,馒头感官品质随生菜添加量的增加呈先升高后降低的趋势,在添加量120 g时馒头品质最佳,而褐变程度则一直增大;添加生菜汁比添加生菜叶取得更好的品质,馒头感官品质随随生菜汁浓度的增大而增大,选取蔬菜汁浓度80%制作馒头较好;二次醒发时生菜的加入时间对馒头品质有一定的影响,二次醒发25 min馒头的品质最优。%  The influence of the different lettuce additive amount,add mode and add time on the sensory quality of steamed bread was studied.The result showed that,with the increasing of the lettuce additive amount,the sensory quality of steamed bread showed a first increases,then decreases trend,and the steamed bread obtained a highest score when the lettuce additive amount is 120 g,while the browning degree showed a downward trend.Add lettuce juice to achieve a better quality than add lettuce,with the increasing of the lettuce juice,the sensory quality of steamed bread showed an upward trend,to select the veg-etable juice concentration 80%,the steamed bread is better.When the secondary leaven,the add time of the lettuce have a cer-tainimpactonthequalityofsteamedbread,andthesteamedbreadobtainedahighestscorewhenthesecondaryleavenis25min.

  7. Hygienic-sanitary quality of vegetables and evaluation of treatments for the elimination of indigenous E. coli and E. coli O157:H7 from the surface of leaves of lettuce (Lactuca sativa L.

    Ytana oliveira Santos

    2010-12-01

    Full Text Available The purpose of this study is to evaluate the hygienic-sanitary quality of vegetables and irrigation water and assess the effectiveness of lemon juice and vinegar in reducing E. coli strains inoculated on lettuce. One hundred and forty samples of vegetables and 45 samples of irrigation water were investigated for thermotolerant coliforms and Salmonella spp. In order to verify the effectiveness of natural household sanitizers in reducing E. coli in inoculated lettuce, four treatment solutions were tested: fresh lemon juice, alcohol vinegar, lemon juice-vinegar mixture, and lemon juice-vinegar-water mixture. The microbiological analysis revealed high rates of contamination by thermotolerant coliforms and identified the presence of E. coli in 32% of the tested vegetable samples and 56% of the water samples. While no significant statistical difference (p < 0, 05 was identified in the tested solutions, the treatment with a combination of lemon juice and vinegar resulted in the highest Decimal Reductions (DR of E. coli O157: H7 while the treatment with vinegar alone was the most effective against the indigenous E. coli strain

  8. Essential oils as biopreservatives: different methods for the technological application in lettuce leaves.

    Ponce, Alejandra; Roura, Sara I; Moreira, María del R

    2011-01-01

    Investigations were carried out to assess the efficiency of 3 essential oils, clove, tea tree, and rosemary, as natural preservatives during the postharvest of lettuce leaves. The effect of different concentration (1 and 0.5 MIC) of plant essential oils applied in 3 forms (spray, immersion, and capsules) was studied on lettuce leaves. The evolution of different microbial populations was evaluated during refrigerated storage. The application forms of the biopreservatives were shown to be an important factor in determining the effectiveness of the essential oils. Clove and tea tree essential oils at 1 MIC and applied embedded in lactose capsules presented a significant inhibition on mesophilic, psicrotrophic, and coliforms populations, while rosemary in none of the 3 technological applications forms exerted inhibitory effect on all microbial populations evaluated. Essential oils (at 0.5 MIC) applied by spray, immersion, and embedded in lactose capsules exerted lower inhibitory effects, with respect to 1 MIC, on the different microbial populations present on lettuce leaves. At the end of the storage (7 d), lettuce samples treated with tea tree, clove, and rosemary (at 1 and 0.5 MIC) by spray were the only organoleptically acceptable. It is concluded that clove and tea tree essential oils can control different microbial population present in lettuce. Practical Application: The exploration of naturally occurring antimicrobials in food preservation receives increasing attention due to consumer awareness of natural food products. Biopreservatives are useful in extending the shelf life of foods, reducing or eliminating pathogenic bacteria and increasing overall quality of food products. The effectiveness of essential oil application in foods is the result of factor associations such as applications forms, concentration applied, the way of action, storage temperatures. The application methods (spray, immersion, and embedded in lactose capsules) and the concentration of

  9. Association mapping and marker-assisted selection of the lettuce dieback resistance gene Tvr1

    Scheffler Brian

    2009-01-01

    Full Text Available Abstract Background Lettuce (Lactuca saliva L. is susceptible to dieback, a soilborne disease caused by two viruses from the family Tombusviridae. Susceptibility to dieback is widespread in romaine and leaf-type lettuce, while modern iceberg cultivars are resistant to this disease. Resistance in iceberg cultivars is conferred by Tvr1 - a single, dominant gene that provides durable resistance. This study describes fine mapping of the resistance gene, analysis of nucleotide polymorphism and linkage disequilibrium in the Tvr1 region, and development of molecular markers for marker-assisted selection. Results A combination of classical linkage mapping and association mapping allowed us to pinpoint the location of the Tvr1 resistance gene on chromosomal linkage group 2. Nine molecular markers, based on expressed sequence tags (EST, were closely linked to Tvr1 in the mapping population, developed from crosses between resistant (Salinas and Salinas 88 and susceptible (Valmaine cultivars. Sequencing of these markers from a set of 68 cultivars revealed a relatively high level of nucleotide polymorphism (θ = 6.7 × 10-3 and extensive linkage disequilibrium (r2 = 0.124 at 8 cM in this region. However, the extent of linkage disequilibrium was affected by population structure and the values were substantially larger when the analysis was performed only for romaine (r2 = 0.247 and crisphead (r2 = 0.345 accessions. The association mapping approach revealed that one of the nine markers (Cntg10192 in the Tvr1 region matched exactly with resistant and susceptible phenotypes when tested on a set of 200 L. sativa accessions from all horticultural types of lettuce. The marker-trait association was also confirmed on two accessions of Lactuca serriola - a wild relative of cultivated lettuce. The combination of three single-nucleotide polymorphisms (SNPs at the Cntg10192 marker identified four haplotypes. Three of the haplotypes were associated with resistance and one

  10. Qualidade de cultivares de alface produzidos em hidroponia Quality of lettuce cultivars grown in hydroponic solution

    Silvana Ohse

    2001-03-01

    Full Text Available O objetivo do presente trabalho foi determinar a composição centesimal de seis cultivares de alface (Aurora, Brisa, Lívia, Mimosa, Regina e Verônica utilizando quatro soluções nutritivas em Santa Maria, RS. Foi utilizado o delineamento experimental inteiramente casualizado com parcelas subdivididas. O experimento constou de oito bancadas, duas para cada solução nutritiva, sendo que cada bancada continha seis canais, um para cada cultivar. O espaçamento utilizado foi 0,18 m entre canais e 0,25 m entre plantas no canal. A solução Ueda, por ter concentração de nutrientes inicial baixa e por essa não ter sido mantida, apresentou maior produção de massa de matéria seca, valor calórico, teores de extrato etéreo e de fibras, depreciando a qualidade do produto final. A alface sob hidroponia (soluções Castellane-Araújo, Furlani e Bernardes é um alimento altamente saudável por manter ou melhorar sua composição centesimal (teores de proteína, extrato etéreo, fibra e resíduo mineral quando comparada com a cultivada no solo, e por ser um produto de baixo valor calórico.The purpose of this research was to define the centesimal composition of six lettuce cultivars (Aurora, Brisa, Lívia, Mimosa, Regina and Verônica using four nutrient solutions. The experimental design was carried out in Santa Maria, RS, Brazil, consisting of entirely randomized subdivided parcels. The used spacing was 0.18 m between array and 0.25 m among plants. It was observed that the Ueda solution should not be used for the lettuce production in NFT system, due to the high dry mass production and, consequently, high caloric value, content of lipids and fibers, depreciating the quality of the final product, in spite of its low nitrate content. The lettuce production in the NFT system using the Castellane-Araújo, Furlani and Bernardes solutions maintained the nutricional quality (protein, ethereal extract and fiber, mineral residue contents equivalent to the

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

    Shrestha, Govinda; Skovgård, Henrik; Steenberg, Tove;

    2015-01-01

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

  12. Effect of biochar amendment on the control of soil sulfonamides, antibiotic-resistant bacteria, and gene enrichment in lettuce tissues.

    Ye, Mao; Sun, Mingming; Feng, Yanfang; Wan, Jinzhong; Xie, Shanni; Tian, Da; Zhao, Yu; Wu, Jun; Hu, Feng; Li, Huixin; Jiang, Xin

    2016-05-15

    Considering the potential threat of vegetables growing in antibiotic-polluted soil with high abundance of antibiotic-resistant genes (ARGs) against human health through the food chain, it is thus urgent to develop novel control technology to ensure vegetable safety. In the present work, pot experiments were conducted in lettuce cultivation to assess the impedance effect of biochar amendment on soil sulfonamides (SAs), antibiotic-resistant bacteria (ARB), and ARG enrichment in lettuce tissues. After 100 days of cultivation, lettuce cultivation with biochar amendment exhibited the greatest soil SA dissipation as well as the significant improvement of lettuce growth indices, with residual soil SAs mainly existing as the tightly bound fraction. Moreover, the SA contents in roots and new/old leaves were reduced by one to two orders of magnitude compared to those without biochar amendment. In addition, isolate counts for SA-resistant bacterial endophytes in old leaves and sul gene abundances in roots and old leaves also decreased significantly after biochar application. However, neither SA resistant bacteria nor sul genes were detected in new leaves. It was the first study to demonstrate that biochar amendment can be a practical strategy to protect lettuce safety growing in SA-polluted soil with rich ARB and ARGs. PMID:26896719

  13. 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

    Delvio Sandri

    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.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 irrigation. 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

  14. Water

    ... www.girlshealth.gov/ Home Nutrition Nutrition basics Water Water Did you know that water makes up more ... to drink more water Other drinks How much water do you need? top Water is very important, ...

  15. Use of Whole Genome Sequencing and Patient Interviews To Link a Case of Sporadic Listeriosis to Consumption of Prepackaged Lettuce.

    Jackson, K A; Stroika, S; Katz, L S; Beal, J; Brandt, E; Nadon, C; Reimer, A; Major, B; Conrad, A; Tarr, C; Jackson, B R; Mody, R K

    2016-05-01

    We report on a case of listeriosis in a patient who probably consumed a prepackaged romaine lettuce-containing product recalled for Listeria monocytogenes contamination. Although definitive epidemiological information demonstrating exposure to the specific recalled product was lacking, the patient reported consumption of a prepackaged romaine lettuce-containing product of either the recalled brand or a different brand. A multinational investigation found that patient and food isolates from the recalled product were indistinguishable by pulsed-field gel electrophoresis and were highly related by whole genome sequencing, differing by four alleles by whole genome multilocus sequence typing and by five high-quality single nucleotide polymorphisms, suggesting a common source. To our knowledge, this is the first time prepackaged lettuce has been identified as a likely source for listeriosis. This investigation highlights the power of whole genome sequencing, as well as the continued need for timely and thorough epidemiological exposure data to identify sources of foodborne infections. PMID:27296429

  16. PERCHLORATE IDENTIFICATION IN FERTILIZERS AND ACCUMULATION IN LETTUCE SEEDLINGS

    Perchlorate has contaminated groundwater, drinking water and soils at several locations in the U.S. The primary source of contamination at sites that have been investigated to date seems to be from industrial and military operations that use Perchlorate as an oxidizing agent. How...

  17. Relationship between Preservation Time of Lettuce and Its Nitrite Content%生菜保存时间与亚硝酸根含量的关系

    詹秀环; 宣亚文; 卢小瑞; 武文

    2009-01-01

    [目的]探明生菜保存时间与亚硝酸根含量的关系.[方法]分别以新鲜和煮熟生莱为材料,采用分光光度法研究不同保存时间生菜的亚硝酸根含量(新鲜生莱每6 h测1次,煮熟生莱每3 h测1次).[结果]在试验周期内,新鲜和煮熟生莱的存放时间越长,其亚硝酸根离子浓度越大,且新鲜生菜中亚硝酸根离子浓度较煮熟生莱中亚硝酸根离子浓度增加的快.[结论]无论是新鲜生菜还是煮熟生菜,均应减少其存放时间.%[Objective] The aim was to prove the relationship between preservation time of lettuce and its nitrite contentt. [Method] With fresh and boiled lettuce as the material, the nitrite content in it was detected by spectrophotometry (fresh lettuce was detected every 6 h and boiled lettuce was detected every 3 h). [Result] In test period, the longer the preservation time of fresh lettuce and boiled lettuce was the higher the nitrite concn. was, and the increasing speed of nitrite concn. in fresh lettuce was faster than that in boiled lettuce. [Conclusion] Whether it was fresh lettuce or boiled lettuce, its preservation time should be decreased.

  18. Freshwater aquatic plant biomass production in Florida

    Reddy, K.R.; Sutton, D.L.; Bowes, G.

    1983-01-01

    About 8% (1.2 million ha) of the total surface area of Florida is occupied by freshwater. Many of these water bodies are eutrophic. Nutrients present in these water bodies can be potentially used to culture aquatic plants as a possible feedstock for methane production. This paper summarizes the results of known research findings on biomass production potential of freshwater aquatic plants in Florida and identifies key research needs to improve the quality and quantity of biomass yields. Among floating aquatic plants, biomass yield potential was in the order of water-hyacinth > water lettuce > pennywort > salvinia > duckweed > azolla. Pennywort, duckweed, and azolla appear to perform well during the cooler months compared to other aquatic plants. Among emergent plants, biomass yield potential was in the order of southern wild rice > cattails > soft rush > bulrush. Cultural techniques, nutrient management, and environmental factors influencing the biomass yields were discussed. 68 references.

  19. Chitin Mixed in Potting Soil Alters Lettuce Growth, the Survival of Zoonotic Bacteria on the Leaves and Associated Rhizosphere Microbiology.

    Debode, Jane; De Tender, Caroline; Soltaninejad, Saman; Van Malderghem, Cinzia; Haegeman, Annelies; Van der Linden, Inge; Cottyn, Bart; Heyndrickx, Marc; Maes, Martine

    2016-01-01

    Chitin is a promising soil amendment for improving soil quality, plant growth, and plant resilience. The objectives of this study were twofold. First, to study the effect of chitin mixed in potting soil on lettuce growth and on the survival of two zoonotic bacterial pathogens, Escherichia coli O157:H7 and Salmonella enterica on the lettuce leaves. Second, to assess the related changes in the microbial lettuce rhizosphere, using phospholipid fatty acid (PLFA) analysis and amplicon sequencing of a bacterial 16S rRNA gene fragment and the fungal ITS2. As a result of chitin addition, lettuce fresh yield weight was significantly increased. S. enterica survival in the lettuce phyllosphere was significantly reduced. The E. coli O157:H7 survival was also lowered, but not significantly. Moreover, significant changes were observed in the bacterial and fungal community of the lettuce rhizosphere. PLFA analysis showed a significant increase in fungal and bacterial biomass. Amplicon sequencing showed no increase in fungal and bacterial biodiversity, but relative abundances of the bacterial phyla Acidobacteria, Verrucomicrobia, Actinobacteria, Bacteroidetes, and Proteobacteria and the fungal phyla Ascomycota, Basidiomycota, and Zygomycota were significantly changed. More specifically, a more than 10-fold increase was observed for operational taxonomic units belonging to the bacterial genera Cellvibrio, Pedobacter, Dyadobacter, and Streptomyces and to the fungal genera Lecanicillium and Mortierella. These genera include several species previously reported to be involved in biocontrol, plant growth promotion, the nitrogen cycle and chitin degradation. These results enhance the understanding of the response of the rhizosphere microbiome to chitin amendment. Moreover, this is the first study to investigate the use of soil amendments to control the survival of S. enterica on plant leaves. PMID:27148242

  20. [The Identification of Lettuce Varieties by Using Unsupervised Possibilistic Fuzzy Learning Vector Quantization and Near Infrared Spectroscopy].

    Wu, Xiao-hong; Cai, Pei-qiang; Wu, Bin; Sun, Jun; Ji, Gang

    2016-03-01

    To solve the noisy sensitivity problem of fuzzy learning vector quantization (FLVQ), unsupervised possibilistic fuzzy learning vector quantization (UPFLVQ) was proposed based on unsupervised possibilistic fuzzy clustering (UPFC). UPFLVQ aimed to use fuzzy membership values and typicality values of UPFC to update the learning rate of learning vector quantization network and cluster centers. UPFLVQ is an unsupervised machine learning algorithm and it can be applied to classify without learning samples. UPFLVQ was used in the identification of lettuce varieties by near infrared spectroscopy (NIS). Short wave and long wave near infrared spectra of three types of lettuces were collected by FieldSpec@3 portable spectrometer in the wave-length range of 350-2 500 nm. When the near infrared spectra were compressed by principal component analysis (PCA), the first three principal components explained 97.50% of the total variance in near infrared spectra. After fuzzy c-means (FCM). clustering was performed for its cluster centers as the initial cluster centers of UPFLVQ, UPFLVQ could classify lettuce varieties with the terminal fuzzy membership values and typicality values. The experimental results showed that UPFLVQ together with NIS provided an effective method of identification of lettuce varieties with advantages such as fast testing, high accuracy rate and non-destructive characteristics. UPFLVQ is a clustering algorithm by combining UPFC and FLVQ, and it need not prepare any learning samples for the identification of lettuce varieties by NIS. UPFLVQ is suitable for linear separable data clustering and it provides a novel method for fast and nondestructive identification of lettuce varieties. PMID:27400511

  1. Proximate, Mineral and Biochemical Evaluation of the Haemolymph of Growing Snails Fed Fresh Lettuce Waste, Whole Lettuce, Pawpaw Leaves and Cabbage Waste

    O.O. Babalola

    2011-01-01

    Full Text Available Disease states in experimental animals are usually accompanied by biochemical alterations. Thus a good working knowledge of reference values of some biochemical constituent of the haemolymph of snails (Archachatina marginata is needed as reference point for future researchers on snail. It is also necessary to determine whether these values could be influenced by diets. Thirty six experimental snails of mean weight of 125.64±2.35g were randomly distributed into 4 dietary treatments of Pawpaw Leaves (PL, Whole Lettuce (WL, Lettuce Wastes (LW and Cabbage Wastes (CW. Nine snails were used as control animals to determine the reference values. They were fed ad libitum for 60 days. Parameters determined were, proximate composition, mineral profile, total protein, albumin, globulin, albumin:globulin, alanine amino transferase (ALT and aspartate amino transferase. There was significant (p<0.05 reduction in crude protein of haemolymph from 24.14 to 21.20% for snails fed LW. The increase in ash from 0.79 to 0.84 in snails fed LW was significant. There were significant increases in all the minerals analyzed in all the treatment groups with Calcium recording the highest concentration of 170 mg/mL. There was also significant (p<0.05 decrease in albumin and albumin:globulin when snails were fed the experimental diets. Values obtained for the enzymes, ALT and AST between treatments were similar. The study established that the feedstuffs were safe for their consumption and could not lead to any tissue damage. Values of 165 unit/l for AST, 11 units/l for ALT, total protein, 7.1 g/dl, globulin, 3.9 g/dl, albumin, 3.2 g/dl, and albumin:globulin, 0.82 could serve as reference values.

  2. Circadian Oscillation of the Lettuce Transcriptome under Constant Light and Light–Dark Conditions

    Higashi, Takanobu; Aoki, Koh; Nagano, Atsushi J.; Honjo, Mie N.; Fukuda, Hirokazu

    2016-01-01

    Although, the circadian clock is a universal biological system in plants and it orchestrates important role of plant production such as photosynthesis, floral induction and growth, there are few such studies on cultivated species. Lettuce is one major cultivated species for both open culture and plant factories and there is little information concerning its circadian clock system. In addition, most of the relevant genes have not been identified. In this study, we detected circadian oscillation in the lettuce transcriptome using time-course RNA sequencing (RNA-Seq) data. Constant light (LL) and light–dark (LD) conditions were used to detect circadian oscillation because the circadian clock has some basic properties: one is self-sustaining oscillation under constant light and another is entrainment to environmental cycles such as light and temperature. In the results, 215 contigs were detected as common oscillating contigs under both LL and LD conditions. The 215 common oscillating contigs included clock gene-like contigs CCA1 (CIRCADIAN CLOCK ASSOCIATED 1)-like, TOC1 (TIMING OF CAB EXPRESSION 1)-like and LHY (LATE ELONGATED HYPOCOTYL)-like, and their expression patterns were similar to those of Arabidopsis. Functional enrichment analysis by GO (gene ontology) Slim and GO Fat showed that the GO terms of response to light stimulus, response to stress, photosynthesis and circadian rhythms were enriched in the 215 common oscillating contigs and these terms were actually regulated by circadian clocks in plants. The 215 common oscillating contigs can be used to evaluate whether the gene expression pattern related to photosynthesis and optical response performs normally in lettuce. PMID:27512400

  3. [Bacteriological quality of traditional, organic and hydroponic cultured lettuce in Costa Rica].

    Monge, Claudio; Chaves, Carolina; Arias, María Laura

    2011-03-01

    The main objective of this work was to evaluate the microbiological quality of lettuces commercialized in the Metropolitan Area of San José, Costa Rica, and cultured in different ways, in order to detect differences between the culturing methods and the risk that these products may represent for Public Health. The study was done at the Food Microbiology Laboratory, Universidad de Costa Rica, from March to July, 2010. 30 lettuce samples were analyzed (10 obtained by traditional culture, 10 by organic culture and 10 by hydropony). All samples were obtained from markets where their origin was certified. Total aerobic plate count, total and fecal coliforms count and Escherichia coli were determined to all samples, as well as the presence/abscense of Salmonella spp. and Listeria monocytogenes in 25 g. Results obtained show that there is no statistically significant difference (p < 0.001) between the different types of cultures analyzed for any of the parameters evaluated. An important percentage of the samples presented coliforms, nevertheless, just one E. coli strain was isolated from a traditionally cultured lettuce sample. Four different Salmonella spp. strains were isolated from the samples as well as one Listeria monocytogenes strain. Data obtained show that the consumption of this product, raw or without an adequate hygiene and disinfection may represent a risk for health. Also, from the bacteriological point of view, there is no significant difference between the culturing methods evaluated, suggesting that the specific directions for each type of culture are not followed or that there is an inadequate handling of the products or post harvest contamination. PMID:22097292

  4. Circadian Oscillation of the Lettuce Transcriptome under Constant Light and Light-Dark Conditions.

    Higashi, Takanobu; Aoki, Koh; Nagano, Atsushi J; Honjo, Mie N; Fukuda, Hirokazu

    2016-01-01

    Although, the circadian clock is a universal biological system in plants and it orchestrates important role of plant production such as photosynthesis, floral induction and growth, there are few such studies on cultivated species. Lettuce is one major cultivated species for both open culture and plant factories and there is little information concerning its circadian clock system. In addition, most of the relevant genes have not been identified. In this study, we detected circadian oscillation in the lettuce transcriptome using time-course RNA sequencing (RNA-Seq) data. Constant light (LL) and light-dark (LD) conditions were used to detect circadian oscillation because the circadian clock has some basic properties: one is self-sustaining oscillation under constant light and another is entrainment to environmental cycles such as light and temperature. In the results, 215 contigs were detected as common oscillating contigs under both LL and LD conditions. The 215 common oscillating contigs included clock gene-like contigs CCA1 (CIRCADIAN CLOCK ASSOCIATED 1)-like, TOC1 (TIMING OF CAB EXPRESSION 1)-like and LHY (LATE ELONGATED HYPOCOTYL)-like, and their expression patterns were similar to those of Arabidopsis. Functional enrichment analysis by GO (gene ontology) Slim and GO Fat showed that the GO terms of response to light stimulus, response to stress, photosynthesis and circadian rhythms were enriched in the 215 common oscillating contigs and these terms were actually regulated by circadian clocks in plants. The 215 common oscillating contigs can be used to evaluate whether the gene expression pattern related to photosynthesis and optical response performs normally in lettuce. PMID:27512400

  5. Production and photosynthetic activity of Mimosa Verde and Mimosa Roxa lettuce in two farming systems

    Aline Mabel Rosa

    2014-08-01

    Full Text Available Lettuce (Lactuca sativa L. is the most commonly consumed leaf vegetable in the Brazilian diet, and it is a good source of vitamins and minerals. It is widely grown in the conventional farming system. However, the hydroponic farming system has been gaining importance in the market, wining confidence from consumers, who are becoming increasingly more demanding on food quality. The objective of this study was to evaluate the performance of two lettuce cultivars on hydroponic and conventional farming systems for the production of fresh mass (FM and dry mass (DM, photosynthesis, contents of chlorophyll and anthocyanin. The following two experiments were carried out: hydroponics farming (HF and conventional farming (CF, performed in protect and unprotect environments, respectively, in Florianópolis, SC. Mimosa Verde cultivar (MV showed greater fresh mass than Mimosa Roxa (MR, in both farming systems and the two cultivars presented better performance in the hydroponic system (287.7 g MV and 139.1 g MR than the conventional system (129.7 g MV and 111.8 g MR. Mimosa Verde cultivar presented lower average contents of total chlorophyll (7.7 mg g-¹ FM than Mimosa Roxa (11.8 mg g-¹FM, and both cultivars displayed higher means for this variable in the hydroponic farming system. Mimosa Roxa presented higher contents of anthocyanin in the conventional system (88.24 mg g-¹ FM than the ones in the hydroponic system (36.89 mg g-¹ FM. The best results for CO2 net assimilation rate regarded to photosyntheticaly active photon flux density were found in the hydroponic system, for both lettuce cultivars. Variation in the contents of chlorophyll were also found. Those variations were higher in the protected system than in the hydroponic system and contents of anthocyanin were higher in the conventional system.

  6. Elucidating the genetic basis of antioxidant status in lettuce (Lactuca sativa).

    Damerum, Annabelle; Selmes, Stacey L; Biggi, Gaia F; Clarkson, Graham Jj; Rothwell, Steve D; Truco, Maria José; Michelmore, Richard W; Hancock, Robert D; Shellcock, Connie; Chapman, Mark A; Taylor, Gail

    2015-01-01

    A diet rich in phytonutrients from fruit and vegetables has been acknowledged to afford protection against a range of human diseases, but many of the most popular vegetables are low in phytonutrients. Wild relatives of crops may contain allelic variation for genes determining the concentrations of these beneficial phytonutrients, and therefore understanding the genetic basis of this variation is important for breeding efforts to enhance nutritional quality. In this study, lettuce recombinant inbred lines, generated from a cross between wild and cultivated lettuce (Lactuca serriola and Lactuca sativa, respectively), were analysed for antioxidant (AO) potential and important phytonutrients including carotenoids, chlorophyll and phenolic compounds. When grown in two environments, 96 quantitative trait loci (QTL) were identified for these nutritional traits: 4 for AO potential, 2 for carotenoid content, 3 for total chlorophyll content and 87 for individual phenolic compounds (two per compound on average). Most often, the L. serriola alleles conferred an increase in total AOs and metabolites. Candidate genes underlying these QTL were identified by BLASTn searches; in several cases, these had functions suggesting involvement in phytonutrient biosynthetic pathways. Analysis of a QTL on linkage group 3, which accounted for >30% of the variation in AO potential, revealed several candidate genes encoding multiple MYB transcription factors which regulate flavonoid biosynthesis and flavanone 3-hydroxylase, an enzyme involved in the biosynthesis of the flavonoids quercetin and kaempferol, which are known to have powerful AO activity. Follow-up quantitative RT-PCR of these candidates revealed that 5 out of 10 genes investigated were significantly differentially expressed between the wild and cultivated parents, providing further evidence of their potential involvement in determining the contrasting phenotypes. These results offer exciting opportunities to improve the nutritional

  7. Root growth and nitrogen uptake of carrot, early cabbage, onion and lettuce following a range of green manures

    Thorup-Kristensen, K.

    2006-01-01

    An experiment was performed to study the significance of rooting depth of four vegetable crops on their utilization of green manure nitrogen (N). Rates of rooting depth development were estimated as approximately 0.2, 0.7, 1.2 and 1.2 mm day C)1 for onion, carrot, lettuce and cabbage, respectively. At harvest, onion and lettuce were found to be shallow-rooted with final rooting depths of only 0.3 and 0.6 m, respectively, whereas carrot and cabbage reached rooting depths of at least 1.1 m. The...

  8. [Antiviral activity of extracts of transgenic cichory and lettuce plants with the human interferon alpha-2b gene].

    Matveeva, N A; Kudriavets, Iu I; Likhova, A A; Shakhovskiĭ, A M; Bezdenezhnykh, N A; Kvasko, E Iu

    2012-01-01

    Biological activity of protein extracts from transgenic plants of chicory Cichorium intybus L. and lettuce Lactuca sativa L. with human interferon alpha2b gene was investigated against vesicular stomatitis virus. It was shown that the extracts from the hairy roots of chicory and lettuce transformed by A. rhizogenes possess the antiviral activity 1620...5400 IU/g weight, and the extracts from leaves of the plants transformed by A. tumefaciens--till 9375 IU/g weight. Dependence of plant extract biological activity on the transformation vector was shown. PMID:23342646

  9. A system and methodology for measuring volatile organic compounds produced by hydroponic lettuce in a controlled environment

    Charron, C. S.; Cantliffe, D. J.; Wheeler, R. M.; Manukian, A.; Heath, R. R.

    1996-01-01

    A system and methodology were developed for the nondestructive qualitative and quantitative analysis of volatile emissions from hydroponically grown 'Waldmann's Green' leaf lettuce (Lactuca sativa L.). Photosynthetic photon flux (PPF), photoperiod, and temperature were automatically controlled and monitored in a growth chamber modified for the collection of plant volatiles. The lipoxygenase pathway products (Z)-3-hexenal, (Z)-3-hexenol, and (Z)-3-hexenyl acetate were emitted by lettuce plants after the transition from the light period to the dark period. The volatile collection system developed in this study enabled measurements of volatiles emitted by intact plants, from planting to harvest, under controlled environmental conditions.

  10. Active packaging for fresh-cut iceberg lettuce (Lactuca sativa L. / Embalagem ativa para alface americana (Lactuca sativa L. minimamente processada

    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

  11. Macroelemental composition of cadmium stressed lettuce plants grown under conditions of intensive sulphur nutrition.

    Matraszek, Renata; Hawrylak-Nowak, Barbara; Chwil, Stanisław; Chwil, Mirosława

    2016-09-15

    Lettuce (Lactuca sativa L.) is moderately sensitive to cadmium (Cd) and shows high accumulation of this metal. Thus, this species is considered to be a good model for both identifying determinants controlling Cd accumulation in plant tissues and for developing breeding strategies aimed at limiting the accumulation of this metal in edible tissues. Simultaneously, lettuce is characterised by medium requirements for sulphur (S) - a macronutrient whose role is associated not only with proper growth and development, but also with stress tolerance. The common use of NPK fertilizers without sulphates (S-SO4) together with the progressive process of reducing emissions of S compounds to the natural environment may lead to deficiency of this element in plants. The present study evaluated the changes in macronutrient content and accumulation in Cd-stressed lettuce 'Justyna' supplied with different S doses. Four concentrations of Cd (0, 0.0002, 0.02 or 0.04 mM) and three levels of S applied in the form of S-SO4 (2, 6 or 9 mM S) were used. Cd exposure impaired the macronutrient balance and accumulation in lettuce. Intensive S nutrition to some extent alleviated Cd-induced toxicity. High S doses, especially 6 mM S, partially improved macronutrient status and restored the macronutrient balance. In Cd-stressed plants supplemented with additional S, an increase in root and shoot biomass and in the content of N, K and Mg was found, without significant changes in the Ca content. Simultaneously, the P and S contents in the biomass of both above- and underground organs remained unchanged. In the leaves, as opposite to the roots, intensive S nutrition reduced the accumulation of Cd. However, the foliar Cd concentration still exceeded the acceptable limits established for consumption. All the obtained results concerning the content of macronutrients and their ratios were referred, inter alia, to the standards i.e. the Diagnosis and Recommendation Integrated System (DRIS) norms. PMID

  12. Uptake of cadmium from phosphate fertilizers by peas, radishes, and lettuce

    Reuss, J.O. (Colorado State Univ., Fort Collins); Dooley, H.L.; Griffis, W.

    1978-01-01

    Cadmium uptake from phosphate fertilizers by radish (Raphanus sativus L.), lettuce (Latuca sativa L.), and garden peas (Pisum sativum L.) was investigated in the greenhouse. Fertilizer in all treatments was applied at the rate of 100 ..mu..g P/g soil to pots containing 4 kg soil. When reagent grade mono-calcium phosphate was used as a P source on a coarse-textured acid soil, Cd contents of edible radish roots and tops were <0.4 ..mu..g/g dry weight; while the Cd content of lettuce, and pea seeds and foliage was <0.2 ..mu..g/g. The use of concentrated superphosphate (CSP) containing 174 ..mu..g Cd/g resulted in plant Cd levels of 2.4, 3.4, 6.3, 0.9, and 0.5 ..mu..g/g for radish roots, radish tops, lettuce, pea seeds and pea foliage, respectively. On a medium-textured calcareous soil the use of this CSP increased the Cd content of radish tops from 0.8 to 1.4 ..mu..g/g, while in lettuce the increase was from 0.8 to 1.2 ..mu..g/g. The effect on radish roots from calcareous soil was nonsignificant. Pea seeds and foliage on this soil were below our Cd detection limit of 0.2 ..mu..g/g. Uptake on both soils was a linear function of the Cd content of the fertilizer. With the acid soil, uptake of Cd from CSP was essentially the same when the fertilizer was placed in a spot 5 cm below the seed as when mixed with the soil. Di-ammonium phosphate (DAP) containing 157 ..mu..g Cd/g resulted in similar uptake to the CSP when mixed with the soil, but spot placement of DAP almost completely eliminated Cd uptake from the fertilizer. In the calcareous soil spot placement increased Cd uptake from the CSP fertilizer but slightly depressed uptake from DAP.

  13. Non-destructive monitoring of agricultural product (lettuce [Lactuca sativa]) based on laser-induced fluorescence

    Quality control of agricultural products in process of cultivation and distribution has become an important problem. This paper describes a field measuring method of lettuce based on laser induced fluorescence (LIF) spectroscopy for growth monitoring. Intensity at 460nm of LIF spectra showed characteristic variations of near harvest time. The results of chemical analysis confirmed that sucrose and chlorogenic acid are origins of the 460nm fluorescence. The prediction of harvest time and the possibility of quality monitoring are discussed based on the experimental data

  14. Fiscalização de hortas produtoras de verduras do município de Ribeirão Preto, SP Monitoring of lettuce crops of Ribeirão Preto, SP, Brazil

    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

  15. Micro-scale elemental partition in tissues of the aquatic plant Lemna minor L. exposed to highway drainage water

    Mendes Godinho, R., E-mail: rmgodinho@yahoo.com [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, EN 10, 2686-953 Sacavém (Portugal); IPMA Instituto Português do Mar e da Atmosfera, Lisboa 1449-006 (Portugal); Raimundo, J.; Vale, C.; Anes, B.; Brito, P. [IPMA Instituto Português do Mar e da Atmosfera, Lisboa 1449-006 (Portugal); Alves, L.C.; Pinheiro, T. [IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, EN 10, 2686-953 Sacavém (Portugal); CFNUL – Centro de Física Nuclear da Universidade de Lisboa (Portugal)

    2013-07-01

    In the scope of a monitoring program to assess the environmental impact of automobile traffic over one main bridge in Lisbon, both water and duckweed (Lemna minor L.) were sampled from the road drainage tanks and analyzed for chemical elements. Plants uptake Cr, Mn, Cu, and Zn metals from rain water draining the bridge road. Nuclear microprobe elemental maps of cryosections of L. minor tissues showed that incorporated elements were internalized in fronds of the plant. This approach at micrometer level allows a better knowledge of the elemental tissue partitioning in this biomonitor organism.

  16. Manejo de irrigação para cultivo de alface em ambiente protegido Irrigation management for growing lettuce in greenhouse

    George RL Bandeira

    2011-06-01

    Full Text Available A determinação do consumo de água de irrigação é fundamental para o manejo correto dos cultivos irrigados. Este trabalho teve o objetivo de estudar o desenvolvimento de duas cultivares da alface (AF 1743 e OGR 326, em ambiente protegido, no município de Juazeiro-BA, sob dois métodos de manejos de irrigação: reposição de água de irrigação determinada por tensiometria (M1 e reposição de água determinada na evaporação de água de tanque reduzido (M2, instalados em ambiente protegido. Observou-se efeito de interação entre os tratamentos impostos e as cultivares de alface estudadas, para a massa fresca das raízes das plantas. O uso da tensiometria promoveu desempenho superior para as variáveis de produção analisadas, como observado na massa fresca da parte aérea, apresentando média geral de 145,0 g, enquanto no manejo M2 tal valor foi de 59,4 g. Dentre as cultivares analisadas para referida variável, observou-se um resultado superior para a cultivar OGR 326 quando comparada à AF 1743.The determination of the water consumption is fundamental for the correct management of irrigated crops. The development of two lettuce cultivars (AF 1743 and OGR 326 was determined, when cultivated in a protected environment under two irrigation management methods: water consumption determined by the tensiometry (M1 and water consumption determined by evaporation of water in the reduced pan (M2, which were installed inside the protected environment. There was significant interaction among the imposed treatment and the cultivars of lettuce studied, for the fresh weight of the roots of the plants. The use of tensiometry promoted superior performance for the analyzed production variables as observed in the fresh weight of the aboveground part, with an overall average of 145.0 g, whereas for the management M2 the overall average was 59.4 g. For this variable, among the cultivars a superior result was obtained for the cultivar OGR 326 in

  17. Effects of poultry litter biochar on soil enzyme activities and tomato, pepper and lettuce plants growth

    Muhittin Onur Akça

    2015-07-01

    Full Text Available Biochar application to soils is being considered as a means to sequester carbon (C while concurrently improving soil functions. A greenhouse experiment was carried out to determine the effects of biochar from the pyrolysis poultry litter (PL on the soil enzyme activities, organic matter content and growth of tomato, pepper and lettuce plants. In the experiment, the combination of 15.15.15 composite fertilizer with 0, 200, 400 and 600kg/da doses of PL biochar were applied into the clay loam soil. Compared to the control and chemical fertilizer alone, the soil organic matter was significantly increased after biochar amendments. β-glucosidase, alkaline phosphatase, urease and arylsulphatase enzyme activities in soils were increased by the biochar applications significantly (P<0.05. Plant fresh and dry weight of tomato, pepper and lettuce plants were higher in 4kg/ha PL biochar treatment than in the other treatments. The results showed that PL biochar amendment to soils in the agricultural use increased yield of plants and enzyme activities with increasing soil organic matter content as well as improving soil properties.

  18. Lettuce genotype resistance to "soft rot" caused by Pectobacterium carotovorum subsp. carotovorum

    Kátia Cilene da Silva Felix

    2014-08-01

    Full Text Available Soft rot, caused by Pectobacterium carotovorum subsp. carotovorum (Pcc, is the main bacterial disease affecting lettuce (Lactuca sativa L. crops in Brazil and leads to significant yield losses. This study aimed to assess the reaction of lettuce genotypes to soft rot induced by a virulent isolate and the stability of the resistance to three isolates varying in virulence. Using a descriptive ordinal scale ranging from 1 to 9 a classification system was defined: class 1 = resistant (R: severity (Sev 3.5. Of the 41 tested genotypes, 14 were classified as MR and 27 as S when inoculated with a Pcc isolate of intermediate virulence. Eleven of these genotypes (four S and seven MR were selected to test their resistance stability against three other isolates with an increasing degree of virulence (Pcc36 < Pcc-A1.1 < Pcc-23. Out of the 11 genotypes eight retained the original classification and three moved from S to MR resistant class when challenged with the least virulent isolate. Vitória de Santo Antão was the only genotype classified as MR for all tested isolates and is a promising candidate for durable soft rot resistance breeding.

  19. On hybridising lettuce seedlings with nanoparticles and the resultant effects on the organisms' electrical characteristics.

    Gizzie, Nina; Mayne, Richard; Patton, David; Kendrick, Paul; Adamatzky, Andrew

    2016-09-01

    Lettuce seedlings are attracting interest in the computing world due to their capacity to become hybrid circuit components, more specifically, in the creation of living 'wires'. Previous studies have shown that seedlings can be hybridised with gold nanoparticles and withstand mild electrical currents. In this study, lettuce seedlings were hybridised with a variety of metallic and non-metallic nanomaterials: carbon nanotubes, graphene oxide, aluminium oxide and calcium phosphate. Toxic effects and the following electrical properties were monitored: mean potential, resistance and capacitance. Macroscopic observations revealed only slight deleterious health effects after administration with one variety of particle, aluminium oxide. Mean potential in calcium phosphate-hybridised seedlings showed a considerable increase when compared with the control, whereas those administered with graphene oxide showed a small decrease; there were no notable variations across the remaining treatments. Electrical resistance decreased substantially in graphene oxide-treated seedlings whereas slight increases were shown following calcium phosphate and carbon nanotubes applications. Capacitance showed no considerable variation across treated seedlings. These results demonstrate that use of some nanomaterials, specifically graphene oxide and calcium phosphate, may be towards biohybridisation purposes including the generation of living 'wires'. PMID:27424022

  20. Exploring the limits of crop productivity: beyond the limits of tipburn in lettuce

    Frantz, Jonathan M.; Ritchie, Glen; Cometti, Nilton N.; Robinson, Justin; Bugbee, Bruce

    2004-01-01

    The productivity of lettuce in a combination of high light, high temperature, and elevated CO2 has not been commonly studied because rapid growth usually causes a calcium deficiency in meristems called tipburn, which greatly reduces quality and marketability. We eliminated tipburn by blowing air directly onto the meristem, which allowed us to increase the photosynthetic photon flux (PPF) to 1000 micromoles m-2 s-1 (57.6 mol m-2 d-1); two to three times higher than normally used for lettuce. Eliminating tipburn doubled edible yield at the highest PPF level. In addition to high PPF, CO2 was elevated to 1200 micromoles m-2 mol-1, which increased the temperature optimum from 25 to 30 degrees C. The higher temperature increased leaf expansion rate, which improved radiation capture and more than doubled yield. Photosynthetic efficiency, measured as canopy quantum yield in a whole-plant gas exchange system, steadily increased up to the highest temperature of 32 degrees C in high CO2. The highest productivity was 19 g m-2 d-1 of dry biomass (380 g d-1 fresh mass) averaged over the 23 days the plants received light. Without the limitation of tipburn, the combination of high PPF, high temperature, and elevated CO2 resulted in a 4-fold increase in growth rate over productivity in conventional environments.

  1. Changes in hyperspectral reflectance signatures of lettuce leaves in response to macronutrient deficiencies

    Pacumbaba, R. O.; Beyl, C. A.

    2011-07-01

    The adaptation of specific remote sensing and hyperspectral analysis techniques for the determination of incipient nutrient stress in plants could allow early detection and precision supplementation for remediation, important considerations for minimizing mass of advanced life support systems on space station and long term missions. This experiment was conducted to determine if hyperspectral reflectance could be used to detect nutrient stress in Lactuca sativa L. cv. Black Seeded Simpson. Lettuce seedlings were grown for 90 days in a greenhouse or growth chamber in vermiculite containing modified Hoagland's nutrient solution with key macronutrient elements removed in order to induce a range of nutrient stresses, including nitrogen, phosphorus, potassium, calcium, and magnesium. Leaf tissue nutrient concentrations were compared with corresponding spectral reflectances taken at the end of 90 days. Spectral reflectances varied with growing location, position on the leaf, and nutrient deficiency treatment. Spectral responses of lettuce leaves under macronutrient deficiency conditions showed an increase in reflectance in the red, near red, and infrared wavelength ranges. The data obtained suggest that spectral reflectance shows the potential as a diagnostic tool in predicting nutrient deficiencies in general. Overlapping of spectral signatures makes the use of wavelengths of narrow bandwidths or individual bands for the discrimination of specific nutrient stresses difficult without further data processing.

  2. Host Genotype and Hypersensitive Reaction Influence Population Levels of Xanthomonas campestris pv. vitians in Lettuce.

    Bull, Carolee T; Gebben, Samantha J; Goldman, Polly H; Trent, Mark; Hayes, Ryan J

    2015-03-01

    Dynamics of population sizes of Xanthomonas campestris pv. vitians inoculated onto or into lettuce leaves were monitored on susceptible and resistant cultivars. In general, population growth was greater for susceptible (Clemente, Salinas 88, Vista Verde) than resistant (Batavia Reine des Glaces, Iceberg, Little Gem) cultivars. When spray-inoculated or infiltrated, population levels of X. campestris pv. vitians were consistently significantly lower on Little Gem than on susceptible cultivars, while differences in the other resistant cultivars were not consistently statistically significant. Populations increased at an intermediate rate on cultivars Iceberg and Batavia Reine des Glaces. There were significant positive correlations between bacterial concentration applied and disease severity for all cultivars, but bacterial titer had a significantly greater influence on disease severity in the susceptible cultivars than in Little Gem and an intermediate influence in Iceberg and Batavia Reine des Glaces. Infiltration of X. campestris pv. vitians strains into leaves of Little Gem resulted in an incompatible reaction, whereas compatible reactions were observed in all other cultivars. It appears that the differences in the relationship between population dynamics for Little Gem and the other cultivars tested were due to the hypersensitive response in cultivar Little Gem. These findings have implications for disease management and lettuce breeding because X. campestris pv. vitians interacts differently with cultivars that differ for resistance mechanisms. PMID:25302523

  3. Natural Radionuclides Intake into Soya, Corn and Lettuce Grown on Soil Amended with Phosphogypsum

    Phosphogypsum is a by-product of the phosphate fertilizers industry and is produced by precipitation during wet process of phosphate rocks, thus posing serious problems with its utilization and safe disposal. In Brazil, three main industries are responsible for the production and storage of about 5.5x106 tons per year. PG may contain radionuclides of U and Th series. The main objective of this study is to evaluate the environmental impact of the use of phosphogypsum as soil amendment by evaluating the radionuclides transfer in the soil/plant system. To accomplish this task an experiment was carried out in green house, where two major crop groups ( soya and corn ) and leafy vegetable (lettuce) were grown in two types of soil ( clay and sandy ) amended with phosphogypsum. The radionuclides 226Ra, 228Ra and 210Pb were determined by a radiochemical procedure and by gamma spectrometry. 210Po was spontaneously plated on a silver disc and measured by alpha spectrometry. Activity concentrations of 238U and 232Th in soil, phosphogypsum, crops and lettuce were determined by using instrumental neutron activation analysis (INAA). The transfer-factors were evaluated for all the radionuclides analyzed. (author)

  4. Biotic stress shifted structure and abundance of Enterobacteriaceae in the lettuce microbiome.

    Armin Erlacher

    Full Text Available Lettuce cultivars are not only amongst the most popular vegetables eaten raw, they are also involved in severe pathogen outbreaks world-wide. While outbreaks caused by Enterobacteriaceae species are well-studied, less is known about their occurrence in natural environments as well as the impact of biotic stress. Here, we studied the ecology of the human health-relevant bacterial family Enterobacteriaceae and assessed the impact of biotic disturbances by a soil-borne phytopathogenic fungus and Gastropoda on their structure and abundance in mesocosm and pot experiments. Using a polyphasic approach including network analyses of 16S rRNA gene amplicon libraries, quantitative PCR and complementary fluorescence in situ hybridization (FISH microscopy we found substantial yet divergent Enterobacteriaceae communities. A similar spectrum of 14 genera was identified from rhizo- and phyllospheres but the abundance of Enterobacteriaceae was on average 3fold higher in phyllosphere samples. Both stress factors shifted the bacterial community of the leaf habitat, characterized by increases of species abundance and diversity. For the rhizosphere, we observed significant structural shifts of Enterobacteriaceae communities but also a high degree of resilience. These results could be confirmed by FISH microscopy but it was difficult to visualize phyllosphere communities. Additional inoculation experiments with Escherichia coli as model revealed their presence below the wax layer as well as in the endosphere of leaves. The observed presence influenced by stress factors and the endophytic life style of Enterobacteriaceae on lettuce can be an important aspect in relation to human health.

  5. Prediction of rate of CO2 assimilation of leaf lettuce under low light irradiation during storage

    The rate of CO2 assimilation of leaf lettuce changed with its respiration rate and gas constitution in a storage chamber. The optimum irradiance on the surface of leaf lettuce during storage using low light irradiation can be obtained by the prediction of the rate of CO2 assimilation. For the above mentioned purpose the following equation were derived. -kd[C]/dt=0.5(1-f)I([C]-Γ/4.5[C]+10.5Γ)-ae-bt where, k: proportional constant (4.87×10-3mol⋅m-2) [C]: CO2 concentration (ppm), t: time (h), f: fraction of light not absorbed by chloroplasts (0.23), I: irradiance (μmol⋅m-2⋅s-1), Γ: CO2 compensation point without respiration (21.5ppm), a, b: parameters (0.308μmol⋅m-2⋅s-1, 0.010h-1). Calculated values of rate of CO2 assimilation by the equation agreed well with experimental ones at 3.4 and 6.5μmol⋅m-2⋅s-1 of irradiance, so it appeared that the assimilation rate could be sufficiently predicted

  6. Application of artificial neural networks in indirect selection: a case study on the breeding of lettuce

    Alcinei Mistico Azevedo

    2015-12-01

    Full Text Available The efficiency of artificial neural networks (ANN to model complex problems may enable the prediction of characteristics that are hard to measure, providing better results than the traditional indirect selection. Thus, this study aimed to investigate the potential of using artificial neural networks (ANN for indirect selection against early flowering in lettuce, identify the influence of genotype by environment interaction in this strategy and compare your results with the traditional indirect selection. The number of days to anthesis were used as the desired output and the information of six characteristics (fresh weight of shoots, mass of marketable fresh matter of shoots, commercial dry matter of shoots, average diameter of the head, head circumference and leaf number as input file for the training of the ANN-MLP (Perceptron Multi-Layer. The use of ANN has great potential adjustment for indirect selection for genetic improvement of lettuce against early flowering. The selection based on the predicted values by network provided estimates of gain selection largest that traditional indirect selection. The ANN trained with data from an experiment have low power extrapolation to another experiment, due to effect of interaction genotype by environment. The ANNs trained simultaneously with data from different experiments presented greater predictive power and extrapolation.

  7. Physiological responses of seeds and seedlings of lettuce submitted to Philodendron bipinnatifidum extract

    Tiago Zanatta Aumonde

    2013-12-01

    Full Text Available The work was conducted to evaluate the effect of different Philodendron bipinnatifidum Schott. extract concentrations on the physiology and enzymatic metabolism of lettuce seeds and seedlings. The treatments extracts of mature leaves at concentrations of 0, 6, 12, 25 and 50%. Were evaluated the germination, first count germination, speed and germination speed index, length of shoot and primary root, seedling total dry mass, electrical conductivity, chlorophyll content, activity of the enzymes ?-amilase, superoxide dismutase, catalase and ascorbarto peroxidase, lipid peroxidation, hydrogen peroxide content and seedling emergence, length of shoot and total dry mass of emerged seedlings. There was a reduction of germination, germination speed index and total dry mass by increasing the concentration of the extract. While the content of hydrogen peroxide, lipid peroxidation and activity of superoxide dismutase, catalase and peroxidase ascorbarto increased with concentration. The increasing of concentration the leaf extracts of the P. bipinnatifidum negatively affects the activity of the enzyme ?-amylase and causes increase in the activity of antioxidant enzymes, affecting the physiologic performance and growth of lettuce seedlings.

  8. Effects of irradiation on the sensory characteristics of vegetables (celery, lettuces and cabbage)

    In the last few years, irradiation has been applied to a growing number of food products in order to increase their conservation process. This technology has to be informed to consumers in order to get their acceptation. The object of this research was to irradiate three kinds of vegetables, Celery, Lettuce and Cabbage with 0.50; 0.75 and 1.00 kGy doses and subject them to a sensorial analysis to measure their acceptability and quality. The parameters considered in the analysis of the products were color, smell, sweetness, sour taste, texture, bitterness, and flavor. As well in quality as in acceptability we used a structured value scale from 1 to 9 points, the results were processed statistically by the analyses of Varianza and Duncan test of multiple range in a level of 5% significance. The analyzed data proved that Cabbage was the most resistant to the irradiation treatment. On the other hand we just observed a significant differences in appearances in Lettuce and in color in Celery, which faded on the sixth day. In general terms we can sustain that products showed good acceptability in our control samples and also in the irradiated ones, until the sixth day after their harvest. (au)

  9. Effect of phenol on germination capacity and polyphenol oxidase, peroxidase and catalase activities in lettuce

    Tadić Vojin

    2014-01-01

    Full Text Available In this study we examined the activities of polyphenol oxidase (PPO and antioxidant enzymes, peroxidase (POX and catalase (CAT during lettuce seed germination at different concentrations of phenol. Out of eleven varieties of lettuce, four were chosen according to their germination tolerance to phenol as follows: plants exhibiting high (Ljubljanska ledenka - LJL and Nansen - N and low toleranace (Little Gem - LG and Majska kraljica - MK. A decrease in germination efficiency after exposure to LD50 of phenol was determined for these four varieties. The effects of phenol treatment on POX, CAT and PPO activities were determined after 4, 5, 6, 7 and 8 days of growth at LD50 concentrations. A trend of increased peroxidase activity was observed in seeds grown on LD50 of phenol compared to control seeds. A significant increase in CAT activity was observed at the beginning of treatment for MK, LG and N in seeds grown on phenol as well as in control seeds. A trend of increased PPO activity was observed in all control seeds. We also investigated the affinity of PPO for two different substrates that were used for the determination of enzyme activity. Our results show that LJL and N are the varieties most tolerant to growth on phenol. Here we report on the activities of their antioxidant enzymes and PPO during seed germination. [Projekat Ministarstva nauke Republike Srbije, br. ON173017

  10. Retrospectiva e tendência da alfacicultura brasileira Retrospective and trends of Brazilian lettuce crop

    Fernando Cesar Sala

    2012-06-01

    Full Text Available A alface é considerada a principal hortaliça folhosa no Brasil. Nas ultimas décadas, houve muitas mudanças quanto aos tipos varietais predominantes no país bem como para a preferência do uso de semente peletizada. O domínio do cultivo da alface lisa foi até a década de 90 com as cultivares do tipo 'manteiga' e 'Regina'. Posteriormente, houve uma mudança para o tipo crespa e que, atualmente, corresponde ao principal segmento cultivado no Brasil. A ausência de formação de cabeça aliada à presença de folhas flabeladas conferiram a esse tipo de alface uma melhor adaptação no cultivo de verão com altas temperaturas e índices de pluviosidade. A preferência brasileira pela alface crespa é um fato único na alfacicultura mundial. A alface americana vem apresentando maiores índices de crescimento e aceitação pelo mercado consumidor. Apesar de apresentar formação de cabeça e que tem limitado seu cultivo no verão, na ausência de cultivo protegido, suas folhas mais espessas têm conferido melhor sabor, crocância e durabilidade pós-colheita na alface americana. Alface com folha espessa é mandatória para o mercado de processamento que apresenta alta tendência de crescimento. Considerações sobre o melhoramento genético para contribuir, pelo menos em parte, com essa situação são discutidas com o surgimento de novos tipos varietais tropicalizados, com a tendência de segmentação de mercado e da necessidade de uma cadeia pós-colheita mais eficiente.Lettuce is considered the main leafy vegetable crop in Brazil. In recent decades, many changes occurred towards the varietal types as well as in the preference for pelleted seeds. Until mid 90 decade, the dominant varieties of looseleaf lettuce were the type 'White Boston' and 'Regina'. Later, there was a change toward the Grand Rapids type which represents the main varietal segment grown in Brazil. The non-head Grand Rapids type with its earliness performed better adaptation

  11. Resistance to downy mildew in lettuce ‘La Brillante’ is conferred by dm50 gene and multiple QTL

    Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar La Brillante has a high level of field resistance to the disease in California. Testing of a mapping popu...

  12. Metagenomic analysis of viruses associated with field-grown and retail lettuce identifies human and animal viruses.

    Aw, Tiong Gim; Wengert, Samantha; Rose, Joan B

    2016-04-16

    The emergence of culture- and sequence-independent metagenomic methods has not only provided great insight into the microbial community structure in a wide range of clinical and environmental samples but has also proven to be powerful tools for pathogen detection. Recent studies of the food microbiome have revealed the vast genetic diversity of bacteria associated with fresh produce. However, no work has been done to apply metagenomic methods to tackle viruses associated with fresh produce for addressing food safety. Thus, there is a little knowledge about the presence and diversity of viruses associated with fresh produce from farm-to-fork. To address this knowledge gap, we assessed viruses on commercial romaine and iceberg lettuces in fields and a produce distribution center using a shotgun metagenomic sequencing targeting both RNA and DNA viruses. Commercial lettuce harbors an immense assemblage of viruses that infect a wide range of hosts. As expected, plant pathogenic viruses dominated these communities. Sequences of rotaviruses and picobirnaviruses were also identified in both field-harvest and retail lettuce samples, suggesting an emerging foodborne transmission threat that has yet to be fully recognized. The identification of human and animal viruses in lettuce samples in the field emphasizes the importance of preventing viral contamination on leafy greens starting at the field. Although there are still some inherent experimental and bioinformatics challenges in applying viral metagenomic approaches for food safety testing, this work will facilitate further application of this unprecedented deep sequencing method to food samples. PMID:26894328

  13. Green leaf lettuce breeding lines with resistance to corky root, 06-831 and 06-833.

    The Agricultural Research Service, United States Department of Agriculture (USDA) announces the release of two breeding lines of green leaf lettuce (Lactuca sativa L.). The lines 06-831 and 06-833 look similar to ‘Waldmann’s Green’ and related cultivars. The lines may be suitable for commercial pro...

  14. Biocontrol of Escherichia coli O157:H7 on fresh-cut lettuce and cantaloupe by treatment with bacteriophage

    Introduction: Outbreaks of foodborne illness have been associated with the consumption of cantaloupes and fresh-cut lettuce. Bacteriophage mixtures may be effective biocontrol agents to reduce E. coli O157:H7 on produce. Purpose: The effectiveness of a mixture of bacteriophages (ECP-100) in reducin...

  15. Quantification of contamination of lettuce by GFP-expressing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium

    Franz, Eelco; Visser, Anna A; Van Diepeningen, Anne D; Klerks, Michel M; Termorshuizen, Aad J; van Bruggen, Ariena H C

    2007-01-01

    The primary objective of this study was to determine the possibility of internalization of GFP-expressing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium (S. Typhimurium) strains MAE 110 (multi-cellular morphology) and 119 (wild type morphology) into lettuce seedlings (Lactuca s

  16. Pure phosphine fumigation treatment at low temperature for postharvest control of western flower thrips on lettuce, broccoli, asparagus, and strawberries

    U.S. exported lettuce, broccoli, asparagus, and strawberries often harbor western flower thrips (Frankliniella occidentalis), a quarantined pest in Taiwan, and therefore require quarantine treatment. Pure phosphine fumigation at a low temperature of 2°C was studied as an alternative fumigant to meth...

  17. Analysis of bacteria, parasites, and heavy metals in lettuce (Lactuca sativa) and rocket salad (Eruca sativa L.) irrigated with treated effluent from a biological wastewater treatment plant.

    Nikaido, Meire; Tonani, Karina A A; Julião, Fabiana C; Trevilato, Tânia M B; Takayanagui, Angela M M; Sanches, Sérgio M; Domingo, José L; Segura-Muñoz, Susana I

    2010-06-01

    This study aimed to evaluate the viability of using treated residuary water from the Biological Wastewater Treatment Plant of Ribeirão Preto to grow vegetables, through the characterization and quantification of parasites, coliforms, and heavy metals. Three equal cultivation areas were prepared. The first was irrigated with treated/chlorinated (0.2 mg L(-1)) wastewater, the second one with treated wastewater without chlorination, and the third site with potable water, which was the control group. The presence of Hymenolepis nana, Enterobius vermicularis, nematode larvae, and Entamoeba coli was verified in lettuce (Lactuca sativa) samples. Although nematode larvae were observed in rocket salad (Eruca sativa L.), no significant differences were found between the number of parasites and type of irrigation water used. No significant differences were found between the number of fecal coliforms in vegetables and the different types of irrigation. However, the vegetables irrigated with treated effluent without chlorination showed higher levels of fecal coliforms. The risk of pathogens is reduced with bleach addition to the treated effluent at 0.2 mg/L. Concentration of heavy metals in vegetables does not mean significant risks to human health, according with the parameters recommended by the World Health Organization. PMID:19639268

  18. Changes in soil chemical properties and lettuce yield response following incorporation of biochar and cow dung to highly weathered acidic soils

    Agyei Frimpong, Kwame; Amoakwah, Emmanuel; Osei, Benjamin;

    2016-01-01

    imposed on two highly weathered, acidic soils from the coastal savanna and tropical rainforest agroecological zones of Ghana, respectively, to elucidate their effect on yield of lettuce. The study showed that application of biochar solely or in combination with cow dung increased soil pH, total organic...... carbon, and cation exchange capacity, and temporarily increased soil respiration and microbial biomass carbon. Further, incorporation of combined application of cow dung and biochar increased lettuce yield more than sole incorporation of either amendment. The study demonstrated that corn cob biochar can...... improve soil chemical properties and lettuce yield if applied solely or in combination with cow dung....

  19. Land spreading of sewage sludge in forest plantations: effects on the growth of the duckweed Lemna minor and trace metal bioaccumulation in the snail Cantareus aspersus.

    Mohamed, Bourioug; Frédéric, Gimbert; Laurence, Alaoui-Sehmer; Pierre-Marie, Badot; Badr, Alaoui-Sossé; Lotfi, Aleya

    2016-05-01

    Wastewater plants generated annually millions of tons of sewage sludge (SS). Large amounts of this organic residue are spread on agricultural lands as a fertilizer, although it is viewed as a major potential source of contamination, presenting a danger to the terrestrial and aquatic environments. This study was undertaken to evaluate the impact of this practice on the duckweed Lemna minor and the snail Cantareus aspersus. Sludge was applied to soil either at six different loading rates equal to 0, 0.4, 3, 10, 30, and 60 tons dry matter (DM) ha(-1) for L. minor test or at three rates equal to 0, 30, and 60 tons DM ha(-1) for C. aspersus test. At the highest rate of SS application (60 tons DM ha(-1)), the eluates showed that an increase in pH (6.1) resulted in a decrease in Al levels. Thus, the high stimulation of L. minor growth observed after this high rate of SS application can be explained by (i) a reduction in Al toxicity after precipitation and (ii) macro- and micronutrient enrichment. At a rate of SS application of only 30 tons DM ha(-1), growth appeared to be slightly significant (p < 0.05), in spite of the significant increase in essential mineral elements. However, it is very difficult to discriminate between Al toxicity and pH effects. For the test with C. aspersus, the snail biomass was not affected by sludge application over the exposure period. Mortality was extremely low, with a rate of less than 4 % at the last sampling date. Yet, Cu, Pb, and Cd accumulated significantly in the soft body of snails exposed to SS application, suggesting that the amount of metals excreted is lower than that absorbed. In contrast, Zn levels remain constant, inferring that absorption and elimination of Zn are balanced at the beginning of the experiment. PMID:26856869

  20. Reasoned opinion on the modification of the existing MRLs for azoxystrobin in lettuce, spinach, celery, cardoon, spices and rhubarb

    European Food Safety Authority

    2012-11-01

    Full Text Available In accordance with Article 6 of Regulation (EC No 396/2005, France received an application from the company Syngenta Agro SAS to modify the existing MRLs for the active substance azoxystrobin in lettuce, spinach, celery and cardoon. In order to accommodate for the intended use of azoxystrobin, France proposed to raise the existing MRLs to 15 mg/kg for spinach and similar, lettuces and other salad plants, celery and cardoon. Germany received an application from the plant protection service Landesamt für Landwirtschaft, Forsten und Gartenbau des Landes Sachesen-Anhalt to modify the existing MRLs for the active substance azoxystrobin in spices. In order to accommodate for the intended use Germany proposed to raise the existing MRLs to 0.3 mg/kg for spices/seeds and spices/fruits and berries. Belgium compiled an application to modify the existing MRL for the azoxystrobin in rhubarb. In order to accommodate for the intended use Belgium proposed to raise the existing MRLs to 0.5 mg/kg. France, Germany and Belgium drafted an evaluation report according to Article 8 of Regulation (EC No 396/2005, which was submitted to the European Commission and forwarded to EFSA. According to EFSA the data are sufficient to derive MRL proposals for lettuce, spinach and similar, cardoon, celery, rhubarb and spices. For other crops belonging to the group of lettuce and other salad plants the data were not sufficient to propose a MRL. Adequate analytical enforcement methods are available to control the residues of azoxystrobin on the commodities under consideration at the validated LOQ of 0.01 mg/kg. Based on the risk assessment results, EFSA concludes that the proposed use of azoxystrobin on lettuce, spinach, celery, cardoon, spices and rhubarb will not result in a consumer exposure exceeding the toxicological reference values and therefore is unlikely to pose a consumer health risk.

  1. Effects of illuminants and illumination time on lettuce growth, yield and nutritional quality in a controlled environment

    Shen, Y. Z.; Guo, S. S.; Ai, W. D.; Tang, Y. K.

    2014-07-01

    Effects of illuminants and illumination time on the growth of lettuce were researched. Red-blue light-emitting diodes (LEDs, 90% red light +10% blue light) and white light fluorescent (WF) lamps were compared as the illuminants for plant cultivation. Under each type of illuminant, lettuce was grown at 4 illumination times: 12 h, 16 h, 20 h and 24 h, with the same light intensity of 600 μmolm-2s-1. The leaf net photosynthetic rate (Pn) under the two illuminants was comparable but the shape of lettuce was obviously affected by the illuminant. The WF lamps produced more compact plant, while red-blue LED resulted in less but longer leaves. However, the total leaf area was not significantly affected by the illuminant. The red-blue LED produced nearly same aboveground biomass with far less energy consumption relative to WF lamps. The underground biomass was lowered under red-blue LED in comparison with WF lamps. Red-blue LED could improve the nutritional quality of lettuce by increasing the concentration of soluble sugar and vitamin C (VC) and reducing the concentration of nitrate. Under each type of illuminant, longer illumination time resulted in higher Pn, more leaves and larger leaf area. The total chlorophyll concentration increased while the concentration ratio of chlorophyll a/b decreased with the extension of illumination time. Illumination time had highly significant positive correlation with biomass. Moreover, when total daily light input was kept the same, longer illumination time increased the biomass significantly as well. In addition, longer illumination time increased the concentration of crude fiber, soluble sugar and VC and reduced the concentration of nitrate. In summary, red-blue LEDs and 24 h illumination time were demonstrated to be more suitable for lettuce cultivation in the controlled environment.

  2. Effectiveness of Active Packaging on Control of Escherichia Coli O157:H7 and Total Aerobic Bacteria on Iceberg Lettuce.

    Lu, Haixia; Zhu, Junli; Li, Jianrong; Chen, Jinru

    2015-06-01

    Contaminated leafy green vegetables have been linked to several outbreaks of human gastrointestinal infections. Antimicrobial interventions that are adoptable by the fresh produce industry for control of pathogen contamination are in great demand. This study was undertaken to evaluate the efficacy of sustained active packaging on control of Escherichia coli O157:H7 and total aerobic bacteria on lettuce. Commercial Iceberg lettuce was inoculated with a 3-strain mixture of E. coli O157:H7 at 10(2) or 10(4) CFU/g. The contaminated lettuce and un-inoculated controls were placed respectively in 5 different active packaging structures. Traditional, nonactive packaging structure was included as controls. Packaged lettuce was stored at 4, 10, or 22 °C for 3 wk and sampled weekly for the population of E. coli O157:H7 and total aerobic bacteria. Results showed that packaging structures with ClO2 generator, CO2 generator, or one of the O2 scavengers effectively controlled the growth of E. coli O157:H7 and total aerobic bacteria under all storage conditions. Packaging structure with the ClO2 generator was most effective and no E. coli O157:H7 was detected in samples packaged in this structure except for those that were inoculated with 4 log CFU/g of E. coli O157:H7 and stored at 22 °C. Packaging structures with an oxygen scavenger and the allyl isothiocyanate generator were mostly ineffective in control of the growth of the bacteria on Iceberg lettuce. The research suggests that some of the packaging structures evaluated in the study can be used to control the presence of foodborne pathogens on leafy green vegetables. PMID:25974213

  3. The impact of the pathogen Rhizoctonia solani and its beneficial counterpart Bacillus amyloliquefaciens on the indigenous lettuce microbiome.

    Erlacher, Armin; Cardinale, Massimiliano; Grosch, Rita; Grube, Martin; Berg, Gabriele

    2014-01-01

    Lettuce belongs to the most commonly raw eaten food worldwide and its microbiome plays an important role for both human and plant health. Yet, little is known about the impact of potentially occurring pathogens and beneficial inoculants of the indigenous microorganisms associated with lettuce. To address this question we studied the impact of the phytopathogenic fungus Rhizoctonia solani and the biological control agent Bacillus amyloliquefaciens FZB42 on the indigenous rhizosphere and phyllosphere community of greenhouse-grown lettuce at two plant stages. The rhizosphere and phyllosphere gammaproteobacterial microbiomes of lettuce plants showed clear differences in their overall and core microbiome composition as well as in corresponding diversity indices. The rhizosphere was dominated by Xanthomonadaceae (48%) and Pseudomonadaceae (37%) with Rhodanobacter, Pseudoxanthomonas, Dokdonella, Luteimonas, Steroidobacter, Thermomonas as core inhabitants, while the dominating taxa associated to phyllosphere were Pseudomonadaceae (54%), Moraxellaceae (16%) and Enterobacteriaceae (25%) with Alkanindiges, Pantoea and a group of Enterobacteriaceae unclassified at genus level. The preferential occurrence of enterics in the phyllosphere was the most significant difference between both habitats. Additional enhancement of enterics on the phyllosphere was observed in bottom rot diseased lettuce plants, while Acinetobacter and Alkanindiges were identified as indicators of healthy plants. Interestingly, the microbial diversity was enhanced by treatment with both the pathogen, and the co-inoculated biological control agent. The highest impact and bacterial diversity was found by Rhizoctonia inoculation, but FZB42 lowered the impact of Rhizoctonia on the microbiome. This study shows that the indigenous microbiome shifts as a consequence to pathogen attack but FZB42 can compensate these effects, which supports their role as biocontrol agent and suggests a novel mode of action. PMID

  4. The impact of the pathogen Rhizoctonia solani and its beneficial counterpart Bacillus amyloliquefaciens on the indigenous lettuce microbiome

    Armin eErlacher

    2014-04-01

    Full Text Available Lettuce belongs to the most commonly raw eaten food worldwide and its microbiome plays an important role for both human and plant health. Yet, little is known about the impact of potentially occurring pathogens and beneficial inoculants of the indigenous microorganisms associated with lettuce. To address this question we studied the impact of the phytopathogenic fungus Rhizoctonia solani and the biological control agent Bacillus amyloliquefaciens FZB42 on the indigenous rhizosphere and phyllosphere community of greenhouse-grown lettuce at two plant stages. The rhizosphere and phyllosphere gammaproteobacterial microbiomes of lettuce plants showed clear differences in their overall and core microbiome composition as well as in corresponding diversity indices. The rhizosphere was dominated by Xanthomonadaceae (48% and Pseudomonadaceae (37% with Rhodanobacter, Pseudoxanthomonas, Dokdonella, Luteimonas, Steroidobacter, Thermomonas as core inhabitants, while the dominating taxa associated to phyllosphere were Pseudomonadaceae (54%, Moraxellaceae (16% and Enterobacteriaceae (25% with Alkanindiges, Pantoea and a group of Enterobacteriaceae unclassified at genus level. The preferential occurrence of enterics in the phyllosphere was the most significant difference between both habitats. Additional enhancement of enterics on the phyllosphere was observed in bottom rot diseased lettuce plants, while Acinetobacter and Alkanindiges were identified as indicators of healthy plants. Interestingly, the microbial diversity was enhanced by treatment with both the pathogen, and the co-inoculated biological control agent. The highest impact and bacterial diversity was found by Rhizoctonia inoculation, but FZB42 lowered the impact of Rhizoctonia on the microbiome. This study shows that the indigenous microbiome shifts as a consequence to pathogen attack but FZB42 can compensate these effects, which supports their role as biocontrol agent and suggests a novel mode of

  5. Produção de alface em NFT e Floating aproveitando água salobra e o rejeito da dessalinização Lettuce production under NFT and Floating using brackish groundwater and the reject from its desalination

    Alexandre Nascimento dos Santos

    2011-06-01

    Full Text Available Plantas de alface cv. Elba foram cultivadas em dois sistemas hidropônicos, Floating e NFT, com o objetivo de avaliar três tipos de água: a água salobra natural (2,47 dS m-1 obtida a partir de um poço profundo; água doce (0,11 dS m-1 produzido por dessalinização por osmose inversa, e o rejeito salino (5,15 dS m-1, um efluente do processo de dessalinização. Estas águas foram combinadas em seis tratamentos resultantes da sua utilização alternada para preparar a solução nutritiva (SN e/ou substituir as perdas por evapotranspiração (ETc. O experimento foi conduzido em casa de vegetação na região semiárida de Pernambuco, utilizando 48 unidades experimentais em blocos casualizados em esquema fatorial 6x2 com quatro repetições. O rendimento da alface (massa de matéria fresca foi maior nas condições do Floating. O uso exclusivo da água do poço profundo e do rejeito de dessalinizadores diminuiu 22,7 e 39,6% a produção de alface, respectivamente. Para uma melhor combinação de águas doces e salobras, o uso de água salobra para repor a perda por ETc pode aumentar a produção de alface em relação ao uso dessas águas para preparar a SN, estes resultados foram registrados para a água do poço profundo e o rejeito.Plants of lettuce cv. Elba were grown under two hydroponic systems, Floating and NFT, aiming to evaluate three water resources: natural brackish water (2,47 dS m-1 obtained from a deep well; fresh water (0,11 dS m-1 produced by reverse osmosis desalination; and reject brine (5,15 dS m-1, a wastewater from desalination process. These waters were combined in six treatments resulted from their alternated use to prepare nutrient solution (NS and/or replace the evapotranspiration loss (ETc. The experiment was carried out under a greenhouse condition in the semiarid region of Pernambuco State, Brazil; 48 experimental units were used for both hydroponic systems. The lettuce yield (shoot fresh matter was higher under

  6. The Gas Exchange, Ultrastructure and Stress Resistance of Lettuce Plants under Short-Term Hypobaric and Hypoxic Conditions%短期低压低氧下莴苣的气体交换、超微结构和抗逆特性

    唐永康; 高峰; 郭双生

    2015-01-01

    To investigate the possibility of plants cultivation at hypobaria and hypoxia , the gas ex-change, ultrastructure and stress resistance of lettuce were conducted under short-term hypobaric and hy-poxic conditions.The gas exchange and growth of 25-day old lettuce (Lactuca sativa L.var.Rome) seed-lings were tested after 1-h or 24-h equilibration under two levels of total atmospheric pressure (101kPa and 30kPa)and three levels of oxygen partial pressure (21 kPa, 6 kPa and 2 kPa).The results showed that the biomass, ratio of root/shoot, water content and mineral contents of lettuce plants were not affect-ed by the changes of total atmospheric pressure and oxygen partial pressure;Under the same total pres-sure conditions (101 kPa or 30 kPa), hypoxia (6 kPa or 2 kPa) resulted in the increases of photosynthe-sis rate , soluble sugar and malondialdehyde and the reduction of dark respiration of lettuce leaves .The change of mitochondrion ultrastructure and the decrease of transpiration were found at 2 kPa oxygen par-tial pressure;Under the same oxygen partial pressure conditions , photosynthesis rate ,the chloroplast ul-trastructure ,the contents of chlorophyll and carotenoid of lettuce leaves were not affected by short-term hypobaric treatment (30 kPa) ,but the rates of dark respiration and transpiration increased and the con-tents of soluble sugar and malondialdehyde in lettuce leaves decreased .Lettuce can grow under short-term hypobaric and hypoxic conditions.Short-term hypoxia (6 kPa or 2 kPa) resulted in hypoxic stress and hypobaria(30 kPa) enhanced the stress resistance of lettuce .%为探索低压低氧环境中培养植物的可行性,研究了短期低压和低氧对莴苣气体交换、叶片超微结构和抗逆特性的影响。将莴苣植株(25天株龄)在两种总压(101 kPa和30 kPa )和三种氧分压(21 kPa、6 kPa和2 kPa)条件下进行了1小时和24小时平衡处理。发现短期低压和低氧均未影响莴苣植株生物量、根

  7. 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

    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

  8. Crop to wild introgression in lettuce: following the fate of crop genome segments in backcross populations

    Uwimana Brigitte

    2012-03-01

    Full Text Available Abstract Background After crop-wild hybridization, some of the crop genomic segments may become established in wild populations through selfing of the hybrids or through backcrosses to the wild parent. This constitutes a possible route through which crop (transgenes could become established in natural populations. The likelihood of introgression of transgenes will not only be determined by fitness effects from the transgene itself but also by the crop genes linked to it. Although lettuce is generally regarded as self-pollinating, outbreeding does occur at a low frequency. Backcrossing to wild lettuce is a likely pathway to introgression along with selfing, due to the high frequency of wild individuals relative to the rarely occurring crop-wild hybrids. To test the effect of backcrossing on the vigour of inter-specific hybrids, Lactuca serriola, the closest wild relative of cultivated lettuce, was crossed with L. sativa and the F1 hybrid was backcrossed to L. serriola to generate BC1 and BC2 populations. Experiments were conducted on progeny from selfed plants of the backcrossing families (BC1S1 and BC2S1. Plant vigour of these two backcrossing populations was determined in the greenhouse under non-stress and abiotic stress conditions (salinity, drought, and nutrient deficiency. Results Despite the decreasing contribution of crop genomic blocks in the backcross populations, the BC1S1 and BC2S1 hybrids were characterized by a substantial genetic variation under both non-stress and stress conditions. Hybrids were identified that performed equally or better than the wild genotypes, indicating that two backcrossing events did not eliminate the effect of the crop genomic segments that contributed to the vigour of the BC1 and BC2 hybrids. QTLs for plant vigour under non-stress and the various stress conditions were detected in the two populations with positive as well as negative effects from the crop. Conclusion As it was shown that the crop

  9. 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

    Dirceu Baumgartner

    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.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 irrigated 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

  10. GENETIC DIVERSITY AND RELATIONSHIPS BETWEEN WILD AND CULTIVATED POPULATIONS OF THE SEA LETTUCE, ENTEROMORPHA PROLIFERA, IN KOREA REVIALED BY RAPD MARKERS

    Huh, Man; Lee, Hak; Lee, Bok; Choi, Joo

    2004-01-01

    RAPD analysis was conducted to estimate genetic diversity and population structure of the wild (natural) and cultivated sea lettuce, Enteromorpha prolifera. The objectives of this study were to estimate the levels of genetic diversity in the wild and cultivated populations and to describe how the genetic variation of this species is distributed within and among its populations. In wild sea lettuce, 93.2% of loci at the species level showed polymorphism. The cultivated populations were found t...

  11. Agronomic and economic viability of intercropping onion and lettuce Viabilidade agroeconômica do cultivo consorciado de cebola e alface

    Wagner F. da Mota; Rosimeire D. Pereira; Gizeli de S Santos; Janiele Cássia B Vieira

    2012-01-01

    The study aimed to evaluate the agronomic and economic performance of intercropping onion and lettuce on four plant densities of each species. The experiment was set up in completely randomized blocks, with four replications and treatments arranged in a 4 x 4 factorial. Treatments resulted from a combination of four (100, 80, 60, and 40% of recommended plant densities in monoculture) plant densities for both lettuce and onion. Intercropping did not affect the agronomic performance of onion or...

  12. Stimulation of lettuce productivity by manipulation of diurnal temperature and light

    Knight, Sharon L.; Mitchell, Cary A.

    1983-01-01

    Salad Bowl and Waldmann's Green leaf lettuce (Lactuca sativa L.) were exposed to photosynthetic photon flux densities (PPFDs) of 444 or 889 micromol/s per sq m for 20 hrs/day under a diurnal temperature regime of 25-C days/15-C nights or 20-C days/15-C nights. Leaf dry weight of both cultivars was highest under the high PPFD/warm temperature regime and lowest under the low PPFD/cool temperature regime. Waldmann's Green yielded more than did Salad Bowl at 889 micromol/s per sq m and 25-C days/20-C nights. Under high PPFD, both cultivars yielded better with 25-C days/25-C nights than with 25-C days/20-C nights, although relative growth rates were the same under both temperature regimes.

  13. Comparison of fluorescent and high-pressure sodium lamps on growth of leaf lettuce

    Koontz, H. V.; Prince, R. P.; Koontz, R. F.; Knott, W. M. (Principal Investigator)

    1987-01-01

    Radiation from high-pressure sodium (HPS) lamps provided more than a 50% increased yield (fresh and dry weight of tops) of loose-leaf lettuce cultivars Grand Rapids Forcing and RubyConn, compared to that obtained by radiation from cool-white fluorescent (CWF) lamps at equal photosynthetic photon flux; yet, input wattage was approximately 36% less. It was postulated that the considerable output of 700 to 850 nm radiation from the HPS lamp was a significant factor of the increased yield. Under HPS lamps, the leaves of both cultivars were slightly less green with very little red pigmentation ('RubyConn') and slightly elongated, compared to CWF, but plant productivity per unit electrical energy input was vastly superior with HPS.

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

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

  15. Derivation of ozone flux-yield relationships for lettuce: A key horticultural crop

    Ozone flux-response relationships were derived for lettuce, employing a multiplicative approach to model the manner in which stomatal conductance is influenced by key environmental variables, using a dataset collected during field experimentation in Crete and yield-response relationships derived from parallel open-top chamber experiments. Regional agronomic practices were adopted throughout. Computed versus measured data revealed that the derived model explained 51% (P -2 s-1. Regressions employing very low or zero flux thresholds resulted in the strongest yield-flux relationships (explaining ∼80% (P < 0.05) of the variation in the dataset). - Establishment of ozone flux-yield relationships for a commercially-important horticultural crop grown widely in the Mediterranean

  16. Dissolution of rock phosphate in animal manure soil amendment and lettuce growth

    Kofi Agyarko; Akwasi Adutwum Abunyewa; Emmanuel Kwasi Asiedu; Emmanuel Heva

    2016-01-01

    A study was conducted in pots on the field to assess the effect of different quantities of poultry manure (PM), cattle manure (CM) and pig manure (PG) on the release of available phosphorus from Togo rock phosphate (RP) and lettuce growth. There were eleven (11) treatments which were: Control (soil only); 2.5g RP; 2.5g CM; 2.5gRP + 2.5g CM; 2.5gRP + 5gCM; 2.5gPM; 2.5gRP + 2.5gPM; 2.5gRP + 5gPM; 2.5gPG; 2.5gRP + 2.5gPG; 2.5gRP + 5gPG, applied per kg soil, using the Completely Randomized Design...

  17. Effectiveness of various disinfectants in the elimination of Yersinia enterocolitica on fresh lettuce.

    Escudero, M E; Velázquez, L; Di Genaro, M S; de Guzmán, A M

    1999-06-01

    The effectiveness of various disinfectants against two potentially pathogenic Yersinia enterocolitica strains (Y. enterocolitica W1024 O:9 [strain A] and Y. enterocolitica B O:5 Lis Xz [strain B]) on shredded lettuce was examined. Dip-wash treatments using 25, 100, and 300 ppm of chlorine at 4 and 22 degrees C, 0.2% Orenco Peel 40, 0.1% Tergitol, 0.5% acetic acid, and 0.5% lactic acid at 22 degrees C were performed. Surfactants and organic acids were also tested in combination with 100 ppm of chlorine. Reductions of Y. enterocolitica counts with 100 ppm (2.68 log10 for strain A and 2.36 log10 for strain B at 22 degrees C) and 300 ppm of chlorine (3.15 log10 for strain A and 2.55 log10 for strain B at 4 degrees C) were observed after 10 min. Inhibitory effect of different chlorine solutions was not significantly (P Dip solutions containing 0.1% Tergitol plus 100 ppm of chlorine produced a significant reduction of 2.73 log10 CFU/g in strain A (P lactic acid plus 100 ppm of chlorine combination, inactivation of Y. enterocolitica was >6 log10. The bactericidal effect of disinfectants was related to the concentration, exposure time, combination with chlorine (surfactants and organic acids), and susceptibility of each strain. Since the presence of pathogenic Y. enterocolitica on ready-to-use vegetables represents a health hazard, treatments as effective as 0.5% lactic acid plus 100 ppm of chlorine are recommended for washing of fresh lettuce. PMID:10382658

  18. Genotoxicity of Chlorpyrifos and the Antimutagenic Role of Lettuce Leaves in Male Mice

    Kamilia Badrakhan Abdelaziz

    2010-11-01

    Full Text Available Chlorpyrifos [O O-diethyl-O-(3 5 6-trichloro-2-pyridyl-phosphorothioate] is one of the most widelyused organophosphate insecticides. Previous studies proved that chlorpyrifos, at different doses,induced genotoxicity. In Egyptian foods, the residual levels of pesticides are often higher than thosefound in developed country ones. So the aim of this research was to evaluate the genotoxicity of theinsecticide chlorpyrifos at doses equal to its maximum residue limit (MRL in the leafy vegetables, itsdouble and quadruple (0.5, 1 and 2 mg/kg body weight in somatic and germ cells of male mice.In addition to that, evaluating the role of lettuce leaves as antigenotoxic in reducing the genotoxiceffects of chlorpyrifos tested doses when concurrently administrated to these animals. The studywas conducted on adult male laboratory mice at three levels: bone marrow cells as a model formitotic chromosome aberrations, spermatocytes as a model for meiotic chromosomes and spermcount and morphology. The results of the present study indicate that the treatment of male micewith chlorpyrifos by oral gavages for three months induced significant increase in the frequencies oftotal chromosomal aberrations in both somatic and germ cells in relation to control groups. Resultsof the sperm analysis showed that chlorpyrifos induced significant decrease in the sperm countwhen compared to negative control. Furthermore, it induced significant increase in head and tailsperm abnormalities, among which coiled tail was considered the most obvious sperm abnormalityinduced by chlorpyrifos. At the same time, the present study indicated that lettuce leaves feedconcurrently with three doses of chlorpyrifos could not protect cells from damage.

  19. The nitrogen and nitrate economy of butterhead lettuce (Lactuca sativa var capitata L).

    Broadley, Martin R; Seginer, Ido; Burns, Amanda; Escobar-Gutiérrez, Abraham J; Burns, Ian G; White, Philip J

    2003-09-01

    Quantifying and simulating the relationships between crop growth, total-nitrogen (total-N) and nitrate-N (NO3--N) concentration can improve crop nutritional husbandry. In this study, the relationship between shoot relative growth rate (RGR) and shoot total-N, organic-N and NO3--N concentration of hydroponically-grown lettuce (Lactuca sativa var. capitata L. cv. Kennedy) was described and simulated. Plants were grown hydroponically for up to 74 d. Nitrogen was supplied throughout (control; T1), or removed at 35 d (T2) and 54 d (T3), respectively, after sowing. The organic-N and NO3--N concentration declined in the shoots of control plants with growth, until commercial maturity approached when organic-N and NO3--N concentration increased. There were sub-linear relationships between both total-N and organic-N concentration, and shoot RGR, in the N-limited treatments, i.e. shoot RGR approached an asymptote at high shoot N concentration. The proportional effects of total-N and organic-N concentration on shoot RGR were independent of plant age. A dynamic simulation model ('Nicolet'), derived previously under different conditions, was used to simulate the growth, dry matter content, organic-N, and NO3--N concentration of lettuce grown under the extreme N-stress conditions experienced by the plants. In view of the largely successful fitting of the model to experimental data, the model was used to interpret the results. Suggestions for model improvement are made. PMID:12885858

  20. Lettuce cultivar mediates both phyllosphere and rhizosphere activity of Escherichia coli O157:H7.

    Richard S Quilliam

    Full Text Available Plant roots and leaves can be colonized by human pathogenic bacteria, and accordingly some of the largest outbreaks of foodborne illness have been associated with salad leaves contaminated by E. coli O157. Integrated disease management strategies often exploit cultivar resistance to provide a level of protection from economically important plant pathogens; however, there is limited evidence of whether the genotype of the plant can also influence the extent of E. coli O157 colonization. To determine cultivar-specific effects on colonization by E. coli O157, we used 12 different cultivars of lettuce inoculated with a chromosomally lux-marked strain of E. coli O157:H7. Lettuce seedlings grown gnotobiotically in vitro did exhibit a differential cultivar-specific response to E. coli O157 colonization, although importantly there was no relationship between metabolic activity (measured as bioluminescence and cell numbers. Metabolic activity was highest and lowest on the cultivars Vaila-winter gem and Dazzle respectively, and much higher in endophytic and tightly bound cells than in epiphytic and loosely bound cells. The cultivar effect was also evident in the rhizosphere of plants grown in compost, which suggests that cultivar-specific root exudate influences E. coli O157 activity. However, the influence of cultivar in the rhizosphere was the opposite to that in the phyllosphere, and the higher number and activity of E. coli O157 cells in the rhizosphere may be a consequence of them not being able to gain entry to the plant as effectively. If metabolic activity in the phyllosphere corresponds to a more prepared state of infectivity during human consumption, leaf internalization of E. coli O157 may pose more of a public health risk than leaf surface contamination alone.

  1. Proximate nutrient analyses of four species of submerged aquatic vegetation consumed by Florida manatee (Trichechus manatus latirostris) compared to romaine lettuce (Lactuca sativa var. longifolia).

    Siegal-Willott, Jessica L; Harr, Kendal; Hayek, Lee-Ann C; Scott, Karen C; Gerlach, Trevor; Sirois, Paul; Reuter, Mike; Crewz, David W; Hill, Richard C

    2010-12-01

    Free-ranging Florida manatees (Trichechus manatus latirostris) consume a variety of sea grasses and algae. This study compared the dry matter (DM) content, proximate nutrients (crude protein [CP], ether-extracted crude fat [EE], nonfiber carbohydrate [NFC], and ash), and the calculated digestible energy (DE) of sea grasses (Thalassia testudinum, Halodule wrightii, and Syringodium filiforme) collected in spring, summer, and winter, and an alga (Chara sp.) with those of romaine lettuce (Lactuca sativa var. longifolia). Neutral-detergent fiber (NDF), acid-detergent fiber (ADF), and lignin (L) measured after ash-extraction were also compared. Results of statistical tests (C = 0.01) revealed DM content was higher in aquatic vegetation than in lettuce (P = 0.0001), but NDF and ADF were up to threefold greater, EE (P = 0.00001) and CP (P = 0.00001) were 2-9 times less, and NFC (P = 0.0001) was 2-6 times lower in sea grass than in lettuce, on a DM basis. Chara was lower in NDF, ADF, L, EE, CP, and NFC relative to lettuce on a DM basis. Ash content (DM basis) was higher (P = 0.0001), and DE was 2-6 times lower in aquatic vegetation than in lettuce. Sea grass rhizomes had lower L and higher ash contents (DM basis) than sea grass leaves. Based on the nutrient analyses, romaine lettuce and sea grasses are not equivalent forages, which suggests that the current diet of captive Florida manatees should be reassessed. PMID:21370638

  2. Effect of gamma irradiation on microbial quality of minimally processed carrot and lettuce: A case study in Greater Accra region of Ghana

    The effect of ionizing radiation on the microbiological quality on minimally processed carrot and lettuce was studied. The aim was to investigate the effect of irradiation as a sanitizing agent on the bacteriological quality of some raw eaten salad vegetables obtained from retailers in Accra, Ghana. Minimally processed carrot and lettuce were analysed for total viable count, total coliform count and pathogenic organisms. The samples collected were treated and analysed for a 15 day period. The total viable count for carrot ranged from 1.49 to 14.01 log10 cfu/10 g while that of lettuce was 0.70 to 8.5 7 log10 cfu/10 g. It was also observed that total coliform count for carrot was 1.46–7.53 log10 cfu/10 g and 0.14–7.35 log10 cfu/10 g for lettuce. The predominant pathogenic organisms identified were Bacillus cereus, Cronobacter sakazakii, Staphylococcus aureus, and Klebsiella spp. It was concluded that 2 kGy was most effective for medium dose treatment of minimally processed carrot and lettuce. - Highlights: • The microbial load on the cut-vegetables was beyond acceptable level for consumption. • The microbial contamination of carrot was found to be higher than that of lettuce. • 2 kGy was most appropriate in treating cut-vegetables for microbial safety

  3. 农药胁迫对生菜叶片叶绿素荧光图像参数的影响%Effects of Pesticides on Chlorophyll Fluorescence Image Parameters of Lettuce Leaves

    孙俊; 宋彩惠; 毛罕平; 金夏明; 方敏; 张梅霞

    2014-01-01

    对生菜(Lactuca sativa)分别均匀喷洒浓度为70、140、280μg/L的杀虫剂氰戊菊酯,以清水为对照,以意大利全年耐抽薹生菜为试材,结果表明,随着农药浓度的增加,光系统Ⅱ的最大光化学效率、实际光化学效率、光化学淬灭系数和相对电子传递速率均下降,非光化学淬灭系数、非调节性能量耗散的量子产额和调节性能量耗散的量子产额上升,综合影响造成光系统Ⅱ的中心活性区域缩小、光合速率下降。另外生菜叶片自身的光化合保护机制能在一定程度上减轻农药的胁迫作用。与对照相比,光系统Ⅱ的实际光化学效率受农药影响最大,喷洒浓度为280μg/L的杀虫剂会对生菜光合作用过程产生持续性的、不可逆转的影响。%The Italy lettuce samples were sprayed evenly with water and pesticide fenvalerate with concentrations of 70,140,280 μg/L to study the adverse effect of pesticide on chlorophyll fluorescence parameters of lettuce leaves.With the increase of concentration of pesticide sprayed on the lettuce leaves,the biggest photosynthetic efficiency of photosystem Ⅱ(Fv/Fm),actual photosynthetic efficiency YI,photochemical quenching coefficient (qP) and relative electron transport rate declined and showed a clear decrease,meanwhile the non-photochemical quenching coefficient (qN),regulatory quantum yield of energy dissipation (Y NPQ) and non-regulatory quantum yield of energy dissipation (Y NO) increased significantly. Because of these disturbances,centre activity area of photosystem Ⅱ and actual photochemical efficiency was reduced. Light protection mechanisms of the lettuce leaves alleviated the impact of pesticides to a certain extent.Compared with control group,the actual photosynthetic efficiency of photosystem Ⅱ was one of the most exposed to effects from pesticide.The influence of 280μg/L pesticides on lettuce photosynthesis was continuous and irreversible.

  4. Allelopathy of Aqueous Extract From Tomato Plants on Lettuce and Celegy Cabbage%番茄植株水浸提液对生菜和大白菜化感作用的研究

    莫云容; 赵凯; 邓明华

    2015-01-01

    The study of allelopathy on tomato plants was made through measuring seedling growth of lettuce and celegy cabbage which were watered with the aqueous extract of tomato plants. The results lead to the following conclusions:① Tomato plants aqueous extract with lower concentration(0. 02 g/ml) re-strained length of seedling root and weight of celegy cabbage,while it prompted those of lettuce.②Toma-to plants aqueous extract with higher concentration ( 0 . 08 g/ml ) inhibited significantly both lettuce's length of seedling root as well as the weight of root and those of celegy cabbage;and the effects could be enhanced with the increase of the concentration.③Tomato plants aqueous extract in this concentration of 0. 04 g/ml,on one hand,which advanced seedling length of lettuces and root weight,root length and seed-ling length of celegy cabbages;on the other hand,which inhibited seedling length and root length of cele-gy cabbage.Tomato plant aqueous extract inhibited the ratio of seedling( root length)/( shoot length) of lettuce,while this turned to be helpful for Chinese cabbage. 5figs. ,1tab. ,11refs.%以生菜和大白菜两种蔬菜作物为受体,通过测定番茄植株水浸提液对两种蔬菜作物幼苗生长的影响,对番茄化感物质的作用进行了研究.结果表明:①低浓度(0.02 g/ml)的番茄水浸提液抑制大白菜幼苗的根长和根重;而促进生菜的根长和根重②高浓度(0.08 g/ml)的番茄水浸提液对生菜和大白菜幼苗根长、根重和苗长均表现为抑制作用.随着浓度的加大,抑制作用增强;③0.04 g/ml的番茄水浸提液对生菜幼苗苗长和大白菜的根重、根长/苗长有明显的促进作用,而对大白菜幼苗苗长、根长有抑制作用;榆番茄水浸提液对生菜幼苗根长/苗长比均表现为抑制作用、而对白菜的却表现为促进作用.图5,表1,参11.

  5. Uptake and distribution of bisphenol A and nonylphenol in vegetable crops irrigated with reclaimed water.

    Lu, Jian; Wu, Jun; Stoffella, Peter J; Wilson, P Chris

    2015-01-01

    The potential uptake and distribution of bisphenol A (BPA) and nonylphenol (NP) (from reclaimed irrigation water) in edible crops was investigated. BPA and NP were spiked into simulated reclaimed water at environmentally relevant concentrations. Two crops (lettuce, Lactuca sativa and tomato, Lycopersicon esculentum) were grown hydroponically in a greenhouse using the spiked irrigation water under two irrigation exposure scenarios (overhead foliar exposure and subsurface root exposure). BPA concentrations in tomato fruit were 26.6 ± 5.8 (root exposure) and 18.3 ± 3.5 (foliar exposure) μg kg(-1), while concentrations in lettuce leaves were 80.6 ± 23.1 (root exposure) and 128.9 ± 17.4 (foliar exposure) μg kg(-1). NP concentrations in tomato fruit were 46.1 ± 6.6 (root exposure) and 24.6 ± 6.4 (foliar exposure) μg kg(-1), while concentrations in lettuce leaves were 144.1 ± 9.2 (root exposure) and 195.0 ± 16.9 (foliar exposure) μg kg(-1). BPA was relatively mobile in lettuce plants regardless of exposure route. Limited mobility was observed for NP in both crops and BPA in tomatoes. The estimated daily intake of BPA and NP through consumption of vegetables irrigated with reclaimed water ranged from 8.9-62.9 to 11.9-95.1 μg, respectively, depending on the exposure route. PMID:25464330

  6. Water

    An up-date overview of the situation of the Austrian waters is given by analyzing the status of the water quality (groundwater, surface waters) and water protection measures. Maps containing information of nitrate and atrazine in groundwaters (analyses at monitoring stations), nitrate contents and biological water quality of running waters are included. Finally, pollutants (nitrate, orthophosphate, ammonium, nitrite, atrazine etc.) trends in annual mean values and median values for the whole country for the years 1992-1999 are presented in tables. Figs. 5. (nevyjel)

  7. Combined Water-Fertilizer Management to Minimize Non-Point Water Pollution While Achieving High Crop Production

    Letey, John; Jarrell, Wesley M

    1983-01-01

    Greenhouse and field experiments were conducted to characterize relationships between fertilizer and water management in irrigated vegetable production in California. Greenhouse trials were conducted both in hydroponic solution culture and in soil culture, with tomatoes and lettuce, to establish functional relationships between nitrogen and water uptake by single plants, and nitrogen recovery efficiency as a function of method and rate of application and placement for a simulated drip irrigat...

  8. Expression of H5 hemagglutinin vaccine antigen in common duckweed (Lemna minor) protects against H5N1 high pathogenicity avian influenza virus challenge in immunized chickens.

    Bertran, Kateri; Thomas, Colleen; Guo, Xuan; Bublot, Michel; Pritchard, Nikki; Regan, Jeffrey T; Cox, Kevin M; Gasdaska, John R; Dickey, Lynn F; Kapczynski, Darrell R; Swayne, David E

    2015-07-01

    A synthetic hemagglutinin (HA) gene from the highly pathogenic avian influenza (HPAI) virus A/chicken/Indonesia/7/2003 (H5N1) (Indo/03) was expressed in aquatic plant Lemna minor (rLemna-HA). In Experiment 1, efficacy of rLemna-HA was tested on birds immunized with 0.2μg or 2.3 μg HA and challenged with 10(6) mean chicken embryo infectious doses (EID50) of homologous virus strain. Both dosages of rLemna-HA conferred clinical protection and dramatically reduced viral shedding. Almost all the birds immunized with either dosage of rLemna-HA elicited HA antibody titers against Indo/03 antigen, suggesting an association between levels of anti-Indo/03 antibodies and protection. In Experiment 2, efficacy of rLemna-HA was tested on birds immunized with 0.9 μg or 2.2 μg HA and challenged with 10(6) EID50 of heterologous H5N1 virus strains A/chicken/Vietnam/NCVD-421/2010 (VN/10) or A/chicken/West Java/PWT-WIJ/2006 (PWT/06). Birds challenged with VN/10 exhibited 100% survival regardless of immunization dosage, while birds challenged with PWT/06 had 50% and 30% mortality at 0.9 μg HA and 2.2 μg HA, respectively. For each challenge virus, viral shedding titers from 2.2 μg HA vaccinated birds were significantly lower than those from 0.9μg HA vaccinated birds, and titers from both immunized groups were in turn significantly lower than those from sham vaccinated birds. Even if immunized birds elicited HA titers against the vaccine antigen Indo/03, only the groups challenged with VN/10 developed humoral immunity against the challenge antigen. None (rLemna-HA 0.9 μg HA) and 40% (rLemna-HA 2.2 μg HA) of the immunized birds challenged with PWT/06 elicited pre-challenge antibody titers, respectively. In conclusion, Lemna-expressed HA demonstrated complete protective immunity against homologous challenge and suboptimal protection against heterologous challenge, the latter being similar to results from inactivated whole virus vaccines. Transgenic duckweed-derived HA could be a

  9. Patogenicidade de Pythium aphanidermatum a alface cultivada em hidroponia e seu biocontrole com Trichoderma Pythium aphanidermatum pathogenicity to hydroponics lettuce and its biocontrol with Trichoderma

    Katya da Silva Patekoski

    2010-08-01

    Full Text Available O objetivo deste trabalho foi avaliar a patogenicidade de Pythium aphanidermatum a variedades de alface, e a ação do produto Biotrich, formulado com Trichoderma, no controle deste patógeno e na promoção do crescimento das plantas. Em experimento in vitro, plântulas recém-germinadas das variedades de alface Vera e Elisa foram colocadas em placas de Petri com ágar-água e 1 mL de suspensão do produto Biotrich (0,2 mL L-1 e, após 24 horas, em discos com micélio do isolado de Pythium. As avaliações foram realizadas após dez dias de incubação a 20 e 31ºC. Os testes in vivo foram realizados na primavera e verão, em sistema hidropônico "Nutrient Film Technique" (NFT, em delineamento inteiramente casualizado, em esquema fatorial 2x2x2, como segue: duas variedades; presença ou ausência do patógeno; e presença ou ausência de Biotrich. Ao final do cultivo, foram avaliadas as massas de matéria fresca e seca das plantas. No experimento in vitro, P. aphanidermatum apresentou maior agressividade a 31ºC. Contudo, não foi verificada patogenicidade nos testes in vivo. De modo geral, o Biotrich não promoveu o crescimento das plantas, mas foi efetivo no controle do patógeno in vitro. Pythium aphanidermatum é patogênico às variedades de alface Vera e Elisa, a 20 e 31ºC, e o Biotrich é efetivo para o controle desse patógeno nessas temperaturas.The objective of this work was to evaluate the pathogenicity of Pythium aphanidermatum to lettuce varieties, and the action of the product Biotrich, formulated with Trichoderma, in the control of this pathogen and its effect on plant growth promotion. In a in vitro experiment, germinated seedlings of Vera and Elisa lettuce varieties were placed in Petri dishes with water-agar and 1mL Biotrich suspension (0.2 mL L-1, and after 24 hours, on plugs with the Pythium isolate mycelium. The evaluations were done ten days after the incubation at 20 and 31ºC. In vivo experiments were carried out during

  10. Towards standard methods for the detection of Cryptosporidium parvum on lettuce and raspberries. Part 1: development and optimization of methods.

    Cook, N; Paton, C A; Wilkinson, N; Nichols, R A B; Barker, K; Smith, H V

    2006-06-15

    No standard method is available for detecting protozoan parasites on foods such as soft fruit and salad vegetables. We report on optimizing methods for detecting Cryptosporidium parvum on lettuce and raspberries. These methods are based on four basic stages: extraction of oocysts from the foodstuffs, concentration of the extract and separation of the oocysts from food materials, staining of the oocysts to allow their visualization, and identification of oocysts by microscopy. The concentration and separation steps are performed by centrifugation, followed by immunomagnetic separation using proprietary kits. Oocyst staining is also performed using proprietary reagents. The performance parameters of the extraction steps were extensively optimized, using artificially contaminated samples. The fully developed methods were tested several times to determine their reliability. The method to detect C. parvum on lettuce recovered 59.0+/-12.0% (n=30) of artificially contaminated oocysts. The method to detect C. parvum on raspberries recovered 41.0+/-13.0% (n=30) of artificially contaminated oocysts. PMID:16529835

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

    Smith, Hugh A; Chaney, William E

    2007-02-01

    Organic lettuce, Lactuca sativa L., producers on California's Central Coast rely on endemic syrphid flies (Diptera: Syrphidae) to suppress populations of Nasonovia ribisnigri Mosley (Homoptera: Aphididae) and other aphids affecting lettuce. Growers are using various forms of habitat manipulation to enhance biological control. We surveyed syrphids collected from organic romaine in and around the Salinas Valley from March through September 2005 to gain a better understanding of the species responsible for aphid suppression and to examine possible implications for biocontrol. The primary species of syrphid fly reared were Toxomerus marginatus (Say) (39%), Platycheirus stegnus (Say) (27%), Sphaerophoria sulfuripes (Thomson) (13%), and Allograpta obliqua (Say) (10%). Syrphus opinator Osten Sacken (2%), Toxomerus occidentalis (Curran) (1.3%), and Eupeodes volucris Osten Sacken (1%) were less common. Sphaerophoria pyrrhina Bigot, Scaeva pyrastri (L.), Platycheirus obscurus Say, Allograpta exotica Wiedemann, and Eupeodes americanus Wiedemann each made up parasitized by either Diplazon sp. (Hymenoptera: Ichneumonidae) or Pachyneuron sp. (Hymenoptera: Pteromalidae). PMID:17370807

  12. Effect of gamma irradiation and refrigeration storage on microbial, sensorial and chemical quality of fresh-cut lettuce

    Fresh-cut lettuce samples were collected and examined for their microbial, sensory and chemical qualities. All the examined samples had high level of microbial load. All examined samples contained Escherichia coli (E. coli), Enterococcus faecalis (Ent. faecalis), Staphylococcus aureus (S. aureus) and Aeromonas hydrophila (A. hydrophila), indicating that most these samples were unsatisfactory. Listeria monocytogenes (L monocytogenes) and Salmonella spp were not detected. Irradiation caused a great reduction in all microbial loads. During refrigerated storage, the counts of all microorganisms increased, but the rate of increase was slower in irradiated samples. Irradiation dose of 3 kGy was the optimum dose for preservation of fresh-cut lettuce which extended the refrigeration shelf-life up to 20 days and it was sufficient in eliminating all pathogenic bacteria without adverse effect on sensorial quality and slight effect on chemical quality.

  13. CO₂ enrichment can produce high red leaf lettuce yield while increasing most flavonoid glycoside and some caffeic acid derivative concentrations.

    Becker, Christine; Kläring, Hans-Peter

    2016-05-15

    Carbon dioxide (CO2) enrichment is a common practice in greenhouses to increase crop yields up to 30%. Yet, reports on the effect on foliar phenolic compounds vary. We studied the effect on two red leaf lettuce cultivars, grown for 25 days in growth chambers at CO2 concentrations of 200 or 1,000 ppm, with some plants exchanged between treatments after 11 days. As expected, head mass increased with higher CO2 concentration. Regression analysis, corrected for head mass, showed increased concentrations of most flavonoid glycosides at high CO2 concentrations while only some caffeic acid derivatives were increased, and not uniformly in both cultivars. Sugar concentrations increased with CO2 concentration. Generally, conditions in the 10 days before harvest determined concentrations. We suspect that phenolic compounds were mainly accumulated because plenty of precursors were available. The results indicate that CO2 enrichment can result in high yields of red leaf lettuce rich in phenolic compounds. PMID:26776031

  14. Heavy metals deposited in the culture of lettuce (Lactuca sativa L.) by the influence of vehicular traffic in Pernambuco, Brazil.

    França, Fernanda C S S; Albuuerque, Adriana M A; Almeida, Amanda C; Silveira, Patrícia B; Filho, Crescêncio A; Hazin, Clovis A; Honorato, Eliane V

    2017-01-15

    Currently one of the main sources of atmospheric pollution identified in urban centers is derived from both industrial and motor vehicle emissions. These pollutants can be adsorbed to particulate matter which is present in the air or deposited in the soil and plants, eventually reaching the human food chain. In this context, the present study aimed to determine the concentration of metals such as Cu, Pb, Cd, Ni and Zn in two subspecies of Lactuca sativa L. and in the soil from were lettuce samples were collected. The results for the soil samples analyzed show a possible contamination by Pb with concentration values as high as 140mg.kg(-1), which are above the Brazilian standards defined by Resolution CONAMA 420/2009 (Brazilian Environmental Council). However, the values found in the lettuce itself reveal that it is still suitable for consumption. PMID:27542464

  15. Zinc Fertilization Plus Liming to Reduce Cadmium Uptake by Romaine Lettuce on Cd-Mineralized Lockwood Soil

    Chaney, Rufus L.; Green, Carrie E.; Ajwa, Husein A; Smith, Richard F.

    2009-01-01

    Lockwood shaly loam (Pachic Argixerolls) and similar Cd mineralized soils derived from marine shale in California contain higher Cd levels and higher Cd:Zn ratios than uncontaminated US soils, and produce leafy vegetables with considerably higher Cd than is normal for US lettuce. Previous work by Burau et al. suggested that, in contrast with geogenic Zn+Cd enriched soils, liming the Cd-mineralized soils did not effectively reduce crop Cd concentration. Our previous studies found for high Cd:Z...

  16. Monitoring of pesticide residues in apples, lettuce and potato of the Slovene origin in the years 2001 to 2004

    Baša Česnik, Helena; Gregorčič, Ana; VELIKONJA BOLTA, Špela; Kmecl, Veronika

    2006-01-01

    Abstract 404 samples of apples, lettuce and potato produced in the Republic of Slovenia were analysed for pesticide residues at the Agricultural Institute of Slovenia in the years 2001 to 2004. Surveillance sampling in eight agricultural production areas was performed at market producers at the harvesting of products or in storehouses, after the pre-harvest interval of plant protection products used. Samples exceeding the maximum residue levels were the following: 3 apple samples (...

  17. Growth and yield characteristics of 'Waldmann's Green' leaf lettuce under different photon fluxes from metal halide or incandescent + fluorescent radiation

    Knight, Sharon L.; Mitchell, Cary A.

    1988-01-01

    Growth of 'Waldmann's Green' leaf lettuce under metal halide radiation was compared with that under In = Fl at the same photosynthetic photon flux (920 micromol/s/sq m) to evaluate the influence of lamp type on growth. No differences in leaf dry weight, leaf area, relative growth rate or photosynthesis occurred after 8 days of exposure to these radiation treatments for 20 h/day.

  18. Effect of Aerated Compost Tea on the Growth Promotion of Lettuce, Soybean, and Sweet Corn in Organic Cultivation

    Kim, Min Jeong; Shim, Chang Ki; Kim, Yong Ki; Hong, Sung Jun; Park, Jong Ho; Han, Eun Jung; Kim, Jin Ho; Kim, Suk Chul

    2015-01-01

    This study investigated the chemical characteristics and microbial population during incubation of four kinds of aerated compost teas based on oriental medicinal herbs compost, vermicompost, rice straw compost, and mixtures of three composts (MOVR). It aimed to determine the effects of the aerated compost tea (ACT) based on MOVR on the growth promotion of red leaf lettuce, soybean and sweet corn. Findings showed that the pH level and EC of the compost tea slightly increased based on the incub...

  19. Dynamic effects of soil bulk density on denitrification and mineralisation by 15N labelled lettuce residue and paper wastes

    Two laboratory incubation experiments aimed to study the denitrification and mineralisation influenced by different additives (15N labelled lettuce residue, paper wastes and mixture of both) and soil bulk densities were carried out by means of acetylene inhibition at the constant 15 degree C for 107 and 90 days, respectively. The results showed that the changes of N2O, CO2 emission rates, inorganic nitrogen (NO3- and NH4+), total N and 15N abundance in the soils which were affected by adding lettuce residue, paper wastes and mixture of both were investigated. Soil denitrification rate increased after lettuce residue was added into soil for 8 days. The maximum rate of N2O emission was 15 times higher than that in soil without any additive. However, paper wastes did not increase N2O emission in the first 8 days compared with other treatments, mixed residue and paper wastes could promote soil microbial activity, but N2O emission was lower than that in the soil with lettuce residue added and higher than that with paper wastes, indicating that mixture of residue and paper wastes was benefit to soil nitrogen immobilisation. CO2 emission in all the treatments were declined to the same level on the 107 th day. In the treatment added mixed residues and paper wastes, the released CO2 quantities were higher than those in other treatments every day. Effect of different bulk density on N2O and CO2 emission were response to the change of bulk density, it seems that N2O and CO2 emission increased with bulk density. High bulk density could affect decomposition of paper wastes and NO3-, NH4+ concentration. (30 ref., 10 tabs.)

  20. Yield and nutritional quality of greenhouse lettuce (Lactuca sativa L. as affected by genotype and production methods

    Govedarica-Lučić Aleksandra

    2014-01-01

    Full Text Available Greenhouse experiments were conducted in winter growing seasons in order to evaluate the effects of genotype and production methods on yield and nutritional quality of lettuce (Lactuca sativa L.. A three-year (2009-2011 study was conducted by randomized block system in a greenhouse without additional heating. The trial included three genotypes of lettuce (Archimedes RZ, Santoro RZ, Kibou RZ. Each row with these genotypes was exposed to the following variants of covering: control-planting on bare soil, mulching before sowing with PE-black foil, agro textile-covering plants after planting with agro textile (17 g, a combination of mulching + agro textile. Throughout of all the three years of the trial, it was continuously evidenced that the genotype “Santoro RZ” had the biggest heads and the highest yield (15.33 kg 10 m-2, which leads to conclusion that the yield of lettuce is a genotype characteristics. Moreover, the nutritional value (ascorbic acid concentration has shown that, depending on the method of production, in average, the combination of mulching + agro textile (26.77 mg 100 g-1 had the highest content while the control variant had significantly lower vitamin C content (21.10 mg 100 g-1. The three-year researches have shown that the production method and genotype significantly affect the nitrate content. An average nitrate content was 2196.33 mg kg-1 on the control variant, and 2526.24 mg kg-1 on agro textile. Leafy lettuce of genotyp „Kibou RZ“ had lower nitrate content (2176.85 mg kg-1 compared to „Archimedes RZ“ (2843.05 mg kg-1 and „Santoro RZ“ (2221.37 mg kg-1. However nitrate concentration in all treatments remained within the European Union’s permissible levels.