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

International Nuclear Information System (INIS)

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

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

International Nuclear Information System (INIS)

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

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Catalytic upgrading of duckweed biocrude in subcritical water.  

Science.gov (United States)

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

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

2014-08-01

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Modelling Ontogenetic Changes of Nitrogen and Water Content in Lettuce  

Science.gov (United States)

• Background and Aims It is well established that the nitrogen content of plants, including lettuce, decreases with time. It has also been observed that water content of lettuce increases between planting and harvest. This paper is an attempt at modelling these observations. • Methods An existing dynamic model (Nicolet), designed to predict growth and nitrate content of glasshouse lettuce, is modified to accommodate the ontogenetic changes of reduced-nitrogen and water contents (on a dry matter basis). The decreasing reduced-N content and the increasing water content are mimicked by dividing the originally uniform plant into ‘metabolically active’ tissue and ‘support’ tissue. The ‘metabolic’ tissue is assumed to contain a higher nitrogen content and a lower water content than the ‘support’ tissue. As the plants grow, the ratio of ‘support’ to ‘metabolic’ tissue increases, resulting in an increased mean water content and a decreased reduced-N content. Simulations with the new model are compared with experimental glasshouse data over four seasons. • Key Results The empirical linear relationship between water and reduced-N contents, matches, to a good approximation, the corresponding relationship based on the model. The agreement between the two makes it possible to effectively uncouple the estimation of the ‘ontogenetic’ parameters from the estimation of the other parameters. The growth and nitrate simulation results match the data rather well and are hardly affected by the new refinement. The reduced-N and water contents are predicted much better with the new model. • Conclusion Prediction of nitrogen uptake for the substantial nitrate pool of lettuce depends on the water content. Hence, the modified model may assist in making better fertilization decisions and better estimates of nitrogen leaching. PMID:15294851

SEGINER, IDO; BLEYAERT, PETER; BREUGELMANS, MAAIKE

2004-01-01

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

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

Holvoet, Kevin; Sampers, Imca; Haute, Sam; Jacxsens, Liesbeth; Uyttendaele, Mieke

2012-01-01

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Effects of Mulch and Irrigation Water Amounts on Lettuce`s Yield, Evapotranspiration, Transpiration and Soil Evaporation in Isparta Location, Turkey  

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Full Text Available The effects of mulch and the several irrigation water amounts on soil evaporation and on lettuce`s transpiration, evapotranspiration and yield were studied in a glasshouse pot experiment as Completely Randomised Experimental Design with three replications during 2001 (August 10 to October 2 at the Experimental Glasshouse in the Campus of the University of Süleyman Demirel, Turkey. Water losses by evaporation and/or transpiration were measured daily by weighing the pots. Irrigation water was applied twice a week. The water quantities were regulated by weight. Increasing the amount of irrigation water applied significantly increased crop evapotranspiration (mean 45% in the Open Soil Surface (OSS treatments and transpiration (mean 26% in the Covered Soil Surface (CSS treatments. In CSS treatments, evapotranspiration was significantly reduced, while transpiration was significantly increased compared with OSS treatments. Covering the soil surface reduced the amount of irrigation water required by the lettuce crop by about 60% for all irrigation treatments compared with the amount of irrigation water added in the OSS treatments, because wet soil surface evaporation was eliminated. The contribution of soil evaporation to total evapotranspiration and evaporation-transpiration ratio varied from a minimum of 40 and 66% at highest water level to maximum of 49 and 94% at lowest water level, respectively. Lettuce yield was significantly higher in CSS treatments than in OSS treatments. Especially at low water levels, lettuce yield was higher in CSS than in OSS treatment. Water use efficiency in CSS and OSS treatments was maximum for the highest water level and irrigation water use efficiency was maximum for the lower water level in CSS treatments and for the intermediate water level in OSS treatments.

Kadayifci Abdullah

2004-01-01

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

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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 ...

Snow, A. M.; Ghaly, Abdel E.

2008-01-01

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

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

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

2012-01-01

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

11

EFFECTIVENESS OF ELECTROLYZED OXIDIZING WATER FOR INACTIVATING Listeria monocytogenes IN LETTUCE  

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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.

Casadiego Laíd Paola

2005-06-01

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

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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.

Ömer Hulusi Dede

2011-06-01

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Transfer of Escherichia coli O157:H7 to romaine lettuce due to contact water from melting ice.  

Science.gov (United States)

Ice can be used to chill romaine lettuce and maintain relative humidity during transportation. Escherichia coli O157:H7 may contaminate water used for ice. The objective of this study was to determine the potential for E. coli O157:H7 contamination of romaine lettuce from either ice contaminated with the pathogen or by transfer from lettuce surfaces via melting ice. In experiment 1, lettuce was spot inoculated with E. coli O157:H7 and chilled with ice prepared from uncontaminated tap water. In experiment 2, water inoculated with this pathogen was frozen and used to ice lettuce. Three heads of lettuce were stacked in each container and stored at 4 or 20 degrees C. After the ice melted, E. coli O157:H7 attachment to and recovery from the lettuce leaves were determined. For experiment 1, the population of E. coli O157:H7 attached to inoculated sites averaged 3.8 and 5.5 CFU/cm2 at 4 and 20 degrees C, respectively. Most of the uninoculated sites became contaminated with the pathogen due to ice melt. For experiment 2, 3.5 to 3.8 log CFU E. coli O157:H7 per cm2 was attached to the top leaf on the first head. After rinsing with chlorinated water (200 microg/ml), E. coli O157:H7 remained on the surface of the top head (1.8 to 2.0 log CFU/cm2). There was no difference in numbers of E. coli O157:H7 recovered from each sampling site at 4 and 20 degrees C. Results show that E. coli O157:H7 can be transferred onto other produce layers in shipping containers from melted ice made of contaminated water and from contaminated to uncontaminated leaf surfaces. PMID:18326172

Kim, Jin Kyung; Harrison, Mark A

2008-02-01

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

Directory of Open Access Journals (Sweden)

Full Text Available This study was carried out to assess the levels of different heavy metals like Iron, Manganese, Copper, Zinc, Cadmium and Lead in three different irrigation water sources, irrigated soils and irrigated lettuce. The result indicates positive and significant correlation of heavy metals concentrations between the irrigation water, irrigated soils and irrigated lettuce. The range of various heavy metals in drained water irrigated lettuce was 162.00-190.00, 60.25-78.25, 6.03-8.80 and 23.88-52.00 mg/kg in Fe, Mn, Cu and Zn, respectively. Generally, mean heavy metal concentrations of the water, soil and lettuce from two vegetable growing sites were within the FAO/WHO recommended maximum concentrations for crop production. Although the levels of heavy metals in the irrigation water, irrigated soils and irrigated lettuce were below the recommended limits, regular monitoring of these metal levels from these sources is essential to prevent excessive heavy metal buildup in vegetables in general.

Mark O. Akrong

2012-05-01

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

Science.gov (United States)

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

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

2014-02-01

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Duck-Weed as an ecotoxicological biotest  

International Nuclear Information System (INIS)

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

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Physicochemical quality and chemical safety of chlorine as a reconditioning agent and wash water disinfectant for fresh-cut lettuce washing  

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Chlorine was assessed as a reconditioning agent and wash water disinfectant in the fresh-cut produce industry. Artificial fresh-cut lettuce wash water, made from butterhead lettuce, was used for the experiments. In the reconditioning experiments, chlorine was added to artificial wash water inoculated with Escherichia coli O157 (6 log CFU/ml). Regression models were constructed based on the inactivation data and validated in actual wash water from leafy vegetable processing companies. The mode...

Haute, Sam; Sampers, Imca; Holvoet, Kevin; Uyttendaele, Mieke

2013-01-01

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Efficacy of antimicrobial agents in lettuce leaf processing water for control of Escherichia coli O157:H7.  

Science.gov (United States)

The objectives of this research were to study transfer and control of Escherichia coli O157:H7 during simultaneous washing of inoculated and uninoculated lettuce pieces and to determine the efficacy of antimicrobial agents (peroxyacetic acid, mixed peracid, and sodium hypochlorite) on reducing the transfer of E. coli O157:H7 through processing water with or without organic load. Lettuce leaf pieces (5 by 5 cm) were inoculated with a five-strain mixture of green fluorescent protein-labeled E. coli O157:H7 at 5.6 log CFU per piece. One inoculated lettuce piece was added to five uninoculated leaves during washing. Peroxyacetic acid and mixed peracid were tested at 10, 20, and 30 ppm, and chlorine was tested at 30 and 50 ppm. No organic load (liquefied lettuce leaves) and 10% organic load in processing water were compared. Without organic load, peroxyacetic acid at 30 ppm, mixed peracid at 10, 20, and 30 ppm, and chlorine at 30 and 50 ppm all significantly reduced E. coli O157: H7 in processing water by 1.83, 1.73, 1.50, 1.83, 1.34, and 1.83 log CFU/ml, respectively, compared with washing with water alone. These antimicrobials at all concentrations tested also significantly reduced transfer of the bacteria from an inoculated leaf to uninoculated leaves in the processing water by 0.96 to 2.57 log CFU per piece. A 10% organic load in the processing water reduced efficacy of antimicrobial agents. In this contaminated water, peroxyacetic acid at 10 and 20 ppm and chlorine at 30 ppm produced effects not significantly different from those of water alone. Therefore, it is important to understand the impact of organic load when validating the effectiveness of antimicrobial treatments. PMID:19681260

Zhang, Guodong; Ma, Li; Phelan, Vanessa H; Doyle, Michael P

2009-07-01

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

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

Juan Esquivel

2008-09-01

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

Science.gov (United States)

It is accepted that irrigation water is a potential carrier of enteric pathogens, such as Salmonella and E. coli O157:H7 and, therefore, a source for contamination of fresh produce. We tested this by comparing irrigation water samples taken from five different greenhouses in Belgium. The water samples were inoculated with four zoonotic strains, two Salmonella and two E. coli O157:H7 strains, and pathogen survival and growth in the water were monitored up till 14 days. The influence of water temperature and chemical water quality was evaluated, and the survival tests were also performed in water samples from which the resident aquatic microbiota had previously been eliminated by filter sterilization. The pathogen's survival differed greatly in the different irrigation waters. Three water samples contained nutrients to support important growth of the pathogens, and another enabled weaker growth. However, for all, growth was only observed in the samples that did not contain the resident aquatic microbiota. In the original waters with their specific water biota, pathogen levels declined. The same survival tendencies existed in water of 4 °C and 20 °C, although always more expressed at 20 °C. Low water temperatures resulted in longer pathogen survival. Remarkably, the survival capacity of two E. coli 0157:H7 strains differed, while Salmonella Thompson and Salmonella Typhimurium behaved similarly. The pathogens were also transferred to detached lettuce leaves, while suspended in two of the water samples or in a buffer. The effect of the water sample on the pathogen's fitness was also reproduced on the leaves when stored at 100% relative humidity. Inoculation of the suspension in buffer or in one of the water samples enabled epiphytic growth and survival, while the pathogen level in the other water sample decreased once loaded on the leaves. Our results show that irrigation waters from different origin may have a different capacity to transmit enteric pathogens and an important impact on the fitness of the pathogens to sustain and even grow on the leaf surface. PMID:25268508

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

2014-01-01

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

Science.gov (United States)

It is accepted that irrigation water is a potential carrier of enteric pathogens, such as Salmonella and E. coli O157:H7 and, therefore, a source for contamination of fresh produce. We tested this by comparing irrigation water samples taken from five different greenhouses in Belgium. The water samples were inoculated with four zoonotic strains, two Salmonella and two E. coli O157:H7 strains, and pathogen survival and growth in the water were monitored up till 14 days. The influence of water temperature and chemical water quality was evaluated, and the survival tests were also performed in water samples from which the resident aquatic microbiota had previously been eliminated by filter sterilization. The pathogen’s survival differed greatly in the different irrigation waters. Three water samples contained nutrients to support important growth of the pathogens, and another enabled weaker growth. However, for all, growth was only observed in the samples that did not contain the resident aquatic microbiota. In the original waters with their specific water biota, pathogen levels declined. The same survival tendencies existed in water of 4 °C and 20 °C, although always more expressed at 20 °C. Low water temperatures resulted in longer pathogen survival. Remarkably, the survival capacity of two E. coli 0157:H7 strains differed, while Salmonella Thompson and Salmonella Typhimurium behaved similarly. The pathogens were also transferred to detached lettuce leaves, while suspended in two of the water samples or in a buffer. The effect of the water sample on the pathogen’s fitness was also reproduced on the leaves when stored at 100% relative humidity. Inoculation of the suspension in buffer or in one of the water samples enabled epiphytic growth and survival, while the pathogen level in the other water sample decreased once loaded on the leaves. Our results show that irrigation waters from different origin may have a different capacity to transmit enteric pathogens and an important impact on the fitness of the pathogens to sustain and even grow on the leaf surface. PMID:25268508

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

2014-01-01

22

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

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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...

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

2009-01-01

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Water-soluble compounds of lettuce inhibit DNA damage and lipid peroxidation induced by glucose/serum deprivation in N2a cells.  

Science.gov (United States)

Oxidative stress, increase of lipid peroxidation and resultant DNA damage are associated with pathophysiology of many human diseases such as acute and chronic CNS injuries and diseases, cancer, and also aging. This work was done to investigate whether water fraction from the hydroalcoholic extract of green leaf lettuce (Lactuca sativa L.) can protect N2a cells against glucose/serum deprivation (GSD)-induced lipid peroxidation and DNA fragmentation. The cells were cultivated for 12 h in GSD condition in the absence or presence of the lettuce fraction. The total antioxidant ability of the lettuce water fraction was determined using ferric reducing antioxidant power (FRAP) assay. The intracellular lipid peroxidation was evaluated by malondialdehyde (MDA) level. DNA damage was determined using single cell gel electrophoresis. Using FRAP assay, the antioxidant activity of lettuce water fraction was found to be 574 micromol/g, which is equivalent to 64.1 mg of pure ascorbic acid. Exposure of the cells to GSD condition led to a significant increase of MDA level and DNA fragmentation. Lettuce extract at 400 microg/mL could decrease the elevated intracellular lipid peroxidation and DNA damage. The present study demonstrates that lettuce exerts genoprotective effect through inhibition of oxidative stress. PMID:25265820

Asadpour, Elham; Ghorbani, Ahmad; Sadeghnia, Hamid R

2014-01-01

24

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

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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 (effects on both studied lettuce varieties, namely yield reduction (up to 53% and 87% in autumn and summer experiments, respectively) and increase of uranium leaf concentration (up to 1.4 and 7 fold in autumn and summer, respectively). Effect on lettuce yield was mainly due to the high soil salinity (1.01 to 6.31 mS/cm) as a consequence of high irrigation water electrical conductivity (up to 1.82 mS/cm) and low lettuce soil salinity tolerance (1 to 3 mS/cm). The highest lettuce uranium concentration (dry weight) observed was 2.13 and 5.37 mg/kg for Marady and Romana variety, respectively. The highest uranium lettuce concentration in Romana variety was also the effect of its growing in summer season when it was subject to greatest frequency and amount of water irrigation. The consumption by an adult of the lettuce that concentrate more uranium, represents only 16.7% of the tolerable daily limit intake set by World Health Organisation for this element (0.6 mg/kg body weight daily), suggesting that lettuce uranium intake had a low contribution and do not represent a potential health risk for Cunha Baixa's residents.

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

2012-04-01

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

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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.

Humberto Brevilato Novaes

2009-01-01

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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 t [...] o 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.

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

1647-16-01

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

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

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

2010-01-01

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

Science.gov (United States)

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.

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

2001-03-01

30

[XANES study of lead speciation in duckweed].  

Science.gov (United States)

Qixiashan lead-zinc mine of Nanjing was one of the largest lead zinc deposits in East China Its exploitation has been over 50 years, and the environmental pollution has also been increasing. The lead concentration in the local environment was high, but lead migration and toxic mechanism has not been clear. Therefore, biogeochemistry research of the lead zinc mine was carried out. Using ICP-MS and Pb-L III edge XANES, lead concentration and speciation were analyzed respectively, and duckweed which can tolerate and enriched heavy metals was found in the pollution area. The results showed that the lead concentration of duckweed was 39.4 mg x kg(-1). XANES analysis and linear combination fit indicated that lead stearate and lead sulfide accounted for 65% and 36.9% respectively in the lead speciation of duckweed, suggesting that the main lead speciation of duckweed was sulfur-containing lead-organic acid. PMID:23016367

Chu, Bin-Bin; Luo, Li-Qiang; Xu, Tao; Yuan, Jing; Sun, Jian-Ling; Zeng, Yuan; Ma, Yan-Hong; Yi, Shan

2012-07-01

31

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

Scientific Electronic Library Online (English)

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

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

2012-02-01

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

Scientific Electronic Library Online (English)

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

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

2011-05-01

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Effect of duckweed cover on greenhouse gas emissions and odour release from waste stabilisation ponds.  

Science.gov (United States)

Treatment of wastewater in stabilisation pond systems prevents the negative environmental impact of uncontrolled disposal of sewage. However, even a natural treatment system may generate secondary negative environmental impacts in terms of energy consumption, emission of greenhouse gases and emission of odorous compounds. Whereas natural systems have an advantage over electro-mechanical systems in that they use less hardware and less energy, it is not yet known whether secondary environmental effects in the form of greenhouse gas emissions are lower for these systems. This research intends to be a first step in the direction of answering this question by assessing gas emissions from two types of natural systems, namely algae-based and duckweed-based stabilisation ponds. The H2S volatilisation from laboratory scale pond-reactors has been determined by drawing the air above the water surface continuously through a solution of 1 M NaOH for absorption of sulphide. The amount of H2S that volatilised from the algae pond-reactor, and was trapped in the NaOH trap, was found to be 2.5-86 mg/m2/day. The H2S volatilisation from the duckweed pond-reactor was found to be negligible, even though the sulphide concentration was 9.7 mg/l S(2-). The duckweed cover was a physical barrier for volatilisation, since bubbles were trapped in the cover. In addition the duckweed layer was found to be afavourable environment for both aerobic sulphide oxidisers (Beggiatoa gigantae) as well as for photosynthetic purple sulphur bacteria belonging to the genus Chromatium. These may also have contributed to the prevention of H2S volatilisation. Results on methane emissions were not conclusive so far, but the same mechanisms that prevent H2S volatilisation may also prevent methane volatilisation. Therefore it was concluded that duckweed covers on stabilisation ponds may reduce the emission of both odorous and greenhouse gases. PMID:14510229

van der Steen, N P; Nakiboneka, P; Mangalika, L; Ferrer, A V M; Gijzen, H J

2003-01-01

34

Germinação e formação de mudas de alface em diferentes níveis de salinidade de água Germination and seedling development of lettuce in relation to water salinity  

Directory of Open Access Journals (Sweden)

Full Text Available Tendo em vista a magnitude dos problemas de salinidade na região Nordeste e a inexistência de indicativos de tolerância da cv. Elba de alface à salinidade, estudou-se, no delineamento inteiramente casualizado, os efeitos de 6 níveis de condutividade elétrica da água de irrigação (CEa, entre 0,3 e 3,8 dS m-1, sobre o vigor e a formação de mudas de alface. As águas foram preparadas mantendo-se proporção equivalente 7:2:1, respectivamente, entre Na:Ca:Mg. Todas as variáveis estudadas foram afetadas pela salinidade, tanto na germinação quanto em fase de muda, no entanto, CEa de 3,8 dS m-1, considerada como de elevada restrição agrícola, proporcionou 90% de germinação relativa, 61% de vigor de plântulas (média entre as variáveis avaliadas e mudas com 50% de crescimento, podendo-se classificar a alface como moderadamente tolerante à salinidade na germinação e moderadamente sensível na fase de plântula e de muda.Keeping in view the magnitude of the salinity problems in the Northeast region and the inexistence of salinity tolerance indications for lettuce cv. Elba, an experiment was carried out in a completely randomized design, with the objective of studying the effects of 6 levels of electrical conductivity of the irrigation water (ECw varying from 0.3 to 3.8 dS m-1 on the vigor and formation of lettuce seedling. The irrigation water of desired ECw was prepared maintaining equivalent proportion of 7:2:1, among Na:Ca:Mg, respectively. All the variables studied were affected by salinity during germination and in the seedling stage, however ECw of 3.8 dS m-1, considered as being of severe agricultural restriction, provided on average 90% of relative germination, 61% of vigor and seedling with 50% growth, permits to classify lettuce as moderately tolerant to salinity during germination and moderately sensitive in the seedling phase.

Sergio B. A. Viana

2001-05-01

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Using full-scale duckweed ponds as the finish stage for swine waste treatment with a focus on organic matter degradation.  

Science.gov (United States)

The rapid increase in the number of swine has caused pronounced environmental impacts worldwide, especially on water resources. As an aggregate, smallholdings have an important role in South American pork production, contributing to the net diffusion of pollution. Thus, duckweed ponds have been successfully used for swine waste polishing, mainly for nutrient removal. Few studies have been carried out to assess organic matter degradation in duckweed ponds. Hence, the present study evaluated the efficiency of two full-scale duckweed ponds for organic matter reduction of swine waste on small pig farms. Duckweed ponds, in series, received the effluent after an anaerobic biodigester and storage pond, with a flow rate of 1 m(3) day(-1). After 1 year of monitoring, an improvement in effluent quality was observed, with a reduction in biochemical oxygen demand (BOD) and total chemical oxygen demand (tCOD), respectively, of 94.8 and 96.7%, operating at a loading rate of approximately 27 kgBOD ha(-1) day(-1) and 131 kgCOD ha(-1) day(-1). Algae inhibition due to duckweed coverage was strongly observed in the pond effluent, where chlorophyll a and turbidity remained below 25 ?g L(-1) and 10 NTU. Using the study conditions described herein, duckweed ponds were shown to be a suitable technology for swine waste treatment, contributing to the environmental sustainability of rural areas. PMID:24845333

Mohedano, R A; Costa, R H R; Hofmann, S M; Belli Filho, P

2014-01-01

36

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

Scientific Electronic Library Online (English)

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

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

37

Mutations in Lettuce Improvement  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

2011-01-01

38

Laboratory and pilot-scale dead-end ultrafiltration concentration of sanitizer-free and chlorinated lettuce wash water for improved detection of Escherichia coli O157:H7.  

Science.gov (United States)

An automated dead-end (single pass, no recirculation) ultrafiltration device, the Portable Multi-use Automated Concentration System (PMACS), was evaluated as a means to concentrate Escherichia coli O157:H7 from 40 liters of simulated commercial lettuce wash water. The assessment included generating, sieving, and concentrating sanitizer-free lettuce wash water, either uninoculated or inoculated with green fluorescent protein-transformed E. coli O157:H7 at a high (1.00 log CFU/ml) or low (-1.00 log CFU/ml) concentration. Cells collected within the filters were recovered in approximately 400 ml of buffer to create lettuce wash retentates. The extent of concentration was determined by viable plate counts using a medium selective for the transformed E. coli O157:H7. The samples were qualitatively analyzed for E. coli O157:H7 according to the U. S. Food and Drug Administration Bacteriological Analytical Manual enrichment method and with an electrochemiluminescence immunoassay. This concentration method was then evaluated in a pilot-scale production line at Michigan State University using chlorinated (100, 30, and 10 ppm of available chlorine) lettuce wash water. The total PMACS processing times were 82 ± 6 and 65 ± 5 min for sanitizer-free and chlorinated washes, respectively. Overall, E. coli O157:H7 populations were approximately 2 log higher in retentates than in unconcentrated lettuce wash samples. The higher E. coli O157:H7 levels in the retentates enabled cultural and electrochemiluminescence immunoassay detection in some samples when the corresponding lettuce wash samples were negative. When combined with standard and rapid detection methods, the PMACS concentration method may provide a means to enhance pathogen monitoring of produce wash water. PMID:25198586

Magaña, Sonia; Schlemmer, Sarah M; Davidson, Gordon R; Ryser, Elliot T; Lim, Daniel V

2014-08-01

39

Effect of dim light irradiation on preservation of fresh lettuce  

International Nuclear Information System (INIS)

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

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

Science.gov (United States)

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

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

2001-01-01

 
 
 
 
41

Accumulation and retention of lead by cattail (Typha domingensis), hydrilla (Hydrilla verticillata), and duckweed (Lemna obscura).  

Science.gov (United States)

Investigation of lead levels in Delaney Creek, which flows through a former lead-acid battery manufacturing and disposal site in Tampa, FL, revealed low but significant lead levels in the water and sediments along the creek, Known phytoaccumulator plants populate certain locations within the creek and adjacent wetlands. Three representative plants from the study site--cattail (Typha domingensis Pers.), hydrilla (Hydrilla verticillata Royle), and duckweed (Lemna obscura L.)--were investigated for their potential to remove lead from contaminated waters under the controlled conditions of a phytotron room. The plants were collected at the site and cultured in hydroponic medium under conditions that mimicked their natural environment (26 degrees C and 80% humidity). Results indicate that, of the three species, duckweed and hydrilla achieve high lead removal efficiencies after a short exposure period (98% removal using hydrilla, 97% with duckweed after one week of exposure) while cattail appears to be less efficient than the other two species. The kinetic rates of lead removal were studied for Lemna obscura. PMID:12369634

Gallardo-Williams, Maria T; Whalen, Valerie A; Benson, Robert F; Martin, Dean F

2002-09-01

42

Efficacy of sodium hypochlorite and peroxyacetic acid to reduce murine norovirus 1, B40-8, Listeria monocytogenes, and Escherichia coli O157:H7 on shredded iceberg lettuce and in residual wash water.  

Science.gov (United States)

The efficiency of sodium hypochlorite (NaOCl) and peroxyacetic acid (PAA) to reduce murine norovirus 1 (MNV-1), a surrogate for human norovirus, and Bacteroides fragilis HSP40-infecting phage B40-8 on shredded iceberg lettuce was investigated. The levels of removal of viruses MNV-1 and B40-8 were compared with the reductions observed for bacterial pathogens Listeria monocytogenes and Escherichia coli O157:H7. Two inoculation levels, one with a high organic load and the other containing a 10-fold lower number of pathogens and organic matter, showed that the effectiveness of NaOCl was greatly influenced by the presence of organic material, which was not observed for PAA. Moreover, the present study showed that 200 mg/liter NaOCl or 250 mg/liter PAA is needed to obtain an additional reduction of 1 log (compared with tap water) of MNV-1 on shredded iceberg lettuce, whereas only 250 mg/liter PAA achieved this for bacterial pathogens. None of the treatments resulted in a supplementary 1-log PFU/g reduction of B40-8 compared with tap water. B40-8 could therefore be useful as an indicator of decontamination processes of shredded iceberg lettuce based on NaOCl or PAA. Neither MNV-1, B40-8, nor bacterial pathogens could be detected in residual wash water after shredded iceberg lettuce was treated with NaOCl and PAA, whereas considerable numbers of all these microorganisms were found in residual wash water consisting solely of tap water. This study illustrates the usefulness of PAA and NaOCl in preventing cross-contamination during the washing process rather than in causing a reduction of the number of pathogens present on lettuce. PMID:19517733

Baert, Leen; Vandekinderen, Isabelle; Devlieghere, Frank; Van Coillie, Els; Debevere, Johan; Uyttendaele, Mieke

2009-05-01

43

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

Directory of Open Access Journals (Sweden)

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

Ursula Wolf

2012-09-01

44

Germinação e formação de mudas de alface em diferentes níveis de salinidade de água / Germination and seedling development of lettuce in relation to water salinity  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Tendo em vista a magnitude dos problemas de salinidade na região Nordeste e a inexistência de indicativos de tolerância da cv. Elba de alface à salinidade, estudou-se, no delineamento inteiramente casualizado, os efeitos de 6 níveis de condutividade elétrica da água de irrigação (CEa), entre 0,3 e 3 [...] ,8 dS m-1, sobre o vigor e a formação de mudas de alface. As águas foram preparadas mantendo-se proporção equivalente 7:2:1, respectivamente, entre Na:Ca:Mg. Todas as variáveis estudadas foram afetadas pela salinidade, tanto na germinação quanto em fase de muda, no entanto, CEa de 3,8 dS m-1, considerada como de elevada restrição agrícola, proporcionou 90% de germinação relativa, 61% de vigor de plântulas (média entre as variáveis avaliadas) e mudas com 50% de crescimento, podendo-se classificar a alface como moderadamente tolerante à salinidade na germinação e moderadamente sensível na fase de plântula e de muda. Abstract in english Keeping in view the magnitude of the salinity problems in the Northeast region and the inexistence of salinity tolerance indications for lettuce cv. Elba, an experiment was carried out in a completely randomized design, with the objective of studying the effects of 6 levels of electrical conductivit [...] y of the irrigation water (ECw) varying from 0.3 to 3.8 dS m-1 on the vigor and formation of lettuce seedling. The irrigation water of desired ECw was prepared maintaining equivalent proportion of 7:2:1, among Na:Ca:Mg, respectively. All the variables studied were affected by salinity during germination and in the seedling stage, however ECw of 3.8 dS m-1, considered as being of severe agricultural restriction, provided on average 90% of relative germination, 61% of vigor and seedling with 50% growth, permits to classify lettuce as moderately tolerant to salinity during germination and moderately sensitive in the seedling phase.

Sergio B. A., Viana; Pedro D., Fernandes; Hans R., Gheyi.

2001-05-01

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

Scientific Electronic Library Online (English)

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

Tamara Maria, Gomes; Valéria A., Modolo; Tarlei A., Botrel; Ricardo F. de, Oliveira.

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

Science.gov (United States)

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) micromol/L. It accumulated (999 +/- 95) mg As/kg dw when exposed in 320 micromol/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 Km 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. PMID:21793402

Zhang, Xin; Hu, Ying; Liu, Yunxia; Chen, Baodong

2011-01-01

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

International Nuclear Information System (INIS)

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

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Ecophysiological tolerance of duckweeds exposed to copper  

Energy Technology Data Exchange (ETDEWEB)

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

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

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Effects of exogenous abscisic acid on yield, antioxidant capacities, and phytochemical contents of greenhouse grown lettuces.  

Science.gov (United States)

Antioxidants and phytochemicals in vegetables are known to provide health benefits. Strategies that enhance these properties are expected to increase the nutritional values of vegetables. The objective of this research is to assess the effects of exogenous abscisic acid (ABA) on yield, antioxidant capacities, and phytochemical content of lettuces grown in a greenhouse. Red loose leaf lettuce (cv. Galactic) and green loose leaf lettuce (cv. Simpson Elite) were cultivated using a randomized complete block design. Three concentrations of ABA in water [0 (control), 150, 300 ppm] were sprayed on the 30th and 39th days after sowing, and lettuces were harvested on the 46th day. Exogenous ABA significantly decreased yield of green and red lettuces. Total phenolic and total anthocyanin contents in red lettuce treated with ABA were significantly higher than in controls, whereas no significant differences were observed in green lettuce. ABA significantly induced the accumulation of chlorophyll b and total carotenoids in lettuces. The phenolic compounds identified and quantified in red and green lettuces included caffeoyltartaric acid, 5-O-caffeoylquinic acid, dicaffeoyltartaric acid, 3,5-dicaffeoylquinic acid, and quercetin 3-(6''-malonyl)-glucoside. Additionally, cyanidin 3-glucoside, cyanidin 3-(3''-malonoyl)-glucoside, and cyanidin 3-(6''-malonoyl)-glucoside in red lettuces were quantified. No significant effects of ABA on these individual phytochemicals were observed in green lettuces, whereas ABA significantly elevated the content of individual phytochemicals in red lettuces except for 5-O-caffeoylquinic acid. Differences among red lettuces with or without exogenous ABA were visualized on the score plots of principal component analyses. Loading plot indicated that multiple phenolic compounds contributed to the observed differences in red lettuces. PMID:20420437

Li, Zheng; Zhao, Xin; Sandhu, Amandeep K; Gu, Liwei

2010-05-26

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Moderate and high doses of sodium hypochlorite, neutral electrolyzed oxidizing water, peroxyacetic acid, and gaseous chlorine dioxide did not affect the nutritional and sensory qualities of fresh-cut Iceberg lettuce (Lactuca sativa Var. capitata L.) after washing.  

Science.gov (United States)

Besides the traditionally used sodium hypochlorite (20 and 200 mg L(-1)), alternative sanitizers such as peroxyacetic acid (80 and 250 mg L(-1)) and neutral electrolyzed oxidizing water (4.5 and 30 mg L(-1) free chlorine) as well as chlorine dioxide gas (1.54 mg L(-1)) were evaluated for their efficiency in reducing the microbial load of fresh-cut iceberg lettuce. An additional rinsing step with tap water and cooling of the sanitizing solutions, which are obvious for the fresh-cut industry, were not performed within the current study. The high doses of sodium hypochlorite and peroxyacetic acid tested within this study do not conform to the normally used concentrations within the fresh-cut industry. Neutral electrolyzed oxidizing water (30 mg L(-1)), peroxyacetic acid (250 mg L(-1)), and gaseous chlorine dioxide significantly reduced the total aerobic plate count of cut lettuce in comparison with water wash treatments alone. None of the treatments significantly affected the sensory quality of the lettuce, although small color changes were observed after colorimetric measurements. From a nutritional point of view water rinsing significantly decreased the vitamin C (maximum 35%) and phenol (maximum 17%) contents, but did not affect the carotenoid and ?-tocopherol contents. Additional effects caused by adding a sanitizer to the wash water were not observed for vitamin C and phenols. Conversely, washing with 250 mg L(-1) peroxyacetic acid reduced the ?-carotene content by about 30%, whereas using 200 mg L(-1) sodium hypochlorite reduced both the lactucaxanthin and the lutein contents by about 60%. Use of gaseous chlorine dioxide also had an impact on the lutein content (-18%). Furthermore, the ?-tocopherol content was reduced by 19.7 and 15.4% when the two concentrations of neutral electrolyzed oxidizing water were used, respectively. These data represent the situation on day 0. In a next phase, shelf-life studies considering microbial and sensory quality and nutrient content should be conducted. PMID:19371140

Vandekinderen, Isabelle; Van Camp, John; De Meulenaer, Bruno; Veramme, Kim; Bernaert, Nathalie; Denon, Quenten; Ragaert, Peter; Devlieghere, Frank

2009-05-27

51

Removal of faecal bacteria from septage by treating it in a full-scale duckweed-covered pond system.  

Science.gov (United States)

Performance of a full-scale duckweed-covered treatment system in removing faecal bacteria is presented. The system consisted of three ponds in series and received septage from holding tanks. Inflow averaged between 36 m(3) d(-1) in the cold season and 60 m(3) d(-1) in the warm season, resulting in a total hydraulic retention time of 88 and 58 days, respectively. Duckweed (Lemna minor) colonized the ponds in the summer and continued to grow in the cold season. Due to the difficult harvesting process of the duckweed biomass, the investigation of the treatment efficiency was carried out without plant harvesting. The system was monitored for temperature, pH, oxygen, chlorophyll-a, Escherichia coli and Enterococci. Duckweed growth resulted in chlorophyll-a concentration reduction from 924 to 13 ?g L(-1), causing neutral and anoxic conditions in the pond water. A temperature effect was noticed on the E. coli decay coefficient with a decreasing trend along the treatment system. Enterococci always decayed less than E. coli. Differences on decay coefficients and removal efficiencies were not observed between the three ponds for both bacterial types. Effluent quality in terms of E. coli was 489 and 1377 cfu/100 mL, in the warm and the cold seasons, respectively, with average removals of 99.65 ± 1.46% and 99.33 ± 3.03%. Total Enterococci removal was 88.91 ± 23.1% in the warm season and 94.43 ± 24.45% in the cold season, resulting in mean effluent values of 1058 and 1404 cfu/100 mL, respectively. The seasonal differences in total removal efficiencies were insignificant for both bacterial types. PMID:21872385

Papadopoulos, Frantzis H; Tsihrintzis, Vassilios A; Zdragas, Antonios G

2011-12-01

52

Inactivation of feline calicivirus as a surrogate for norovirus on lettuce by electron beam irradiation.  

Science.gov (United States)

Caliciviridae, including norovirus, are considered important sources of human gastroenteritis. As leafy green vegetables are commonly consumed without additional processing, it is important to evaluate interventions to reduce the presence of human pathogens in these products. Feline calicivirus was used as a model for small round structured viruses on lettuce. The lettuce was inoculated by immersion to simulate contamination from irrigation or wash water. The inoculated lettuce was then exposed to electron beam irradiation at various dose levels to determine survival. The D??-value of the calicivirus on lettuce was determined to be 2.95 kGy. Irradiation to reduce bacterial pathogens on cut lettuce could also reduce the risk associated with small round structured viruses on lettuce. PMID:21902919

Zhou, Fanghong; Harmon, Karen M; Yoon, Kyoung-Jin; Olson, Dennis G; Dickson, James S

2011-09-01

53

Arsenic uptake and speciation in the rootless duckweed Wolffia globosa.  

Science.gov (United States)

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

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

2009-01-01

54

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

Directory of Open Access Journals (Sweden)

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

Glauco E. P. Cortez

2009-08-01

55

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

Scientific Electronic Library Online (English)

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

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

2009-08-01

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

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

Dalva Paulus

2010-03-01

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

Scientific Electronic Library Online (English)

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

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

2010-03-01

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

Scientific Electronic Library Online (English)

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

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

59

Browning control of fresh-cut lettuce by phytoncide treatment.  

Science.gov (United States)

Phytoncide essential oil derived from pine leaves was applied for the control of enzymatic browning of fresh-cut lettuce. Changes in the browning characteristics of cut lettuce treated with phytoncide in an water or ethanol solution (1%, v/v) at 10°C were investigated for 12days at 4°C. Other samples dipped in distilled water or 95% ethanol were used as the controls. The samples treated with phytoncide in an ethanol solution showed significantly higher L* values and lower a* values, ?E values, browning index, phenolic compounds, and enzyme activities (PPO, POD, PAL) related to browning. The samples dipped in distilled water showed the opposite tendency. On the basis of changes in the browning characteristics, anti-browning effects of each treatment, phytoncide in an ethanol solution was the most effective treatment applied. These results suggest that phytoncide treatment could be used as an effective method for controlling enzymatic browning in fresh-cut lettuce. PMID:24767043

Kim, Do-Hee; Kim, Han-Bit; Chung, Hun-Sik; Moon, Kwang-Deog

2014-09-15

60

The duckweed Wolffia globosa as an indicator of heavy metal pollution: Sensitivity to Cr and Cd.  

Science.gov (United States)

The potential of Wolffia globosa, a profusely occurring rootless duckweed, was evaluated as an indicator of metal pollution in the water bodies. Plants of W. globosa were cultured in 3% Hoagland's nutrient medium which was supplemented with 0.05, 0.1, 1.0 and 2.0 mg/L of Cr and Cd. Plants showed substantial accumulation of both the metals at lowest concentrations. For example, at 0.05 ppm, the concentration factor (Cf) value for Cr was significantly higher (5616) than for Cd (1018). A high level of tolerance was shown by the plants to both Cr and Cd. The results show that the plants are sensitive to the variations in metal concentration and are capable of high metal enrichment at very low ambient concentration of the metals. This information may be useful for detecting metals in the water. PMID:24221234

Grag, P; Chandra, P

1994-01-01

 
 
 
 
61

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

Science.gov (United States)

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

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

2014-01-01

62

Efeito de velocidades de rebaixamento do nível freático em diferentes períodos de desenvolvimento da cultura da alface / Effect of water table drawdown velocities in different stages of lettuce crop  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Através deste trabalho objetivou-se determinar os efeitos do encharcamento do solo nas variáveis fenológicas e na produtividade da cultura da alface, identificar o estádio fenológico em que ocorre a maior diminuição da produtividade e obter uma relação entre a produtividade relativa da cultura e o í [...] ndice diário de estresse. O delineamento experimental adotado foi inteiramente casualizado, arranjado em esquema fatorial [(3x4)+1], com 3 repetições. Os tratamentos consistiram do período de inundação (12, 22 e 32 DAT), de velocidades de rebaixamento do nível freático (30 cm em 24, 48, 72 e 96 horas) e uma testemunha, na qual não foi aplicado estresse por elevação do lençol freático. A alface apresentou-se como cultura sensível ao encharcamento; entretanto, não foi possível se definir um valor para o coeficiente de drenagem pois, mesmo com a maior velocidade de rebaixamento testada, ocorreu decréscimo de cerca de 50% da produção. Dentre os três períodos nos quais o estresse causado pela elevação do nível freático foi aplicado, o primeiro foi o que ocasionou maiores perdas. A produtividade das plantas de alface apresentou correlação linear negativa com o índice diário de estresse (IDS). Abstract in english The work had the objectives of determining the effect of water table drawdown velocities on the growth and yield of lettuce crop in a flooded soil, identifying the stage of the crop cycle with the highest reduction in the productivity and obtaining a relation between the crop relative productivity a [...] nd the daily stress index. The statistical experimental design was completely randomized in factorial scheme [(3 x 4) + 1], with three replications. The water table was lowered at 3 stages of the crop cycle (12, 22 and 32 days after the transplanting), four drawdown velocities (30 cm during 24, 48, 72 and 96 h) and a 13 treatment in which stress was not applied with the elevation of the water table. The lettuce presented as a sensible crop to the water-logging, although, it was not possible to define a value for the drainage coefficient because the highest drawdown velocity tested presented 50% of loss in the yield. Among the three crop stages in witch the stress caused by the water table elevation was applied, the first one caused the highest loss in the yield. The relative yield of lettuce plant had a negative linear relation with the daily stress index.

Rafael, Mingoti; Pablo A. N., Flecha; Sérgio N., Duarte; Décio E., Cruciani.

63

Efeito de velocidades de rebaixamento do nível freático em diferentes períodos de desenvolvimento da cultura da alface / Effect of water table drawdown velocities in different stages of lettuce crop  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Através deste trabalho objetivou-se determinar os efeitos do encharcamento do solo nas variáveis fenológicas e na produtividade da cultura da alface, identificar o estádio fenológico em que ocorre a maior diminuição da produtividade e obter uma relação entre a produtividade relativa da cultura e o í [...] ndice diário de estresse. O delineamento experimental adotado foi inteiramente casualizado, arranjado em esquema fatorial [(3x4)+1], com 3 repetições. Os tratamentos consistiram do período de inundação (12, 22 e 32 DAT), de velocidades de rebaixamento do nível freático (30 cm em 24, 48, 72 e 96 horas) e uma testemunha, na qual não foi aplicado estresse por elevação do lençol freático. A alface apresentou-se como cultura sensível ao encharcamento; entretanto, não foi possível se definir um valor para o coeficiente de drenagem pois, mesmo com a maior velocidade de rebaixamento testada, ocorreu decréscimo de cerca de 50% da produção. Dentre os três períodos nos quais o estresse causado pela elevação do nível freático foi aplicado, o primeiro foi o que ocasionou maiores perdas. A produtividade das plantas de alface apresentou correlação linear negativa com o índice diário de estresse (IDS). Abstract in english The work had the objectives of determining the effect of water table drawdown velocities on the growth and yield of lettuce crop in a flooded soil, identifying the stage of the crop cycle with the highest reduction in the productivity and obtaining a relation between the crop relative productivity a [...] nd the daily stress index. The statistical experimental design was completely randomized in factorial scheme [(3 x 4) + 1], with three replications. The water table was lowered at 3 stages of the crop cycle (12, 22 and 32 days after the transplanting), four drawdown velocities (30 cm during 24, 48, 72 and 96 h) and a 13 treatment in which stress was not applied with the elevation of the water table. The lettuce presented as a sensible crop to the water-logging, although, it was not possible to define a value for the drainage coefficient because the highest drawdown velocity tested presented 50% of loss in the yield. Among the three crop stages in witch the stress caused by the water table elevation was applied, the first one caused the highest loss in the yield. The relative yield of lettuce plant had a negative linear relation with the daily stress index.

Rafael, Mingoti; Pablo A. N., Flecha; Sérgio N., Duarte; Décio E., Cruciani.

2006-03-01

64

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

Scientific Electronic Library Online (English)

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

JULIANA, RUIZ.

2011-12-01

65

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

Directory of Open Access Journals (Sweden)

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.

Sujata A. Sirsat

2013-11-01

66

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

International Nuclear Information System (INIS)

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

67

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

Science.gov (United States)

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

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

2014-01-01

68

Quantification of nitrification and denitrification rates in algae and duckweed based wastewater treatment systems.  

Science.gov (United States)

Nitrification and denitrification rates at three different depths (0.1, 0.45 and 0.9m from the water surface) in two series of four algae and duckweed based waste stabilisation ponds (ABPs and DBPs) were measured using nitrate reduction techniques in laboratory batch incubations. The effects of temperature and BOD5 loading were investigated. In situ measurements over the ponds' depths were also done for confirmation of laboratory results. Higher dissolved oxygen (DO) concentrations in ABPs, especially during the warm season, favoured higher nitrification in ABPs over DBPs. Organic surface loading also affected the rate of nitrification in the ponds. Nitrification rates did not increase along the treatment line despite the decrease in organic matter content. Adsorption of nitrifiers to available suspended particles and subsequent sedimentation was assumed to be the main reason for the similar nitrification rates in most ponds. In both systems, the presence of DO in the water column resulted in very low denitrification rates (5-45 mg-N m(-2)d(-1)). Higher denitrification rates (160-560 mg-N m(-2)d(-1)) were measured in the sediments when anoxic conditions prevailed in the overlaying water. The absence of nitrite or nitrate accumulation suggested sufficient nitrite and nitrate diffusion within the water column to allow full denitrification. The nitrification and denitrification rates in both systems were higher at high temperature. The range of nitrogen loss via denitrification in ABPs and DBPs corresponded to 15-25% of total influent nitrogen. PMID:15176742

Zimmo, O R; van der Steen, N P; Gijzen, H J

2004-03-01

69

Ethylene evolution and endo-b-mannanase activity during lettuce seed germination at high temperature  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 aminoethoxyviny...

Nascimento Warley Marcos; Cantliffe Daniel James; Huber Donald John

2004-01-01

70

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

Directory of Open Access Journals (Sweden)

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

B. Indarsih

2012-08-01

71

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

Science.gov (United States)

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.

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

72

Agronomic efficiency of intercropping tomato and lettuce.  

Science.gov (United States)

Four experiments were carried out at the São Paulo State University, Brazil, with the aim of determining the agronomic viability of intercropping tomato and lettuce, under greenhouse conditions. The studied intercropping systems were established by transplanting lettuce at 0, 10, 20 and 30 days after transplanting (DAT) tomato and by transplanting tomato at 0, 10, 20 and 30 DAT lettuce. Intercropped tomato and lettuce were evaluated during two seasons and compared to their sole cropping. The experimental design was a randomized complete block with nine treatments. The productivity and the classification of the tomato fruits were not influenced by having lettuce intercropped with it, but lettuce production was lowered when tomato was intercropped with it. The longer the delay in lettuce transplanting, the greater the reduction in its productivity. There was an effect of cropping season on the extent of the agronomic advantage of intercropping over sole cropping. In the first cropping season, intercropping established by transplanting lettuce during the interval between 30 days before up to 20 DAT tomato yielded land use efficiency (LUE) indices of 1.63 to 2.22. In the second period, intercropping established with the transplanting of lettuce up to 30 days before tomato yielded LUE indices of 1.57 to 2.05. PMID:21861045

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

2011-09-01

73

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

Scientific Electronic Library Online (English)

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

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

2011-04-01

74

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

Science.gov (United States)

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

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

2014-08-01

75

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

Scientific Electronic Library Online (English)

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

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

2012-03-01

76

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

Directory of Open Access Journals (Sweden)

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

Dalva Paulus

2012-03-01

77

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

Scientific Electronic Library Online (English)

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

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

78

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

Directory of Open Access Journals (Sweden)

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

M.U. Ahammad

2003-01-01

79

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

Science.gov (United States)

Mirafiori lettuce big vein virus (MiLBVV) and lettuce big vein associated virus (LBVaV) were found in association with big vein disease of lettuce in Iran. Analysis of part of the coat protein (CP) gene of Iranian isolates of LBVaV showed 97.1-100 % nucleotide sequence identity with other LBVaV isolates. Iranian isolates of MiLBVV belonged to subgroup A and showed 88.6-98.8 % nucleotide sequence identity with other isolates of this virus when amplified by PCR primer pair MiLV VP. The occurrence of both viruses in lettuce crop was associated with the presence of resting spores and zoosporangia of the fungus Olpidium brassicae in lettuce roots under field and greenhouse conditions. Two months after sowing lettuce seed in soil collected from a lettuce field with big vein affected plants, all seedlings were positive for LBVaV and MiLBVV, indicating soil transmission of both viruses. PMID:24293824

Alemzadeh, E; Izadpanah, K

2012-12-01

80

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

Scientific Electronic Library Online (English)

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

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

 
 
 
 
81

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

Directory of Open Access Journals (Sweden)

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

S.R. Marchi

2009-06-01

82

Antimicrobial activity of plant essential oils against Escherichia coli O157:H7 and Salmonella on lettuce.  

Science.gov (United States)

Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce-wash, the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Lettuce pieces were inoculated with a five-strain cocktail of Escherichia coli O157:H7 or Salmonella enterica (5 log CFU/g) and then immersed in a treatment solution containing 5 ppm free chlorine, cinnamaldehyde, or Sporan(®) (800 and 1000 ppm) alone or in combination with 200 ppm acetic acid (20%) for 1 min. Treated leaves were spin-dried and stored at 4°C. Samples were taken to determine the surviving populations of E. coli O157:H7, Salmonella, total coliforms, mesophilic and psychrotrophic bacteria, and yeasts and molds during the 14-day storage period. The effect of treatments on lettuce color and texture was also determined. Cinnamaldehyde-Tween (800 ppm, 800T) reduced E. coli O157:H7 by 2.89 log CFU/g (p0.05) to those treated with chlorine and control (water). The texture and the color of iceberg and romaine lettuce treated with essential oils were not different from the control lettuce after 14 days of storage. This study demonstrates the potential of Sporan(®) and cinnamaldehyde as effective lettuce washes that do not affect lettuce color and texture. PMID:23256843

Yossa, Nadine; Patel, Jitendra; Millner, Patricia; Ravishankar, Sadhana; Lo, Y Martin

2013-01-01

83

A dynamic model for nitrogen-stressed lettuce.  

Science.gov (United States)

A previously developed dynamic lettuce model, designed to predict growth and nitrate content under the normal range of glasshouse environmental conditions, has been extended to cover high nitrogen-stress situations. Under severe shortage of nitrogen, lettuce has been observed to grow at a very slow rate, as well as to have abnormally low water content, low reduced-nitrogen content and negligible nitrate content. The new model mimics these observations by adding to the original model a storage compartment for 'excess' carbon. The resulting model has three compartments: (1) 'vacuole', where the soluble non-structural material is stored, and the nitrate : carbon ratio may vary as needed to maintain a constant osmotic potential; (2) 'structure', a metabolically active compartment with fixed chemical composition; and (3) 'excess-carbon', which serves as a long-term storage of 'waterless' carbohydrates. Simulations with the model illustrate its ability to predict the effect of light, temperature and nitrogen in the nutrient solution on the long-term growth and composition of lettuce. They also illustrate the effects of plant size, and the associated relative growth rate, on the characteristic times of transient responses resulting from step changes in the environment. PMID:12714361

Seginer, Ido

2003-05-01

84

Growth, yield and quality of tomatoes (Lycopersicon Esculentum Mill.)and lettuce (Lactuca Sativa L.) as affected by gel-polymer soil amendment and irrigation management  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Tomato and lettuce are amongst the most important fresh vegetables used in South Africa. However, growth, yield and quality of tomato and lettuce are constrained by water shortage and poor productivity of sandy soil. In South Africa, large parts of the agricultural land are in a semi-arid region and water is becoming scarcer and more costly. Recognizing the fundamental importance of water-holding amendments like gel-polymers to enhance water use efficiency and soil physical properties, this s...

Maboko, Martin Makgose

2006-01-01

85

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

Science.gov (United States)

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

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

2014-12-01

86

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

International Nuclear Information System (INIS)

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

87

Alteration of root growth by lettuce, wheat, and soybean in response to wear debris from automotive brake pads.  

Science.gov (United States)

Brakes from motor vehicles release brake pad wear debris (BPWD) with increased concentrations of heavy metals. Germination and root-elongation assays with lettuce, wheat, and soybean were used to provide an initial evaluation of the phytotoxicity of either a water extract of BPWD or BPWD particulates. In terms of germination, the only effect observed was that lettuce germination decreased significantly in the BPWD particulate treatment. Lettuce and wheat showed decreased root length and root-elongation rate in the presence of the BPWD particulates, whereas lettuce produced a significantly greater number of lateral roots in response to BPWD extract. There was no significant effect of either BPWD treatment on soybean root elongation or lateral roots. Treatment with BPWD extracts or particulates caused significant alterations in the bending pattern of the plant roots. These initial results suggest that BPWD may have effects on the early growth and development of plants. PMID:24957180

Dodd, Misty D; Ebbs, Stephen D; Gibson, David J; Filip, Peter

2014-11-01

88

Assessment of a full-scale duckweed pond system for septage treatment.  

Science.gov (United States)

Environmental conditions and wastewater treatment performance in a full-scale duckweed pond system are presented. The treatment system consisted of three stabilization ponds in series and was fed with septage. Vacuum trucks pumped the septage from residential holding tanks and discharged it to the system daily. The inflow rates averaged 36 m3 d(-1) in the cold season and 60 m3 d(-1) in the warm season. Duckweed (Lemna minor) colonized the ponds in the warm months and survived during the cold season. Because of the difficult process for harvesting the duckweed biomass, the investigation of the treatment efficiency was carried out without plant harvesting. Samples were collected from the vacuum trucks and from the exit of each pond and were analysed for physicochemical and microbiological parameters over a period of 12 months. The results showed that the duckweed mat suppressed algal biomass, which in turn led to anoxic and neutral pond conditions. On an annual basis, the duckweed system sufficiently removed BOD5 (94%), NH4+ (72%) and E. coli (99.65%), with lower removal of TSS (63%) and Enterococci (91.76%). A slight increase (1.1%) was recorded for o-PO4(3-). Between the two sampling seasons, BOD5 and TSS removal efficiencies were higher in the cold season with the longer retention time. Similar removal values in the warm and the cold season were found for nutrients and bacteria. These findings indicate that BOD5 and TSS removals are less temperature-dependent at higher retention times, while ammonia nitrogen and bacterial removals are substantially influenced by temperature as well as retention time. PMID:21879554

Papadopoulos, F H; Tsihrintzis, V A

2011-01-01

89

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  

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

S.R. Marchi

2011-03-01

90

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

International Nuclear Information System (INIS)

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

91

Stimulating productivity of hydroponic lettuce in controlled environments with triacontanol  

Science.gov (United States)

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

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

1987-01-01

92

Use of duckweed (Lemna disperma) to assess the phytotoxicity of the products of Fenton oxidation of metsulfuron methyl.  

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Because of pressure on water supplies world-wide, there is increasing interest in methods of remediating contaminated ground waters. However, with some remediation processes, the breakdown products are more toxic than the original contaminant. Organic matter and salinity may also influence degradation efficiency. This study tested the efficiency of Fenton oxidation in degrading the sulfonylurea herbicide metsulfuron methyl (MeS), and tested the reaction products for phytotoxicity with the Lemna (duckweed) bioassay. The efficiency of degradation by Fenton's reagent (Fe(2+)=0.09 mM; H(2)O(2)=1.76 mM, 4h) decreased with increasing initial MeS concentration, from 98% with 5 mg/L MeS, to 63% with 70 mg/L MeS. Addition of NaCl (10mM) and organic matter (humic acid at 0.2 and 2.0mg C/L as Total Organic Carbon) reduced the efficiency of degradation at low initial MeS concentrations (5 and 10 mg/L), but had no effect at high concentrations. The residual Fenton's reagent after Fenton's oxidation was toxic to Lemna. After removal of residual iron and H(2)O(2), the measured toxicity to Lemna in the treated samples could be explained by the concentrations of MeS as measured by HPLC/UV detection, so there was no evidence of additional toxicity or amelioration due to the by-products or formulation materials. PMID:22776711

Abdul, Javeed M; Colville, Anne; Lim, Richard; Vigneswaran, Saravanamuthu; Kandasamy, Jaya

2012-09-01

93

Sources of Verticillium dahliae affecting lettuce.  

Science.gov (United States)

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

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

2012-11-01

94

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

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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.

Zuzanna Witkowska

2012-01-01

95

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

Science.gov (United States)

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 × 10? to 1.7 × 10? 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

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

2012-05-01

96

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Um estudo conduzido na Fazenda Experimental Maricopa (33º04'07" N; 111º57'18" W), pertencente à Universidade do Arizona, USA, nos anos agrícolas de 1996/97 e 1997/98, objetivou determinar o uso de água e derivar coeficientes de cultura (Kc) da alface de cabeça irrigada por gotejamento subsuperficial [...] e cultivada em lisímetros de pesagem intermitente. O período de medições, expresso em graus-dia acumulados, variou de 480 a 1100 ºC-dia em 96/97 e de 439 a 1098 ºC-dia em 97/98. Esses intervalos corresponderam à segunda metade do ciclo da cultura, sendo que até a colheita somou-se uma média de 1100 ºC-dia. Os lisímetros eram pesados periodicamente e o balanço hídrico revelou um consumo médio de 117 mm, naqueles períodos. O Kc basal foi relacionado com o acúmulo de graus-dia através de regressão múltipla, seguindo um modelo dado por uma série seno de Fourier, com até seis coeficientes. As curvas de Kc foram determinadas com base nos métodos de Hargreaves, FAO Penman e FAO Penman-Monteith, para cálculo da ETo e comparadas por aquela gerada pelo programa AZSCHED (AriZona SCHEDuling) de manejo da irrigação. Valores máximos de Kc estimados foram 0,88 (método de Hargreaves), 0,80 (FAO Penman) e 0,81 (FAO Penman-Monteith) no intervalo de 1000 a 1050 ºC dia, inferiores a 1,01 em 1150 ºC dia, que é o máximo Kc previsto pelo programa AZSCHED. Abstract in english A two year field study (1996/97 and 1997/98 growing seasons) was carried out at the Maricopa Agricultural Center (33º04'07" N; 111º57'18" W) of the University of Arizona, USA, to investigate the water use and to derive Kc's for subsurface drip-irrigated head lettuce grown in small weighable lysimete [...] rs. Measurement periods ranged from 480 to 1100 ºC-day (96/97) and from 439 to 1098 ºC-day (97/98). These intervals corresponded essentially to the second half of the crop cycle which amounted to a 1100 ºC-day, on average. The lysimeters were weighed periodically and the computation of the water balance revealed an average water use of 117 mm. Basal crop Kc was expressed as a function of cumulative growing degree days following a multiple linear regression procedure in which the data were fitted with a Fourier sine series model with up to six coefficients. Two-year Kc curves were obtained based on the Hargreaves, FAO Penman and FAO Penman-Monteith equations and compared to the AZSCHED (AriZona SCHEDuling) irrigation package. Predicted Kc peaked 0.88, 0.80 and 0.81 with the Hargreaves, FAO Penman, FAO Penman-Monteith equations, respectively, in the range of 1000 to 1050 ºC-day, in contrast to AZSCHED which predicted the peak Kc to be 1.01 at 1150 ºC-day.

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

97

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

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

Qian Chen

2012-08-01

98

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

Science.gov (United States)

The internalisation potential of Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella enterica subsp. enterica serovar Typhimurium in lettuce was evaluated using seedlings grown in vermiculite in seedling trays as well as hydroponically grown lettuce. Sterile distilled water was spiked with one of the four human pathogenic bacteria (10(5) CFU/mL) and used to irrigate the plants. The potential for pathogen internalisation was investigated over time using light microscopy, transmission electron microscopy and viable plate counts. Additionally, the identities of the pathogens isolated from internal lettuce plant tissues were confirmed using polymerase chain reaction with pathogen-specific oligonucleotides. Internalisation of each of the human pathogens was evident in both lettuce seedlings and hydroponically grown mature lettuce plants. To our knowledge, this is the first report of S. aureus internalisation in lettuce plants. In addition, the levels of background microflora in the lettuce plants were determined by plate counting and the isolates identified using matrix-assisted laser ionisation-time of flight (MALDI-TOF). Background microflora assessments confirmed the absence of the four pathogens evaluated in this study. A low titre of previously described endophytes and soil inhabitants, i.e., Enterobacter cloacae, Enterococcus faecalis, Lysinibacillus fusiformis, Rhodococcus rhodochrous, Staphylococcus epidermidis and Staphylococcus hominis were identified. PMID:23708570

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

2013-06-01

99

Effect of electric pulse charged to culture soil on improvement of nutritional soil condition and growth of lettuce (Lactuca sative L.  

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Full Text Available This study is intended to measure variations of nutritional soil condition and mass spectrometric patterns to describe the specific effects of electric pulse charged to culture soil which induced an increase of lettuce growth. In a previous study, lettuce cultivated in an electrically pulsed culture soil (EPCS grew more actively than those in a conventional culture soil (CCS. Lettuce growth increased about 20% more in EPCS than CCS during cultivated for 21 days in this study. Content of nutrient salts and minerals varied in CCS and EPCS when assayed after the period of lettuce cultivation. Ammonium content in CCS was higher than that in EPCS but nitrate content was opposite of the ammonium. Inorganic N-compounds in EPCS was about 2.5 times higher than that in CCS. Content of phosphate in CCS increased greatly by lettuce cultivation but was about 2 times lower than that in EPCS. Contents of minerals in EPCS were relatively higher than those in CCS excepting Fe. Patterns of chromatography and mass spectrometry for water soluble compounds extracted from lettuces cultivated in EPCS were considerably different from those in CCS. Conclusively, electric pulse caused increased lettuce growth, improved nutritional soil conditions, and varied mass spectrometric patterns.

Jun Young Yi

2012-11-01

100

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

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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.

P?czu?a W.

2014-01-01

 
 
 
 
101

Clonal expansion of Verticillium dahliae in lettuce.  

Science.gov (United States)

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 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

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

2014-06-01

102

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

International Nuclear Information System (INIS)

Ionizing radiation effectively reduces the number of common microbial pathogens in fresh produce. However, the efficacy of the process for pathogens internalized into produce tissue is unknown. The objective of this study was to understand gamma irradiation of lettuce leaf structure exposed in a 137Cs irradiator using MCNP. The simulated 137Cs irradiator is a self-shielded device, and its geometry and sources are described in the MCNP input file. When the irradiation chamber is filled with water, lower doses are found at the center of the irradiation volume and the dose uniformity ratio (maximum dose/minimum dose) is 1.76. For randomly oriented rectangular lettuce leaf segments in the irradiation chamber, the dose uniformity ratio is 1.25. It shows that dose uniformity in the Cs irradiator is strongly dependent of the density of the sample. To understand dose distribution inside the leaf, we divided a lettuce leaf into a low density (flat) region (0.72 g/cm3) and high density (rib) region (0.86 g/cm3). Calculated doses to the rib are 61% higher than doses to the flat region of the leaf. This indicates that internalized microorganisms can be inactivated more easily than organisms on the surface. This study shows that irradiation can effectively reduce viable microorganism internalized in lettuce. (author)

103

Partial aphid resistance in lettuce negatively affects parasitoids.  

Science.gov (United States)

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

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

2014-10-01

104

Effect of the Municipal Garbage on the Growth of Lettuce  

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Full Text Available Municipal Garbage (MG as a plant nutrient supply was evaluated. Some of the garbage was collected from Hail city, Kingdom of Saudi Arabia. The garbage was fermented partially after removing its contents of stones and metals. Lettuce plants were transplanted in five greenhouse pot experiments. In the first, a portion of the MG was mixed with a sandy soil at either 1, 2 or 3% before the transplanting. In the second, a portion of the MG was mixed with hydrochloric acid 0.1 Nat ratio of 1:2 for 15 days then extracted. The solid extracted portion was mixed with the sandy soil at 1, 2 , or 3%. A week after lettuce transplanting, a foliar spray technique was used to spray the HCl extract. In third and fourth experiments, the Coca Cola and the distilled water as extractants were used similarly to the second experiment. The fifth experiment was fertilized using the conventional rate of NPK fertilization ( control. The lettuce plants were harvested after two months from the experiment initiation then soil pH and total soluble salts were determined in 1:2.5 soil water extract. The pH and total soluble salt values among the treatments were not significant. Growth parameters such as the total fresh weight, shoot fresh weight, shoot dry weight and the dry matter percentage were determined. The results of the former three parameters increased as the rate of MG increased under the condition of the first four experiments. In addition, these parameters were great under the MG experiments in comparison to the control experiment. The dry matter percentages using 2% rate of MG were the greatest under all experiments except the Coca Cola experiment. This percentages increased as the rate of MG increased under the Coca Cola experiment condition. All of the growth parameters were the greatest under the condition of distilled water experiment among all of the experiments. The results of the study encourage using the water extract of MG as a source for plant nutrients and the extracted portion as a soil conditioner.

K.N. Al-Redhaiman

2003-01-01

105

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

International Nuclear Information System (INIS)

This study is a continuation of similar studies conducted by Easton and Murphy (1993) and Loehle (1990). The objectives of these studies are to: (1) assess the toxicity of the water-soluble constituents of soil in a seepline adjacent to the F-Area Seepage Basins and (2) evaluate the effectiveness of rainwater movements in reducing the toxicity of the soil. Soils from the F-Area seepline that were found to inhibit lettuce seed germination and radical elongation in 1990 were not found to be significantly different from soils from an uncontaminated control site in this test. After six washings of the soil, the toxicity of the leachate was comparable to that of de-ionized water. This indicates that natural water movements may have rendered the F-Area seepline soils less toxic to lettuce seedlings than in previous tests

106

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

Scientific Electronic Library Online (English)

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

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

107

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

Scientific Electronic Library Online (English)

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

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

2011-03-01

108

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

Science.gov (United States)

Arbuscular mycorrhizal fungi (AMF) develop symbiotic associations with plants roots. These associations are very common in the natural environment and can provide a range of benefits to the host plant. AMF improve nutrition, enhance resistance to soil-borne pests and disease, increase resistance to drought and tolerance to heavy metals, and contribute to a better soil structure. However, agricultural intensive managements, such as the use of mineral fertilizes, pesticides, mouldboard tillage, monocultures and use of non-mycorrhizal crops, are detrimental to AMF. As a consequence, agroecosystems are impoverished in AMF and may not provide the full range of benefits to the crop. Organic farming systems may be less unfavourable to AMF because they exclude the use of water-soluble fertilisers and most pesticides, and generally they plan diverse crop rotations. The AMF develop the most common type of symbiosis in nature: about 90% of the plants are mycorrhizal and many agricultural crops are mycorrhizal. One of more mycorrhizal crops is lettuce, that is very widespread in intensive agricultural under greenhouse. Therefore, cultivated lettuce is know to be responsive to mycorrhizal colonization which can reach 80% of root length and contribute to phosphorus and nitrogen absorption by this plant specie. For this work four different lettuce cultivars (Romana, Milanesa, Grande Lagos and Escarola) were used to study mycorrhization under organic agricultural system, supplying compost from agricultural waste (1 kg m-2) as background fertilization for all plots, red guano as phosphorus source (75 U ha-1 and 150 U ha-1 of P2O5), lupine flour as nitrogen source (75 and 150 U/ha of N) and a combination of both. Lettuce plants were cultivated under greenhouse and after two months of growing, plants were harvested and dried and fresh weight of lettuce roots and shoots were evaluated. The number of spores, percentage of colonization, total mycelium and glomalin content were also evaluated as mycorrhizal parameters. The results showed a different response to mycorrhization of the four lettuce Cvs. In general, mycorrhized lettuce plants had a better response to lower level of nitrogen and phosphorus sources.

Scotti, Riccardo; Seguel, Alex; Cornejo, Pablo; Rao, Maria A.; Borie, Fernando

2010-05-01

109

Induction of betacyanin formation in Chenopodium album cell cultures by co-cultivation with the duckweed Wolffia arrhiza.  

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Cells of Chenopodium album and whole plants of the duckweed Wolffia arrhiza were cocultivated. In the presence of Wolffia arrhiza the synthesis of a red-violet pigment (betacyanin) was induced in several cells or cell clusters of Chenopodium album in the light. The exchange of solutes through the liquid phase was necessary for the induction of pigment formation. The red-violet cells could be selected and subcultivated resulting in a red callus. A reddish cell suspension was obtained in liquid culture in the presence of the duckweeds. PMID:24193767

Rudat, A; Ehwald, R

1994-02-01

110

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

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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.

Sang-Mo Kang

2012-07-01

111

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

Scientific Electronic Library Online (English)

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

Ángel, Canales-Gutiérrez.

2010-07-01

112

Characterization of photosynthetically active duckweed (Wolffia australiana) in vitro culture by Respiration Activity Monitoring System (RAMOS).  

Science.gov (United States)

The feasibility of oxygen transfer rate (OTR) measurement to non-destructively monitor plant propagation and vitality of photosynthetically active plant in vitro culture of duckweed (Wolffia australiana, Lemnaceae) was tested using Respiration Activity Monitoring System (RAMOS). As a result, OTR proofed to be a sensitive indicator for plant vitality. The culture characterization under day/night light conditions, however, revealed a complex interaction between oxygen production and consumption, rendering OTR measurement an unsuitable tool to track plant propagation. However, RAMOS was found to be a useful tool in preliminary studies for process development of photosynthetically active plant in vitro cultures. PMID:17450327

Rechmann, Henrik; Friedrich, Andrea; Forouzan, Dara; Barth, Stefan; Schnabl, Heide; Biselli, Manfred; Boehm, Robert

2007-06-01

113

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

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

Indarsih, B.; Tamsil, M. H.

2012-01-01

114

Production of iceberg lettuce using mulches  

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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.

Verdial Marcelo Fontanetti

2001-01-01

115

Use of Propolis in the Sanitization of Lettuce  

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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.

Xesús Feás

2014-07-01

116

Use of propolis in the sanitization of lettuce.  

Science.gov (United States)

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. PMID:25007823

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

2014-01-01

117

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

Scientific Electronic Library Online (English)

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

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

2013-09-01

118

Effect of different washing procedures on phenolic metabolism of shredded, packaged iceberg lettuce during storage.  

Science.gov (United States)

Different washing treatments applying chlorinated, ozonated, and tap water were examined for their effect on the phenolic metabolism of minimally processed iceberg lettuce (Lactuca sativa L.) during storage in consumer-sized bags at 4 degrees C for up to 9 days. To eliminate problems associated with raw material inhomogeneity, processing was conducted on a pilot-plant scale under operating conditions of industrial practice. Inherent product heterogeneity caused by diverse lettuce leaf tissues was compensated for by pooling large-sized samples, and frequent sampling ensured significant data about the activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD), as well as the contents of caffeic acid derivatives over storage time. In the homogeneous lettuce samples, specific responses caused by different washing procedures were detectable. PAL activity in the samples increased for up to 5-8 days of storage. Compared to tap and ozonated water, the use of chlorinated water (100-200 mg/L free chlorine) for washing trimmed heads or shredded lettuce significantly reduced PAL activity and the concomitant rise of 3,5-di-O-caffeoylquinic acid (isochlorogenic acid isomer) concentrations. The phenolic acids O-caffeoyltartaric (caftaric acid), di-O-caffeoyltartaric (chicoric acid), 5-O-caffeoylquinic (chlorogenic acid isomer), and O-caffeoylmalic were less influenced by different washing treatments. Individual contents either were constant or decreased during storage. Additionally, the novel finding of a further caffeic acid isomer, tentatively identified as meso-di-O-caffeoyltartaric acid, is reported. PPO and POD activities were less affected by different washing treatments and thus were less suitable physiological indicators of stress reactions triggered by alternative processing. PMID:15537312

Baur, Sascha; Klaiber, Ralph G; Koblo, Arjuna; Carle, Reinhold

2004-11-17

119

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

Scientific Electronic Library Online (English)

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

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

120

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

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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.

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

 
 
 
 
121

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

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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.

K. SOWJANYA SREE

2014-06-01

122

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

International Nuclear Information System (INIS)

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

123

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

International Nuclear Information System (INIS)

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

124

Nutrient recovery from domestic wastewater using a UASB-duckweed ponds system.  

Science.gov (United States)

The pilot-scale wastewater treatment system used in this study comprised a 40-l UASB reactor (6-h HRT) followed by three duckweed ponds in series (total HRT 15 days). During the warm season, the treatment system achieved removal values of 93%, 96% and 91% for COD, BOD and TSS, respectively. Residual values of ammonia, TKN and total phosphorus were 0.41 mg N/l, 4.4 mg N/l and 1.11 mg P/l, with removal efficiencies of 98%, 85% and 78%, respectively. The system achieved 99.998% faecal coliform removal during the warm season with final effluent containing 4 x 10(3) cfu/100 ml. During the winter, the system was efficient in removing COD, BOD and TSS but not nutrients. The system was deficient in the removal of faecal coliforms during the winter, producing effluent with 4.7 x 10(5) cfu/100 ml. During the warm season, the N removal consisted of 80% by plant uptake, 5% by sedimentation and 15% unaccounted for. A duckweed production rate of 33 t dry matter per hectare per 8 months was achieved. PMID:16713255

El-Shafai, Saber A; El-Gohary, Fatma A; Nasr, Fayza A; van der Steen, N Peter; Gijzen, Huub J

2007-03-01

125

Phytotoxicity testing of lysimeter leachates from aided phytostabilized Cu-contaminated soils using duckweed (Lemna minor L.).  

Science.gov (United States)

Aided phytostabilization of a Cu-contaminated soil was conducted at a wood preservation site located in southwest France using outdoor lysimeters to study leaching from the root zone and leachate ecotoxicity. The effects of Cu-tolerant plants (Agrostis gigantea L. and Populus trichocarpa x deltoides cv. Beaupré) and four amendments were investigated with seven treatments: untreated soil without plants (UNT) and with plants (PHYTO), and planted soils amended with compost (OM, 5% per air-dried soil weight), dolomitic limestone (DL, 0.2%), Linz-Donawitz slag (LDS, 1%), OM with DL (OMDL), and OM with 2% of zerovalent iron grit (OMZ). Total Cu concentrations (mgkg(-1)) in lysimeter topsoil and subsoil were 1110 and 111-153, respectively. Lysimeter leachates collected in year 3 were characterized for Al, B, Ca, Cu, Fe, Mg, Mn, P, K and Zn concentrations, free Cu ions, and pH. Total Cu concentration in leachates (mgL(-1)) ranged from 0.15±0.08 (LDS) to 1.95±0.47 (PHYTO). Plants grown without soil amendment did not reduce total Cu and free Cu ions in leachates. Lemna minor L. was used to assess the leachate phytotoxicity, and based on its growth, the DL, LDS, OM and OMDL leachates were less phytotoxic than the OMZ, PHYTO and UNT ones. The LDS leachates had the lowest Cu, Cu(2+), Fe, and Zn concentrations, but L. minor developed less in these leachates than in a mineral water and a river freshwater. Leachate Mg concentrations were in decreasing order OMDL>DL>PHYTO=OM=LDS>UNT=OMZ and influenced the duckweed growth. PMID:22000292

Marchand, Lilian; Mench, Michel; Marchand, Charlotte; Le Coustumer, Philippe; Kolbas, Aliaksandr; Maalouf, Jean-Paul

2011-12-01

126

Egg parasitoids of Edessa meditabunda (Fabricius) (Pentatomidae) in lettuce crop  

Scientific Electronic Library Online (English)

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

Bruna M., Favetti; Diones, Krinski; Alessandra R., Butnariu; Marta S., Loiácono.

127

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

Directory of Open Access Journals (Sweden)

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

Bruna M. Favetti

2013-06-01

128

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

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

Catello Pane

2014-08-01

129

The effect of competition from neighbours on stomatal conductance in lettuce and tomato plants.  

Science.gov (United States)

Competition decreased transpiration from young lettuce plants after 2 days, before any reductions in leaf area became apparent, and stomatal conductance (g(s) ) of lettuce and tomato plants was also reduced. Stomatal closure was not due to hydraulic signals or competition for nutrients, as soil water content, leaf water status and leaf nitrate concentrations were unaffected by neighbours. Competition-induced stomatal closure was absent in an abscisic acid (ABA)-deficient tomato mutant, flacca, indicating a fundamental involvement of ABA. Although tomato xylem sap ABA concentrations were unaffected by the presence of neighbours, ABA/pH-based stomatal modulation is still likely to underlie the response to competition, as soil and xylem sap alkalization was observed in competing plants. Competition also modulated leaf ethylene production, and treatment of lettuce plants with an ethylene perception inhibitor (1-methylcyclopropene) diminished the difference in g(s) between single and competing plants grown in a controlled environment room, but increased it in plants grown in the greenhouse: ethylene altered the extent of the stomatal response to competition. Effects of competition on g(s) are discussed in terms of the detection of the absence of neighbours: increases in g(s) and carbon fixation may allow faster initial space occupancy within an emerging community/crop. PMID:21241329

Vysotskaya, Lidiya; Wilkinson, Sally; Davies, William J; Arkhipova, Tatyana; Kudoyarova, Guzel

2011-05-01

130

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

Science.gov (United States)

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

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

2012-01-01

131

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

Science.gov (United States)

NASA's 2010 Desert Research and Technology Studies (DRATS) of the VEGGIE Food Production System in the Habitat Demonstration Unit (HDU) Pressurized Excursion Module (PEM) was the first operational evaluation of salad crop production technology in a NASA analog test. Rooting media and slow release fertilizers were evaluated for three lettuce cultivars that had shown promise as candidates for a surface based food production system. These tests involved comparing growth, color and quality of the lettuce cultivars grown under VEGGIE LED array (Orbitec, Madison, WI) or Biomass Production System for Education ((BSEe), Orbitec, Madison, WI) compact fluorescent lamps using a gravity feed water delivery system. Mission relevant conditions of CO2, temperature and RH were maintained using controlled environment chambers (EGC, Chagrin Falls, OH). Growth data was obtained for the two red leaf lettuce cultivars, Outredgeous and Firecracker, and the green Bibb lettuce cultivar, Flandria. Growth and quality was evaluated using different concentrations (7.5 g/L and 15 g/L) of commercial slow release fertilizer (Osmocote Plus 15-9-12, Scotts, Maryville, OH) and Nutricote 18-6-8 (Florikan, Sarasota, FL) in either a peat/vermiculite media (sunshine LP5 MiX, Sungro, Bellview, WA) or calcined montmorillonite clay [(arcillite,)Turface Proleague, Profile LLC, Buffalo Grove, IL]. The commercial peat/vermiculite mix generally resulted in larger plants than those grown in arcillite. Increasing the concentration of Osmocote from 7.5 to 15 g/L increased the height, dry mass, and leaf area of lettuce cultivars. In contrast, there was a decrease in growth parameters when concentration of Nutricote was increased from 7.5 to 15 g/L. The best growth was obtained with the 7.5 g/L Nutricote using a commercial peat/vermiculite mixture. This media was used for field testing VEGGIE plant system in the 2010 DRAT test. The VEGGIE nutrient delivery system worked well, was able to be maintained by multiple operators with a minimum of training, and supported excellent lettuce growth for the duration of the 14-day test. The operational DRAT field testing in the HDU identified light quality issues related to morphology and pigment development that will need to be addressed through additional testing. Feedback from the crew, ground support personnel, and human factors leads was uniformly positive on the psychological value of having the crop production system in the pressurized excursion module. Data are being used to design a plant atrium with LED lighting to evaluate salad crop growth during NASA's 2011 DRATS test.

Stutte, Gary W.; Newsham, Gerard; Wheeler, Raymond

2011-01-01

132

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

International Nuclear Information System (INIS)

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

133

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

Science.gov (United States)

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 virulence factors and therapeutic strategies to combat them. PMID:24223216

Thomson, Euan L S; Dennis, Jonathan J

2013-01-01

134

Inactivation of Escherichia coli O157:H7, Salmonella enterica serotype enteritidis, and Listeria monocytogenes on lettuce by hydrogen peroxide and lactic acid and by hydrogen peroxide with mild heat.  

Science.gov (United States)

Iceberg lettuce is a major component in vegetable salad and has been associated with many outbreaks of foodborne illnesses. In this study, several combinations of lactic acid and hydrogen peroxide were tested to obtain effective antibacterial activity without adverse effects on sensory characteristics. A five-strain mixture of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis, and Listeria monocytogenes was inoculated separately onto fresh-cut lettuce leaves, which were later treated with 1.5% lactic acid plus 1.5% hydrogen peroxide (H2O2) at 40 degrees C for 15 min, 1.5% lactic acid plus 2% H2O2 at 22 degrees C for 5 min, and 2% H2O2 at 50 degrees C for 60 or 90 s. Control lettuce leaves were treated with deionized water under the same conditions. A 4-log reduction was obtained for lettuce treated with the combinations of lactic acid and H2O2 for E. coli O157:H7 and Salmonella Enteritidis, and a 3-log reduction was obtained for L. monocytogenes. However, the sensory characteristics of lettuce were compromised by these treatments. The treatment of lettuce leaves with 2% H2O2 at 50 degrees C was effective not only in reducing pathogenic bacteria but also in maintaining good sensory quality for up to 15 days. A 0.05) between pathogen population reductions obtained with 2% H2O2 with 60- and 90-s exposure times. Hydrogen peroxide residue was undetectable (the minimum level of sensitivity was 2 ppm) on lettuce surfaces after the treated lettuce was rinsed with cold water and centrifuged with a salad spinner. Hence, the treatment of lettuce with 2% H2O2 at 50 degrees C for 60 s is effective in initially reducing substantial populations of foodborne pathogens and maintaining high product quality. PMID:12182470

Lin, Chia-Mi; Moon, Sarah S; Doyle, Michael P; McWatters, Kay H

2002-08-01

135

Nutritional Efficiency of Phosphorus in Lettuce  

Directory of Open Access Journals (Sweden)

Full Text Available This work aimed to evaluate the efficiency of phosphorus absorption, translocation, and utilization in lettuce. A greenhouse experiment was arranged in a completely randomized design in a 5x2 factorial scheme to test five phosphorus doses (0, 100, 200, 300, and 500 mg dm-3 and two lettuce varieties (Lisa and Americana. The soil was incubated with limestone for pH correction. Following this procedure, a phosphate fertilization was carried and the lettuce seedlings were transplanted. Fertilization with nitrogen and potassium were applied as cover. Forty days after seedling transplantation, the plants were separated into root and aerial part to determine the following characteristics: aerial part dry matter (APDM; root dry matter (RDM; phosphorus content in the aerial part (PCAP; phosphorus content in the root (PCR; phosphorus accumulation in the aerial part (PAAP; phosphorus accumulation in the roots (PAR; phosphorus absorption efficiency (PAE; phosphorus translocation efficiency (PTE; phosphorus use efficiency in the aerial part (PUEAP and root-aerial part ratio (R/AP. The results obtained allowed to conclude that RDM and R/AP had a significant interaction between the varieties and the P doses, with Lisa presenting the highest values of these characteristics at the lowest doses evaluated. The characteristics PCAP, PAAP and PAE presented a significant difference between the varieties, with the Americana presenting the highest values. The characteristics PCAP, PAAP, EAP, APDM and PUEAP presented a significant difference between the P doses, with the highest values found at the dose of 500 mg dm-3, except for PUEAP, whose dose was 0 mg dm-3.

Ana Paula Almeida Bertossi

2013-07-01

136

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

Science.gov (United States)

Widespread use of radiofrequency radiation emitting devices increased the exposure to electromagnetic fields (EMFs) from 300 MHz to 300 GHz. Various biological effects of exposure to these fields have been documented so far, but very little work has been carried out on plants. The aim of the present work was to investigate the physiological responses of the plant Lemna minor after exposure to radiofrequency EMFs, and in particular, to clarify the possible role of oxidative stress in the observed effects. Duckweed was exposed for 2 h to EMFs of 400 and 900 MHz at field strengths of 10, 23, 41 and 120 V m(-1). The effect of a longer exposure time (4 h) and modulation was also investigated. After exposure, parameters of oxidative stress, such as lipid peroxidation, H(2)O(2) content, activities and isoenzyme pattern of antioxidative enzymes as well as HSP70 expression were evaluated. At 400 MHz, lipid peroxidation and H(2)O(2) content were significantly enhanced in duckweed exposed to EMFs of 23 and 120 V m(-1) while other exposure treatments did not have an effect. Compared to the controls, the activities of antioxidative enzymes showed different behaviour: catalase (CAT) activity increased after most exposure treatments while pyrogallol (PPX) and ascorbate peroxidase (APX) activities were not changed. Exceptions were reduced PPX and APX activity after longer exposure at 23 V m(-1) and increased PPX activity after exposures at 10 and 120 V m(-1). By contrast, at 900 MHz almost all exposure treatments significantly increased level of lipid peroxidation and H(2)O(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(-1) which increased PPX and CAT activity. At this frequency APX activity was significantly decreased after exposure at 10 V m(-1) and longer exposure at 23 V m(-1) but it increased after a shorter exposure at 23 V m(-1). At both frequencies no differences in isoenzyme patterns of antioxidative enzymes or HSP70 level were found between control and exposed plants. Our results showed that non-thermal exposure to investigated radiofrequency fields induced oxidative stress in duckweed as well as unspecific stress responses, especially of antioxidative enzymes. However, the observed effects markedly depended on the field frequencies applied as well as on other exposure parameters (strength, modulation and exposure time). Enhanced lipid peroxidation and H(2)O(2) content accompanied by diminished antioxidative enzymes activity caused by exposure to investigated EMFs, especially at 900 MHz, indicate that oxidative stress could partly be due to changed activities of antioxidative enzymes. PMID:17825879

Tkalec, Mirta; Malari?, Kresimir; Pevalek-Kozlina, Branka

2007-12-15

137

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

International Nuclear Information System (INIS)

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

138

Quantitative proteomic analysis of the Salmonella-lettuce interaction.  

Science.gov (United States)

Human pathogens can internalize food crops through root and surface uptake and persist inside crop plants. The goal of the study was to elucidate the global modulation of bacteria and plant protein expression after Salmonella internalizes lettuce. A quantitative proteomic approach was used to analyse the protein expression of Salmonella enterica serovar Infantis and lettuce cultivar Green Salad Bowl 24?h after infiltrating S. Infantis into lettuce leaves. Among the 50 differentially expressed proteins identified by comparing internalized S. Infantis against S. Infantis grown in Luria Broth, proteins involved in glycolysis were down-regulated, while one protein involved in ascorbate uptake was up-regulated. Stress response proteins, especially antioxidant proteins, were up-regulated. The modulation in protein expression suggested that internalized S. Infantis might utilize ascorbate as a carbon source and require multiple stress response proteins to cope with stresses encountered in plants. On the other hand, among the 20 differentially expressed lettuce proteins, proteins involved in defense response to bacteria were up-regulated. Moreover, the secreted effector PipB2 of S. Infantis and R proteins of lettuce were induced after bacterial internalization into lettuce leaves, indicating human pathogen S. Infantis triggered the defense mechanisms of lettuce, which normally responds to plant pathogens. PMID:24512637

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

2014-11-01

139

THE OCCURRENCE OF APIOSE IN LEMNA (DUCKWEED) AND OTHER ANGIOSPERMS.  

Science.gov (United States)

1. The branched-chain pentose apiose reacts with the benzidine-trichloroacetic acid reagent on paper chromatograms to give a yellow spot with.an intense white fluorescence in ultraviolet light; on chromatograms developed with butanol-acetic acid-water this spot lies between fucose and rhamnose. 2. Examination of paper chromatograms of hydrolysates of whole plant material has shown the presence of a substance with these properties in a wide variety of species. 3. Among the plants examined two members of the Lemnaceae (Lemna minor and Wolffia arrhiza) were found to be especially rich sources, comparable with Posidonia australis (Bell, Hardwick, Isherwood & Cahn, 1954). 4. Measurements of the apiose content of fractions derived from Lemna have shown that the sugar is present at a concentration of about 4% in the holocellulose, and part of this is retained in the alpha-cellulose left by extraction with 24% (w/v) potassium hydroxide containing borate. PMID:14340070

DUFF, R B

1965-03-01

140

Ethylene evolution and endo-b-mannanase activity during lettuce seed germination at high temperature  

Directory of Open Access Journals (Sweden)

Full Text Available 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 aminoethoxyvinylglycine (AVG, or 20 mmol L-1 of silver thiosulphate (STS. Seeds were also primed in polyethylene glycol (PEG, or PEG + ACC, PEG + AVG, or PEG + STS. Untreated seeds germinated 100% at 20°C. At 35°C, EVE seeds germinated 100%, whereas DGB seeds germinated only 33%. Seed priming or adding ACC during incubation increased germination at 35°C. Higher ethylene evolution was detected in EVE than in DGB during germination at 35°C. AVG did not inhibit seed germination of DGB at 35°C, but STS did. Higher endo-beta-mannanase activity was observed in EVE compared with DGB seeds. Providing ACC either during priming or during germination increased endo-beta-mannanase activity, whereas AVG and STS led to decreased or no activity. Ethylene may overcome the inhibitory effect of high temperature in thermosensitive lettuce seeds due to increased endo-beta-mannanase, possibly leading to weakening of the endosperm.

Nascimento Warley Marcos

2004-01-01

 
 
 
 
141

Tobacco streak virus isolated from lettuce.  

Science.gov (United States)

Tobacco streak virus (TSV) is an ilarvirus with a worldwide distribution. This virus infects many plants and causes significant yield losses. In this study, 300 samples of lettuce were collected from lettuce fields in Tehran Province. Infected plants show symptoms such as: mosaic, vein clearing, vein necrosis, yellowing and leaf distortion. DAS-ELISA (Double Antibody Sandwich-ELISA) was used with a polyclonal antiserum against TSV. Five isolates (T1, T2, T3, T4 and T5), which are collected, respectively from Mohammad Abad (Karaj), Malek Abad (Karaj), Hashtgerd (Karaj), Tarand Balla (Varamin) and Deh mah sin (Pishva) were inoculated on 29 species of Cucurbitaceae, Amaranthaceae, Solanacea, Compositae, Leguminosae and Chenopodiacea. Chenopodium quinoa 6 days after inoculation showed necrotic local lesions. Gomphrena globosa 10 days after inoculation developed chlorotic local lesions. Systemic symptoms were produced in Datura stramonium. Phaseolus vulgaris cv. Red Kidney 5 days after inoculation developed necrotic local lesions. Nicotiana tabacum 7 days after inoculation showed necrotic and chlorotic local lesions. Nicotiana clevelandii 15 days after inoculation developed leaf distortion and vein necrosis. Lactuca sativa 10-15 days after inoculation developed leaf istortion and mosaic. Reverse Transcription Polymerase Chain Reaction (RT-PCR) was performed using one primer pairs designed by DSMZ. An approximately 710 bp fragment was amplified with a specific primer. PMID:19634475

Abtahi, F S; Khodai Motlagh, M

2009-05-01

142

Tobacco streak virus Isolated from Lettuce  

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

F.S. Abtahi

2009-01-01

143

Allelopathic action essential oils of alecrim-pimenta and lemongrass in germination of lettuce achenes
Ação alelopática de óleos essenciais de alecrim-pimenta e capimsanto na germinação de aquênios de alface
 

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The alecrim-pimenta and the lemongrass produce secondary compounds that can be used in alternative management of weed. The objective of this work was to evaluate the allelopathic effect of the essential oils of alecrim-pimenta and lemongrass in germination of lettuce achenes. It was used mature leaves of both species, and extracted the essential oil by distillation method of drag by water vapor. The bioassay was performed using achenes of crisp-leaf lettuce for summer and arranged in factoria...

Hélida Mara Magalhães; César Fernandes Aquino; Eriksen Patric Silva Soares; Leonardo David Tuffi Santos; Paulo Sergio Nascimento Lopes

2013-01-01

144

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  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 aminoethoxyviny...

Warley Marcos Nascimento; Daniel James Cantliffe; Donald John Huber

2004-01-01

145

Phytoaccumulation and phytotoxicity of cadmium and chromium in duckweed Wolffia globosa.  

Science.gov (United States)

The phytoaccumulation and phytotoxicity of heavy metals, cadmium (Cd), and chromium (Cr) on a common duckweed, Wolffia globosa, were studied. W. globosa were cultured in 3% Hoagland's nutrient medium, which was supplemented with 1, 2, 4, and 8 mg/L of Cd and Cr and were separately harvested after 3, 6, 9, and 12 days. The accumulation of Cd and Cr in W. globosa showed significant increases when the exposure time and metal concentration were increased. The effects of Cd and Cr on the biomass productivity and total chlorophyll content in W. globosa indicated that there were significant decreases in the biomass productivity and total chlorophyll content when the exposure time and metal concentration were increased. PMID:12655803

Boonyapookana, Benjaporn; Upatham, E Suchart; Kruatrachue, Maleeya; Pokethitiyook, Prayad; Singhakaew, Sombat

2002-01-01

146

Desempenho da alface em cultivo orgânico com e sem cobertura morta e diferentes lâminas d'água Lettuce crop performance in organic tillage with and without mulching and at different irrigation water depths  

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Full Text Available O experimento foi conduzido no período de 27/05/2006 a 02/08/2006 no SIPA (Sistema Integrado de Produção Agroecológica, localizado no município de Seropédica-RJ. Nesse trabalho, objetivou-se avaliar o desempenho da cultura da alface (Lactuca sativa L. cultivada sob diferentes lâminas de irrigação em um solo sem e com cobertura de palhada da leguminosa gliricídia. Foram conduzidos dois experimentos simultâneos, utilizando o delineamento experimental de blocos ao acaso, em ambos os experimentos, nos quais foram aplicadas 5 lâminas de irrigação, correspondendo a 25, 50, 80, 100, 115 % da evapotranspiração da cultura (ETc, sendo a produção final avaliada por meio da determinação da massa fresca, área foliar e número de folhas. Até o nível de 100% ETc, todas as variáveis analisadas tiveram seus valores aumentados, e para o nível de 115%, houve um decrescimento das mesmas. Na produção de massa fresca total, o sistema de cultivo com utilização de cobertura morta foi superior ao sem cobertura não diferenciando estatisticamente ao nível de 5 % probabilidade pelo teste F somente nas lâminas de 25 e 115% ETc.This work was carried out in order to evaluate the performance of a lettuce crop (Lactuca sativa L. cultivated under different irrigation depths in ground with and without covering of gliricidia leguminosa. Two simultaneous experiments were conducted, in which 5 irrigation depths were applied, corresponding to 25, 50, 80, 100, and 115% of crop evapotranspiration (ETc. Final production was evaluated by means of the determination of fresh mass and leaf area. Up to the 100% ETc level, all the analyzed variables had their values increased. For the 115% level, there was a decrease of the same. In total fresh mass production, the system with covering was superior to the one without covering, not differentiating statistically to the 5% level probability for test F, except at depths of 25 and 115% ETc.

Márcio Emanoel de Lima

2009-12-01

147

Desempenho da alface em cultivo orgânico com e sem cobertura morta e diferentes lâminas d'água / Lettuce crop performance in organic tillage with and without mulching and at different irrigation water depths  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O experimento foi conduzido no período de 27/05/2006 a 02/08/2006 no SIPA (Sistema Integrado de Produção Agroecológica), localizado no município de Seropédica-RJ. Nesse trabalho, objetivou-se avaliar o desempenho da cultura da alface (Lactuca sativa L.) cultivada sob diferentes lâminas de irrigação [...] em um solo sem e com cobertura de palhada da leguminosa gliricídia. Foram conduzidos dois experimentos simultâneos, utilizando o delineamento experimental de blocos ao acaso, em ambos os experimentos, nos quais foram aplicadas 5 lâminas de irrigação, correspondendo a 25, 50, 80, 100, 115 % da evapotranspiração da cultura (ETc), sendo a produção final avaliada por meio da determinação da massa fresca, área foliar e número de folhas. Até o nível de 100% ETc, todas as variáveis analisadas tiveram seus valores aumentados, e para o nível de 115%, houve um decrescimento das mesmas. Na produção de massa fresca total, o sistema de cultivo com utilização de cobertura morta foi superior ao sem cobertura não diferenciando estatisticamente ao nível de 5 % probabilidade pelo teste F somente nas lâminas de 25 e 115% ETc. Abstract in english This work was carried out in order to evaluate the performance of a lettuce crop (Lactuca sativa L.) cultivated under different irrigation depths in ground with and without covering of gliricidia leguminosa. Two simultaneous experiments were conducted, in which 5 irrigation depths were applied, corr [...] esponding to 25, 50, 80, 100, and 115% of crop evapotranspiration (ETc). Final production was evaluated by means of the determination of fresh mass and leaf area. Up to the 100% ETc level, all the analyzed variables had their values increased. For the 115% level, there was a decrease of the same. In total fresh mass production, the system with covering was superior to the one without covering, not differentiating statistically to the 5% level probability for test F, except at depths of 25 and 115% ETc.

Márcio Emanoel de, Lima; Daniel Fonseca de, Carvalho; Adilson Pacheco de, Souza; José Guilherme Marinho, Guerra; Raul de Lucena Duarte, Ribeiro.

148

Potential sources affecting the activity concentrations of 238U, 235U, 232Th and some decay products in lettuce and wheat samples.  

Science.gov (United States)

The activity concentrations of radionuclides within the uranium and thorium series were determined in wheat and lettuce at five sites in France, and in their respective potential sources: crop soils of wheat and crop soils and irrigation waters of lettuce. These data were used to calculate concentration ratios and to enrich the database supported by the technical report series N°472 of the IAEA (2010). For wheat and lettuce, the activity concentrations were in the same range for all radionuclides studied, except for (210)Pb, which had higher activity concentrations in wheat, ranging between 1.3 and 11 Bq kg(?1) (fresh weight) as compared to 0.4 and 0.7 Bq kg(?1) (fresh weight) for lettuce. For wheat, the range of activity concentrations (mBq kg(?1); fresh weight) decreased as (210)Pb > (226)Ra (56–1511) ? (228)Ra (86–769) > (228)Th (19–176) ? (238)U (11–169) ? (234)U (12–150) ? (230)Th (9.08–197.18) ? (232)Th (8.61–121.45) > (235)U (0.53–7.9). For lettuce, it decreased as (228)Ra ( (210)Pb (409–746) > (226)Ra (30–599) ? (228)Th ( (238)U (8–120) ? (234)U (8–121) ? (230)Th (5.21–134.63) ? (232)Th (5.25–156.99) > (235)U (0.35–5.63). The species differences may reflect different plant physiologies. Through the study of activity ratios of wheat and lettuce in relation with those of the various radionuclide sources it has been possible to highlight the contribution of the main sources of natural radionuclides. Indeed, irrigation water when the uranium concentration is enhanced (>30 mBq L(?1)) contributed significantly to the activity concentration of uranium in lettuces. Concerning the high activity concentrations of (210)Pb, it could be explained by atmospheric particle deposition. The effect of soil particles resuspension and their adhesion to the plant surface seemed to be important in some cases. The soil-to-plant transfer factors were calculated for lettuce and wheat. The values were lower in wheat than in lettuce except for (210)Pb which had similar values in the two species (0.11–0.13 respectively). For both species, (210)Pb followed by (228)Ra (0.015–0.10) and (226)Ra (0.010–0.051) displayed the highest transfer factor, whereas (238)U had intermediate values (0.0015–0.030) and (232)Th exhibited the lowest (0.0014–0.013). PMID:23001397

Jeambrun, M; Pourcelot, L; Mercat, C; Boulet, B; Pelt, E; Chabaux, F; Cagnat, X; Gauthier-Lafaye, F

2012-11-01

149

Lettuce achene invigoration through osmopriming at supraoptimal temperature  

International Nuclear Information System (INIS)

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

150

Preliminary investigations of the rhizosphere nature of hydroponically grown lettuces  

Science.gov (United States)

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

Antunes, Inês; Paille, Christel; Lasseur, Christophe

151

Nitrogenase Activity of Pseudomonas corrugata Isolated from Egyptian Lettuce  

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Full Text Available In the present study an isolate capable of root colonization of Egyptian Lettuce was isolated from the roots after selective enrichment. The isolated strain was identified as Pseudomonas corrugata by using Biochemical and Biolog identification system. The isolate has been found to be positive for nitrogenase activity. This root-colonized bacterium has not been previously isolated from Egyptian Lettuce and could be used as a bio-fertilizer.

Emad A. Abada

2006-01-01

152

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

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

Olorunfemi, Temitope O.S.

2006-01-01

153

Prediction Model of Lettuce Nitrogen Content Based on Color Images  

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Full Text Available In order to facilitate intelligent precise nitrogen fertilizer management, a model of lettuce leaves’ nitrogen content is constructed. In this article, the lettuce samples of several nitrogen levels were cultivated. At Rosette stage, color images of lettuce leaves with every nitrogen level were collected and preprocessed and the texture features and the color features were extracted. Through the correlation analysis, principal component characteristics were extracted and image feature vectors were constructed after being screened and optimized. The regression equations of image feature vector and lettuce leaf nitrogen content were constructed by the principal component regression analysis method and the multiple linear regression method respectively. Based on the same test samples, prediction error rates of two expression models were computed. Results showed that the average error ratio of the principal component regression expression model is 9.30% and the one of multiple linear regression expression is 12.66%. The root mean square errors (RMSEP of PCR model was 0.4577 and the RMSEP of MLR model was 0.6284. It is also shown that the prediction result of the principal component regression expression model is better than the one of the latter and it can be applied to the nondestructive testing intuitive expression model of the nitrogen content of lettuce leaf. This study provides a basis or way to fertilize and manage nitrogen fertilizer precisely for lettuce or other crops.

Zhang Bing

2013-01-01

154

Quantitative microbial risk assessment for Escherichia coli O157 on lettuce, based on survival data from controlled studies in a climate chamber.  

Science.gov (United States)

The aims of the study were to determine the survival of Escherichia coli O157 on lettuce as a function of temperature and light intensity, and to use that information in a screening-level quantitative microbial risk assessment (QMRA) in order to evaluate risk-reducing strategies including irrigation water quality guidelines, rinsing, and holding time between last irrigation and harvest. Iceberg lettuce was grown in a climate chamber and inoculated with E. coli O157. Bacterial numbers were determined with the standard plate count method after inoculation and 1, 2, 4, and 7 day(s) postinoculation. The experiments were carried out at 11, 18, and 25°C in light intensities of 0, 400, and 600 mmol (m(2))(-1) s(-1). There was a significant effect of temperature and light intensity on survival, with less bacteria isolated from lettuce incubated at 25 and 18°C compared with 11°C (P QMRA compared the relative risk with lettuce consumption from 20 scenarios. A stricter water quality guideline gave a mean fivefold risk reduction. Holding times of 1, 2, 4, and 7 day(s) reduced the risk 3, 8, 8, and 18 times, respectively, compared with harvest the same day as the last irrigation. Finally, rinsing lettuce for 15 s in cold tap water prior to consumption gave a sixfold risk reduction compared with eating unrinsed lettuce. Sensitivity analyses indicated that variation in bacterial inactivation had the most significant effect on the risk outcome. A QMRA determining the relative risks between scenarios reduces uncertainty and can provide risk managers with decision support. PMID:22186038

Ottoson, Jakob R; Nyberg, Karin; Lindqvist, Roland; Albihn, Ann

2011-12-01

155

Effects of genotype and transpiration rate on the uptake and accumulation of perchlorate (ClO4-) in lettuce.  

Science.gov (United States)

Although evidence of perchlorate accumulation in plants exists, there is a scarcity of information concerning the key factors and mechanisms involved. To ascertain whether genotypic variation in perchlorate accumulation occurs within lettuce, hydroponic plant uptake experiments were conducted with five types of lettuce (Lactuca sativa L.), which were grown to market size atthree perchlorate (ClO4-) concentrations (1, 5, or 10 microg/L). Perchlorate accumulated in the leafy tissues to varying amounts, ranging from 4 to 192 microg/kg fresh weight (FW), and the ranking of perchlorate accumulation was crisphead > butter head > romaine > red leaf > green leaf. The effect of transpiration rate on perchlorate accumulation was further examined using crisphead, butter head, and green leaf lettuce. By growing lettuce in controlled-environment chambers with two climatic regimes, "cloudy, humid, cool" (80% RH, 18/15 degrees C, 250 micromol/m2s photosynthetic photon flux density (PPFD)) and "sunny, dry, warm" (approximately 50% RH, 28/18 degrees C, 500 micromol/m2s PPFD), up to 2.7-fold differences in transpiration rates were achieved. Across all three genotypes, the plants that transpired more water accumulated more perchlorate on a whole-head basis; however, the effect of transpiration rate on perchlorate accumulation was not as great as expected. Despite 2.0-2.7-fold differences in transpiration rate, there were only 1.2-2.0-fold differences in perchlorate accumulation. In addition to whole-head analysis, plants were sectioned into inner, middle, and outer leaves and processed separately. Overall, the ranking of perchlorate accumulation was outer leaves > middle leaves > inner leaves. Transpiration rate has a clear effect on perchlorate accumulation in lettuce, but other factors are influential and deserve exploration. PMID:17539550

Seyfferth, Angelia L; Parker, David R

2007-05-01

156

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

Science.gov (United States)

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

Ahmadi, L.; Dupont, R.

2013-12-01

157

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

Energy Technology Data Exchange (ETDEWEB)

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

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

158

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

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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.

Reza Mohajer

2014-07-01

159

Application of response surface methodology for obtaining lettuce (Lactuca sativa L.) by-products extracts with high antioxidative properties  

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The main objective of the present work was to optimize the extraction conditions for simultaneous maximization of total reducing (TRC) and antioxidant (AC) capacities for lettuce (Lactuca sativa L.) by-products extracts, using response surface methodology. For this, a design of experiments (DOE) with different combinations of solvents (water, methanol and acetone) extraction temperatures (30–60 ?C) and time (10–60 min) on the TRC and AC was applied. Higher and consistent ?tti...

Gomes, Teresa; Delgado, Teresa; Ferreira, Anabela; Pereira, J. A.; Baptista, Paula; Casal, Susana; Ramalhosa, Elsa

2013-01-01

160

Characteristics of a Lettuce mosaic virus Isolate Infecting Lettuce in Korea  

Science.gov (United States)

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.

Lim, Seungmo; Zhao, Fumei; Yoo, Ran Hee; Igori, Davaajargal; Lee, Su-Heon; Lim, Hyoun-Sub; Moon, Jae Sun

2014-01-01

 
 
 
 
161

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

Science.gov (United States)

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. PMID:25289001

Lim, Seungmo; Zhao, Fumei; Yoo, Ran Hee; Igori, Davaajargal; Lee, Su-Heon; Lim, Hyoun-Sub; Moon, Jae Sun

2014-06-01

162

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

International Nuclear Information System (INIS)

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

163

Allelopathic effects of the toxic cyanobacterium Microcystis aeruginosa on duckweed, Lemna gibba L.  

Science.gov (United States)

Cyanotoxins are a group of compounds produced by cyanobacteria that can have severe physiological effects on other organisms, including humans. The potential allelopathic effects of Microcystis aeruginosa, a toxic cyanobacterium, on the duckweed plant, Lemna gibba L., were examined using three experimental methods: (1) a series of toxicity bioassays, (2) evaluation of toxin production by M. aeruginosa in the direct and indirect presence of L. gibba, and (3) inhibition of oxygen evolution in photosynthesis. The results showed that, first, there were no clear dose-dependent effects of the microcystin-LR standard or the toxic M. aeruginosa culture filtrate on any of the end points measured in the toxicity bioassays (plant and frond number, dry weight, growth rate, chlorophyll content; one-way ANOVA, p > 0.05). In those cases in which an EC(50) value could be obtained, chlorophyll a was the most sensitive end point, as it had the lowest EC(50) value (14.47 microg/L microcystin-LR) of all the end points. Second, the presence of L. gibba did not result in higher microcystin-LR production in the toxic M. aeruginosa culture. And, last, oxygen evolution was not affected in isolated chloroplasts exposed directly to microcystin-LR. Therefore, microcystins from the toxic cyanobacterium Microcystis aeruginosa do not appear to have an allelopathic effect on the common aquatic macrophyte Lemna gibba. PMID:15712290

LeBlanc, Susan; Pick, Frances R; Aranda-Rodriguez, Rocio

2005-02-01

164

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.  

Directory of Open Access Journals (Sweden)

Full Text Available A utilização do efluente de esgoto tratado para poupar os corpos d'água utilizados para irrigação tem sido de grande interesse na agricultura, e o uso não regulamentado desta prática pode acarretar mudanças no comportamento físico-químico do solo. Sua prática tem sido de grande interesse em vista da redução da quantidade de água retirada dos mananciais, preservando-os. Objetivou-se, neste trabalho, a avaliação dos atributos físico-químicos de um Latossolo Vermelho-Amarelo após aplicação de água de reúso. O experimento foi realizado em uma condição de casa de vegetação onde foram cultivados dois ciclos da alface-crespa (Lactuca sativa, L com dois tratamentos, com três repetições cada: testemunhas (água de abastecimento proveniente de poço e reúso (proveniente de esgoto local. Os resultados mostraram que não ocorreram aumentos em alguns atributos químicos de fertilidade, como ferro, magnésio, zinco, boro, potássio, nitrato, sódio e cálcio; decréscimo nos valores de matéria orgânica e manganês, além de diminuição da condutividade hidráulica e aumento na condutividade elétrica do solo. Observou-se, ainda, redução do pH no solo, além do aumento da RAS e PST. Desta forma, concluiu-se que a utilização de água de reúso para fins agronômicos deve ser de forma racional, monitorando-se, principalmente, a elevação do teor de sais no solo.The use of treated sewage effluent to save the ponds used for irrigation has been of great interest in agriculture, and the unregulated use of this practice can cause changes in physical and chemical behavior of the soil. This practice has been of great interest in view of reducing the quantity of water withdrawal from the springs and its preservation. The objective of this study is to evaluate the physical and chemical attributes of a Red-yellow Dystrophic Latosol after the implementation of water reuse. The experiment was conducted in a condition of greenhouse 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.

Antonio C. T. Varallo

2012-04-01

165

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

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

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

2013-02-01

166

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.)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A utilização do efluente de esgoto tratado para poupar os corpos d'água utilizados para irrigação tem sido de grande interesse na agricultura, e o uso não regulamentado desta prática pode acarretar mudanças no comportamento físico-químico do solo. Sua prática tem sido de grande interesse em vista da [...] redução da quantidade de água retirada dos mananciais, preservando-os. Objetivou-se, neste trabalho, a avaliação dos atributos físico-químicos de um Latossolo Vermelho-Amarelo após aplicação de água de reúso. O experimento foi realizado em uma condição de casa de vegetação onde foram cultivados dois ciclos da alface-crespa (Lactuca sativa, L) com dois tratamentos, com três repetições cada: testemunhas (água de abastecimento proveniente de poço) e reúso (proveniente de esgoto local). Os resultados mostraram que não ocorreram aumentos em alguns atributos químicos de fertilidade, como ferro, magnésio, zinco, boro, potássio, nitrato, sódio e cálcio; decréscimo nos valores de matéria orgânica e manganês, além de diminuição da condutividade hidráulica e aumento na condutividade elétrica do solo. Observou-se, ainda, redução do pH no solo, além do aumento da RAS e PST. Desta forma, concluiu-se que a utilização de água de reúso para fins agronômicos deve ser de forma racional, monitorando-se, principalmente, a elevação do teor de sais no solo. Abstract in english The use of treated sewage effluent to save the ponds used for irrigation has been of great interest in agriculture, and the unregulated use of this practice can cause changes in physical and chemical behavior of the soil. This practice has been of great interest in view of reducing the quantity of w [...] ater withdrawal from the springs and its preservation. The objective of this study is to evaluate the physical and chemical attributes of a Red-yellow Dystrophic Latosol after the implementation of water reuse. The experiment was conducted in a condition of greenhouse 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.

Antonio C. T., Varallo; Claudinei F., Souza; Bruno de L., Santoro.

2012-04-01

167

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

Science.gov (United States)

Monocultures of functional equivalent species often negatively affect nutrient cycling and overall biodiversity of aquatic ecosystems. The importance of water and sediment nutrients for the occurrence of monocultures was analysed using field data from drainage ditches. Ranges of nutrients were identified that best explained the occurrence of monocultures of Elodea nuttallii (Planch.) St. John (Waterweed type), monocultures of duckweed (Duckweed type) and the occurrence of a diverse submerged vegetation (Mixed type). Results indicated these three vegetation types occurred at distinctive ranges of phosphorus in water and sediment. Sediment phosphorus distinguished monocultures from the Mixed type, with the two monocultures occurring at two to four times higher concentrations. The Waterweed type occurred at higher sediment phosphorus levels than the mixed type, showed a higher degree of dominance and lower number of red list species. Phosphorus concentrations in water were four to six times higher in the Duckweed type compared to the Waterweed and Mixed type. The three vegetation types had comparable total biomass which was unexpected. This comparability was likely caused by duckweed only growing at the water surface at the highest nutrient levels and the limited space in drainage ditches for increased submerged biomass development at high nutrient availability. Possible measures to limit the occurrence of monocultures, and thereby increasing the ecological quality, are discussed with focus on lowering phosphorus concentrations in both water and sediment and on removal of plant species that develop into monocultures. PMID:24255858

van Zuidam, Jeroen P; Peeters, Edwin Thm

2013-01-01

168

Lettucenin sesquiterpenes contribute significantly to the browning of lettuce.  

Science.gov (United States)

Wound-induced changes in the composition of secondary plant compounds cause the browning of processed lettuce. Cut tissues near the lettuce butt end clearly exhibit increased formation of yellow-brown pigments. This browning reaction is typically been attributed to the oxidation of polyphenols by the enzyme polyphenol oxidase (PPO). However, in our previous study on Iceberg lettuce, we showed that, besides the enzymatic polyphenol browning, other reactions must be involved in the formation of colored structures. With the present study for the first time, we isolated yellow sesquiterpenes by multilayer countercurrent chromatography (MLCCC), followed by preparative high-performance liquid chromatography (HPLC). Further analyses by nuclear magnetic resonance (NMR) and mass spectrometry (MS) techniques identified lettucenin A and three novel derivatives. We call these compounds lettucenins A1, B, and B1. Color-dilution analyses revealed these lettucenins as key chromophores in the browning of Iceberg lettuce. A time formation curve showed the accumulation of lettucenins A and B within 40 h after cutting. Thereafter, these structures were degraded to unknown colored compounds. Lettucenin A was verified in five varieties of Lactuca. In contrast to that, lettucenin A was present only at trace levels in five varieties of Cichorium. Therefore, lettucenin A might be used as a chemosystematic marker of the genus Lactuca. PMID:24818869

Mai, Franziska; Glomb, Marcus A

2014-05-21

169

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

Science.gov (United States)

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

170

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

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

A. Alizadeh

2002-04-01

171

Light-Emitting Diodes (LEDs for Miniature Hydroponic Lettuce  

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Full Text Available There is growing concern about food safety, environmental impact, and efficient energy usage in agricultural production systems. Producing lettuce under artificial lighting could be a solution addressing these concerns. Light-emitting diodes (LEDs offer the advantages of a narrow light spectrum, low power consumption, and little heat production. The objective of this study was to determine the effects of different light sources on the growth of miniature “Tom Thumb” butterhead lettuce in a non-circulating hydroponic system. Lettuce seedlings, started in Oasis Horticubes, were transferred to net pots in containers with a hydroponic nutrient solution. The lettuce was grown in a lab under three light treatments—blue LEDs, red LEDs, and fluorescent lights. At the end of the study, fluorescent lights resulted in greater root dry weight than blue LEDs and red LEDs. Total plant dry weight under fluorescent lights was greater than under red LEDs. There were no significant differences in shoot dry weight and plant height among the treatments. Percent partitioning of dry weight to shoots was greatest with red LEDs, followed by blue LEDS, and fluorescent lights. Percent partitioning of dry weight to roots was greatest with fluorescent lights, followed by blue LEDS, and red LEDs. Leaf chlorophyll content was greater under blue LEDs and fluorescent lights than red LEDs. The pH of the nutrient solution of the blue LED and the fluorescent light treatments were greater than the red LED treatment. Electrical conductivity of the nutrient solution of the fluorescent light treatment was greater than the blue LED treatment and the red LED treatment. In conclusion, LEDs could provide an alternative lighting source for miniature lettuce production.

Michelle Lazaro

2013-03-01

172

Impact of Organic Load on Escherichia coli O157:H7 Survival during Pilot-Scale Processing of Iceberg Lettuce with Acidified Sodium Hypochlorite.  

Science.gov (United States)

Chemical sanitizers are routinely used during commercial flume washing of fresh-cut leafy greens to minimize cross-contamination from the water. This study assessed the efficacy of three chlorine treatments against Escherichia coli O157:H7 on iceberg lettuce, in wash water, and on surfaces of a pilot-scale processing line using flume water containing various organic loads. Iceberg lettuce (5.4 kg) was inoculated to contain 10(6) CFU/g of a 4-strain cocktail of nontoxigenic, green fluorescent protein-labeled, ampicillin-resistant E. coli O157:H7 and held for 24 h at 4°C before processing. Lettuce was shredded using a Urschel TransSlicer, step conveyed to a flume tank, washed for 90 s using water alone or one of three different sanitizing treatments (50 ppm of total chlorine either alone or acidified to pH 6.5 with citric acid or T-128) in water containing organic loads of 0, 2.5, 5, or 10% (wt/vol) blended iceberg lettuce, and then dried using a shaker table and centrifugal dryer. Next, three 5.4-kg batches of uninoculated iceberg lettuce were processed identically. Various product (25 g), water (50 ml), and equipment surface swab (100 cm(2)) samples were homogenized in neutralizing buffer, diluted appropriately, and plated on tryptic soy agar containing 0.6% (wt/vol) yeast extract and 100 ppm of ampicillin without prior 0.45- m m membrane filtration to quantify E. coli O157:H7. Organic load negatively impacted the efficacy of all three chlorine treatments (P 5 and 0.9 to 3.7 log CFU/ml for organic loads of 0 and 10%, respectively. Organic load rarely had a significant impact (P citric acid, or chlorine plus T-128 against E. coli O157:H7 on iceberg lettuce. Reduced sanitizer efficacy generally corresponded to changes in total solids, chemical oxygen demand, turbidity, and maximum filterable volume, indicating that these tests may be effective alternatives to the industry standard of oxygen/reduction potential. PMID:25285483

Davidson, Gordon R; Kaminski, Chelsea N; Ryser, Elliot T

2014-10-01

173

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

Scientific Electronic Library Online (English)

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

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

174

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  

Directory of Open Access Journals (Sweden)

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

Alexandre O. Gonçalves

2005-12-01

175

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

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

Zahoor Ahmad Bazai

2006-01-01

176

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

Directory of Open Access Journals (Sweden)

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.

Józef B?kowski

1996-12-01

177

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

Science.gov (United States)

The interest in producing pharmaceutical proteins in a nontoxic plant host has led to the development of an approach to express such proteins in transplastomic lettuce (Lactuca sativa L.). A number of therapeutic proteins and vaccine antigen candidates have been stably integrated into the lettuce plastid genome using biolistic DNA delivery. High levels of accumulation and retention of biological activity suggest that lettuce may provide an ideal platform for the production of biopharmaceuticals. PMID:24599864

Ruhlman, Tracey A

2014-01-01

178

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: English Abstract in spanish La producción hortícola en la Sabana de Bogotá tiene como principales fuentes hídricas al distrito de riego La Ramada y al rio Bogotá, el cual lleva en su cauce materiales contaminantes como metales pesados, provenientes de las diferentes actividades industriales y domésticas de la Sabana. Estos con [...] taminantes afectan la producción de cultivos en esta zona. En el presente estudio, bajo condiciones de laboratorio, se evaluó el efecto del cadmio (Cd) y cromo (Cr) en tres concentraciones (25, 35 y 50 µM L-1), sobre la imbibición, germinación y elongación radical de lechuga (Lactuca sativa var. Batavia), acelga (Beta vulgaris var. cicla "White Ribbed") y espinaca (Spinacia oleracea híbrida 424), tres especies que son ampliamente cultivadas en la zona. Se encontró una susceptibilidad diferente a los dos compuestos metálicos en cada especie. En lechuga, en el último día de la observación, las tres soluciones de Cd disminuyeron el aumento del peso fresco de las semillas (imbibición), mientras este ocurrió en acelga solamente a 25 µM L-1 de Cd. Cadmio afectó la germinación en 46%, 97% y 8% en acelga, lechuga y espinaca, respectivamente; también, este metal redujo la elongación radical hasta un 57%, 89% y 56% en las tres especies, respectivamente. El Cr no mostró efectos tan negativos, pero redujo la germinación de acelga (29%), lechuga (6%) y espinaca (34%), comparado al control Abstract in english The La Ramada district and the Bogota River are the principal water resources used for horticultural crop production on the Bogota Plateau, which contain channel pollutant materials, including heavy metals due to domestic and industrial activities on the Plateau. These materials have effects on crop [...] production in this zone. The present research, under laboratory conditions, aimed to evaluate the effect of three concentrations (25, 35 and 50 µM L-1) of cadmium (Cd) and chromium (Cr) on imbibition, seed germination and root elongation in lettuce (Lactuca sativa var. Batavia), Swiss chard (Beta vulgaris var. cicla "White Ribbed"), and spinach (Spinacia oleracea Hib. 424), three species widely cultivated on the Plateau. The three species used for evaluation showed a differential susceptibility response to Cd and Cr. In lettuce, fresh weight increase (imbibition) was lower with all Cd concentrations at the last day of observation and at 25 µM L-1 of Cd in Swiss chard. Cadmium reduced seed germination by up to 46%, 97% and 8% in Swiss chard, lettuce and spinach, respectively. Also, root elongation decreased in Cd treatments by up to 57%, 89% and 56%, for Swiss chard, lettuce and spinach, respectively. Chromium, which showed fewer negative effects, decreased germination by up to 29% in Swiss chard, 6% in lettuce and 34% in spinach, as compared to the control

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

2013-04-01

179

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

Directory of Open Access Journals (Sweden)

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

Yuni Agung Nugroho

2009-05-01

180

Aceptabilidad de lechuga de hoja fresca troceada, tratada con ácido ascórbico mediante hidroenfriamiento / Acceptability of fresh cut leaf lettuce treated with ascorbic acid applied by hydrocooling  

Scientific Electronic Library Online (English)

Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish Se evaluó el efecto del ácido ascórbico aplicado mediante dos métodos de hidroenfriamiento sobre la aceptabilidad general, sabor y apariencia de lechuga verde de hoja troceada, así como la relación entre el sabor y la apariencia de la lechuga de hoja procesada sobre la aceptabilidad general de este [...] producto. La lechuga de hoja fue hidroenfriada con una solución de ácido ascórbico al 1% mediante inmersión y aspersión, o con agua por inmersión. Se uso como control a lechuga no hidroenfriada. Las soluciones para tratamientos fueron aplicadas a 5 ºC por 2 min, y la lechuga fue luego empacada en bolsas de polietileno impermeables a la humedad, almacenada a 5 ºC por 14 días, y evaluada en los días 1, 7 y 14 de almacenamiento. La aceptabilidad general de la lechuga de hoja procesada (troceada y empacada) estuvo altamente correlacionada con su sabor (R²= 0.85), pero no con su apariencia (R²= 0.39). Todos los tratamientos mantuvieron sus valores de aceptabilidad general y sabor durante el almacenamiento de 14 días (p>0.05). Sin embargo, la lechuga hidroenfriada mediante aspersión con ácido ascórbico y la no hidroenfriada (control) fueron los únicos tratamientos que mantuvieron su apariencia durante el estudio. Es requerida más experimentación con la aplicación de ácido ascórbico mediante hidroenfriamiento para garantizar su utilidad para la conservación de la calidad sensorial de la lechuga de hoja procesada durante su almacenamiento. Abstract in english We assessed the effect of ascorbic acid, applied by two hydrocooling methods, on the overall acceptability, taste and appearance of cut green leaf lettuce, and the relationship between the taste and appearance of processed leaf lettuce regarding the overall acceptability of this product. Leaf lettuc [...] e was hydrocooled with a solution of 1% ascorbic acid by immersion and spraying, or by immersion in water. Non-hydrocooled lettuce was used as control. The treatment solutions were applied at 5 °C for 2 min, and the lettuce was then packed in polyethylene bags, impervious to moisture, stored at 5 °C for 14 days, and evaluated after 1, 7 and 14 days of storage. The overall acceptability of processed leaf lettuce (cut and packed) was highly correlated with its taste (R²= 0.85), but not with its appearance (R²= 0.39). All treatments maintained the overall acceptability values and taste of the lettuce during the 14 days of storage (p> 0.05). However, the lettuce that was hydrocooled by spraying with ascorbic acid, and the non-hydrocooled lettuce (control) were the only treatments that maintained appearance during the study. Further experimentation with the application of ascorbic acid by hydrocooling is required to ensure its usefulness for maintaining the sensory quality of processed leaf lettuce during storage.

Juan Ramón, Esparza-Rivera; Agustín, Navarro Bravo; Patricia, Kendall; Manuel, Fortis Hernández; Pablo, Preciado Rangel; Jorge Armando, Meza Velázquez.

2013-08-13

 
 
 
 
181

Behavior of Shiga Toxigenic Escherichia coli Relevant to Lettuce Washing Processes and Consideration of Factors for Evaluating Washing Process Surrogates.  

Science.gov (United States)

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

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

2014-11-01

182

Fate of [14C]-zineb on lettuce plants  

International Nuclear Information System (INIS)

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

183

Comparison of three fungicide spray advisories for lettuce downy mildew  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Lettuce growers in coastal California have relied mainly on protective fungicide sprays to control downy mildew. Thus, timing of sprays before infection is critical for optimal results. A leaf-wetness-driven, infection-based advisory system, previously developed, did not always perform satisfactorily. In this study, the advisory system was modified by incorporating a pathogen survival component (system 1) or both survival and sporulation components (system 2). These systems were then evaluate...

Wu, B. M.; Subbarao, K. V.; Bruggen, A. H. C.; Koike, S. T.

2001-01-01

184

Quorum Sensing Activity of Enterobacter asburiae Isolated from Lettuce Leaves  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 resolu...

Kok-Gan Chan; Jian Woon Chen; Wai-Fong Yin; Yin Yin Lau; Joanita Sulaiman

2013-01-01

185

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

2008-01-01

186

Toxicity of sodium tungstate to earthworm, oat, radish, and lettuce.  

Science.gov (United States)

Due to unknown effects of the potential exposure of the terrestrial environment to tungsten substances, a series of toxicity studies of sodium tungstate (Na(2) WO(4) ) was conducted. The effect on earthworm (Eisenia fetida) survival and reproduction was examined using Organisation for Economic Co-operation and Development (OECD) Guideline 222. No effect on either endpoint was seen at the highest concentration tested, resulting in a 56-d no-observed-effect concentration (NOEC) of ?586 mg tungsten/kg dry soil (nominal concentrations). The effect of sodium tungstate on emergence and growth of plant species was examined according to OECD Guideline 208: oat (Avena sativa), radish (Raphanus sativus), and lettuce (Lactuca sativa). No effects on emergence, shoot height, and dry shoot weight were observed in oats exposed to the highest concentration, resulting in a 21-d NOEC of ?586 mg tungsten/kg dry soil. The NOECs for radish and lettuce were 65 and 21.7 mg tungsten/kg dry soil (nominal concentrations), respectively. Respective 21-d median effective concentration values (EC50) for radish and lettuce were >586 and 313 mg tungsten/kg dry soil (based on shoot height) (confidence level [CL] -8.5-615); EC25 values were 152 (CL 0-331) and 55 (CL 0-114) mg tungsten/kg dry soil. Results are consistent with the few other tungsten substance terrestrial toxicity studies in the literature. PMID:21805499

Bamford, Josie E; Butler, Alicia D; Heim, Katherine E; Pittinger, Charles A; Lemus, Ranulfo; Staveley, Jane P; Lee, K Brian; Venezia, Carmen; Pardus, Michael J

2011-10-01

187

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

Science.gov (United States)

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 substitute the conventional peat substrate for lettuce cultivation. In addition, this can be proposed as an alternative waste management practice. PMID:19039073

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

2008-12-01

188

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

International Nuclear Information System (INIS)

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

189

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

Science.gov (United States)

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

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

2010-01-01

190

Internalization and dissemination of human norovirus and animal caliciviruses in hydroponically grown romaine lettuce.  

Science.gov (United States)

Fresh produce is a major vehicle for the transmission of human norovirus (NoV) because it is easily contaminated during both pre- and postharvest stages. However, the ecology of human NoV in fresh produce is poorly understood. In this study, we determined whether human NoV and its surrogates can be internalized via roots and disseminated to edible portions of the plant. The roots of romaine lettuce growing in hydroponic feed water were inoculated with 1 × 10(6) RNA copies/ml of a human NoV genogroup II genotype 4 (GII.4) strain or 1 × 10(6) to 2 × 10(6) PFU/ml of animal caliciviruses (Tulane virus [TV] and murine norovirus [MNV-1]), and plants were allowed to grow for 2 weeks. Leaves, shoots, and roots were homogenized, and viral titers and/or RNA copies were determined by plaque assay and/or real-time reverse transcription (RT)-PCR. For human NoV, high levels of viral-genome RNA (10(5) to 10(6) RNA copies/g) were detected in leaves, shoots, and roots at day 1 postinoculation and remained stable over the 14-day study period. For MNV-1 and TV, relatively low levels of infectious virus particles (10(1) to 10(3) PFU/g) were detected in leaves and shoots at days 1 and 2 postinoculation, but virus reached a peak titer (10(5) to 10(6) PFU/g) at day 3 or 7 postinoculation. In addition, human NoV had a rate of internalization comparable with that of TV as determined by real-time RT-PCR, whereas TV was more efficiently internalized than MNV-1 as determined by plaque assay. Taken together, these results demonstrated that human NoV and animal caliciviruses became internalized via roots and efficiently disseminated to the shoots and leaves of the lettuce. PMID:22729543

Dicaprio, Erin; Ma, Yuanmei; Purgianto, Anastasia; Hughes, John; Li, Jianrong

2012-09-01

191

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

Science.gov (United States)

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

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

2011-11-15

192

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-12-15

193

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

Science.gov (United States)

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.

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

194

Sequence diversity in the coat protein gene of Lettuce big-vein associated virus and Mirafiori lettuce big-vein virus infecting lettuce in Brazil Variabilidade genética na porção codificadora para a proteína capsidial do Lettuce big-vein associated virus e Mirafiori lettuce big-vein virus provenientes de alface no Brasil  

Directory of Open Access Journals (Sweden)

Full Text Available Lettuce big vein associated virus (LBVaV and Mirafiori lettuce big vein virus (MLBVV have been found in mixed infection in Brazil causing the lettuce big vein disease. Analysis of part of the coat protein (CP gene of Brazilian isolates of LBVaV collected from lettuce, showed at least 93% amino acid sequence identity with other LBVaV isolates. Genetic diversity among MLBVV CP sequences was higher when compared to LBVaV CP sequences, with amino acid sequence identity ranging between 91% to 100%. Brazilian isolates of MLBVV belong to subgroup A, with one RsaI restriction site on the coat protein gene. There is no indication for a possible geografical origin for the Brazilian isolates of LBVaV and MLBVV.Lettuce big vein associated virus (LBVaV e Mirafiori lettuce big vein virus (MLBVV têm sido encontrados em infecções mistas no Brasil, causando a doença conhecida como engrossamento das nervuras da alface. Análise de parte do gene da proteína capsidial (CP de isolados brasileiros de LBVaV coletados em alface, indicou que estes possuem identidade superior a 93% com isolados coletados em diferentes regiões geográficas. A diversidade genética entre a CP de isolados de MLBVV de alface foi maior comparada às sequências da CP de LBVaV, com a identidade de aminoácidos variando entre 91 a 100%. Os isolados brasileiros de MLBVV pertencem ao subgrupo A, com um único sítio de restrição RsaI no gene da proteína capsidial. Não há indicação para uma provável origem geográfica dos isolados brasileiros de MLBVV e LBVaV.

Márcio Martinello Sanches

2008-06-01

195

Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations  

Science.gov (United States)

In pursuit of our ultimate goal to better understand the prodigious capacity of the marine macroalga Ulva lactuca (sea lettuce) for adsorbing a broad range of dissolved trace metals from seawater, we performed an initial characterization of its surface functional groups. Specifically, the number of distinct functional groups as well as their individual bulk concentrations and acid dissociation constants (pKas) were determined by potentiometric titrations in NaCl solutions of various ionic strengths (I = 0.01-5.0 M), under inert nitrogen atmosphere at 25°C. Depending on the ionic strength, Ulva samples were manually titrated down to pH 2 or 3 with 1 N HCl and then up to pH 10 with 1 N NaOH in steps of 0.1-0.2 units, continuously monitoring pH with a glass combination electrode. Titrations of a dehydrated Ulva standard reference material (BCR-279) were compared with fresh Ulva tissue cultured in our laboratory. A titration in filtered natural seawater was also compared with one in an NaCl solution of equal ionic strength. Equilibrium constants for the ionization of water in NaCl solutions as a function of ionic strength were obtained from the literature. Fits to the titration data ([H]T vs. pH) were performed with the FITEQL4.0 computer code using non-electrostatic 3-, 4-, and 5-site models, either by fixing ionic strength at its experimental value or by allowing it to be extrapolated to zero, while considering all functional group pKas and bulk concentrations as adjustable parameters. Since pKas and bulk concentrations were found to be strongly correlated, the latter were also fixed in some cases to further constrain the pKas. Whereas these calculations are currently ongoing, preliminary results point to three, possibly four, functional groups with pKas of about 4.1, 6.3, and 9.5 at I = 0. Bulk concentrations of the three groups are very similar, about 5-6×10-4 mol/g based on dry weight, which suggests that all are homogeneously distributed over the surface and probably part of a single macromolecular scaffold. Fresh Ulva tissue appears to contain the same three functional groups but at lower concentrations, based on wet weight. The titration in natural seawater was largely dominated by the non-carbonate alkalinity of the solution and could not be robustly modeled. Results of fits with ionic strengths fixed at their experimental values indicate that the pKas of all three groups display prominent Debije-Hückel-type behavior, hence that these acid dissociation reactions involve a different mechanism than metal-proton exchange reactions on mineral surfaces, whose distribution coefficients (i.e., equilibrium constants) generally show a weak ionic strength dependence.

Ebling, A. M.; Schijf, J.

2008-12-01

196

Effect of CO2 levels on nutrient content of lettuce and radish  

Science.gov (United States)

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.

McKeehen, J. D.; Smart, D. J.; Mackowiak, C. L.; Wheeler, R. M.; Nielsen, S. S.; Mitchell, C. A. (Principal Investigator)

1996-01-01

197

Changes in the chlorophyll content in stored lettuce Lactuca sativa L. after pre-harvest foliar application of CaCl2  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of the present investigations was to determine the cumulative effect of foliar treatment of lettuce plants with a CaCl2 solution and the cold-storage period on the level of chlorophylls in the leaves of lettuce cv. ?Omega? (Lactuca sativa L.. Plants were grown in a pot experiment conducted in the greenhouse of the Department of Cultivation and Fertilisation of Horticultural Plants, University of Life Sciences in Lublin. During the growing period, 10 and 20 days before harvest, the plants received foliar application of CaCl2 at the concentrations of 0.1 M and 0.2 M. Control plants were sprayed with water. Some plants were analysed immediately after the harvest; other specimens were cold-stored at a temperature of 4oC for 7 and 14 days. Whole leaves and blades without the midrib were analysed. The results obtained indicated that the foliar application of 0.2M CaCl2 in lettuce resulted in a decrease in the level of chlorophylls in fresh plants, compared with the control. A beneficial cumulative effect of the CaCl2 application and storage period on the chlorophyll level in lettuce leaves was observed in the leaf blades of plants after foliar treatment with the 0.1M CaCl2.solution and cold-stored for 7 and 14 days, in which in- creased levels of chlorophyll “a” and “b” and total chlorophyll, compared with the control, were found.

Irena Perucka

2014-01-01

198

Neural Network Modeling to Predict Shelf Life of Greenhouse Lettuce  

Directory of Open Access Journals (Sweden)

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.

Wei-Chin Lin

2009-04-01

199

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

Science.gov (United States)

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.

Vincevica-Gaile, Zane; Klavins, Maris

2012-12-01

200

Transgenic lettuce seedlings carrying hepatitis B virus antigen HBsAg  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

Jackson, Marcondes; Ekkehard, Hansen.

2008-12-01

 
 
 
 
201

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

DEFF Research Database (Denmark)

A pilot study was conducted to assess the transfer of Escherichia coli from animal slurry fertilizer to lettuce, with E. coli serving as an indicator of fecal contamination and as an indicator for potential bacterial enteric pathogens. Animal slurry was applied as fertilizer to three Danish agricultural fields prior to the planting of lettuce seedlings. At harvest, leaves (25 g) of 10 lettuce heads were pooled into one sample unit (n = 147). Soil samples (100 g) were collected from one field before slurry application and four times during the growth period (n = 75). E. coli was enumerated in slurry, soil, and lettuce on 3M Petrifilm Select E. coli Count Plates containing 16 mg/liter streptomycin, 16 mg/liter ampicillin, or no antimicrobial agent. Selected E. coli isolates (n = 83) originating from the slurry, soil, and lettuce were genotyped by pulsed-field gel electrophoresis (PFGE) to determine the similarity of isolates. The slurry applied to the fields contained 3.0 to 4.5 log CFU/g E. coli. E. coli was found in 36 to 54% of the lettuce samples, streptomycin-resistant E. coli was found in 10.0 to 18.0% of the lettuce samples, and ampicillin-resistant E. coli in 0 to 2.0% of the lettuce samples (the detection limit was 1 log CFU/g). The concentration of E. coli exceeded 2 log CFU/g in 19.0% of the lettuce samples. No E. coli was detected in the soil before the slurry was applied, but after, E. coli was present until the last sampling day (harvest), when 10 of 15 soil samples contained E. coli. A relatively higher frequency of E. coli in lettuce compared with the soil samples at harvest suggests environmental sources of fecal contamination, e.g., wildlife. The higher frequency was supported by the finding of 21 different PFGE types among the E. coli isolates, with only a few common PFGE types between slurry, soil, and lettuce. The frequent finding of fecal-contaminated lettuce indicates that human pathogens such as Salmonella and Campylobacter can be present and represent food safety hazards.

Jensen, Annette Nygaard; Storm, Christina

2013-01-01

202

The case of the salad shooters: intravenous injection of wild lettuce extract.  

Science.gov (United States)

Three young adult drug users obtained wild lettuce and valerian root, prepared a crude aqueous extract of the wild lettuce, and injected the extract i.v. One also injected an alcohol extract of the valerian root. All 3 rapidly became ill with fevers, chills, abdominal pain, flank and back pain, neck stiffness, headache, leucocytosis and mild liver function abnormalities, but recovered over the next 3 d. Various literature and internet sources claim that wild lettuce has opiate properties not demonstrated in this case. PMID:9778767

Mullins, M E; Horowitz, B Z

1998-10-01

203

Assessment of lettuce quality during storage at low relative humidity using Global Stability Index methodology / Avaliação da qualidade da alface durante o armazenamento em baixa umidade relativa usando o Índice Global da Estabilidade  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Durante a pós-colheita a alface é exposta a condições adversas (baixa umidade relativa) que reduzem a qualidade do vegetal. A fim de avaliar sua vida útil, um grande número de índices de qualidade tem que ser analisado, requerendo um cuidadoso delineamento experimental e um longo consumo de tempo. N [...] este trabalho, o método modificado do Índice Global da Estabilidade foi aplicado para estimar a qualidade da alface manteiga a uma baixa umidade relativa durante o armazenamento diferenciando três zonas (interna, média e externa). Os resultados indicaram que, para a zona externa, os índices mais relevantes foram o conteúdo da umidade relativa, conteúdo da água, ácido ascórbico e a contagem total de micro-organismos mesófilos. Para a zona média, foram conteúdo da umidade relativa, conteúdo da água, clorofila total, ácido ascórbico e, para a interna, conteúdo da umidade relativa, água ligada, conteúdo da água e a contagem total de micro-organismos mesófilos. Foi proposto um modelo matemático entre o Índice Global da Estabilidade e qualidade visual geral para cada zona da alface. Ademais, foi aplicada a distribuição de Weibull para estimar o tempo da vida útil do vegetal, o qual foi: 5, 4 e 3 dias para as zonas interna, média e externa, respectivamente. Quando foi estudado o efeito do tempo de armazenamento para cada zona da alface, todos os índices avaliados na zona externa mostraram diferenças significativas (p Abstract in english During postharvest, lettuce is usually exposed to adverse conditions (e.g. low relative humidity) that reduce the vegetable quality. In order to evaluate its shelf life, a great number of quality attributes must be analyzed, which requires careful experimental design, and it is time consuming. In th [...] is study, the modified Global Stability Index method was applied to estimate the quality of butter lettuce at low relative humidity during storage discriminating three lettuce zones (internal, middle, and external). The results indicated that the most relevant attributes were: the external zone - relative water content, water content , ascorbic acid, and total mesophilic counts; middle zone - relative water content, water content, total chlorophyll, and ascorbic acid; internal zone - relative water content, bound water, water content, and total mesophilic counts. A mathematical model that takes into account the Global Stability Index and overall visual quality for each lettuce zone was proposed. Moreover, the Weibull distribution was applied to estimate the maximum vegetable storage time which was 5, 4, and 3 days for the internal, middle, and external zone, respectively. When analyzing the effect of storage time for each lettuce zone, all the indices evaluated in the external zone of lettuce presented significant differences (p

María Roberta, Ansorena; María Victoria, Agüero; María Grabriela, Goñi; Sara, Roura; Alejandra, Ponce; María del Rosario, Moreira; Karina, Di Scala.

2012-06-01

204

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

Science.gov (United States)

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

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

2011-10-01

205

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

Science.gov (United States)

The effect of duckweed (DW) supplementation was evaluated on dry matter intake (DMI), presence and duration of estrus, percentage of ewes repeating estrus and pregnancy rate, as well as the concentration of progesterone (P4) in multiparous crossbred ewes from Pelibuey, Dorper, and Katahdin breeds, fed with Taiwan grass hay (TWH). Eighteen ewes with 39.7±4 kg mean body weight, kept in individual pens, were randomly assigned to one of the following treatments: T1: TWH, T2: TWH plus 200 g DW, T3: TWH plus 300 g DW. The ewes were synchronized with 40 mg fluorogestone acetate (FGA) and 400 UI equine chorionic gonadotropin (eCG). Data were analyzed as a completely randomized design using the GLM procedure. DW supplementation had no effect on dry matter intake (p>0.05); however, a slight decrease of TWH intake was observed as DW supplementation increased. No differences (p>0.05) were found in the beginning of estrus, percentage of ewes presenting it, its duration, or pregnancy rate. There were no differences (p>0.05) on P4 concentration among treatments, or treatmentxperiod interaction (p>0.05). However the period was significant (p<0.01), since the P4 levels increased as time increased after the removal of the FGA device and eCG application. PMID:25049670

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

2012-08-01

206

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

DEFF Research Database (Denmark)

Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. Oocysts were stored approx. six weeks at 4C° before enumeration and approx. two weeks on slides at room temperature. Oocysts were subsequently washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3,268 per 10L water and 11 – 118 oocysts per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water samples from both rivers and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

Petersen, Tobias Boel; Petersen, Heidi Huus

207

Reúso de águas residuárias da piscicultura e da suinocultura na irrigação da cultura da alface / Reuse of wastewater from swine and fish activities in the lettuce culture  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho teve o objetivo de avaliar o desenvolvimento, a produção e a qualidade sanitária da cultura da alface irrigada com águas residuárias originadas da suinocultura e da piscicultura. Os tratamentos avaliados foram: T1 - alface irrigada com água de origem subterrânea e adubação suplementar; [...] T2 - alface irrigada com água residuária de viveiro de peixes alimentados com ração; T3 - alface irrigada com água residuária originária de lagoa de estabilização de dejetos de suínos, e T4 - água de lagoa de cultivo de algas, alimentada com resíduo de biodigestor de dejeto de suíno. Os tratamentos não apresentaram diferenças significativas para altura da alface, diâmetro da cabeça, comprimento da raiz, massa da raiz, massa total da planta, massa fresca e massa seca; os tratamentos T4 e T2 apresentaram os maiores valores para comprimento da maior folha e número de folhas, respectivamente; em geral, as análises foliares e a extração de macro e micronutrientes pela cultura não apresentaram diferenças significativas; ocorreu contaminação de coliformes fecais e totais em todos os tratamentos; não ocorreu contaminação de Escherichia coli em todos os tratamentos; todos os Coeficientes de Uniformidade de Christiansen (CUC) encontrados foram acima de 85%, exceto para o tratamento T3 que foi de 74,05%; ocorreram alterações químicas no solo proporcionais às características das águas utilizadas nos respectivos tratamentos. Abstract in english The objective of this work was to evaluate development, production and sanitary quality of the irrigated lettuce with wastewater from fish and swine activities. The evaluated treatments was: T1 - lettuce irrigated with water from underground origin and supplemental fertilization; T2 - lettuce irriga [...] ted with wastewater from fish activities and fish fed with ration; T3 - lettuce irrigated with wastewater from swine treated in stabilization lagoon; and T4 - lettuce irrigated with effluent from seaweed lagoon, fed with wastewater from swine activities treated with anaerobic reactor. The treatments did not present significant differences for next culture characteristics: height, diameter head, length root, mass root, total mass plant, green mass and dry mass; the treatments T4 and T2 presented the biggest values for length and number leaf, respectively; in general, leaf analyses and extraction of macro and micronutrients by culture did not present significant differences; contamination by fecal coliforms in all treatments occurred; no contamination by Escherichia coli was observed in all treatments; all the Coefficients of Uniformity of Christiansen (CUC) observed were above 85%, except for treatment T3 where was 74%; chemical alterations in the soil occurred proportional to characteristics of waters used in the treatments.

Dirceu, Baumgartner; Silvio C., Sampaio; Tatiana R. da, Silva; Carla R. P. A., Teo; Márcio A., Vilas Boas.

2007-04-01

208

Insecticide residues in head lettuce, cabbage, Chinese cabbage, and broccoli grown in fields.  

Science.gov (United States)

The residues of four insecticides belonging to different families were studied on head lettuce (Lactuca sativa L. var. capitata L.), cabbage (Brassica oleracea Linn. var. capitata DC.), Chinese cabbage (Brassica pekinensis Skeels), and broccoli (Brassica oleracea var. italica) after pesticide application. To reduce application variability, a tank mix of acetamiprid 20% SP, chlorpyrifos 22.5% EC, deltamethrin 2.4% SC, and methomyl 40% SP was applied at recommended and double doses. Initial deposits of all pesticides on head lettuce were higher than those of the other three crops. The residues of chlorpyrifos and deltamethrin were higher than the maximum residue limits (MRLs) at recommended preharvest intervals (PHIs) on head lettuce and Chinese broccoli treated with higher doses. The residues of methomyl on head lettuce also showed the same phenomenon. PMID:24684565

Chen, Miao-Fan; Chen, Jung-Fang; Syu, Jing-Jing; Pei, Chi; Chien, Hsiu-Pao

2014-04-23

209

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

Directory of Open Access Journals (Sweden)

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

Iuliana Cretescu

2014-05-01

210

Bovine biofertilizer and irrigation layers on lettuce development and leaf chlorophyll  

Directory of Open Access Journals (Sweden)

Full Text Available It is necessary and urgent the search by sources of organic fertilizer and decrease the consumption of water for irrigation. In the context, the aim of this study was to evaluate the nutritional effects of the use of bovine biofertilizers incorporated into the soil and of the irrigation in the development of lettuce. The research was developed, using an experimental design in randomized blocks, factorial scheme 6x2, with six levels of fertilization (4 doses of bovine biofertilizer and two witnesses: without fertilizer and mineral fertilizer and two irrigation layers (80 and 100% of reference evapotranspiration with four replications, in the field. The variables analyzed were: height, head diameter, chlorophyll, leaf number, fresh matter and dry matter of plant tops. It was performed by analysis of variance of F test, comparison of means by Tukey test (p <0.05 and polynomial regression. The results showed that the levels of biofertilizer were similar to the mineral control, pointing the possibility to replace them with the dose of 90m3ha-1 more recommendable, and the best water layer, of 80% of the evapotranspiration.

Denise Aparecida Chiconato

2014-02-01

211

Modification of yield and chlorophyll content in leaf lettuce by HPS radiation and nitrogen treatments  

Science.gov (United States)

The potential of realizing high photosynthetic photon flux from radiation by high-pressure sodium (HPS) lamp, alone or in combination with metal halide (MH) plus quartz iodide (QI) incandescent lamps, to support lettuce grow, with or without nitrogen supplement, was investigated. It was found that varying exposures to radiation from combined HPS, MH, and QI lamps influenced dry weight gain and photosynthetic pigment content of hydroponically grown lettuce (Lactuca sativa L.) seedlings.

Mitchell, Cary A.; Leakakos, Tina; Ford, Tameria L.

1991-01-01

212

Quantitative trait loci associated with longevity of lettuce seeds under conventional and controlled deterioration storage conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Lettuce (Lactuca sativa L.) seeds have poor shelf life and exhibit thermoinhibition (fail to germinate) above ?25°C. Seed priming (controlled hydration followed by drying) alleviates thermoinhibition by increasing the maximum germination temperature, but reduces lettuce seed longevity. Controlled deterioration (CD) or accelerated ageing storage conditions (i.e. elevated temperature and relative humidity) are used to study seed longevity and to predict potential seed lifetimes under convent...

Schwember, Andre?s R.; Bradford, Kent J.

2010-01-01

213

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

Science.gov (United States)

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.

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

2010-09-01

214

Consumer acceptance of fresh-cut iceberg lettuce treated with 2% hydrogen peroxide and mild heat.  

Science.gov (United States)

An antibacterial treatment consisting of 2% hydrogen peroxide at 50 degrees C for 60 s was evaluated for its effects on the sensory quality of fresh-cut iceberg lettuce. Treated lettuce was packaged in polyethylene film by a protocol used in the fresh-cut produce industry and then stored along with untreated controls for 3, 10, and 15 days at 5 degrees C. Gas chromatographic analysis confirmed that the desired initial volume (approximately 6 liters) and oxygen gas content (approximately 10%) were maintained during storage. Consumers from the local community who were the primary shoppers for their households and who purchased and ate lettuce regularly evaluated the appearance, color, aroma, flavor, and texture of the lettuce and their overall liking of the lettuce. Forty consumers were recruited to evaluate processing replication 1 on 26 April, and another 40 were chosen to evaluate processing replication 2 on 3 May. Because replication differences were observed in instrumental color measurements and in mean sensory ratings, replications were not pooled for the two test dates. Lettuce purchased for processing replication 2 was considerably greener than that used in replication 1. Overall, the antibacterial treatment was more effective than the control treatment in maintaining sensory quality over 15 days of storage, provided that the lettuce was initially intensely green. Three-fourths of the participants indicated that they would be willing to buy precut packaged lettuce that had already been treated at the packinghouse or processing plant with an antibacterial solution, and of these participants, 62.5% indicated that they would be willing to pay 5 to 10 cents more per bag. PMID:12182471

McWatters, Lk H; Chinnan, M S; Walker, S L; Doyle, M P; Lin, C M

2002-08-01

215

Characterization of Distinct Tombusviruses that Cause Diseases of Lettuce and Tomato in the Western United States.  

Science.gov (United States)

A soilborne disease of lettuce, associated with necrosis and dieback, has been found with increasing frequency in California and Arizona over the last 10 years. An isometric virus, serologically related to Tomato bushy stunt virus (TBSV), was consistently isolated from lettuce plants with these disease symptoms. Back-inoculation to healthy lettuce plants and subsequent reisolation of the virus from symptomatic lettuce leaves suggested that this virus was the causal agent of this disease. A tombusvirus was also associated with a necrosis disease of greenhouse-grown tomatoes in Colorado and New Mexico. Complementary DNA representing the 3' end of viral genomic RNAs recovered from diseased lettuce and tomato plants had identical nucleotide sequences. However, these sequences were divergent (12.2 to 17.1%) from sequences of the previously described strains of TBSV, Petunia asteroid mosaic virus (PAMV), Artichoke mottled crinkle virus, and Carnation Italian ringspot virus. Additional tombusvirus isolates were recovered from diseased lettuce and tomato plants and these were most closely related to the TBSV-cherry strain (synonymous with PAMV) and to Cucumber necrosis virus based on comparison of 3'-end sequences (0.1 to 0.6% and 4.8 to 5.1% divergence, respectively). Western blot analysis revealed that the new tombusvirus isolated from diseased lettuce and tomato plants in the western United States is serologically distinct from previously described tombusvirus species and strains. Based on genomic and serological properties, we propose to classify this virus as a new tombusvirus species and name it Lettuce necrotic stunt virus. PMID:18944038

Obermeier, C; Sears, J L; Liu, H Y; Schlueter, K O; Ryder, E J; Duffus, J E; Koike, S T; Wisler, G C

2001-08-01

216

Predicting the effects of measures to reduce eutrophication in surface water in rural areas - a case study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The effectiveness of measures to reduce nutrient concentrations in surface water was predicted by a combination of a nutrient leaching model for groundwater and a nutrient simulation model for surface water. Scenarios were formulated based on several measures. Different combinations of drainage level and fertilizer use gave slightly different leaching concentrations. Removing duckweed, dredging the total sediment layer, improving the sewage treatment plants, and a combination of these will re...

Hendriks, R. F. A.; Kolk, J. W. H.

1995-01-01

217

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

Science.gov (United States)

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

Shim, Chang Ki; Kim, Min Jeong; Kim, Yong Ki; Jee, Hyeong Jin

2014-01-01

218

Evaluation of lettuce germplasm resistance to gray mold disease for organic cultivations.  

Science.gov (United States)

This study was conducted to evaluate the resistance of 212 accessions of lettuce germplasm to gray mold disease caused by Botrytis cinerea. The lettuce germplasm were composed of five species: Lactuca sativa (193 accessions), L. sativa var. longifolia (2 accessions), L. sativa var. crispa (2 accessions), L. saligna (2 accessions), and L. serriola (1 accession); majority of these originated from Korea, Netherlands, USA, Russia, and Bulgaria. After 35 days of spray inoculation with conidial suspension (3×10(7) conidia/ml) of B. cinerea on the surface of lettuce leaves, tested lettuce germplasm showed severe symptoms of gray mold disease. There were 208 susceptible accessions to B. cinerea counted with 100% of disease incidence and four resistant accessions, IT908801, K000598, K000599, and K021055. Two moderately resistant accessions of L. sativa, K021055 and IT908801, showed 20% of disease incidence of gray mold disease at 45 days after inoculation; and two accessions of L. saligna, K000598 and K000599, which are wild relatives of lettuce germplasm with loose-leaf type, showed complete resistance to B. cinerea. These four accessions are candidates for breeding lettuce cultivars resistant to gray mold disease. PMID:25288990

Shim, Chang Ki; Kim, Min Jeong; Kim, Yong Ki; Jee, Hyeong Jin

2014-03-01

219

Short communication. Effect of deficit irrigation on curly lettuce grown under semiarid conditions  

Energy Technology Data Exchange (ETDEWEB)

Field experiments were conducted to characterize the effects of deficit irrigation on curly lettuce (Lactuca sativa var. Crispa cv. Bohemia) evapotranspiration, water use efficiency, marketable yield, yield components and mineral contents. The experiments were performed under semiarid climatic conditions in Erzurum province (east of Turkey) in the summer periods of 2005 and 2006. Irrigation water levels were selected to be 100% of usable soil water in full irrigation treatment (control) (T-100) and 80%, 60%, 40% and 20% of usable soil water in deficit irrigation treatments (T-80, T-60, T-40 and T- 20, respectively). Average seasonal evapotranspiration was 232 mm in T-100 and 121 mm in T-20. Average marketable yield was 39.49 Mg ha{sup -}1 in T-100 and 14.57 Mg ha{sup -}1 in T-20. A linear relationship (y=0.23x-13.97; R{sup 2}0.94) was found between seasonal evapotranspiration (x) and marketable plant yield (y). According to the regression equation, the yield response factor (k{sub y}) was found to be 1.39, and the coefficient of determination 0.91. Average water use efficiency was 168.88 kg ha{sup -}1 mm{sup -}1 in T-100 and 117.39 kg ha{sup -}1 mm{sup -}1 in T-20. The lowest plant length, width, steam diameter, leaf number, macro and micro element content values were obtained for T-20 in both years. (Author) 21 refs.

Kuslu, Y.; Dursun, A.; Sahin, U.; Kiziloglu, F. M.; Turan, M.

2008-07-01

220

Quorum Sensing Activity of Enterobacter asburiae Isolated from Lettuce Leaves  

Directory of Open Access Journals (Sweden)

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.

Kok-Gan Chan

2013-10-01

 
 
 
 
221

Quorum sensing activity of Enterobacter asburiae isolated from lettuce leaves.  

Science.gov (United States)

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. PMID:24152877

Lau, Yin Yin; Sulaiman, Joanita; Chen, Jian Woon; Yin, Wai-Fong; Chan, Kok-Gan

2013-01-01

222

Does iodine biofortification affect oxidative metabolism in lettuce plants?  

Science.gov (United States)

Plants produce low levels of reactive oxygen species (ROS), which form part of basic cell chemical communication; however, different types of stress can lead to an overexpression of ROS that can damage macromolecules essential for plant growth and development. Iodine is vital to human health, and iodine biofortification programs help improve the human intake through plant consumption. This biofortification process has been shown to influence the antioxidant capacity of lettuce plants, suggesting that the oxidative metabolism of the plant may be affected. The results of this study demonstrate that the response to oxidative stress is variable and depends on the form of iodine applied. Application of iodide (I(-)) to lettuce plants produces a reduction in superoxide dismutase (SOD) activity and an increase in catalase (CAT) and L-galactono dehydrogenase enzyme activities and in the activity of antioxidant compounds such as ascorbate (AA) and glutathione. This did not prove a very effective approach since a dose of 80 ?M produced a reduction in the biomass of the plants. For its part, application of iodate (IO (3) (-) ) produced an increase in the activities of SOD, ascorbate peroxidase, and CAT, the main enzymes involved in ROS detoxification; it also increased the concentration of AA and the regenerative activities of the Halliwell-Asada cycle. These data confirm the non-phytotoxicity of IO (3) (-) since there is no lipid peroxidation or biomass reduction. According to our results, the ability of IO (3) (-) to induce the antioxidant system indicates that application of this form of iodine may be an effective strategy to improve the response of plants to different types of stress. PMID:20838926

Blasco, Begoña; Ríos, Juan Jose; Leyva, Rocío; Cervilla, Luis Miguel; Sánchez-Rodríguez, Eva; Rubio-Wilhelmi, María Mar; Rosales, Miguel Angel; Ruiz, Juan Manuel; Romero, Luis

2011-09-01

223

EFFECTS OF TRICHODERMA HARZIANUM ON LETTUCE IN PROTECTED CULTIVATION  

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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.

Ugur Bal

2008-07-01

224

Efeitos na fotossíntese e área foliar de cultivares de alface inoculadas mecanicamente com patótipos do Lettuce mosaic virus e Lettuce mottle virus Effects on photosynthesis and foliar area of lettuce cultivar mechanically inoculated with Lettuce mosaic virus pathotypes and Lettuce mottle virus  

Directory of Open Access Journals (Sweden)

Full Text Available Levantamentos realizados no estado de São Paulo indicaram a ocorrência isolada e em infecções mistas do Lettuce mosaic virus (LMV e do Lettuce mottle virus (LeMoV em plantas de alface (Lactuca sativa. O presente trabalho teve como objetivo estudar os efeitos da infecção isolada e mista entre o LMV (patótipos II e IV e o LeMoV, em cultivares de alface suscetível (White Boston e tolerante (Elisa - gene mol¹ ao LMV patótipo II. As plantas foram inoculadas via extrato vegetal tamponado com isolados de LMV-II, LMV-IV e LeMoV separadamente e em diferentes combinações, com intervalo de 24 h ou simultaneamente com os dois vírus. As plantas infetadas foram analisadas utilizando-se hospedeiras diferenciais para o LMV e o LeMoV, e no caso do LMV pelo teste sorológico de PTA-ELISA. Nas avaliações de peso fresco e seco, área foliar e teor de clorofila, observou-se que a cultivar White Boston foi a mais afetada por ambos os vírus. As infecções mistas e isoladas na cultivar Elisa causaram efeitos semelhantes, provavelmente devido a presença do gene mo1¹ de tolerância ao LMV-II. O isolado LMV-IV foi considerado o mais agressivo nestas cultivares quando comparado ao LMV-II e o LeMoV.A survey of virus isolates causing mosaic in lettuce (Lactuca sativa in the state of São Paulo, Brazil, indicated the occurrence of Lettuce mosaic virus (LMV and Lettuce mottle virus (LeMoV alone or in mixed infections. The objective of this work was to study the effects of single and mixed infections between LMV (pathotypes II and IV and LeMoV in susceptible (White Boston and tolerant (Elisa, mo1¹ gene lettuce cultivars. Plants were sap-inoculated with LMV-II, LMV-IV and LeMoV, in single infections and in different combinations, with either a 24 h interval between the two viruses or simultaneously. Plants were tested for the presence of LMV and LeMoV using differential hosts and, in the case of LMV, the serological test (PTA-ELISA was used. In the evaluations of fresh and dry weight, leaf area and chlorophyll content, the White Boston cultivar was observed to be the most affected by both viruses. This cultivar's response to single and mixed infections was similar, probably due to the presence of the mo1¹ gene which confers tolerance to LMV-II. When compared to LMV-IV and LeMoV, LMV-IV was the most aggressive isolate.

Adriana S Jadão

2004-02-01

225

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

Science.gov (United States)

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.

Mickens, Matthew A.

2012-01-01

226

Green remediation of tetracyclines in soil-water systems  

Directory of Open Access Journals (Sweden)

Full Text Available The presence of tetracyclines in soil and surface water is an emerging concern. The present study was undertaken to investigate remediation of tetracylines (tetracycline (TC, oxytetracycline (OTC and chlortetracycline (CTC from aqueous solution using vetiver grass, water lettuce, and sunflower and root exudates of water lettuce, sunflower and from soil by tomato, Indian mustard and carrot plant. The data of this study denote that vetiver grass, water lettuce, sunflower remedy tetracyclines from water. The remediation % after 63 days of treatment was 87-61 for TC; 88-68 for OTC and 87-68 for CTC. The remediation of tetracyclines at lower concentration of antibiotics in presence of root exudates of water lettuce and sunflower was more than 99% and remediation was faster than water lettuce or sunflower. The remediation of tetracyclines from aqueous solution may be due to oxidation of-OH group(s of tetracycline through a process that is thought to involve reactive oxygen intermediates and/or role of peroxidase enzyme. The plant crops viz., tomato, Indian mustard and carrot can remedy 41%-72% of amended tetracyclines. The maximum bioaccumulation of TC and CTC was in Indian mustard and OTC was maximally bioaccumulated in tomato.  

Om Prakash Bansal

2013-12-01

227

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

DEFF Research Database (Denmark)

Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. Oocysts were stored approx. six weeks at 4C° before enumeration and approx. two weeks on slides at room temperature. Oocysts were subsequently washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3,268 per 10L water and 11 – 118 oocysts per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water samples from both rivers and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

Petersen, Tobias B; Petersen, Heidi H.

228

Oxygenated phosphine fumigation for control of Epiphyas postvittana (Lepidoptera: Tortricidae) eggs on lettuce.  

Science.gov (United States)

Light brown apple moth, Epiphyas postvittana (Walker), is a quarantined pest in most countries. Its establishment in California and potential spread to other parts of the state and beyond make it urgent to develop effective postharvest treatments to control the pest on fresh commodities. Fumigation with cylindered phosphine at low temperature has emerged to be a practical methyl bromide alternative treatment for postharvest pest control on fresh commodities. However, its use to control E. postvittana eggs on sensitive commodities such as lettuce is problematic. E. postvittana eggs are tolerant of phosphine and long phosphine treatment also injures lettuce. In the current study, E. postvittana eggs were subjected to oxygenated phosphine fumigations to develop an effective treatment at a low storage temperature of 2 degrees C. In addition, soda lime as a CO2 absorbent was tested to determine its effects in reducing and preventing injuries to lettuce associated with phosphine fumigations. Three-day fumigation with 1,000 ppm phosphine under 60% O2 achieved 100% mortality of E. postvittana eggs in small-scale laboratory tests. In the presence of the CO2 absorbent, a 3-d large-scale fumigation of lettuce with 1,700 ppm phosphine under 60% O2 resulted in a relative egg mortality of 99.96% without any negative effect on lettuce quality. The 3-d fumigation treatment without the CO2 absorbent, however, resulted in significant injuries to lettuce and consequential quality reductions. The study demonstrated that oxygenated phosphine fumigation has the potential to control E. postvittana eggs and the CO2 absorbent has the potential to prevent injuries and quality reductions of lettuce associated with long-term oxygenated phosphine fumigation. PMID:25195424

Liu, Samuel S; Liu, Yong-Biao; Simmons, Gregory S

2014-08-01

229

ROLE OF PH IN THE ACCUMULATION OF LEAD AND NICKEL BY COMMON DUCKWEED (LEMNA MINOR  

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Full Text Available Heavy metals are the most common non-biodegradable pollutants. Various remediation methods have been used for the treatment of heavy metal contaminated water. However, phytoremediation technology is currently being used due to its economically feasible and ecologically viable advantages. The aim of this study was to examine the role of pH in the accumulation capacity of Lemna minor in Pb and Ni contaminated water. The removal rate of Pb and Ni from L. minor was 99.99% and 99.30% respectively, after 28 days of exposure to the 10 mgl-1 Pb and Ni contaminated water at pH 5-6 and pH 6 respectively. // //

Leela Kaur

2012-11-01

230

ROLE OF PH IN THE ACCUMULATION OF LEAD AND NICKEL BY COMMON DUCKWEED (LEMNA MINOR  

Directory of Open Access Journals (Sweden)

Full Text Available Heavy metals are the most common non-biodegradable pollutants. Various remediation methods have been used for the treatment of heavy metal contaminated water. However, phytoremediation technology is currently being used due to its economically feasible and ecologically viable advantages. The aim of this study was to examine the role of pH in the accumulation capacity of Lemna minor in Pb and Ni contaminated water. The removal rate of Pb and Ni from L. minor was 99.99% and 99.30% respectively, after 28 days of exposure to the 10 mgl-1 Pb and Ni contaminated water at pH 5-6 and pH 6 respectively. // //

Leela Kaur

2012-12-01

231

Consórcios alface-cenoura e alface-rabanete sob manejo orgânico / Intercropping of lettuce-carrot and lettuce-radish under organic management  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Dois experimentos foram conduzidos, por dois anos consecutivos, em Seropédica, RJ, com o objetivo de avaliar o desempenho agronômico dos consórcios das cultivares de alface 'Regina 71' (lisa) e 'Verônica' (crespa) com cenoura 'Brasília' e rabanete 'Híbrido nº 19', sob manejo orgânico, assim como det [...] erminar as quantidades de macronutrientes exportadas. O delineamento experimental usado foi o de blocos ao acaso, com quatro repetições. No primeiro experimento, os tratamentos consistiram de alface crespa em consórcio com cenoura, alface crespa em consórcio com rabanete e os cultivos solteiros. No segundo experimento, usou-se alface lisa em lugar da crespa. Nos consórcios entre cenoura e alface crespa ou lisa, foram observados índices de uso eficiente da terra, superiores a 1,60. Nos consórcios de rabanete com alface, crespa ou lisa, esses índices foram de 1,54 e 1,27, respectivamente. As quantidades de nutrientes extraídas do sistema pelos produtos colhidos foram inferiores aos aportes efetuados, evidenciando a viabilidade de qualquer dos consórcios avaliados. Abstract in english Two experiments were carried out, in two consecutive years, at Seropédica, RJ, Brazil, aiming to evaluate the agronomic performance of intercropping of lettuce cvs. Regina 71 (smooth leaf) and Verônica (crisp leaf) with carrot (cv. Brasília) and radish (cv. Hybrid number 19), under organic managemen [...] t. The amount of nutrients exported from the system by harvesting was also evaluated. The experimental design used was of completely randomized blocks, with four replications. In the first experiment, treatments consisted of lettuce with crisp leaves intercropped with carrot, lettuce with crisp leaves intercropped with radish and sole crops. In the second experiment, lettuce with smooth leaves was used instead of lettuce with crisp leaves. Intercropping of carrot and lettuce, with crisp or smooth leaf, presented land equivalent ratios higher than 1.60. Intercropping of radish and lettuce, with crisp or smooth leaf, presented land equivalent ratios of 1.54 and 1.27, respectively. Besides, the amounts of nutrients extracted by harvested products were lower than the inputs, pointing out the viability of the tested intercroppings.

Ailena Sudo, Salgado; José Guilherme Marinho, Guerra; Dejair Lopes de, Almeida; Raul de Lucena Duarte, Ribeiro; José Antonio Azevedo, Espindola; José Aparício de Aquino, Salgado.

232

Economic analysis of organic greenhouse lettuce production in Turkey / Análise econômica da produção orgânica de alface em estufas na Turquia  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Preocupações sanitárias e ambientais têm atraído a atenção para a prática da agricultura orgânica como meio de proteger o balanço ambiental e produzir sem danificar o ambiente. Este estudo objetiva determinar a viabilidade econômica da produção em estufa da alface (Latuca sativa L.) em um ensaio de [...] campo, a fim de incentivar a produção orgânica de vegetais na área de preservação do Reservatório Tahtali, projetado como o único recurso hídrico de Izmir, a terceira maior cidade da Turquia. Uma estufa de tubos galvanizados (384 m²), ancorados e cobertos com polietileno, foi analisada para identificar procedimentos operacionais padronizados e determinar custos unitários de construção e operação. Alfaces orgânicas foram produzidas no outono de 2001-2002, testando diferentes aplicações de sobras compostadas e esterco de granja avícola como fertilizantes orgânicos (30 e 50 t ha-1), com ou sem a adição de fertilizantes comerciais bacterianos ou algais. A análise econômica foi feita de acordo com as quantidades de fertilizantes utilizadas. A determinação da lucratividade foi feita com base na análise de dados de custos, produtividade e preço. O lucro líquido obtido da produção orgânica de alface em estufa variou entre US$ 0.376 e US$ 0.901 m-2. Abstract in english Health issues and environmental concerns have drawn the attention to organic agriculture aiming to protect the natural balance and to produce without damaging the environment. This study aims determining economic feasibility of organic greenhouse lettuce (Lactuca sativa L.) in an on farm trial, to f [...] oster organic greenhouse vegetable production in the preservation area of Tahtali Dam, projected as the sole water resource of Izmir, Turkey's third largest. A 384 m² greenhouse, constructed of galvanized metal tubing anchored and covered with a polyethylene was analyzed to identify typical operation procedures, and to determine unitary construction and operation cost. Organic lettuces were produced during autumn season of 2001-2002, testing different organic fertilizer applications, including two rates of farmyard and poultry manure (30 and 50 t ha-1) with and without two organic fertilizers based on either bacteria or algae. Economical analysis was performed according to different organic fertilizer applications. Cost, yield, and price data were analyzed to determine the profitability of a typical operation. Net return obtained from organic lettuce growing ranged between us $ 0.376 and us $ 0.901 m-2, as a result of different fertilizer applications.

Sait, Engindeniz; Yuksel, Tuzel.

233

Economic analysis of organic greenhouse lettuce production in Turkey / Análise econômica da produção orgânica de alface em estufas na Turquia  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Preocupações sanitárias e ambientais têm atraído a atenção para a prática da agricultura orgânica como meio de proteger o balanço ambiental e produzir sem danificar o ambiente. Este estudo objetiva determinar a viabilidade econômica da produção em estufa da alface (Latuca sativa L.) em um ensaio de [...] campo, a fim de incentivar a produção orgânica de vegetais na área de preservação do Reservatório Tahtali, projetado como o único recurso hídrico de Izmir, a terceira maior cidade da Turquia. Uma estufa de tubos galvanizados (384 m²), ancorados e cobertos com polietileno, foi analisada para identificar procedimentos operacionais padronizados e determinar custos unitários de construção e operação. Alfaces orgânicas foram produzidas no outono de 2001-2002, testando diferentes aplicações de sobras compostadas e esterco de granja avícola como fertilizantes orgânicos (30 e 50 t ha-1), com ou sem a adição de fertilizantes comerciais bacterianos ou algais. A análise econômica foi feita de acordo com as quantidades de fertilizantes utilizadas. A determinação da lucratividade foi feita com base na análise de dados de custos, produtividade e preço. O lucro líquido obtido da produção orgânica de alface em estufa variou entre US$ 0.376 e US$ 0.901 m-2. Abstract in english Health issues and environmental concerns have drawn the attention to organic agriculture aiming to protect the natural balance and to produce without damaging the environment. This study aims determining economic feasibility of organic greenhouse lettuce (Lactuca sativa L.) in an on farm trial, to f [...] oster organic greenhouse vegetable production in the preservation area of Tahtali Dam, projected as the sole water resource of Izmir, Turkey's third largest. A 384 m² greenhouse, constructed of galvanized metal tubing anchored and covered with a polyethylene was analyzed to identify typical operation procedures, and to determine unitary construction and operation cost. Organic lettuces were produced during autumn season of 2001-2002, testing different organic fertilizer applications, including two rates of farmyard and poultry manure (30 and 50 t ha-1) with and without two organic fertilizers based on either bacteria or algae. Economical analysis was performed according to different organic fertilizer applications. Cost, yield, and price data were analyzed to determine the profitability of a typical operation. Net return obtained from organic lettuce growing ranged between us $ 0.376 and us $ 0.901 m-2, as a result of different fertilizer applications.

Sait, Engindeniz; Yuksel, Tuzel.

2006-06-01

234

Economic analysis of organic greenhouse lettuce production in Turkey Análise econômica da produção orgânica de alface em estufas na Turquia  

Directory of Open Access Journals (Sweden)

Full Text Available Health issues and environmental concerns have drawn the attention to organic agriculture aiming to protect the natural balance and to produce without damaging the environment. This study aims determining economic feasibility of organic greenhouse lettuce (Lactuca sativa L. in an on farm trial, to foster organic greenhouse vegetable production in the preservation area of Tahtali Dam, projected as the sole water resource of Izmir, Turkey's third largest. A 384 m² greenhouse, constructed of galvanized metal tubing anchored and covered with a polyethylene was analyzed to identify typical operation procedures, and to determine unitary construction and operation cost. Organic lettuces were produced during autumn season of 2001-2002, testing different organic fertilizer applications, including two rates of farmyard and poultry manure (30 and 50 t ha-1 with and without two organic fertilizers based on either bacteria or algae. Economical analysis was performed according to different organic fertilizer applications. Cost, yield, and price data were analyzed to determine the profitability of a typical operation. Net return obtained from organic lettuce growing ranged between us $ 0.376 and us $ 0.901 m-2, as a result of different fertilizer applications.Preocupações sanitárias e ambientais têm atraído a atenção para a prática da agricultura orgânica como meio de proteger o balanço ambiental e produzir sem danificar o ambiente. Este estudo objetiva determinar a viabilidade econômica da produção em estufa da alface (Latuca sativa L. em um ensaio de campo, a fim de incentivar a produção orgânica de vegetais na área de preservação do Reservatório Tahtali, projetado como o único recurso hídrico de Izmir, a terceira maior cidade da Turquia. Uma estufa de tubos galvanizados (384 m², ancorados e cobertos com polietileno, foi analisada para identificar procedimentos operacionais padronizados e determinar custos unitários de construção e operação. Alfaces orgânicas foram produzidas no outono de 2001-2002, testando diferentes aplicações de sobras compostadas e esterco de granja avícola como fertilizantes orgânicos (30 e 50 t ha-1, com ou sem a adição de fertilizantes comerciais bacterianos ou algais. A análise econômica foi feita de acordo com as quantidades de fertilizantes utilizadas. A determinação da lucratividade foi feita com base na análise de dados de custos, produtividade e preço. O lucro líquido obtido da produção orgânica de alface em estufa variou entre US$ 0.376 e US$ 0.901 m-2.

Sait Engindeniz

2006-06-01

235

Teores de nutrientes na alface irrigada com água residuária aplicada por sistemas de irrigação / Nutrients levels in lettuce irrigated with wastewater applied by irrigation systems  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Desenvolveu-se este trabalho para avaliar a composição química da parte aérea da alface, cv. Elisa, irrigada com água residuária tratada com leitos cultivados com macrófitas e água de um depósito de fonte hídrica superficial, cultivada em Latossolo Vermelho Distroférrico, utilizando-se dos sistemas [...] de irrigação por aspersão convencional, gotejamento subterrâneo e superficial. O experimento compreendeu o período de 17-8 a 3-10-2001, e as análises químicas da alface foram realizadas aos 47 dias após o transplantio das mudas em campo. A parte aérea da alface foi analisada quanto ao teor de nitrogênio total, nitrato, fósforo, potássio, cálcio, magnésio, enxofre, ferro, manganês, cobre, zinco, sódio, boro, cobalto e molibdênio. O sódio e o enxofre apresentaram teores maiores que o máximo adequado na parte aérea da alface e o magnésio menor, enquanto para os demais elementos químicos foram normais e adequados, considerando os padrões para plantas bem nutridas, não sendo influenciados pelo tipo de água. O sódio foi o elemento químico que apresentou a maior elevação na parte aérea nos tratamentos irrigados com água residuária, apresentando diferença significativa em relação à água do depósito superficial nos três sistemas de irrigação. A utilização dos diferentes sistemas de irrigação para aplicação de água residuária tratada com leitos cultivados com macrófitas não interferiu no teor de nutrientes na parte aérea. Abstract in english A trial was carried out to evaluate the chemical composition in the aerial part of lettuce, cv. 'Elisa', irrigated with wastewater treated with constructed wetland and source deposit water, grown on a Rhodic Hapludox Soil, using the irrigation systems sprinkle, subsurface drip and surface drip irrig [...] ation. The experiment was carried out from August 17th to October 3rd of 2001 and the chemical analyses of the lettuce were accomplished to 47 days after transplanting of the seedling. The aerial part of the lettuce was analyzed as for the levels of total nitrogen, nitrate, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, sodium, boron, cobalt and molybdenum. The sodium and the sulfur presented higher levels than the maximum suitable in the aerial part of the lettuce and the smallest level of magnesium, while other chemical elements analyzed were normal and appropriate considering the standard for well-nourished plants, not being influenced by the water type. The sodium was the chemical element that presented the highest levels in the aerial part of the lettuce in the treatments irrigated with wastewater, presenting significant difference in relationship to the treatments irrigated with source deposit water in the three irrigation systems. The use of the different irrigation systems by the application of wastewater treated with constructed wetland did not interfere in the levels of nutrients in the aerial part of the lettuce.

Delvio, Sandri; Edson E., Matsura; Roberto, Testezlaf.

236

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  

Directory of Open Access Journals (Sweden)

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. The aerial part of the lettuce was analyzed as for the levels of total nitrogen, nitrate, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, sodium, boron, cobalt and molybdenum. The sodium and the sulfur presented higher levels than the maximum suitable in the aerial part of the lettuce and the smallest level of magnesium, while other chemical elements analyzed were normal and appropriate considering the standard for well-nourished plants, not being influenced by the water type. The sodium was the chemical element that presented the highest levels in the aerial part of the lettuce in the treatments irrigated with wastewater, presenting significant difference in relationship to the treatments irrigated with source deposit water in the three irrigation systems. The use of the different irrigation systems by the application of wastewater treated with constructed wetland did not interfere in the levels of nutrients in the aerial part of the lettuce.

Delvio Sandri

2006-04-01

237

Occurrence of Cryptosporidiumspp. oocysts in low quality water and on vegetables in Kumasi, Ghana.  

DEFF Research Database (Denmark)

Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period of, September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. After approximately six weeks of storage at 4C°, analysis and additional storage on slides, oocysts were washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes after. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3268 per 10 L water and 11 – 118 oocyst per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

Petersen, Tobias Boel; Petersen, Heidi Huus

238

Occurrence of Cryptosporidiumspp. oocysts in low quality water and on vegetables in Kumasi, Ghana  

DEFF Research Database (Denmark)

Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period of, September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. After approximately six weeks of storage at 4C°, analysis and additional storage on slides, oocysts were washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes after. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3268 per 10 L water and 11 – 118 oocyst per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

Petersen, T. B.; Petersen, H. H.

2014-01-01

239

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

DEFF Research Database (Denmark)

Protozoan parasites belonging to the genus Cryptosporidium are transmitted e.g. by food and water and may cause severe diarrhoea, dehydration, weight loss and malnutrition. Ingestion of 10 oocysts can lead to infection and pathogenic symptoms. Thus, to characterize Cryptosporidium spp. contamination level of river water, irrigation water and lettuce, 10L of water and 16 lettuce samples were collected four times in the period of, September – October 2013, with weekly intervals from six sample sites in and around Kumasi, Ghana. Oocysts were purified from water by sedimentation for 2 x 48 hours or pulsifying of lettuce followed by immunomagnetic separation and quantification by immunofluorescence microscopy, with sensitivities of 2 and 9%, respectively. After approximately six weeks of storage at 4C°, analysis and additional storage on slides, oocysts were washed off the slides and attempts to characterize Cryptosporidium spp. positive samples were done by PCR amplification and sequencing of the SSU rRNA, the HSP70 and the GP60 genes after. Cryptosporidium oocysts were found in 75% of the water samples and on 43% of the lettuce with concentrations of 53 – 3268 per 10 L water and 11 – 118 oocyst per 15 g of lettuce. Positive water samples on one or more occasions were demonstrated in all water and farm sites while all farms had positive lettuce samples on all occasions. Rainfall seemingly lowered the concentration of oocysts in water but not on lettuce. Molecular characterization of Cryptosporidium positive samples was unsuccessful, thus no conclusions can be drawn concerning sources of contamination. Nevertheless, the detection of high prevalence and concentration levels of Cryptosporidium oocysts on vegetables consumed raw and in water with direct contact to humans entails a potential risk of infection in humans. Implementation of preventive measures based on this study should be considered and actions taken accordingly.

Petersen, T. B.; Petersen, H. H.

2014-01-01

240

Sensory quality attributes of lettuce obtained using different harvesting performance systems  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The objective of this study was to determine the best lettuce cultivar (American 'Graciosa', 'Vanda', 'Marcela' and 'Lavínia') harvesting method. Therefore, quality and shelf-life were evaluated using sensory analyses. Lettuce heads was harvested with the root on by the producer, so that they were c [...] ut in different ways in the laboratory. The samples were stored in a cold chamber at 10 °C and 80% ± 2% of relative humidity for nine days, and the sensorial analyses were performed according to Qualitative Descriptive Analysis method on days 1, 3, 6, and 9 of storage by twelve trained testers. The results were evaluated by variance analysis, principal component analysis, and the Tukey test with a reliability of 95%. The results indicate that there was a reduction in the quality of lettuce between the 1st and the 5th day of storage and that after the sixth day of storage the lettuce samples were considered unfit for consumption, except for the 'Lavínia' lettuce cultivar with root and cut treatment 2. On the ninth day of storage all samples were considered inappropriate for consumption.

Denize Cristine Rodrigues de, Oliveira; Paulo Ademar Martins, Leal; Sylvio Luís, Honório; Eveline Kássia Braga, Soares.

 
 
 
 
241

Sensory quality attributes of lettuce obtained using different harvesting performance systems  

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Full Text Available The objective of this study was to determine the best lettuce cultivar (American 'Graciosa', 'Vanda', 'Marcela' and 'Lavínia' harvesting method. Therefore, quality and shelf-life were evaluated using sensory analyses. Lettuce heads was harvested with the root on by the producer, so that they were cut in different ways in the laboratory. The samples were stored in a cold chamber at 10 °C and 80% ± 2% of relative humidity for nine days, and the sensorial analyses were performed according to Qualitative Descriptive Analysis method on days 1, 3, 6, and 9 of storage by twelve trained testers. The results were evaluated by variance analysis, principal component analysis, and the Tukey test with a reliability of 95%. The results indicate that there was a reduction in the quality of lettuce between the 1st and the 5th day of storage and that after the sixth day of storage the lettuce samples were considered unfit for consumption, except for the 'Lavínia' lettuce cultivar with root and cut treatment 2. On the ninth day of storage all samples were considered inappropriate for consumption.

Denize Cristine Rodrigues de Oliveira

2013-06-01

242

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

Science.gov (United States)

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

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

2011-07-01

243

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

International Nuclear Information System (INIS)

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

244

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

Science.gov (United States)

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.

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

245

Sensory quality attributes of lettuce obtained using different harvesting performance systems  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The objective of this study was to determine the best lettuce cultivar (American 'Graciosa', 'Vanda', 'Marcela' and 'Lavínia') harvesting method. Therefore, quality and shelf-life were evaluated using sensory analyses. Lettuce heads was harvested with the root on by the producer, so that they were c [...] ut in different ways in the laboratory. The samples were stored in a cold chamber at 10 °C and 80% ± 2% of relative humidity for nine days, and the sensorial analyses were performed according to Qualitative Descriptive Analysis method on days 1, 3, 6, and 9 of storage by twelve trained testers. The results were evaluated by variance analysis, principal component analysis, and the Tukey test with a reliability of 95%. The results indicate that there was a reduction in the quality of lettuce between the 1st and the 5th day of storage and that after the sixth day of storage the lettuce samples were considered unfit for consumption, except for the 'Lavínia' lettuce cultivar with root and cut treatment 2. On the ninth day of storage all samples were considered inappropriate for consumption.

Denize Cristine Rodrigues de, Oliveira; Paulo Ademar Martins, Leal; Sylvio Luís, Honório; Eveline Kássia Braga, Soares.

2013-06-01

246

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

Science.gov (United States)

Transgenic plastids offer unique advantages in plant biotechnology, including high-level foreign protein expression. However, broad application of plastid genome engineering in biotechnology has been largely hampered by the lack of plastid transformation systems for major crops. Here we describe the development of a plastid transformation system for lettuce, Lactuca sativa L. cv. Cisco. The transforming DNA carries a spectinomycin-resistance gene (aadA) under the control of lettuce chloroplast regulatory expression elements, flanked by two adjacent lettuce plastid genome sequences allowing its targeted insertion between the rbcL and accD genes. On average, we obtained 1 transplastomic lettuce plant per bombardment. We show that lettuce leaf chloroplasts can express transgene-encoded GFP to approximately 36% of the total soluble protein. All transplastomic T0 plants were fertile and the T1 progeny uniformly showed stability of the transgene in the chloroplast genome. This system will open up new possibilities for the efficient production of edible vaccines, pharmaceuticals, and antibodies in plants. PMID:16604461

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

2006-04-01

247

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-10-01

248

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

International Nuclear Information System (INIS)

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

249

PHYTOCHEMICAL AND ANTIOXIDANT CHARACTERIZATION OF FIREWEED (CRASSOCEPHALUM CREPIDIOIDES AND AFRICAN LETTUCE (LACTUCA TARAXACIFOLIA  

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Full Text Available Two neglected and under utilized green leaf vegetables (Fireweed and African lettuce in South-West, Nigeria was evaluated for phytochemical contents and antioxidant properties. The stems and leaves of the vegetables were cut, air-dried and ground to fine powder. The phytochemicals and antioxidants analyses were carried out using standard methods and the results obtained were analyzed statistically by ANOVA and DMRT analysis. The flavonoids, total phenol, oxalate, tannin and ascorbic acid contents were relatively higher in African lettuce than fireweed while total carotenoids, alkaloids and phytate were relatively higher in fireweed than African lettuce. It was only in total phenol content of both vegetables that there was no significant difference (P<0.05. There were no significant difference (P<0.05 in reducing power, Fe2+ chelating activity, DPPH and ABST+ radical scavenging activities of both vegetables, although these antioxidant properties were relatively higher in African lettuce than in fireweed. The two vegetables are highly rich in phytochemical antioxidant contents (although African lettuce is relatively richer and this will enhance their usefulness as medicinal plants as well as antioxidant agents in lipids and lipid containing foods.

J.O. ARAWANDE

2012-11-01

250

The Influence of Urea Modified Lignin from Palm Empty Bunch toward Vegetative Aspects of Lettuce Leaves  

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Full Text Available Modified of urea fertilizer with lignin’s palm empty bunch was applied to lettuce growth. This research aims to enhance the utility value of lignin from palm empty bunch, investigate slow release of urea-lignin fertilizer and vegetative aspect of leaves lettuce after period of week. Application of fertilizer was done in two difference places, namely green house laboratory and traditionally environment. Research showed that fertilized using urea fertilizer which modified by 2 % of lignin resulted amount (pc, length (cm and wide (cm of lettuce leave is better than fertilized only by urea in laboratory scale. Amount (pc, length (cm and wide (cm average of fresh lettuce leaves using urea modified by 2 % lignin resulted 8 pieces, 12 cm and 11 cm respectively on 6 weeks after plantation. Furthermore in traditionally environment, amount (pc, length (cm and wide average (cm of fresh lettuce leaves by using urea modified 3% lignin resulted 14 pieces, 25 cm and 21 cm consecutively on 6 weeks after plantation

Lucy Arianie

2013-12-01

251

Pesticide residue analysis in parsley, lettuce and spinach by LC-MS/MS.  

Science.gov (United States)

In this study, pesticide residues in parsley, lettuce and spinach (120 samples) were analyzed by the application of liquid chromatography-tandem mass spectrometry (LC-MS/MS). All samples of spinach, parsley or lettuce contained residues of three or more active substances. In parsley, carbendazim (100.0%), dichlorvos (100.0%), fenarimol (40.0%), pendimethalin (95.0%), in lettuce, diazinon (30.0%), dichlorvos (100.0%), pendimethalin (92.5%) phenthoate (12.5%), and in spinach, carbendazim (45.0%), cymoxanil (85.0%), dichlorvos (100.0%) and fenarimol (85.0%) were the significant active compounds. The maximum residue limits were exceeded in 28, 20 and 40 samples of parsley, lettuce and spinach, respectively. The results showed that there was a high occurrence of pesticide residues in parsley, lettuce and spinach samples from Hatay province, in which most of them were prohibited from use in Turkey for these vegetables. The contamination levels of these residues may be considered a serious public health problem according to the maximum residue limits (MRLs) of Turkey and the European Union (EU). PMID:24587520

Esturk, Okan; Yakar, Yasin; Ayhan, Zehra

2014-03-01

252

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

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Full Text Available Abstract Background Aquatic plants differ in their development from terrestrial plants in their morphology and physiology, but little is known about the molecular basis of the major phases of their life cycle. Interestingly, in place of seeds of terrestrial plants their dormant phase is represented by turions, which circumvents sexual reproduction. However, like seeds turions provide energy storage for starting the next growing season. Results To begin a characterization of the transition from the growth to the dormant phase we used abscisic acid (ABA, a plant hormone, to induce controlled turion formation in Spirodela polyrhiza and investigated their differentiation from fronds, representing their growth phase, into turions with respect to morphological, ultra-structural characteristics, and starch content. Turions were rich in anthocyanin pigmentation and had a density that submerged them to the bottom of liquid medium. Transmission electron microscopy (TEM of turions showed in comparison to fronds shrunken vacuoles, smaller intercellular space, and abundant starch granules surrounded by thylakoid membranes. Turions accumulated more than 60% starch in dry mass after two weeks of ABA treatment. To further understand the mechanism of the developmental switch from fronds to turions, we cloned and sequenced the genes of three large-subunit ADP-glucose pyrophosphorylases (APLs. All three putative protein and exon sequences were conserved, but the corresponding genomic sequences were extremely variable mainly due to the invasion of miniature inverted-repeat transposable elements (MITEs into introns. A molecular three-dimensional model of the SpAPLs was consistent with their regulatory mechanism in the interaction with the substrate (ATP and allosteric activator (3-PGA to permit conformational changes of its structure. Gene expression analysis revealed that each gene was associated with distinct temporal expression during turion formation. APL2 and APL3 were highly expressed in earlier stages of turion development, while APL1 expression was reduced throughout turion development. Conclusions These results suggest that the differential expression of APLs could be used to enhance energy flow from photosynthesis to storage of carbon in aquatic plants, making duckweeds a useful alternative biofuel feedstock.

Wang Wenqin

2012-01-01

253

Variations in bioactive substance contents and crop yields of lettuce (Lactuca sativa L.) cultivated in soils with different fertilization treatments.  

Science.gov (United States)

Changes in crop yields and bioactive substance contents were studied in lettuce crop concerning the influence of soil nutritional status as a result of compost and vermicompost additions obtained from different organic substrates. Plant productions and main pigment contents in lettuce were higher in all the fertilized soils than in the untreated soil, with the exception of the one treated with urban solid waste compost. These positive effects correlate with nitrogen level increase in soil. However, the high saline input of this compost prepared from food home wastes interferes in lettuce growth and prevents it from being higher than the control. Marked decreases in lettuce phenolic contents and antiradical activity were found in most of the treatments. Composts and vermicomposts produced through the processing of cattle manures, agro-industrial organic wastes significantly increased lettuce crop yield enriching its pigment contents, although, in some cases, antioxidant value and phenolic levels were reduced. PMID:19821565

Coria-Cayupán, Yanina Soledad; Sánchez de Pinto, María Ines; Nazareno, Mónica Azucena

2009-11-11

254

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

Science.gov (United States)

Development and activity of plant roots exhibit 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 10 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 grown as a model plant 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. PMID:24478764

Neumann, G; Bott, S; Ohler, M A; Mock, H-P; Lippmann, R; Grosch, R; Smalla, K

2014-01-01

255

Qualidade microbiológica e produtividade de alface sob adubação química e orgânica Microbiological quality and productivity of lettuce under chemical and organic fertilization  

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Full Text Available A contaminação de hortaliças por micro-oganismos patogênicos é uma realidade. Os adubos orgânicos têm sido responsabilizados por algumas contaminações de hortaliças observadas no Brasil. O objetivo deste trabalho foi avaliar a produtividade e a contaminação de alface por Salmonella sp. e coliformes a 45 °C, cultivada sob adubação orgânica. O delineamento experimental foi de blocos ao acaso, com seis tratamentos, em cinco repetições. Os tratamentos foram: T1 - Testemunha (sem adubação; T2 - Adubação química; T3 - Esterco de galinha; T4 - Esterco bovino; T5 - Húmus de minhoca; e T6 - Composto orgânico. As variáveis analisadas foram matéria fresca, matéria seca, macro e micronutrientes e contaminação microbiológica. Foi observada maior obtenção de matéria fresca nas parcelas adubadas com esterco de galinha (543 g, que diferiu estatisticamente da produção observada nos demais tratamentos. Não foi observada diferença estatística significativa entre tratamentos para matéria seca, com exceção da parcela com composto orgânico que apresentou o menor valor (3,7%. Não foi observada contaminação do solo e nem dos adubos orgânicos por esses micro-organismos. Porém, foi observada contaminação da água de irrigação e da alface por coliformes fecais. Existem fortes indícios de que a água de irrigação tenha sido o principal veículo de contaminação.Vegetable contamination with lethal microorganisms is a reality. Organic manure has been considered responsible for vegetable contamination in Brazil. The aim of this research was to evaluate the yield and lettuce contamination by Salmonella sp. and fecal coliforms, at 45 °C, grown under organic fertilization. The experimental design was in randomized blocks composed with 6 treatments in five replicates. The treatments were: T1 - Control (no fertilization; T2 - Chemical fertilization; T3 - Chicken manure; T4 - Cattle manure; T5 - Worm manure, and T6 - Organic compost. Fresh weight, dry matter percentage, macro and micronutrients, and microbiological contamination were recorded. The highest lettuce weight was observed in the parcels fertilized with chicken manure (543 g, which differed statistically from the weights observed in the other treatments. On the other hand, no statistical difference was observed in the dry matter percentage among the different treatments, with the exception of the value observed at the organic compost treatment, which was the lowest (3,7%. The soil and organic manure samples were not contaminated by Salmonella sp. and fecal coliforms. Nevertheless, irrigation water and lettuce samples were contaminated by fecal coliforms. There is strong evidence that irrigation water was the main source of lettuce contamination.

Ingergleice Machado de Oliveira Abreu

2010-05-01

256

Cooling and concentration of nutrient solution in hydroponic lettuce crop / Resfriamento e concentração da solução nutritiva em cultivo hidropônico da alface  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O trabalho foi realizado em ambiente protegido, no setor de Horticultura do Instituto Federal do Espírito Santo, Campus Itapina, Colatina, região Noroeste do Espírito Santo, com o objetivo de estudar e avaliar o efeito do resfriamento e da condutividade elétrica da solução nutritiva no crescimento d [...] a alface cv. Vitória de Santo Antão em cultivo hidropônico. O trabalho foi realizado em delineamento experimental inteiramente casualizado com dois fatores (controle de temperatura máxima da solução nutritiva: 26ºC e sem controle; e condutividade elétrica (EC) da solução: 1, 2 e 3 dS m-1 e quatro repetições. Cinquenta e dois dias após a semeadura foi realizada a colheita das plantas e avaliados a massas frescas e secas de folha, caule e raiz, volume de raízes, comprimento do caule e das raízes e porcentagem de água nas plantas. A temperatura da solução nutritiva influenciou o desempenho da alface em função do aumento da condutividade elétrica, demonstrando que o aumento da EC não compromete a produtividade quando há limitação na temperatura máxima da solução nutritiva, que nesse experimento foi de 26ºC. O resfriamento da solução proporcionou maior acúmulo de massa e porcentagem superior de água presente nas plantas, aumentando a produtividade da alface hidropônica em condições de clima tropical. Abstract in english The study was conducted in greenhouse at horticulture department of the Instituto Federal do Espírito Santo, Campus Itapina, Colatina, northwestern Espírito Santo state, Brazil, with the objective of evaluating the effect of cooling and electrical conductivity of nutrient solution on growth and deve [...] lopment of lettuce cv. Vitória de Santo Antão in hydroponics. The study was conducted in a completely randomized design with two factors (control of the maximum temperature of the nutrient solution: 26ºC and without control; and electrical conductivity, EC, of the solution: 1, 2 and 3 dS m-1) with three repetitions. The plants were harvested fifty-two days after sowing (DAS). We evaluated the dry and fresh mass of leaves, stems and roots, stem and root length, root volume and plant water content (%). The temperature of the nutrient solution influenced the behavior of lettuce influenced by the electrical conductivity, showing that the increase of the EC did not reduce the lettuce productivity when the maximum temperature of the nutrient solution is limited, which in this experiment was tested at 26ºC. The cooling of the nutrient solution provided greater accumulation of mass and a higher water percentage in plants, increasing the productivity of hydroponic lettuce in tropical climate.

Nilton N, Cometti; Diene M, Bremenkamp; Karla, Galon; Leonardo R, Hell; Marinaldo F, Zanotelli.

2013-06-01

257

Modeling uptake kinetics of cadmium by field-grown lettuce  

International Nuclear Information System (INIS)

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

258

Promotive Effects of Organic Solvents and Kinetin on Dark Germination of Lettuce Seeds 12  

Science.gov (United States)

Significant promotion in dark germination was observed when Grand Rapids lettuce (Lactuca sativa L.) seeds were soaked in acetone or dichloromethane, vacuum-dried, and imbibed at 25 C. Permeation of kinetin via these organic solvents further enhanced the dark germination. Those seeds that were affected by acetone and acetone-kinetin treatments and germinated in the dark escaped red-far red photocontrol of germination. Although abscisic acid was not detected in the organic solvent leachates, they did contain other inhibitory substances affecting lettuce seedling growth. In the light, acetone and acetone-kinetin treatments also enhanced the rate of germination and the increased germination by acetone-kinetin treatment was correlated with increased polyribosome formation. The possible mechanisms involved in promotion of lettuce seed germination by organic solvents and kinetin are discussed. PMID:16659500

Rao, V. Sivaji; Braun, Joseph W.; Khan, Anwar A.

1976-01-01

259

Invasive plant-derived biochar inhibits sulfamethazine uptake by lettuce in soil.  

Science.gov (United States)

Veterinary antibiotics are frequently detected in soils posing potential contamination of food crops. Sulfamethazine (SMT) uptake was investigated by lettuce (Lactuca sativa L.) grown in the soils treated with/without biochar derived from an invasive plant, burcucumber (Sicyos angulatus L.) (BBC700). Soils were contaminated with SMT at 5 and 50mgkg(-1), and treated with/without 5% BBC700 (ww(-1)). The lettuces were harvested after 5weeks of cultivation and were analyzed for SMT by a high performance liquid chromatography-tandem mass spectrometry after solid-phase extraction. With 5% BBC700, the uptake of SMT was reduced by 86% in the soil spiked with 5mgkg(-1) SMT compared to the control whereas a 63% reduction was observed in the soil spiked with 50mgkg(-1) SMT. Application of BBC700, into soils effectively reduced the SMT uptake by lettuce. PMID:24997958

Rajapaksha, Anushka Upamali; Vithanage, Meththika; Lim, Jung Eun; Ahmed, Mohamed Bedair M; Zhang, Ming; Lee, Sang Soo; Ok, Yong Sik

2014-09-01

260

Evaluation of total and thermotolerant coliforms on lettuce self service restaurants in Sinop-MT  

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Full Text Available Lettuce (Lactuca sativa L. is the leafy vegetable most consumed in the world and present high content of pro vitamin A in green leaves; it’s rich in calcium and iron and presents reasonable amounts of vitamins B1, B2, B6 and C. When eaten raw in salads they can to transmit pathogens if are inadequately cleaned. This study aimed to evaluate the microbiological quality of lettuce served in self-service restaurants in the city of Sinop – MT, concerning the total and thermotolerant coliforms. The laboratory analysis used was the Most Probable Number method (MPN. All samples were positive for total coliforms, reaching values above 1100 MPN/g, and when analyzed to confirm the presence of coliforms tolerant, all samples were negative. These results allowed observing that the values found for tolerant coliforms are within the standards established by legislation, but the total coliform count indicates poor hygiene lettuce served and consumed

P. C. Perondi

2013-11-01

 
 
 
 
261

Effects of nitrogen fertilizers on the growth and nitrate content of lettuce (Lactuca sativa L.).  

Science.gov (United States)

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

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

2014-04-01

262

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

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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.

Cheng-Wei Liu

2014-04-01

263

Changes in the metabolome of lettuce leaves due to exposure to mancozeb pesticide.  

Science.gov (United States)

This paper describes a proton high resolution magic angle spinning (HRMAS) nuclear magnetic resonance (NMR) metabolomic study of lettuce (Lactuca sativa L.) leaves to characterise metabolic adaptations during leaf growth and exposure to mancozeb. Metabolite variations were identified through multivariate analysis and checked through spectral integration. Lettuce growth was accompanied by activation of energetic metabolism, preferential glucose use and changes in amino acids, phospholipids, ascorbate, nucleotides and nicotinate/nicotinamide. Phenylalanine and polyphenolic variations suggested higher oxidative stress at later growth stages. Exposure to mancozeb induced changes in amino acids, fumarate and malate, suggesting Krebs cycle up-regulation. In tandem disturbances in sugar, phospholipid, nucleotide and nicotinate/nicotinamide metabolism were noted. Additional changes in phenylalanine, dehydroascorbate, tartrate and formate were consistent with a higher demand for anti-oxidant defence mechanisms. Overall, lettuce exposure to mancozeb was shown to have a significant impact on plant metabolism, with mature leaves tending to be more extensively affected than younger leaves. PMID:24518345

Pereira, Sara I; Figueiredo, Patricia I; Barros, António S; Dias, Maria C; Santos, Conceição; Duarte, Iola F; Gil, Ana M

2014-07-01

264

Effect of foliar calcium chloride treatment on the level of chlorogenic acid, ?-carotene, lutein and tocopherols in lettuce (Lactuca sativa L.  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of the presented study was to determine the effect of foliar application of CaCl2 on the level of ?-carotene, lutein, tocopherols and phenolic compounds in the leaves of lettuce cv. Omega (Lactuca sativa L.. The experiments were conducted in the greenhouse of the Faculty of Cultivation and Fertilisation of Horticultural Plants, University of Life Sciences in Lublin. During the growing period, 7 and 14 days before harvest, the plants were treated with a solution of CaCl2 with concentrations of 0.1 M and 0.2 M. Plants sprayed with water were the control treatment in the experiment. Analyses were performed on whole leaves and the blade without midrib. The obtained results indicate that the leaves of lettuce cv. Omega are a good source of phenolic compounds, carotenoids and tocopherols. The dominant carotenoid in lettuce cv. Omega was ?-carotene. Foliar application of CaCl2 on the plants did not have any significant effect on the level of ?-carotene and lutein in the whole leaves. The contents of tocopherols, total phenolic compounds and chlorogenic acid were dependent on the concentration of CaCl2. The application of 0.1 M CaCl2 solution in the plants resulted in a decrease in the level of total phenolic compounds and chlorogenic acid, and an increase in tocopherol content. However, the treatment of the plants with 0.2M CaCl2 solution caused a lowering of the concentration of tocopherols and an increase in the content of chlorogenic acid and total phenolic compounds.

Irena Perucka

2011-03-01

265

Impacts of major cations (K(+), Na (+), Ca (2+), Mg (2+)) and protons on toxicity predictions of nickel and cadmium to lettuce (Lactuca sativa L.) using exposure models.  

Science.gov (United States)

Biotic ligand models (BLM) explicitly accounting for hypothetical interactions with biotic ligands and bioavailability as dictated by water chemistry have been developed for various metals and different organisms. It is only recently that BLMs for plants have received increasing attention. Lettuce is one of the most important vegetable crops in the world. This study investigated the impacts of Ca(2+), Mg(2+), K(+), Na(+) and pH, on acute toxicity of Ni and Cd to butter-head lettuce seedlings (Lactuca sativa L.). 4-day assays with the root elongation inhibition (REI) as the endpoint were performed in hydroponic solutions. Magnesium was found to be the sole cation significantly enhancing the median inhibition concentration (IC50) of Ni(2+) with increasing concentration. By incorporating the competitive effects of Mg(2+), the Ni-toxicity prediction was improved significantly as compared to the total metal model (TMM) and the free ion activity model (FIAM). The conditional stability constants derived from the Ni-BLM were log K MgBL = 2.86, log K NiBL = 5.1, and f NiBL (50%)  = 0.57. A slight downtrend was observed in the 4-d IC50 of Cd(2+) at increasing H(+) concentrations, but this tendency was not consistent and statistically significant (p = 0.07) over the whole range. The overall variations of Cd-toxicity within the tested Na(+), K(+), Ca(2+) and Mg(2+) concentration ranges were relatively small and not statistically significant. 80 % of lettuce REI by Cd could be explained using both TMM and FIAM instead of BLM in the present study. Thus, the mechanistically underpinned models for soil quality guidelines should be developed on a metal-specific basis across different exposure conditions. PMID:24510448

Liu, Yang; Vijver, Martina G; Peijnenburg, Willie J G M

2014-04-01

266

Alelopatia de extratos de diferentes órgãos de mulungu na germinação de alface / Allelopathy of extracts of different organs of coral tree on the germination of lettuce  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O mulungu (Erythrina velutina) é uma árvore de crescimento rápido, com propriedades medicinais. O objetivo no presente trabalho foi avaliar o efeito alelopático do extrato aquoso de sementes, flores e cascas de mulungu na germinação e desenvolvimento de plântulas de alface cv. Mônica SF FI. O deline [...] amento experimental utilizado foi inteiramente casualizado com sete tratamentos [extrato de sementes a 100°C, extrato de sementes a 25°C, extrato de cascas a 100°C, extrato de cascas a 25°C, extrato de flores a 100°C, extrato de flores a 25°C e água destilada (testemunha)] com quatro repetições. Os extratos obtidos de sementes, independente da temperatura de extração reduziram a porcentagem e velocidade de germinação de sementes de alface e afetaram o desenvolvimento das plântulas. Os demais extratos não afetaram a germinação, mas causaram o aparecimento de plântulas anormais e mortas. Os extratos aquosos de sementes de mulungu têm potencial alelopático sobre as sementes de alface cv. Mônica SF FI. Abstract in english The coral tree (Erythrina velutina) is a fast growing tree with medicinal properties. The aim of this study was to evaluate the allelopathic effects of aqueous extract of seeds, flowers and bark of coral tree on seed germination and seedling development of lettuce cv. Mônica SF FI. The experimental [...] design was completely randomized with seven treatments [seed extract at 100°C, seed extract at 25°C, bark extract at 100°C, bark extract at 25°C, flower extract at 100°C, flower extract at 25°C and distilled water (control)] with four replications. The extracts of seeds, independent of the extraction temperature decreased the percentage and speed of germination of lettuce and affected the development of the seedlings. The other extracts did not affect germination, but caused the appearance of abnormal seedlings and dead. The aqueous extract of seeds of coral tree has allelopathic potential in the seeds of lettuce cv. Mônica SF FI.

Andreya K, Oliveira; Maria de Fatima B, Coelho; Sandra Sely S, Maia; Francisco EP, Diógenes; Sebastião, Medeiros Filho.

2012-09-01

267

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1998-09-01

268

[Identification of lettuce leaf nitrogen level based on adaboost and hyperspectrum].  

Science.gov (United States)

In order to facilitate lettuce fertilization in an economically rational way, an intelligent method to identify lettuce leaf nitrogen levels was studied. Lettuce samples of different nitrogen levels were cultivated in greenhouse with soilless cultivation method. In a particular growth period, the lettuce samples in various nitrogen levels were collected, then the FieldSpech3 spectrometer was used to acquire the hyperspectral data of the cultivated lettuce leaves. As there were much noise and redundant information in original hyperspectral data, standard normal variate transformation (SNV) was used to reduce the noise of the original hyperspectral data in this paper, then the principal component waves were extracted by principal component analysis (PCA). While K nearest neighbor (KNN) and support vector machine (SVM) were used for classification studies on the processed hyperspectra data respectively, adaptive boosting (Adaboost) was introduced into the two classifiers as it could improve the classification performance of weak classifiers, then Adaboost-KNN and Adaboost-SVM, the two integrated classification algorithms, were proposed. At last, the four classification algorithms were used for classification and identification of the same test sample data respectively, with the results showing that the classification accuracies of KNN, SVM, Adaboost-KNN and Adaboost-SVM were high up to 74.68%, 87.34%, 100% and 100%, among which the classification accuracies of Adaboost-KNN and Adaboost-SVM proposed in this paper were both good, and the stability of Adaboost-SVM was the best. Therefore, Adaboost-SVM used as a modeling method is suitable for the identification of lettuce leaf nitrogen level based on hyperspectrum, and it can also be used for reference to identify the nutrient elements of other crops in nondestructive testing methods. PMID:24611405

Sun, Jun; Jin, Xia-Ming; Mao, Han-Ping; Wu, Xiao-Hong; Tang, Kai; Zhang, Xiao-Dong

2013-12-01

269

Ocorrência generalizada do Lettuce mottle virus em três regiões produtoras de alface comercial do Estado de São Paulo / Occurrence of Lettuce mottle virus on three lettuce producing areas from São Paulo State  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Os sequivírus são vírus isométricos transmitidos por afídeos. Lettuce mottle virus (LeMoV), um provável sequivirus foi descrito no Brasil em 1982 e causa sintomas de mosaico semelhantes aos observados pelo Lettuce mosaic virus (LMV). Um levantamento para ocorrência do LeMoV nos campos de produção de [...] alface de três diferentes regiões do Estado de São Paulo (Mogi das Cruzes, Campinas e Bauru) foi realizado durante 2002 a 2005. RNA total foi extraído e utilizado na detecção, em RT-PCR, com oligonucleotídeos específicos para o LeMoV. Do total de 1362 amostras, 137 (10,05%) foram positivas para o LeMoV. Infecção mista com o LMV foi verificada em 43 amostras (31,4%). Foi verificada a ocorrência do LeMoV nas três diferentes regiões analisadas, porém sua ocorrência foi baixa nas diferentes épocas do ano. Abstract in english Sequiviruses are isometric aphid-borne plant viruses. Lettuce mottle virus (LeMoV), a putative sequivirus was first described in Brazil on 1982 causing similar mosaic symptoms as Lettuce mosaic virus (LMV). A survey for the occurrence of LeMoV on open field conditions was carried out during 2002 to [...] 2005 on Mogi das Cruzes, Campinas and Bauru in São Paulo state. Total RNA was extracted and used on RT-PCR with specific LeMoV primers. On 1362 samples tested, 137 (10,05%) were positive for LeMoV. Mixed infections with LMV was observed on 43 samples (31,4%). The presence of LeMoV was observed in the three different regions, but with low incidence during the year.

Renate, Krause-Sakate; Ana Carolina, Firmino; Adriana Salomão, Jadão; Marcelo A., Pavan; Norberto da, Silva; Sérgio Minoru, Hanai; Roberto Hiroto, Anbo; Thomas, Nietzsche.

270

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

Science.gov (United States)

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.

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

1990-01-01

271

Effect of 16 and 24 hours daily radiation (light) on lettuce growth  

Science.gov (United States)

A 50% increase in total radiation by extending the photoperiod from 16 to 24 hr doubled the weight of all cultivars of loose-leaf lettuce (Lactuca sativa L.) 'Grand Rapids Forcing', 'Waldmanns Green', 'Salad Bowl', and 'RubyConn', but not a Butterhead cultivar, 'Salina'. When total daily radiation (moles of photons) was the same, plants under continuous radiation weighed 30% to 50% more than plants under a 16 hr photoperiod. By using continuous radiation on loose-leaf lettuce, fewer lamp fixtures were required and yield was increased.

Koontz, H. V.; Prince, R. P.; Knott, W. M. (Principal Investigator)

1986-01-01

272

Índices morfofisiológicos e de produção de alface sob estresse salino / Morphophysiological indices and production of lettuce under saline stress  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese No Nordeste brasileiro, a alface é uma importante olerícola cultivada sob condições de irrigação em que são utilizadas águas de qualidade variada; uma das características da região é a variação espacial e temporal da qualidade dos recursos hídricos. Mesmo assim, são escassos os trabalhos referentes [...] aos efeitos da salinidade na formação de mudas e seu reflexo sobre a produção. Neste trabalho estudaram-se os efeitos de cinco níveis de condutividade elétrica da água de irrigação (CEa: 0,3, 1,0, 1,7, 2,4 e 3,1 dS m-1), em relação aos índices morfofisiológicos da alface 'Elba', a partir de mudas produzidas com águas de 0,3 e 3,1 dS m-1. Não houve efeito interativo entre os fatores estudados. O índice raiz/parte-aérea e a taxa de crescimento absoluto, foram afetados pela CEa, mas sem efeito sobre a taxa de crescimento relativo. O crescimento das plantas, cujas mudas foram produzidas com CEa de 3,1 dS m-1, foi inferior no início do ciclo, recuperando-se paulatinamente durante o crescimento; no momento da colheita, as taxas de crescimento absoluto e relativo foram, respectivamente, iguais e superiores às das plantas produzidas com água de baixa salinidade. A evapotranspiração diminuiu com o aumento da salinidade. As relações Na+/(Ca2++Mg2+) e Na+/K+ em folhas foram incrementadas linearmente com a salinidade, mas as plantas conseguiram manter o balanço iônico favorável. O rendimento da alface diminuiu 6,1 e 9,0% por aumento unitário de condutividade elétrica do extrato de saturação do solo e da água de irrigação, acima de 0,3 e 1,73 dS m-1, respectivamente. Abstract in english Lettuce is an important vegetable crop in the Northeast of Brazil cultivated under irrigated conditions using water of variable quality; one of the characteristics of this region is spatial and temporal variation in quality of water resources. In spite of this, research related to effects of salinit [...] y on the seedling formation and its posterior reflex on production is limited. In the present study, the effects of salinity of irrigation water (ECw: 0.3, 1.0, 1.7, 2.4 and 3.1 dS m-1) on growth response of lettuce 'Elba' using two types of seedlings produced with ECw of 0.3 and 3.1 dS m-1 were evaluated in a greenhouse. The studied factors had no interactive effect. Root/shoot ratio and absolute growth rate were affected by salinity although relative growth rate was not affected directly. The seedlings produced with ECw of 3.1 dS m-1 had lower growth rates at the beginning but recovered gradually during the growth cycle. In the last evaluation, the absolute and relative growth rates of these plants were, respectively, equal and superior to that of plants produced with water of low salinity. Increasing water salinity decreased evapotranspiration. The Na+/(Ca2++Mg2+) and Na+/K+ ratios in leaf increased linearly with the salinity but plants maintained favorable ionic balance. The decrease in lettuce yield was 6.1 and 9.0% per unit increase in electrical conductivity of the saturation extract of soil and of irrigation water above 0.3 and 1.73 dS m-1, respectively.

Sergio B. A., Viana; Pedro D., Fernandes; Hans R., Gheyi; Frederico A. L., Soares; Paulo T., Carneiro.

2004-04-01

273

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

International Nuclear Information System (INIS)

This thesis has explored the mechanisms of tritium 'absorption and incorporation in a human-consumed plant, lettuce (Lactuca sativa L.), due to atmospheric exposure. Foliar uptake appears to play a key role in absorption of tritium as tissue free water tritium. Whatever the development stage and the light conditions, the specific activity in tissue free water reaches that of water vapour in air in several hours. The specific activity ratio is then about 0, 4. The time to reach equilibrium in soil is over 24 hours in most cases: the specific activity ratio ranges then 0, 01 to 0, 26. Incorporation rate of tissue free water tritium as organically-bound tritium has been estimated to 0, 13 to 0, 16 % h-l in average over the growing period of the plant, but marked variations are observed during growth. In particular, a significant increase appeared at the exponential growth stage. Deposition and diffusion of tritium in soil lead to significant OBT activities in soil. Results globally indicate equilibrium between the different environmental compartments (air, soil, plant). However, some experiments have revealed high OBT concentrations regarding atmospheric level exposure and ask for a possible phenomenon of local tritium accumulation in OBT for particular conditions of exposure. (author)

274

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In this work, TiO2 photocatalysis was used to disinfect domestic wastewaters previously treated by different biological treatment systems: Upward-flow Anaerobic Sludge Blanket (UASB), facultative pond, and duckweed pond. The microorganisms monitored were E. coli, total coliforms, Shigella species, a [...] nd Salmonella species. Photocatalytic experiments were carried out using two light sources: a solar simulator (UV intensity: 68-70 W m-2) and black-light lamps (BLL UV intensity: 17-20 W m-2). Samples were taken after each treatment stage. Results indicate that bacterial photocatalytic inactivation is affected by characteristics of the effluent, including turbidity, concentration of organic matter, and bacterial concentration, which depend of the type of biological pretreatment previously used.

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

275

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

Directory of Open Access Journals (Sweden)

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.

Julián Andrés Rengifo-Herrera

2010-01-01

276

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english In this work, TiO2 photocatalysis was used to disinfect domestic wastewaters previously treated by different biological treatment systems: Upward-flow Anaerobic Sludge Blanket (UASB), facultative pond, and duckweed pond. The microorganisms monitored were E. coli, total coliforms, Shigella species, a [...] nd Salmonella species. Photocatalytic experiments were carried out using two light sources: a solar simulator (UV intensity: 68-70 W m-2) and black-light lamps (BLL UV intensity: 17-20 W m-2). Samples were taken after each treatment stage. Results indicate that bacterial photocatalytic inactivation is affected by characteristics of the effluent, including turbidity, concentration of organic matter, and bacterial concentration, which depend of the type of biological pretreatment previously used.

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

1636-16-01

277

Avaliação patogênica in vitro de Pythium middletonii Sparrow e Pythium dissotocum Drechsler em alface / In vitro pathogenic evaluation of Pythium middletonii Sparrow and Pythium dissotocum Drechsler in lettuce  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Infecções radiculares nos cultivos hidropônicos de alface são frequentes e, na maior parte das vezes, causadas por espécies de Pythium, extremamente bem adaptadas ao ambiente aquático. Este estudo buscou avaliar o potencial patogênico in vitro de Pythium middletonii e P. dissotocum, em quatro cultiv [...] ares de alface: Elisa (lisa), Vera (crespa), Mimosa (mimosa) e Tainá (americana). Sementes de alface, de cada cultivar, foram desinfetadas superficialmente, pré-germinadas por 24 horas, e colocadas na superfície do meio ágar-água. Em seguida, um disco de micélio dos isolados de Pythium, foi disposto no centro de cada placa. Placas contendo apenas as sementes de alface serviram como controle. O delineamento experimental utilizado foi inteiramente casualizado, com cinco repetições, sendo cada uma delas representada por uma placa de Petri. Avaliou-se o comprimento dos hipocótilos, das radículas e a porcentagem das plântulas sobreviventes após dez dias de incubação. O experimento foi conduzido na temperatura ideal de crescimento da alface (20ºC), e nas ideais para o crescimento dos isolados, 23ºC para P. middletonii e 27ºC para P. dissotocum. A 20ºC, P. dissotocum foi mais patogênico que P. middletonii, reduzindo significativamente o comprimento dos hipocótilos e, principalmente, das radículas, de praticamente todas as cultivares. Na temperatura de 27ºC, P. dissotocum foi responsável pela mais baixa porcentagem de plântulas sobreviventes entre as cultivares, sendo mais patogênico em Vera (54% de sobrevivência). Dentre as cultivares analisadas, a Mimosa mostrou tendência de menor suscetibilidade a este patógeno, apresentando a maior porcentagem de plântulas sobreviventes e o maior comprimento das radículas em relação ao controle. P. dissotocum apresentou maior crescimento micelial e foi mais patogênico que P. middletonii em todos os experimentos realizados. Abstract in english Root infections in hydroponic lettuce are frequent and mostly caused by Pythium species, which are extremely well adapted to aquatic environments. The present study aimed to evaluate in vitro the pathogenic potential of Pythium middletonii and Pythium dissotocum in four cultivars of lettuce, Elisa ( [...] smooth), Vera (curly), Mimosa (mimosa) and Tainá (American). Lettuce seeds from each cultivar were superficially disinfected, pre-germinated for 24 hours and placed on the water agar medium surface. Then, a dish containing mycelium from Pythium isolates was placed in the center of each plate. Control consisted of plates containing lettuce seeds only. Experimental design was completely randomized, with five replicates, each one represented by a Petri dish. Hypocotyl and radical length besides surviving seedlings percentage after ten days of incubation were evaluated. The experiment was carried out, at different temperatures, and the pathogenicity of the isolates was investigated at the ideal temperature for the lettuce (20ºC), and at the ideal temperatures for the growth of the isolates, 23ºC for P. middletonii and 27ºC for P. dissotocum. At 20ºC, P. dissotocum had higher pathogenicity on lettuce cultivars than P. middletonii, significantly decreasing the length of hypocotyls, especially radicles, of most cultivars. For P. dissotocum, 27ºC was the most suitable temperature for the specimen growth; however, it led to the lowest percentage of surviving seedlings among all cultivars, with the lowest percentage (54%) detected for Vera. Among the cultivars, Mimosa presented higher percentage of survivor seedlings and higher length of radicles in relation to the control, and thus was considered less susceptible to the pathogen. P. dissotocum presented higher mycelium growth and was more pathogenic than P. middletonii in all experiments.

F.R., Baptista; C.L.A, Pires-Zottarelli; L.D., Teixeira; N.A., Santos Júnior.

2011-03-01

278

Avaliação patogênica in vitro de Pythium middletonii Sparrow e Pythium dissotocum Drechsler em alface / In vitro pathogenic evaluation of Pythium middletonii Sparrow and Pythium dissotocum Drechsler in lettuce  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Infecções radiculares nos cultivos hidropônicos de alface são frequentes e, na maior parte das vezes, causadas por espécies de Pythium, extremamente bem adaptadas ao ambiente aquático. Este estudo buscou avaliar o potencial patogênico in vitro de Pythium middletonii e P. dissotocum, em quatro cultiv [...] ares de alface: Elisa (lisa), Vera (crespa), Mimosa (mimosa) e Tainá (americana). Sementes de alface, de cada cultivar, foram desinfetadas superficialmente, pré-germinadas por 24 horas, e colocadas na superfície do meio ágar-água. Em seguida, um disco de micélio dos isolados de Pythium, foi disposto no centro de cada placa. Placas contendo apenas as sementes de alface serviram como controle. O delineamento experimental utilizado foi inteiramente casualizado, com cinco repetições, sendo cada uma delas representada por uma placa de Petri. Avaliou-se o comprimento dos hipocótilos, das radículas e a porcentagem das plântulas sobreviventes após dez dias de incubação. O experimento foi conduzido na temperatura ideal de crescimento da alface (20ºC), e nas ideais para o crescimento dos isolados, 23ºC para P. middletonii e 27ºC para P. dissotocum. A 20ºC, P. dissotocum foi mais patogênico que P. middletonii, reduzindo significativamente o comprimento dos hipocótilos e, principalmente, das radículas, de praticamente todas as cultivares. Na temperatura de 27ºC, P. dissotocum foi responsável pela mais baixa porcentagem de plântulas sobreviventes entre as cultivares, sendo mais patogênico em Vera (54% de sobrevivência). Dentre as cultivares analisadas, a Mimosa mostrou tendência de menor suscetibilidade a este patógeno, apresentando a maior porcentagem de plântulas sobreviventes e o maior comprimento das radículas em relação ao controle. P. dissotocum apresentou maior crescimento micelial e foi mais patogênico que P. middletonii em todos os experimentos realizados. Abstract in english Root infections in hydroponic lettuce are frequent and mostly caused by Pythium species, which are extremely well adapted to aquatic environments. The present study aimed to evaluate in vitro the pathogenic potential of Pythium middletonii and Pythium dissotocum in four cultivars of lettuce, Elisa ( [...] smooth), Vera (curly), Mimosa (mimosa) and Tainá (American). Lettuce seeds from each cultivar were superficially disinfected, pre-germinated for 24 hours and placed on the water agar medium surface. Then, a dish containing mycelium from Pythium isolates was placed in the center of each plate. Control consisted of plates containing lettuce seeds only. Experimental design was completely randomized, with five replicates, each one represented by a Petri dish. Hypocotyl and radical length besides surviving seedlings percentage after ten days of incubation were evaluated. The experiment was carried out, at different temperatures, and the pathogenicity of the isolates was investigated at the ideal temperature for the lettuce (20ºC), and at the ideal temperatures for the growth of the isolates, 23ºC for P. middletonii and 27ºC for P. dissotocum. At 20ºC, P. dissotocum had higher pathogenicity on lettuce cultivars than P. middletonii, significantly decreasing the length of hypocotyls, especially radicles, of most cultivars. For P. dissotocum, 27ºC was the most suitable temperature for the specimen growth; however, it led to the lowest percentage of surviving seedlings among all cultivars, with the lowest percentage (54%) detected for Vera. Among the cultivars, Mimosa presented higher percentage of survivor seedlings and higher length of radicles in relation to the control, and thus was considered less susceptible to the pathogen. P. dissotocum presented higher mycelium growth and was more pathogenic than P. middletonii in all experiments.

F.R., Baptista; C.L.A, Pires-Zottarelli; L.D., Teixeira; N.A., Santos Júnior.

279

Efeitos na fotossíntese e área foliar de cultivares de alface inoculadas mecanicamente com patótipos do Lettuce mosaic virus e Lettuce mottle virus / Effects on photosynthesis and foliar area of lettuce cultivar mechanically inoculated with Lettuce mosaic virus pathotypes and Lettuce mottle virus  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Levantamentos realizados no estado de São Paulo indicaram a ocorrência isolada e em infecções mistas do Lettuce mosaic virus (LMV) e do Lettuce mottle virus (LeMoV) em plantas de alface (Lactuca sativa). O presente trabalho teve como objetivo estudar os efeitos da infecção isolada e mista entre o LM [...] V (patótipos II e IV) e o LeMoV, em cultivares de alface suscetível (White Boston) e tolerante (Elisa - gene mol¹) ao LMV patótipo II. As plantas foram inoculadas via extrato vegetal tamponado com isolados de LMV-II, LMV-IV e LeMoV separadamente e em diferentes combinações, com intervalo de 24 h ou simultaneamente com os dois vírus. As plantas infetadas foram analisadas utilizando-se hospedeiras diferenciais para o LMV e o LeMoV, e no caso do LMV pelo teste sorológico de PTA-ELISA. Nas avaliações de peso fresco e seco, área foliar e teor de clorofila, observou-se que a cultivar White Boston foi a mais afetada por ambos os vírus. As infecções mistas e isoladas na cultivar Elisa causaram efeitos semelhantes, provavelmente devido a presença do gene mo1¹ de tolerância ao LMV-II. O isolado LMV-IV foi considerado o mais agressivo nestas cultivares quando comparado ao LMV-II e o LeMoV. Abstract in english A survey of virus isolates causing mosaic in lettuce (Lactuca sativa) in the state of São Paulo, Brazil, indicated the occurrence of Lettuce mosaic virus (LMV) and Lettuce mottle virus (LeMoV) alone or in mixed infections. The objective of this work was to study the effects of single and mixed infec [...] tions between LMV (pathotypes II and IV) and LeMoV in susceptible (White Boston) and tolerant (Elisa, mo1¹ gene) lettuce cultivars. Plants were sap-inoculated with LMV-II, LMV-IV and LeMoV, in single infections and in different combinations, with either a 24 h interval between the two viruses or simultaneously. Plants were tested for the presence of LMV and LeMoV using differential hosts and, in the case of LMV, the serological test (PTA-ELISA) was used. In the evaluations of fresh and dry weight, leaf area and chlorophyll content, the White Boston cultivar was observed to be the most affected by both viruses. This cultivar's response to single and mixed infections was similar, probably due to the presence of the mo1¹ gene which confers tolerance to LMV-II. When compared to LMV-IV and LeMoV, LMV-IV was the most aggressive isolate.

Adriana S, Jadão; Marcelo A, Pavan; Renate, Krause-Sakate; F. Murilo, Zerbini.

280

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

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Full Text Available The minimal processing of horticultural products endears the raw material and is convenient to the consumer due to the facility for preparing and consuming. The objective of this work was to develop an active packaging for fresh-cut iceberg lettuce (Lactuca sativa L. to increase its shelf life. Minimally processing methodology was defined and the product quality was determined by sensorial, physico-chemical and microbiological analysis. The lettuce tree was selected, trimmed, pre-washed, soaked in sanitized water (100ppm of active chlorine for 15 minutes and centrifuged. The lettuce leafs were packed in polypropylene pots with a sachet containing 1-methylcyclopropene (1-MCP and sealed with biodegradable starch film. Soon after the processing, the product was stored at 4oC for 12 days. Periodically samples were evaluated in terms of appearance and purchase intention, soluble solids and vitamin C contents, pH, texture, color, weight loss and total count of mesophilic and psicotrofic microorganisms, lactic bacteria, mould and yeast. Using 1-MCP in sachet format did not increase the lettuce shelf life but the minimal processing combined with packaging sealed with biodegradable film is practicable as the product showed good sensorial acceptance, low microbiological counts and shelf life of 5 days at 4oC.O processamento mínimo de produtos hortícolas agrega valor à matéria-prima e são convenientes ao consumidor, devido à facilidade de preparo e consumo. O objetivo do trabalho foi desenvolver uma embalagem ativa para alface americana (Lactuca sativa L. minimamente processada visando o aumento da vida útil. Foi definida uma metodologia de processamento mínimo e a qualidade do produto foi acompanhada através de avaliação sensorial, físico-química e microbiológica. As cabeças de alface foram desfolhadas, selecionadas, pré-lavadas, sanificadas (100 ppm de cloro ativo por 15 minutos e centrifugadas. As folhas foram acondicionadas em potes de polipropileno contendo sachês com 1-metilciclopropeno (1-MCP e seladas com filme biodegradável de amido. Logo após o processamento, o produto foi armazenado a 4ºC por 12 dias. Periodicamente amostras foram avaliadas sensorialmente (aparência e intenção de compra e foram determinados os teores de sólidos solúveis e vitamina C, pH, textura, cor, perda de massa e contagem total de microrganismos mesófilos, psicrotróficos, bactérias láticas, bolores e leveduras. O uso de 1-MCP na forma de sachê não aumentou a vida útil da alface em relação ao controle, mas o processamento mínimo associado à embalagem selada com filme biodegradável é uma técnica viável, pois o produto apresentou boa aceitação sensorial, contaminação microbiológica baixa e vida de prateleira de 5 dias a 4oC.

Fábio Yamashita

2010-09-01

 
 
 
 
281

Avaliação da reação de genótipos de alface (Lactuca sativa L.) ao Lettuce mosaic virus (LMV) / Reaction of Lactuca sativa L. lines to Lettuce mosaic virus (LMV)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O trabalho teve como meta avaliar a reação de 18 linhagens superiores do programa de melhoramento de alface (Lactuca sativa L.) do IAC e de seis cultivares comerciais, ao Lettuce mosaic virus (LMV). Em condições de campo, na região de Atibaia (SP), foram observados sintomas de mosaico, nanismo e nec [...] rose em plantas das cultivares Rider, 'Karla H25' e Hortência. O vírus presente nos isolados foi identificado por meio de inoculação mecânica em plantas indicadoras e diferenciadoras e de testes sorológicos de Plate Trapped Antigen-Enzyme linked-immunosorbent assay (PTA-ELISA). Nas amostras avaliadas, identificou-se a espécie LMV pelo PTA-ELISA e do patotipo IV pela reação nas hospedeiras diferenciais. Para a avaliação do comportamento dos genótipos de alface, foi empregado o LMV isolado 'Karla H25'. Foram submetidos à inoculação 24 genótipos de alface empregando-se, como controle positivo, a alface 'White Boston' por sua suscetibilidade ao LMV. O delineamento experimental foi inteiramente ao acaso e analisado pelo teste do qui-quadrado. Detectaram-se genótipos com comportamento de suscetibilidade e de tolerância. Nos genótipos 3 e 4, foram observadas plantas com comportamento de tolerância ao LMV isolado 'Karla H25', enquanto nos demais genótipos, constataram-se plantas com comportamento suscetível. O plantio de cultivares tolerantes pode ser uma alternativa aos prejuízos causados pela infecção pelo LMV com conseqüente diminuição do uso de produtos químicos para o controle dos afídeos vetores. Abstract in english Reactions to one isolate from diseased lettuce plants collected in 2003 in Atibaia, SP, were studied in six varieties and 18 selected lettuce (Lactuca sativa L.) lines. Underdeveloped, malformed leaves with mosaic symptoms and also necrotic leaves were found under field conditions in Raider, 'Karla [...] H25' and Hortência lettuce cultivars. These symptomatic plants were sampled and the virus etiology studied by PTA-ELISA and by means of mechanical inoculation on test plants and on differential lettuce cultivars resistant to Lettuce mosaic virus, LMV pathotypes I, II and III. LMV pathotype IV was identified in all cultivars studied by the reaction in the differential hosts. 'Karla H25'isolate was selected to screen the best lines of the breeding as well as lettuce program and commercial varieties. Twenty-four best lines of the program were inoculated with this isolate and the evaluations were based on symptoms. Symptomless lettuce plants were additionally tested for LMV presence, in PTA-ELISA, and by retro-inoculation to Chenopodium amaranticolor. The results indicated lines with varied degrees of susceptibility and tolerance. Lines 3 and 4 showed tolerance and this suggests that they can provide a good alternative for disease control and also that they might contribute in the reduction of chemical control.

Rosa Maria, Chung; Joaquim Adelino de, Azevedo Filho; Addolorata, Colariccio.

282

Avaliação da reação de genótipos de alface (Lactuca sativa L. ao Lettuce mosaic virus (LMV Reaction of Lactuca sativa L. lines to Lettuce mosaic virus (LMV  

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Full Text Available O trabalho teve como meta avaliar a reação de 18 linhagens superiores do programa de melhoramento de alface (Lactuca sativa L. do IAC e de seis cultivares comerciais, ao Lettuce mosaic virus (LMV. Em condições de campo, na região de Atibaia (SP, foram observados sintomas de mosaico, nanismo e necrose em plantas das cultivares Rider, 'Karla H25' e Hortência. O vírus presente nos isolados foi identificado por meio de inoculação mecânica em plantas indicadoras e diferenciadoras e de testes sorológicos de Plate Trapped Antigen-Enzyme linked-immunosorbent assay (PTA-ELISA. Nas amostras avaliadas, identificou-se a espécie LMV pelo PTA-ELISA e do patotipo IV pela reação nas hospedeiras diferenciais. Para a avaliação do comportamento dos genótipos de alface, foi empregado o LMV isolado 'Karla H25'. Foram submetidos à inoculação 24 genótipos de alface empregando-se, como controle positivo, a alface 'White Boston' por sua suscetibilidade ao LMV. O delineamento experimental foi inteiramente ao acaso e analisado pelo teste do qui-quadrado. Detectaram-se genótipos com comportamento de suscetibilidade e de tolerância. Nos genótipos 3 e 4, foram observadas plantas com comportamento de tolerância ao LMV isolado 'Karla H25', enquanto nos demais genótipos, constataram-se plantas com comportamento suscetível. O plantio de cultivares tolerantes pode ser uma alternativa aos prejuízos causados pela infecção pelo LMV com conseqüente diminuição do uso de produtos químicos para o controle dos afídeos vetores.Reactions to one isolate from diseased lettuce plants collected in 2003 in Atibaia, SP, were studied in six varieties and 18 selected lettuce (Lactuca sativa L. lines. Underdeveloped, malformed leaves with mosaic symptoms and also necrotic leaves were found under field conditions in Raider, 'Karla H25' and Hortência lettuce cultivars. These symptomatic plants were sampled and the virus etiology studied by PTA-ELISA and by means of mechanical inoculation on test plants and on differential lettuce cultivars resistant to Lettuce mosaic virus, LMV pathotypes I, II and III. LMV pathotype IV was identified in all cultivars studied by the reaction in the differential hosts. 'Karla H25'isolate was selected to screen the best lines of the breeding as well as lettuce program and commercial varieties. Twenty-four best lines of the program were inoculated with this isolate and the evaluations were based on symptoms. Symptomless lettuce plants were additionally tested for LMV presence, in PTA-ELISA, and by retro-inoculation to Chenopodium amaranticolor. The results indicated lines with varied degrees of susceptibility and tolerance. Lines 3 and 4 showed tolerance and this suggests that they can provide a good alternative for disease control and also that they might contribute in the reduction of chemical control.

Rosa Maria Chung

2007-01-01

283

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 i [...] rrigação: 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. Abstract in english 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 comparison to AF1743.

George RL, Bandeira; Helder C dos S, Pinto; Paula S, Magalhães; Carlos A, Aragão; Sérgio OP de, Queiroz; Essione R, Souza; Sirando L, Seido.

2011-06-01

284

Inhibition of root growth by narciclasine is caused by DNA damage-induced cell cycle arrest in lettuce seedlings.  

Science.gov (United States)

Narciclasine (NCS) is an Amaryllidaceae alkaloid isolated from Narcissus tazetta bulbs. Its phytotoxic effects on plant growth were examined in lettuce (Lactuca sativa L.) seedlings. Results showed that high concentrations (0.5-5 ?M) of NCS restricted the growth of lettuce roots in a dose-dependent manner. In NCS-treated lettuce seedlings, the following changes were detected: reduction of mitotic cells and cell elongation in the mature region, inhibition of proliferation of meristematic cells, and cell cycle. Moreover, comet assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay indicated that higher levels NCS (0.5-5 ?M) induced DNA damage in root cells of lettuce. The decrease in meristematic cells and increase in DNA damage signals in lettuce roots in responses to NCS are in a dose-dependent manner. NCS-induced reactive oxygen species accumulation may explain an increase in DNA damage in lettuce roots. Thus, the restraint of root growth is due to cell cycle arrest which is caused by NCS-induced DNA damage. In addition, it was also found that NCS (0.5-5 ?M) inhibited the root hair development of lettuce seedlings. Further investigations on the underlying mechanism revealed that both auxin and ethylene signaling pathways are involved in the response of root hairs to NCS. PMID:24482192

Hu, Yanfeng; Li, Jiaolong; Yang, Lijing; Nan, Wenbin; Cao, Xiaoping; Bi, Yurong

2014-09-01

285

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  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese 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 sali [...] no (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. Abstract in english 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 wastew [...] ater 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 Floating conditions. The single use of deep well water and reject brine decreased 22.7 and 39.6% the lettuce yield, respectively. For a better combination of fresh and brackish waters, the use of brackish water to replace ETc loss may increase the lettuce yield in comparison to use these waters to prepare the NS; this result was registered for deep well water and reject.

Alexandre Nascimento dos, Santos; Ênio Farias de França e, Silva; Tales Miler, Soares; Raquele Mendes Lira, Dantas; Manassés Mesquita da, Silva.

2011-06-01

286

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  

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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 Floating conditions. The single use of deep well water and reject brine decreased 22.7 and 39.6% the lettuce yield, respectively. For a better combination of fresh and brackish waters, the use of brackish water to replace ETc loss may increase the lettuce yield in comparison to use these waters to prepare the NS; this result was registered for deep well water and reject.

Alexandre Nascimento dos Santos

2011-06-01

287

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

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The role of lytic bacteriophages in preventing cross contamination of produce has not been evaluated. A cocktail of three lytic phages specific for E. coli O157:H7 (EcoShield™) or a control (phosphate buffered saline, PBS) was applied to lettuce by either; (1) immersion of lettuce in 500 ml of EcoShield™ 8.3 log PFU/ml or 9.8 log PFU/ml for up to 2 min before inoculation with E. coli O157:H7; (2) spray-application of EcoShield™ (9.3 log PFU/ml) to lettuce after inoculation with E. coli ...

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

2013-01-01

288

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

International Nuclear Information System (INIS)

to 3.14 day. SEM and TEM observations showed that cells irradiated at 1.5 and 3 kGy showed disrupted cell membrane. These results indicate that gamma irradiation could be a useful decontamination technology to improve food safety of lettuce by destroying cells of S. Typhimurium and S. aureus. - Highlights: ? Low dose of gamma irradiation destroyed cell envelope of the pathogens. ? Gamma irradiation decreased cell counts of the pathogens on lettuce. ? Gamma irradiation could be useful in improving food safety of lettuce.

289

Survey of vesicular-arbuscular mycorrhizae in lettuce production in relation to management and soil factors  

Science.gov (United States)

The occurrence of vesicular-arbuscular mycorrhizae (VAM) root colonization and spore number in soil was assessed for 18 fields under intensive lettuce (Lactuca sativa L.) production in California during July and August of 1995. Data on management practices and soil characteristics were compiled for each field, and included a wide range of conditions. The relationship between these factors and the occurrence of VAM in these fields was explored with multivariate statistical analysis. VAM colonization of lettuce tended to decrease with the use of chemical inputs, such as pesticides and high amounts of P and N fertilizers. Addition of soil organic matter amendments, the occurrence of other host crops in the rotation, and soil carbon:phosphorus and carbon:nitrogen ratios, were positively associated with VAM colonization of lettuce roots. The number of VAM spores in soil was strongly correlated with the number of other host crops in the rotation, the occurrence of weed hosts and sampling date, but was more affected by general soil conditions than by management inputs. Higher total soil N, C and P, as well as CEC, were inversely related to soil spore number. A glasshouse study of the two primary lettuce types sampled in the field showed no significant differences in the extent of root colonization under similar growing conditions. The results of this study are compared with other studies on the effects of management and soil conditions on mycorrhizal occurrence in agriculture.

Miller, R. L.; Jackson, L. E.

1998-01-01

290

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

International Nuclear Information System (INIS)

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

291

A STUDY ON THE ACCUMULATION OF PERCHLORATE IN YOUNG HEAD LETTUCE  

Science.gov (United States)

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

292

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

Science.gov (United States)

Broccoli (Brassica oleracea L. var. italica) and lettuce (Lactuca sativa L.) were grown on Willamette sil (Pachic Ultic Argixerolls) amended 1 and 2 yr earlier with chrome tannery wastes at rates up to 192 Mg ha to determine nutrient and trace element availability. Soils were sam...

293

Phosphorus levels in soil and lettuce production due to phosphorus fertilization  

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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.

José Ricardo Mantovani

2014-09-01

294

Economic analysis of cucumber and lettuce intercropping under greenhouse in the winter-spring.  

Science.gov (United States)

The economical analysis complements the evaluation of the intercrop systems efficiency, considering besides the physical production of crops, the price of products according to their quality classification and time of the year. Intercropping systems of lettuce and cucumber in two plant populations under greenhouse were economically evaluated in winter-spring, in Jaboticabal City, São Paulo State, Brazil. The total operating cost (TOC) of cucumber and lettuce as sole crop and intercropping were estimated, as well as gross revenue (GR) and operating profit (OP). The labor for the crops was the component with greater participation in the TOC of crops in intercropping and single crop. Greater GR and OP were observed in intercrops established by transplanting lettuce and cucumbers on the same day. Considering the operating profit and the land efficient ratio, it is recommended the intercropping of lettuce transplanted until 10 days after the transplanting (DAT) of cucumber with two rows per plot, and at 0 DAT of cucumber grown with a row plot. PMID:21670889

Rezende, Bráulio L A; Cecílio Filho, Arthur B; Barros Júnior, Aurélio P; Porto, Diego R Q; Martins, Maria Inez E G

2011-06-01

295

Evaluation of Heavy Metals from Soil and Lettuce Grown in Irrigated Farmlands of Kaduna Metropolis Nigeria  

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Full Text Available The aim of this research study is to determine the level of heavy metal such as cadmium, copper and lead were investigated in soil and lettuce grown in irrigated farmlands of Kaduna metropolis so as to ascertain the extent of pollution. Concentrations of heavy metals were determined using atomic absorption spectrophotometer. The results obtained were compared with limit recommended by FAO/WHO (2007 Allimentarius standard so as to ascertain the extent of their pollution. The level of cadmium in lettuce ranged from 0.03-1.37 ?g/g. The concentrations of lead was found to be in range of 0.96-3.81 ?g/g, were above the limit stipulated by WHO while copper concentration ranged from 0.27-4.97 ?g/g were within the recommended limit given by the FAO/WHO (2007 standard. This suggests that the lettuce grown in the studied areas were prone to lead and cadmium toxicity as at the time of this research work. Pearson correlation shows positive correlation between soil and vegetable (lettuce in these irrigation sites.

W.L.O. Jimoh

2012-03-01

296

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

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Full Text Available Hydroponically-grown produce may be a way of helping to feed the world a variety of fruits and vegetables, regardless of soil quality, space availability or climate. The objective of this study was to determine whether hydroponicallygrown lettuce contains as much ascorbic acid and tocopherol as soil-grown lettuce. We analyzed four varieties of lettuce, including: Waldmann’s Dark Green, Red Lollo Antago, Red Romaine Annapolis, and Butterleaf. The tocopherol content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 229%, 497% and 492% higher, respectively, compared to their soil-grown counterpart. The ascorbic acid content of hydroponically-grown Waldmann’s Dark Green, Red Lollo Antago, and Red Romaine Annapolis was 93%, 171% and 216% higher, respectively, compared to their soil-grown counterparts. Hydroponically grown lettuce varieties are significantly higher in both ascorbic acid and tocopherol content than their soil-grown counterparts, and hydroponic gardening is a viable option for producing nutritious fruits and vegetables.

Drew N. Buchanan

2013-09-01

297

UPTAKE OF CADMIUM FROM PHOSPHATE FERTILIZERS BY PEAS, RADISHES, AND LETTUCE  

Science.gov (United States)

Cadium uptake from phosphate fertilizers by radish (Raphanus sativa) lettuce (Latuca sativa) and garden peas (Pisum satium) was investigated in the greenhouse. Fertilizer in all treatments was applied at the rate of 100 P/g soil to pots containing 4kg soil. When reagent grade mon...

298

COMPARATIVE TOXICITY OF SIX TEST CHEMICALS TO LETTUCE USING TWO ROOT ELONGATION TEST METHODS (JOURNAL VERSION)  

Science.gov (United States)

Lettuce (Lactuca sativa L., cv buttercrunch) was used to evaluate and compare the results from two different root elongation phytotoxicity test methods with the same six test substances. Seeds were either germinated in the dark on an inclined filter paper substrate with one end i...

299

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  

Science.gov (United States)

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.

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

300

Germination and vigor of lettuce seeds (Lactuca sativa L. pelleted with homeopathic preparations Alumina and Calcarea carbonica subjected to toxic levels of aluminum.  

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Full Text Available Background: aluminum toxicity is the most important factor limiting the growth of plants in acid soils, whereas current treatments are unfeasible. For this reason, alternatives are sought for, among which homeopathic treatment. Aims: this study aimed at evaluating the influence of homeopathic preparations Alumina 6cH, Alumina 12cH, Calcarea carbonica 6cH and Calcarea carbonica 12cH on the germination and vigor of lettuce seeds subjected to toxic levels of aluminum in paper-solution. At the same time, it was sought to develop a new procedure to apply homeopathic preparations in plants (pelleting. Methods: the statistical design was entirely randomized (CRD with 6 treatments and 4 repetitions. Treatments included: 1 pelleted seeds/talc + Alum 6 cH; 2 pelleted seeds/talc + Alum 12cH; 3 pelleted seed/talc + Calc 6cH; 4 pelleted seeds/talc + Calc 12cH; 5 pelleted seeds/talc + distilled water; 6 non pelleted seeds (control. Variables evaluated were: germination percentage (GP, germination speed index (GSI and radicle length (RL. Results: there was significant difference in GSI and RL – variables that reflect the vigor of seeds - between the samples treated with homeopathic preparations and the controls Conclusions: homeopathic preparations Alumina 6cH and 12cH and Calcarea carbonica 6cH and 12cH had significant effect on the vigor of lettuce seeds subjected to stress conditions.

Vicente Wagner Dias Casali

2010-12-01

 
 
 
 
301

Frequência de Lettuce big-vein associated virus e Mirafiori lettuce big-vein virus em Plantas de alface no Estado de São Paulo e transmissão através de extrato vegetal e solo / Frequency of Lettuce big-vein associated virus and Mirafiori lettuce big-vein virus in symptomatic and assymptomatic lettuce plants and sap and soil transmission  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A presença de sintomas de 'big vein' ou engrossamento das nervuras em alface e a associação do Lettuce big-vein associated virus (LBVaV) e Mirafiori lettuce big-vein virus (MLBVV) foram verificadas por RT-PCR utilizando-se oligonucleotídeos específicos para ambos os vírus. Foram coletadas 366 planta [...] s sintomáticas nas regiões de Bauru, Campinas e Mogi das Cruzes no estado de São Paulo nos meses de junho e setembro de 2004 e abril e julho de 2005, e 18 plantas assintomáticas na região de Mogi das Cruzes no mês de dezembro de 2004. Infecção mista do LBVaV e MLBVV foi detectada em 76,2% das plantas sintomáticas, em 11,5% somente o MLBVV foi detectado e em 6,6% somente o LBVaV. Nas plantas assintomáticas coletadas em dezembro na região de Mogi das Cruzes, em áreas de alta incidência da doença durante o inverno, foi detectada a presença de MLBVV em 9 amostras e LBVaV em 7 amostras. Quatro dessas amostras apresentaram infecção mista, indicando que o desenvolvimento de sintomas depende de fatores abióticos, como temperatura. A inoculação via extrato vegetal a partir de plantas de alface com infecção mista pelo MLBVV e LBVaV foi realizada a 16°C/ 10°C (dia/noite) e fotoperíodo de 11 horas, verificando-se que o MLBVV foi transmitido para Nicotiana tabacum TNN, N. rustica, N. occidentalis, Chenopodium quinoa e para as cultivares de alface Trocadero e White Boston, enquanto o LBVaV foi transmitido apenas para a alface White Boston. Entretanto, nenhuma destas plantas apresentou sintomas da doença, com exceção de C. quinoa que apresentou sintomas de lesões locais. Plantio em solo proveniente de áreas com histórico da doença de Mogi das Cruzes permitiu a transmissão do LBVaV para alface cv. White Boston e do MLBVV para alface cv. Trocadero e White Boston, embora apenas a cv. White Boston tenha apresentado sintomas da doença. Em conjunto, estes resultados demonstram a dificuldade de transmissão de ambos os vírus, mesmo em condições de laboratório. Abstract in english The occurrence of big vein disease symptoms and the association of Lettuce big-vein associated virus (LBVaV) and Mirafiori lettuce big-vein virus (MLBVV) was evaluated by RT-PCR using specific primers for both viruses. A total of 366 symptomatic plants were collected during June and September 2004 a [...] nd during April and July 2005 at Bauru, Campinas and Mogi das Cruzes in São Paulo state, and 18 symptomless plants were collected in Mogi das Cruzes on December 2004. Mixed infection was detected in 76,2% of the symptomatic plants, 11,5% had only MLBVV and 6,6% had only LBVaV. In the symptomless plants collected in areas with high incidence of the disease throughout the winter, MLBVV was found in 9 plants and LBVaV in 7 plants. Four plants had both viruses, indicating that symptom development depends on abiotic factors, such as temperature. Plants with MLBVV and LBVaV (mixed infection) were used as source of virus in a host range assay at 16C/ 10°C (day/ night) and 11h light period. MLBVV was transmitted to Nicotiana tabacum TNN, N. rustica, N. occidentalis, Chenopodium quinoa and lettuce cv. Trocadero and White Boston, while LBVaV was transmitted only to lettuce cv. White Boston. No symptons could be verified for these plants with the exception of C. quinoa that showed local lesions. Transmission through soil in areas with high incidence of the disease was observed for LBVaV to lettuce cv. White Boston and MLBVV for lettuce cv. Trocadero and White Boston, but only cv. White Boston showed symptoms. Together, these results demonstrate the difficulties in transmitting both viruses, even under controlled laboratory conditions.

Márcio Martinello, Sanches; Renate, Krause-Sakate; Francisco Murilo, Zerbini; Marlene, Rosales; Olivier, Le Gall; Marcelo Agenor, Pavan.

2007-12-01

302

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

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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)

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

303

Effect of Sulfur Blended N-Fertilizers on Nitrogen Use Efficiency and Quality of Lettuce Yield  

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Full Text Available Volatilization of NH3 is a major factor affects ammonical fertilizer use efficiency particularly when N-fertilizers are surface applied to sandy soil characterized by high pH values and low CEC. Effect of blending various N-fertilizers; urea, U, ammonium sulfate, AS, ammonium nitrate, AN and di-ammonium phosphate, DAP; with elemental sulfur, on fertilizer-N utilization and quality of lettuce yield were studied. The results of lettuce yield grown in greenhouse showed significant increase in lettuce fresh yield (ranging from 9.8-18.9% of treatments received S comparing with those received no S. The effect of S on dry matter of leaves and stems was insignificant. Total N content of leaves and stems showed a significant increase varied between 10.4-20.6 and 8.4-18.5%, respectively. Total-N uptake by lettuce plants treated with sulfur-blended fertilizers was increased by 20%(U-52(AN%. Also, an increase in N recovery reached 70% of the applied was observed for sulfur- blended N- fertilizer treatments, instead of 39-52% of those received no S. Nitrate and sulfate contents of lettuce dry matter were significantly increased using S-blended fertilizers particularly in the case of ammonium nitrate (AN and ammonium sulphate (AS. The results of soil analysis showed significant decrease in soil pH in the treatments received S blended fertilizer compared to those received no S. On the other hand, electrical conductivity increased significantly from 1.8-2.1 to 2.1-3.2 dS m?1 as a result of S addition. Insignificant increase in both SO4 and NH4 contents were recorded for S treated samples.

K.N. Al-Redhaiman

2003-01-01

304

Effect of different concentrations of diluted seawater on yield and quality of lettuce  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english This study was carried out to investigate the effects of irrigating lettuce (Lactuca sativa L. cv. Funly) with different concentrations of diluted seawater (0%, 2.5%, 5%, 10%, 15%, 20%) on the fresh yield, marketable yield and quality (DM, total soluble solids, titratable acidity, total sugar, vitam [...] in C, NO3-N, protein, and total oxalate content). The experiments were conducted in a greenhouse in the autumn of 2012. The fresh yield, marketable yield, and DM of lettuce irrigated with 2.5% and 5% seawater were similar to those of control, but these parameters decreased in response to 10% seawater, and the lowest values were obtained in response to 20% seawater. The 2.5% seawater treatment had no effect on the vitamin C and NO3-N content, but both significantly decreased when lettuce was irrigated with seawater concentrations higher than 2.5%. Total soluble solids, total sugar, and protein content significantly increased in response to low salinity (2.5% and 5%) but decreased in response to increasing seawater stress. The titratable acidity values remained unchanged under the various saline conditions. Irrigation with diluted seawater did not affect the total oxalate content up to a concentration of 5%, but increasing the concentration of seawater above 5% increased oxalate content. The results of this study demonstrated that low concentrations of seawater are suitable for lettuce production and lettuce can be grown successfully using diluted seawater at concentrations of 2.5% and 5%.

Ahmet, Turhan; Hayrettin, Kuscu; Nese, Ozmen; Mehmet, Sitki Serbeci; Ali, Osman Demir.

2014-03-01

305

Factors important for the shelf-life of minimally processed lettuce  

DEFF Research Database (Denmark)

The minimally processed vegetable industry has been increasing rapidly due to change in lifestyle. Both women and men work outside home and have less time to cook and need more convenience and time saving products, which also present fresh and healthy characteristics. Iceberg lettuce (Lactuca sativa L.) is one of the most popular fresh-cut vegetables. Although an increase in the number of mixed salads in retail food chains is evident, their short shelf-life due to rapid browning and off-odour is a problem that need research. Therefore, the aim of this PhD project was to investigate factors 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 expressed as brown area fraction. Cut lettuce was stored at 5°C for 6 days and plus 1 day at room temperature (day 7). Changes in browning were assessed at 2, 6 and 7 days of storage using image analysis. The result showed an increase in browning as time and temperature of storage increased. It was concluded that this technique can be used for measuring the browning in cut lettuce. Few studies are done on the formation of volatiles in cut lettuce. Temperature of storage and methods of preparation that minimized quality loss are highly desirable. As such, cutting direction and storage temperature were investigated to elucidate their influence on aroma formation and respiration rate in minimally processed lettuce, are presented in paper II. Lettuce was cut longitudinal and transverse to the mid-rib and stored at 6 and 10°C for 4 and 5 days. Changes in respiration rate were analyzed through the storage time, and aroma analysis was carried out after 4 and 5 days of storage in January and March, respectively. Respiration rate increased with increasing storage temperatures. Aroma formation was also influenced by storage temperature. Higher storage temperature allowed the increase of -longipinene, 2-methylbutanal and 3-methylbutanal. Transversal cut to the rib was strongly related with volatiles of lipoxygenase (LOX) pathway i.e. cis-3-hexenal, cis-3-hexenol and trans-2-hexenol, meanwhile longitudinal cut enhanced the formation of volatiles from other metabolic routes. Therefore, it was concluded that transversal cut cause a more severe damage to the tissue than longitudinal cut based on aroma production of LOX volatiles. It has been indicated that cultivar, season, packaging and storage time influence the type and concentration of volatile compounds, browning, chemical constituents and texture in vegetables. As part of this project, a more integrated study was undertaken for first time in lettuce to our knowledge. The study took into account the influence of cultivar, season, packaging and storage time. In order to achieve this, iceberg lettuce cultivars Platinas, Diamantinas and Morinas were harvested from June to September 2009. Lettuces were minimally processed and stored under three different treatments: two passive modified atmosphere packaging (MAP) built up by films of different permeabilities, F1 (OPALEN 65 AF) and F2 (OPP/PE-L 2040 AF), and storage in air. All packages were stored at 5°C. Gas composition, volatile compounds, physicochemical constituents, PPO activity and browning were assessed at 1, 5, 8 and 11 days of storage in packaged lettuce, whereas in air stored samples only at 1 and 5 days of storage. Additionally, respiration rate was only assessed in air stored samples and GC-O analysis was undertaken after 1 and 11 days of storage for cultivar Morinas packaged in passive MAP F2 in September. The study was divided into three

Deza Durand, Karla Michelle

2013-01-01

306

Alface minimamente processada: uma revisão / Minimally processed lettuce: a review  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Segurança e qualidade na produção de alimentos frescos são dependentes da microflora. Cada etapa da cadeia de produção desde o plantio até o consumo final influencia a qualidade microbiológica do alimento. Manipulação inadequada e ausência de procedimentos adequados, como a não sanitização dos equip [...] amentos utilizados no beneficiamento, levam a um incremento do crescimento microbiano, podendo comprometer a qualidade e segurança de frutas e vegetais frescos. Por razões de ordem econômica e higiênica, o consumo de vegetais frescos pré-preparados, "prontos para consumo" (ready-to-eat), tornou-se bastante popular, pois se encontram disponíveis já higienizados e embalados nos mais diversos formatos, isto é, minimamente processados. Etapas de processamento como a picagem e o corte normalmente incrementam a população de microorganismos, diminuindo, conseqüentemente, a vida-de-prateleira do alimento. A utilização de técnicas para estender a vida-de-prateleira de um produto alimentício pode incrementar os riscos com problemas correlacionados com a segurança alimentar. O uso adequado de desinfetantes pode complementar um programa de sanitização, mas pode não obter sucesso absoluto na erradicação de microorganismos patogênicos em alimentos pré-contaminados. O objetivo desta revisão é apresentar os principais aspectos envolvendo a qualidade e segurança na produção da alface picada minimamente processada. Abstract in english Quality and safety of fresh produce depend on their microbial flora. Every step from production to consumption will influence the microbiology of fresh produce. Improper handling and unsanitary equipment lead to an increase in populations of microorganisms in fresh fruits and vegetables and can comp [...] romise quality and safety. For reasons of expense, labor and hygiene, fresh prepacked vegetables have become very popular, since they are already peeled, sliced, shredded, that is, minimally processed. Processing steps such as cutting usually increase the populations of microorganisms and developing shorten shelf life. The use of techniques to extend shelf life can increase the risk of developing safety problems and therefore need to be carefully evaluated. Proper use of disinfectants can complement an effective sanitization program but should not be relied upon to eliminate pathogenic microorganisms from contaminated produce. The aim of this review article is to present quality and safety aspects of minimal processing of ready-to-eat shredded lettuce.

Liliane Corrêa, MAISTRO.

307

Levantamento revela a predominância do Lettuce mottle virus em três regiões produtoras de alface no Estado de São Paulo Frequency of LMV, LeMoV and BiMV in three lettuce producing areas from São Paulo State  

Directory of Open Access Journals (Sweden)

Full Text Available Entre os problemas fitossanitários da cultura da alface estão as doenças causadas por vírus. Três vírus causam sintomas de mosaico praticamente indistinguíveis: o Lettuce mosaic virus (LMV, Potyvirus, o Lettuce mottle virus (LeMoV, Sequivirus e o Bidens mosaic virus (BiMV, Potyvirus. Através de RT-PCR utilizando-se oligonucleotídeos específicos para cada um destes vírus, amostras de alface e plantas invasoras, preferencialmente com sintoma de mosaico, foram coletadas em campos de produção de alface das regiões de Mogi das Cruzes, Campinas e Bauru no Estado de São Paulo e analisadas para a presença dos vírus. Verificou-se que o LeMoV foi o vírus encontrado com maior freqüência, seguido do LMV. A ocorrência de BiMV em alface foi extremamente baixa e restrita às regiões de Campinas e Bauru, onde também foi verificado em plantas invasoras como Bidens pilosa e Galinsoga parviflora. Esta ultima é hospedeira dos três vírus.Among the phytosanitary problems affecting lettuce culture are the diseases caused by viruses. Three viruses cause almost indistinguishable mosaic symptoms: Lettuce mosaic virus (LMV, Potyvirus, Lettuce mottle virus (LeMoV, Sequivirus and Bidens mosaic virus (BiMV, Potyvirus. By RT-PCR using specific primers for each virus, lettuce and weed samples, preferably with mosaic symptoms, and collected from lettuce fields in the regions of Mogi das Cruzes, Campinas and Bauru, São Paulo State, Brazil, were analyzed for the presence of these viruses. LeMoV was the most frequently found virus, followed by LMV. The occurrence of BiMV in lettuce was extremely low and restricted to the regions of Campinas and Bauru, where it was also found in weeds such as Bidens pilosa and Galinsoga parviflora. The latter plant is the host of these three viruses.

Bruno Rossitto De Marchi

2012-09-01

308

Levantamento revela a predominância do Lettuce mottle virus em três regiões produtoras de alface no Estado de São Paulo Frequency of LMV, LeMoV and BiMV in three lettuce producing areas from São Paulo State  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Entre os problemas fitossanitários da cultura da alface estão as doenças causadas por vírus. Três vírus causam sintomas de mosaico praticamente indistinguíveis: o Lettuce mosaic virus (LMV, Potyvirus), o Lettuce mottle virus (LeMoV, Sequivirus) e o Bidens mosaic virus (BiMV, Potyvirus). Através de RT-PCR utilizando-se oligonucleotídeos específicos para cada um destes vírus, amostras de alface e plantas invasoras, preferencialmente com sintoma de mosaico, foram coletadas em campos d...

Bruno Rossitto De Marchi; David Marques de Almeida Spadotti; Milena Leite de Oliveira; Márcio Martinello Sanches; Renate Krause-Sakate; Marcelo Agenor Pavan

2012-01-01

309

Levantamento revela a predominância do Lettuce mottle virus em três regiões produtoras de alface no Estado de São Paulo / Frequency of LMV, LeMoV and BiMV in three lettuce producing areas from São Paulo State  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Entre os problemas fitossanitários da cultura da alface estão as doenças causadas por vírus. Três vírus causam sintomas de mosaico praticamente indistinguíveis: o Lettuce mosaic virus (LMV, Potyvirus), o Lettuce mottle virus (LeMoV, Sequivirus) e o Bidens mosaic virus (BiMV, Potyvirus). Através de R [...] T-PCR utilizando-se oligonucleotídeos específicos para cada um destes vírus, amostras de alface e plantas invasoras, preferencialmente com sintoma de mosaico, foram coletadas em campos de produção de alface das regiões de Mogi das Cruzes, Campinas e Bauru no Estado de São Paulo e analisadas para a presença dos vírus. Verificou-se que o LeMoV foi o vírus encontrado com maior freqüência, seguido do LMV. A ocorrência de BiMV em alface foi extremamente baixa e restrita às regiões de Campinas e Bauru, onde também foi verificado em plantas invasoras como Bidens pilosa e Galinsoga parviflora. Esta ultima é hospedeira dos três vírus. Abstract in english Among the phytosanitary problems affecting lettuce culture are the diseases caused by viruses. Three viruses cause almost indistinguishable mosaic symptoms: Lettuce mosaic virus (LMV, Potyvirus), Lettuce mottle virus (LeMoV, Sequivirus) and Bidens mosaic virus (BiMV, Potyvirus). By RT-PCR using spec [...] ific primers for each virus, lettuce and weed samples, preferably with mosaic symptoms, and collected from lettuce fields in the regions of Mogi das Cruzes, Campinas and Bauru, São Paulo State, Brazil, were analyzed for the presence of these viruses. LeMoV was the most frequently found virus, followed by LMV. The occurrence of BiMV in lettuce was extremely low and restricted to the regions of Campinas and Bauru, where it was also found in weeds such as Bidens pilosa and Galinsoga parviflora. The latter plant is the host of these three viruses.

Bruno Rossitto, De Marchi; David Marques de Almeida, Spadotti; Milena Leite de, Oliveira; Márcio Martinello, Sanches; Renate, Krause-Sakate; Marcelo Agenor, Pavan.

2012-09-01

310

Prevalence of Lettuce mosaic virus - common strain on three lettuce producing areas from São Paulo State / Prevalência da estirpe comum de Lettuce mosaic virus em três regiões produtoras de alface do estado de São Paulo  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O LMV ocorre em todo o mundo e é considerado um dos patógenos mais importantes para a cultura da alface. De acordo com a habilidade em contornar os genes de resistência mo1¹ e mo1² encontrados em alface, os isolados de LMV podem ser dividos em dois sub-grupos: LMV-Most, capazes de contornar a resist [...] ência propiciada por estes genes e de serem transmitidos pela semente nestas cutivares, e LMV-Common, que não são capazes de causar sintomas nestes cultivares, além de serem transmitidos pela semente somente em cultivares suscetíveis. Para avaliar a ocorrência destes dois tipos de isolados de LMV foram coletadas, durante 2002-2005, amostras de alface com sintomas de mosaico em áreas de produção de alface comercial das regiões de Campinas, Mogi das Cruzes e Bauru no estado de São Paulo. O RNA total foi utilizado para detecção por RT-PCR utilizando-se oligonucleotídeos universais para LMV que amplificam a porção N-terminal variável da capa protéica, localizada no terminal 3´do genoma. As amostras positivas foram analisadas por um segundo primer que amplifica um fragmento da região central (CI-VPg) do genoma viral. Um total de 1362 amostras foram avaliadas, tendo sido detectado o LMV em 504 amostras (37,29%). O LMV-Common prevaleceu em variedades suscetíveis (77,3%). O LMV-Most foi encontrado frequentemente associado a variedades portadoras do gene de tolerância mo1¹. Apesar da existência dos LMV-Most capazes de contornar a resistência em alface, estes não predominam em nossa condições. Abstract in english LMV is one of the most important pathogens of lettuce worldwide. Based on their ability to overcome the resistance genes mo1¹ and mo1² in lettuce, isolates can be divided in two types: LMV-Most, which can infect and are seed-borne in cultivars containing the mo1 gene and LMV-Common, which do not cau [...] se symptoms on these cultivars and are seed transmitted only in susceptible cultivars. To evaluate the occurrence of these two types of LMV isolates, a survey was carried out during 2002-2005 in three lettuce production areas from São Paulo State. Total RNA was used for the diagnosis of LMV isolates by RT-PCR using universal primers for the variable N-terminus of the capsid protein, in the 3' end of the genome. Positives samples were analyzed by a second RT-PCR using specifics primers for LMV-Most isolates designed to amplify a fragment from the central region (CI-VPg) of the genome. A total of 1362 samples showing mosaic symptoms were collected and 504 (37.29 %) were positives for LMV. On susceptible lettuce cultivars, LMV-Common was prevalent (77.3%). LMV-Most was found frequently associated with tolerant (mo1¹) lettuce cultivars. Susceptible cultivars correspond today for most of the area of lettuce production. So, despite the ability of LMV-Most isolates to overcome the resistance provided by the recessive mo1¹ gene, they are not prevalent in the conditions of São Paulo State.

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

2008-06-01

311

Prevalence of Lettuce mosaic virus - common strain on three lettuce producing areas from São Paulo State Prevalência da estirpe comum de Lettuce mosaic virus em três regiões produtoras de alface do estado de São Paulo  

Directory of Open Access Journals (Sweden)

Full Text Available LMV is one of the most important pathogens of lettuce worldwide. Based on their ability to overcome the resistance genes mo1¹ and mo1² in lettuce, isolates can be divided in two types: LMV-Most, which can infect and are seed-borne in cultivars containing the mo1 gene and LMV-Common, which do not cause symptoms on these cultivars and are seed transmitted only in susceptible cultivars. To evaluate the occurrence of these two types of LMV isolates, a survey was carried out during 2002-2005 in three lettuce production areas from São Paulo State. Total RNA was used for the diagnosis of LMV isolates by RT-PCR using universal primers for the variable N-terminus of the capsid protein, in the 3' end of the genome. Positives samples were analyzed by a second RT-PCR using specifics primers for LMV-Most isolates designed to amplify a fragment from the central region (CI-VPg of the genome. A total of 1362 samples showing mosaic symptoms were collected and 504 (37.29 % were positives for LMV. On susceptible lettuce cultivars, LMV-Common was prevalent (77.3%. LMV-Most was found frequently associated with tolerant (mo1¹ lettuce cultivars. Susceptible cultivars correspond today for most of the area of lettuce production. So, despite the ability of LMV-Most isolates to overcome the resistance provided by the recessive mo1¹ gene, they are not prevalent in the conditions of São Paulo State.O LMV ocorre em todo o mundo e é considerado um dos patógenos mais importantes para a cultura da alface. De acordo com a habilidade em contornar os genes de resistência mo1¹ e mo1² encontrados em alface, os isolados de LMV podem ser dividos em dois sub-grupos: LMV-Most, capazes de contornar a resistência propiciada por estes genes e de serem transmitidos pela semente nestas cutivares, e LMV-Common, que não são capazes de causar sintomas nestes cultivares, além de serem transmitidos pela semente somente em cultivares suscetíveis. Para avaliar a ocorrência destes dois tipos de isolados de LMV foram coletadas, durante 2002-2005, amostras de alface com sintomas de mosaico em áreas de produção de alface comercial das regiões de Campinas, Mogi das Cruzes e Bauru no estado de São Paulo. O RNA total foi utilizado para detecção por RT-PCR utilizando-se oligonucleotídeos universais para LMV que amplificam a porção N-terminal variável da capa protéica, localizada no terminal 3´do genoma. As amostras positivas foram analisadas por um segundo primer que amplifica um fragmento da região central (CI-VPg do genoma viral. Um total de 1362 amostras foram avaliadas, tendo sido detectado o LMV em 504 amostras (37,29%. O LMV-Common prevaleceu em variedades suscetíveis (77,3%. O LMV-Most foi encontrado frequentemente associado a variedades portadoras do gene de tolerância mo1¹. Apesar da existência dos LMV-Most capazes de contornar a resistência em alface, estes não predominam em nossa condições.

Ana Carolina Firmino

2008-06-01

312

Prevalence of Lettuce mosaic virus - common strain on three lettuce producing areas from São Paulo State / Prevalência da estirpe comum de Lettuce mosaic virus em três regiões produtoras de alface do estado de São Paulo  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O LMV ocorre em todo o mundo e é considerado um dos patógenos mais importantes para a cultura da alface. De acordo com a habilidade em contornar os genes de resistência mo1¹ e mo1² encontrados em alface, os isolados de LMV podem ser dividos em dois sub-grupos: LMV-Most, capazes de contornar a resist [...] ência propiciada por estes genes e de serem transmitidos pela semente nestas cutivares, e LMV-Common, que não são capazes de causar sintomas nestes cultivares, além de serem transmitidos pela semente somente em cultivares suscetíveis. Para avaliar a ocorrência destes dois tipos de isolados de LMV foram coletadas, durante 2002-2005, amostras de alface com sintomas de mosaico em áreas de produção de alface comercial das regiões de Campinas, Mogi das Cruzes e Bauru no estado de São Paulo. O RNA total foi utilizado para detecção por RT-PCR utilizando-se oligonucleotídeos universais para LMV que amplificam a porção N-terminal variável da capa protéica, localizada no terminal 3´do genoma. As amostras positivas foram analisadas por um segundo primer que amplifica um fragmento da região central (CI-VPg) do genoma viral. Um total de 1362 amostras foram avaliadas, tendo sido detectado o LMV em 504 amostras (37,29%). O LMV-Common prevaleceu em variedades suscetíveis (77,3%). O LMV-Most foi encontrado frequentemente associado a variedades portadoras do gene de tolerância mo1¹. Apesar da existência dos LMV-Most capazes de contornar a resistência em alface, estes não predominam em nossa condições. Abstract in english LMV is one of the most important pathogens of lettuce worldwide. Based on their ability to overcome the resistance genes mo1¹ and mo1² in lettuce, isolates can be divided in two types: LMV-Most, which can infect and are seed-borne in cultivars containing the mo1 gene and LMV-Common, which do not cau [...] se symptoms on these cultivars and are seed transmitted only in susceptible cultivars. To evaluate the occurrence of these two types of LMV isolates, a survey was carried out during 2002-2005 in three lettuce production areas from São Paulo State. Total RNA was used for the diagnosis of LMV isolates by RT-PCR using universal primers for the variable N-terminus of the capsid protein, in the 3' end of the genome. Positives samples were analyzed by a second RT-PCR using specifics primers for LMV-Most isolates designed to amplify a fragment from the central region (CI-VPg) of the genome. A total of 1362 samples showing mosaic symptoms were collected and 504 (37.29 %) were positives for LMV. On susceptible lettuce cultivars, LMV-Common was prevalent (77.3%). LMV-Most was found frequently associated with tolerant (mo1¹) lettuce cultivars. Susceptible cultivars correspond today for most of the area of lettuce production. So, despite the ability of LMV-Most isolates to overcome the resistance provided by the recessive mo1¹ gene, they are not prevalent in the conditions of São Paulo State.

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

313

A probabilistic model of norovirus disease burden associated with greywater irrigation of home-produced lettuce in Melbourne, Australia.  

Science.gov (United States)

The reuse of domestic greywater has become common in Australia, especially during periods of extreme drought. Greywater is typically used in a raw, untreated form, primarily for landscape irrigation, but more than a quarter of greywater users irrigate vegetable gardens with the water, despite government advice against this practice. Greywater can be contaminated with enteric pathogens and may therefore pose a health risk if irrigated produce is consumed raw. A quantitative microbial risk assessment (QMRA) model was constructed to estimate the norovirus disease burden associated with consumption of greywater-irrigated lettuce. The annual disease burdens (95th percentile; DALYs per person) attributed to greywater irrigation ranged from 2 × 10(-8) to 5 × 10(-4), depending on the source of greywater and the existence of produce washing within households. Accounting for the prevalence of produce-washing behaviours across Melbourne, the model predicted annual disease burdens ranging from 4 × 10(-9) for bathroom water use only to 3 × 10(-6) for laundry water use only, and accounting for the proportionate use of each greywater type, the annual disease burden was 2 × 10(-6). We recommend the preferential use of bathroom water over laundry water where possible as this would reduce the annual burden of disease to align with the current Australian recycled water guidelines, which recommend a threshold of 10(-6) DALYs per person. It is also important to consider other exposure pathways, particularly considering the high secondary attack rate of norovirus, as it is highly likely that the estimated norovirus disease burden associated with greywater irrigation of vegetables is negligible relative to household contact with an infected individual. PMID:23290124

Fiona Barker, S; O'Toole, Joanne; Sinclair, Martha I; Leder, Karin; Malawaraarachchi, Manori; Hamilton, Andrew J

2013-03-01

314

Comparison of Different Washing and Disinfection Protocols Used by Food Services in Southern Brazil for Lettuce (Lactuca sativa  

Directory of Open Access Journals (Sweden)

Full Text Available Different protocols have been used for washing and disinfecting leafy vegetables in Brazilian food services, however its effect on microbial reduction was barely studied. The aim of this study was to evaluate the effectiveness of lettuce washing and disinfecting protocols used by food services. The treatments evaluated were: washing in potable tap water (T1; washing and dipping in potable tap water (T2; washing with potable tap water and dipping in a solution of sodium hypochlorite (200 ppm of free chlorine for 15 min (T3; and 30 min (T4; washing with potable tap water and dipping in 2% vinegar solution (T5; and 20% vinegar solution (T6. After the treatments, the samples were microbiologically evaluated to measure bacterial reductions. The microbial counts showed that the mean total mesophile reductions were: 0.64 log for T1, 0.75 log for T2, 2.06 log for T3, 2.46 log for T4, 1.68 log for T5 and 1.72 log for T6, and the mean total coliform reductions were: 1.11 log for T1, 1.09 log for T2, 2.29 log for T3, 2.35 log for T4, 1.6 log for T5 and 2.09 log for T6. Based on these results it can be concluded that protocols which used 200 ppm sodium hypochlorite for 15 to 30 min (T3 e T4, were the most effective, followed by treatment with 20% vinegar solution (T6. The latter method, however, turned the lettuce dark during the distribution period.

Ana Beatriz Almeida de Oliveira

2012-01-01

315

Effect of Vermicompost and Compost on Lettuce Production Efecto de Vermicompost y Compost en la Producción de Lechuga  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A greenhouse study was conducted to evaluate the effect on total growth and leaf nutritional content in lettuce (Lactuca sativa L.) in the Agrotechnology Sciences Department of the Universidad Autonoma de Chihuahua, Mexico in 2007. Three types of fertilization treatments were analyzed: two organic and one conventional or inorganic. Both vermicompost and compost were produced from cattle manure in a 25-wk process. The study included 12 experimental units made up of lettuce plantlets var. Great...

Adriana Hernández; Hugo Castillo; Dámaris Ojeda; Ana Arras; Julio López; Esteban Sánchez

2010-01-01

316

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Scheffler Brian; McHale Leah; Truco María; Ochoa Oswaldo; Michelmore Richard; Simko Ivan; Pechenick Dov

2009-01-01

317

Identification of Fusarium oxysporum f. sp. lactucae race 1 as the causal agent of lettuce wilt in Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english The objective of this work was to assess the virulence to lettuce cultivars and host specificity and to identify races of Fusarium oxysporum f. sp. lactucae (FOLac) isolates associated with lettuce wilt in Brazil. Thirty-one isolates identified based on morphology were inoculated in a set of lettuce [...] cultivars for race determination. Plantlets of 'Elisa', 'Vera', and 'Red Salad Bowl' cultivars were inoculated with all isolates using a root-dipping method. Isolates were also inoculated in species of Asteraceae and other botanical families. 'Elisa' and 'Vera' were susceptible to 27 isolates while 'Red Salad Bowl' was resistant to all isolates. Plants other than lettuce were not infected by any of the isolates, suggesting their specificity to lettuce. All pathogenic isolates were assigned to race 1 and used to evaluate a PCR protocol with primers targeting race 1. Only amplicons associated with race 1 pattern were observed for all pathogenic isolates but not for one non-pathogenic isolate, thus leading us to conclude that FOLac race 1 is so far the sole causal agent of lettuce wilt in Brazil.

Cléia S., Cabral; Kátia R., Brunelli; Hélcio, Costa; Maria Esther de N., Fonseca; Leonardo S., Boiteux; Ailton, Reis.

2014-06-01

318

Construction of transplastomic lettuce (Lactuca sativa) dominantly producing astaxanthin fatty acid esters and detailed chemical analysis of generated carotenoids.  

Science.gov (United States)

The plastid genome of lettuce (Lactuca sativa L.) cv. Berkeley was site-specifically modified with the addition of three transgenes, which encoded ?,?-carotenoid 3,3'-hydroxylase (CrtZ) and ?,?-carotenoid 4,4'-ketolase (4,4'-oxygenase; CrtW) from a marine bacterium Brevundimonas sp. strain SD212, and isopentenyl diphosphate isomerase from a marine bacterium Paracoccus sp. strain N81106. Constructed transplastomic lettuce plants were able to grow on soil at a growth rate similar to that of non-transformed lettuce cv. Berkeley and generate flowers and seeds. The germination ratio of the lettuce transformants (T0) (98.8%) was higher than that of non-transformed lettuce (93.1 %). The transplastomic lettuce (T1) leaves produced the astaxanthin fatty acid (myristate or palmitate) diester (49.2% of total carotenoids), astaxanthin monoester (18.2%), and the free forms of astaxanthin (10.0%) and the other ketocarotenoids (17.5%), which indicated that artificial ketocarotenoids corresponded to 94.9% of total carotenoids (230 ?g/g fresh weight). Native carotenoids were there lactucaxanthin (3.8%) and lutein (1.3 %) only. This is the first report to structurally identify the astaxanthin esters biosynthesized in transgenic or transplastomic plants producing astaxanthin. The singlet oxygen-quenching activity of the total carotenoids extracted from the transplastomic leaves was similar to that of astaxanthin (mostly esterified) from the green algae Haematococcus pluvialis. PMID:24287848

Harada, Hisashi; Maoka, Takashi; Osawa, Ayako; Hattan, Jun-Ichiro; Kanamoto, Hirosuke; Shindo, Kazutoshi; Otomatsu, Toshihiko; Misawa, Norihiko

2014-04-01

319

Podridão de raízes causada por Pythium aphanidermatum, em cultivares de alface produzidas em sistema hidropônico Root rot caused by Pythium aphanidermatum of lettuce cultivars produced in a hydroponic system  

Directory of Open Access Journals (Sweden)

Full Text Available A podridão de raízes, causada por Pythium aphanidermatum e outras espécies de Pythium, é a principal doença da alface cultivada em sistemas hidropônicos no Brasil. O presente trabalho teve como objetivo avaliar quatro cultivares comerciais de alface em relação à sensibilidade a podridão de raízes, causada por P. aphanidermatum. Os estudos foram realizados em placas de Petri contendo ágar-água com plântulas de alface das cultivares crespa (Vera e Verônica e lisa (Regina e Elisa, infestadas ou não com o patógeno. Com as mesmas cultivares foram realizados quatro experimentos em sistemas hidropônicos (Nutrient Film Technique, sendo dois em estufa coberta com plástico e sombrite e dois em estufa coberta apenas com plástico. As plântulas, infectadas ou não com P. aphanidermatum, foram transplantadas para os sistemas infestados ou não. Foi avaliada a severidade da doença e o desenvolvimento das plantas. Todas as cultivares foram suscetíveis à podridão de raízes nos experimentos realizados in vitro e in vivo. A presença do sombrite não reduziu a podridão de raízes em cultivares de alface produzidas no sistema hidropônico. A cultivar Regina apresentou maior massa de matéria seca da parte aérea e das raízes, na presença ou ausência do patógeno, sendo a mais indicada para o cultivo hidropônico na época mais quente do ano.Lettuce root rot caused by Pythium aphanidermatum and other Pythium species is the main disease in hydroponic systems in Brazil. The present work aimed to evaluate the behavior of four commercial lettuce cultivars as to their sensitivity to root rot caused by P. aphanidermatum in hydroponic systems. Experiments were conducted in Petri dishes containing water-agar medium and seedlings of the crisp head lettuce cultivars (Vera and Verônica and leafy lettuce cultivars (Regina and Elisa, infested or not with the pathogen. With the same cultivars, four other experiments were carried out in hydroponic systems (Nutrient Film Technique, two in a shaded greenhouse and the other two in a conventional greenhouse. Seedlings infected or not with P. aphanidermatum were transplanted to hydroponic systems infested or not with the pathogen. The disease severity and the plant development were evaluated. All cultivars were susceptible to root rot in both in vitro and in vivo experiments. The shading did not reduce root rot in the lettuce cultivars in hydroponic system. The cultivar Regina showed higher shoot and root dry mass in the presence or absence of the pathogen, constituting thus the most suitable cultivar for hydroponic systems during the hottest period of the year.

Zayame Vegette Pinto

2011-12-01

320

Podridão de raízes causada por Pythium aphanidermatum, em cultivares de alface produzidas em sistema hidropônico / Root rot caused by Pythium aphanidermatum of lettuce cultivars produced in a hydroponic system  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A podridão de raízes, causada por Pythium aphanidermatum e outras espécies de Pythium, é a principal doença da alface cultivada em sistemas hidropônicos no Brasil. O presente trabalho teve como objetivo avaliar quatro cultivares comerciais de alface em relação à sensibilidade a podridão de raízes, c [...] ausada por P. aphanidermatum. Os estudos foram realizados em placas de Petri contendo ágar-água com plântulas de alface das cultivares crespa (Vera e Verônica) e lisa (Regina e Elisa), infestadas ou não com o patógeno. Com as mesmas cultivares foram realizados quatro experimentos em sistemas hidropônicos (Nutrient Film Technique), sendo dois em estufa coberta com plástico e sombrite e dois em estufa coberta apenas com plástico. As plântulas, infectadas ou não com P. aphanidermatum, foram transplantadas para os sistemas infestados ou não. Foi avaliada a severidade da doença e o desenvolvimento das plantas. Todas as cultivares foram suscetíveis à podridão de raízes nos experimentos realizados in vitro e in vivo. A presença do sombrite não reduziu a podridão de raízes em cultivares de alface produzidas no sistema hidropônico. A cultivar Regina apresentou maior massa de matéria seca da parte aérea e das raízes, na presença ou ausência do patógeno, sendo a mais indicada para o cultivo hidropônico na época mais quente do ano. Abstract in english Lettuce root rot caused by Pythium aphanidermatum and other Pythium species is the main disease in hydroponic systems in Brazil. The present work aimed to evaluate the behavior of four commercial lettuce cultivars as to their sensitivity to root rot caused by P. aphanidermatum in hydroponic systems. [...] Experiments were conducted in Petri dishes containing water-agar medium and seedlings of the crisp head lettuce cultivars (Vera and Verônica) and leafy lettuce cultivars (Regina and Elisa), infested or not with the pathogen. With the same cultivars, four other experiments were carried out in hydroponic systems (Nutrient Film Technique), two in a shaded greenhouse and the other two in a conventional greenhouse. Seedlings infected or not with P. aphanidermatum were transplanted to hydroponic systems infested or not with the pathogen. The disease severity and the plant development were evaluated. All cultivars were susceptible to root rot in both in vitro and in vivo experiments. The shading did not reduce root rot in the lettuce cultivars in hydroponic system. The cultivar Regina showed higher shoot and root dry mass in the presence or absence of the pathogen, constituting thus the most suitable cultivar for hydroponic systems during the hottest period of the year.

Zayame Vegette, Pinto; Matheus Aparecido Pereira, Cipriano; José Abrahão Haddad, Galvão; Wagner, Bettiol; Flávia Rodrigues Alves, Patrício; Amaury da Silva dos, Santos.

2011-12-01