WorldWideScience
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Growth of plants in solution culture containing low levels of chromium. [Tomato, lettuce, duckweed  

Energy Technology Data Exchange (ETDEWEB)

Chromium was not required for normal growth of romaine lettuce (Lactuca sativa L. subsp. longifolia), tomato (Lycopersicon esculentum Mill.), wheat (Triticum aestivum L.), or bean (Phaseolus vulgaris L.) in solution culture containing 3.8 X 10/sup -4/ ..mu..M Cr. Plants grown on this purified nutrient solution contained an average of 22 ng Cr/g dry weight. Duckweed (Lemna sp.) grew and reproduced normally on a dilute nutrient solution containing 3.8 X 20/sup -5/ ..mu..M Cr.

Huffman, E.W.D. Jr.; Allaway, W.H.

1973-01-01

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

OpenAIRE

Inadequate use of water resources reduces their availability and therefore, research focused on their reutilization is required. This work evaluated the sanitary quality of lettuce irrigated with reused water in comparison with samples of lettuce commercialized in Taubaté (SP) market. An experiment was developed in a greenhouse with three beds of lettuce irrigated with reused water and three beds of lettuce irrigated with urban water supply. After lettuce biological cycle had been completed,...

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

2011-01-01

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

Science.gov (United States)

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

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

2014-01-01

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

Science.gov (United States)

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

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

2014-01-01

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

Directory of Open Access Journals (Sweden)

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

Claudinei Fonseca Souza

2011-08-01

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

OpenAIRE

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

Rahman, Mokhlasur; Huys, Geert; Rahman, Motiur; Albert, M. John; Ku?hn, Inger; Mo?llby, Roland

2006-01-01

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Decontaminative effect of frozen acidic electrolyzed water on lettuce.  

Science.gov (United States)

We investigated the effects of frozen acidic electrolyzed water (AcEW) on lettuce during storage in a styrene-foam container. The lettuce was kept at 2 to 3 degrees C for 24 h. Populations of aerobic bacteria associated with lettuce packed in frozen AcEW were reduced by 1.5 log CFU/g after storage for 24 h. With frozen tap water, no microorganism populations tested in this study were reduced. A frozen mixture of AcEW and alkaline electrolyzed water (AlEW) also failed to reduce populations of microorganisms associated with lettuce. Although chlorine gas was produced by frozen AcEW, it was not produced by the AcEW-AlEW mixture. This result indicates that the main factor in the decontaminative effect of frozen AcEW was the production of chlorine gas. Accordingly, low-temperature storage and decontamination could be achieved simultaneously with frozen AcEW during distribution. PMID:11848576

Koseki, Shigenobu; Fujiwara, Kazuhiro; Itoh, Kazuhiko

2002-02-01

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

OpenAIRE

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...

Kadayifci Abdullah; Tuylu Gokhan Ismail; Ucar Yusuf; Cakmak Belgin

2004-01-01

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Effect of electrolyzed water for reduction of foodborne pathogens on lettuce and spinach.  

Science.gov (United States)

The ability of electrolyzed water (EW) to inactivate foodborne pathogens on the surfaces of lettuce and spinach was investigated. Lettuce and spinach leaves were inoculated with a cocktail of 3 strains each of Escherichia col O157:H7, Salmnonella Typhimurium, and Listeria monocytogenes and treated with acidic electrolyzed water (AC-EW), alkaline electrolyzed water (AK-EW), alkaline electrolyzed water followed by acidic electrolyzed water (sequential treatment, AK-EW + AC-EW), deionized water followed by acidic electrolyzed water (sequential treatment, DW + AC-EW), and deionized water (control, DW) for 15, 30 s, and 1, 3, and 5 min at room temperature (22 +/- 2 degrees C). For all 3 pathogens, the same pattern of microbial reduction on lettuce and spinach were apparent. The relative efficacy of reduction was AC-EW > DW + AC-EW approximately = AK-EW + AC-EW > AK-EW > control. After a 3-min treatment of AC-EW, the 3 tested pathogens were reduced below the detection limit (0.7 log). DW + AC-EW and AK-EW + AC-EW produced the same levels of reduction after 5 min when compared to the control. AK-EW did not reduce levels of pathogens even after a 5-min treatment on lettuce and spinach. Results suggest that AC-EW treatment was able to significantly reduce populations of the 3 tested pathogens from the surfaces of lettuce and spinach with increasing time of exposure. PMID:19241556

Park, E J; Alexander, E; Taylor, G A; Costa, R; Kang, D H

2008-08-01

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Adjuvants Affect Duckweed (Lemna minor Control with Pelargonic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available Duckweeds (Lemna spp. are small, free floating aquatic plants that flourish on stagnant or slow moving water surfaces throughout the world. Members of the genus are among the smallest flowering plants, providing food for fish and fowl, but their aggressive growth and invasive tendencies make them formidable aquatic weeds, which when uncontrolled can result in oxygen depletion, fish kills, and death of submerged aquatic plants. Pelargonic acid is a fatty acid naturally occurring in many plants and animals, and present in many foods. AXXE® (65% pelargonic acid, BioSafe Systems LLC is a potential organic herbicide. Research was conducted to determine the impact of spray adjuvants on duckweed control with pelargonic acid. Duckweed was sprayed with 7 pelargonic acid concentrations (0, 1, 2, 4, 6, 8, and 10% v/v combined with 1 of 3 adjuvant treatments [control, BioLink (30% garlic extracts, 10% yucca extracts, and 60% water at 0.5% v:v, and orange oil (90% d’limonene and 10% inert ingredients at 0.5% v:v]. Visual ratings, measuring percentage duckweed control (percentage dead, were collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 days after treatment (DAT. The experiment was conductive twice using 5 replications. Pelargonic acid phytotoxicity increased as spray concentration increased whether an adjuvant was used or not. The 6% pelargonic acid concentration resulted in 90% or greater duckweed control for all adjuvant treatments (control, BioLink, and Orange Oil across all evaluation dates (1 – 11 DAT. The addition of either adjuvant applied at the 6% pelargonic acid concentration produced consistently greater duckweed control across all evaluation dates (1 – 11 DAT compared to the control (no adjuvant. The 8% pelargonic acid rate produced excellent (97% or greater duckweed control for all adjuvant treatments, with consistently better control with the BioLink adjuvant and typically with the orange oil, compared to the control. At the 10% rate all treatments provided outstanding (99% or greater control at all evaluation dates, with no significant differences among adjuvant treatments. The research demonstrated the effectiveness of pelargonic acid in controlling duckweed when applied over-the-top. The addition of the BioLink adjuvant often increased the duckweed control compared to the control (no adjuvant. The authors suggest that further research should investigate whether higher rates of these adjuvants or the use other adjuvants would provide satisfactory duckweed control at lower pelargonic acid application rates and the economic implications of the changes.

Charles L. Webber III

2014-11-01

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

Science.gov (United States)

Lettuce and leafy greens have been implicated in multiple foodborne disease outbreaks. This study quantifies cross contamination between lettuce pieces in a small-scale home environment. A five-strain cocktail of relevant Escherichia coli O157:H7 strains was used. Bacterial transfer between single inoculated lettuce leaf pieces to 10 non-inoculated lettuce leaf pieces that were washed in a stainless steel bowl of water for 30 s, 1 min, 2 min, and 5 min was quantified. Regardless of washing time, the wash water became contaminated with 90-99% of bacteria originally present on the inoculated lettuce leaf piece. The E. coli O157:H7 concentration on initially inoculated leaf pieces was reduced ?2 log CFU. Each initially uncontaminated lettuce leaf piece had ?1% of the E. coli O157:H7 from the inoculated lettuce piece transferred to it after washing, with more transfer occurring during the shortest (30 s) and longest (5 min) wash times. In all cases the log percent transfer rates were essentially normally distributed. In all scenarios, most of the E. coli O157:H7 (90-99%) transferred from the inoculated lettuce pieces to the wash water. Washing with plain tap water reduces levels of E. coli O157:H7 on the inoculated lettuce leaf pieces, but also spreads contamination to previously uncontaminated leaf pieces. PMID:25475312

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

2015-04-01

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

Directory of Open Access Journals (Sweden)

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

OpenAIRE

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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Growing duckweed for biofuel production: a review.  

Science.gov (United States)

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

Cui, W; Cheng, J J

2015-01-01

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

OpenAIRE

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

Alkhader, Asad M. F.; Abu Rayyan, Azmi M.

2013-01-01

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Differences in the binding of human norovirus to and from romaine lettuce and raspberries by water and electrolyzed waters.  

Science.gov (United States)

Food contamination by human norovirus (hNoV) is a major cause of gastrointestinal disease. We evaluated the effectiveness of removing inoculated hNoV from the surfaces of raspberries and romaine lettuce by a simple wash in tap water and in different forms of electrolyzed water (EW), including acidic EW (AEW), neutral EW (NEW), and basic EW (BEW). A simple rinsing or soaking in water was able to remove >95% of hNoV from surface-inoculated raspberries. In contrast, only 75% of hNoV was removed from surface-inoculated romaine lettuce by rinsing in tap water. An AEW wash enhanced the binding of hNoV to raspberries and lettuce. Only 7.5% (±10%) and 4% (±3.1%) of hNoV were removed by AEW wash from surface-inoculated raspberries and lettuce, respectively. When raspberries and lettuce were prewashed with NEW or BEW prior to surface inoculation, an AEW wash likewise resulted in significantly less removal of hNoV compared with untreated samples. A prewash with AEW significantly decreased the removal of hNoV from raspberries and lettuce when they were washed with NEW, from 90.6 to 51% and from 76 to 51.3% , respectively. There are minimal or no improvements gained by use of any of the EWs instead of a regular tap water wash in removal of hNoV from produce. However, use of AEW shows a significant decrease in the removal of hNoV from contaminated produce compared with other water rinses. The ability to remove hNoV from different types of produce varies, possibly due to differences among types of ligand-like molecules that bind hNoV. The distribution of hNoV on raspberries and lettuce was studied using recombinant Norwalk-like particles (rNVLP). By immunofluorescence microscopy, we were able to observe binding of rNVLP only to vein areas of romaine lettuce, suggesting that the virus was binding to specific molecules in these areas. Random binding of rNVLP occurred only with raspberries prewashed with AEW or washed with AEW. PMID:21819668

Tian, Peng; Yang, David; Mandrell, Robert

2011-08-01

19

Efficacy of acidic electrolyzed water ice for pathogen control on lettuce.  

Science.gov (United States)

Acidic electrolyzed water (AcEW) was used as frozen AcEW (AcEW-ice) for inactivation of Listeria monocytogenes and Escherichia coli O157:H7 on lettuce. AcEW-ice was prepared from AcEW with 20, 50, 100, and 200 ppm of available chlorine by freezing at -40 degrees C and generated 30, 70, 150, and 240 ppm of chlorine gas (Cl2), respectively. The AcEW-ice was placed into styrene-foam containers with lettuce samples at 20 degrees C for 24 h. Although AcEW-ice generating 30 ppm Cl2 had no effect on L. monocytogenes cell counts, AcEW-ice generating 70 to 240 ppm of Cl2 significantly (P acid content in the lettuce. The weight ratio of lettuce to AcEW-ice required was determined to be over 1:10. The bactericidal effect of AcEW-ice appeared within the first 2 h. The use of AcEW-ice provides simultaneously for low temperature storage and inactivation of bacteria. PMID:15553639

Koseki, Shigenobu; Isobe, Seiichiro; Itoh, Kazuhiko

2004-11-01

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EFFECTIVENESS OF ELECTROLYZED OXIDIZING WATER FOR INACTIVATING Listeria monocytogenes IN LETTUCE  

OpenAIRE

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 deioniz...

Casadiego Laíd Paola; Cuartas Vivian Rocío; Mercado Marcela; Díaz Milciades; Carrascal Ana Karina

2005-01-01

21

EFFECTIVENESS OF ELECTROLYZED OXIDIZING WATER FOR INACTIVATING Listeria monocytogenes IN LETTUCE  

Directory of Open Access Journals (Sweden)

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

22

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

Directory of Open Access Journals (Sweden)

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

A. M. Snow

2008-01-01

23

Effect of ozonated water treatment on microbial control and on browning of iceberg lettuce (Lactuca sativa L.).  

Science.gov (United States)

We examined the effect of ozonated water treatment on microbial control and quality of cut iceberg lettuce (Lactuca sativa L.). Fresh-cut lettuce was washed in ozonated water (3, 5, and 10 ppm) for 5 min at ambient temperature. The native bacterial population on the lettuce declined in response to a rise in ozone concentration. However, there was no further bacterial reduction (1.4 log CFU/g) above 5 ppm ozone. Although ozonated water treatment increased the phenylalanine ammonia lyase (PAL) activity of the lettuce stored at 10 degrees C compared with the water wash treatment after 1 day of storage, the concentration of ozone did not affect PAL activity. The a* value of the residue of the lettuce methanol extracts, which reflects the extent of browning, increased dramatically in lettuce treated with 10 ppm ozonated water compared with other treatments. Treatment with 3 or 5 ppm ozonated water resulted in more rapid changes in the a* value than after the water treatment. The combined treatment of hot water (50 degrees C, 2.5 min) followed by ozonated water (5 ppm, 2.5 min) had the same bactericidal effect as treatment with ozonated water (5 ppm, 5 min) or sodium hypochlorite (NaOCl, 200 ppm, 5 min), giving a reduction in bacteria numbers of 1.2 to 1.4 log CFU/g. The ascorbic acid content of the lettuce was not affected by these treatments. The combined treatment of hot water followed by ozonated water greatly inhibited PAL activity for up to 3 days of storage at 10 degrees C. Treatment with this combination greatly suppressed increases in the a* value, thus retarding the progress of browning compared with other treatments throughout the 6-day storage. NaOCl treatment also inhibited browning for up to 3 days of storage. Bacterial populations on the lettuce treated with sanitizers were initially reduced but then showed rapid growth compared with that of the water wash treatment, which did not reduce bacterial counts initially. PMID:16416913

Koseki, Shigenobu; Isobe, Seiichiro

2006-01-01

24

Use of freshwater algae and duckweeds for phytotoxicity testing.  

Science.gov (United States)

The toxicity of contaminated water of different origins and chemicals [Cr(III), Pb(II), Cu(II), Cd(II), pyrene] were tested using four test species: the alga Selenastrum capricornutum (new name Raphidocelis subcapitata), the duckweed Lemna minor, and the crustaceans Thamnocephalus platyurus and Daphnia magna. On the basis of the results obtained, the sensitivity of plant species and problems concerning the interpretation of the phytotoxicity data are discussed. The data indicated that the sensitivities of crustaceans and plant species both to individual contaminants and to mixtures are unpredictable and that there is no reason to consider plant species less sensitive than animal species. Lemna minor is more sensitive than Selenastrum capricornutum. With colored samples, duckweed is preferable for toxicity testing. To raise the predictive utility of the phytotoxicity data, it is recommended that natural water be used in the test procedure. PMID:15269918

Blinova, Irina

2004-08-01

25

Nutrients valorisation via duckweed-based wastewater treatment and aquaculture  

OpenAIRE

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

El-shafai, S. A. A. M.

2004-01-01

26

Effect of wash water temperature and chlorination on phenolic metabolism and browning of stored iceberg lettuce photosynthetic and vascular tissues.  

Science.gov (United States)

Cut tissues from distinct anatomical locations in iceberg lettuce (Lactuca sativa L.) were subjected to washing in cold (4 degrees C) and warm (47 degrees C) water with or without chlorine to assess their propensity to discoloration during storage. Total protein (Bradford method) and phenolic (TPH; Folin-Ciocalteu method) contents and polyphenol oxidase (PPO; spectrophotometric method using catechol as a substrate), peroxidase (POD; guaiacol substrate), and phenylalanine ammonia-lyase (PAL; phenylalanine substrate) activities were determined in photosynthetic and vascular tissue from outer and inner leaves. Unprocessed photosynthetic and inner leaf tissues had significantly higher (P lettuce washed at 4 degrees C. These results showed that inherent differences between tissues affect phenolic metabolism and browning in stored, fresh-cut lettuce. PMID:12137468

Fukumoto, Lana R; Toivonen, Peter M A; Delaquis, Pascal J

2002-07-31

27

Response of duckweed to various concentrations of selenite.  

Science.gov (United States)

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

Mechora, Spela; Stibilj, Vekoslava; Germ, Mateja

2014-07-16

28

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

OpenAIRE

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

29

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

Science.gov (United States)

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

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

2012-04-01

30

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

Directory of Open Access Journals (Sweden)

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

Inge Van Der Linden

2014-09-01

31

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

32

Monitoring and Measuring the biomass of the floating macrophytes by numerical image processing: Case duckweeds (Lemna minor) in Waste Stablisation Ponds  

OpenAIRE

In hot countries temperature conditions allow the use of various WSP technologies, including floating macrophytes. We studied duckweeds and they have been used for industrial or domestic waste water treatment. However, the vegetable carpet formed on the water surface must be managed in order to maintain a good efficiency. The duckweeds must be harvested regularly. Otherwise when the biomass is getting too large there is some overlap, mortality increases, and dead cells sink and degrade at the...

Tangou Tabou, Thierry; Musibono Eyul Anki, Dieudonne?; Vasel, Jean-luc

2011-01-01

33

Status of duckweed genomics and transcriptomics.  

Science.gov (United States)

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

Wang, W; Messing, J

2015-01-01

34

Characterisation of circadian rhythms of various duckweeds.  

Science.gov (United States)

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

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

2015-01-01

35

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 (Irrigation with contaminated water together with highest soil uranium available concentration (10 to 13 mg/kg) had negative 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

36

Slicing under chlorinated water improves the disinfection of fresh-cut romaine lettuce.  

Science.gov (United States)

The aim of this study was to determine whether the timing or mode of application influences the antimicrobial efficacy of a sodium hypochlorite solution against microorganisms on fresh-cut Romaine lettuce. Lettuce leaves were treated with a solution of sodium hypochlorite containing 70 mg liter(-1) free chlorine prior to slicing (WLS), while submerged in the solution (CWS), or after slicing (PCS), the last being common practice in the fresh-cut industry. Immediate antimicrobial effects were determined from analyses performed directly after treatment, while delayed effects were derived from analysis of packaged samples stored at 4 and 15°C. Experiments were performed with both uninoculated and inoculated whole leaves, using Escherichia coli O157:H7 from a type collection as an inoculum. The CWS treatment provided the greatest initial reductions in aerobic plate counts of E. coli O157:H7 populations, followed by PCS and WLS. The advantage afforded by the CWS approach was maintained over 10 days in storage at 4°C. In addition, it was noted that the visual quality attributes of the fresh-cut lettuce from the CWS approach were better than those from the other two treatments. These results collectively suggest that slicing lettuce under a sanitizer solution could provide better disinfection of fresh-cut Romaine lettuce than the current practice of washing with sanitizer after cutting has taken place. PMID:22186056

Toivonen, Peter M A; Lu, Changwen; Delaquis, Pascal; Bach, Susan

2011-12-01

37

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

Directory of Open Access Journals (Sweden)

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

38

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

39

Use of Neutral Electrolysed Water (EW) for Quality Maintenance and Shelf-Life Extension of Minimally Processed Lettuce  

OpenAIRE

Experiments were conducted to determine the effectiveness of different treatments based on the use of neutral electrolysed water (EW) on fresh-cut lettuce. EW was diluted to obtain different free chlorine concentrations (120, 60 and 12 ppm) and compared with standard washing treatment of 120 ppm chlorine solution. Shelf-life quality and safety markers were studied at the beginning and at the end of the 7-day storage at 4 ºC. The use of EW decreased the respiration rate of the samples which m...

Rico, Daniel; Martin-diana, Ana Belen; Barry-ryan, Catherine; Frias, Jesus Maria; Henehan, Gary; Barat, Jose?

2008-01-01

40

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

OpenAIRE

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

41

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

Science.gov (United States)

This study compared the efficacy of chlorine (20-200 ppm), acidic electrolyzed water (50 ppm chlorine, pH 2.6), acidified sodium chlorite (20-200 ppm chlorite ion concentration, Sanova), and aqueous chlorine dioxide (20-200 ppm chlorite ion concentration, TriNova) washes in reducing populations of Escherichia coli O157:H7 on artificially inoculated lettuce. Fresh-cut leaves of Romaine or Iceberg lettuce were inoculated by immersion in water containing E. coli O157:H7 (8 log CFU/ml) for 5 min and dried in a salad spinner. Leaves (25 g) were then washed for 2 min, immediately or following 24 h of storage at 4 degrees C. The washing treatments containing chlorite ion concentrations of 100 and 200 ppm were the most effective against E. coli O157:H7 populations on Iceberg lettuce, with log reductions as high as 1.25 log CFU/g and 1.05 log CFU/g for TriNova and Sanova wash treatments, respectively. All other wash treatments resulted in population reductions of less than 1 log CFU/g. Chlorine (200 ppm), TriNova, Sanova, and acidic electrolyzed water were all equally effective against E. coli O157:H7 on Romaine, with log reductions of approximately 1 log CFU/g. The 20 ppm chlorine wash was as effective as the deionized water wash in reducing populations of E. coli O157:H7 on Romaine and Iceberg lettuce. Scanning electron microscopy indicated that E. coli O157:H7 that was incorporated into biofilms or located in damage lettuce tissue remained on the lettuce leaf, while individual cells on undamaged leaf surfaces were more likely to be washed away. PMID:19428137

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

2009-06-30

42

Ecotoxicological assessment of industrial effluent using duckweed (Lemna minor L.) as a test organism.  

Science.gov (United States)

This study aimed at assessing the toxic effects of industrial effluents using duckweed (Lemna minor L.) plants as a test system. Growth inhibition test according to standardized protocol (ISO 20079) was performed. The suitability of the Comet assay (indicates DNA damage) and certain parameters such as peroxidase activity and lipid peroxidation level, as biomarkers for environmental monitoring was evaluated. The water samples were collected monthly over a 3-month period from the stream near the industrial estate of Savski Marof, Croatia. All samples caused inhibition of growth rates based on frond number and biomass as well as decrease of chlorophylls content. In contrast, peroxidase activity, malondialdehyde content and tail extent moment (measure of DNA strand breaks) markedly increased. Obtained data demonstrate the relevance of duckweed as sensitive indicators of water quality as well as the significance of selected biological parameters in the reliable assessment of phyto- and genotoxic potential of complex wastewaters. PMID:19757030

Radi?, Sandra; Stipanicev, Drazenka; Cvjetko, Petra; Mikeli?, Ivanka Lovrenci?; Rajci?, Marija Marijanovi?; Sirac, Sinisa; Pevalek-Kozlina, Branka; Pavlica, Mirjana

2010-01-01

43

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

Science.gov (United States)

There are few studies on the presence of extended-spectrum ?-lactamases and AmpC ?-lactamases (ESBL/AmpC) in bacteria that contaminate vegetables. The role of the production environment in ESBL/AmpC gene transmission is poorly understood. The occurrence of ESBL/AmpC in Escherichia coli (n?=?46) from lettuce and irrigation water and the role of irrigation water in the transmission of resistant E.?coli were studied. The presence of ESBL/AmpC, genetic similarity and phylogeny were typed using genotypic and phenotypic techniques. The frequency of ?-lactamase gene transfer was studied in vitro. ESBLs/AmpC were detected in 35 isolates (76%). Fourteen isolates (30%) produced both ESBLs/AmpC. Prevalence was highest in E.?coli from lettuce (90%). Twenty-two isolates (48%) were multi-resistant with between two and five ESBL/AmpC genes. The major ESBL determinant was the CTX-M type (34 isolates). DHA (33% of isolates) were the dominant AmpC ? lactamases. There was a high conjugation efficiency among the isolates, ranging from 3.5?×?10(-2) to 1?×?10(-2) ?±?1.4?×?10(-1) transconjugants per recipient. Water isolates showed a significantly higher conjugation frequency than those from lettuce. A high degree of genetic relatedness between E.?coli from irrigation water and lettuce indicated possible common ancestry and pathway of transmission. PMID:25488608

Njage, Patrick M K; Buys, Elna M

2014-12-01

44

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

45

Influence of inoculation method, spot inoculation site, and inoculation size on the efficacy of acidic electrolyzed water against pathogens on lettuce.  

Science.gov (United States)

The influence of bacterial inoculation methods on the efficacy of sanitizers against pathogens was examined. Dip and spot inoculation methods were employed in this study to evaluate the effectiveness of acidic electrolyzed water (AcEW) and chlorinated water (200 ppm free available chlorine) against Escherichia coli O157:H7 and Salmonella spp. Ten pieces of lettuce leaf (5 by 5 cm) were inoculated by each method then immersed in 1.5 liters of AcEW, chlorinated water, or sterile distilled water for 1 min with agitation (150 rpm) at room temperature. The outer (abaxial) and inner (adaxial) surfaces of the lettuce leaf were distinguished in the spot inoculation. Initial inoculated pathogen population was in the range 7.3 to 7.8 log CFU/g. Treatment with AcEW and chlorinated water resulted in a 1 log CFU/g or less reduction of E. coli O157:H7 and Salmonella populations inoculated with the dip method. Spot inoculation of the inner surface of the lettuce leaf with AcEW and chlorinated water reduced the number of E. coli O157:H7 and Salmonella by approximately 2.7 and 2.5 log CFU/g, respectively. Spot inoculation of the outer surface of the lettuce leaf with both sanitizers resulted in approximately 4.6 and 4.4 log CFU/g reductions of E. coli O157:H7 and Salmonella, respectively. The influence of inoculation population size was also examined. Each sanitizer could not completely eliminate the pathogens when E. coli O157:H7 and Salmonella cells inoculated on the lettuce were of low population size (10(3) to 10(4) CFU/g), regardless of the inoculation technique. PMID:14627276

Koseki, Shigenobu; Yoshida, Kyoichiro; Kamitani, Yoshinori; Itoh, Kazuhiko

2003-11-01

46

Tapioca-starch wastewater toxicity characterized by Microtox and duckweed tests  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-12-01

47

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

48

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

Science.gov (United States)

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

Farnese, Fs; Oliveira, Ja; Lima, Fs; Leão, Ga; Gusman, Gs; Silva, Lc

2014-08-01

49

The strength of limiting factors for duckweed during algal competition  

OpenAIRE

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

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

2005-01-01

50

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  

Directory of Open Access Journals (Sweden)

Full Text Available Objetivou-se, com este trabalho, avaliar o crescimento, o consumo hídrico e a extração de nutrientes, por alface (Lactuca sativa L. em sistema hidropônico NFT (fluxo laminar de nutrientes, com a utilização de águas salinas no preparo da solução nutritiva e reposição da lâmina diária evapotranspirada. 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.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

2012-02-01

51

Transfer of Escherichia coli O157:H7 from soil, water, and manure contaminated with low numbers of the pathogen to lettuce plants.  

Science.gov (United States)

The sources of contamination of leafy greens remain unclear, but it is evident that contaminated water, soil amendments, and wildlife likely contribute. The objective of the present study was to determine transfer of low numbers of Escherichia coli O157:H7 from soil, manure-amended soil, and water to growing lettuce plants. Lettuce plants, young (12 days of age) or mature (30 days of age), were grown in soil, manure-amended soil, or irrigated with water containing 10(1), 10(2), 10(3), or 10(4) CFU E. coli O157:H7 per g or ml. Harvested plants were processed to determine whether E. coli O157:H7 was associated with the entire plant or within internal locations. Young plants (12 days) were harvested at 1, 10, 20, and 30 days postexposure. No samples were positive for E. coli O157:H7 after direct plating of serial dilutions. Enrichment of all samples from young plants exposed to contaminated soil, manure-amended soil, and irrigation water demonstrated that approximately 21% (113 of 552) of plants were positive for E. coli O157:H7. Approximately 30% (36 of 120) of the mature plants initially irrigated with or grown in contaminated soil (including manure-amended soil) for 15 days were positive for E. coli O157:H7. Based on sterilization of surface tissue, E. coli O157:H7 was in protected locations of lettuce tissue. The results suggest that lettuce exposed to, and grown in the presence of, low numbers of E. coli O157:H7 may become contaminated and thus present a human health risk. PMID:19903393

Mootian, Gabriel; Wu, Wen-Hsuan; Matthews, Karl R

2009-11-01

52

Reduction of bacteria on spinach, lettuce, and surfaces in food service areas using neutral electrolyzed oxidizing water.  

Science.gov (United States)

Food safety issues and increases in food borne illnesses have promulgated the development of new sanitation methods to eliminate pathogenic organisms on foods and surfaces in food service areas. Electrolyzed oxidizing water (EO water) shows promise as an environmentally friendly broad spectrum microbial decontamination agent. EO water is generated by the passage of a dilute salt solution ( approximately 1% NaCl) through an electrochemical cell. This electrolytic process converts chloride ions and water molecules into chlorine oxidants (Cl(2), HOCl/ClO(-)). At a near-neutral pH (pH 6.3-6.5), the predominant chemical species is the highly biocidal hypochlorous acid species (HOCl) with the oxidation reduction potential (ORP) of the solution ranging from 800 to 900mV. The biocidal activity of near-neutral EO water was evaluated at 25 degrees C using pure cultures of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Treatment of these organisms, in pure culture, with EO water at concentrations of 20, 50, 100, and 120ppm total residual chlorine (TRC) and 10min of contact time resulted in 100% inactivation of all five organisms (reduction of 6.1-6.7log(10)CFU/mL). Spray treatment of surfaces in food service areas with EO water containing 278-310ppm TRC (pH 6.38) resulted in a 79-100% reduction of microbial growth. Dip (10min) treatment of spinach at 100 and 120ppm TRC resulted in a 4.0-5.0log(10)CFU/mL reduction of bacterial counts for all organisms tested. Dipping (10min) of lettuce at 100 and 120ppm TRC reduced bacterial counts of E. coli by 0.24-0.25log(10)CFU/mL and reduced all other organisms by 2.43-3.81log(10)CFU/mL. PMID:17993375

Guentzel, Jane L; Liang Lam, Kang; Callan, Michael A; Emmons, Stuart A; Dunham, Valgene L

2008-02-01

53

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

54

Hurdle enhancement of slightly acidic electrolyzed water antimicrobial efficacy on Chinese cabbage, lettuce, sesame leaf and spinach using ultrasonication and water wash.  

Science.gov (United States)

Slightly acidic electrolyzed water (SAEW) is well known as a good sanitizer against foodborne pathogens on fresh vegetables. However, microbial reductions from SAEW treatment are not enough to ensure produce safety. Therefore, it is necessary to improve its antimicrobial efficiency by combining it with other appropriate approaches. This study examined the microbicidal activity of SAEW (pH 5.2-5.5, oxidation reduction potential 500-600 mV, available chlorine concentration 21-22 mg/l) on Chinese cabbage, lettuce, sesame leaf and spinach, four common fresh vegetables in Korea under same laboratory conditions. Subsequently, effects of ultrasonication and water wash to enhance the sanitizing efficacy of SAEW were studied, separately. Finally, an optimized simple and easy approach consisting of simultaneous SAEW treatment with ultrasonication (3 min) followed by water wash (150 rpm, 1 min) was developed (SAEW + US-WW). This newly developed hurdle treatment significantly enhanced the microbial reductions compared to SAEW treatment alone, SAEW treatment with ultrasonication (SAEW + US) and SAEW treatment followed by water wash (SAEW-WW) at room temperature (23 ± 2 °C). Microbial reductions of yeasts and molds, total bacteria count and inoculated Escherichia coli O157:H7 and Listeria monocytogenes were in the range of 1.76-2.8 log cfu/g on different samples using the new hurdle approach. PMID:23764218

Forghani, Fereidoun; Oh, Deog-Hwan

2013-10-01

55

EXPRESSION OF ENDOGLUCANASE E1 IN TRANSGENIC DUCKWEED LEMNA MINOR  

Science.gov (United States)

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

56

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.

2010-07-01

57

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

58

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

59

EXPRESSION AND CHARACTERIZATION OF ACIDOTHERMUS CELLULOLYTICUS E1 ENDOGLUCANASE IN TRANSGENIC DUCKWEED LEMNA MINOR 8627  

Science.gov (United States)

Endoglucanase E1 from Acidothermus cellulolyticus was expressed cytosolically under control of the cauliflower mosaic virus 35S promoter in transgenic duckweed, Lemna minor 8627. The selected transgenic duckweed line Cel25IX-15 generated using Agrobacterium-mediated transformation exhibited no phen...

60

Microbiological quality and safety assessment of lettuce production in Brazil.  

Science.gov (United States)

The microbiological quality and safety of lettuce during primary production in Brazil were determined by enumeration of hygiene indicators Escherichia coli, coliforms and enterococci and detection of enteric pathogens Salmonella and E. coli O157:H7 in organic fertilizers, soil, irrigation water, lettuce crops, harvest boxes and worker's hands taken from six different lettuce farms throughout the crop growth cycle. Generic E. coli was a suitable indicator for the presence of Salmonella and E. coli O157:H7, while coliforms and enterococci were not. Few pathogens were detected: 5 salmonellae and 2 E. coli O157:H7 from 260 samples, of which only one was lettuce and the others were manure, soil and water. Most (5/7) pathogens were isolated from the same farm and all were from organic production. Statistical analysis revealed the following environmental and agro-technical risk factors for increased microbial load and pathogen prevalence in lettuce production: high temperature, flooding of lettuce fields, application of contaminated organic fertilizer, irrigation with water of inferior quality and large distances between the field and toilets. Control of the composting process of organic fertilizers and the irrigation water quality appear most crucial to improve and/or maintain the microbiological quality and safety during the primary production of lettuce. PMID:24829142

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

2014-07-01

61

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

OpenAIRE

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

Talukdar, M. Z. H.

2012-01-01

62

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

OpenAIRE

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 fingerling...

Juan Esquivel; Débora Machado Fracalossi; Rodrigues, Joa?o Bosco R.; Tavares, Fla?via A.; Rodrigo Roubach

2008-01-01

63

Modeling growth of Escherichia coli O157:H7 in fresh-cut lettuce treated with neutral electrolyzed water and under modified atmosphere packaging.  

Science.gov (United States)

The purpose of this study was to evaluate and model the growth of Escherichia coli O157:H7 in fresh-cut lettuce submitted to a neutral electrolyzed water (NEW) treatment, packaged in passive modified atmosphere and subsequently stored at different temperatures (4, 8, 13, 16°C) for a maximum of 27 days. Results indicated that E. coli O157:H7 was able to grow at 8, 13, and 16°C, and declined at 4°C. However at 8°C, the lag time lasted 19 days, above the typical shelf-life time for this type of products. A secondary model predicting growth rate as a function of temperature was developed based on a square-root function. A comparison with literature data indicated that the growth predicted by the model for E. coli O157:H7 was again lower than those observed with other disinfection treatments or packaging conditions (chlorinated water, untreated product, NEW, etc.). The specific models here developed might be applied to predict growth in products treated with NEW and to improve existing quantitative risk assessments. PMID:24583345

Posada-Izquierdo, Guiomar D; Pérez-Rodríguez, Fernando; López-Gálvez, Francisco; Allende, Ana; Gil, María I; Zurera, Gonzalo

2014-05-01

64

CHEMICAL AND PHYTOCHEMICAL COMPOSITION OF WILD LETTUCE (LAUNAEA TARAXACIFOLIA  

Directory of Open Access Journals (Sweden)

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

ARAWANDE, JACOB OLALEKAN

2013-01-01

65

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

Science.gov (United States)

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

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

2012-11-30

66

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

OpenAIRE

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

Zimmo, O.

2003-01-01

67

Nitrogen transformations and removal mechanisms in algal and duckweed stabilisation ponds  

OpenAIRE

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

Zimmo, O.

2003-01-01

68

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

OpenAIRE

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

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

2012-01-01

69

EFEITO DO CLORO NA ÁGUA DE LAVAGEM PARA DESINFECÇÃO DE ALFACE MINIMAMENTE PROCESSADA EFFECT OF CHLORINE IN THE WASHING WATER FOR DESINFECTION OF MINIMALLY PROCESSED LETTUCE  

Directory of Open Access Journals (Sweden)

Full Text Available Este trabalho de pesquisa foi desenvolvido com o objetivo de verificar a eficácia de diferentes concentrações de cloro utilizadas como agente sanitizante na água de lavagem de alface(Lactuca sativa L., do tipo americana, minimamente processada. Na matéria-prima foram realizadas contagens de bolores, leveduras e coliformes totais. No produto final foram realizadas contagens de bolores e leveduras, coliformes totais e avaliação sensorial. O processamento mínimo da alface compreendeu as seguintes etapas: corte do talo, desfolhamento da cabeça, primeira seleção, primeira lavagem, segunda seleção, corte em tiras, segunda lavagem, tratamento de imersão em soluções contendo 70, 100 e 130mg/L de cloro, centrifugação, acondicionamento em sacos plásticos e armazenamento a 2°C e a 20°C. Os resultados mostraram que a imersão em solução contendo 70mg/L de cloro confere a alface minimamente processada uma vida-útil de seis dias e em solução contendo 100 e 130mg/L, nove dias e que o seu aroma, textura e gosto não foram afetados por estes tratamentos.This research was carried out aiming at evaluating the efficacy of different concentrations of chlorine used as a sanitizer in the washing water of minimally processed lettuce (Lactuca sativa L.. Total coliform and mould and yeast counts were performed on the raw material. The same microbiological exams plus a sensory evaluation were performed on the final product. The minimal processing of the lettuce consisted of cutting, shredding, first selection of leaves, first washing, second selection, manual slicing, second washing, dipping in solutions of 70,100 and 130mg/L of chlorine, spin drying, packaging in polyethylene bags and storage at 2(0C and at 20(0C.The results showed that the chlorine solution containing 70mg/L promoted a shelf-life of 6 days under refrigeration, and the 100 and 130mg/L solutions, 9 days. The sensory characteristics such as texture and flavor were not affected by the treatments studied.

Shirley Aparecida Garcia BERBARI

2001-08-01

70

EFEITO DO CLORO NA ÁGUA DE LAVAGEM PARA DESINFECÇÃO DE ALFACE MINIMAMENTE PROCESSADA / EFFECT OF CHLORINE IN THE WASHING WATER FOR DESINFECTION OF MINIMALLY PROCESSED LETTUCE  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Este trabalho de pesquisa foi desenvolvido com o objetivo de verificar a eficácia de diferentes concentrações de cloro utilizadas como agente sanitizante na água de lavagem de alface(Lactuca sativa L.), do tipo americana, minimamente processada. Na matéria-prima foram realizadas contagens de bolores [...] , leveduras e coliformes totais. No produto final foram realizadas contagens de bolores e leveduras, coliformes totais e avaliação sensorial. O processamento mínimo da alface compreendeu as seguintes etapas: corte do talo, desfolhamento da cabeça, primeira seleção, primeira lavagem, segunda seleção, corte em tiras, segunda lavagem, tratamento de imersão em soluções contendo 70, 100 e 130mg/L de cloro, centrifugação, acondicionamento em sacos plásticos e armazenamento a 2°C e a 20°C. Os resultados mostraram que a imersão em solução contendo 70mg/L de cloro confere a alface minimamente processada uma vida-útil de seis dias e em solução contendo 100 e 130mg/L, nove dias e que o seu aroma, textura e gosto não foram afetados por estes tratamentos. Abstract in english This research was carried out aiming at evaluating the efficacy of different concentrations of chlorine used as a sanitizer in the washing water of minimally processed lettuce (Lactuca sativa L.). Total coliform and mould and yeast counts were performed on the raw material. The same microbiological [...] exams plus a sensory evaluation were performed on the final product. The minimal processing of the lettuce consisted of cutting, shredding, first selection of leaves, first washing, second selection, manual slicing, second washing, dipping in solutions of 70,100 and 130mg/L of chlorine, spin drying, packaging in polyethylene bags and storage at 2(0)C and at 20(0)C.The results showed that the chlorine solution containing 70mg/L promoted a shelf-life of 6 days under refrigeration, and the 100 and 130mg/L solutions, 9 days. The sensory characteristics such as texture and flavor were not affected by the treatments studied.

Shirley Aparecida Garcia, BERBARI; José Eduardo, PASCHOALINO; Neliane F. Arruda, SILVEIRA.

2001-08-01

71

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

72

CHEMICAL AND PHYTOCHEMICAL COMPOSITION OF WILD LETTUCE (LAUNAEA TARAXACIFOLIA)  

OpenAIRE

The study is focus on the proximate, mineral and phytochemical composition of Wild Lettuce and its extractive value in different solvents. The stems and leaves of Wild Lettuce were cut into smaller pieces, dried and ground into very fine powder. The powdery sample was analyzed for proximate and mineral constituents. The powdery sample was further subjected to extraction using acetone, chloroform, ethylacetate, methanol and water. The powdery sample as well as its solvent-extracts was screened...

Arawande, Jacob Olalekan; Amoo, Isiaka Adekunle; Lajide, Labunmi

2013-01-01

73

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

Scientific Electronic Library Online (English)

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

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

2014-11-01

74

Persistence of 14C maneb in lettuce plants an soil  

International Nuclear Information System (INIS)

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

75

Zooming in on the lettuce genome  

OpenAIRE

Lactuca sativa (cultivated lettuce) is the world's most important leafy salad vegetable. Apart from L. sativa , the genus Lactuca contains ca. 75 wild species, potentially useful to improve, for example, taste, texture, and disease resistance of cultivated lettuce. The wild species L. serriola (Prickly Lettuce), L. saligna (Least Lettuce), and L. virosa (Great Lettuce) are commonly used for lettuce improvement. In preliminary experiments, we established that there is a close connection betwee...

Koopman, W. J. M.

2002-01-01

76

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

77

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

78

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

79

Pyrolysis of fast-growing aquatic biomass -Lemna minor (duckweed): Characterization of pyrolysis products.  

Science.gov (United States)

The aim of this work was to conduct the experimental study of pyrolysis of fast-growing aquatic biomass -Lemna minor (commonly known as duckweed) with the emphasis on the characterization of main products of pyrolysis. The yields of pyrolysis gas, pyrolytic oil (bio-oil) and char were determined as a function of pyrolysis temperature and the sweep gas (Ar) flow rate. Thermogravimetric/differential thermogravimetric (TG/DTG) analyses of duckweed samples in inert (helium gas) and oxidative (air) atmosphere revealed differences in the TG/DTG patterns obtained for duckweed and typical plant biomass. The bio-oil samples produced by duckweed pyrolysis at different reaction conditions were analyzed using GC-MS technique. It was found that pyrolysis temperature had minor effect on the bio-oil product slate, but exerted major influence on the relative quantities of the individual pyrolysis products obtained. While, the residence time of the pyrolysis vapors had negligible effect on the yield and composition of the duckweed pyrolysis products. PMID:20598878

Muradov, Nazim; Fidalgo, Beatriz; Gujar, Amit C; T-Raissi, Ali

2010-11-01

80

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

Science.gov (United States)

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

81

Effects of homeopathic arsenicum album, nosode, and gibberellic acid preparations on the growth rate of arsenic-impaired duckweed (Lemna gibba L.).  

Science.gov (United States)

This study evaluated the effects of homeopathically potentized Arsenicum album, nosode, and gibberellic acid in a bioassay with arsenic-stressed duckweed (Lemna gibba L.). The test substances were applied in nine potency levels (17x, 18x, 21x-24x, 28x, 30x, 33x) and compared with controls (unsuccussed and succussed water) regarding their influence on the plant's growth rate. Duckweed was stressed with arsenic(V) for 48 h. Afterwards, plants grew in either potentized substances or water controls for 6 days. Growth rates of frond (leaf) area and frond number were determined with a computerized image analysis system for different time intervals (days 0-2, 2-6, 0-6). Five independent experiments were evaluated for each test substance. Additionally, five water control experiments were analyzed to investigate the stability of the experimental setup (systematic negative control experiments). All experiments were randomized and blinded. The test system exhibited a low coefficient of variation (approximately equal to 1%). Unsuccussed and succussed water did not result in any significant differences in duckweed growth rate. Data from the control and treatment groups were pooled to increase statistical power. Growth rates for days 0-2 were not influenced by any homeopathic preparation. Growth rates for days 2-6 increased after application of potentized Arsenicum album regarding both frond area (p area growth rate only, p < 0.01). Potencies of gibberellic acid did not influence duckweed growth rate. The systematic negative control experiments did not yield any significant effects. Thus, false-positive results can be excluded with high certainty. To conclude, the test system with L. gibba impaired by arsenic(V) was stable and reliable. It yielded evidence for specific effects of homeopathic Arsenicum album preparations and it will provide a valuable tool for future experiments that aim at revealing the mode of action of homeopathic preparations. It may also be useful to investigate the influence of external factors (e.g., heat, electromagnetic radiation) on the effects of homeopathic preparations. PMID:21057725

Jäger, Tim; Scherr, Claudia; Simon, Meinhard; Heusser, Peter; Baumgartner, Stephan

2010-01-01

82

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

83

Microflora of partially processed lettuce.  

OpenAIRE

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

Magnuson, J. A.; King, A. D.; To?ro?k, T.

1990-01-01

84

GROWTH RESPONSE OF THE DUCKWEED LEMNA MINOR TO HEAVY METAL POLLUTION  

OpenAIRE

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

Zerdaoui, N. Khellaf ?. M.

2009-01-01

85

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

Directory of Open Access Journals (Sweden)

Full Text Available

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

ASSUAN DJAMILA IBRAHIM MOGHARBEL

2009-06-01

86

GROWTH RESPONSE OF THE DUCKWEED LEMNA MINOR TO HEAVY METAL POLLUTION  

Directory of Open Access Journals (Sweden)

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

N. Khellaf ? M. Zerdaoui

2009-07-01

87

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

Science.gov (United States)

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

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

2015-01-01

88

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

89

Effect of Grape Seed Extract on Human Norovirus GII.4 and Murine Norovirus 1 in Viral Suspensions, on Stainless Steel Discs, and in Lettuce Wash Water  

OpenAIRE

The anti-norovirus (anti-NoV) effect of grape seed extract (GSE) was examined by plaque assay for murine norovirus 1 (MNV-1), cell-binding reverse transcription-PCR for human NoV GII.4, and saliva-binding enzyme-linked immunosorbent assay for human NoV GII.4 P particles, with or without the presence of interfering substances (dried milk and lettuce extract). GSE at 0.2 and 2 mg/ml was shown to reduce the infectivity of MNV-1 (>3-log PFU/ml) and the specific binding ability of NoV GII.4 to Cac...

Li, Dan; Baert, Leen; Zhang, Dongsheng; Xia, Ming; Zhong, Weiming; Coillie, Els; Jiang, Xi; Uyttendaele, Mieke

2012-01-01

90

Gaseous nitrogen losses during glasshouse cultivation of lettuce on a sandbed  

OpenAIRE

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

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

1994-01-01

91

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

OpenAIRE

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...

P?czu?a W.; Suchora M.

2014-01-01

92

Agronomic efficiency of intercropping tomato and lettuce  

OpenAIRE

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...

Ceci?lio Filho, Arthur B.; Rezende, Bra?ulio L. A.; Barbosa, Jose? C.; Grangeiro, Leilson C.

2011-01-01

93

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

94

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

Science.gov (United States)

This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed. PMID:15036838

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

2004-03-01

95

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

Science.gov (United States)

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

96

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

OpenAIRE

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...

Sowjanya Sree, K.; KLAUS-J. APPENROTH

2014-01-01

97

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

OpenAIRE

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,...

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

2003-01-01

98

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

OpenAIRE

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

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

2013-01-01

99

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

OpenAIRE

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

Al-nozaily, F. A.

2001-01-01

100

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

OpenAIRE

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

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

2012-01-01

101

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

OpenAIRE

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

102

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

103

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

104

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

Science.gov (United States)

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

105

Use of Propolis in the Sanitization of Lettuce  

OpenAIRE

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

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

2014-01-01

106

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

107

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 (promaine lettuce by 2.68 and 1.56 log CFU/g (promaine lettuce throughout the storage time. The natural microbiota on treated lettuce leaves increased during the storage time, but remained similar (p>0.05) 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

108

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

109

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

OpenAIRE

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

El-shafai, S. A. A. M.; El-gohary, F.; Verreth, J. A. J.; Schrama, J. W.; Gijzen, H. J.

2004-01-01

110

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.

2009-06-01

111

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

112

Leaf Age as a Risk Factor in Contamination of Lettuce with Escherichia coli O157:H7 and Salmonella enterica?  

OpenAIRE

Outbreaks of Escherichia coli O157:H7 infections have been linked increasingly to leafy greens, particularly to lettuce. We present here the first evidence that this enteric pathogen can multiply on the leaves of romaine lettuce plants. The increases in population size of E. coli O157:H7 in the phyllosphere of young lettuce plants ranged from 16- to 100-fold under conditions of warm temperature and the presence of free water on the leaves and varied significantly with leaf age. The population...

Brandl, M. T.; Amundson, R.

2008-01-01

113

Phylogenetic relationships of aroids and duckweeds (Araceae) inferred from coding and noncoding plastid DNA.  

Science.gov (United States)

Familial, subfamilial, and tribal monophyly and relationships of aroids and duckweeds were assessed by parsimony and Bayesian phylogenetic analyses of five regions of coding (rbcL, matK) and noncoding plastid DNA (partial trnK intron, trnL intron, trnL-trnF spacer) for exemplars of nearly all aroid and duckweed genera. Our analyses confirm the position of Lemna and its allies (formerly Lemnaceae) within Araceae as the well-supported sister group of all aroids except Gymnostachydoideae and Orontioideae. The last two subfamilies form the sister clade of the rest of the family. Monophyly of subfamilies Orontioideae, Pothoideae, Monsteroideae, and Lasioideae is supported, but Aroideae are paraphyletic if Calla is maintained in its own subfamily (Calloideae). Our results suggest expansion of the recently proposed subfamily Zamioculcadoideae (Zamioculcas, Gonatopus) to include Stylochaeton and identify problems in the current delimitation of tribes Anadendreae, Heteropsideae, and Monstereae (Monsteroideae), Caladieae/Zomicarpeae, and Colocasieae (Aroideae). Canalization of traits of the spathe and spadix considered typical of Araceae evolved after the split of Gymnostachydoideae, Orontioideae, and Lemnoideae. An association with aquatic habitats is a plesiomorphic attribute in Araceae, occurring in the helophytic Orontioideae and free-floating Lemnoideae, but evolving independently in various derived aroid lineages including free-floating Pistia (Aroideae). PMID:21632433

Cabrera, Lidia I; Salazar, Gerardo A; Chase, Mark W; Mayo, Simon J; Bogner, Josef; Dávila, Patricia

2008-09-01

114

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)

115

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

Science.gov (United States)

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

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

2015-01-01

116

Effect of pressure on the vacuum cooling of iceberg lettuce  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-05-15

117

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

OpenAIRE

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

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

2013-01-01

118

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

Directory of Open Access Journals (Sweden)

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

119

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 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

120

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

Science.gov (United States)

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

121

Impact of preinoculation culture conditions on the behavior of Escherichia coli O157:H7 inoculated onto romaine lettuce (Lactuca sativa) plants and cut leaf surfaces.  

Science.gov (United States)

Inoculum preparation methods can impact growth or survival of organisms inoculated into foods, thus complicating direct comparison of results among studies. The objective of this study was to evaluate preinoculation culture preparation for impact on Escherichia coli O157:H7 inoculated onto leaves of romaine lettuce plants and cut leaf surfaces. E. coli O157:H7 was grown quiescently or shaken at 15, 25, or 37 degrees C to different growth phases in tryptic soy or M9 minimal salts broth or agar. Cells were harvested, washed, and suspended in 0.1% peptone, Milli Q water, or well water and refrigerated for 0 or 18 h. Prepared inoculum was spotted onto cut romaine lettuce (10 microl; 3 x 10(4) CFU/10 g) or onto romaine lettuce plants (20 microl; 3 x 10(6) CFU per leaf). Cut lettuce was sealed in 100-cm2 bags (made from a commercial polymer film) and incubated at 5 or 20 degrees C. Lettuce plants were held at 23 degrees C for 24 h. For all tested conditions, levels of E. coli O157:H7 increased at 20 degrees C on cut lettuce and decreased on cut lettuce stored at 5 degrees C or on leaves of lettuce plants. At 20 degrees C, preinoculation culture conditions had little impact on growth of E. coli O157:H7 on cut lettuce. However, survival at 5 degrees C was significantly better (P lettuce plants was less clear due to relatively high standard deviations observed among samples. PMID:19681285

Theofel, Christopher G; Harris, Linda J

2009-07-01

122

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

123

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

Science.gov (United States)

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

124

Phytoremediation potential of duckweed (Lemna minor L.) in degradation of C.I. Acid Blue 92: artificial neural network modeling.  

Science.gov (United States)

In present study, the potential of duckweed (Lemna minor L.) for degradation of an azo dye C.I. Acid Blue 92 (AB92) has been investigated. The effect of operational parameters such as initial dye concentration, pH, temperature and amount of plant on the efficiency of biological decolorization process was determined. The reusability of Lemna minor L. in long term repetitive operations was also examined. Growth and some biochemical parameters (photosynthetic pigments content, superoxide dismutase, catalase and peroxidase activity) were used to detect the toxic effects of AB92 on duckweed plant. The biological degradation compounds formed in the present process were analyzed by GC-MS technique. In addition, an artificial neural network (ANN) model was expanded to predict the biological decolorization efficiency. The obtained data indicated that ANN provide realistic predictive performance (R(2)=0.954). PMID:22498423

Khataee, A R; Movafeghi, A; Torbati, S; Salehi Lisar, S Y; Zarei, M

2012-06-01

125

Yield of crisphead lettuce under different amounts of irrigation
Produtividade da alface americana submetida a diferentes lâminas de irrigação
 

OpenAIRE

With the aim of minimizing the difficulties faced by the producers on cultivating the crisphead lettuce (Lactuta sativa L), specifically those related to the lack of technical information about the quantity of water to be applied, a study was made in order to determine the effect of various water depths on crisphead lettuce yielding characteristics. The experiment was carried out at the Universidade Federal de Lavras, from October to December 2008 in greenhouse. A randomized block design with...

Joaquim Alves de Lima Junior; Geraldo Magela Pereira; Luciano Oliveira Geisenhoff; Renato Carvalho Vilas Boas; Welligton Gomes da Silva; Andre Luiz Pereira Silva

2012-01-01

126

Accumulation and elimination of lanthanum by duckweed (Lemna minor L.) as influenced by organism growth and lanthanum sorption to glass.  

Science.gov (United States)

Lanthanide emissions to the environment increase as a result of the growing industrial applications of these elements. However, robust data to evaluate the environmental fate of lanthanides are scarce. This article describes the accumulation and elimination of lanthanum (La) by common duckweed (Lemna minor L.). Speciation modeling was performed to assure that solubility products were not exceeded. It also showed that La was predominantly associated with ethylenediaminetetraacetic acid (EDTA). Lanthanum concentrations in plants and medium and the amounts sorbed to glass vessels were quantified by using the radioisotope 140La. The amount of La adsorbed on the glass reached values of 25% of the total La present. A model was formulated to describe La uptake in exponentially growing duckweed in the presence of an adsorptive surface. Growth-induced dilution appeared more efficient in lowering plant La concentrations than actual elimination. An elimination study revealed two compartments, of which the smallest eliminated 50 times faster than the bigger compartment, which eliminated mainly by growth dilution. The average bioconcentration factor was 2,000 L/kg fresh weight and 30,000 L/kg dry weight, comparable with those of other higher plants. At the applied concentration of 10 nM, no effects were observed on duckweed growth. However, the high bioconcentration factor warrants monitoring of lanthanide emissions. PMID:12109750

Weltje, Lennart; Brouwer, Anke H; Verburg, Tona G; Wolterbeek, Hubert Th; de Goeij, Jeroen J M

2002-07-01

127

Nitrate content of lettuce (Lactuca sativa L.) after fertilization with sewage sludge and irrigation with treated wastewater.  

Science.gov (United States)

A romaine-type lettuce (Lactuca sativa L.) was cultivated over three crop seasons (spring 2005, spring 2006 and autumn-winter 2006) in six 36 m(2) plots in Alcázar de San Juan, Spain. A drip irrigation system was used to water all plots: five plots with drinking water and one plot with wastewater from the activated sludge system of a wastewater treatment plant (WWTP). One drinking water-irrigated plot was not fertilized (control). Five different treatments were applied to the soil: three organic mixtures (sewage sludge, sewage sludge mixed with pine bark and municipal solid waste with composted sludge) and a conventional fertilizer were applied to the four plots irrigated with drinking water. The last plot was irrigated with treated wastewater. The treatments were tested for their effect on plant growth and nitrate concentration in vegetable tissue. An increase in fresh weight in the lettuce was linked to the dosage of sewage sludge. The highest nitrate level was observed in the sewage sludge treatment in all crops and seasons, although, in general, all values were below the maximum limits established by the European Commission for nitrate content in fresh romaine lettuce. In the third crop season, a significant increase in nitrate content was observed in lettuce from organic treatments. Nitrate concentration in lettuce from irrigated treated wastewater was higher than control, although significant differences were not found. PMID:19680887

Castro, E; Mañas, M P; De Las Heras, J

2009-02-01

128

Agronomic efficiency of intercropping tomato and lettuce  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Quatro experimentos foram conduzidos na Unesp, Brasil, com o objetivo de determinar a viabilidade agronômica de cultivos consorciados de alface e tomate em ambiente protegido. Consórcios estabelecidos por transplantes da alface aos 0, 10, 20 e 30 dias após o transplante (DAT) do tomate e de tomate a [...] os 0, 10, 20 e 30 DAT da alface, foram avaliados em duas épocas e comparados às suas monoculturas. Cada experimento foi conduzido em delineamento de blocos ao acaso, com nove tratamentos. Verificou-se que a produtividade do tomate e a classificação dos frutos não foram influenciadas pela alface, mas a produção da alface foi menor em consórcio. Quanto mais atrasado o transplante da alface menor foi a sua produtividade. Houve efeito de época de cultivo sobre a dimensão da vantagem agronômica do consórcio sobre a monocultura. Na primeira época de cultivo, os consórcios estabelecidos com o transplante da alface de 30 dias antes e até 20 dias após o transplante do tomate proporcionaram índices de eficiência do uso da área (EUA) de 1,63 a 2,22. Na segunda época, os consórcios estabelecidos com o transplante da alface antes do tomate, em até 30 dias, proporcionaram índices EUA de 1,57 a 2,05. Abstract in english 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 afte [...] r 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.

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

1109-11-01

129

Agronomic efficiency of intercropping tomato and lettuce  

Directory of Open Access Journals (Sweden)

Full Text Available Four experiments were carried out at the São Paulo State University, Brazil, with the aim of determining the agronomic viability of intercropping tomato and lettuce, under greenhouse conditions. The studied intercropping systems were established by transplanting lettuce at 0, 10, 20 and 30 days after transplanting (DAT tomato and by transplanting tomato at 0, 10, 20 and 30 DAT lettuce. Intercropped tomato and lettuce were evaluated during two seasons and compared to their sole cropping. The experimental design was a randomized complete block with nine treatments. The productivity and the classification of the tomato fruits were not influenced by having lettuce intercropped with it, but lettuce production was lowered when tomato was intercropped with it. The longer the delay in lettuce transplanting, the greater the reduction in its productivity. There was an effect of cropping season on the extent of the agronomic advantage of intercropping over sole cropping. In the first cropping season, intercropping established by transplanting lettuce during the interval between 30 days before up to 20 DAT tomato yielded land use efficiency (LUE indices of 1.63 to 2.22. In the second period, intercropping established with the transplanting of lettuce up to 30 days before tomato yielded LUE indices of 1.57 to 2.05.Quatro experimentos foram conduzidos na Unesp, Brasil, com o objetivo de determinar a viabilidade agronômica de cultivos consorciados de alface e tomate em ambiente protegido. Consórcios estabelecidos por transplantes da alface aos 0, 10, 20 e 30 dias após o transplante (DAT do tomate e de tomate aos 0, 10, 20 e 30 DAT da alface, foram avaliados em duas épocas e comparados às suas monoculturas. Cada experimento foi conduzido em delineamento de blocos ao acaso, com nove tratamentos. Verificou-se que a produtividade do tomate e a classificação dos frutos não foram influenciadas pela alface, mas a produção da alface foi menor em consórcio. Quanto mais atrasado o transplante da alface menor foi a sua produtividade. Houve efeito de época de cultivo sobre a dimensão da vantagem agronômica do consórcio sobre a monocultura. Na primeira época de cultivo, os consórcios estabelecidos com o transplante da alface de 30 dias antes e até 20 dias após o transplante do tomate proporcionaram índices de eficiência do uso da área (EUA de 1,63 a 2,22. Na segunda época, os consórcios estabelecidos com o transplante da alface antes do tomate, em até 30 dias, proporcionaram índices EUA de 1,57 a 2,05.

Arthur B. Cecílio Filho

2011-09-01

130

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  

Directory of Open Access Journals (Sweden)

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

Aureo S. de Oliveira

2005-03-01

131

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.

2005-03-01

132

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

133

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-10-15

134

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

OpenAIRE

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, thi...

Maboko, Martin Makgose

2007-01-01

135

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

Directory of Open Access Journals (Sweden)

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

136

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

137

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

DEFF Research Database (Denmark)

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

Jensen, Annette Nygaard; Storm, Christina

2011-01-01

138

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

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

B Nomanpour

2012-04-01

139

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)

140

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

141

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

142

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

143

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

Science.gov (United States)

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

Kittiwongwattana, Chokchai; Thawai, Chitti

2015-01-01

144

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

Science.gov (United States)

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

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

2010-04-15

145

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

Science.gov (United States)

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

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

2015-02-01

146

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

147

Use of Propolis in the Sanitization of Lettuce  

Directory of Open Access Journals (Sweden)

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

148

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

149

Action of different enzymes on germination of lettuce seeds (Lactuca sativa L. - Asteraceae  

Directory of Open Access Journals (Sweden)

Full Text Available Seed germination involves the use of different enzymes for metabolism. The aim of this study was to evaluate theeffect of different commercial enzymes on germination of lettuce seeds. Lettuce seeds were immersed in a solution of300 mL distilled water and 5.0 mL enzyme solution during one hour. The treatments consisted of the commercialenzyme solutions: (1 Alcalase® and Celluclean® (purpose catalyze hydrolysis of peptide bonds and bonds of beta1,3 and 1,4 glucan present in the cellulose, respectively, (2 Pectinex® (purpose dilutes pectin, releasing sugars,(3 Alcalase® (purpose to catalyze peptide bonds, (4 Pectinex® and Alcalase® (purpose to catalyze peptide bondsand to release sugars, (5 Alcalase® and Ban® (purpose to catalyze peptide bonds and hydrolysis of bonds alpha1,4 - glucosidic forming dextrin preferably as product, (6 Spirizyme® (glucoamylase enzyme: glucan 1,4 alphaglucosidaseand (7 control (distilled water free of enzymes. After treatment with the enzyme solutions seeds weresown in Petri dishes containing filter paper or soil as a substrate, both saturated with distilled water. The seeds ofall treatments germinated in four days after seeding. The percentage of seed germination on filter paper showed nosignificant differences between the treatments, but the germination percentage showed statistical differences whengerminated in the soil. The highest percentages of germination in the soil were in the control treatment (96.6% andin the treatment with Pectinex® and Alcalase® (81.6%. Industrial enzymes application in lettuce seeds does notincrease the speed and percentage of seed germination.

Edson Perez Guerra

2012-01-01

150

Growth of lettuce seedlings in different substrates  

OpenAIRE

This research studied the growth of lettuce seedlings (Lactuca sativa L. cv. Veronica) cultivated under greenhouse conditions, using polystyrene trays with 128 cells and three different commercial substrates: Golden Mix, Plantmax and Plugmix. The statistical design was in the form of randomized blocks, with eight (8) replications. Fifteen days after sowing the seeds, samples (five in total) of plants were taken to evaluate the height, number of leaves, leaf area, leaf specific area, leaf spec...

Milene Rodrigues Peres; Carmen Sílvia Fernandes Boaro; Jane Luísa Wadas Lopes; Vandeir Francisco Guimarães

2007-01-01

151

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

152

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)

153

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

Science.gov (United States)

Vegetables can contain significant amounts of nitrate and, therefore, may pose health hazards to consumers by exceeding the accepted daily intake for nitrate. Different hydroponic growing patterns were examined in this work in order to obtain 'nitrate-free lettuces'. Growing lettuces on low nitrate content nutrient solution resulted in a significant decrease in lettuces' nitrate concentrations (1741 versus 39 mg kg(-1)), however the beneficial effect was cancelled out by an increase in the ambient temperature. Nitrate replacement with ammonium was associated with an important decrease of the lettuces' nitrate concentration (from 1896 to 14 mg kg(-1)) and survival rate. An economically feasible method to reduce nitrate concentrations was the removal of all inorganic nitrogen from the nutrient solution before the exponential growth phase. This method led to lettuces almost devoid of nitrate (10 mg kg(-1)). The dried mass and calcinated mass of lettuces, used as markers of lettuces' quality, were not influenced by this treatment, but a small reduction (18%, p nitrate-free' lettuces in an economically feasible way. PMID:25345876

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

2015-01-01

154

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

OpenAIRE

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

Gjesteland, Ingrid

2013-01-01

155

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

156

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

157

Incidence of naturally internalized bacteria in lettuce leaves.  

Science.gov (United States)

Lettuce is the fresh leafy vegetable most frequently involved in foodborne disease outbreaks. Human bacterial pathogens may be experimentally internalized into lettuce plants, but the occurrence of natural microflora inside lettuce leaves has not been elucidated. To characterize the endophytic microorganism residing in commercial lettuce leaves, two separate studies were conducted. First, a total of 30 and 25 heads of romaine and red leaf lettuce, respectively, served as the source of individual leaves which were surface sterilized, stomached, enriched in BHI broth for 24h and plated onto BHI agar for non-selective isolation of internalized microorganism. In a separate survey, 80 heads of each of the two types of lettuce were similarly processed, except that GN broth and MacConkey agar (MCA) were used for isolation of Gram negative bacteria. Thirty-eight out of 100 leaves were positive for internalized microorganisms, and Bacillus, Pseudomonas and Pantoea were the genera most frequently found in both types of lettuce. Members of the genus Erwinia were isolated from romaine lettuce only. In the second study, 21 and 60% of romaine and red leaf lettuce heads, respectively, had internalized bacteria capable of growing on MCA. Among the Gram negative strains, Pseudomonas and Pantoea genera were most frequently isolated. Enterobacter isolates were obtained from three red leaf samples. In summary, spore-forming bacteria and traditional epiphytic bacterial genera were frequently detected in surface-sterilized commercial lettuce leaves. Despite the common occurrence of internalized bacteria, only Enterobacter was related to Escherichia coli O157:H7 and Salmonella. PMID:23454817

Hou, Zhe; Fink, Ryan C; Radtke, Christie; Sadowsky, Michael J; Diez-Gonzalez, Francisco

2013-04-01

158

Whole-leaf wash improves chlorine efficacy for microbial reduction and prevents pathogen cross-contamination during fresh-cut lettuce processing.  

Science.gov (United States)

Currently, most fresh-cut processing facilities in the United States use chlorinated water or other sanitizer solutions for microbial reduction after lettuce is cut. Freshly cut lettuce releases significant amounts of organic matter that negatively impacts the effectiveness of chlorine or other sanitizers for microbial reduction. The objective of this study is to evaluate whether a sanitizer wash before cutting improves microbial reduction efficacy compared to a traditional postcutting sanitizer wash. Romaine lettuce leaves were quantitatively inoculated with E. coli O157:H7 strains and washed in chlorinated water before or after cutting, and E. coli O157:H7 cells that survived the washing process were enumerated to determine the effectiveness of microbial reduction for the 2 cutting and washing sequences. Whole-leaf washing in chlorinated water improved pathogen reduction by approximately 1 log unit over traditional cut-leaf sanitization. Similar improvement in the reduction of background microflora was also observed. Inoculated "Lollo Rossa" red lettuce leaves were mixed with noninoculated Green-Leaf lettuce leaves to evaluate pathogen cross-contamination during processing. High level (96.7% subsamples, average MPN 0.6 log CFU/g) of cross-contamination of noninoculated green leaves by inoculated red leaves was observed when mixed lettuce leaves were cut prior to washing in chlorinated water. In contrast, cross-contamination of noninoculated green leaves was significantly reduced (3.3% of subsamples, average MPN water before cutting. This result suggests that whole-leaf sanitizing washes could be a practical strategy for enhancing the efficacy of chlorine washes for pathogen reduction and cross-contamination prevention. PMID:20629885

Nou, Xiangwu; Luo, Yaguang

2010-06-01

159

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  

OpenAIRE

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

160

Thermolysis of microalgae and duckweed in a CO?-swept fixed-bed reactor: bio-oil yield and compositional effects.  

Science.gov (United States)

Microalgae and duckweed were grown and harvested over a three-month period in CO(2)-sparged helioreactors and open earthen ponds, respectively. The biomass feedstocks were thermolyzed in a thermogravimetric analyzer (TGA) and fixed-bed reactor to produce a fuel precursor coined "bioleum". Analysis of the thermolysis kinetics revealed an increase in the activation energy with heating rate for both aquatic species. Activation energies were lower than literature-reported values for lignocellulosics, corroborated by TGA thermolysis of pinewood. Thermolysis of microalgae resulted in higher bioleum and energy yields than for duckweed, reflecting differences in the biomass composition. The algal bioleum properties resemble those of crude petroleum except for higher nitrogen and oxygen content and acid number. Speciation identified 300+ compounds in the oil phase, with similar amounts of hydrocarbons and oxygenates, while acetic acid was the major species in the aqueous phase. The compounds were classified according to their degree of aromaticity, oxygenation, and nitrogenation. PMID:22285294

Campanella, Alejandrina; Muncrief, Rachel; Harold, Michael P; Griffith, David C; Whitton, Norman M; Weber, Robert S

2012-04-01

161

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.

1503-15-01

162

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  

Directory of Open Access Journals (Sweden)

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

163

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

Science.gov (United States)

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

Kutschera, U; Niklas, K J

2015-01-01

164

Tobacco streak virus Isolated from Lettuce  

Directory of Open Access Journals (Sweden)

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

165

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

OpenAIRE

Noroviruses are the leading cause of food-borne outbreaks, including those that involve lettuce. The culturable porcine sapovirus (SaV) was used as a norovirus surrogate to study the persistence and the potential transfer of the virus from roots to leaves and from outer to inner leaves of lettuce plants. Treatment of lettuce with SaV was done through the roots of young plants, the soil, or the outer leaves of mature plants. Sampling of roots, xylem sap, and inner and outer leaves followed by ...

Esseili, Malak A.; Wang, Qiuhong; Zhang, Zhenwen; Saif, Linda J.

2012-01-01

166

Simulación computacional del crecimiento de la población de Lemna sp en el Lago de Maracaibo / Computational simulation of duckweed population growth rate in Lake Maracaibo  

Scientific Electronic Library Online (English)

Full Text Available SciELO Venezuela | Language: Spanish Abstract in spanish El presente trabajo tiene como finalidad determinar las áreas de mayor reproducción de Lemna sp en el Lago de Maracaibo, incorporando en el modelo hidrodinámico MIKE 3 un modelo matemático que estima la tasa de crecimiento de Lemna sp considerando los parámetros que influyen en la misma. El modelo m [...] atemático propuesto es desarrollado a partir de un estudio previo sobre modelaje de crecimiento de Lemna en función del nitrógeno, realizado por Landesman, afectado adicionalmente por los parámetros fósforo, salinidad y temperatura. Luego de ajustar el modelo matemático a las condiciones del Lago es introducido al modelo computacional hidrodinámico para simular el crecimiento de Lemna sp en los meses de enero a noviembre; etapa que abarca los períodos seco y lluvioso característicos de la zona. Los resultados de las simulaciones son comparados con imágenes del satélite MODIS, obteniéndose coincidencias en las zonas de mayor crecimiento de Lemna sp. También se realiza un análisis mes a mes de los resultados, encontrando diferencias entre los períodos seco y lluvioso; con un aumento del potencial de crecimiento de Lemna sp en el período lluvioso tanto en la bolsa del Lago como en el estrecho de Maracaibo. Abstract in english The present work has the purpose of determining the zones of highest growth rate of Lemna sp (duckweed) in Lake Maracaibo using a hydrodynamic circulation model (MIKE 3), and a mathematical model to estimate the rate of growth of this aquatic plant. The proposed mathematical model is developed start [...] ing from a study on modeling duckweed growth as a function of nitrogen carried out by Landesman, affected additionally by phosphorus, salinity and temperature parameters. After fitting the mathematical model to lake conditions, it is introduced to the computational hydrodynamic model to simulate growth of duckweed from january to november, which comprises a dry and a rainy season, characteristic of the area. The results of the simulations are compared with images of the lake from the MODIS the satellite, showing similarities in the areas of higher growth of duckweed. Also an analysis month by month of the results is carried out, finding differences among the dry and rainy seasons; with an increase of the potential of growth of duckweed towards the rainy season in the Lake as well as in the strait of Maracaibo.

Gustavo, Badell; Janett, Flores; José, Rincón; María, Rubio.

2008-12-01

167

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

Science.gov (United States)

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

Keskinen, Lindsey A; Annous, Bassam A

2011-06-30

168

Nitrogenase Activity of Pseudomonas corrugata Isolated from Egyptian Lettuce  

Directory of Open Access Journals (Sweden)

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

169

Relationship between Soil Health Assessment and the Growth of Lettuce  

Directory of Open Access Journals (Sweden)

Full Text Available Soil health is very important point for plant growth which is measured by several indicators. The purposes of the research were to assess and to classify soil health Padang Betuah area of Bengkulu, and to compare between soil health indicators and lettuce plant performance indicators. Soils, consist of mineral and peat soils, were sampled using a soil random sampling technique. Lettuce plants were grown in polybags using sample soils. Both lettuce performance and soil health were assessed by calculating the percentage of total scores of lettuce plant or soil performance indicators which derived from variables observed. Soil variables for field evaluation included color, moisture content, texture, structure, compaction, land slope, organic matter, pH, amount of earthworm, erosion level, LCC (Legume Cover Crop, and vegetation performance. Soil variables for laboratory evaluation were pH, electrical conductivity (EC, total Carbon and Nitrogen, available-Posphorus, cation exchangeable capacity, base saturation, and aluminum saturation. While, the variables for lettuce growth performance included plant height, numbers of leaf, degree of leaf greenness, plant fresh weight, and relative percentage of shoot : root ratio. The results of field and laboratory evaluation showed that soil health were categoried as a healthy soil and moderate healthy soil both for mineral and peat soils, respectively. Furthermore, similar categories were also obtained for evaluation of plant performance categories. No correlation was found between the soil performance indicator category and the lettuce performance category.

Merakati Handajaningsih

2011-01-01

170

Growth of lettuce seedlings in different substrates  

Directory of Open Access Journals (Sweden)

Full Text Available This research studied the growth of lettuce seedlings (Lactuca sativa L. cv. Veronica cultivated under greenhouse conditions, using polystyrene trays with 128 cells and three different commercial substrates: Golden Mix, Plantmax and Plugmix. The statistical design was in the form of randomized blocks, with eight (8 replications. Fifteen days after sowing the seeds, samples (five in total of plants were taken to evaluate the height, number of leaves, leaf area, leaf specific area, leaf specific weight, absolute and relative growth rates and net assimilation rates. The evaluated growth indexes showed that seedlings produced with the Plantmax and Plugmix substrates could be planted 25 days after sowing, since they have at least four definitive leaves. The Plantmax substrate showed, at the end of the evaluation, the best results in height, dry weight, leaf specific area, absolute growth rates and net assimilation rates.

Milene Rodrigues Peres

2007-12-01

171

Comparative study of substrate-based and commercial formulations of arbuscular mycorrhizal fungi in Romaine lettuce subjected to salt stress  

OpenAIRE

To compare the effect of substrate-based and commercial arbuscular mycorrhizal fungi (AMF) in salt stress tolerance of Romaine lettuce a bifactorial analysis was carried out. Under non-saline conditions, only plants inoculated with formulation 1 stimulated shoot weight but not related with greater root AMF colonization. Phosphorus and potassium concentrations in leaves were improved by mycorrhizal association. Irrigation with 100 mM sodium chloride (NaCl) did not affect leaf relative water co...

Garmendia Lo?pez, Idoia; Mangas Marti?n, Vi?ctor Javier

2014-01-01

172

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

OpenAIRE

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

173

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

Directory of Open Access Journals (Sweden)

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

174

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

OpenAIRE

Fresh produce is a major vehicle for the transmission of human norovirus (NoV) because it is easily contaminated during both pre- and postharvest stages. However, the ecology of human NoV in fresh produce is poorly understood. In this study, we determined whether human NoV and its surrogates can be internalized via roots and disseminated to edible portions of the plant. The roots of romaine lettuce growing in hydroponic feed water were inoculated with 1 × 106 RNA copies/ml of a human NoV gen...

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

2012-01-01

175

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

176

Crisphead lettuce (lactuca sativa l.) cultivar evaluation and response of transplants to nitrogen nutrition  

OpenAIRE

Experiments were conducted with lettuce at the field and in the glasshouse at the Hatfield Experimental Farm, University of Pretoria. The objectives of the study were to evaluate the performance of selected crisphead lettuce cultivars in relation to yield and quality performance and to investigate which level of nitrogen can produce high quality transplants. In the lettuce cultivar trial, fifteen crisphead lettuce cultivars were grown, during March to May 2004. The experiment was laid out as ...

Madzivhandila, Livhuwani Lilly-rose

2005-01-01

177

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

OpenAIRE

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

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

2012-01-01

178

Classification of Lettuce Nitrogen Levels Based on Image Feature Extraction and Optimization  

OpenAIRE

The feature extraction and optimization of lettuce leaf image are the important premise of classification recognition of lettuce nitrogen levels. The lettuce samples of different nitrogen levels were cultivated in soilless cultivation using nitrogen nutrition of different concentrations. When the lettuce leaf images were collected, image features have been extracted, including texture features, shape features and color features. Because of the redundancy of characteristic values, there were i...

Sun Jun; Jiang Shuying; Mao Hanping; Zhang Xiaodong; Zhu Wenjing; Wang Yan

2013-01-01

179

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

International Nuclear Information System (INIS)

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

180

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

Scientific Electronic Library Online (English)

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

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

2014-08-01

181

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

182

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

OpenAIRE

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...

Ana Beatriz Almeida de Oliveira; Ana Carolina Ritter; Eduardo Cesar Tondo; Marisa de Itapema Cardoso

2012-01-01

183

Comparison of Different Washing and Disinfection Protocols Used by Food Services in Southern Brazil for Lettuce (<i>Lactuca sativa</i>)  

OpenAIRE

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...

Ana Beatriz Almeida de Oliveira; Ana Carolina Ritter; Eduardo Cesar Tondo; Marisa de Itapema Cardoso

2012-01-01

184

Development of molecular markers for marker-assisted selection in lettuce (Lactuca sativa).  

Science.gov (United States)

Lettuce dieback disease is widespread in commercially grown romaine and leaf-type lettuces, but not in iceberg-type cultivars. The cause of disease are two closely related tombusviruses -- Tomato bushy stunt virus (TBSV) and Lettuce necrotic stunt virus (LNSV). A single dominant gene on chromosome 2...

185

RELATIONSHIP BETWEEN THE NUTRITIONAL VALUE AND THE HEAD STRUCTURE OF LETTUCE  

Science.gov (United States)

Crisphead lettuce has much lower vitamin A, vitamin C, calcium, and iron contents than leaf or romaine lettuce. This experiment was conducted to determine whether the low nutritional value is associated with the head structure. Heads of a crisphead lettuce cultivar 'Salinas' grown in the field were ...

186

RELATIONSHIP BETWEEN THE NUTRIONAL VALUE AND THE HEAD STRUCTURE OF LETTUCE  

Science.gov (United States)

Crisphead lettuce has much lower vitamin A, vitamin C, calcium, and iron contents than leaf or romaine lettuce. This experiment was conducted to determine whether the low nutritional value is associated with the head structure. Heads of a crisphead lettuce cultivar "Salinas" grown in the field were ...

187

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

Science.gov (United States)

...2010-01-01 false Lettuce and peppers from Israel. 319.56-24 Section 319.56-24...319.56-24 Lettuce and peppers from Israel. (a) Lettuce may be imported into the United States from Israel without fumigation for leafminers,...

2010-01-01

188

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

Science.gov (United States)

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

189

Rapid determination of fosetyl-aluminum residues in lettuce by liquid chromatography/electrospray tandem mass spectrometry.  

Science.gov (United States)

This paper describes a new method for the sensitive and selective determination of fosetyl-aluminum (Al) residues in vegetable samples. The method involves extraction with water by using a high-speed blender and subsequent injection of the 5-fold diluted extract into the liquid chromatograph. Fosetyl-Al is determined by liquid chromatography with electrospray tandem mass spectrometry after the addition of tetrabutylammonium acetate as the ion-pairing reagent. The method has been used to assay lettuce samples spiked at 2 and 0.2 mg/kg. Recoveries were satisfactory, with mean values of 98 and 106%, respectively, and relative standard deviations were fosetyl-Al residues in lettuce with very little sample handling and good sensitivity; it was shown to be robust by the analysis of almost 100 samples. PMID:14509444

Hernández, Félix; Sancho, Juan V; Pozo, Oscar J; Villaplana, Carme; Ibáñez, María; Grimalt, Susana

2003-01-01

190

Pilot-scale comparison of four duckweed strains from different genera for potential application in nutrient recovery from wastewater and valuable biomass production.  

Science.gov (United States)

The application potential of four duckweed strains from four genera, Wolffia globosa 0222, Lemna japonica 0223, Landoltia punctata 0224 and Spirodela polyrhiza 0225, were compared in four parallel pilot-scale wastewater treatment systems for more than 1 year. The results indicated that each duckweed strain had unique potential advantages. Unlike L. japonica 0223 and La. punctata 0224, which grow throughout the year, S. polyrhiza 0225 and W. globosa 0222 do not survive cold weather. For year round performance, L. japonica 0223 was best not only in dry biomass production (6.10 g·m(-2) ·day(-1) ), but also in crude protein (35.50%), total amino acid (26.83%) and phosphorus (1.38%) content, plus recovery rates of total nitrogen (TN), total phosphorus (TP) and CO2 (0.31, 0.085 and 7.76 g·m(-2) ·day(-1) , respectively) and removal rates of TN and TP (0.66 and 0.089 g·m(-2) ·day(-1) , respectively). This strongly demonstrates that L. japonica 0223 performed best in wastewater treatment and protein biomass production. Under nutrient starvation conditions, La. punctata 0224 had the highest starch content (45.84%), dry biomass production (4.81 g·m(-2) ·day(-1) ) and starch accumulation (2.9 g·m(-2) ·day(-1) ), making it best for starch biomass production. W. globosa 0222 and S. polyrhiza 0225 showed increased flavonoid biomass production, with higher total flavonoid content (5.85% and 4.22%, respectively) and high dominant flavonoids (>60%). This study provides useful information for selecting the appropriate local duckweed strains for further application in wastewater treatment and valuable biomass production. PMID:24942851

Zhao, Y; Fang, Y; Jin, Y; Huang, J; Bao, S; Fu, T; He, Z; Wang, F; Wang, M; Zhao, H

2015-01-01

191

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

192

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

193

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

OpenAIRE

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 so...

Boyer, Ce?cile

2009-01-01

194

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

Science.gov (United States)

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

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

2012-02-01

195

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

Science.gov (United States)

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

196

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

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Full Text Available Hydroponic production of vegetables is becoming more common. In this study hydroponic lettuce, grown by a local distributor, and conventionally and organically field-grown lettuce, purchased at local retail stores were compared by descriptive analysis for taste, odor, visual quality and texture. Five lettuce varieties were compared; Romaine, Green Leaf, Red Leaf, Butter, and Common lettuce. A twenty-three member sensory panel randomly rated the lettuce using a 5 point scale or a 3 point scale for taste, odor, visual quality and texture. Analysis of variance (ANOVA was performed for each lettuce variety with comparison between those hydroponically, organically or conventionally grown. Overall, panel members equally like the different lettuce samples. The results showed that for each of the five varieties of let-tuces, all lettuces were perceived to be equal in their sensory evaluation for locally grown hydroponic lettuce or pur-chased from local grocery outlets as organically or conventionally grown.

Yukiko K. Nakamura

2011-04-01

197

Secondary metabolism and antioxidants are involved in environmental adaptation and stress tolerance in lettuce.  

Science.gov (United States)

Lettuce (Lactuca sativa) plants grown in a protective environment, similar to in vitro conditions, were acclimated in a growth chamber and subjected to water stress to examine the activation of genes involved in secondary metabolism and biosynthesis of antioxidants. The expression of phenylalanine ammonia-lyase (PAL), gamma-tocopherol methyl transferase (gamma-TMT) and l-galactose dehydrogenase (l-GalDH) genes involved in the biosynthesis of phenolic compounds, alpha-tocopherol and ascorbic acid, respectively, were determined during plant adaptation. These genes were activated in tender plants, grown under protective conditions, when exposed to normal growing conditions in a growth chamber. A large increase in transcript level for PAL, a key gene in the phenylpropanoid pathway leading to the biosynthesis of a wide array of phenolics and flavonoids, was observed within 1h of exposure of tender plants to normal growing conditions. Plant growth, especially the roots, was retarded in tender plants when exposed to normal growing conditions. Furthermore, exposure of both protected and unprotected plants to water stress resulted in the activation of PAL. PAL inhibition by 2-aminoindan-2-phosphonic acid (AIP) rendered these plants more sensitive to chilling and heat shock treatments. These results suggest that activation of secondary metabolism as well as the antioxidative metabolism is an integral part of plant adaptation to normal growing conditions in lettuce plants. PMID:18562042

Oh, Myung-Min; Trick, Harold N; Rajashekar, C B

2009-01-30

198

Plant growth, metabolism and adaptation in relation to stress conditions. XXI. Reversal of harmful NaCl-effects in lettuce plants by foliar application with urea  

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Full Text Available In relation to water control levels, administration of NaCl at low (3 dSm-1, medium (5 dSm-1 or high (7 dSm-1 concentration, in the growth medium of the lettuce plants, induced significant decreases in growth components as well as in the metabolites and enzymes determined, at vegetative and adult growth stages. On the other hand, significant increases in all growth and photosynthetic components determined, as well as in carbohydrate contents and in the activities of the antioxidant enzymes were obtained, above the water control levels, in response of treatment of lettuce plants with urea fertilizer up to 4 %, above which urea at 5% and 6% induced significant decreases in all the above mentioned components, throughout the entire periods of the experiments. Foliar application of urea up to 5 % to the variously salinized lettuce plants induced significant increases in all growth components as well as in all metabolites determined as compared with values of control-salinized plants. At 6% urea, significant decreases in growth parameters and in metabolites determined for the variously salinized plants were apparent. Thus, foliar application of urea can, at least, partially alleviate the inhibitory effects of salinity on growth and metabolism of lettuce plants; the magnitude of response being most pronounced with 3-4% urea.

Mahmoud Elbaz Younis

2008-09-01

199

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

OpenAIRE

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

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

2011-01-01

200

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

OpenAIRE

Lettuce, spinach and chicory are generally considered the main leafy vegetables, while a fourth group denoted by ‘minor leafy vegetables’ includes, amongst others, rocket salad, lamb’s lettuce, asparagus, artichoke and rhubarb. Except in the case of lettuce, central crop databases of leafy vegetables were lacking until recently. Here we report on the update of the international Lactuca database and the development of three new central crop databases for each of the other leafy vegetable...

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

2012-01-01

201

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

OpenAIRE

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...

Leela Kaur; Kasturi Gadgil; Satyawati Sharma

2012-01-01

202

Hygienic-sanitary quality of vegetables and evaluation of treatments for the elimination of indigenous E. coli and E. coli O157:H7 from the surface of leaves of lettuce (Lactuca sativa L.) Qualidade higiênico-sanitária de hortaliças e avaliação de tratamentos para eliminação de E. coli indígena e E. coli O157:H7 na superfície de folhas de alface (Lactuca sativa L.)  

OpenAIRE

The purpose of this study is to evaluate the hygienic-sanitary quality of vegetables and irrigation water and assess the effectiveness of lemon juice and vinegar in reducing E. coli strains inoculated on lettuce. One hundred and forty samples of vegetables and 45 samples of irrigation water were investigated for thermotolerant coliforms and Salmonella spp. In order to verify the effectiveness of natural household sanitizers in reducing E. coli in inoculated lettuce, four treatment solutions w...

Ytana oliveira Santos; Rogeria Comastri de Castro Almeida; Alaise Gil Guimarães; Paulo Fernando de Almeida

2010-01-01

203

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  

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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

204

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

205

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

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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...

206

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

Science.gov (United States)

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

207

Indexação do Lettuce mosaic virus em sementes e plântulas de genótipos de alface Lettuce mosaic virus indexation in seeds and seedlings of lettuce genotypes  

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Full Text Available O Lettuce mosaic virus espécie mais importante na cultura de alface (Lactuca sativa L. no Brasil, causando sintomas de mosaico, clareamento das nervuras, necrose, distorção foliar e redução do crescimento da planta, pode ser transmitido por sementes com uma taxa de 1% a 16%, dependendo da interação dos genótipos de alface com os isolados LMV-Most ou LMV-Common. Neste trabalho, avaliou-se a detecção do LMV por PTA-ELISA, em sementes e plântulas de oito genótipos de alface: 'Vanessa Roxa', 'Baba de Verão', 'Verdinha', 'Maravilha das 4 Estações', 'Evely', 'Marcela', 687 ('Sapore' x 'Vera' , 784 ('Sapore' x 'Vera', utilizando anti-soro policlonal específico. O vírus não foi detectado em sementes do genótipo 'Verdinha' e, em plântulas dos genótipos 687, 'Marcela' e 'Evely', após a germinação em papel e 687, 784 e 'Marcela' com gene mo1¹, após a germinação em substrato. A avaliação individual do número de sementes infectadas foi de 100% para 'Vanessa Roxa' e 'Baba de Verão', 87,7% para 'Verdinha', 46,6% para 'Maravilha das 4 Estações' e 16,6% para 'Evely'. Nos genótipos com gene de resistência o percentual foi de 15,6%, 26,6%, 90% em 'Marcela', 687 e 784, respectivamente. A detecção do LMV por PTA-ELISA foi eficiente tanto em sementes quanto em plântulas.Lettuce mosaic virus is the major virus in lettuce (Lactuca sativa L. in Brazil, causing symptoms of mosaic, vein clearing, necrosis, leaf distortion and growth reduction. The LMV is transmitted by seeds at a rate of 1% to 16%, mostly due to interaction between the isolates LMV-Most and LMV-Common and the lettuce cultivar. In this study, LMV detection by PTA-ELISA in seeds and seedlings of eight lettuce genotypes, 'Vanessa Roxa', 'Baba de Verão', 'Verdinha', 'Maravilha das 4 Estações', 'Evely', 'Marcela', 687 ('Vera' X 'Sapore', 784 ('Vera' X 'Sapore', was evaluated, using specific polyclonal antisera. The virus was not detected in seeds of 'Verdinha' genotype and seedlings of 687, 'Marcela' and 'Evely' after germination in a paper towel or in 687, 784 and 'Marcela' with the mo1¹ resistance gene, after germination in a substrate. The individual evaluation of the number of infected seeds made by PTA-ELISA was 100% for 'Vanessa Roxa' and 'Baba de Verão', 87.7% for 'Verdinha', 46.6% for 'Maravilha das 4 Estações' and 16.6% for 'Evely'. In the genotypes with the resistance gene the percentage was 15.6%, 26.6%, 90% in 'Marcela', 687 and 784, respectively. Virus detection in seeds and seedlings by PTA-ELISA was very efficient for both seeds and seedlings.

Lillian Silveira Pereira

2012-01-01

208

Effects of seasonal variation on sensory properties and total phenolic content of 5 lettuce cultivars.  

Science.gov (United States)

Butterhead, crisphead, green leaf, red leaf, and romaine types of lettuce (Lactuca sativa L.) are all commonly available in U.S. markets. Sensory properties of lettuce may vary in response to environmental factors that often fluctuate widely throughout the growing season. Bitterness is generally thought to increase in lettuce grown at higher temperatures and may be related to phenolic content. This study evaluated sensory properties and total phenolic content of 5 lettuce cultivars harvested early, midway, and late in the growing season and investigated possible correlations with environmental temperature and light intensity indexes. Thirty panelists rated bitterness, appearance, flavor, texture, and overall acceptability of "Crisp and Green" (green leaf), "Crispino" (crisphead), "Green Forest" (romaine), "Lochness" (butterhead), and "Vulcan" (red leaf) lettuce. There was considerable variation in sensory ratings among the 5 cultivars (P lettuce cultivars appear to have a larger impact on sensory and phenolic profiles than environmental variation during the growing season. PMID:20492312

Bunning, Marisa L; Kendall, Patricia A; Stone, Martha B; Stonaker, Frank H; Stushnoff, Cecil

2010-04-01

209

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

Science.gov (United States)

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and 125 ng/g fresh weight, respectively. Antimicrobial concentrations in lettuce decreased from the first to the third harvest suggesting that the plant growth rate may exceed antimicrobial uptake rates. Accumulation of antimicrobials was significantly different between cultivars demonstrating a subspecies level variation in uptake of antibiotics in lettuce. PMID:25483595

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

2015-02-01

210

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

211

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

OpenAIRE

Large genotypic variation in shoot Cd concentrations has been reported in literature for several plant species including lettuce ( Lactuca sativa L.) and maize ( Zea mays L.). The objective of this thesis was to elucidate the physiological andlor morphological basis of this differential behaviour using lettuce and maize as test plants.Lettuce varieties were grown on soil and on nutrient solution culture with or without Cd. In contrast to published data, the genotypic variation in Cd uptake an...

Florijn, P. J.

1993-01-01

212

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 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

213

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

214

Environmental stresses induce health-promoting phytochemicals in lettuce.  

Science.gov (United States)

Plants typically respond to environmental stresses by inducing antioxidants as a defense mechanism. As a number of these are also phytochemicals with health-promoting qualities in the human diet, we have used mild environmental stresses to enhance the phytochemical content of lettuce, a common leafy vegetable. Five-week-old lettuce (Lactuca sativa L.) plants grown in growth chambers were exposed to mild stresses such as heat shock (40 degrees C for 10 min), chilling (4 degrees C for 1d) or high light intensity (800 micromolm(-2)s(-1) for 1d). In response to these stresses, there was a two to threefold increase in the total phenolic content and a significant increase in the antioxidant capacity. The concentrations of two major phenolic compounds in lettuce, chicoric acid and chlorogenic acid, increased significantly in response to all the stresses. Quercetin-3-O-glucoside and luteolin-7-O-glucoside were not detected in the control plants, but showed marked accumulations following the stress treatments. The results suggest that certain phenolic compounds can be induced in lettuce by environmental stresses. Of all the stress treatments, high light produced the greatest accumulation of phenolic compounds, especially following the stress treatments during the recovery. In addition, key genes such as phenylalanine ammonia-lyase (PAL), l-galactose dehydrogenase (l-GalDH), and gamma-tocopherol methyltransferase (gamma-TMT) involved in the biosynthesis of phenolic compounds, ascorbic acid, and alpha-tocopherol, respectively, were rapidly activated by chilling stress while heat shock and high light did not appear to have an effect on the expression of PAL and gamma-TMT. However, l-GalDH was consistently activated in response to all the stresses. The results also show that these mild environmental stresses had no adverse effects on the overall growth of lettuce, suggesting that it is possible to use mild environmental stresses to successfully improve the phytochemical content and hence the health-promoting quality of lettuce with little or no adverse effect on its growth or yield. PMID:19297184

Oh, Myung-Min; Carey, Edward E; Rajashekar, C B

2009-07-01

215

Hypochlorite treatments are not a significant source of perchlorate exposure in lettuce.  

Science.gov (United States)

Leafy vegetables, such as lettuce ( Lactuca sativa L), have been identified as a potential source of perchlorate exposure to humans. Perchlorate is of concern because excessive amounts may impair thyroid function by inhibiting iodide uptake by the sodium iodide symporter. Perchlorate has been identified as an oxidation product in sodium hypochlorite. Dilute hypochlorite solutions are widely used on lettuce as a preservative and as a treatment to reduce microbial food risks. However, the potential of hypochlorite to be a source of human perchlorate exposure from lettuce had not been evaluated. Studies were conducted with lettuce collected in the San Luis Valley of southern Colorado and in the lower Colorado River Valley of southwestern Arizona to represent conditions under which hypochlorite is applied to lettuce in the field and in salad processing facilities. We used spray and dipping solutions that were dilutions of concentrated sodium hypochlorite that would contain from 12000 and 120000 microg/L perchlorate. The perchlorate content of iceberg and romaine lettuce averaged 6.2 and 7.2 microg/kg fw in southern Colorado and 14.0 and 56.7 microg/kg fw in southwestern Arizona and there were no significant (P > 0.05) increases in the perchlorate content of lettuce due to hypochlorite treatments. Because of the relatively low concentrations of perchlorate present after dilution and the low volumes applied to lettuce, hypochlorite solutions do not appear to be a significant source of the perchlorate levels found in lettuce. PMID:19245207

Sanchez, C A; Fonseca, J M; Blount, B C; Krieger, R I

2009-03-25

216

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

Directory of Open Access Journals (Sweden)

Full Text Available Effect of three-dimension fertilizing mode (3-DFM using CO2 and liquid/solid fractions of the digesate from anaerobic digester was investigated in quality and yield of lettuce. CO2, solid fraction of digestate (SFD, and liquid fraction of digestate (LFD were used as fertilizer for gaseous fertilizer, the base fertilizer, and foliar fertilizer, respectively. The result showed that the 3-DFM was appropriate for lettuce. Lettuce’s plant height, width and number of leaves growth amount were 29.25 cm, 22.38 cm, and 16.2 cm, which were 26.8%, 16.5%, and 18.4% higher than the control, respectively. The overall yield of lettuce was 30.78% more than that of the control. The soluble sugar content and the chlorophyll content in lettuce was the highest, which were 29.4% and 11.4% higher than the control. Under the CO2 and SFD condition, the content of vitamin C in lettuce, the content of free amino acid, crude protein and crude fiber contents of lettuce were the highest. The experimental study can provide an effective way to improve yield and quality of lettuce and utilize biogas plants wastes.

Hairong Yuan

2014-06-01

217

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

OpenAIRE

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

218

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

Science.gov (United States)

...section. APHIS received a request from the Government of Egypt to allow the importation of fresh shredded lettuce (Lactuca sativa L.) from Egypt into the continental United States. Currently, fresh shredded lettuce is not authorized for...

2011-08-17

219

Distribution of Salmonella typhimurium in romaine lettuce leaves.  

Science.gov (United States)

Leafy greens are occasionally involved in outbreaks of enteric pathogens. In order to control the plant contamination it is necessary to understand the factors that influence enteric pathogen-plant interactions. Attachment of Salmonella enterica serovar typhimurium to lettuce leaves has been demonstrated before; however, only limited information is available regarding the localization and distribution of immigrant Salmonella on the leaf surface. To extend our knowledge regarding initial pathogen-leaf interactions, the distribution of green-fluorescent protein-labeled Salmonella typhimurium on artificially contaminated romaine lettuce leaves was analyzed. We demonstrate that attachment of Salmonella to different leaf regions is highly variable; yet a higher attachment level was observed on leaf regions localized close to the petiole (7.7 log CFU g(-1)) compared to surfaces at the far-end region of the leaf blade (6.2 log CFU g(-1)). Attachment to surfaces located at a central leaf region demonstrated intermediate attachment level (7.0 log CFU g(-1)). Salmonella displayed higher affinity toward the abaxial side compared to the adaxial side of the same leaf region. Rarely, Salmonella cells were also visualized underneath stomata within the parenchymal tissue, supporting the notion that this pathogen can also internalize romaine lettuce leaves. Comparison of attachment to leaves of different ages showed that Salmonella displayed higher affinity to older compared to younger leaves (1.5 log). Scanning electron microscopy revealed a more complex topography on the surface of older leaves, as well as on the abaxial side of the examined leaf tissue supporting the notion that a higher attachment level might be correlated with a more composite leaf landscape. Our findings indicate that initial attachment of Salmonella to romaine lettuce leaf depends on multiple plant factors pertaining to the specific localization on the leaf tissue and to the developmental stage of the leaf. PMID:21569943

Kroupitski, Yulia; Pinto, Riky; Belausov, Eduard; Sela, Shlomo

2011-08-01

220

Organic Crop Management Enhances Chicoric Acid Content in Lettuce  

OpenAIRE

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

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

2012-01-01

221

Comparison of three fungicide spray advisories for lettuce downy mildew  

OpenAIRE

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

222

Heat and drought stress during growth of lettuce (Lactuca sativa L.) does not promote internalization of Escherichia coli O157:H7.  

Science.gov (United States)

Studies were done to determine the effect of heat stress on internalization of Escherichia coli O157:H7 in lettuce subjected to different watering practices during growth. Iceberg and romaine lettuce were grown in sandy soil in an environmental chamber at 23 degrees C during the day and 7 degrees C at night, with a 12-h photoperiod. Thirty days after transplanting seedlings, potting soil was inoculated with a five-strain mixture of green fluorescent protein-labeled E. coli O157:H7 at populations of 4 and 6 log CFU/g of soil. Lettuce plants were exposed to one of two temperature stress regimes: 36 degrees C during the day and 15 degrees C at night for 2 days, or 32 degrees C during the day and 15 degrees C at night for 3 days, both with a 12-h photoperiod. Control plants were held at 23 degrees C during the day and 7 degrees C at night for 3 days. Plants were either watered daily or not watered during the heat stress and control treatments. E. coli O157:H7 was detected by enrichment in all inoculated soil and rhizosphere samples from plants grown in inoculated soil. Less E. coli O157:H7 was detected in inoculated heat-stressed soil than in control soil. From inoculated pots, all leaf surfaces and macerated leaves that had been surface sanitized were negative for E. coli O157:H7. All surface-sanitized macerated roots from control samples and from 143 of 144 samples of inoculated samples were negative for E. coli O157:H7. Heat stress during growth of lettuce did not promote or enhance internalization of E. coli O157:H7, regardless of the moisture content in the soil. PMID:20003727

Zhang, Guodong; Ma, Li; Beuchat, Larry R; Erickson, Marilyn C; Phelan, Vanessa H; Doyle, Michael P

2009-12-01

223

Internalization of sapovirus, a surrogate for norovirus, in romaine lettuce and the effect of lettuce latex on virus infectivity.  

Science.gov (United States)

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

Esseili, Malak A; Wang, Qiuhong; Zhang, Zhenwen; Saif, Linda J

2012-09-01

224

Persistence and dissipation of chlorpyrifos in Brassica chinensis, lettuce, celery, asparagus lettuce, eggplant, and pepper in a greenhouse.  

Science.gov (United States)

The residue behavior of chlorpyrifos, which is one of the extensively used insecticides all around the world, in six vegetable crops was assessed under greenhouse conditions. Each of the vegetables was subjected to a foliar treatment with chlorpyrifos. Two analytical methods were developed using gas chromatography equipped with a micro-ECD detector (LOQ?=?0.05 mg kg(-1)) and liquid chromatography with a tandem mass spectrometry (LOQ?=?0.01 mg kg(-1)). The initial foliar deposited concentration of chlorpyrifos (mg kg(-1)) on the six vegetables followed the increasing order of brassica chinensisasparagus lettuceasparagus lettuce), and 3.50 mg kg(-1) (celery), respectively. The half-lives of chlorpyrifos were found to be 7.79 (soil), 2.64 (pepper plants), 3.90 (asparagus lettuce), 3.92 (lettuce), 5.81 (brassica chinensis), 3.00 (eggplant plant), and 5.45 days (celery), respectively. The dissipation of chlorpyrifos in soil and the six selected plants was different, indicating that the persistence of chlorpyrifos residues strongly depends upon leaf characteristics of the selected vegetables. PMID:24967589

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

2014-01-01

225

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

Science.gov (United States)

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

226

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

Directory of Open Access Journals (Sweden)

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

Zdravkovi? Jasmina M.

2014-01-01

227

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

Science.gov (United States)

...applicable provisions of this subpart. (1) Growing conditions . (i) The lettuce must... (ii) The lettuce must be grown in growing media that has been sterilized by steam...throughout the year in the agricultural region along Arava Highway 90 and in the...

2010-01-01

228

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

Science.gov (United States)

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

229

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

230

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

231

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

232

Indexação do Lettuce mosaic virus em sementes e plântulas de genótipos de alface / Lettuce mosaic virus indexation in seeds and seedlings of lettuce genotypes  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O Lettuce mosaic virus espécie mais importante na cultura de alface (Lactuca sativa L.) no Brasil, causando sintomas de mosaico, clareamento das nervuras, necrose, distorção foliar e redução do crescimento da planta, pode ser transmitido por sementes com uma taxa de 1% a 16%, dependendo da interação [...] dos genótipos de alface com os isolados LMV-Most ou LMV-Common. Neste trabalho, avaliou-se a detecção do LMV por PTA-ELISA, em sementes e plântulas de oito genótipos de alface: 'Vanessa Roxa', 'Baba de Verão', 'Verdinha', 'Maravilha das 4 Estações', 'Evely', 'Marcela', 687 ('Sapore' x 'Vera' ), 784 ('Sapore' x 'Vera'), utilizando anti-soro policlonal específico. O vírus não foi detectado em sementes do genótipo 'Verdinha' e, em plântulas dos genótipos 687, 'Marcela' e 'Evely', após a germinação em papel e 687, 784 e 'Marcela' com gene mo1¹, após a germinação em substrato. A avaliação individual do número de sementes infectadas foi de 100% para 'Vanessa Roxa' e 'Baba de Verão', 87,7% para 'Verdinha', 46,6% para 'Maravilha das 4 Estações' e 16,6% para 'Evely'. Nos genótipos com gene de resistência o percentual foi de 15,6%, 26,6%, 90% em 'Marcela', 687 e 784, respectivamente. A detecção do LMV por PTA-ELISA foi eficiente tanto em sementes quanto em plântulas. Abstract in english Lettuce mosaic virus is the major virus in lettuce (Lactuca sativa L.) in Brazil, causing symptoms of mosaic, vein clearing, necrosis, leaf distortion and growth reduction. The LMV is transmitted by seeds at a rate of 1% to 16%, mostly due to interaction between the isolates LMV-Most and LMV-Common [...] and the lettuce cultivar. In this study, LMV detection by PTA-ELISA in seeds and seedlings of eight lettuce genotypes, 'Vanessa Roxa', 'Baba de Verão', 'Verdinha', 'Maravilha das 4 Estações', 'Evely', 'Marcela', 687 ('Vera' X 'Sapore'), 784 ('Vera' X 'Sapore'), was evaluated, using specific polyclonal antisera. The virus was not detected in seeds of 'Verdinha' genotype and seedlings of 687, 'Marcela' and 'Evely' after germination in a paper towel or in 687, 784 and 'Marcela' with the mo1¹ resistance gene, after germination in a substrate. The individual evaluation of the number of infected seeds made by PTA-ELISA was 100% for 'Vanessa Roxa' and 'Baba de Verão', 87.7% for 'Verdinha', 46.6% for 'Maravilha das 4 Estações' and 16.6% for 'Evely'. In the genotypes with the resistance gene the percentage was 15.6%, 26.6%, 90% in 'Marcela', 687 and 784, respectively. Virus detection in seeds and seedlings by PTA-ELISA was very efficient for both seeds and seedlings.

Lillian Silveira, Pereira; Alexandre Levi Rodrigues, Chaves; Joaquim Adelino, Azevedo Filho; Addolorata, Colariccio.

233

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

Science.gov (United States)

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

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

2014-02-28

234

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

235

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

236

Irrigation with treated wastewater: effects on soil, lettuce (Lactuca sativa L.) crop and dynamics of microorganisms.  

Science.gov (United States)

The aim of this study was to evaluate the applicability of treated wastewater for horticultural crops, assess the effects of continuous use of treated water on soil and crops, and analyse the physical, chemical and biological effects of irrigation with recycled water. Two lettuce plots watered with drinking water and treated wastewater were monitored over a three year period. Nutrients, heavy metal and the dynamics of pathogen and indicator microorganism content in soil and foliar tissues were analysed. Wastewater irrigation had a high influence on soil parameters: organic matter, N, P, Ca, Al, Fe, Pb and Zn. Indicator and pathogenic microorganisms were detected in soil and plants grown in the wastewater-irrigated plot, and persisted in the soil for 27 days during the study under humid conditions. N, P, Pb and Al content were significantly higher in plant tissues of wastewater-irrigated plots than in the control after 3 years of irrigation. Harvest was significantly higher in the wastewater-irrigated plot. Wastewater can be a resource for agricultural irrigation. In any case, the possible heavy metal accumulation in soils and presence of pathogenic organisms require careful management of this alternative resource: use of a drip irrigation system, previous wastewater disinfection and a limited irrigation period are recommended. PMID:19847714

Mañas, Pilar; Castro, Elena; de Las Heras, Jorge

2009-10-01

237

Biogeography of the Pistia clade (Araceae)  

OpenAIRE

Pistia stratiotes (water lettuce) and Lemna (duckweeds) are the only free-floating aquatic Araceae. The geographic origin and phylogenetic placement of these unrelated aroids present long-standing problems because of their highly modified reproductive structures and wide geographical distributions. We sampled chloroplast (trnL-trnF and rpl20-rpsl2 spacers, trnL intron) and mitochondrial sequences (nadl b/c intron) for all genera implicated as close relatives of Pistia by morphological, restri...

Renner, Susanne S.; Zhang, Li-bing

2004-01-01

238

Effect of Different Calcium Concentration in Contaminate Soil on 90S Accumulation by the Seasonal Vegetative Growth of Lettuce  

International Nuclear Information System (INIS)

Pot experiment was conducted in greenhouse at National Center for Agriculture Research and Technology Transfer (NCARTT) farm in Baqa. To establish the effect of different calcium concentration in the contaminated soil on the 90S accumulation by the seasonal vegetative growth of lettuce. The pots were distributed in split plot in RCBD design with four replicates. The main plots of experiment were four concentration of calcium (Ca++) in the soil. The calcium soluble solution was applied and mixed with the soil. Four concentrations of calcium were 50, 100, 150 and 200 mg Ca /Kg. The sub main plots of experiment were four specific activities of Strontium-90. The contamination has been done with 90S to the surface area of the soil after one week of planting. The specific activities of 90S were: 40, 57, 73 and 89 Bq/Kg soil . The results indicate after 70 days of planting (duration of season), that the specific active of 90Sr in vegetative mass of plant (Lettuce) and in leached irrigation water at the end of season was nonsignificant increased with the increment of Ca concentration in the soil . The specific active of 90Sr reached to 1.12 Bq/Kg in plant and to 1.13 Bq/ l in irrigation water. There was strong linear correlation between specific active of 90Sr in vegetative mass of plant (Lettuce) with the increment of Ca concentration in the soil (r2= 94) , the similar results was observed for irrigthe similar results was observed for irrigation water (r2=88) . The distribution of specific active of 90Sr in the soil, plant and irrigation water was not significant effected by the increasing of specific active of 90Sr in contaminated soil and / or by increasing of Ca concentration in the soil. It was found that most of specific active of 90Sr in all treatments were remained at the end of season in the soil (96.6-97.9%). The values of Stander Transfer Factor (TFs) for 90Sr by plant or irrigation water weren't effected with increasing of specific active of 90Sr in the soil .On contrary the increasing of Ca concentration in the soil effectuate nonsignificant decreased of TFs by plant and irrigation water. The decreased in values of TFs were ranged from 0.010 to 0.018. (authors)

239

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

Science.gov (United States)

Foodborne outbreaks attributed to the contamination of fresh produce with Escherichia coli O157:H7 are a growing concern. In particular, leafy-green vegetables, including lettuce and spinach, are susceptible to contamination by irrigation water, manure, and food processing and storage practices. The survival of E. coli O157:H7 and natural microflora on Romaine lettuce stored at 4 degrees C and 15 degrees C over a 9-day period was evaluated by plate counts. A two-step reverse-transcription comparative quantitative real-time PCR assay was employed to evaluate expression of genes coding for the A subunit of Shiga-toxin 1 and 2 (stx1A and stx2A), intimin (eaeA), flagellin (fliC), sigmaS--general stress sigma factor (rpoS) and iron superoxide dismutase (sodB) in E. coli O157:H7. Results indicate that reducing the storage temperature from 15 degrees C to 4 degrees C significantly (PRomaine lettuce, however, viable populations remained after the end of both storage periods. At end of the storage period, a 0.430 and 0.180 log decrease in E. coli O157:H7 was observed at 4 degrees C and 15 degrees C, respectively. Under both storage temperatures, total aerobic plate counts increased over the duration of the experiment. An increase in E. coli O157:H7 fold expression was observed with stx2A. Although stx1A exhibited upregulation for all storage conditions, variable gene expression was observed throughout the storage period. In addition, fliC was up-regulated during storage at 15 degrees C, while transcription at 4 degrees C storage changed only slightly. Expression of eaeA was variable at 15 degrees C with a tendency towards down-regulation, however, this gene was slightly up-regulated when stored at 4 degrees C. A slight upregulation of rpoS and sodB was also observed at 4 degrees C. In conclusion, our results suggest E. coli O157:H7 may become more virulent with prolonged storage of Romaine lettuce, particularly when stored at refrigerated temperatures. PMID:19248811

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

2009-05-01

240

Attachment strength and biofilm forming ability of Bacillus cereus on green-leafy vegetables: cabbage and lettuce.  

Science.gov (United States)

The present study was designed to investigate the ability of six Bacillus cereus strains to attach and form biofilm on cabbage and lettuce surfaces. These six strains were; a reference strain DSMZ 345 and five biofilm-producing strains (aquatic strains; TUB8, TUB30, TUB31, TUB32 and TUB33) isolated from drinking-water distribution network. Hydrophobicity, biofilm formation ability, attachment strength (S(R)) of spores and vegetative cells of the six B. cereus strains were also determined. Due to their high hydrophobicity, spores of all strains had high ability to attach polystyrene and did not affect by dilution of tryptone soy broth (TSB, 1:20 v/v) in the in vitro experiment. Significant (p < 0.05) enhancement in vitro biofilm formation by vegetative cells of B. cereus was recorded in the diluted TSB. The highest biofilm formation on cabbage and lettuce surfaces was obtained by spores and vegetative cells of all tested strains on the 4(th) hour of the incubation period. These populations were significantly (p < 0.05) increased by elongating incubation time from 4 h to 24 h except DSMZ 345 and TUB8. Biofilm formation behavior obtained by B. cereus spores and vegetative cells on the polystyrene surface was different compared with that recorded on produce surface. The S(R) of both spores and vegetative cells of the studied strains to the lettuce surface was higher than that of the cabbage surface. The hydrophobicity, biofilm formation and S(R) of spores and vegetative cells of the biofilm-producing strains were higher than that of the reference strain DSMZ 345. Scanning electron microscopy (SEM) exposed random distribution of cells either on the surface or cut edge, without clear obvious affinity for the surface structures. Increasing in the presence of large clusters of cells on leaf surfaces was demonstrated after 4 and 24 h. In conclusion, use of aquatic environmental isolates is more useful for studying biofilm formation than the reference strain. Lettuce surface supported the attachment of B. cereus spores and vegetative cells compared with the cabbage surface. Further investigations are required to improve our knowledge of biofilm formation mechanisms by the human pathogenic microorganisms, especially by using the environmental and clinical isolates. To ensure safety level of green-leafy vegetables, biofilm formation after harvest should be considered as critical control point during handling of these vegetables. PMID:21839375

Elhariry, Hesham M

2011-10-01

241

Phytotoxic action of naphthoquinone juglone demonstrated on lettuce seedling roots.  

Science.gov (United States)

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

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

2014-11-01

242

EFFECTS OF TRICHODERMA HARZIANUM ON LETTUCE IN PROTECTED CULTIVATION  

OpenAIRE

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 ...

Ugur Bal; Sureyya Altintas

2008-01-01

243

Nutrient absorption and response of lettuce to phosphorus fertilization  

OpenAIRE

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

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

2012-01-01

244

Expression of 9-cis-EPOXYCAROTENOID DIOXYGENASE4 Is Essential for Thermoinhibition of Lettuce Seed Germination but Not for Seed Development or Stress Tolerance[C][W  

Science.gov (United States)

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

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

2013-01-01

245

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

246

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

247

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

Science.gov (United States)

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

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

2012-01-01

248

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

Directory of Open Access Journals (Sweden)

Full Text Available O consumo de verduras cruas desempenha importante papel na transmissão de várias doenças infecciosas pela freqüente prática de irrigação de hortas com água contaminada. O objetivo deste estudo é a avaliação das condições higiênico-sanitárias de todas as hortas produtoras de verduras de Ribeirão Preto, SP com implantação de um sistema de fiscalização. A análise laboratorial de 129 hortas revelou irregularidades em 20,1% delas, destacando-se elevada concentração de coliformes fecais em 17%, presença de Salmonella em 3,1% e de vários enteroparasitas (Ascaris sp, Ancylostomidae, Strongyloides sp, Hymenolepis nana e Giardia sp em 13,1%. A repetição da análise das hortas irregulares determinou a interdição definitiva de uma delas; todas as demais foram aprovadas, comprovando a eficácia do sistema de fiscalização, particularmente com a implantação, inédita no país, do certificado de vistoria sanitária.The ingesting of raw vegetables plays an important role in the transmission of several infectious diseases due to the high frequency of irrigation with wastewater. The objective of this study was to evaluate the sanitary conditions of all lettuce producing crops in Ribeirão Preto through microbiological and parasitological analysis of both irrigation water and lettuce together with the implantation of an effective crop monitoring. Laboratory analysis of 129 crops showed irregularities in 26 (20.1% of these: high concentration of fecal coliforms in 17% of the lettuce, presence of Salmonella in 3.1% and several enteroparasites (Ascaris sp, Ancylostomidae, Strongyloides sp, Hymenolepis nana, and Giardia sp in 13.1%. Persistent irregularities determined the definitive closing down of one producer; all of the remaining 128 crops were eventually approved, thus demonstrating the efficacy of lettuce crop monitoring. Crops approved in the laboratory analysis were awarded a Sanitary Inspection Certificate - an unprecedented procedure in our Country - that resulted in a better acceptance of the monitoring.

Osvaldo M. Takayanagui

2000-04-01

249

DEMONSTRATION OF IRRIGATION RETURN FLOW WATER QUALITY CONTROL IN THE MESILLA VALLEY, NEW MEXICO  

Science.gov (United States)

A 182-ha operating farm was used to demonstrate the water pollution control benefits of implementing improved irrigation management techniques and structures. The commodity crops produced on the farm included wheat, tomatoes, cotton, lettuce, peppers, chiles, grain sorghum, and a...

250

Manure- and biosolids-resident murine norovirus 1 attachment to and internalization by Romaine lettuce.  

Science.gov (United States)

The attachment of murine norovirus 1 (MNV) in biosolids, swine manure, and dairy manure to Romaine lettuce and internalization of this virus were evaluated. The MNV in animal manures had behavior similar to that of pure MNV; however, MNV in biosolids had significantly higher levels of attachment and internalization than pure MNV or MNV in manures. The incubation time did not affect the attachment of MNV in biosolids or manure. Confocal microscopy was used to observe MNV on lettuce after SYBR gold-labeled MNV was added directly to lettuce or after lettuce was submersed in labeled virus. MNV was observed on the lettuce surface, inside open cuts, and occasionally within stomata. In general, lettuce pieces with a long cut on the edge and short cuts on the stem was more likely to contain internalized MNV than intact lettuce pieces, as observed by confocal microscopy; however, while the difference was visible, it was not statistically significant. This study showed that the presence of MNV in biosolids may increase the risk of fresh produce contamination and that the MNV in open cuts and stomata is likely to be protected from sanitization. PMID:19933344

Wei, Jie; Jin, Yan; Sims, Tom; Kniel, Kalmia E

2010-01-01

251

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

International Nuclear Information System (INIS)

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

252

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

253

Effect of CO_2 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 CO_2 enrichment effects on the chemical composition of lettuce and radish. These crops are useful model systems for a Controlled Ecological Life-Support System (CELSS), largely because of their relatively short production cycles. Lettuce (Lactuca sativa L.) cultivar `Waldmann's Green' and radish (Raphanus sativus L.) cultivar `Giant White Globe' were grown both in the field and in controlled environments, where hydroponic nutrient solution, light, and temperature were regulated, and where CO_2 levels were controlled at 400, 1000, 5000, or 10,000 ppm. Plants were harvested at maturity, dried, and analyzed for proximate composition (protein, fat, ash, and carbohydrate), total nitrogen (N), nitrate N, free sugars, starch, total dietary fiber, and minerals. Total N, protein N, nonprotein N (NPN), and nitrate N generally increased for radish roots and lettuce leaves when grown under growth chamber conditions compared to field conditions. The nitrate-N level of lettuce leaves, as a percentage of total NPN, decreased with increasing levels of CO_2 enrichment. The ash content of radish roots and of radish and lettuce leaves decreased with increasing levels of CO_2 enrichment. The levels of certain minerals differed between field- and chamber-grown materials, including changes in the calcium (Ca) and phosphorus (P) contents of radish roots and lettuce leaves, resulting in reduced Ca/P ratio for chamber-grown materials. The free-sugar contents were similar between the field and chamber-grown lettuce leaves, but total dietary fiber content was much higher in the field-grown plant material. The starch content of growth-chamber lettuce increased with CO_2 level.

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

254

Detection of viable Salmonella in lettuce by propidium monoazide real-time PCR.  

Science.gov (United States)

Contamination of lettuce by Salmonella has caused serious public health problems. Polymerase chain reaction (PCR) allows rapid detection of pathogenic bacteria in food, but it is inaccurate as it might amplify DNA from dead target cells as well. This study aimed to investigate the stability of DNA of dead Salmonella cells in lettuce and to develop an approach to detecting viable Salmonella in lettuce. Salmonella-free lettuce was inoculated with heat-killed Salmonella Typhimurium cells and stored at 4 °C. Bacterial DNA extracted from the sample was amplified by real-time PCR targeting the invA gene. Our results indicate that DNA from the dead cells remained stable in lettuce for at least 8 d. To overcome this limitation, propidium monoazide (PMA), a dye that can selectively penetrate dead bacterial cells and cross-link their DNA upon light exposure, was combined with real-time PCR. Lettuce samples inoculated with different levels of dead or viable S. Typhimurium cells were treated or untreated with PMA before DNA extraction. Real-time PCR suggests that PMA treatment effectively prevented PCR amplification from as high as 10(8) CFU/g dead S. Typhimurium cells in lettuce. The PMA real-time PCR assay could detect viable Salmonella at as low as 10(2) CFU/mL in pure culture and 10(3) CFU/g in lettuce. With 12-h enrichment, S. Typhimurium of 10(1) CFU/g in lettuce was detectable. In conclusion, the PMA real-time PCR assay provides an alternative to real-time PCR assay for accurate detection of Salmonella in food. PMID:22417362

Liang, Ningjian; Dong, Jin; Luo, Laixin; Li, Yong

2011-05-01

255

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

256

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

Directory of Open Access Journals (Sweden)

Full Text Available An efficient method for constructing transgenic lettuce cultivars by Agrobacterium tumefaciens was described by Torres et al., 1993. In the present work, an improvement of the above procedure is described and applied to transform the cultivar Grand Rapids with a mutated P5CS gene. The major modifications were concerned with turning more practical the transformation and regeneration protocols. Also we tried to improve transformation steps by increasing injured area in explants and prolonging co-cultivation with Agrobacteria (in larger concentration. A more significant selective pressure was used against non-transformed plants and bacteria. In these work we were concerned to obtain T1 and T2 seeds. The P5CS gene codes for a delta¹-pyrroline-5-carboxylate synthetase, a bifunctional enzyme that catalyzes two steps of proline biosynthesis in plants (Zhang et al., 1995; Peng et al., 1996, while the mutated gene is insensitive to feedback inhibition by proline. The potential benefit of this gene is to confer water stress resistance (drought, salt, cold due to increased intracellular levels of proline that works like an osmoprotectant. In this work could obtain and characterize transgenic lettuce lineages which are resistant to freezing temperature.

Pileggi Marcos

2001-01-01

257

Cinnamaldehyde inhibits phenylalanine ammonia-lyase and enzymatic browning of cut lettuce.  

Science.gov (United States)

Stored cut lettuce gradually turns brown on the cut section after several days of storage, because cutting induces phenylalanine ammonia-lyase (PAL) activity, the biosynthesis of polyphenol is promoted, and the polyphenols are oxidized by polyphenol oxidase. In this study, we screened for inhibitors of PAL derived from fermented broths of microbes and from foods and found that a cinnamon extract definitely inhibited PLA of cut lettuce. An active component was isolated by chromatographic procedures and was identified as trans-cinnamaldehyde. Browning of cut lettuce immersed in a solution containing trans-cinnamaldehyde was definitely repressed. PMID:16556984

Fujita, Narumi; Tanaka, Eriko; Murata, Masatsune

2006-03-01

258

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

259

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

260

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

261

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  

Directory of Open Access Journals (Sweden)

Full Text Available Este trabalho teve o objetivo de avaliar o desenvolvimento, a produção e a qualidade sanitária da cultura da alface irrigada com águas residuárias originadas da suinocultura e da piscicultura. Os tratamentos avaliados foram: T1 - alface irrigada com água de origem subterrânea e adubação suplementar; T2 - alface irrigada com água residuária de viveiro de peixes alimentados com ração; T3 - alface irrigada com água residuária originária de lagoa de estabilização de dejetos de suínos, e T4 - água de lagoa de cultivo de algas, alimentada com resíduo de biodigestor de dejeto de suíno. Os tratamentos não apresentaram diferenças significativas para altura da alface, diâmetro da cabeça, comprimento da raiz, massa da raiz, massa total da planta, massa fresca e massa seca; os tratamentos T4 e T2 apresentaram os maiores valores para comprimento da maior folha e número de folhas, respectivamente; em geral, as análises foliares e a extração de macro e micronutrientes pela cultura não apresentaram diferenças significativas; ocorreu contaminação de coliformes fecais e totais em todos os tratamentos; não ocorreu contaminação de Escherichia coli em todos os tratamentos; todos os Coeficientes de Uniformidade de Christiansen (CUC encontrados foram acima de 85%, exceto para o tratamento T3 que foi de 74,05%; ocorreram alterações químicas no solo proporcionais às características das águas utilizadas nos respectivos tratamentos.The objective of this work was to evaluate development, production and sanitary quality of the irrigated lettuce with wastewater from fish and swine activities. The evaluated treatments was: T1 - lettuce irrigated with water from underground origin and supplemental fertilization; T2 - lettuce irrigated with wastewater from fish activities and fish fed with ration; T3 - lettuce irrigated with wastewater from swine treated in stabilization lagoon; and T4 - lettuce irrigated with effluent from seaweed 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

2007-04-01

262

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

Directory of Open Access Journals (Sweden)

Full Text Available A determinação do consumo de água de irrigação é fundamental para o manejo correto dos cultivos irrigados. Este trabalho teve o objetivo de estudar o desenvolvimento de duas cultivares da alface (AF 1743 e OGR 326, em ambiente protegido, no município de Juazeiro-BA, sob dois métodos de manejos de irrigação: reposição de água de irrigação determinada por tensiometria (M1 e reposição de água determinada na evaporação de água de tanque reduzido (M2, instalados em ambiente protegido. Observou-se efeito de interação entre os tratamentos impostos e as cultivares de alface estudadas, para a massa fresca das raízes das plantas. O uso da tensiometria promoveu desempenho superior para as variáveis de produção analisadas, como observado na massa fresca da parte aérea, apresentando média geral de 145,0 g, enquanto no manejo M2 tal valor foi de 59,4 g. Dentre as cultivares analisadas para referida variável, observou-se um resultado superior para a cultivar OGR 326 quando comparada à AF 1743.The determination of the water consumption is fundamental for the correct management of irrigated crops. The development of two lettuce cultivars (AF 1743 and OGR 326 was determined, when cultivated in a protected environment under two irrigation management methods: water consumption determined by the tensiometry (M1 and water consumption determined by evaporation of water in the reduced pan (M2, which were installed inside the protected environment. There was significant interaction among the imposed treatment and the cultivars of lettuce studied, for the fresh weight of the roots of the plants. The use of tensiometry promoted superior performance for the analyzed production variables as observed in the fresh weight of the aboveground part, with an overall average of 145.0 g, whereas for the management M2 the overall average was 59.4 g. For this variable, among the cultivars a superior result was obtained for the cultivar OGR 326 in comparison to AF1743.

George RL Bandeira

2011-06-01

263

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

264

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.

265

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

266

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

267

EVALUATION OF FUNGICIDES FOR CONTROLLING BOTTOM ROT OF ICEBERG LETTUCE, 2001 AND 2002  

Science.gov (United States)

Application of fungicides such as Quadris, Pristin, Flint Rovral and Switch to the base of young lettuce plants after thinning and one week later reduced the incidence of disease caused by Rhizoctonia solani....

268

Changes in the Content of Free and Conjugated Polyamines during Lettuce (Lactuca sativa) Growth.  

Science.gov (United States)

Polyamines (PAs) in plant foods are relevant due to the association of these bioactive nutrients with health and disease. The scope of the present study was to monitor the content of free, conjugated, and total (free + conjugated) putrescine (Put), spermidine (Spd), and spermine (Spm) at five stages of lettuce growth in three different greenhouses. The daily intake of PAs from lettuce consumption was estimated since its consumption represents about 7.2% of vegetables intake. Results showed that the content of free Put, Spd, and Spm decreased during plant growth, while the content of conjugated Put, Spd, and Spm increased. Nevertheless, the total PA content remained fairly constant. Significant differences were observed in the PAs content in lettuces grown in different greenhouses. The conjugated fraction of PAs in mature lettuces has an important contribution to the total PAs and will certainly influence the bioavailability and/or bioactivity of dietary polyamines. PMID:25539287

Pinto, Edgar; Ferreira, Isabel M P L V O

2015-01-21

269

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

Science.gov (United States)

Low temperature regular phosphine fumigations under the normal oxygen level and oxygenated phosphine fumigations under superatmospheric oxygen levels were compared for efficacy against the aphid, Nasonovia ribisnigri (Mosley), and effects on postharvest quality of romaine and head lettuce. Low temperature regular phosphine fumigation was effective against the aphid. However, a 3 d treatment with high phosphine concentrations of > or = 2,000 ppm was needed for complete control of the aphid. Oxygen greatly increased phosphine toxicity and significantly reduced both treatment time and phosphine concentration for control of N. ribisnigri. At 1,000 ppm phosphine, 72 h regular fumigations at 6 degrees C did not achieve 100% mortality of the aphid. The 1,000 ppm phosphine fumigation under 60% O2 killed all aphids in 30 h. Both a 72 h regular fumigation with 2,200 ppm phosphine and a 48 h oxygenated fumigation with 1,000 ppm phosphine under 60% O2 were tested on romaine and head lettuce at 3 degrees C. Both treatments achieved complete control of N. ribisnigri. However, the 72 h regular fumigation resulted in significantly higher percentages of lettuce with injuries and significantly lower lettuce internal quality scores than the 48 h oxygenated phosphine fumigation. Although the oxygenated phosphine fumigation also caused injuries to some treated lettuce, lettuce quality remained very good and the treatment is not expected to have a significant impact on marketability of the lettuce. This study demonstrated that oxygenated phosphine fumigation was more effective and less phytotoxic for controlling N. ribisnigri on harvested lettuce than regular phosphine fumigation and is promising for practical use. PMID:22812116

Liu, Yong-Biao

2012-06-01

270

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

OpenAIRE

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

Legarrea, S.; Di?az, B. M.; Plaza, M.; Barrios, L.; Morales, Ignacio; Vin?uela Sandoval, Elisa; Fereres Castiel, Alberto

2012-01-01

271

Determination of anthraquinone in technical material, formulations, and lettuce by high performance liquid chromatography.  

Science.gov (United States)

Foraging on lettuce seeds and seedlings by horned larks (Eremophila alpestris) causes millions of dollars in losses to the California lettuce crop annually. Anthraquinone (AQ; 9,10-anthracenedione) has been shown to deter pest birds from consuming the seeds and seedlings of several plant species and was evaluated as a repellent to horned larks when applied to lettuce seedlings. A set of analytical methods using simple liquid extraction followed by high-performance liquid chromatography analysis were developed for the quantitation of AQ as technical material, as an active ingredient in a commercial formulation, and as a residue in lettuce plants. The methods were easy, reliable, and repeatable. AQ recoveries from control formulation fortified to concentrations of either 24 or 600 mg g(-)(1) were 99 (+/-1.2%) and 98% (+/-1.2%), respectively, with a control formulation method limit of detection (MLOD) of 0.50 mg g(-)(1). Control lettuce tissues from three growth stages were AQ-fortified to concentrations of 0.50 and 500 microg g(-)(1). The resulting AQ recoveries for the two fortification levels were 99 (+/-8.5) and 89% (+/-1.5%) for 11 day old seedlings, 95 (+/-2.6%) and 86% (2.1%) for 16 day old plants, and 92 (+/-1.4%) and 93% (+/-1.1%) for adult head lettuce cover leaves, respectively. The MLODs for the same three lettuce tissues were 0.055, 0.058, and 0.077 microg g(-)(1), respectively. These methods were used to quantify AQ residues from field-grown, treated lettuce and associated fortified quality control samples. PMID:12059136

Mauldin, Richard E; Primus, Thomas M; Volz, Stephanie A; Kimball, Bruce A; Johnston, John J; Cummings, John L; York, Darryl L

2002-06-19

272

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

OpenAIRE

Lettuce image segmentation which based on computer image processing is the premise of non-destructive testing of lettuce quality. The traditional 2-D maximum entropy algorithm has some faults, such as low accuracy of segmentation, slow speed, and poor anti-noise ability. As a result, it leads to the problems of poor image segmentation and low efficiency. An improved 2-D maximum entropy algorithm is presented in this paper. It redistricts segmented regions and furtherly classifies the segmente...

Xiaodong Zhang; Hongyan Gao; Xiaohong Wu; Yan Wang; Jun Sun

2012-01-01

273

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

OpenAIRE

This study was conducted to evaluate the resistance of 212 accessions of lettuce germplasm to gray mold disease caused by Botrytis cinerea. The lettuce germplasm were composed of five species: Lactuca sativa (193 accessions), L. sativa var. longifolia (2 accessions), L. sativa var. crispa (2 accessions), L. saligna (2 accessions), and L. serriola (1 accession); majority of these originated from Korea, Netherlands, USA, Russia, and Bulgaria. After 35 days of spray inoculation with conidial sus...

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

2014-01-01

274

Evaluation of three fungicides for control of soilborne diseases of lettuce seedlings  

OpenAIRE

Lettuce (Lactuca sativa L.) seedlings diseases caused by soilborne pathogens are characterised by root rot, stem rot and damping-off of the seedlings that can occur at any time during growth. Fusarium solani, Pythium ultimum and Rhizoctonia solani are known to be the important destructive pathogens of lettuce, causing severe yield losses in South Africa. The aim of this research was to evaluate the effects of three selected fungicides to control these pathogen...

Kalonji Kabengele Muzela, J. B.

2008-01-01

275

Manure- and Biosolids-Resident Murine Norovirus 1 Attachment to and Internalization by Romaine Lettuce?  

OpenAIRE

The attachment of murine norovirus 1 (MNV) in biosolids, swine manure, and dairy manure to Romaine lettuce and internalization of this virus were evaluated. The MNV in animal manures had behavior similar to that of pure MNV; however, MNV in biosolids had significantly higher levels of attachment and internalization than pure MNV or MNV in manures. The incubation time did not affect the attachment of MNV in biosolids or manure. Confocal microscopy was used to observe MNV on lettuce after SYBR ...

Wei, Jie; Jin, Yan; Sims, Tom; Kniel, Kalmia E.

2009-01-01

276

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

OpenAIRE

The aerial surfaces of plants, or phyllosphere, are microbial habitats important to plant and human health. In order to accurately investigate microbial interactions in the phyllosphere under laboratory conditions, the composition of the phyllosphere microbiota should be representative of the diversity of microorganisms residing on plants in nature. We found that Romaine lettuce grown in the laboratory contained 10- to 100-fold lower numbers of bacteria than age-matched, field-grown lettuce. ...

Williams, Thomas R.; Marco, Maria L.

2014-01-01

277

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

OpenAIRE

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) ...

Iuliana Cretescu; Caprita Rodica; Velicevici Giancarla; Camen Dorin; Sirbu Corina; Buzamat Genoveva; Ropciuc Sorina

2014-01-01

278

Sensory quality attributes of lettuce obtained using different harvesting performance systems  

OpenAIRE

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...

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

2013-01-01

279

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

OpenAIRE

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

Roosta, H. R.

2010-01-01

280

Estimation of vector propensity for Lettuce mosaic virus based on viral detection in single aphids  

OpenAIRE

Lettuce mosaic virus (LMV) is transmitted by aphids nonpersistently causing severe disease outbreaks in commercial lettuce crops. New strategies to control plant viruses have arisen based on molecular techniques, which analyze plantvirus- vector interactions. In this work, two PCR-based methods with a previous immunocapture phase, have been developed to detect LMV in single aphids. Detection rates using a RT-nested-PCR method in single aphids and transmission efficiency of Myzus p...

Moreno, Ara?nzazu; Bertolini, E.; Olmos, A.; Cambra, Mariano; Fereres, Alberto

2007-01-01

281

Nitrate content in dandelion (Taraxacum officinale) and lettuce (Lactuca sativa) from organic and conventional origin: intake assessment.  

Science.gov (United States)

To estimate the actual intake of nitrate by consumption of different lettuce varieties, 52 samples of lettuce of different origins and dandelion from 15 different areas of northeast Slovenia were analysed. For determination of actual nitrate content, a continuous flow method was used. The lowest nitrate content was detected in dandelion, with a mean value of 195?mg?kg(-1) (ranging 47-487?mg?kg(-1)). Nitrate content in lettuce of different origins ranged 85-3237?mg?kg(-1), with a mean value of 1196?mg?kg(-1). The mean nitrate content in organically cultivated lettuce was 890?mg?kg(-1), which was considerably lower than the nitrate level in conventionally cultivated lettuce (1298?mg?kg(-1)). Consumption of 100?g of dandelion would result in a maximal nitrate intake corresponding to 22% of the acceptable daily intake (ADI), with values up to seven times higher for lettuce. PMID:24779737

Gorenjak, Alenka Hmelak; Koležnik, Urška Rizman; Cenci?, Avrelija

2012-01-01

282

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

283

Effect of methyl jasmonate on phenolic compounds and carotenoids of romaine lettuce (Lactuca sativa L.).  

Science.gov (United States)

The effect of exogenous methyl jasmonate (MeJA) on antioxidative compounds of romaine lettuce ( Lactuca sativa L.) was investigated. Lettuces were treated with various MeJA solutions (0, 0.05, 0.1, 0.25, and 0.5 mM) before harvest. Total phenolic compounds content and antioxidant capacity of romaine lettuce significantly increased after MeJA treatments (0.1, 0.25, and 0.5 mM). The total content of phenolic compounds of the romaine lettuce treated with 0.5 mM MeJA (31.6 microg of gallic acid equivalents/mg of dry weight) was 35% higher than that of the control. The increase in phenolic compound content was attributed to a caffeic acid derivative and an unknown phenolic compound, which also contributed to increased antioxidant capacity. The induction of phenylalanine ammonia-lyase (PAL) activity by the MeJA treatment indicated that phenolic compounds were altered due to the activation of the phenylpropandoid pathway. Total content of carotenoids, including lutein and beta-carotene, of the MeJA-treated lettuce did not change after 8 days of treatment, whereas the content of the control without MeJA decreased after 8 days. This research indicated that preharvest application of MeJA could increase the nutritional value of romaine lettuce under determined conditions discussed in this work. PMID:17990849

Kim, Hyun-Jin; Fonseca, Jorge M; Choi, Ju-Hee; Kubota, Chieri

2007-12-12

284

The effect of growth regulators on the healthiness, growth and sprouting of inflorescence shoot of lettuce  

Directory of Open Access Journals (Sweden)

Full Text Available Investigations were carried out under greenhouse conditions on lettuce cv. Ilanka. Seeds were sown in January 1982 and 1984. Lettuce was cultivated to middle of June up to full flowering time. It was found that the preparation fenoprop (2,4,5-trichlorofenoxypropionic acid as a dimethylamine salt in concentrations of 10, 20 and 50 mg·dm-3 significantly decreased latex tipburn symptoms. Fenoprop increased the healthiness of the plants because treated plants were also less attacked by grey mould Botritis sp. Fenoprop also inhibited head formation in lettuce, but the weight of these plants was never smaller than control ones. Sometimes the weight of plants treated with fenoprop was significantly higher than of the control plants. Lettuce plants without heads had bolted earlier. Only the concentration of 100 mg·dm-3 of fenoprop retarded plant growth. The effect of K-NAA (potassium salt of ?-naphthaleneacetic acid on lettuce was weaker than the effect of fenoprop. After K-NAA treatment at a concentration of 25 mg·dm-3, lettuce plants formed normal heads but latex tipburn symptoms were retarded.

Jan Borkowski

1988-12-01

285

Phenolic contents of lettuce, strawberry, raspberry, and blueberry crops cultivated under plastic films varying in ultraviolet transparency  

OpenAIRE

The levels of health-related phytochemicals were determined in lettuce leaf and in strawberry, raspberry and blueberry fruits grown in near-commercial conditions under plastic films of three different UV transparencies. In the red lettuce Lollo Rosso, total phenolics, anthocyanin, luteolin and quercetin levels were all raised by changing from a UV blocking film to a film of low UV transparency, and to a film of high UV transparency. The related green lettuce, Lollo Biondo, cultivated under t...

Ordidge, Matthew; Garci?a-maci?as, P.; Battey, Nicholas Hugh; Gordon, Michael Harry; Hadley, Paul; John, Philip; Lovegrove, Julie Anne; Vysini, E.; Wagstaffe, Alexandra

2010-01-01

286

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

287

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

288

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

289

Radiotracer studies of maneb residues in lettuce plants  

International Nuclear Information System (INIS)

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

290

Quorum Sensing Activity of Enterobacter asburiae Isolated from Lettuce Leaves  

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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

291

Changes during imbition of irradiated dry seeds of lettuce  

International Nuclear Information System (INIS)

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

292

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

Science.gov (United States)

In recent decades, romaine lettuce has been one of the fastest growing vegetables with respect to its consumption and production. An understanding is needed of the effect of major phenolic phytochemicals from romaine lettuce on biological protection for neuron-like PC-12 cells. Phenolics in fresh romaine lettuce were extracted, and then its total phenolics and total antioxidant capacity were measured spectrophotometrically. Neuroprotective effects of phenolic extract of romaine lettuce and its pure caffeic acid derivatives (caffeic, chicoric, chlorogenic, and isochlorogenic acids) in PC-12 cells were evaluated using two different in vitro methods: lactate dehydrogenase release and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assays. Total phenolics and total antioxidant capacity of 100 g of fresh romaine lettuce averaged 22.7 mg of gallic acid equivalents and 31.0 mg of vitamin C equivalents, respectively. The phenolic extract of romaine lettuce protected PC-12 cells against oxidative stress caused by H(2)O(2) in a dose-dependent manner. Isochlorogenic acid, one of the phenolics in romaine lettuce, showed stronger neuroprotection than the other three caffeic acid derivatives also found in the lettuce. Although romaine lettuce had lower levels of phenolics and antioxidant capacity compared to other common vegetables, its contribution to total antioxidant capacity and antineurodegenerative effect in human diets would be higher because of higher amounts of its daily per capita consumption compared to other common vegetables. PMID:20553182

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

2010-08-01

293

Cadmium deposition and hepatic microsomal induction in mice fed lettuce grown on municipal sludge-amended soil  

Energy Technology Data Exchange (ETDEWEB)

Romaine lettuce, cultured on soil amended with municipal sludges, was fed as 45% of their diet to mice. The concentrations of Cd and Zn in the lettuce correlated closely with the element levels in the respective sludges on which they were grown. When compared to control mice, Cd showed significantly (p < 0.05) higher concentrations in the kidneys of mice fed Baltimore, Milwaukee, and a Washington, D.C. sludge-grown lettuce. The hepatic microsomal enzyme, p-nitroanisole O-demethylase was significantly (p < 0.05) higher than controls in the mice fed the lettuce grown on Milwaukee sludge.

Chaney, R.L. (Dept. of Agriculture, Beltsville, MD); Stoewsand, G.S.; Bache, C.A.; Lisk, D.J.

1978-01-01

294

Envelhecimento acelerado em sementes de alface Accelerated aging in lettuce seeds  

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Full Text Available Objetivou-se adequar a metodologia do teste de envelhecimento acelerado para avaliação do potencial fisiológico de sementes de quatro lotes dos genótipos de alface 'Babá de verão', 'Tainá' e 'Vera', aplicando-se o método tradicional e com o uso de solução saturada de NaCl. Para tal, as sementes foram submetidas à determinação do teor de água, testes de germinação e vigor (primeira contagem, condutividade elétrica, emergência em bandeja, índice de velocidade de emergência incluindo o teste de envelhecimento acelerado, conduzido nos períodos de 24, 48, e 72 horas, a 41°C com e sem solução saturada de NaCl. O experimento foi conduzido em delineamento inteiramente casualizado com quatro repetições. Os procedimentos tradicional e com o uso da solução saturada de NaCl por 72 horas foram sensíveis em estratificar os lotes em níveis de vigor, além de estarem de acordo com os demais testes utilizados. Portanto, o envelhecimento acelerado de sementes de alface deve ser feito utilizando o período de 72 horas, podendo ser realizado tanto pelo método tradicional quanto pelo método da solução saturada de NaCl.The objective was to adapt the methodology of the accelerated aging test to evaluate the physiological potential of seeds of four lots of lettuce genotypes 'Babá de verão', 'Tainá' and 'Vera' applying the traditional method and using a saturated NaCl solution. So, the seeds were subjected to determination of water content, seed germination and vigor (first count, electrical conductivity, speed emergency index, emergency tray including the accelerated aging test conducted in periods of 24, 48, 72 hours at 41°C with and without saturated solution of NaCl. The experiment was conducted in a randomized design with four replications. The accelerated aging traditional and saturated solution of NaCl by 72h was more sensitive to stratify the lots in vigor levels. Therefore, accelerated aging of seeds of lettuce should be made using the period of 72h and can be accomplished either by the traditional method and by the saturated NaCl solution method.

Rafael Marani Barbosa

2011-11-01

295

Envelhecimento acelerado em sementes de alface / Accelerated aging in lettuce seeds  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese Objetivou-se adequar a metodologia do teste de envelhecimento acelerado para avaliação do potencial fisiológico de sementes de quatro lotes dos genótipos de alface 'Babá de verão', 'Tainá' e 'Vera', aplicando-se o método tradicional e com o uso de solução saturada de NaCl. Para tal, as sementes fora [...] m submetidas à determinação do teor de água, testes de germinação e vigor (primeira contagem, condutividade elétrica, emergência em bandeja, índice de velocidade de emergência) incluindo o teste de envelhecimento acelerado, conduzido nos períodos de 24, 48, e 72 horas, a 41°C com e sem solução saturada de NaCl. O experimento foi conduzido em delineamento inteiramente casualizado com quatro repetições. Os procedimentos tradicional e com o uso da solução saturada de NaCl por 72 horas foram sensíveis em estratificar os lotes em níveis de vigor, além de estarem de acordo com os demais testes utilizados. Portanto, o envelhecimento acelerado de sementes de alface deve ser feito utilizando o período de 72 horas, podendo ser realizado tanto pelo método tradicional quanto pelo método da solução saturada de NaCl. Abstract in english The objective was to adapt the methodology of the accelerated aging test to evaluate the physiological potential of seeds of four lots of lettuce genotypes 'Babá de verão', 'Tainá' and 'Vera' applying the traditional method and using a saturated NaCl solution. So, the seeds were subjected to determi [...] nation of water content, seed germination and vigor (first count, electrical conductivity, speed emergency index, emergency tray) including the accelerated aging test conducted in periods of 24, 48, 72 hours at 41°C with and without saturated solution of NaCl. The experiment was conducted in a randomized design with four replications. The accelerated aging traditional and saturated solution of NaCl by 72h was more sensitive to stratify the lots in vigor levels. Therefore, accelerated aging of seeds of lettuce should be made using the period of 72h and can be accomplished either by the traditional method and by the saturated NaCl solution method.

Rafael Marani, Barbosa; Denis Santiago da, Costa; Marco Eustáquio de, Sá.

1899-19-01

296

Plant growth, metabolism and adaptation in relation to stress conditions. XXI. Reversal of harmful NaCl-effects in lettuce plants by foliar application with urea  

OpenAIRE

In relation to water control levels, administration of NaCl at low (3 dSm-1), medium (5 dSm-1) or high (7 dSm-1) concentration, in the growth medium of the lettuce plants, induced significant decreases in growth components as well as in the metabolites and enzymes determined, at vegetative and adult growth stages. On the other hand, significant increases in all growth and photosynthetic components determined, as well as in carbohydrate contents and in the activities of the antioxidant enz...

Mahmoud Elbaz Younis; Mohammed Naguib Hasaneen; Adel Rezk Ahmed; Dalia Mohammed El-Bialy

2008-01-01

297

Whole-head washing, prior to cutting, provides sanitization advantages for fresh-cut Iceberg lettuce (Latuca sativa L.).  

Science.gov (United States)

The efficacy of two leafy produce wash methods, the traditional cutting-before-washing process and a new washing-before-cutting method, on reduction of Escherichia coli O157:H7 inoculated on Iceberg lettuce was compared. The washing tests were conducted in a pilot-scale washer using combinations of water, chlorine, peroxyacetic acid, and ultrasound. The washing-before-cutting process recorded an E. coli O157:H7 count reduction 0.79-0.80 log?? CFU/g higher than that achieved with the cutting-before-washing process in treatments involving only a sanitizer. When ultrasound was applied to the washing-before-cutting process, a further improvement of 0.37-0.68 log?? CFU/g in microbial count reduction was obtained, reaching total reductions of 2.43 and 2.24 log?? CFU/g for chlorine and peroxyacetic acid washes, respectively. PMID:24704862

Palma-Salgado, Sindy; Pearlstein, Arne J; Luo, Yaguang; Park, Hee Kyung; Feng, Hao

2014-06-01

298

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

299

Response of uptake and translocation of phenanthrene to nitrogen form in lettuce and wheat seedlings.  

Science.gov (United States)

Polycyclic aromatic hydrocarbons (PAHs) are widespread chemicals that are potentially carcinogenic and toxic to human due to dietary intake of food crops contaminated by PAHs. To date, the mechanisms underlying root uptake and acropetal translocation of PAHs in crops are poorly understood. Here we describe uptake and translocation of phenanthrene (a model PAH) in relation to nitrogen form and concentration in wheat and lettuce seedlings. At concentrations of 0-15 mM, phenanthrene uptake by roots is enhanced with an increase in ammonium and inhibited with an increment of nitrate. Phenanthrene concentration in shoots is much lower than in roots, suggesting that the direction of phenanthrene transport is acropetal. Ammonium reduces both phenanthrene accumulation and bioconcentration factor in shoots, as well as translocation factor, but nitrate elevates them. Phenanthrene uptake increases nutrient solution pH in the treatments with either nitrate or ammonium. Thus, it is concluded that the root uptake and acropetal translocation of phenanthrene in crops are associated with nitrogen form. Our results provide both a novel insight into the mechanism on PAH transport in higher plants and a promising agronomic strategy to minimize PAH contamination in crops or to improve phytoremediation of PAH-contaminated soils or water via nitrogen management. PMID:25408074

Zhan, Xinhua; Yuan, Jiahan; Yue, Le; Xu, Guohua; Hu, Bing; Xu, Renkou

2014-11-20

300

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

Directory of Open Access Journals (Sweden)

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

Márcio Martinello Sanches

2007-12-01

301

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

302

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

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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

303

Ultralow oxygen treatment for postharvest control of western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae), on iceberg lettuce. I. Temperature, time & oxygen level on insect mortality & lettuce quality  

Science.gov (United States)

Ultralow oxygen (ULO) treatments with different oxygen levels, treatment times, and temperatures were studied to determine responses of western flower thrips and effects on postharvest quality of iceberg lettuce. Over 99.6% mortality rates of thrips were achieved in three ULO treatments of 2, 3, and...

304

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.

1141-11-01

305

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

Directory of Open Access Journals (Sweden)

Full Text Available Dois experimentos foram conduzidos, por dois anos consecutivos, em Seropédica, RJ, com o objetivo de avaliar o desempenho agronômico dos consórcios das cultivares de alface 'Regina 71' (lisa e 'Verônica' (crespa com cenoura 'Brasília' e rabanete 'Híbrido nº 19', sob manejo orgânico, assim como determinar as quantidades de macronutrientes exportadas. O delineamento experimental usado foi o de blocos ao acaso, com quatro repetições. No primeiro experimento, os tratamentos consistiram de alface crespa em consórcio com cenoura, alface crespa em consórcio com rabanete e os cultivos solteiros. No segundo experimento, usou-se alface lisa em lugar da crespa. Nos consórcios entre cenoura e alface crespa ou lisa, foram observados índices de uso eficiente da terra, superiores a 1,60. Nos consórcios de rabanete com alface, crespa ou lisa, esses índices foram de 1,54 e 1,27, respectivamente. As quantidades de nutrientes extraídas do sistema pelos produtos colhidos foram inferiores aos aportes efetuados, evidenciando a viabilidade de qualquer dos consórcios avaliados.Two experiments were carried out, in two consecutive years, at Seropédica, RJ, Brazil, aiming to evaluate the agronomic performance of intercropping of lettuce cvs. Regina 71 (smooth leaf and Verônica (crisp leaf with carrot (cv. Brasília and radish (cv. Hybrid number 19, under organic management. The amount of nutrients exported from the system by harvesting was also evaluated. The experimental design used was of completely randomized blocks, with four replications. In the first experiment, treatments consisted of lettuce with crisp leaves intercropped with carrot, lettuce with crisp leaves intercropped with radish and sole crops. In the second experiment, lettuce with smooth leaves was used instead of lettuce with crisp leaves. Intercropping of carrot and lettuce, with crisp or smooth leaf, presented land equivalent ratios higher than 1.60. Intercropping of radish and 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

2006-07-01

306

Antimicrobial activity of Cinnamaldehyde and Sporan against Escherichia coli O157:H7 and Salmonella on lettuce  

Science.gov (United States)

Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce wash; the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Lettuce were cut into pieces (...

307

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

Science.gov (United States)

Foodborne outbreaks associated with the consumption of fresh produce have increased. In an effort to identify natural antimicrobial agents as fresh produce wash; the effect of essential oils in reducing enteric pathogens on iceberg and romaine lettuce was investigated. Cut lettuce pieces (3 x 2 cm) ...

308

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

Science.gov (United States)

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

309

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

310

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

311

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

312

Classification of Lettuce Nitrogen Levels Based on Image Feature Extraction and Optimization  

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Full Text Available The feature extraction and optimization of lettuce leaf image are the important premise of classification recognition of lettuce nitrogen levels. The lettuce samples of different nitrogen levels were cultivated in soilless cultivation using nitrogen nutrition of different concentrations. When the lettuce leaf images were collected, image features have been extracted, including texture features, shape features and color features. Because of the redundancy of characteristic values, there were influences in the accuracy and efficiency of image recognition. Genetic algorithm was used to optimize 11 eigenvalues and the Principal Component Analysis (PCA dimension reduction method was used to choose 12 principal component feature values whose cumulative contribution rate reached 98.24%. Later, the Support Vector Machine (SVM was used as classifier. The 90 samples were chosen as training samples and the remaining 30 samples were chosen as the test samples. The result shows that, the prediction accuracy of SVM classifier based on genetic algorithm feature optimization reaches 93.33% and that based on PCA features optimization reaches 76.67%. So the genetic algorithm feature optimization is more suitable for lettuce leaf image feature optimization.

Sun Jun

2013-01-01

313

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

314

Sensory quality attributes of lettuce obtained using different harvesting performance systems  

Directory of Open Access Journals (Sweden)

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

315

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

316

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

317

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

318

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

319

Mechanism of protective effect of lettuce against glucose/serum deprivation-induced neurotoxicity.  

Science.gov (United States)

Objectives The present study investigated the protective effect of ethyl acetate fraction of lettuce (Lactuca sativa) against glucose/serum deprivation (GSD)-induced neurotoxicity, a model which simulates neuronal damage during ischemia. Methods Two neuron-like cells, N2a and PC12, were cultivated for 12 hours in GSD condition in the absence or presence of the lettuce fraction. The cell viability, DNA damage, and proapoptotic or antiapoptotic proteins levels were determined using MTT, comet, and immunoblotting assays, respectively. In addition, the intracellular reactive oxygen species and lipid peroxidation levels were measured by fluorimetric methods. Results In both N2a and PC12 cells, GSD condition significantly decreased the cell viability which was accompanied by increased intracellular reactive oxygen species production, lipid peroxidation level, and oxidative DNA damage. All the GSD-induced neurotoxic changes were inhibited by the lettuce fraction. Lettuce also suppressed the elevated Bax and caspase-3 proteins and decreased Bcl-2 induced by GSD in PC12 cells. Discussion The present study revealed that lettuce exerts neuroprotective effect through decrease of oxidative stress and inhibition of proapoptotic pathways. Therefore, it has the potential to be used for the management of ischemia-induced neuronal damage. PMID:24621063

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

2014-01-15

320

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

Scientific Electronic Library Online (English)

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

Ingergleice Machado de Oliveira, Abreu; Ana Maria Resende, Junqueira; José Ricardo, Peixoto; Sebastião Alberto de, Oliveira.

2010-05-01

321

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

322

Changes in macrominerals, trace elements and pigments content during lettuce (Lactuca sativa L.) growth: influence of soil composition.  

Science.gov (United States)

Changes in macrominerals, trace elements and photosynthetic pigments were monitored at 5 stages of lettuce growth. Plants were grown in three experimental agriculture greenhouse fields (A1, A2 and A3). Soil composition was also monitored to understand its influence on lettuce composition. In general, the content of macrominerals, trace elements, chlorophylls and carotenoids decreased during lettuce growth and consequently, high nutritional value was observed at younger stages. A2 lettuces showed an increase of Fe, Al, Cr, V and Pb due to the different soil physicochemical parameters. Multiple linear regression analysis with stepwise variable selection, indicated that soil characteristics, namely, pH(CaCl2) for Fe and Cr, silt and fine-sand for Al and V, OM for Al and Pb, coarse-sand and CEC for Cr, had a key role determining element bioavailability and plant mineral content. Thus, lettuce nutritional value was strongly dependent of growth stage and soil characteristics. PMID:24444982

Pinto, Edgar; Almeida, Agostinho A; Aguiar, Ana A R M; Ferreira, Isabel M P L V O

2014-01-01

323

Lack of internalization of Escherichia coli O157:H7 in lettuce (Lactuca sativa L.) after leaf surface and soil inoculation.  

Science.gov (United States)

Survival and internalization characteristics of Escherichia coli O157:H7 in iceberg, romaine, and leaf lettuce after inoculation of leaf surfaces and soil were determined. A five-strain mixture of E. coli O157:H7 in water and cow manure extract was used as an inoculum for abaxial and adaxial sides of leaves at populations of 6 to 7 log and 4 log CFU per plant. The five strains were individually inoculated into soil at populations of 3 and 6 log CFU/g. Soil, leaves, and roots were analyzed for the presence and population of E. coli O157:H7. Ten (4.7%) of 212 samples of leaves inoculated on the adaxial side were positive for E. coli O157:H7, whereas 38 (17.9%) of 212 samples inoculated on the abaxial side were positive. E. coli O157:H7 survived for at least 25 days on leaf surfaces, with survival greater on the abaxial side of the leaves than on the adaxial side. All 212 rhizosphere samples and 424 surface-sanitized leaf and root samples from plants with inoculated leaves were negative for E. coli O157:H7, regardless of plant age at the time of inoculation or the location on the leaf receiving the inoculum. The pathogen survived in soil for at least 60 days. Five hundred ninety-eight (99.7%) of 600 surface-sanitized leaf and root samples from plants grown in inoculated soil were negative for E. coli O157:H7. Internalization of E. coli O157:H7 in lettuce leaves and roots did not occur, regardless of the type of lettuce, age of plants, or strain of E. coli O157:H7. PMID:19833024

Zhang, Guodong; Ma, Li; Beuchat, Larry R; Erickson, Marilyn C; Phelan, Vanessa H; Doyle, Michael P

2009-10-01

324

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

325

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

326

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

327

Modeling uptake kinetics of cadmium by field-grown lettuce  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-03-15

328

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

329

Erigeron bonariensis: hospedeira alternativa do Lettuce mosaic virus no Brasil  

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Full Text Available O gênero Erigeron (Asteraceae, de plantas da vegetação espontânea, encontra-se amplamente disseminado nas regiões Sul e Sudeste do Brasil, sendo freqüentemente encontrado em lavouras perenes e anuais. Plantas de E. bonariensis com sintoma de mosaico, típico do induzido por vírus, foram coletadas no município de São Paulo e submetidas a análises ao microscópio eletrônico de transmissão, testes biológicos, sorológicos e moleculares. Em cortes ultrafinos do tecido foliar original, observaram-se inclusões tubulares e cata-ventos dispersos no citoplasma. Através de inoculação mecânica, somente Chenopodium amaranticolor, C. quinoa, Nicotiana benthamiana e N. clevelandii foram infetadas. Os resultados obtidos em ELISA foram negativos quando se utilizaram antissoros contra o Turnip mosaic vírus (TuMV e diferentes estirpes do Potato virus Y (PVY, constatando-se relacionamento sorológico com o Lettuce mosaic virus (LMV. Com a utilização de oligonucleotídeos específicos para LMV amplificaram-se fragmentos esperados de aproximadamente 280 pb, que seqüênciados confirmaram a identidade do vírus. A ocorrência do LMV em E. bonariensis, gênero da mesma família botânica da alface (Lactuca sativa, é de grande importância, pois talvez possa atuar como reservatório para infecção de campos de produção de alface. Este é o primeiro relato, no Brasil, de vírus infetando Erigeron sp., o qual só havia sido reportado como hospedeira natural do Bidens mottle virus (BiMoV e do Tomato spotted wilt virus (TSWV nos Estados Unidos.

Chaves Alexandre L. R.

2003-01-01

330

Predicting lettuce canopy photosynthesis with statistical and neural network models  

Science.gov (United States)

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

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

1998-01-01

331

Nutrient absorption and response of lettuce to phosphorus fertilization  

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

Antonio Ismael Inácio Cardoso

2012-09-01

332

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

333

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

334

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

335

Positive effects of temperature and growth conditions on enzymatic and antioxidant status in lettuce plants.  

Science.gov (United States)

The contents of two bioactive compounds (polyphenols and flavonoids) and their antioxidant and enzyme activities were determined in the leaves of six lettuce (Latuca sativa L.) cultivars subjected to 4 different day/night temperatures for 6 weeks. The total polyphenol and anthocyanin contents and the corresponding antioxidant activities were the highest at 13/10°C and 20/13°C, followed by 25/20°C and 30/25°C. The enzymatic activities of polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) were also the highest at low day/night temperatures, but the peroxidase (POD) activity was decreased at low day/night temperatures and increased at high day/night temperatures. The most significant positive correlation existed between anthocyanin content and PPO activity, total polyphenols and their antioxidant activities. The results showed that at relatively low temperatures, lettuce plants have a high antioxidant and enzymatic status. These results provide additional information for the lettuce growers. PMID:21889055

Boo, Hee-Ock; Heo, Buk-Gu; Gorinstein, Shela; Chon, Sang-Uk

2011-10-01

336

Host-induced gene silencing inhibits the biotrophic pathogen causing downy mildew of lettuce.  

Science.gov (United States)

Host-induced gene silencing (HIGS) is an RNA interference-based approach in which small interfering RNAs (siRNAs) are produced in the host plant and subsequently move into the pathogen to silence pathogen genes. As a proof-of-concept, we generated stable transgenic lettuce plants expressing siRNAs targeting potentially vital genes of Bremia lactucae, a biotrophic oomycete that causes downy mildew, the most important disease of lettuce worldwide. Transgenic plants, expressing inverted repeats of fragments of either the Highly Abundant Message #34 (HAM34) or Cellulose Synthase (CES1) genes of B. lactucae, specifically suppressed expression of these genes, resulting in greatly reduced growth and inhibition of sporulation of B. lactucae. This demonstrates that HIGS can provide effective control of B. lactucae in lettuce; such control does not rely on ephemeral resistance conferred by major resistance genes and therefore offers new opportunities for durable control of diverse diseases in numerous crops. PMID:25487781

Govindarajulu, Manjula; Epstein, Lynn; Wroblewski, Tadeusz; Michelmore, Richard W

2014-12-01

337

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

338

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

339

Differences in attachment of Salmonella enterica serovars to cabbage and lettuce leaves.  

Science.gov (United States)

This study investigated the ability of five Salmonella enterica serovars to attach to and colonize intact and cut lettuce (Iceberg, Romaine) and cabbage surfaces. Biofilm formation and attachment of Salmonella serovars to intact and cut leaves were determined. Populations of loosely and strongly attached Salmonella were obtained to calculate the attachment strength (S(R)). Biofilm formation, as determined by microtiter plate assay, varied with strain and growth medium used. Salmonella Tennessee and S. Thompson produced stronger biofilms compared to S. Newport, S. Negev, and S. Braenderup. Biofilm formation was also stronger when Salmonella spp. were grown in diluted TSB (1:10). S. Tennessee, which produced strong biofilms, attached to produce surfaces at significantly higher numbers than the populations of S. Negev. Overall, S. Tennessee displayed more biofilm formation in vitro and attached more strongly to lettuce than other serovars. All Salmonella serovars attached rapidly on intact and cut produce surfaces. Salmonella spp. attached to Romaine lettuce at significantly higher numbers than those attached to Iceberg lettuce or cabbage. Salmonella attached preferentially to cut surface of all produce; however, the difference between Salmonella populations attached to intact and cut surfaces was similar (P>0.05). Salmonella attachment to both intact and cut produce surfaces increased with time. The overall attachment strength of Salmonella was significantly lower on cabbage (0.12) followed by Iceberg (0.23) and Romaine lettuce (0.34). Cabbage, intact or cut, did not support attachment of Salmonella as well as Romaine lettuce. Understanding the attachment mechanisms of Salmonella to produce may be useful in developing new intervention strategies to prevent produce outbreaks. PMID:20226552

Patel, Jitendra; Sharma, Manan

2010-04-30

340

Binding of virus-like particles of Norwalk virus to romaine lettuce veins.  

Science.gov (United States)

Noroviruses (NoV) annually cause millions of cases of gastrointestinal disease in the United States. NoV are associated with raw shellfish outbreaks, particularly oysters, which are thought to bioaccumulate NoV particles during the filter-feeding process. NoV outbreaks, however, have also been known to occur from other common-source food-borne vehicles, such as lettuce, frozen raspberries, and salad. In this study, we evaluated romaine lettuce as a potential vehicle for NoV transmission by testing the binding and distribution of NoV to the surface of romaine. Recombinant Norwalk virus-like particles (rNVLP) applied to the surface of romaine lettuce localized as large clusters primarily on the leaf veins. An extract of romaine lettuce leaves in phosphate-buffered saline (PBS) (romaine extract [RE]) bound rNVLP in a dose-dependent manner. RE did not bind rNVLP by histo-blood group antigens (HBGA), nor was RE competitive with rNVLP binding to porcine gastric mucin. These results suggested that non-HBGA molecules in RE bind rNVLP by a binding site(s) that is different from the defined binding pocket on the virion. Extracts of cilantro, iceberg lettuce, spinach, and celery also bound rNVLP. Samples of each of the vegetables spiked with rNVLP and tested with anti-NVLP antibody revealed by confocal microscopy the presence of rNVLP not only on the veins of cilantro but also throughout the surface of iceberg lettuce. PMID:21037300

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

2010-12-01

341

[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

342

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

343

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  

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

Renate Krause-Sakate

2008-02-01

344

Quality of cut lettuce treated by heat shock: prevention of enzymatic browning, repression of phenylalanine ammonia-lyase activity, and improvement on sensory evaluation during storage.  

Science.gov (United States)

Stored cut lettuce gradually turns brown on the cut section after several days of storage, because cutting induces phenylalanine ammonia-lyase (PAL) activity, the biosynthesis of polyphenol is promoted, and the polyphenols are oxidized by polyphenol oxidase. Here, the effect of heat shock treatment at 50 degrees C for 90 s on the quality of cut lettuce during cold storage was examined. The heat shock treatment significantly repressed the induction of PAL activity and phenolics accumulation in cut lettuce during storage, and prevented the browning of cut lettuce. Ascorbic acid content was not affected by the heat shock treatment. The sensory analysis showed that the organoleptic quality of cut lettuce treated by heat shock was significantly better than that of the control cut lettuce. These results show that heat shock treatment is useful for prolonging the shelf life of cut lettuce. PMID:15056879

Murata, Masatsune; Tanaka, Eriko; Minoura, Emiko; Homma, Seiichi

2004-03-01

345

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  

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Full Text Available Infecções radiculares nos cultivos hidropônicos de alface são frequentes e, na maior parte das vezes, causadas por espécies de Pythium, extremamente bem adaptadas ao ambiente aquático. Este estudo buscou avaliar o potencial patogênico in vitro de Pythium middletonii e P. dissotocum, em quatro cultivares 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.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

2011-03-01

346

Nitrogen fertilization on intercropping of lettuce and rocket Adubação nitrogenada em consórcio de alface e rúcula  

OpenAIRE

The work was carried out at UNESP, Jaboticabal, São Paulo State, Brazil, from September to December 2006, to evaluate the effect of nitrogen fertilization on intercropping of lettuce and rocket. The experiment was conducted in a randomized complete block design, with four replications, treatments being arranged in a 4 x 4 + 2 factorial design. The treatments were the result of a combination of four N rates for lettuce (0, 65, 130 and 195 kg ha-1) and four N rates for rocket (0, 65, 130 and 1...

Barros Ju?nior, Aure?lio P.; Ceci?lio Filho, Arthur B.; Rezende, Bra?ulio Luciano A.; Rq, Diego Po?rto; Prado, Renato M.

2011-01-01

347

The hrp genes of Pseudomonas cichorii are essential for pathogenicity on eggplant but not on lettuce  

OpenAIRE

Pseudomonas cichorii causes necrotic lesions in eggplant and rot in lettuce. Through transposon insertion into P. cichorii strain SPC9018 we produced two mutants, 4-57 and 2-99, that lost virulence on eggplant but not lettuce. Analyses showed that a transposon was inserted into the hrpG gene in 4-57 and the hrcT gene in 2-99. Nucleotide sequences of the hrp genes of SPC9018 are homologous to those of Pseudomonas viridiflava BS group strains. The pathogenicity of 4-57 on eggplant was restored ...

Hojo, Hiroshi; Koyanagi, Makoto; Tanaka, Masayuki; Kajihara, Shigeru; Ohnishi, Kouhei; Kiba, Akinori; Hikichi, Yasufumi

2008-01-01

348

Effect of heat stress on the MDA, proline and soluble sugar content in leaf lettuce seedlings  

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Full Text Available High temperature stress on different varieties of lettuce seedlings in MDA, proline and soluble sugar content were studied. The results were as follows : With the stress temperature, varieties of leaf lettuce seedlings in the MDA, proline and soluble sugar content gradually increased; Different varieties had the most significant difference in 38/33?(d/n. The increase of heat-resistant varieties on proline and soluble sugar content was quick and high, while its increase in MDA content was slow and small.

Yingyan Han

2013-05-01

349

Binding of Virus-Like Particles of Norwalk Virus to Romaine Lettuce Veins?  

OpenAIRE

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

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

2010-01-01

350

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

OpenAIRE

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 thermotoler...

Perondi, P. C.; Souza, A. S.; Barreto, E. S.

2013-01-01

351

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

352

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

353

Condutividade elétrica da solução nutritiva e produção de alface em hidroponia / Electrical conductivity of nutrient solution and hidroponic crisp head lettuce yield  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese A variação da condutividade elétrica da solução nutritiva altera a absorção de água e nutrientes pelas plantas, interferindo no metabolismo e, consequentemente, na produção das mesmas. Este trabalho, conduzido no período de agosto a outubro de 1999, avaliou o efeito da condutividade elétrica (CE) so [...] bre a produção e desenvolvimento de alface americana de cabeça crespa, cultivar Ryder em hidroponia. As tendências de variação da condutividade elétrica do meio nutritivo, durante o desenvolvimento da alface, foram também avaliadas. Foi utilizado o delineamento inteiramente casualizado com seis repetições e três tratamentos, constituídos pelas condutividade elétricas: CE1= 1,46, CE2= 2,46 e CE3= 4,21 (± 0,24) mS cm-1. O diâmetro e altura da cabeça e peso seco da raiz não foram influenciados pelas condutividades elétricas da solução nutritiva. Os maiores pesos do material fresco e seco foram conseguidos com CE 2,46 (± 0,24) mS cm-1. Todos os tratamentos apresentaram a tendência de diminuição da condutividade elétrica, durante o cultivo da alface verificando-se que a condutividade elétrica teve influência sobre as características de produção da alface americana. Abstract in english The levels of electrical conductivity (EC) can alter water and nutrient uptake by plants, influencing their metabolism and yield. This experiment was carried out to verify the effects of EC on the yield and the development of the crisp head lettuce cv. Ryder in hidroponics. The tendency of the elect [...] rical conductivity changes of the nutrient solution during the development of the lettuce was also evaluated. A completely randomized design was used, with six replications and three treataments: EC1= 1.46, EC2= 2.46 and EC3= 4.21 (± 0.24) mS cm-1. Lettuce head diameter and height, and root dry weight were not influenced by EC. The largest fresh and dry weights of heads were obtained for 2.46 (± 0.24) mS cm-1. All treatments had the same tendency of reducing EC during lettuce growth.

Paulo César, Costa; Evanessa B., Didone; Thaís M., Sesso; Kathia Alexandra Lara, Cañizares; Rumy, Goto.

2001-09-01

354

Yield of crisphead lettuce under different amounts of irrigationProdutividade da alface americana submetida a diferentes lâminas de irrigação  

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Full Text Available With the aim of minimizing the difficulties faced by the producers on cultivating the crisphead lettuce (Lactuta sativa L, specifically those related to the lack of technical information about the quantity of water to be applied, a study was made in order to determine the effect of various water depths on crisphead lettuce yielding characteristics. The experiment was carried out at the Universidade Federal de Lavras, from October to December 2008 in greenhouse. A randomized block design with five treatments and four repetitions was applied. The treatments, consisting of the five respective evaporation factors; , 0.30 EVm; 0.60 EVm; 0.90 EVm; 1.20 EVm; 1.50 EVm (evaporate depth, were done according to an evaporated depth of a reduced pan. The results showed that: The maximum commercial yield, 36.5 t ha-1, was estimated by applying a 164.8 mm depth, which corresponded to a water reposition factor of 98 %; the highest water usage efficiency (962.45 kg ha-1 mm-1 was attained when an irrigation depth of 50.10 mm (30% was used.Visando reduzir as dificuldades do produtor no cultivo da alface (Lactuta sativa L americana, especificamente quanto à falta de informações técnicas sobre a quantidade de água a ser aplicada, objetivou-se estudar o efeito de diferentes lâminas de água referentes às características produtivas dessa cultura. O experimento foi realizado na Universidade Federal de Lavras, no período de outubro a dezembro de 2008, em casa de vegetação. O delineamento experimental foi em blocos casualizados, com cinco tratamentos e quatro repetições. Os tratamentos foram cinco fatores de evaporação, correspondentes a 0,30 EVm; 0,60 EVm; 0,90 EVm; 1,20 EVm e 1,50 EVm (lâmina evaporada, baseado na lâmina evaporada de um minitanque. A máxima produtividade comercial, 36,5 t ha-1, foi estimada com a aplicação da lâmina de 164,8 mm, correspondente ao fator de reposição de 98 %, sendo a maior eficiência no uso da água (962,45 kg ha-1 mm-1 obtida com a aplicação da lâmina de irrigação de 50,10 mm, correspondente ao fator de reposição de água de 30%.

Joaquim Alves Lima Junior

2012-12-01

355

Detection of Varicosavirus and Ophiovirus in lettuce associated with lettuce big-vein symptoms in Brazil Detecção de Varicosavirus e Ophiovirus associados à síndrome do espessamento clorótico das nervuras da alface no Brasil  

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Full Text Available During surveys undertaken from 1998 to 2003 in the major vegetable growing areas of the city of São Paulo green belt, lettuce (Lactuca sativa and endive (Cichorium endivia plants were observed, which showed chlorotic thickening of foliar veins, defective growth and, in some cases, failure to form complete heads. Biological and serological [DAS-Enzyme linked immunosorbent assay (Elisa] tests together with electron microscope observations, revealed the presence of Lettuce big-vein virus and Mirafiori lettuce virus, in these plants both responsible for the lettuce big-vein syndrome.Em levantamentos realizados entre 1998 e 2003, nas principais regiões produtoras de alface (Lactuca sativa e escarola (Cichorium endivia no cinturão verde de São Paulo, foram observados sintomas de espessamento de nervuras foliares, clorose, crescimento irregular e ausência de formação da cabeça. Por meio de testes biológicos, DAS-Enzyme linked immunosorbent assay (Elisa e microscopia eletrônica de transmissão constatou-se a presença do Lettuce big-vein associated virus e Mirafiori lettuce virus, responsáveis pela síndrome do espessamento clorótico das nervuras da alface ("lettuce big-vein".

Addolorata Colariccio

2005-08-01

356

Detection of Varicosavirus and Ophiovirus in lettuce associated with lettuce big-vein symptoms in Brazil / Detecção de Varicosavirus e Ophiovirus associados à síndrome do espessamento clorótico das nervuras da alface no Brasil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Em levantamentos realizados entre 1998 e 2003, nas principais regiões produtoras de alface (Lactuca sativa) e escarola (Cichorium endivia) no cinturão verde de São Paulo, foram observados sintomas de espessamento de nervuras foliares, clorose, crescimento irregular e ausência de formação da cabeça. [...] Por meio de testes biológicos, DAS-Enzyme linked immunosorbent assay (Elisa) e microscopia eletrônica de transmissão constatou-se a presença do Lettuce big-vein associated virus e Mirafiori lettuce virus, responsáveis pela síndrome do espessamento clorótico das nervuras da alface ("lettuce big-vein"). Abstract in english During surveys undertaken from 1998 to 2003 in the major vegetable growing areas of the city of São Paulo green belt, lettuce (Lactuca sativa) and endive (Cichorium endivia) plants were observed, which showed chlorotic thickening of foliar veins, defective growth and, in some cases, failure to form [...] complete heads. Biological and serological [DAS-Enzyme linked immunosorbent assay (Elisa)] tests together with electron microscope observations, revealed the presence of Lettuce big-vein virus and Mirafiori lettuce virus, in these plants both responsible for the lettuce big-vein syndrome.

Addolorata, Colariccio; Alexandre L.R., Chaves; Marcelo, Eiras; César M., Chagas; Piero, Roggero.

2005-08-01

357

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  

Directory of Open Access Journals (Sweden)

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

358

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

359

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.

2004-02-01

360

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

Science.gov (United States)

The main objective of a life support system for space missions is to supply a crew with food, water and oxygen, and to eliminate their wastes. The ultimate goal is to achieve the highest degree of closure of the system using controlled processes offering a high level of reliability and flexibility. Enhancement of closure of a biological life support system (BLSS) that includes plants relies on increased regeneration of plant waste, and utilization of solid and liquid human wastes. Clearly, the robustness of a BLSS subjected to stress will be substantially determined by the robustness of the plant components of the phototrophic unit. The aim of the present work was to estimate the heat resistance of two plants (wheat and lettuce) grown on human wastes. Human exometabolites mineralized by hydrogen peroxide in an electromagnetic field were used to make a nutrient solution for the plants. We looked for a possible increase in the heat tolerance of the wheat plants using changes in photosynthetically active radiation (PAR) intensity during heat stress. At age 15 days, plants were subjected to a rise in air temperature (from 23 ± 1 °C to 44 ± 1 °?) under different PAR intensities for 4 h. The status of the photosynthetic apparatus of the plants was assessed by external ??2 gas exchange and fluorescence measurements. The increased irradiance of the plants during the high temperature period demonstrated its protective action for both the photosynthetic apparatus of the leaves and subsequent plant growth and development. The productivity of the plants subjected to temperature changes at 250 W m-2 of PAR did not differ from that of controls, whereas the productivity of the plants subjected to the same heat stress but in darkness was halved.

Ushakova, Sofya A.; Tikhomirov, Alexander A.; Shikhov, Valentin N.; Gros, Jean-Bernard; Golovko, Tamara K.; Dal'ke, Igor V.; Zakhozhii, Ilya G.

2013-06-01

361

Water  

Science.gov (United States)

... to drink more water Other drinks How much water do you need? top Water is very important, ... you probably need more water. What about bottled water? top Some people like bottled water for its ...

362

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.

363

Development of a simple extraction and oxidation procedure for the residue analysis of imidacloprid and its metabolites in lettuce using gas chromatography.  

Science.gov (United States)

Simple extraction and optimised oxidation procedures were developed for the determination of the total residues of imidacloprid and its metabolites (containing the 6-chloropicolyl moiety) in lettuce using a gas chromatography-micro electron capture detector (GC-?ECD). Samples were extracted with acetonitrile, and the extract was then evaporated. The remaining residues were dissolved in water and oxidised with potassium permanganate to yield 6-chloronicotinic acid (6-CAN). The acid residues were further dissolved in n-hexane:acetone (8:2, v/v) and then silylated with MSTFA (N-methyl-N-(trimethylsilyl)trifluoroacetamide) to 6-chloronicotinic acid trimethylsilyl ester. Calibration curves were linear over the concentration ranges (0.025-5 ?g mL(-1)) with a determination coefficient (r(2)) of 0.991. The limits of detection and quantification were 0.015 and 0.05 mg kg(-1), respectively. Recoveries at two fortification levels ranged between 72.8% and 108.3% with relative standard deviation (RSD) lower than 8%. The method was effective, and sensitive enough to determine the total residues of imidacloprid and its metabolites in field-incurred lettuce samples. The identity of the analyte was confirmed using gas chromatography-tandem mass spectrometry (GC-MS/MS). PMID:24262575

Ko, Ah-Young; Rahman, Md Musfiqur; Abd El-Aty, A M; Jang, Jin; Park, Jong-Hyouk; Cho, Soon-Kil; Shim, Jae-Han

2014-04-01

364

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

365

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

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

366

Romaine lettuce latex deters feeding of banded cucumber beetle: a vehicle for deployment of biochemical defenses  

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Latex is widely found among plant species and is known to play a defensive role against certain herbivores. Two romaine lettuce cultivars, ‘Valmaine’ (resistant) and ‘Tall Guzmaine’ (susceptible) were selected to study the potential of latex as a defense mechanism against the banded cucumber beetle,...

367

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

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

368

The hrp genes of Pseudomonas cichorii are essential for pathogenicity on eggplant but not on lettuce.  

Science.gov (United States)

Pseudomonas cichorii causes necrotic lesions in eggplant and rot in lettuce. Through transposon insertion into P. cichorii strain SPC9018 we produced two mutants, 4-57 and 2-99, that lost virulence on eggplant but not lettuce. Analyses showed that a transposon was inserted into the hrpG gene in 4-57 and the hrcT gene in 2-99. Nucleotide sequences of the hrp genes of SPC9018 are homologous to those of Pseudomonas viridiflava BS group strains. The pathogenicity of 4-57 on eggplant was restored by transformation with an hrpF operon, originating from either SPC9018 or the BS group member P. viridiflava strain 9504 (Pv9504). These data suggested the involvement of hrp genes in the pathogenicity of SPC9018 on eggplant, and functional conservation of hrpF operons between SPC9018 and Pv9504. Both the hrpS mutant and the hrpL mutant were unable to cause necrotic lesions on eggplant leaves but retained their pathogenicity against lettuce. These results suggest that the pathogenicity of P. cichorii is hrp-dependent in eggplant, but not in lettuce. PMID:18832299

Hojo, Hiroshi; Koyanagi, Makoto; Tanaka, Masayuki; Kajihara, Shigeru; Ohnishi, Kouhei; Kiba, Akinori; Hikichi, Yasufumi

2008-10-01

369

Phosphomannose isomerase gene for selection in lettuce (Lactuca sativa L.) transformation.  

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A positive selection system using phosphomannose isomerase was employed for Agrobacterium tumefaciens mediated transformation of lettuce (Lactuca sativa L. var. 'Achát'). It was shown that the mannose-based selection system works very well with the lettuce genotype used, reaching up to 25% transformation efficiency on the medium with 20 g/L mannose and 20 g/L sucrose. The best transformation efficacy with the commonly-used kanamycin at 100 mg/L as a selection agent was 21%. Southern blot analyses of thirteen chosen mannose-resistant regenerants revealed that some of them have clonal origin, about one-half harbour a single T-DNA copy and one plant contains an incomplete T-DNA segment with only the left part of T-DNA with the pmi gene present in the genomic DNA. The following Northern analysis showed transcriptional activity of the introduced pmi gene in all plants analysed with very high differences in the level of pmi specific mRNA. The results demonstrate that both mannose and kanamycin provide comparable transformation efficiencies in our lettuce genotype. An alternative selection method with mannose as a selection agent is now available for lettuce transgenosis. PMID:20234883

Bríza, Jindrich; R?zicková, Nina; Niedermeierová, Hana; Dusbábková, Jana; Vlasák, Josef

2010-01-01

370

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

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

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

2006-02-01

371

Iodine effects on phenolic metabolism in lettuce plants under salt stress.  

Science.gov (United States)

Iodine, applied as iodate in biofortification programs (at doses of ?80 ?M), has been confirmed to improve the foliar biomass, antioxidant response, and accumulation of phenol compounds in lettuce plants. The changes in phenolic compounds induced by the iodate application appear to have functional consequences in the response of salt-stressed plants. Thus, the aim of the present study was to determine whether the application of iodate can improve the response of severe salinity stress and whether the resistance can be attributed to the phenolic metabolism in lettuce ( Lactuca sativa cv. Philipus), a glycophyte cultivated for food and consumed year round. In this work, the application of iodate, especially at 20 and 40 ?M, in lettuce plants under salinity stress (100 mM NaCl) exerted a significantly positive effect on biomass and induced higher activity in the enzymes shikimate dehydrogenase and phenylalanine ammonia-lyase as well as the lower MW phenol-degrading enzyme polyphenol oxidase. This increased hydroxycinnamic acids and derivatives in addition to total phenols, which appear to act as protective compounds against salinity. This study reveals that in agricultural areas affected by this type of stress, the application of iodate may be an effective strategy, as it not only improves lettuce plant growth but also supplements the human diet with phenolic compounds and the trace element iodine. PMID:23445402

Blasco, Begoña; Leyva, Rocio; Romero, Luis; Ruiz, Juan Manuel

2013-03-20

372

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

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

373

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

Science.gov (United States)

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

374

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

Science.gov (United States)

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

375

Expression of gamma-tocopherol methyltransferase transgene improves tocopherol composition in lettuce (Latuca sativa L.).  

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A cDNA encoding gamma-tocopherol methyltransferase (gamma-TMT) from Arabidopsis thaliana was overexpressed in lettuce (Latuca sativa L.) to improve the tocopherol composition. Seven lines of lettuce (T0) containing the gamma-TMT transgene were produced by Agrobacterium-mediated transformation. The inheritance and expression of the transgene were confirmed by DNA and RNA gel blot analyses as well as quantification of tocopherols and gamma-TMT activities. The ratio of alpha-/gamma-tocopherol content (TR) varied from 0.6 to 1.2 in non-transformed plants, while the T0 plants had ratios of 0.8 to 320. The ratio ranged from 0.4 to 544 in 41 T1 progenies of the T0 transgenic line gTM3, and the phenotypic segregation indicated monogenic inheritance of the transgene (i.e., 3:1 = dominant:wild-type classes). There was a tight relationship between the TR phenotype and gamma-TMT activity, and enzyme activities were affected by the copy number and transcript levels of the transgene. The TR phenotype was stably expressed in T2 progenies of T1 plants. The results from this study indicated that a stable inheritance and expression of Arabidopsis gamma-TMT transgene in lettuce results in a higher enzyme activity and the conversion of the gamma-tocopherol pool to alpha-tocopherol in transgenic lettuce. PMID:15750335

Cho, Eun Ae; Lee, Chong Ae; Kim, Young Soo; Baek, So Hyeon; de los Reyes, Benildo G; Yun, Song Joong

2005-02-28

376

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

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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...

377

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

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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

378

Phosphorus levels in soil and lettuce production due to phosphorus fertilization  

Directory of Open Access Journals (Sweden)

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

379

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

380

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...