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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A revision of the genus Lactuca (Compositae: Lactuceae) in the Great Plains

Dille, David P January 2011 (has links)
Digitized by Kansas Correctional Industries
2

Contaminación de Lactuca sativa “lechuga” con formas evolutivas de parásitos intestinales que se expenden como alimento en los establecimientos de consumo público del Distrito de Ciudad Nueva – Tacna

Castro Sánchez, Hevelin Velinea 04 April 2014 (has links)
El presente estudio está inmerso en el campo de la Parasitología, el cual tuvo como objetivo determinar el grado de contaminación de parásitos intestinales en verduras crudas expendidas en establecimientos de consumo público de alimentos del distrito de Ciudad Nueva – Tacna, entre enero y noviembre de 2011; donde se recolectaron al azar 131 muestras de ensaladas de Lactuca sativa “lechuga” de comedores populares, restaurantes, cebicherías, pollerías y sandwcherías dentro de la zona de estudio, las mismas que fueron procesadas y analizadas por el método de Faust, método directo de observación y por la técnica de coloración de Ziehl Neelsen modificado, en el laboratorio de Parasitología de la Facultad de Ciencias de la Universidad Nacional, encontrándose que 61 muestras dieron positivo a la presencia de alguna forma parasitaria, con un porcentaje de contaminación parasitaria de 46,56 %. Se observaron diferentes especies parasitarias, pertenecientes al Sub Reino Protozoa, Entamoeba coli fue el de mayor prevalencia con un 56,38 %, seguido por Cryptosporidium parvum con un 34,04 % y Giardia lamblia con un 9,75 %.
3

Resistência de cultivares diferenciadoras do míldio da alface a nematoides de galha / Resistance of lettuce downy mildew's differential cultivars to root-knot nematodes

Vidal, Roberta Luiza 16 January 2018 (has links)
Submitted by ROBERTA LUIZA VIDAL null (robertalvidal@gmail.com) on 2018-01-24T18:28:24Z No. of bitstreams: 1 Dissertação_Roberta_Luiza_Vidal.pdf: 1450601 bytes, checksum: edd16eed2fa6fd6a4838da64795991c7 (MD5) / Approved for entry into archive by Karina Gimenes Fernandes null (karinagi@fcav.unesp.br) on 2018-01-26T11:14:58Z (GMT) No. of bitstreams: 1 vidal_rl_me_jabo.pdf: 1409244 bytes, checksum: 56ecd2ad1616f277b1725ec6899dbc3e (MD5) / Made available in DSpace on 2018-01-26T11:14:58Z (GMT). No. of bitstreams: 1 vidal_rl_me_jabo.pdf: 1409244 bytes, checksum: 56ecd2ad1616f277b1725ec6899dbc3e (MD5) Previous issue date: 2018-01-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Devido ao potencial danoso e existência de inúmeras raças de míldio da alface (Bremia lactucae Regel), vários países realizam a identificação e monitoramento destas raças através do uso de cultivares diferenciadoras de alface. A identificação de resistência a outras doenças importantes nestas cultivares seria de grande valia para o melhoramento da alface, permitindo a seleção simultânea para doenças. Dentre os patógenos de solo, destacam-se os nematoides de galha (Meloidogyne spp.) por seus danos e dificuldade de controle. O presente trabalho teve como objetivo avaliar a resposta das cultivares diferenciadoras de míldio (C-Set) à M. javanica e M. incognita. O experimento foi conduzido em delineamento inteiramente casualizado, com oito repetições e população inicial de 1.000 ovos e juvenis. As avaliações foram realizadas pelos critérios fator de reprodução e índice de reprodução, 75 dias após a inoculação. Os dados foram submetidos à análise de variância e as médias comparadas pelo teste de Scott-Knott a 5% de probabilidade. Todos as cultivares são suscetíveis a M. incognita. As cultivares Argelès, Kibrille, Balesta, Colorado, Design, Bartoli e NunDm15 são classificados como resistentes a M. javanica pelo fator de reprodução e podem ser explorados para seleção simultânea ao míldio e a esta espécie de nematoide. / Due to the harmful potential and existence of numerous races of lettuce downy mildew (Bremia lactucae Regel), several countries perform the identification and monitoring of these races through the use of differential lettuce cultivars. The identification of resistance to other important diseases in these cultivars would be of great value for the lettuce’s breeding, allowing the simultaneous selection for diseases. Among the soil pathogens, the most important are the root-knot nematodes (Meloidogyne spp.) due to their damage and difficulty of control. In the present work it was evaluated the response of these differential cultivars (C-Set) to M. javanica and M. incognita. The experiment was conducted in a completely randomized design, with eight replications and initial population of 1.000 eggs and juveniles. The evaluations were performed by the criteria of reproduction factor and reproduction index, 75 days after inoculation. Data were submitted to analysis of variance and the means were compared by Scott-Knott test at 5% probability. All cultivars are susceptible to M. incognita. The cultivars Argelès, Kibrille, Balesta, Colorado, Design, Bartoli and NunDm15 are classified as resistant to M. javanica by the reproduction factor and can be exploited for simultaneous selection to mildew and this species of nematode.
4

Microclima na produção de alface hidropônica em ambiente protegido utilizando telas de sombreamento como subcobertura / Microclimate hydroponic lettuce production in greenhouse shading using screens as subcover

Sales, Francisco Alexandre de Lima January 2012 (has links)
SALES, Francisco Alexandre de Lima. Microclima na produção de alface hidropônica em ambiente protegido utilizando telas de sombreamento como subcobertura. 2012. 96 f. Dissertação (Mestrado em engenharia agrícola)- Universidade Federal do Ceará, Fortaleza-CE, 2012. / Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-06-21T19:50:34Z No. of bitstreams: 1 2012_dis_falsales.pdf: 1966477 bytes, checksum: c3c95147261d4aba1b9c5326c3aae021 (MD5) / Approved for entry into archive by José Jairo Viana de Sousa (jairo@ufc.br) on 2016-07-21T20:14:01Z (GMT) No. of bitstreams: 1 2012_dis_falsales.pdf: 1966477 bytes, checksum: c3c95147261d4aba1b9c5326c3aae021 (MD5) / Made available in DSpace on 2016-07-21T20:14:01Z (GMT). No. of bitstreams: 1 2012_dis_falsales.pdf: 1966477 bytes, checksum: c3c95147261d4aba1b9c5326c3aae021 (MD5) Previous issue date: 2012 / The adequacy of the microclimate of greenhouses to the needs of crop, has become a very important factor for the proper development of protected crops, times and in certain internal temperatures rise and may reduce photosynthesis.For this alternative technologies can be used to suit the needs of temperatures cultures, such as the use of shading screens, particularly for reducing the temperature in the warmer periods of the day. Therefore, the objective of this study was to evaluate the effect of different types of shading screens installed inside the greenhouses, just below the roof, on the growth of two varieties of lettuce crisp (Marianne and Veronica), in a production system in NFT hydroponic (Laminar Flow Technique). The experiment was conducted in greenhouses covered with LDPE film of 150 micron, which had the following treatments: environment without using the screen as undercoverage (ST), ambient thermal reflector screen as undercoverage (TC), Environment shade cloth as black undercoverage (TP) and environment as undercoverage red screen (TV). To assess the environmental changes caused by the use of LDPE film and screens were installed in each greenhouse and an outdoor thermo-hygrometer data loggers that recorded the environmental variables (temperature and relative humidity) every 30 minutes throughout the period of Experimental. Subsequently, we calculated the accumulated degree days for each environment. To analyze changes in patterns of plant response to different environmental conditions, there were five samplings during the experiment, and randomly collected twenty plants per treatment. The plants were removed from the benches replaced by others coming from the stands replacement. After collecting the plants, they were brought to the laboratory for measurement of dry weight of root, stem and leaves, and leaf area. This information was used for estimating of variable morphological. The results indicated that the use of screens as undercoverage affected the environment inside the greenhouse, especially temperature and relative humidity, where the use of thermal reflector and black screens reduced the maximum temperature at 4.7 and 3.6 ° C, respectively, with the environment that was not on screen as undercoverage (ST). Regarding the accumulation of degree days, the environment and TV ST showed very similar behavior, however environments CT and VT had a lower thermal accumulation in relation to TS and TV. As for the morphological changes caused by environmental changes, we determined that the use of thermal reflector screens and black influenced, positively, the number of leaves, leaf number larger than 10 cm and the leaf area index. It was also observed that the variables, number of leaves, leaf number larger than 10 cm, leaf area index, absolute growth rate and net assimilation rate were adjusted, with high levels of determination, a sigmoidal equation with three parameters. While the variables, leaf weight, leaf area ratio, specific leaf area and relative growth rate showed a better fit 3rd degree polynomial. In general, the use of thermal reflector and black screens provided an improvement of some key factors to trade in plants (number of leaves greater than 10 cm and LAI), however, it is not possible to say that these conditions are significant for all seasons , making it necessary more study at other times of the year. / A adequação do microclima das estufas às necessidades das culturas tornou-se um fator de suma importância para o bom desenvolvimento das culturas no cultivo protegido, sendo que em determinados horários as temperaturas internas se elevam podendo reduzir a fotossíntese. Para isso, podem ser utilizadas tecnologias alternativas que adequem as temperaturas as necessidades das culturas, tais como o uso de telas de sombreamento, principalmente para a redução da temperatura nos períodos mais quentes do dia. Sendo assim, o objetivo deste trabalho foi avaliar o efeito de diferentes tipos de telas de sombreamento instaladas internamente nas estufas, logo abaixo da cobertura, sobre o crescimento de duas variedades de alface do tipo crespa (Marianne e Verônica), em um sistema de produção hidropônico em NFT (Técnica de Fluxo Laminar). O experimento foi conduzido em estufas cobertas com filme PEBD de 150 µm, que apresentavam os seguintes tratamentos: ambiente sem uso de tela como subcobertura (ST), ambiente com tela termorrefletora como subcobertura (TC), ambiente com tela de sombreamento preta como subcobertura (TP) e ambiente com tela vermelha como subcobertura (TV). Para avaliar a modificação ambiental ocasionada pelo uso do filme PEBD e das telas, foram instalados, em cada estufa e no ambiente externo, termo-hidrômetros data loggers que registravam as variáveis ambientais (temperatura e umidade relativa) a cada 30 minutos durante todo o período experimental. Posteriormente, foram calculados os graus dia acumulados de cada ambiente. Para analisar as alterações nos padrões de resposta das plantas aos diferentes ambientes de cultivo, foram realizadas cinco coletas de plantas durante o período do experimento, sendo coletadas ao acaso, vinte plantas por tratamento. As plantas retiradas das bancadas eram repostas por outras vindas das bancadas de reposição. Após a coleta das plantas, as mesmas eram levadas ao laboratório para realização das medições de peso seco de raiz, caule e folhas, e da área foliar. Essas informações foram utilizadas para estimar as variáveis morfológicas. Os resultados indicaram que o uso das telas como subcobertura afetou o ambiente no interior das estufas, principalmente a temperatura e a umidade relativa do ar, onde o uso das telas termorrefletora e preta reduziu a temperatura máxima em 4,7 e 3,6ºC, respectivamente, com relação ao ambiente que não usava tela como subcobertura (ST). Em relação ao acúmulo de graus dia, o ambiente ST e TV apresentaram comportamentos bem similares, contudo os ambientes TC e TP apresentaram um menor acúmulo térmico em relação a ST e TV. Quanto às alterações morfológicas ocasionadas pelas modificações ambientais foi possível constatar que o uso das telas termorrefletora e preta influenciou de forma positiva o número de folhas, o número de folhas maiores que 10 cm e o índice de área foliar. Também foi possível observar que as variáveis, número de folhas, número de folhas maiores que 10 cm, índice de área foliar, taxa de crescimento absoluto e taxa de assimilação líquida ajustaram-se, com elevados índices de determinação, a uma equação sigmoidal com três parâmetros. Enquanto que as variáveis, razão de peso foliar, razão de área foliar, área foliar específica e taxa de crescimento relativo apresentaram ajuste polinomial de 3º grau. De modo geral, o uso das telas termorrefletora e preta proporcionou uma melhoria de alguns fatores primordiais ao comércio das plantas (número de folhas maiores que 10 cm e IAF), porém não se pode afirmar que tais condições sejam significativas para todas as épocas do ano, fazendo-se necessários mais estudos em outras épocas do ano.
5

Understanding 2,4-d resistance in prickly lettuce (Lactuca serriola L.) and evaluating chemical fallow systems for the inland PNW

Riar, Dilpreet Singh. January 2009 (has links) (PDF)
Thesis (Ph. D.)--Washington State University, December 2009. / Title from PDF title page (viewed on Feb. 8, 2010). "Department of Crop and Soil Sciences." Includes bibliographical references.
6

Ecological effects of Ulva lactuca L. in Avon-Heathcote Estuary

Murphy, Gerry January 2006 (has links)
Macroalgal blooms are increasing world-wide and have negative effects on benthic invertebrates and sediments. These include loss of species diversity and development of hostile sediment environments. This thesis considers ecological effects of Ulva lactuca L., and its mechanical removal on benthic invertebrates and sediments in Avon-Heathcote Estuary, New Zealand. Benthic communities comprised 34 species from 12 groups recorded from seven sites during seasonal general surveys. Dominant groups at each site were Gastropoda and Bivalvia. The most abundant species were Austrovenus stutchburyi, Micrelenchus tenebrosus and Amphibola crenata. Community composition varied significantly between sites, and there were significant site-specific differences in abundances of most species between winter and summer. U. lactuca had the greatest seasonal variation. Several species correlated with U. lactuca biomass, and the strength of correlation for different species varied between sites. There were seasonal changes in sediment physico-chemical variables between sites with greatest change in the silt/clay fraction. The sediment variables silt/clay fraction, dissolved oxygen and temperature correlated with seasonal changes of patterns in benthic community assemblages. A similar study was carried out by Bressington in 2003. In both studies, Bivalvia and Gastropoda were the most abundant groups, with Gastropoda having a higher, and Bivalvia a lower, proportion in the present study compared with 2003. Summer communities were significantly different between the two studies. Compared with 2003 there were higher percentages of sediment pore water and volatile solids present in 2005. Experimental removal of U. lactuca was conducted by mechanical broom at two sites: an open, exposed central sand flat, and McCormacks Bay, a shallow, sheltered mud flat. Removing U. lactuca had several immediate effects. These included a significant decrease in abundance of mobile epifauna (Micrelenchus tenebrosus and Zeacumantus subcarinatus) and an increase in abundance of infauna, including Arthritica bifurca and Austrovenus stutchburyi. There was no effect of U. lactuca removal on Austrovenus stutchburyi condition and 46 days following removal, invertebrate abundances approached pre-removal levels at each site. U. lactuca removal also caused short-term increases in dissolved oxygen and temperature of pore water. The greatest visual impact of removing U. lactuca was to sediments in McCormacks Bay from trampling. It was concluded that the variables having the greatest effect on seasonal species distribution and abundance at each site were temperature and sediment grain size. Differences between the present study and the study in 2003 were due to differences in sampling procedure mainly due to the two different quadrat sizes. Greater accuracy in representing long-term changes in ecosystems would be achieved by using standard sampling protocols. Removal of U. lactuca by mechanical broom was effective and had low impact on benthic invertebrates and physico-chemical variables, but it should be used only in sandy habitats because of severe disturbance to soft-sediment environments. Options for management and control of U. lactuca in Avon-Heathcote Estuary are discussed.
7

Studies on the induction of acid phosphatase in response to phosphorus deficiency in Ulva lactuca L. (Ulvales, Cholrophyta)

Tsai, Pei-Fen 24 June 2003 (has links)
The roles of phosphorus (P) starvation on the induction of intracellular acid phosphatase (ACP; EC 3.1.3.2) activity have been studied in a marine macroalga Ulva lactuca L. In comparison to creasy and dark green appearance in P-sufficient thalli (100 mM NaH2PO4), P-starved thalli (1 mM NaH2PO4) showed less crease and light green appearance. On exposure to 1 mM NaH2PO4, the growth rate, the contents of SRP, PP and P, and tissue C:P and N:P molar ratio decreased at day 3 and the contents of SNRP, TSP and polyphosphate decreased immediately. Intracellular ACP activity increased at day 3 after exposure to 1 mM NaH2PO4 and reached 16 folds of P-sufficient thalli at day 14, while extracellular alkaline phosphatase (AP; EC 3.1.3.1) activity increased at day 2 and reached the plateau after 4 days. Activity staining both on Native PAGE and IEF gel showed the induction of 10 and 9 ACP isoenzymes, respectively. Changes in intracellular ACP and extracellular AP activities were negatively correlated with SRP, SNRP, PP and P contents. After transferred to 100 mM NaH2PO4, the growth rate of 10 day-starvated thalli recovered after 5 days, the contents of SRP¡BSNRP¡BTSP and P, and the C:P and N:P molar ratio recovered to the level of P-sufficient thalli at day 1. When recovered to 100 mM NaH2PO4, extracellular AP activity of 10 day-starvated thalli decreased at day 2 and reached the minimum after day 8, while intracellular ACP activity decreased at day 3 and reached the minimum after day 8. The analog of Pi, Phi (1 mM) inhibited the intracellular ACP and extracellular AP activities induced by P swtarvation. The results of present investigation show that ACP has a role in the enhancement of P availability in U. lactuca via the enzymatically degradation of polyphosphates and organic P when suffers P deficiency.
8

Biology and management of Fusarium wilt of lettuce

Matheron, Michael E. 08 1900 (has links)
3 pp. / This publication provides information on the development and management of Fusarium wilt of lettuce. Topics covered include the characteristics of the plant pathogen, disease development, and disease management considerations.
9

Ecological effects of Ulva lactuca L. in Avon-Heathcote Estuary

Murphy, Gerry January 2006 (has links)
Macroalgal blooms are increasing world-wide and have negative effects on benthic invertebrates and sediments. These include loss of species diversity and development of hostile sediment environments. This thesis considers ecological effects of Ulva lactuca L., and its mechanical removal on benthic invertebrates and sediments in Avon-Heathcote Estuary, New Zealand. Benthic communities comprised 34 species from 12 groups recorded from seven sites during seasonal general surveys. Dominant groups at each site were Gastropoda and Bivalvia. The most abundant species were Austrovenus stutchburyi, Micrelenchus tenebrosus and Amphibola crenata. Community composition varied significantly between sites, and there were significant site-specific differences in abundances of most species between winter and summer. U. lactuca had the greatest seasonal variation. Several species correlated with U. lactuca biomass, and the strength of correlation for different species varied between sites. There were seasonal changes in sediment physico-chemical variables between sites with greatest change in the silt/clay fraction. The sediment variables silt/clay fraction, dissolved oxygen and temperature correlated with seasonal changes of patterns in benthic community assemblages. A similar study was carried out by Bressington in 2003. In both studies, Bivalvia and Gastropoda were the most abundant groups, with Gastropoda having a higher, and Bivalvia a lower, proportion in the present study compared with 2003. Summer communities were significantly different between the two studies. Compared with 2003 there were higher percentages of sediment pore water and volatile solids present in 2005. Experimental removal of U. lactuca was conducted by mechanical broom at two sites: an open, exposed central sand flat, and McCormacks Bay, a shallow, sheltered mud flat. Removing U. lactuca had several immediate effects. These included a significant decrease in abundance of mobile epifauna (Micrelenchus tenebrosus and Zeacumantus subcarinatus) and an increase in abundance of infauna, including Arthritica bifurca and Austrovenus stutchburyi. There was no effect of U. lactuca removal on Austrovenus stutchburyi condition and 46 days following removal, invertebrate abundances approached pre-removal levels at each site. U. lactuca removal also caused short-term increases in dissolved oxygen and temperature of pore water. The greatest visual impact of removing U. lactuca was to sediments in McCormacks Bay from trampling. It was concluded that the variables having the greatest effect on seasonal species distribution and abundance at each site were temperature and sediment grain size. Differences between the present study and the study in 2003 were due to differences in sampling procedure mainly due to the two different quadrat sizes. Greater accuracy in representing long-term changes in ecosystems would be achieved by using standard sampling protocols. Removal of U. lactuca by mechanical broom was effective and had low impact on benthic invertebrates and physico-chemical variables, but it should be used only in sandy habitats because of severe disturbance to soft-sediment environments. Options for management and control of U. lactuca in Avon-Heathcote Estuary are discussed.
10

Ecological effects of Ulva lactuca L. in Avon-Heathcote Estuary : a thesis submitted in partial fulfilment of the requirements for the degree of Masters [i.e. Master] of Science in Zoology at the University of Canterbury, New Zealand /

Murphy, Gerry, January 2006 (has links)
Thesis (M. Sc.)--University of Canterbury, 2006. / Typescript (photocopy). Includes bibliographical references (leaves 116-138). Also available via the World Wide Web.

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