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Photosynthetic response of poikilochlorophyllous desiccation-tolerant Pleurostima purpurea (Velloziaceae) to dehydration and rehydration

Aidar, S.T.; Meirelles, Sergio Tadeu; Oliveira, Ricardo Ferraz de
Fonte: Prague Publicador: Prague
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
37.07%
The poikilochorophyllous, desiccation-tolerant (PDT) angiosperm, Pleurostima purpurea, normally occurs in less exposed rock faces and slightly shady sites. Our aim was to evaluate the light susceptibility of the photosynthetic apparatus during dehydration-rehydration cycle in P. purpurea. In a controlled environment, the potted plants were subjected to water deficit under two different photosynthetic photon flux densities [PPFD, 100 and 400 µmol(photon) m–2 s–1]. In the higher PPFD, net photosynthetic rate (PN) become undetectable after stomata closure but photochemical efficiency of photosystem II, electron transport rate, and photochemical quenching coefficient were maintained relatively high, despite a partial decrease. The photochemical activity was inhibited only after the complete loss of chlorophylls, when leaf relative water content dropped below 72% and total carotenoids reached maximal accumulation. Nonphotochemical energy dissipation increased earlier in response to dehydration under higher PPFD. PN and photochemical activity were fully recovered after rehydration under both light treatments. Our results suggested that the natural occurrence of P. purpurea should not be restricted by the light intensity during the complete desiccation-rehydration cycles.; Fundação de Amparo à Pesquisa do Estado de São Paulo; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Tolerância à dessecação em Pleurostima purpurea (Velloziaceae): trocas gasosas, pigmentos fotossintéticos e conteúdo relativo de água foliar; Desiccation tolerance in Pleurostima purpurea (Velloziaceae): gas exchanges, photosynthetic pigments and leaf relative water content

Aidar, Saulo de Tarso
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/12/2005 PT
Relevância na Pesquisa
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Pleurostima purpurea (Velloziaceae) é uma espécie rupícola encontrada em afloramentos rochosos do estado do Rio de Janeiro, sudeste do Brasil. Por apresentar notável capacidade de tolerar a dessecação vegetativa, este estudo teve o intuito de esclarecer detalhes sobre a estratégia ecofisiológica utilizada por tais plantas frente à desidratação do ambiente e as vantagens associadas ao processo. Para tanto foi analisada a dinâmica de trocas gasosas, o conteúdo de pigmentos fotossintéticos e o conteúdo relativo de água de tecidos foliares durante os processos de dessecação e reidratação de indivíduos adultos cultivados. Comportaram-se como homeohídricas típicas economizadoras de água sob condição de seca moderada que, quando agravada, assumiram o comportamento de pecilohídricas e peciloclorófilas. A suspensão da irrigação provocou o fechamento estomático sob conteúdo relativo de água foliar acima de 90%, levando a restrições sobre a transpiração e assimilação líquida de carbono até o estabelecimento da anabiose. Durante este processo, houve um atraso na diminuição do CRAfoliar em relação ao CRAplanta-solo. A degradação das clorofilas acompanhou a diminuição do CRAfoliar, o qual alcançou o valor médio mínimo de 17% sem incorrer na abscisão das folhas...

Desiccation effects on germination and vigor of King palm seeds

Martins, Cibele C.; Bovi, Marilene L. A.; Nakagawa, João
Fonte: Associação Brasileira de Horticultura Publicador: Associação Brasileira de Horticultura
Tipo: Artigo de Revista Científica Formato: 88-92
ENG
Relevância na Pesquisa
36.92%
Determinou-se a tolerância ao dessecamento de sementes de Archontophoenix alexandrae (Wendl. & Drude) e identificou-se o teste de vigor mais sensível para avaliar a deterioração de sementes nessa espécie. Frutos maduros foram colhidos na coleção de palmeiras do Instituto Agronômico em Campinas. Os frutos despolpados foram transportados em embalagem impermeável para a UNESP em Botucatu, onde as sementes foram secas a diferentes intervalos de tempo. Foram avaliados teor de umidade, germinação, comprimento da plântula e condutividade elétrica. Os resultados sugerem que sementes de A. alexandrae são recalcitrantes, com alta porcentagem de germinação (acima de 67%) quando não desidratadas (47% de umidade). Teores de água inferiores a 31,5% reduziram significativamente a taxa de germinação (<52,5%). Perda total da capacidade germinativa foi observada em sementes com 15,1% de umidade. Dentre os testes de vigor empregados, aquele que avalia a condutividade elétrica da água de embebição foi o mais sensível para a identificação da deterioração da semente em resposta à dessecação progressiva do lote em estudo.; The desiccation tolerance of Archontophoenix alexandrae (Wendl. & Drude) seeds was determined and the most sensitive vigor test for assessing seed deterioration of this species was identified. Mature fruits were harvested in the palm collection of the Instituto Agronomico in Campinas...

Protein expression upon desiccation and imbibition of Magnolia ovata A. St.-Hil seeds

José, Anderson Cleiton; Silva, Edvaldo Aparecido Amaral da; Davide, Antonio Claudio; Toorop, Peter
Fonte: Brazilian Archives of Biology and Technology Publicador: Brazilian Archives of Biology and Technology
Tipo: Artigo de Revista Científica Formato: 465-476
ENG
Relevância na Pesquisa
37.17%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); The effect of seed drying and imbibition was studied by differential protein expression using two dimensional gel electrophoresis. After drying to a range of water contents, seeds were germinated to assess the viability. Seeds of Magnolia ovata did not withstand the desiccation down to 0.10 g H2O · g-1 dw. The critical water content below which the desiccation sensitivity became apparent was around 0.18 g H2O · g-1 dw (-26.5 MPa). Total protein was extracted and separated by 2D electrophoresis from fresh seeds (0.28 g H2O · g-1 dw), mild dried seeds (0.25 g H2O · g-1 dw) and seeds at low water content (0.10 g H2O · g-1 dw) before and after imbibition for 10 days. The proteome profile revealed the presence of 588 spots on each silver stained gel, from which 21 showed differential expression, correlated with desiccation and germination, by increased or decreased expression. After MS/MS sequencing, three protein spots produced spectra that matched to a Magnolia salicifolia legumin precursor. Results suggested an involvement of this protein in the events taking place during the drying and subsequent imbibitions of the dried seeds.

Modeling 3-D desiccation soil crack networks using a mesh fragmentation technique

Sanchez, Marcelo; Manzoli, Osvaldo L.; Guimaraes, Leonardo J. N.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 27-39
ENG
Relevância na Pesquisa
37.07%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); The problem of desiccation cracks in soils has received increasing attention in the last few years, in both experimental investigations and modeling. Experimental research has been mainly focused on the behavior of slurries subjected to drying in plates of different shapes, sizes and thickness. The main objectives of these studies were to learn about the process of crack formation under controlled environmental conditions, and also to understand better the impact of different factors (e.g. soil type, boundary conditions, soil thickness) on the morphology of the crack network. As for the numerical modeling, different approaches have been proposed to describe the behavior of drying cracks in soils. One aspect that it is still difficult to simulate properly is the 3-D crack pattern typically observed in desiccated soils. In this work we present a numerical technique to model the behavior of drying soils. The proposed approach inserts high aspect ratio elements in-between standard elements of a finite element mesh. This mesh fragmentation technique can be easily adapted to standard finite element programs. We used this technique to analyze multiple case studies related to soil desiccation cracks developed under laboratory and field conditions. We focused our attention in some key factors that control the 3-D morphology of the drying cracks network in soils. We show that the proposed technique is able to simulate very satisfactorily the main patterns typically observed in cracked soils. (C) 2014 Elsevier Ltd. All rights reserved.

Biomphalaria tenagophila (Orbigny, 1835) (Mollusca): adaptation to desiccation and susceptibility to infection with Schistosoma mansoni Sambon, 1907

OHLWEILER,Fernanda Pires; KAWANO,Toshie
Fonte: Instituto de Medicina Tropical Publicador: Instituto de Medicina Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2002 EN
Relevância na Pesquisa
37.43%
Experiments were carried out to test the susceptibility of Biomphalaria tenagophila to the infection with strain SJ of Schistosoma mansoni in the F1, F2 and non-selected parental generation. The potential adaptation of B. tenagophila to desiccation, in healthy mollusks and those exposed to the larvae of S. mansoni of the F1, F2 and non-selected parental generations was also studied. The presence of mucus and soil, at the shell opening, protected the snails against desiccation, favoring survival. The healthy mollusks performed more attempts against desiccation than those exposed to the larvae of the parasite. The mortality rate, during desiccation, was higher among mollusks that remained buried and with the shell opening unobstructed. During the desiccation period the stage of development of the parasite was influenced by the weight loss and the survival of the snails. The longer the period of desiccation, the greater was the weight loss observed, abbreviating survival. The non-selected parental generation was more sensitive to desiccation than the F1 and F2 generations, both in healthy mollusks and in those exposed to S. mansoni larvae. Healthy mollusks were more resistant to desiccation than those exposed to the larvae of the S. mansoni. Desiccation did not interrupt the development of S. mansoni larvae in mollusks...

Effects of the desiccation on Biomphalaria tenagophila (Orbigny, 1835) (Mollusca) infected by Schistosoma mansoni Sambon, 1907

Ohlweiler,FP; Kawano,T
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2001 EN
Relevância na Pesquisa
37.3%
Specimens of Biomphalaria tenagophila exposed to miracidia of Schistosoma mansoni were submitted to different desiccation periods as follows: group I: 24 h after exposure, desiccated for 28 days; group II: after cercariae elimination, desiccated for 7 days; group III: 21 days after exposure, desiccated for 7 days; group IV: 14 days after exposure, desiccated for 14 days; group V: 7 days after exposure, desiccated for 21 days. From the obtained data it was verified that desiccation was not capable of interrupting the development of larvae of S. mansoni in mollusks. A delay in the development of S. mansoni larvae in groups I, III, IV and V was observed. A pause was verified in the development of S. mansoni larvae in groups II, III, IV and V. Some larvae, in groups I, III, IV and V, did not suffer as a result of desiccation and continued their development. Larvae in the cercariae stage were shown to be more sensitive to desiccation. It was possible to obtain clearing of mollusks infected by sporocysts II and cercariae using a period of 7 days of desiccation.

Changes in gene expression during drying and imbibition of desiccation sensitive Magnolia ovata (A. St.-Hil.) spreng. seeds

José,Anderson C.; Ligterink,Wilco; Davide,Antonio Claudio; Silva,Edvaldo A. Amaral da; Hilhorst,Henk W.M.
Fonte: Associação Brasileira de Tecnologia de Sementes Publicador: Associação Brasileira de Tecnologia de Sementes
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
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Seeds of Magnolia ovata were dried to different water contents to assess the viability and transcript abundance of genes related to seed development, cell cycle, cytoskeleton and desiccation tolerance.The expression of development, cell cycle and cytoskeleton relative genes (ABI3, CDC2-like and ACT2) alone could not explain the germination behaviour of M. ovata seeds in relation to drying damage. Irrespective of their initial water content, the seeds performed in the same way during the initial period of germination and the deleterious effects of desiccation only occurred in later stages. Expression of PKABA1, sHSP17.5 and 2-Cys-PRX did not show a relationship with desiccation. However, the expression patterns of PKABA1 and sHSP17.5 suggested the participation of these genes in protective mechanisms during the imbibition of M. ovata seeds.

Protein expression upon desiccation and imbibition of Magnolia ovata A. St.-Hil seeds

José,Anderson Cleiton; Silva,Edvaldo Aparecido Amaral da; Davide,Antonio Claudio; Toorop,Peter
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2011 EN
Relevância na Pesquisa
37.17%
The effect of seed drying and imbibition was studied by differential protein expression using two dimensional gel electrophoresis. After drying to a range of water contents, seeds were germinated to assess the viability. Seeds of Magnolia ovata did not withstand the desiccation down to 0.10 g H2O · g-1 dw. The critical water content below which the desiccation sensitivity became apparent was around 0.18 g H2O · g-1 dw (-26.5 MPa). Total protein was extracted and separated by 2D electrophoresis from fresh seeds (0.28 g H2O · g-1 dw), mild dried seeds (0.25 g H2O · g-1 dw) and seeds at low water content (0.10 g H2O · g-1 dw) before and after imbibition for 10 days. The proteome profile revealed the presence of 588 spots on each silver stained gel, from which 21 showed differential expression, correlated with desiccation and germination, by increased or decreased expression. After MS/MS sequencing, three protein spots produced spectra that matched to a Magnolia salicifolia legumin precursor. Results suggested an involvement of this protein in the events taking place during the drying and subsequent imbibitions of the dried seeds.

Desiccation resistance in Arcobacter butzleri

Otth,Laura; Wilson,Myra; Fernández,Heriberto
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2001 EN
Relevância na Pesquisa
37.24%
The desiccation resistance of A. butzleri was studied. Two, 3 and 4 of the strains did not resist desiccation for more than 2, 12 and 36 h, respectively. Two strains resisted desiccation for > 48 h. A. butzleri seems to be more resistant to desiccation than the classical enteropathogenic Campylobacter species.

Loss of desiccation tolerance in Copaifera langsdorffii Desf. seeds during germination

Pereira,WVS.; Faria,JMR.; Tonetti,OAO; Silva,EAA.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/05/2014 EN
Relevância na Pesquisa
37.24%
This study evaluated the loss of desiccation tolerance in C. langsdorffii seeds during the germination process. Seeds were imbibed for 24, 48, 72, 96, 120 and 144 hours and dried to the initial moisture content, kept in this state for 3 days after which they were submitted to pre-humidification and rehydration. Ultraestructural evaluations were done aiming to observe the cell damage caused by the dry process. Desiccation tolerance was evaluated in terms of the percentage of normal seedlings. Seeds not submitted to the drying process presented 61% of normal seedlings, and after 24 hours of imbibition, followed by drying, the seeds presented the same percentage of survival. However, after 48 hours of imbibition, seeds started to lose the desiccation tolerance. There was twenty six percent of normal seedlings formed from seeds imbibed for 96 hours and later dried and rehydrated. Only 5% of seeds imbibed for 144 hours, dried and rehydrated formed normal seedlings. At 144 hours of imbibition followed the dry process, there was damage into the cell structure, indicating that the seeds were unable to keep the cell structure during the drying process. Copaifera langsdorffii seeds loses the desiccation tolerance at the start of Phase 2 of imbibition.

Fluorescence Studies of Photosystem II Fluorescence Quenching During Desiccation

Schaven, Kristin S.
Fonte: Brock University Publicador: Brock University
Tipo: Electronic Thesis or Dissertation
ENG
Relevância na Pesquisa
37.3%
Poikilohydric organisms have developed mechanisms to protect their photosynthetic machinery during times of desiccation. In hydrated conditions nonphotochemical quenching (NPQ) mechanisms are able to safely dissipate excess excitation energy as heat, but mechanisms of NPQ associated with desiccation tolerance are still largely unclear. In the lichen Parmelia sulcata, photosystem protection has been associated with an energy quenching energetically coupled to PSII and characterized by a fast-fluorescence decay lifetime, and long-wavelength emission. The present study compares the relative ability of green algae and lichens to recover photosynthetic activity after periods of desiccation using steady state fluorescence emission spectroscopy, and picosecond time-resolved fluorescence decay measurements. It was determined that desiccation induced quenching involves an antenna quenching mechanism with similar characteristics appearing in both P. sulcata and green algae. Algae isolated from lichens suggest symbiosis in the lichen appears to enhance this naturally occurring phenomenon and provide greater protection during desiccation.

Loss of desiccation tolerance in Copaifera langsdorffii Desf. seeds during germination

Pereira, Wilson Vicente Souza; Faria, José Marcio Rocha; Tonetti, Olivia Alvina Oliveira; Silva, Edvaldo Aparecido Amaral da
Fonte: Int Inst Ecology Publicador: Int Inst Ecology
Tipo: Artigo de Revista Científica Formato: 501-508
ENG
Relevância na Pesquisa
37.24%
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); This study evaluated the loss of desiccation tolerance in C. langsdorffii seeds during the germination process. Seeds were imbibed for 24, 48, 72, 96, 120 and 144 hours and dried to the initial moisture content, kept in this state for 3 days after which they were submitted to pre-humidification and rehydration. Ultraestructural evaluations were done aiming to observe the cell damage caused by the dry process. Desiccation tolerance was evaluated in terms of the percentage of normal seedlings. Seeds not submitted to the drying process presented 61% of normal seedlings, and after 24 hours of imbibition, followed by drying, the seeds presented the same percentage of survival. However, after 48 hours of imbibition, seeds started to lose the desiccation tolerance. There was twenty six percent of normal seedlings formed from seeds imbibed for 96 hours and later dried and rehydrated. Only 5% of seeds imbibed for 144 hours, dried and rehydrated formed normal seedlings. At 144 hours of imbibition followed the dry process, there was damage into the cell structure, indicating that the seeds were unable to keep the cell structure during the drying process. Copaifera langsdorffii seeds loses the desiccation tolerance at the start of Phase 2 of imbibition.; Este estudo avaliou a perda da tolerância à dessecação em sementes de C. langsdorffii durante o processo germinativo. Sementes foram embebidas por 24...

Southernpea response to Glyphosate desiccation.

COLE, A.W.; CERDEIRA, A. L.
Fonte: HortScience, v.17, n.2, p.244-246, Apr. 1982. Publicador: HortScience, v.17, n.2, p.244-246, Apr. 1982.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
37.17%
Seed weight, germination, seedling emergence, and yields were examined following desiccation of southernpea [Vigna unguiculata (L.) Walp cv. Mississipi Purple] plants with glyphosate [N-(phosphonomethyl)glycine]. Dry seed weight was not reduced by the desiccation process; however, seed quality of those treated at immature stages was reduced. Germination, seedling emergence, and yield from seed desiccated at immature stages were significantly less than from seeds desiccated at more mature stages of development. No differences were apparent between desiccation at mature stages and the control.; 1982

Desiccation tolerance in seeds of Annona emarginata (Schldtl.) H. Rainer and action of plant growth regulators on germination

Corsato,Jaqueline Malagutti; Ferreira,Gisela; Barbedo,Claudio Jose
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
Relevância na Pesquisa
37.37%
Annona emarginata (Schldtl.) H. Rainer ("araticum-de-terra-fria") is used as a rootstock for several species of Annonaceae. It is suggested that these seeds should be sown immediately after extraction and, therefore, they could be intolerant to desiccation. There are several mechanisms involved with desiccation tolerance. Soluble sugars, for example, can accumulate and act as osmoprotectants for the membrane system during desiccation. The aim of this study is to assess desiccation tolerance in A. emarginata seeds. In addition, we examined the soluble sugars involved in desiccation tolerance. Finally, we determined the effect of gibberellic acid (GA4+7) and N-(phenylmethyl)-aminopurine in promoting the germination of seeds with different water contents. The experiment consisted of a randomized 4x5 factorial design (desiccation levels x concentration of growth regulators). After drying, seeds containing 31 (control), 19, 12 and 5% water were incubated in different concentrations of GA4+7 N-(phenylmethyl)-aminopurine (0, 250, 500, 750 and 1000 mg L-1) for 60 hours. The experiment was conducted in a germination chamber with alternating temperature and photoperiod of 20ºC for 18 hours of darkness and 30ºC for 6 hours of light. We analyzed electrical conductivity...

Influence of substrate humidity on desiccation resistance capacity in Subulina octona (Mollusca, Subulinidae)

Dias,Roberto Júnio Pedroso; Bessa,Elisabeth Cristina de Almeida; D'Ávila,Sthefane
Fonte: Instituto de Tecnologia do Paraná - Tecpar Publicador: Instituto de Tecnologia do Paraná - Tecpar
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
Relevância na Pesquisa
37.07%
The aim of this study was to verify the influence of substrate humidity on desiccation resistance of Subulina octona, continuously exposed, for 48 h, to the temperature of 35 °C. Forty individuals conditioned in 2 plastic boxes, one box containing black earth humidified with 40 ml water and the other one containing dry black earth were used. The retraction of cephalopodal mass inside the shell and the number of dead individuals was evaluated. Snails from dry and humid substrate boxes showed cephalopodal mass retraction of 9.9 cm±2.88 and 2.78 cm±3.17, respectively, after 12 h of exposure; 8.55 cm±1.3 and 6.33 cm±2.91, after 24 h; 11.07 cm±4.19 and 7.27 cm±2.7, after 36 h, 9.12 cm±2.15 and 6.47 cm±2.11, after 48 h. Every individual of dry substrate box died whereas every individual of humid substrate box survived. These results showed that substrate humidity was an influent factor regarding desiccation resistance in S. octona.

Biomphalaria tenagophila (Orbigny, 1835) (Mollusca): adaptação à dessecação e suscetibilidade à infecção pelo Schistosoma mansoni Sambon, 1907; Biomphalaria tenagophila (Orbigny, 1835) (Mollusca): adaptation to desiccation and susceptibility to infection with Schistosoma mansoni Sambon, 1907

OHLWEILER, Fernanda Pires; KAWANO, Toshie
Fonte: Universidade de São Paulo. Instituto de Medicina Tropical de São Paulo Publicador: Universidade de São Paulo. Instituto de Medicina Tropical de São Paulo
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/07/2002 ENG
Relevância na Pesquisa
37.43%
Foram realizados experimentos para testar a suscetibilidade de B. tenagophila à infecção pela cepa SJ do S. mansoni, das gerações F1, F2 e parental não selecionada. O potencial de adaptação de B. tenagophila à dessecação, em moluscos sadios e expostos às larvas do S. mansoni também foi estudado. A presença de muco e terra na abertura da concha protege os moluscos da dessecação, favorecendo a sobrevivência. Os moluscos sadios tiveram mais tentativas de proteção contra a dessecação do que os moluscos expostos às larvas do parasita. A mortalidade, durante a dessecação, foi maior entre os moluscos que permaneceram enterrados e apresentaram a abertura da concha desobstruída. O estágio de desenvolvimento das larvas do parasita influenciou na perda de peso e na sobrevivência dos moluscos. Quanto maior o período de dessecação, maior a perda de peso, sendo a sobrevida abreviada. A geração parental não selecionada mostrou-se mais sensível à dessecação que as gerações F1 e F2, tanto nos moluscos sadios como naqueles expostos às larvas do parasita. Os moluscos sadios foram mais resistentes à dessecação que os moluscos expostos às larvas do parasita. A dessecação não interrompeu o desenvolvimento de larvas do S. mansoni nos moluscos...

Efeito de diferentes níveis de dessecamento na germinação de sementes de Euterpe edulis Martius - Arecaceae; Effect of different level of desiccation in the seed germination of Euterpe edulis Martius - Arecaceae

Reis, Ademir; Universidade Federal de Santa Catarina, Florianópolis; Paulilo, Maria Terezinha Silveira; Universidade Federal de Santa Catarina, Florianópolis; Nakazono, Erika Matsuno; Universidade Federal de Santa Catarina, Florianópolis; Venturi, Silv
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; Formato: application/pdf
Publicado em 01/01/1999 POR
Relevância na Pesquisa
37.07%
O objetivo deste estudo foi verificar o efeito de diferentes níveis de dessecamento sobre a germinação de sementes de Euterpe edulis Martius. As sementes com teor inicial de umidade de 50% foram secas através de dois métodos: I) Sementes colocadas em estufa de ar forçado a 28°C por 48h.; II) Sementes colocadas para dessecar em laboratório, a temperatura e umidade relativa ambientes por períodos de 2, 4, 8, 16, 32 e 64 dias. As principais conclusões foram: Sementes secas por 48 horas em estufa de ar forçado alcançaram teor de umidade de cerca de 32%, não tendo esta diminuição de umidade afetado a percentagem de germinação. A percentagem de germinação começou a decrescer em sementes com menos de 28% de umidade, condição que foi alcançada após 8 dias de dessecamento da semente em condições naturais de temperatura e umidade. Sementes com cerca de 20% ou menos de umidade reduziram drasticamente sua capacidade germinativa, tendo o teste de tetrazólio aplicado a estas sementes mostrado a morte do embrião. A sensibilidade de sementes de E. edulis ao dessecamento, mostrada neste estudo, indica comportamento de sementes recalcitrantes.; The aim of this study was to verify the germination of Euterpe edulis seeds submitted to different leveIs of desiccation. Seeds with inicial moisture content of 50% were dried by two methods: I - for O to 48 hours in forced air oven at 28°C; II - for 2 to 64 days at room temperature and relative humidity. The main conclusions were: seeds dried for 48 hours in forced dried oven reached moisture content of 32% and this lower moisture content did not affect the germination percentage. The percentage of germination started to decrease in seeds with less than 28% of moisture content...

Effects of desiccation on Euterpe edulis Martius seeds

Panza,Víctor; Láinez,Verónica; Maldonado,Sara; Maroder,Horacio L
Fonte: Biocell Publicador: Biocell
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 EN
Relevância na Pesquisa
37.17%
Information on desiccation sensitivity of Euterpe edulis seeds under two drying rates is presented. The sensitivity was studied during the course of germination and normal germination. The water content was evaluated for both seeds and embryos. Results showed the following: (a) For both drying treatments and for both germination and normal germination, desiccation sensitivity values were higher for measurements based on the water content of the embryo than for those of the seed. (b) For both drying treatments, desiccation sensitivity were higher for normal germination than for germination based on both the embryo and seed water contents. (c) Under the slow drying treatment and for measurements based on the seed water content, critical water content was visible for normal germination but not for germination; (d) Critical water contents for germination and normal germination were more clearly established in the fast drying treatment than they were in the slow drying method based on both the embryo and seed water contents. Critical water contents were not associated with changes in electrolyte leakage, which suggests that conductivity is not a good indicator of physiological seed quality. From the beginning of both drying treatments, changes in nuclei and vacuoles were observed...

Desiccation of soil by vegetation and potential interaction with buildings: a field study

Blight,GE
Fonte: Journal of the South African Institution of Civil Engineering Publicador: Journal of the South African Institution of Civil Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2009 EN
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Desiccation of clay soil caused by vegetation - grass, bushes and trees - and its effects on the stability of slopes, buildings, roads and other structures has long been a topic of interest and concern to the geotechnical engineer. Several international symposia on the topic have been held during the past 60 years, and the literature on the subject is voluminous. A review of past studies of soil desiccation and its effects showed that, with few exceptions, investigations had been of a short-term nature and had not adequately considered the variable annual effects of atmospheric and hydrological causes of soil desiccation and rehydration. As a contribution to providing this longer-term information, it was decided to embark on an extended study of the effects of evapotranspiration by vegetation and atmospheric climate on the seasonal and year-to-year variation of soil water content. The study is now complete and this paper presents an overview of the investigation from 2000 to 2006, including the influence of annual weather variations on the desiccating effects of lines of trees and bushes, the potential effects of desiccation caused by single trees on adjacent buildings, and the portrayal of these effects by means of soil water content and storage profiles...