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Comportamento da dormência de sementes de Brachiaria dictyoneura cv. Llanero submetidas às ações do calor e do ácido sulfúrico.; Effects of heating and sulfuric acid on seed dormancy of Brachiaria dictyoneura cv. Llanero.

Almeida, Clodoaldo Rocha de
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 31/10/2002 PT
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A literatura específica destaca a dormência das sementes como fator dificultador do estabelecimento das pastagens de gramíneas forrageiras tropicais. A imersão das sementes em ácido sulfúrico (H2SO4), apesar de funcionalmente admitida como eficiente para promover a redução da dormência em sementes de braquiária, apresenta inconveniências relacionadas à segurança do trabalhador envolvido na aplicação e, adicionalmente, à preservação do meio ambiente com o descarte dos resíduos provenientes da operação. Dessa maneira, objetivando identificar alternativas para a superação da dormência, o presente estudo realizou comparações entre os efeitos fisiológicos de tratamentos térmicos (55, 65, 75 e 85 o C/5, 10 e 15 h) e químico (imersão em H2SO4/15 minutos) em sementes de Brachiaria dictyoneura cv. Llanero (Brachiaria humidicola cv. Llanero, segundo Renvoize et al., 1996). Para tanto, as sementes foram qualitativamente avaliadas (teor de água, germinação, tetrazólio, primeira contagem de germinação, emergência de plântulas, comprimento da parte aérea das plântulas e índice de velocidade de emergência) em duas épocas experimentais (início e final do armazenamento de 6 meses). Os usos do calor e do ácido sulfúrico constituem-se em alternativas para a redução da dormência das sementes e conseqüente favorecimento do desempenho fisiológico. Contudo...

O papel dos lipídios na reorganização metabólica associada à dormência sazonal no lagarto teiú Tupinambis merianae (Sauria, Teidae); The role of lipids in the metabolic reorganization associated to seasonal dormancy in tegu lizards, Tupinambis merianae (Sauria, Teiidae)

Haddad, Laura Saade
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 03/12/2007 PT
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O jejum prolongado associado `a dormência sazonal é um fenômeno característico de diversos grupos de vertebrados, e os lipídios tem se mostrado bastante importantes na manutenção destes animais. No presente estudo pretendeu-se caracterizar a reorganização metabólica no jejum de 3-4 meses associado à dormência e depressão metabólica acentuada em lagartos teiú no primeiro ciclo anual de atividades, elucidando (1) qual o papel do metabolismo lipídico e de outros substratos energéticos na regulação da massa corpórea e da taxa metabólica dos teiús jovens ao longo do primeiro ciclo anual (2) qual é o comportamento de enzimas do metabolismo energético de diferentes substratos ao longo do ciclo sazonal, relacionadas à manutenção dos teiús durante o jejum hipometabólico e no retorno a atividade. (3) qual é perfil dos ácidos graxos do plasma e diferentes tecidos ao longo do ciclo sazonal e (4) testar se as predições da teoria da membrana como marca-passo do metabolismo se aplicam a um modelo intra-específico e sazonal, de forma a explicar a regulação da acentuada depressão metabólica nos lagartos teiú Para tal, foram determinadas as atividades de enzimas das vias do metabolismo energético de carboidratos (PECK)...

Reorganização estrutural e metabólica do intestino associada ao jejum e dormência sazonal em lagartos teiú Tupinambis merianae; Structural and metabolic reorganization of the gut during the fasting and seasonal dormancy in tegu lizards Tupinambis merianae

Nascimento, Lucas Francisco Ribeiro do
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 30/07/2009 PT
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A plasticidade fenotípica do intestino está presente em diferentes grupos de vertebrados e permite ajustes de caráter antecipatório ou de curto prazo na capacidade funcional do intestino frente a flutuações previsíveis e não previsíveis na disponibilidade de alimento no ambiente. No presente trabalho, avaliamos as alterações sazonais na morfologia e na capacidade de oxidação de substratos energéticos no intestino médio de lagartos teiú Tupinambis merianae. A resposta ao jejum associado à depressão metabólica na dormência de inverno foi contrastada com as alterações após 20 dias de jejum na fase ativa. Grupos de animais jovens foram mortos em diferentes fases do primeiro ciclo anual e o intestino médio foi removido e pesado. Amostras do terço proximal do órgão foram transferidas para frascos contendo formaldeído tamponado e o restante do tecido foi picotado e amostras aleatórias foram congeladas em N2 líquido e transferidas para freezer -80 oC. Variáveis morfológicas foram analisadas em cortes histológicos de 5 μm de espessura utilizando-se o método estereológico. O teor de água e o de proteína solúvel e total foi medido nas amostras por meio de ensaios padrão; as atividades máximas de enzimas foram medidas por espectrofotometria em condições saturantes de substrato e cofatores. No outono...

Dormencia em sementes de arroz vermelho; Dormancy in seeds of red rice

Delatorre, Carla Andrea
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
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O arroz vermelho é considerado a principal planta daninha na maioria das lavouras de arroz, pois, além dos prejuízos causados pela competição, sua similaridade com o arroz cultivado dificulta seu controle. A dormência e a viabilidade de suas sementes no solo permitem a continuidade dos biotipos na lavoura e facilitam a disseminação para áreas próximas. A duração e a intensidade da dormência variam com o biotipo e com as condições ambientais vigentes durante o desenvolvimento da semente. A maior parte dos ecotipos apresenta dois tipos de dormência, uma devido às estruturas envoltórias e outra devido ao embrião. O período necessário para a superação da dormência é dependente das condições (temperatura e umidade) a que a semente é exposta após a maturação. Várias substâncias têm sido eficientes na quebra da dormência, em especial, ácidos e citocininas. Outros reguladores tiveram apenas efeito parcial. Ressalta- se que todas as substâncias testadas não atuaram sobre as estruturas envoltórias. O mecanismo pelo qual ocorre a manutenção/ alívio da dormência permanece desconhecido.; Red rice is considered the major weed in rice areas. The similarity between red rice and cultivated rice difficults the red rice control. Seed dormancy and viability in the soil allow the maintanence of the biotype in the area and facilite the dissemination in surrounded areas. Dormancy duration and intensity depend on biotype and environmental conditions during seed development. In general...

On the germination and dormancy of dispersal units of Brachiaria decumbens STAPF

deLima, V. L.; Cardoso, VJM
Fonte: Inst Tecnologia Parana Publicador: Inst Tecnologia Parana
Tipo: Artigo de Revista Científica Formato: 595-606
ENG
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The effect of light and temperature on germination of Brachiaria decumbens as well as the action of some dormancy breaking chemicals were tested. Two seed batches stored different times were used. The results show that seeds failed to respond to alternating temperature regimes and different light qualities. Seeds were indifferent to white light at 25 degrees C. KNO3, ethanol and H2SO4 failed to break seed dormancy, whereas KCN and H2O2 partially reduced dormancy of two month stored seeds. The results suggest a metabolic character of dormancy in 'new' (freshly collected) seeds and confirm the occurence of two types of dormancy in B. decumbens seeds.

On the germination and dormancy of dispersal units of Brachiaria decumbens staff

De Lima, Vandré Lopes; Cardoso, Victor José Mendes
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 595-606
ENG
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The effect of light and temperature on germination of Brachiaria decumbens as well as the action of some dormancy breaking chemicals were tested. Two seed batches stored different times were used. The results show that seeds failed to respond to alternating temperature regimes and different light qualities. Seeds were indifferent to white light at 25°C. KNO3, ethanol and H2SO4 failed to break seed dormancy, whereas KCN and H2O2 partially reduced dormancy of two month stored seeds. The results suggest a metabolic character of dormancy in new (freshly collected) seeds and confirm the occurence of two types of dormancy in B. decumbens seeds.

An immunoproteomic approach for characterization of dormancy within Staphylococcus epidermidis biofilms

Carvalhais, V.; Cerveira, Frederico; Vilanova, Manuel; Cerca, Nuno; Vitorino, Rui
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /06/2015 ENG
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Virulence of Staphylococcus epidermidis is mainly attributed to surface colonization and biofilm formation in indwelling medical devices. Physiological heterogeneity of biofilms may influence host immune response and sensitivity to antibiotics. Dormant cells, among others, contribute to biofilm heterogeneity. The aim of this study was to identify immunogenic proteins of S. epidermidis biofilms associated with dormancy mechanism, by using two-dimensional electrophoresis (2-DE) immunoblotting and mass spectrometry (MS). A total of 19 bacterial proteins, recognized by human serum samples, were identified. These proteins were mainly involved in small molecule metabolic biological processes. Catalytic activity and ion binding were the most representative molecular functions. CodY and GpmA proteins were more reactive to sera when biofilm dormancy was induced, while FtnA and ClpP were more reactive when dormancy was prevented. This is the first work that identifies differences in immunoreactive proteins within bacterial biofilms with induced or prevented dormancy. Considering the importance of dormancy within biofilms, further evaluation of these proteins can provide insights into the mechanisms related to dormancy and help to improve current understanding on how dormancy affects the host immune response.

Proteomic profile of dormancy within Staphylococcus epidermidis biofilms using iTRAQ and label-free strategies

Carvalhais, V.; Cerca, Nuno; Vilanova, Manuel; Vitorino, Rui
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em /03/2015 ENG
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Staphylococcus epidermidis is an important nosocomial bacterium among carriers of indwelling medical devices, since it has a strong ability to form biofilms. The presence of dormant bacteria within a biofilm is one of the factors that contribute to biofilm antibiotic tolerance and immune evasion. Here, we provide a detailed characterization of the quantitative proteomic profile of S. epidermidis biofilms with different proportions of dormant bacteria. A total of 427 and 409 proteins were identified by label-free and label-based quantitative methodologies, respectively. From these, 29 proteins were found to be differentially expressed between S. epidermidis biofilms with prevented and induced dormancy. Proteins overexpressed in S. epidermidis with prevented dormancy were associated with ribosome synthesis pathway, which reflects the metabolic state of dormant bacteria. In the opposite, underexpressed proteins were related to catalytic activity and ion binding, with involvement in purine, arginine, and proline metabolism. Additionally, GTPase activity seems to be enhanced in S. epidermidis biofilm with induced dormancy. The role of magnesium in dormancy modulation was further investigated with bioinformatics tool based in predicted interactions. The main molecular function of proteins...

Heart rate and body weight alterations in juvenile specimens of the tropical land snail Megalobulimus sanctipauli during dormancy

Rizzatti,A.C.S.; Romero,S.M.B.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2001 EN
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The time course of heart rate and body weight alterations during the natural period of dormancy were determined in active feeding and dormant juvenile specimens of Megalobulimus sanctipauli. In both groups, heart rate markedly decreased during the first 40 days of dormancy, tending to stabilize thereafter. This time period coincided with the decrease in environmental temperature during autumn-winter. At the end of the dormancy period, surviving active feeding and dormant snails showed a significant decrease in heart rate which, however, was significantly greater in the latter group. Total body weight decreased concomitantly with heart rate in dormant snails but remained constant in active feeding snails. Body hydration induced significant increases in weight and heart rate in surviving dormant snails. Feeding following hydration promoted a new significant increase in heart rate but not in weight. These results indicate that the decrease in heart rate observed in juvenile specimens of M. sanctipauli during dormancy may be due to at least three factors: 1) decrease in environmental temperature during autumn-winter, 2) starvation which leads to the depletion of endogenous fuel reserves and to a probable decrease in hemolymph nutrient levels...

Action of gibberellic acid (GA3) on dormancy and activity of alpha-amylase in rice seeds

Vieira,Antônio Rodrigues; Vieira,Maria das Graças Guimarães Carvalho; Fraga,Antônio C.; Oliveira,João Almir; Santos,Custódio D. dos
Fonte: Associação Brasileira de Tecnologia de Sementes Publicador: Associação Brasileira de Tecnologia de Sementes
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2002 EN
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To evaluate the effectiveness of gibberellic acid (GA3) in breaking rice seed dormancy and the use of alpha-amylase enzyme activity as an indicator of the dormancy level, seed from the intensively dormant irrigated cultivar Urucuia were used. The seeds were submitted to a pre-drying process in a forced air circulation chamber under 40ºC during 7 days and submersed in 30 mL of GA3 solution under 0, 10, 30 and 60 mg/L H2O concentrations, during 2, 24 and 36 hours. After the treatments, the alpha-amylase activity was determined by using the polyacrilamide electrophoresis and spectrophotometry. At the same time, the germination test was made. The results indicated a gain in germination and in alpha-amylase activity in higher concentrations and soaking time of seeds in GA3. These observations support the conclusion that soaking seed in 60 mg GA3/L during 36 hours can be used as a quick and efficient treatment in breaking rice seed dormancy and is equivalent to the forced air circulation chamber at 40ºC during 7 days. The alpha-amylase enzyme activity proved to be as an efficient marker of the seeds dormancy level.

Sowing seeds for the future: the need for establishing protocols for the study of seed dormancy

Silveira,Fernando Augusto Oliveira
Fonte: Sociedade Botânica do Brasil Publicador: Sociedade Botânica do Brasil
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2013 EN
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Seed dormancy is a widely misunderstood plant trait. In several research areas, a lack of germination is wrongly assumed to result from seed dormancy. In an attempt to standardize seed dormancy research and improve communication among seed scientists, a straightforward protocol to address the occurrence and causes of seed dormancy is provided. Standardizing communication is not just a theoretical exercise but also has practical implications in agriculture and conservation. Standardization will make studies comparable and hence we will have a deeper understanding of the physiology, ecology and evolution of seed dormancy. A better understanding of the various aspects of seed dormancy will lead to greater appreciation of the biogeographical and phylogenetic distribution of seed dormancy among our flora.

Physiological, physical, and morpho-anatomical changes in Libidibia ferrea ((Mart. ex Tul.) L.P. Queiroz) seeds after overcoming dormancy

Matos,Antônio César Batista; Ataíde,Glauciana da Mata; Borges,Eduardo Euclydes de Lima e
Fonte: ABRATES - Associação Brasileira de Tecnologia de Sementes Publicador: ABRATES - Associação Brasileira de Tecnologia de Sementes
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2015 EN
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Seed dormancy is a phenomenon that affects the distribution of plant species in time. However, it may slow germination and consequently hinder seedling production in nurseries. Many seeds of forest species of the Fabaceae family, such as Libidibia ferrea (Brazilian ironwood), have physical dormancy caused by impermeability of the seed coat to water. Therefore, the aim of this study was to evaluate the physiological, physical, and morpho-anatomical characteristics of L. ferrea seeds before and after application of different treatments for overcoming dormancy. We evaluated the imbibition curves, germination percentage, germination speed index (GSI), the force required to puncture the micropylar region, and morpho-anatomical changes through images obtained from a scanning electron microscope (SEM) before and after application of treatments for overcoming dormancy. L. ferrea seeds immersed in sulfuric acid show a triphasic pattern of imbibition. The required force to puncture the micropylar region of L. ferrea seeds is less for both the treatment with boiling water and for treatments with sulfuric acid. In addition, the required force to puncture the micropylar region decreases during imbibition of the seeds after application of sulfuric acid. The time of application of sulfuric acid influences the thickness of the material removed from the macrosclereid layer of the seed coat.

Indu????o de muta????o em sementes de arroz (Oryza sativa L.) e sele????o de poss??veis mutantes M2 para a dorm??ncia e toler??ncia ao frio na germina????o; Mutation induction in rice seeds (Oryza sativa L.) and selection of putative M2 mutants for dormancy and germination under low temperature

MANSOUR, Daniela Hernandes
Fonte: Universidade Federal de Pelotas; Agronomia; Programa de P??s-gradua????o em Ci??ncia e Tecnologia de Sementes; UFPel; BR Publicador: Universidade Federal de Pelotas; Agronomia; Programa de P??s-gradua????o em Ci??ncia e Tecnologia de Sementes; UFPel; BR
Tipo: Dissertação Formato: application/pdf
POR
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Cultivated in more than 150 million hectares, rice (Oryza sativa L.) is one of the most important crops around the world. In 2005 approximately 600 millions tons were harvested. Moreover, the rice grain is the basic food for at least four billion people worldwide. Rice breeding programs are looking for the development of new varieties with higher productivity, nutritionally traits and environment stresses tolerance. Initially using the existing variability to create new recombination, through artificial hybridizations, and, later, inducing mutations. The generation of a mutant population looking for selects putative mutants for dormancy and tolerance to low temperature during germination, may be contribute to know mechanisms involved in these traits, moreover in the future, it may be possible to develop new and better genotypes. The goal of this work was to generate a mutant population of rice from the BRS 7 Taim cultivar and to identify putative mutants for dormancy and germination under low temperature. Ten thousand seeds of the BRS 7 Taim cultivar were submitted to 250 Gy. The M1 seeds were cultivated in field to produce M2 seeds. Thirty M2 seed populations were harvested and evaluated. The mutation induction allowed the generation of a mutant bank with differentiated performance for dormancy and tolerance to low temperature in the germination. The M2 24 seed population seems to be the better one to study the dormancy trait. The M2 mutant populations showed different performance in the germination test under 13??C...

Drought and high temperature increases preharvest sprouting tolerance in a genotype without grain dormancy

Biddulph, T.; Mares, D.; Plummer, J.; Setter, T.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2005 EN
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Preharvest sprouting is common in cereals, which lack grain dormancy when maturing grain is exposed to rainfall or high moisture conditions. Environmental conditions such as drought and high temperature during grain filling have a large effect on the expression of sprouting tolerance. A dormant (DM 2001) and non-dormant (Cunderdin) hard white spring wheat were exposed to drought or irrigated conditions and either low or high temperature during grain filling. Dormancy and embryo sensitivity to ABA were analysed throughout grain filling. The conclusions from this investigation were as follows; firstly DM 2001 was more dormant than Cunderdin, with a four-fold lower germination index (GI) at maturity. Secondly during grain ripening drought increased dormancy and overrides any increase in dormancy with low temperature. Finally embryo sensitivity can be induced in a non-dormant genotype to the extent where the non-dormant genotype in a hot dry environment can have the same phenotype as a dormant genotype grown in a cool wet environment. In summary drought during grain filling increases dormancy suggesting breeders need to avoid drought when screening for sprouting tolerance in order to maximise the chances of identifying genetic differences in grain dormancy and avoid any maturity by drought interactions.; Special Issue: Proceedings of the 10th International Symposium on Pre-Harvest Sprouting in Cereals...

Effect of grain colour gene (R) on grain dormancy and sensitivity of the embryo to abscisic acid (ABA) in wheat

Himi, E.; Mares, D.; Yanagisawa, A.; Noda, K.
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2002 EN
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The level of grain dormancy and sensitivity to ABA of the embryo, a key factor in grain dormancy, were examined in developing grains of a white-grained wheat line, Novosibirskaya 67 (NS-67), and its red-grained near-isogenic lines (ANK-1A to -1D); a red-grained line, AUS 1490, and its white-grained mutant line (EMS-AUS). ANK lines showed higher levels of grain dormancy than NS-67 at harvest maturity. AUS 1490 grain also showed higher dormancy than EMS-AUS grain. These results suggest that the R gene for grain colour can enhance grain dormancy. However, the dormancy effect conferred by the R gene was not large, suggesting that it plays a minor role in the development of grain dormancy. Water extracts of AUS 1490 and EMS-AUS bran contained germination inhibitors equivalent to 1–10 µM ABA, although there was no difference in the amount of inhibitors between AUS 1490 and EMS-AUS. Thus, the grain colour gene of AUS 1490 did not appear to enhance the level of grain dormancy by accumulating germination inhibitors in its bran. Sensitivity to ABA of embryos was higher in grains collected around harvest-maturity for ANK lines and AUS 1490, compared with NS-67 and EMS-AUS. The R gene might enhance grain dormancy by increasing the sensitivity of embryos to ABA.; Eiko Himi...

Role of the seed coat in the dormancy of wheat (Triticum aestivum) grains.

Rathjen, Judith Rebecca
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2006
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Pre-harvest sprouting (PHS) is an important economic problem which affects a significant proportion of the Australian wheat crop through quality downgrading. Grain dormancy is the most effective means of overcoming germination in the wheat spikelet at harvest maturity. It has been a consistent observation over a long period of time that dormant red-grained wheat genotypes are almost more dormant than dormant white-grained genotypes. In white-grained wheat, there are two factors which contribute to dormancy, embryo sensitivity to abscisic acid (ABA) and an interacting and unknown seed coat factor. The proposed dormancy model is that complete dormancy can only be achieved with the coordinate expression of these two factors. This primary objective of this project was to determine the role of this putative seed coat factor in grain dormancy of white-grained wheat."--Abstract.; Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006; Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library.

Seed storage-mediated dormancy alleviation in Fabaceae from campo rupestre

Nativel,Naïla; Buisson,Elise; Silveira,Fernando Augusto Oliveira
Fonte: Sociedade Botânica do Brasil Publicador: Sociedade Botânica do Brasil
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2015 EN
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ABSTRACTWe studied the effects of seed storage on germination and dormancy alleviation in three species of Fabaceae endemic to campo rupestrein southeastern Brazil. Fresh seeds of Collaea cipoensis, Mimosa maguirei and Mimosa foliolosawere set to germinate and germination of seeds after four, five and 13 years of storage was tested. Seed viability was maintained for all species after the full storage period. Seed storage significantly increased germination percentage and decreased germination time for C. cipoensisand M. foliolosa, suggesting the alleviation of physical dormancy with storage. However, we did not find evidence of dormancy alleviation in M. maguirei since stored seeds showed a decrease in germination in comparison to that of fresh seeds. Our data indicate species-specific storage-mediated dormancy alleviation, which will have important implications for restoration of campo rupestre.

Germination and Dormancy in Seeds of Sorghum halepense and Sorghum arundinaceum

Krenchinski,F.H.; Albrecht,A.J.P.; Albrecht,L.P.; Villetti,H.L.; Orso,G.; Barroso,A.A.M.; Victoria Filho,R.
Fonte: Sociedade Brasileira da Ciência das Plantas Daninhas Publicador: Sociedade Brasileira da Ciência das Plantas Daninhas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2015 EN
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Light, temperature and dormancy are factors that influence the germination of seeds and are strictly linked to the emergence of weeds. The objective of this work was to assess the germination of Sorghum arundinaceum and Sorghum halepense subjected to different conditions of temperature and luminosity, as well as assessing seed dormancy breaking mechanisms. For this, two experiments were conducted, both arranged in a completely randomized design. Experiment 1 was installed in a 2 x 5 double factorial design. The first factor was the absence or presence of light for 12 hours, and the other was composed of five constant temperatures: 15, 20, 30, 40 and 45 oC. In experiment 2, the efficiency of nine treatments used for breaking dormancy of seeds was assessed. The variables analyzed for both experiments were germination percentage and germination speed index (GSI). For the statistical analysis were performed an analysis of variance (ANOVA) and all the necessary consequences, as well as regression, when relevant. In experiment 1 for both species greater germination occurred in the presence of light. For S. arundinaceum the temperatures at which there was the highest percentage of germination were 33.13 and 31.24 oC for presence and absence of light respectively. As for S. halepense these temperatures were 31.98 and 29.75 oC for presence and absence of light respectively. As for the treatments for breaking dormancy...

Dormancy studies on Euphorbia dracunculoides and Astragalus spp.: major weeds of arid areas

Ikram,R.M.; Tanveer,A.; Ata,Z.; Saqib,M.
Fonte: Sociedade Brasileira da Ciência das Plantas Daninhas Publicador: Sociedade Brasileira da Ciência das Plantas Daninhas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 EN
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The aim of this study was to examine the dormancy behavior of Euphorbia dracunculoides and Astragalus spp., weeds of arid chickpea. The dormancy breaking treatments were: Gibberalic acid (GA3) and Thiourea each at 50, 100, 150, 200, 250, and 300 ppm and Potassium nitrate (KNO3) at 5,000, 10,000, 15,000, 20,000, 25,000, and 30,000 ppm (24 h soaking). Germination (G) percentage and germination energy (GE) of E. dracunculoides was maximum (89 and 22, respectively) at 250 ppm concentration of GA3 and 81.50 and 11.50 at 15000 ppm concentration of KNO3. Thiourea at 250 and 300 ppm resulted in maximum G percentage (51) and GE (25.50) of E. dracunculoides, whereas the G percentage and GE of Astragalus spp. were maximum (28 and 19, respectively) at the lowest concentration of GA3 (50 ppm). On the other hand, 5000 ppm and 150 ppm concentration of KNO3 and Thiourea showed maximum GE (19.5) and G percentage (28) of Astragalus spp., respectively. Overall, effective dormancy breaking chemical against E. dracunculoides was GA3 (250 ppm) while in Astragalus spp. none of chemicals showed very impressive results. These results showed that both weeds' seeds have dormancy in their habit. Hot water treatment and the above mentioned chemicals (best concentrations) when used with 4...

Dormancy and germination of Annona macroprophyllata (Annonaceae): the importance of the micropylar plug and seed position in the fruits

González-Esquinca,Alma Rosa; De-la-Cruz-Chacón,Iván; Domínguez-Gutú,Luz María
Fonte: Sociedad Botánica de México A.C. Publicador: Sociedad Botánica de México A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 EN
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Annona macroprophyllata (papausa or ilama) is an economically important species of fruit that is consumed in large quantities in Central America and is considered to have the finest flavour of all of the custard apples (Annonaceae). This species presents propagation problems including the six-month dormancy of the seeds, which has not been fully explained. Among the factors affecting the germination of Annona seeds are the position inside of the fruit and the presence of a micropylar woody plug. The present work addresses the importance of these factors in the germination and dormancy of this species, using a randomised design with seeds from 169 fruits of the white variety of Annona macroprophyllata. The fruits were divided into three sections (basal, middle, and apical) in which seeds were evaluated for nine months with the following parameters: the size and weight of the seeds and the viability and germination percentage considering the presence or absence of the micropylar plug. The results show no correlation between the breaking of dormancy and either the position of the seeds in the fruit or the micropylar plug, but they do establish the importance of the micropylar plug for germination. The breaking of dormancy requires storage for the length of the dry season in the tropical deciduous forest...