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Heat tolerance and the effects of shade on the behavior of Simmental bulls on pasture

TITTO, Cristiane Goncalves; TITTO, Evaldo Antonio Lencioni; TITTO, Rafael Martins; MOURAO, Gerson Barreto
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.433496%
The objectives were to assess the degree of thermolysis capacity as a characteristic of heat tolerance of the Simmental beef cattle and evaluate the effects of shade and shade type (artificial: AS, trees: TS, or no shade: NS) on daily behavior patterns during summer. Black globe temperature (BGT) was different under the two types of shade (P < 0.05) and was lower under the TS (P < 0.01) and under AS (P > 0.01) than average BGT in the sun. Animals when in AS used more intensely the shade (P = 0.002) mostly lying down under it (10.00-14.00 hours), while time standing was similar (P = 0.107) between TS and NS. Bulls without shade (NS) spent significantly more time at the water trough and most part of the day standing idle (72.4%, 10.1 h/14 h). TS bulls spent more time grazing/standing (P < 0.001). The Simmental bulls that were in TS and AS spent more time ruminating than bulls that stay without shade (NS). The availability of shade changes grazing, rumination and idling behavior of cattle in response to environmental conditions. Shade provided by trees can be more efficient than artificial shading as cattle spent more time grazing when tree shade was available. Thermolysis capacity can be used to select heat-tolerant animals.

Comportamento de touros da raça Simental à pasto com recurso de sombra e tolerância ao calor; Behavior of Simental bulls under grazing with shade resources and heat tolerance

Titto, Cristiane Gonçalves
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 17/01/2007 Português
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O presente trabalho teve como objetivo avaliar o comportamento de pastejo de bovinos de corte com e sem acesso a recursos de sombreamento e determinar o Índice de Tolerância ao Calor Individual (ITCI) e uma possível relação com o uso da sombra. Foram utilizados 8 touros da raça Simental, com 80 meses. As observações de comportamento ocorreram do nascer ao pôr do sol, a cada 15 minutos, pelo método focal. Os comportamentos observados foram: Posição (ao sol, à sombra natural, à sombra artificial); Postura (em pé, deitado) e Atividade (em pastejo, em ruminação, em deslocamento, em ócio), em três tratamentos: Sombra Natural (SN), Sombra Artificial (SA) e sem sombra (SS). Numa segunda fase os animais foram submetidos ao Teste de Tolerância ao Calor e foi determinado o ITCI. O índice de globo negro e umidade médio foi de 88,5. O uso da sombra foi maior no SA em relação ao SN (43% e 32%) iniciando mais cedo e deixando-a mais tarde (10h00 e 16h00 no SA, 10h30 e 15h00 no SN). Os animais permaneceram mais tempo em pé no SS, seguido pelo SN e pelo SA (86,5%, 80,6%, 73,7%). No tratamento SN os animais pastejaram 65,4% do tempo total de observação, ruminaram 18,3%, permaneceram em ócio 15,9% e a atividade de deslocamento tomou 0...

Cultivo em campo de Coffea arabica L. cv. Obatã a pleno sol x sombreamento parcial: avaliações bioquímicas, fisiológicas e nutricionais; Field growth of Coffea arabica L. cv. Obatã under full x partial shade: biochemical, physiological and nutritional evaluations

Gonçalves, Gislei Cristina
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 13/04/2007 Português
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37.14365%
Plantas de café Arábicas com 4,5 anos de idade foram comparadas de agosto a dezembro crescendo a pleno sol e sob condições de sombreamento natural. As plantas apresentaram diferenças significativas em termos de crescimento e aspectos fisiológicos e bioquímicos O fornecimento de nitrogênio no mês de outubro proporcionou um aumento significativo nos teores de aminoácidos totais e na atividade da redutase do nitrato. As folhas de plantas crescendo em condições de sombreamento natural apresentaram maior peso fresco a que pleno sol. O teor de proteínas totais decresceu abruptamente a partir do mês 10 em todas as plantas analisadas, época em coincidiu com o inicio do enchimento dos grãos. O aumento nos teores de aminoácidos totais também foi acompanhado por um aumento nos dias de chuva, na precipitação e também na radiação global. Não houve efeito significativo com relação á localização da folhas (parte superior x parte inferior) nos aspectos analisados. O fornecimento de nitrogênio no mês 10 não alterou a concentração de clorofila medida pelo clorofilômetro SPAD, e a clorofila total extraída não se alterou significativamente até o mês 11 exceto nas plantas de sol as folhas do parte superior tiveram uma maior síntese no mês 9. No mês 12 houve um aumento nas taxas de clorofila em todos os tratamentos. Os teores de N foliar tiveram correlação positiva com as leituras de clorofila analisadas pelo SPAD...

Effect of shade and water sprinkling on physiological responses and milk yields of Holstein cows in a semi-arid region

Domingos, H. G T; Maia, A. S C; Souza, J.B.F; Silva, R. B.; Vieira, F. M C; Silva, R. G.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 169-174
Português
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The effects of shading and water sprinkling on physiological responses and milk production were studied in Holstein cows managed in an equatorial semi-arid region. Five cows were observed for 36 days during May and June 2009. We studied the effects of sun, shade, shade plus single sprinkling, shade plus sprinkling every 2. h and shade plus sprinkling every hour on physiological responses, i.e., rectal temperature, coat surface temperature and respiratory rate, and on milk production. Environmental variables, i.e., air temperature, black globe temperature, mean radiant temperature, relative humidity and wind speed, were recorded every 30. min throughout the observation period. The statistical analysis utilized a 5×5 replicated latin square, and the results showed reduced values in physiological variables in cows that were protected from short wave radiation and that received water sprinkling; milk yield increased by approximately 3.5. kg in such animals relative to those not receiving such treatment. However, the milk yield for the morning milking presented similar mean values regardless of whether the animals received shading and sprinkling benefits, which indicates that frequency of sprinkling and amount of time (permanence) in the shade were critical for the effect on milk yield. © 2013 Elsevier B.V.

Behavioral aspects of Caracu and Red Angus cattle breeds in a pasture with shade and water immersion

Geraldo, A. C. A. P. M.; Pereira, Alfredo Manuel Franco; Nogueira Filho, J.C.M.; Titto, E.A.L.
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica
Português
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37.311414%
The shade is an important resource in the extensive production systems in tropical regions. The aim of this study is to understand through behavioral analysis, the preferences of animals for resources for environmental protection. The experiment was conducted in the Biometeorology and Ethology Laboratory of FZEA-USP. Six male of Caracu and Red Angus cattle breeds were used. The animals were submitted to 2 different treatments: availability of artificial shade and water for immersion and availability of water for immersion. The observations of the behavioral patterns were recorded using the focal sampling method every 15 minutes (12h/day). The observed positions were: in the sun, under the shade and in the water. The posture observed were: standing, lying down and behavioural activities were grazing, ruminating and rest. The data concerning to the time spent in different behaviors and different positions were analyzed by the multifactorial variance (ANOVA-GLM). The fixed factors used were the breed and treatment. The results had shown that grazing activity was the behavior in which both breeds had spending more time (especially in the cooler periods), followed by ruminating in the Caracu and by resting in the Red Angus. The results also had shown that shade can be used as a shelter against solar radiation as well against rain. The Caracu had presented a clear preference for the shade...

Physiological aspects of sun and shade leaves of Lithraea molleoides (Vell.) Engl. (Anacardiaceae)

Dias,Jaqueline; Pimenta,José Antonio; Medri,Moacyr Eurípedes; Boeger,Maria Regina Torres; Freitas,Claudinei Toledo de
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 Português
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The aim of this work was to compare the physiological parameters of sun and shade leaves of a specimen of L. molleoides. The higher-positional leaves, classified as sun leaves, presented similar photosynthetic rate, lower chlorophyill contents (a, b and total), same a chlorophyll /b chlrorophyll rate, lower transpiratory rate, same stomatal conductance and intercellular concentration of CO2 as the lower-positional leaves, classified as shade leaves. Nutrient concentration, except for Ca and Mg, was the same for both sun and shade leaves.The physiological parameter responses indicated that although receiving lower light intensity, the shade leaves had the same capacity to grow and develop as the sun leaves.

Leaf optical properties as affected by shade in saplings of six tropical tree species differing in successional status

Souza,Rogéria Pereira; Válio,Ivany F. M.
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2003 Português
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Tree species differing in successional status may present different responses to shade. Adjustments at leaf level may affect their optical properties, leading to changes in PAR (photosynthetically active radiation) absorbance. The aim of this study was to evaluate leaf optical properties as affected by understory shade in saplings of six tropical tree species differing in successional status and degree of shade tolerance. Chlorophyll content and specific leaf area (SLA) were also evaluated. The effects of shade on leaf optical properties and chlorophyll content differed among the studied species, whereas increased SLA was a common response for all species, reflecting the occurrence of thinner leaves under shade. The three studied shade-tolerant species - Esenbeckia leiocarpa, Myroxylon peruiferum and Hymenaea courbaril - presented a greater PAR absorbance under shade. The response of the shade-intolerant species was varied. While Schizolobium parahyba also showed a greater PAR absorbance under shade, Chorisia speciosa did not alter its spectral properties and Cecropia pachystachya presented an opposite pattern, with smaller absorbance under shade. Increases in leaf chlorophyll content were significant in the shade-tolerant species...

Photosynthetic induction and activity of enzymes related to carbon metabolism: insights into the varying net photosynthesis rates of coffee sun and shade leaves

Martins,Samuel Cordeiro Vitor; Detmann,Kelly Coutinho; Reis,Josimar Vieira dos; Pereira,Lucas Felisberto; Sanglard,Lílian Maria Vincis Pereira; Rogalski,Marcelo; DaMatta,Fábio Murilo
Fonte: Sociedade Brasileira de Fisiologia Vegetal Publicador: Sociedade Brasileira de Fisiologia Vegetal
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 Português
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The shade leaves of coffee (Coffea arabica L.) apparently retain a robust photosynthetic machinery that is comparable to that of sun leaves and can fix CO2 at high rates when subjected to high light intensities. This raises the question of why the coffee plant would construct such a robust photosynthetic machinery despite the low photosynthetic rates achieved by the shade leaves at low light supply. Here, we grew coffee plants at 100% or 10% full sunlight and demonstrated that the shade leaves exhibited faster photosynthetic induction compared with their sun counterparts, in parallel with lower loss of induction states under dim light, and were well protected against short-term sudden increases in light supply (mimicking sunflecks). These findings were linked to similar photosynthetic capacities on a per mass basis (assessed under nonlimiting light), as well as similar extractable activities of some enzymes of the Calvin cycle, including Rubisco, when comparing the shade and sun leaves. On the one hand, these responses might represent an overinvestment of resources given the low photosynthetic rates of the shade leaves when light is limiting; on the other hand, such responses might be associated with a conservative behavior linked to the origin of the species as a shade-dwelling plant...

Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits.

GEROMEL, C.; FERREIRA, L. P.; DAVRIEUX, F.; GUYOT, B.; RIBEYRE, F.; SCHOLZ, M. B. dos S.; PEREIRA, L. F. P.; VAAST, P.; POT, D.; LEROY, T.; ANDROCIOLI FILHO, A.; VIEIRA, L. G. E.; MAZZAFERA, P.; MARRACCINI, P.
Fonte: PLANT PHYSIOLOGY AND BIOCHEMISTRY, v.46, n.5-6, p.569-579, may-june, 2008. Publicador: PLANT PHYSIOLOGY AND BIOCHEMISTRY, v.46, n.5-6, p.569-579, may-june, 2008.
Tipo: Artigo em periódico indexado (ALICE) Formato: 569-579
Português
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Coffee fruits grown in shade are characterized by larger bean size than those grown under full-sun conditions. The present study assessed the effects of shade on bean characteristics and sugar metabolism by analyzing tissue development, sugar contents, activities of sucrose metabolizing enzymes and expression of sucrose synthase-encoding genes in fruits of coffee (Coffea arabica L.) plants submitted to full-sun (FS) and shade (SH) conditions. Evolution of tissue fresh weights measured in fruits collected regularly from flowering to maturation indicated that this increase is due to greater development of the perisperm tissue in the shade. The effects of light regime on sucrose and reducing sugar (glucose and fructose) contents were studied in fresh and dry coffee beans. Shade led to a significant reduction in sucrose content and to an increase in reducing sugars. In pericarp and perisperm tissues, higher activities of sucrose synthase (EC 2.4.1.13) and sucrose-phosphate synthase (SPS: EC 2.4.1.14) were detected at maturation in the shade compared with full sun. These two enzymes also had higher peaks of activities in developing endosperm under shade than in full sun. It was also noted that shade modified the expression of SUS-encoding genes in coffee beans; CaSUS2 gene transcripts levels were higher in SH than in FS. As no sucrose increase accompanied these changes...

Effects of shade on the development and sugar metabolism of coffee (Coffea arabica L.) fruits.

GEROMEL, C.; FERREIRA, L. P.; DAVRIEUX, F.; GUYOT, B.; RIBEYRE, F.; SCHOLZ, M. B. dos S.; PEREIRA, L. F. P.; VAAST, P.; POT, D.; LEROY, T.; ANDROCIOLI FILHO, A.; VIEIRA, L. G. E.; MAZZAFERA, P.; MARRACCINI, P.
Fonte: PLANT PHYSIOLOGY AND BIOCHEMISTRY, v.46, n.5-6, p.569-579, may-june, 2008. Publicador: PLANT PHYSIOLOGY AND BIOCHEMISTRY, v.46, n.5-6, p.569-579, may-june, 2008.
Tipo: Artigo em periódico indexado (ALICE) Formato: 569-579
Português
Relevância na Pesquisa
37.373325%
Coffee fruits grown in shade are characterized by larger bean size than those grown under full-sun conditions. The present study assessed the effects of shade on bean characteristics and sugar metabolism by analyzing tissue development, sugar contents, activities of sucrose metabolizing enzymes and expression of sucrose synthase-encoding genes in fruits of coffee (Coffea arabica L.) plants submitted to full-sun (FS) and shade (SH) conditions. Evolution of tissue fresh weights measured in fruits collected regularly from flowering to maturation indicated that this increase is due to greater development of the perisperm tissue in the shade. The effects of light regime on sucrose and reducing sugar (glucose and fructose) contents were studied in fresh and dry coffee beans. Shade led to a significant reduction in sucrose content and to an increase in reducing sugars. In pericarp and perisperm tissues, higher activities of sucrose synthase (EC 2.4.1.13) and sucrose-phosphate synthase (SPS: EC 2.4.1.14) were detected at maturation in the shade compared with full sun. These two enzymes also had higher peaks of activities in developing endosperm under shade than in full sun. It was also noted that shade modified the expression of SUS-encoding genes in coffee beans; CaSUS2 gene transcripts levels were higher in SH than in FS. As no sucrose increase accompanied these changes...

Valida????o e reprodutibilidade da an??lise subjetiva no diagn??stico da cor dent??ria; Validity and reproducibility of the subjective evaluation used for tooth shade diagnosis

MEIRELES, S??nia Saeger
Fonte: Universidade Federal de Pelotas; Odontologia; Programa de P??s-Gradua????o em Odontologia; UFPel; BR Publicador: Universidade Federal de Pelotas; Odontologia; Programa de P??s-Gradua????o em Odontologia; UFPel; BR
Tipo: Dissertação Formato: application/pdf
Português
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37.311414%
The objective of this study was to examine the validity and reproducibility of the subjective evaluation used for tooth shade diagnosis. This study used the same ninety-two individuals selected for a randomized clinical trial comparing two carbamide peroxide bleaching agents. The shade of the six upper anterior teeth of these subjects was determined before starting the clinical trial. One operator performed the objective shade determination of all upper anterior teeth (n= 552) using a spectrophotometer (Vita Easyshade, VITA). Then, two calibrated examiners subjectively determined the teeth shade of the patients following their arrival time for the dental appointment. The visual (subjective) analysis was performed using a conventional shade guide (Vitapan Shade Guide, VITA). The reproducibility was evaluated using the kappa (k) coefficient, considering the shades grouped in two categories (light and dark) or using the pondered kappa (Kw), which considers all the 16 shades of the guide. The sensibility and specificity were determined using the spectrophotometer as the gold-standard. The faithful of the subjective evaluation for the two categories of shades was substantial (K= 0.69) and mild (Kw= 0.33) when considering all shades. The sensibility of the visual analysis was 86.9% and the specificity was 81.9%. The visual analysis of the shades was considered a valid method...

Shade promotes thorn development in a tropical liana, Artabotrys hexapatalus (Annonaceae)

Lee, David W.; Fisher, Jack B.; Posluszny, Usher
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Português
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The liana Artabotrys hexapetalus (L.f.) Bhand., which is widely planted in the Tropics and native to African rain forests, produced new reiterations (new leader shoots) normally and after damage induced by Hurricane Andrew (August 24, 1992). In each new orthotropic shoot, there is a gradient in lateral branch structures from basal thorns, to vegetative leafy branches, to distal leafy flowering branches. We noted that reiterations developing in shade had more thorns than similar reiterations developing in full sun. Tents with clear (66% photosynthetically active radiation [PAR]) and shaded plastic film (12%–14% PAR) were placed over nodes when the axillary buds began to expand to produce reiteration shoots. After 2 mo of growth inside the tents and in the open, the types of lateral outgrowths (thorn vs. branch) were recorded. Shoots in spectrally neutral shade (red to far red of full sun) and spectrally altered shade (red to far red of canopy shade) produced significantly more thorns at the lower nodes of the shoots as compared to those in full sun. Shoots in control clear plastic tents were the same as those in full sun. We conclude that the fate of lateral bud development is controlled by irradiance (light level) but not by light quality. Increased thorn production in shade could be advantageous to plants growing in the deep shade of rain forests. Thorns in the self-shaded regions of the plant...

Simulating Forest Shade to Study the Developmental Ecology of Tropical Plants: Juvenile Growth in Three Vines in India

Lee, David W.
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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Both light quantity and quality affect the development and autoecology of plants under shade conditions, as in the understorey of tropical forests. However, little research has been directed towards the relative contributions of lowered photosynthetic photon flux density (PPFD) versus altered spectral distributions (as indicated by quantum ratios of 660 to 730 nm, or R:FR) of radiation underneath vegetation canopies. A method for constructing shade enclosures to study the contribution of these two variables is described. Three tropical leguminous vine species (Abrus precatorius L., Caesalpinia bondicela Fleming and Mucuna pruriens (L.) DC.) were grown in two shade enclosures with 3-4% of solar PPFD with either the R:FR of sunlight (1.10) or foliage shade (0.33), and compared to plants grown in sunlight. Most species treated with low R:FR differed from those treated with high R:FR in (1) percent allocation to dry leaf weight, (2) internode length, (3) dry stem weight/length, (4) specific leaf weight, (5) leaf size, and (6) chlorophyll a/b ratios. However, these plants did not differ in chlorophyll content per leaf dry weight or area. In most cases the effects of low R:FR and PPFD were additional to those of high R:FR and low PPFD. Growth patterns varied among the three species...

Interactive effects of drought and shade on three arid zone chenopod shrubs with contrasting distributions in relation to tree canopies

Prider, J.; Facelli, J.
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em //2004 Português
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1. Plants that grow beneath trees in arid systems may frequently experience both water and light limitation, although protection from high radiation loads during drought may compensate for a loss of productivity due to reduced light availability when water is plentiful. 2. We examined the effects of shading, during an imposed water deficit, on the carbon gain, stomatal conductance (gs) and shoot water potential ({Psi}s) of seedlings of three shrubs: Atriplex vesicaria (Heward ex Benth.), a C4 species, and Enchylaena tomentosa (R. Br.) and Rhagodia spinescens (R. Br.), which are restricted to shaded sites beneath trees. 3. Under conditions of limiting water, photosynthetic rates measured at saturating light (Amax) were negative in high-light grown Enchylaena plants but remained positive in shade-grown plants. When water was not limiting, Amax was reduced in shade-grown Atriplex but shade did not affect carbon gain in the other two species. 4. Atriplex {Psi}s was higher in shaded than in unshaded plants, but in unshaded plants positive carbon gain was maintained at {Psi}s below -10 MPa. Stomatal conductance and Amax decreased more slowly with increasing water deficit in shaded conditions in all species. 5. Atriplex was tolerant of a broader range of light and soil moisture conditions than Enchylaena...

Identification of REVOLUTA target genes uncovers a link between leaf patterning and shade-induced growth responses; Identifizierung von REVOLUTA Zielgenen zeigt eine Verbindung zwischen Blattmusterbildung und schatteninduzierten Wachstumsprozessen auf

Brandt, Ronny
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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37.215105%
Plants are sessile organisms and thus have to cope with unfavorable growth conditions. To survive in an ever-changing environment, they have to constantly align their growth behavior to biotic and abiotic factors. In their struggle for water, nutrients and light in a highly competitive environment, plants have evolved gene- and hormone-regulatory networks enabling them to counteract suboptimal conditions by inducing elongation growth. In this thesis I show that the interplay of homeodomain-leucine zipper (HD-ZIP) transcription factors and plant hormones act as an adjusting screw between the inherent growth programs and the outer world. REVOLUTA, a class III homeodomain-leucine-zipper (HD-ZIPIII) transcription factor, plays a crucial role in many polarity-associated patterning processes. Using a ChIP-Seq (Chromatin-Immuno-Precipitation-Sequencing) approach we were able to identify a number of direct REVOLUTA target genes. Some of these targets are involved in controlling developmental processes, while a significant number is involved in responding to abiotic stimuli. Two of the identified target genes are: TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1 (TAA1) und YUCCA5 (YUC5), whose gene products are involved in biosynthesis of auxin. Additionally...

Influence of shade and irradiation time on the hardness of composite resins

Della Bona,Álvaro; Rosa,Vinícius; Cecchetti,Dileta
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 Português
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37.26913%
This study tested the following hypotheses: 1. increasing light irradiation time (IT) produces greater values of superficial hardness on different depths (0 and 3 mm); and 2. a dark shade composite (A3) needs longer IT than a light shade composite (A1) to produce similar hardness. Disk-shaped specimens (n=24 per shade) were fabricated using a 3-mm-thick increment of composite resin (Z100). Specimens were randomly assigned to 3 groups (n=8) according to the IT (400 mW/cm2) at the upper (U) surface: A1-10 and A3-10: 10 s; A1-20 and A3-20: 20 s; A1-40 and A3-40: 40 s. Specimens were stored in black lightproof containers at 37ºC for 24 h before indentation in a hardness tester. Three Vickers indentations were performed on the U and lower (L) surfaces of each specimen. The indent diagonals were measured and the hardness value calculated. The results were analyzed statistically by ANOVA and Tukey's test (alpha=0.05). Statistically significant differences were found between U and L surfaces of each composite shade-IT combination (p=0.0001) and among the ITs of same shade-surface combination (p=0.0001), except between groups A1-20U and A1-40U, confirming the study hypothesis 1 and partially rejecting the hypothesis 2.

Minimum water input event for seedling emergence of three native perennial grasses of the Central Monte desert (Argentina) influenced by the effect of shade and the season of the year; Pulso mínimo de agua para la emergencia de plántulas de tres especies de gramíneas perennes nativas del Monte Central (Argentina), influenciado por el efecto de la sombra y la estación del año

Greco, Silvina Alicia; Sartor, Carmen Elena; Villagra, Pablo Eugenio
Fonte: Universidad Nacional de Cuyo Publicador: Universidad Nacional de Cuyo
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Português
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In deserts, seedling emergence occurs only after precipitation threshold has been exceeded, however, the presence of trees modifies microenvironmental conditions that might affect the effectiveness of a water pulse. In the Monte desert, Prosopis flexuosa trees generate different micro-environmental conditions that might influence grass seedlings establishment. The objective of this work was: a) to know the effective minimum water input event that triggers the emergence of native perennial grass seedlings; b) to relate this fact with the effect of the shade of P. flexuosa canopy and the seasonal temperatures. Three important forage species of the Monte were studied: Pappophorum caespitosum and Trichloris crinita, with C4, and Jarava ichu, with C3 metabolism. Each season, seeds of these species were sown in pots placed at two light conditions: shade (similar to P. flexuosa cover) and open area, and with seven irrigation treatments (0, 10, 20, 30, 40, 2*10 and 3*10 mm). J. ichu did not emerge in any of the treatments. Significant seedling emergence was registered for P. caespitosum and T. crinita in shade conditions with 40 mm irrigation treatment in summer. Since 40 mm precipitation events are infrequent in the Monte, seedling emergence for these species would be restricted to exceptional rainy years. The facilitating effect of P. flexuosa shade would be important during the hot season.; En los desiertos...

Rol de las proteínas B-box en las respuestas de escape al sombreado en Arabidopsis thaliana; Role of B-Box proteins in the shade avoidance responses in Arabidopsis thaliana

Crocco, Carlos Daniel
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2012 Português
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Cuando las plantas crecen a altas densidades perciben la presencia temprana de plantas vecinas sensando los cambios en la calidad de luz que las rodea. Esta percepción es mediada principalmente por los fitocromos, una familia de fotorreceptores que detectan una reducción en la relación rojo:rojo lejano (R:RL) causada por la proximidad de plantas vecinas induciendo un conjunto de respuestas morfo-fisiológicos tales como la elongación de hipocotilo y tallo, dominancia apical, aceleración de la floración, entre otros. Este conjunto de respuestas plásticas constituye “el síndrome de escape al sombreado”, SAS (del inglés, Shade Avoidance Syndrome). Si bien en los últimos años se ha comenzado a comprender los mecanismos moleculares involucrados en la SAS, aún nuestro conocimiento es escaso. En esta tesis estudiamos la función de las proteínas B-Box (BBX) en la señalización de la SAS en plántulas de Arabidopsis thaliana, enfocando nuestra atención en un subgrupo de esta familia que se caracteriza por presentar un doble dominio B-box en su región amino terminal. La caracterización fisiológica de algunos mutantes simples nos permitió demostrar que BBX18 y BBX24 promueven, mientras que BBX19, BBX21, BBX22 inhiben la respuesta de elongación por sombra. En particular...

Minimum water input event for seedling emergence of three native perennial grasses of the Central Monte desert (Argentina) influenced by the effect of shade and the season of the year

Fonte: Revista de la Facultad de Ciencias Agrarias. Universidad Nacional de Cuyo Publicador: Revista de la Facultad de Ciencias Agrarias. Universidad Nacional de Cuyo
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 Português
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In deserts, seedling emergence occurs only after precipitation threshold has been exceeded, however, the presence of trees modifies microenvironmental conditions that might affect the effectiveness of a water pulse. In the Monte desert, Prosopis flexuosa trees generate different micro-environmental conditions that might influence grass seedlings establishment. The objective of this work was: a) to know the effective minimum water input event that triggers the emergence of native perennial grass seedlings; b) to relate this fact with the effect of the shade of P. flexuosa canopy and the seasonal temperatures. Three important forage species of the Monte were studied: Pappophorum caespitosum and Trichloris crinita, with C4, and Jarava ichu, with C3 metabolism. Each season, seeds of these species were sown in pots placed at two light conditions: shade (similar to P. flexuosa cover) and open area, and with seven irrigation treatments (0, 10, 20, 30, 40, 2*10 and 3*10 mm). J. ichu did not emerge in any of the treatments. Significant seedling emergence was registered for P. caespitosum and T. crinita in shade conditions with 40 mm irrigation treatment in summer. Since 40 mm precipitation events are infrequent in the Monte, seedling emergence for these species would be restricted to exceptional rainy years. The facilitating effect of P. flexuosa shade would be important during the hot season.

Woody plant diversity and structure of shade-grown-coffee plantations in Northern Chiapas, Mexico

Soto-Pinto,Lorena; Romero-Alvarado,Yolanda; Caballero-Nieto,Javier; Segura Warnholtz,Gerardo
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2001 Português
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Shade-grown coffee is an agricultural system that contains some forest-like characteristics. However, structure and diversity are poorly known in shade coffee systems. In 61 coffee-growers’ plots of Chiapas, Mexico, structural variables of shade vegetation and coffee yields were measured, recording species and their use. Coffee stands had five vegetation strata. Seventy seven woody species mostly used as wood were found (mean density 371.4 trees per hectare). Ninety percent were native species (40% of the local flora), the remaining were introduced species, mainly fruit trees/shrubs. Diametric distribution resembles that of a secondary forest. Principal Coordinates Analysis grouped plots in four classes by the presence of Inga, however the majority of plots are diverse. There was no difference in equitability among groups or coffee yields. Coffee yield was 835 g clean coffee per shrub, or ca. 1668 kg ha-1. There is a significant role of shade-grown coffee as diversity refuge for woody plants and presumably associated fauna, as well as an opportunity for shade-coffee growers to participate in the new biodiversity-friendly-coffee market