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Morphogenetic and structural characteristics of andropogon grass submitted to different cutting heights; Características morfogênicas e estruturais do capim-andropógon submetido a diferentes alturas de corte

SOUSA, Braulio Maia de Lana; NASCIMENTO JÚNIOR, Domicio do; SILVA, Sila Carneiro da; MONTEIRO, Hélida Christhine de Freitas; RODRIGUES, Carlindo Santos; FONSECA, Dilermando Miranda da; SILVEIRA, Márcia Cristina Teixeira da; SBRISSIA, André Fischer
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.44%
This work was performed aiming to evaluate the morphogenetic and structural characteristics of Andropogon gayanus cv. Planaltina species submitted to three cutting heights (20, 27 and 34 cm). The three cutting heights were allocated in experimental units (12 m²) in a complete randomized block design with three replications. The cuts were done when the light interception by the sward reached 95%. At this moment, the sward height revealed itself constant with values close to 50 cm. The lowest cutting height (20 cm) influenced negatively the final leaf blade length, the number of live leaves, the leaf lifespan, the stem elongation rate and the tiller population density, and it influenced positively the phyllochron and the leaf senescence rate. Probably, cuts at 20 cm height caused a high decapitation and death of the tillers. The worst growth conditions in addition to the blossom of this specie occurred during fall resulted in higher stem elongation rates and number of live leaves, and lower phyllochron, final leaf blade length, and leaf lifespan. The sward height can be used as a practical and efficient criterion in the management of andropogon grass. Under intermittent management conditions, the regrowth of andropogon grass must be interrupted when the sward reaches 50 cm height...

Morphogenesis in guinea grass pastures under rotational grazing strategies

Montagner, Denise Baptaglin; Nascimento Junior, Domicio do; Sousa, Braulio Maia de Lana; Vilela, Helio Henrique; Silveira, Marcia Cristina Teixeira da; Euclides, Valeria Pacheco Batista; Silva, Sila Carneiro da; Carloto, Marciele Neves
Fonte: REVISTA BRASILEIRA ZOOTECNIA; VIÇOSA Publicador: REVISTA BRASILEIRA ZOOTECNIA; VIÇOSA
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.33%
This study was conducted in order to evaluate the morphogenetic and structural characteristics of guinea grass cv. Mombasa under three post-grazing heights (intense - 30 cm, lenient - 50 cm and variable - 50 in spring-summer and 30 cm in autumn-winter) when sward light interception reached 95% during regrowth. Post-grazing heights were allocated to experimental units (0.25 ha) in a completely randomized block design with three replications. Post-grazing heights affected only leaf elongation rate and the number of live leaves. Pastures managed with variable post-grazing height showed higher leaf elongation rate in the summer of 2007. This management strategy also resulted in a higher number of live leaves. During the spring of 2006, plants showed lower leaf elongation rate, leaf appearance rate and number of live leaves, and greater phyllochron and leaf lifespan. In contrast, during the summer of 2007, the leaf appearance rate, leaf elongation rate, number of live leaves, and final leaf length were greater while phyllochron, stem elongation rate, and leaf senescence rate were lower. The management of the guinea grass cv. Mombasa with intense or variable post-grazing height throughout the year seems to represent an interesting management target...

Efeitos da adubação potássica sobre a adaptação à seca do Eucalyptus grandis; Effects of potassic fertilization on drought adaptation in Eucalyptus grandis plantations

Laclau, Patricia Renee Françoise Battie
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 25/10/2013 PT
Relevância na Pesquisa
36.29%
Com a continuação do aquecimento global, prevê-se o aumento dos períodos de seca, um dos mais importantes fatores abióticos a afetar o crescimento dos eucaliptos no Brasil. Nessa direção, as práticas silviculturais poderiam adaptar-se para favorecer os mecanismos de adaptação das árvores à seca. Assim, na Estação Experimental de Itatinga, foram avaliados os efeitos da adubação potássica sobre os aspectos produtivos e fisiológicos de um povoamento de Eucalyptus grandis, em primeira rotação, submetido à exclusão parcial de chuva durante trinta meses após o plantio. O dispositivo experimental foi um split plot, com três blocos completos e quatro tratamentos: dois regimes hídricos (100% e 63% das chuvas, com exclusão parcial artificial) e duas doses de K (0 e 4,5 kmol ha-1). A meta foi avaliar a influência da nutrição potássica sobre as características e a atividade fotossintética das folhas. A transpiração foi medida por sensores de fluxo de seiva para estimar a eficiência de transpiração do povoamento. O potencial foliar e as trocas gasosas foliares foram monitorados, enquanto os valores de 'delta'13C do floema foram medidos, para avaliar o estado hídrico e o funcionamento estomático das árvores...

Influence of potassium and sodium nutrition on leaf area components in Eucalyptus grandis trees

Battie-Laclau, Patricia; Laclau, Jean-Paul; Piccolo, Marisa de Cassia; Arenque, Bruna Cersózimo; Beri, Constance; Mietton, Lauriane; Muniz, Marta R. Almeida; Jordan-Meille, Lionel; Buckeridge, Marcos Silveira; Nouvellon, Yann; Ranger, Jacques; Bouillet,
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 19-35
ENG
Relevância na Pesquisa
46.34%
Background and Aims: Recent studies showed a positive tree response to Na addition in K-depleted tropical soils. Our study aimed to gain insight into the effects of K and Na fertilizations on leaf area components for a widely planted tree species. Methods: Leaf expansion rates, as well as nutrient, polyol and soluble sugar concentrations, were measured from emergence to abscission of tagged leaves in 1-year-old Eucalyptus grandis plantations. Leaf cell size and water status parameters were compared 1 and 2 months after leaf emergence in plots with KCl application (+K), NaCl application (+Na) and control plots (C). Results: K and Na applications enhanced tree leaf area by increasing both leaf longevity and the mean area of individual leaves. Higher cell turgor in treatments +K and +Na than in the C treatment resulting from higher concentrations of osmotica contributed to increasing both palisade cell diameters and the size of fully expanded leaves. Conclusions: Intermediate total tree leaf area in treatment +Na compared to treatments C and +K might result from the capacity of Na to substitute K in osmoregulatory functions, whereas it seemed unable to accomplish other important K functions that contribute to delaying leaf senescence. © 2013 Springer Science+Business Media Dordrecht.

CONTRIBUTION OF BASAL AND AERIAL TILLERS IN DYNAMICS OF HERBAGE PRODUCTION OF SIGNALGRASS AFTER GRAZING DEFERRED

Rozalino Santos, Manoel Eduardo; St Anna e Castro, Marina Reis; Gouveia, Sabrina Carraro; Gomes, Virgilio Mesquita; Fonseca, Dilermando Miranda da; Santana, Sabrina Saraiva
Fonte: Univ Federal Uberlandia Publicador: Univ Federal Uberlandia
Tipo: Artigo de Revista Científica Formato: 424-430
POR
Relevância na Pesquisa
36.29%
During the spring, the understanding of regrowth in basal and aerial tillers of deferred pasture in winter it is necessary. Thus, the objective was to evaluate the morphogenesis and herbage accumulation during spring in Brachiaria decumbens cv. Basilisk (signalgrass) pasture used under deferred grazing in winter. The basal and aerial tillers in same pasture were evaluated. The signalgrass was managed with grazing cattle and with an average height of 25 cm. The randomized block design with three replications was adopted. The leaf appearance rate, phyllochron and the numbers of expanded, expanding and live leaves did not differ between basal and aerial tillers. The aerial tiller possessed lower rates of leaf senescence, of leaf elongation and of stem elongation, as well as lower number of dead leaf and stem and leaf lamina lengths, compared to basal tiller. The leaf lifespan was higher in aerial tillers than at basal. The basal tiller also contributed to higher rates of tissue growth and forage accumulation in pasture when compared to aerial tiller. After deferred grazing during the spring, the aerial tiller has low participation in forage production of signalgrass pasture.

Herbage utilisation efficiency of continuously stocked marandu palisade grass subjected to nitrogen fertilisation

Pereira,Lilian Elgalise Techio; Paiva,Adenilson José; Guarda,Vitor Del’Álamo; Pereira,Priscila de Mesquita; Caminha,Fábio Olegário; Silva,Sila Carneiro da
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2015 EN
Relevância na Pesquisa
36.44%
Nitrogen fertiliser accelerates plant growth and increases herbage utilisation efficiency in continuously stocked temperate grass swards, indicating greater herbage production and harvest efficiency. There is no similar evidence, however, for tropical pastures. In this study we evaluated the morphogenetic responses, the patterns of defoliation and the efficiency of herbage utilisation of continuously stocked marandu palisade grass (Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. Marandu) maintained at 30 cm by cattle and fertilised with nitrogen. Treatments corresponded to four measures of nitrogen application (0, 150, 300 and 450 kg ha–1), and were assigned to experimental units (1,200 m2 paddocks) according to a randomised complete block design, with four replications. There was a seasonal pattern of variation in the morphogenetic responses and in herbage utilisation efficiency (HUE) characterised by higher herbage growth rates and HUE during late spring and summer. Nitrogen fertilisation increased both leaf appearance and elongation rates (around 60 % between non-fertilised and swards fertilised with 450 kg ha–1, p < 0.05), requiring higher stocking rates (average of 1.6, 2.6, 2.9 and 3.1 Animal Unit (adult animal weighing 450 kg) ha–1 for 0...

Morphogenetic and structural characteristics of andropogon grass submitted to different cutting heights

Sousa,Braulio Maia de Lana; Nascimento Júnior,Domicio do; Silva,Sila Carneiro da; Monteiro,Hélida Christhine de Freitas; Rodrigues,Carlindo Santos; Fonseca,Dilermando Miranda da; Silveira,Márcia Cristina Teixeira da; Sbrissia,André Fischer
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2010 EN
Relevância na Pesquisa
26.44%
This work was performed aiming to evaluate the morphogenetic and structural characteristics of Andropogon gayanus cv. Planaltina species submitted to three cutting heights (20, 27 and 34 cm). The three cutting heights were allocated in experimental units (12 m²) in a complete randomized block design with three replications. The cuts were done when the light interception by the sward reached 95%. At this moment, the sward height revealed itself constant with values close to 50 cm. The lowest cutting height (20 cm) influenced negatively the final leaf blade length, the number of live leaves, the leaf lifespan, the stem elongation rate and the tiller population density, and it influenced positively the phyllochron and the leaf senescence rate. Probably, cuts at 20 cm height caused a high decapitation and death of the tillers. The worst growth conditions in addition to the blossom of this specie occurred during fall resulted in higher stem elongation rates and number of live leaves, and lower phyllochron, final leaf blade length, and leaf lifespan. The sward height can be used as a practical and efficient criterion in the management of andropogon grass. Under intermittent management conditions, the regrowth of andropogon grass must be interrupted when the sward reaches 50 cm height...

Structural and morphogenical characteristics of black oats and Italian ryegrass on pasture submitted to two grazing intensities

Confortin,Anna Carolina Cerato; Rocha,Marta Gomes da; Quadros,Fernando Luiz Ferreira de; Glienke,Carine Lisete; Rossi,Guilherme Ebling; Moraes,Andréia Barros de
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2010 EN
Relevância na Pesquisa
36.16%
Morphogenical and structural characteristics of black oats (Avena strigosa Schreb.) and Italian ryegrass (Lolium multiflorum Lam.) on pastures managed under two grazing intensities were quantified by using marked tiller technique. The expected intensities of disappearance of forage mass initial value were 35% (low) and 65% (high). Experimental animals were sheep and interval among grazing was determined through 300 degree-day thermal sum. The experimental design was completely randomized with two grazing intensities and two replicates. Leaf blades of oats and ryegrass were removed at an average proportion of 57.5% of their initial length for both grazing intensities. Among the morphogenical characteristics of oats, only elongation rate of defoliate leaf differed between grazing intensities, with values of 0.059 and 0.081 cm/degree-day for low and high intensities, respectively. Grazing intensities did not alter structural characteristics of oats mixed with ryegrass and red clover. High grazing intensity enables maintenance of a higher number of ryegrass expanding leaves (1.7 leaves/tiller), thus it is suggested for management of pastures with oats mixed with Italian ryegrass and red-clover on intermittent grazing.

Morphogenesis of dwarf elephant grass clones in response to intensity and frequency of defoliation in dry and rainy seasons

Gomide,Carlos Augusto de Miranda; Paciullo,Domingos Sávio Campos; Costa,Igor de Almeida; Lima,Aline Medeiros; Castro,Carlos Renato Tavares de; Lédo,Francisco José da Silva
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2011 EN
Relevância na Pesquisa
36.32%
The aim of this study was to evaluate during the dry and rainy seasons the morphogenesis traits of two clones of dwarf elephant grass under different management strategies. The study was conducted in a factorial 2 × 2 × 3 design, using two clones, one green and one purple, two residual heights, 25 and 45 cm, and three frequencies of defoliation according to the light interception of 90, 95 and 100%. The design was a randomized block with three replications. The variables were leaf elongation and leaf senescence rate, stem elongation rate and phyllochron. The leaf lifespan and the number of living leaves per tiller were also estimated. The clones presented low stem elongation rates, showing adaptation for grazing use. In the rainy season, the light interception of 100% promoted the highest stem elongation rate and increased the leaf senescence rate. In the dry season, the leaf elongation rate (LER) was higher for the purple clone than for the green one (23 vs 15 mm.tiller-1.day-1). In the rainy season, the LER of the green clone exceeded that of the purple one by 71% (149 vs. 87 mm.tiller-1.day-1). The phyllochron varied among clones only in the rainy season, when the value was 4.6 days.leaf-1 for the green clone and 8.4 days.leaf-1 for the purple one; both of these values are below the mean value observed during the drought (21...

Morphogenesis of native grasses of Pampa Biome under nitrogen fertilization

Machado,Juliana Medianeira; Rocha,Marta Gomes da; Quadros,Fernando Luiz Ferreira de; Confortin,Anna Carolina Cerato; Santos,Aline Bosak dos; Sichonany,Maria José de Oliveira; Ribeiro,Laila Arruda; Rosa,Aline Tatiane Nunes da
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
46.48%
Morphogenetic and structural characteristics of the native grasses of the Pampa Biome Andropogon lateralis, Aristida laevis, Axonopus affinis, Erianthus angustifolius, Paspalum notatum, Paspalum plicatulum, Piptochaetium montevidense and Sorghastrum pellitum were evaluated as to the effect of nitrogen (N) fertilization (zero and 100 kg N/ha). The experimental design was of randomized blocks with three replicates in a 8 × 2 (native grasses × N) factorial arrangement. Accumulated thermal sums of 350 and 700 degree days determined the interval between cuts for prostrate and caespitose growth habit species, respectively. Species considered of resource conservation (A. laevis, E. angustifolius, P. plicatulum and S. pellitum) had the highest leaf elongation rate when they received N. For leaf appearance rate, phyllochron, leaf senescence rate, leaf lifespan, number of green leaves and final length of leaf blades, there was difference between the evaluated species.

Foliar growth of Eriocnema fulva Naudin (Melastomataceae) in a forest fragment in southeastern Brazil

Andrade,PM.; Santos,FAM.; Martins,FR.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2008 EN
Relevância na Pesquisa
36.32%
Eriocnema fulva Naudin is an endangered herbaceous, perennial, iteroparous, evergreen species geographically restricted to southeastern-center Minas Gerais State, SE Brazil. The individuals occur as patches on rocky riverbanks shaded by seasonal semideciduous Atlantic forest; they are fixed by roots and have a pending stem. Aiming to investigate leaf development and its importance for individual survival, fifteen contiguous plots (1 x 1 m) were set down in Jambreiro Forest (19° 58’-59’ S and 43° 52’-55’ W, 800-1100 m altitude), in the municipality of Nova Lima. A total of 260 individuals with the largest leaf blade length > 1 cm was tagged and measured in 1997, 1998, and 1999. Leaf expansion was recorded each month during 26 months until April 2000. Plant size was measured through leaf blade length, petiole length, stem length, and number of leaves. Significant changes were detected only after two years, thus indicating that plant growth is slow. The proportion of surviving leaves after two years was 60%. Total blade expansion took over 14 months, a slow growth rate when compared to leaves of other tropical forest canopy and understory species. Long leaf lifespans are to be found in plants exhibiting slow growth, and we observed that some leaves lived longer than three years. Petiole growth can help to better position the leaf in the search for light...

Seasonal variation in the maximum rate of leaf gas exchange of canopy and understory tree species in an Amazonian semi-deciduous forest

Sendall,Kerrie M.; Vourlitis,George L.; Lobo,Francisco A.
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
36.34%
Leaf gas exchange, water potential, and specific leaf area of two tropical semi-deciduous tree species, Brosimum lactescens S. Moore and Tovomita schomburgkii Planch & Triana, were quantified to establish how these properties were affected by seasonal variations in rainfall and leaf canopy position. The study was conducted at a site near Sinop Mato Grosso, Brazil, which is located within the ecotone of savanna and tropical rain forest. Both species exhibited significant declines in leaf water potential (ΨL), specific leaf area, area- and mass-based light saturated photosynthesis and dark respiration, and maximum stomatal conductance during the dry-season, suggesting that leaf structural properties and gas exchange are significantly altered by drought that develops during the 4-month dry season. Internal leaf CO2 concentrations (Ci) were consistently lower during the dry season suggesting that the decline in maximum photosynthesis was due in part to a decline in stomatal conductance. However, seasonal variations in leaf gas exchange were larger for upper-canopy leaves, indicating an important interaction between drought stress and canopy position. The seasonal variation in leaf gas exchange and morphology was presumably due to a combination of drought stress and leaf lifespan. The results of this study suggest that drought has important implications for the leaf physiology and morphology of semi-deciduous Amazonian forest trees.

Leaf lifetime photosynthetic rate and leaf demography in whole plants of Ipomoea pes-caprae growing with a low supply of calcium, a ‘non-mobile’ nutrient

Suárez, N.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.7%
The adaptive significance of leaf longevity has been established in relation to restrictive nutrients that can be retranslocated within the plant. However, the effect of deficiencies in ‘non-mobile’ nutrients on leaf lifespan and photosynthetic carbon gain is uncertain. Calcium is frequently given as an example of an essential nutrient with low phloem mobility that may alter the leaf senescence process. This study has been designed to estimate leaf lifespan, leaf production (Lp) and leaf death (Ld) rates, the age structure of leaves, and the decline in maximum photosynthetic rate (Amax) with age in plants of Ipomoea pes-caprae growing with a full supply of nutrients and with a low Ca supply. The Ca deficiency produced reductions in Lp and leaf lifespan compared with control plants. In spite of the differences in the demographic parameters between treatments in control and low-Ca plants, the percentage of leaves of a given leaf age class is maintained in such a way that the number of leaves per plant continues to increase. No relationship was found between Ca supply and Amax. However, the decline in Amax with leaf senescence was rather sudden in control plants compared with plants growing with a low Ca supply. The importance of simultaneously using the total leaf demographic census and the assimilation rate along with leaf lifespan data in order to understand the performance of whole plants under constrained conditions is discussed.

Manejo da desfolha na ecofisiologia da produ????o de forragem e sementes de azev??m anual; Management of defoliation in ecophysiology of forage production and annual ryegrass

CUNHA, Ricardo Pereira da
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
Relevância na Pesquisa
26.44%
Annual ryegrass production of (Lolium multiflorum Lam) in Rio Grande do Sul is usually obtained from pasture areas and subsequently deferred pasture. Understanding the physiological ecology of annual ryegrass plant is essential for proper management program, with objective of getting higher forage production and seed. Therefore, the effects of different frequencies of defoliation were measured at (zero, one, two and three) on morphogenesis characteristics of annual ryegrass plants, cultivar BRS Ponteio‟. The following characteristics were evaluated (rate of leaf appearance, phyllochron, leaf expansion rate, rate of leaf senescence, rate of stem expansion, tillering rate and leaf lifespan), forage and seed, and the seed yield components (number of tillers per plant, number of fertile tillers per plant, length of tillers, length of spike, number of spikelets per spike, number of seeds per spikelet and total seed production). The plant behavior was assessed for seven months from (04/29/11 to 11/18/11). Defoliation affected the morphogenesis characteristics, amount of forage and seed harvested of ryegrass cultivar BRS Ponteio‟. The implementation of the second defoliation increased more than 100% the amount of harvested forage in relation to only one defoliation management and without reducing seed yield. The third defoliation contributed significantly to the total harvested forage...

Parasites boost productivity: Effects of mistletoe on litterfall dynamics in a temperate Australian forest

March, W.; Watson, D.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
36.21%
The importance of litter in regulating ecosystem processes has long been recognised, with a growing appreciation of the differential contribution of various functional plant groups. Despite the ubiquity of mistletoes in terrestrial ecosystems and their prominence in ecological studies, they are one group that have been overlooked in litter research. This study evaluated the litter contribution from a hemiparasitic mistletoe, Amyema miquelii (Lehm. ex Miq.) Tiegh., in an open eucalypt forest (Eucalyptus blakelyi, E. dwyeri and E. dealbata), at three scales; the forest stand, single trees and individual mistletoes. Litter from mistletoes significantly increased overall litterfall by up to 189%, the amount of mistletoe litter being proportional to the mistletoe biomass in the canopy. The high litter input was due to a much higher rate of mistletoe leaf turnover than that of host trees; the host litterfall and rate of leaf turnover was not significantly affected by mistletoe presence. The additional litter from mistletoes also affected the spatial and temporal distribution of litterfall due to the patchy distribution of mistletoes and their prolonged period of high litterfall. Associated with these changes in litterfall was an increase in ground litter mass and plant productivity...

Freqüência e severidade de desfolhação e eficiência de utilização de forragem em pastos de capim-marandu manejados sob lotação contínua e ritmos de crescimento induzidos por fertilização nitrogenada; Frequency and severity of defoliation and utilisation efficiency on marandu palisadegrass subjected to continuous stocking and nitrogen-induced rhythms of growth

Guarda, Vitor Del'Alamo
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 24/06/2010 PT
Relevância na Pesquisa
26.69%
Modificações no ritmo de crescimento de plantas forrageiras podem ter implicações nos processos de acúmulo de forragem e colheita da forragem produzida. Desse modo, a adequação de estratégias de manejo que proporcionem melhor eficiência, tanto no processo de crescimento como de utilização são objetivos de um sistema de produção ideal. Nesse contexto, o objetivo deste trabalho foi avaliar a freqüência e severidade de desfolhação de perfilhos e folhas e quantificar a eficiência de utilização da forragem produzida em pastos de capim-marandu manejados a 30 cm sob lotação contínua e submetidos a ritmos de crescimento gerados pela aplicação das doses de nitrogênio 150, 300 e 450 kg/ha.ano, mais o controle (sem adubação). Os tratamentos foram alocados às unidades experimentais (piquetes de 1200 m2) segundo um delineamento de blocos completos casualizados, com quatro repetições. Foram coletados dados de 30 perfilhos por piquete em ciclos de 28 dias. Após 28 dias, novos perfilhos eram selecionados e um novo ciclo de avaliações realizado. Foram avaliadas as seguintes variáveis-resposta de janeiro de 2007 a abril de 2008: densidade de lotação animal, freqüência de desfolhação de perfilhos, freqüência de desfolhação de folhas...

Functional relationships between leaf hydraulics and leaf economics in response to nutrient addition in subtropical tree species

Villagra, Mariana; Campanello, Paula Inés; Bucci, Sandra Janet; Goldstein, Guillermo Hernan
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
56.67%
Leaves can be both a hydraulic bottleneck and a safety valve against hydraulic catastrophic dysfunctions, and thus changes in traits related to water movement in leaves and associated costs may be critical for the success of plant growth. A 4-year fertilization experiment with nitrogen (N) and phosphorus (P) addition was done in a semideciduous Atlantic forest in northeastern Argentina. Saplings of five dominant canopy species were grown in similar gaps inside the forests (five control and five N + P addition plots). Leaf lifespan (LL), leaf mass per unit area (LMA), leaf and stem vulnerability to cavitation, leaf hydraulic conductance (K(leaf_area) and K(leaf_mass)) and leaf turgor loss point (TLP) were measured in the five species and in both treatments. Leaf lifespan tended to decrease with the addition of fertilizers, and LMA was significantly higher in plants with nutrient addition compared with individuals in control plots. The vulnerability to cavitation of leaves (P50(leaf)) either increased or decreased with the nutrient treatment depending on the species, but the average P50(leaf) did not change with nutrient addition. The P50(leaf) decreased linearly with increasing LMA and LL across species and treatments. These trade-offs have an important functional significance because more expensive (higher LMA) and less vulnerable leaves (lower P50(leaf)) are retained for a longer period of time. Osmotic potentials at TLP and at full turgor became more negative with decreasing P50(leaf) regardless of nutrient treatment. The K(leaf) on a mass basis was negatively correlated with LMA and LL...

Irradiance, temperature and rainfall influence leaf dark respiration in woody plants: evidence from comparisons across 20 sites

Wright, Ian J; Reich, Peter B; Atkin, Owen; Lusk, Christopher H.; Tjoelker, Mark G; Westoby, Mark
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.29%
• Leaf dark respiration (R) is one of the most fundamental physiological processes in plants and is a major component of terrestrial CO2 input to the atmosphere. Still, it is unclear how predictably species vary in R along broad climate gradients. • D

Leaf-trait variation explained by the hypothesis that plants maximize their canopy carbon export over the lifespan of leaves

McMurtrie, Ross; Dewar, Roderick
Fonte: Heron Publishing Publicador: Heron Publishing
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.44%
Measured values of four key leaf traits (leaf area per unit mass, nitrogen concentration, photosynthetic capacity, leaf lifespan) co-vary consistently within and among diverse biomes, suggesting convergent evolution across species. The same leaf traits co

Herbage utilisation efficiency of continuously stocked marandu palisade grass subjected to nitrogen fertilisation

Pereira, Lilian Elgalise Techio; Paiva, Adenilson José; Guarda, Vitor Del’Álamo; Pereira, Priscila de Mesquita; Caminha, Fábio Olegário; Silva, Sila Carneiro da
Fonte: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz Publicador: Universidade de São Paulo. Escola Superior de Agricultura Luiz de Queiroz
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; Formato: application/pdf
Publicado em 01/02/2015 ENG
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Nitrogen fertiliser accelerates plant growth and increases herbage utilisation efficiency in continuously stocked temperate grass swards, indicating greater herbage production and harvest efficiency. There is no similar evidence, however, for tropical pastures. In this study we evaluated the morphogenetic responses, the patterns of defoliation and the efficiency of herbage utilisation of continuously stocked marandu palisade grass (Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. Marandu) maintained at 30 cm by cattle and fertilised with nitrogen. Treatments corresponded to four measures of nitrogen application (0, 150, 300 and 450 kg ha–1), and were assigned to experimental units (1,200 m2 paddocks) according to a randomised complete block design, with four replications. There was a seasonal pattern of variation in the morphogenetic responses and in herbage utilisation efficiency (HUE) characterised by higher herbage growth rates and HUE during late spring and summer. Nitrogen fertilisation increased both leaf appearance and elongation rates (around 60 % between non-fertilised and swards fertilised with 450 kg ha–1, p < 0.05), requiring higher stocking rates (average of 1.6, 2.6, 2.9 and 3.1 Animal Unit (adult animal weighing 450 kg) ha–1 for 0...