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Modelo Simple de Simulación Para la Estimación Del Crecimiento, Fenología y Balance H?drico de Praderas Anuales de Clima Mediterráneo
Castellaro G,Giorgio?; Squella N,Fernando?;
Agricultura Técnica , 2006, DOI: 10.4067/S0365-28072006000300006
Abstract: this work had as objective to elaborate a simple model of pasture growth, phenology and water balance of annual pastures of mediterranean climate. the water balance is performerd only in one soil stratum (40 cm), where it is supposed the root mass is concentrated. it was considered rainfall and the water losses by evapotranspiration, which was calculated as a function of the potential evapotranspiration, the relative water supply level of the soil and the degree of pasture cover. the model supposes an adequate contribution of nutrients, being climatic variables, availability of photosynthetic material and soil water the main limiting for the grassland growth. validation was performed with dry matter accumulation and soil water data measured in mediterranean grassland at the hidango experimental center, belonging to the agricultural research institute (inia) (34o06' s lat ; 71o47' w long; 296 m.o.s.l.) during the season 1992. the results of the validation indicated that this model explained over 90% of the variation of the observed values of dry matter accumulation and soil water. some lines of the model development are proposed, such as the incorporation of subroutines that simulate the nutritive value and the effect of n and shrub stratum, on grassland growth.
Modelo Simple de Simulación Para la Estimación Del Crecimiento, Fenología y Balance H drico de Praderas Anuales de Clima Mediterráneo A Simple Simulation Model to Estimate Pasture Growth, Phenology and Water Balance of Annual Pastures of Mediterranean Climate
Giorgio Castellaro G,Fernando Squella N
Agricultura Técnica , 2006,
Abstract: Este trabajo tuvo como objetivo elaborar un modelo simple del crecimiento, fenología y balance hídrico de praderas anuales de clima mediterráneo. El balance hídrico se realizó en un estrato de suelo (40 cm) donde se concentra la masa radicular. Se consideran los aportes de la precipitación y las pérdidas de agua por evapotranspiración, la que se calculó en función de la evapotranspiración potencial, del nivel relativo de agua y el grado de cobertura de la pradera. El modelo supone un adecuado aporte de nutrimentos, siendo las variables climáticas, la disponibilidad de material fotosintético y la humedad del suelo, las principales limitantes para el crecimiento. La validación fue realizada con datos de acumulación de fitomasa aérea y humedad del suelo, medidas en praderas de clima mediterráneo del Centro Experimental Hidango, perteneciente al Instituto de Investigaciones Agropecuarias (INIA) (34o06’ lat. Sur, 71o47’ long. Oeste, 296 m.s.n.m.) durante la temporada 1992. Los resultados indican que el modelo explicó sobre el 90% de la variación de los valores observados en la acumulación de MS y la humedad del suelo. Se plantean algunas líneas de desarrollo del modelo, como la incorporación de subrutinas que simulen el valor nutritivo, el efecto del N y el del estrato arbustivo, sobre el crecimiento de la pradera. This work had as objective to elaborate a simple model of pasture growth, phenology and water balance of annual pastures of Mediterranean climate. The water balance is performerd only in one soil stratum (40 cm), where it is supposed the root mass is concentrated. It was considered rainfall and the water losses by evapotranspiration, which was calculated as a function of the potential evapotranspiration, the relative water supply level of the soil and the degree of pasture cover. The model supposes an adequate contribution of nutrients, being climatic variables, availability of photosynthetic material and soil water the main limiting for the grassland growth. Validation was performed with dry matter accumulation and soil water data measured in Mediterranean grassland at the Hidango Experimental Center, belonging to the Agricultural Research Institute (INIA) (34o06' S lat ; 71o47' W long; 296 m.o.s.l.) during the season 1992. The results of the validation indicated that this model explained over 90% of the variation of the observed values of dry matter accumulation and soil water. Some lines of the model development are proposed, such as the incorporation of subroutines that simulate the nutritive value and the effect of N and shrub stratum, on gra
Simulation of Dry Matter Productivity and Water Dynamics in a Chilean Patagonian Range
Castellaro G,Giorgio; Morales S,Luis; Ahumada,Mario; Barozzi,Azelio;
Chilean journal of agricultural research , 2010, DOI: 10.4067/S0718-58392010000300009
Abstract: this paper describes a simulation model combining the main components of water balance and growth of perennial grassland steppe in chilean patagonia, to estimate long-term annual production (yr, kg ha-1) and sheep carrying capacity (gc, sheep equivalent [eo] ha-1). the model is based on climate-water balance relationships, where the basic process is evapotranspiration. the model calculates yr depending on the accumulation of transpiration and the water use efficiency from the time of growth initiation until the grassland accumulates the maximum amount of dry matter (dm). depending on yr, the dm requirement of eo, the proper use factor of grassland and a slope correction factor, a range site gc is calculated. simulations were performed using actual climate data sets of eight growing seasons at kampenaike (52o41' s; 70°54'w; 12 m.a.s.l.) and a long-term simulation in the same location, using a stochastic weather variables generator. through the model it was possible to estimate the water loss associated with the components of water balance and estimate the restriction imposed by water deficit on yr. by simulating many years, it was possible to establish a normal distribution of gc with 0.629 eo ha-1 yr-1, associated with 80% probability of being exceeded, which is lower than values reported in field assessments. this method calculates gc with a conservational approach, taking into account soil and climatic variability in semiarid ecosystems.
Simulation of Dry Matter Productivity and Water Dynamics in a Chilean Patagonian Range Simulación de la Productividad de Materia Seca y Dinámica del Agua en Praderas de la Patagonia Chilena
Giorgio Castellaro G,Luis Morales S,Mario Ahumada,Azelio Barozzi
Chilean Journal of Agricultural Research , 2010,
Abstract: This paper describes a simulation model combining the main components of water balance and growth of perennial grassland steppe in Chilean Patagonia, to estimate long-term annual production (Yr, kg ha-1) and sheep carrying capacity (GC, sheep equivalent [EO] ha-1). The model is based on climate-water balance relationships, where the basic process is evapotranspiration. The model calculates Yr depending on the accumulation of transpiration and the water use efficiency from the time of growth initiation until the grassland accumulates the maximum amount of dry matter (DM). Depending on Yr, the DM requirement of EO, the proper use factor of grassland and a slope correction factor, a range site GC is calculated. Simulations were performed using actual climate data sets of eight growing seasons at Kampenaike (52o41' S; 70°54'W; 12 m.a.s.l.) and a long-term simulation in the same location, using a stochastic weather variables generator. Through the model it was possible to estimate the water loss associated with the components of water balance and estimate the restriction imposed by water deficit on Yr. By simulating many years, it was possible to establish a normal distribution of GC with 0.629 EO ha-1 yr-1, associated with 80% probability of being exceeded, which is lower than values reported in field assessments. This method calculates GC with a conservational approach, taking into account soil and climatic variability in semiarid ecosystems. Se describe un modelo de simulación para pastizales esteparios de la Patagonia chilena, que estima a largo plazo los principales componentes del balance hídrico, la producción anual de MS (Yr, kg ha-1) y la capacidad de carga ovina (GC, equivalente ovino [EO] ha-1) de éstos. El modelo se basa en la relación clima-balance hídrico, siendo el proceso básico la evapotranspiración. Yr es función de la acumulación de transpiración durante la temporada de crecimiento y de la eficiencia del uso del agua. La GC del pastizal se calcula en función de Yr, del requerimiento de MS del EO, del factor de uso apropiado de la pradera y de un factor de corrección por pendiente. Se efectuaron simulaciones utilizando datos climáticos reales de ocho temporadas en la localidad de Kampenaike (52o41’ S; 70o54’ O; 12 m s.n.m) y una simulación en el largo plazo para l misma localidad, utilizando un generador estocástico de variables climatológicas. Se cuantificaron las pérdidas de agua asociadas a los componentes del balance hídrico y se estimó el efecto del déficit hídrico sobre Yr. Al simular muchos a os fue posible establecer una función de
EL CONCEPTO DE REPRESENTACIóN MENTAL COMO FUNDAMENTO EPISTEMOLóGICO DE LA PSICOLOGíA
Mariano Castellaro
Límite , 2011,
Abstract: En el presente trabajo se discute sobre la autonomía y estatus científico de la psicología, frente al avance de disciplinas que teorizan sobre el comportamiento humano desde un nivel neurobiológico y/o basado en la inteligencia artificial. Se propone el concepto de representación mental como el objeto propio de la ciencia psicológica, lo cual le otorga un estatus epistemológico y delimita un ámbito disciplinar específico. Inicialmente, se efectúa un repaso de diferentes perspectivas acerca del concepto, para luego plantear la hipótesis central del artículo propuesta con anterioridad. Finalmente, se analiza el aporte del constructivismo con respecto al concepto y su crítica al modelo tradicional basado en el realismo. El objetivo último del trabajo es mostrar la posibilidad de complementación entre la psicología y las neurociencias, manteniendo cada una su nivel de análisis específico.
Un Modelo de Simulación de Sistemas de Engorda de Bovinos a Pastoreo
Castellaro G,Giorgio; Klee G,Germán; Chavarría R,Jorge;
Agricultura Técnica , 2007, DOI: 10.4067/S0365-28072007000200006
Abstract: a simulation model of beef cattle fattening systems based on grazing pastures was developed. the objective was to evaluate different pasture options under different management strategies, types of beef cattle, stocking densities, supplementation strategies and input prices. this model was structured based on a program, whose main module drives management input and generates result files. the dynamic section uses biological subroutines to solve equations simulating biological processes, the most important being the metabolizable energy intake and live weight change. pasture growth and nutritive value were simulated empirically from the interpolation of monthly data of pasture growth and digestibility of different pasture types. the model also calculates processes related to pasture management, forage conservation and bioeconomic aspects. the physical grazing experiment, carried out during the 1979-1980 seasons was utilized to validate the animal sub-system, a coefficient of determination higher than 95% was obtained when simulated and real values measured in the respective experiments were correlated by regression analysis, verifying the non existence of bias in the estimations. the root mean square error (rmse) was smaller than 6%, suggesting that this model is realistic and has a high degree of precision
Un Modelo de Simulación de Sistemas de Engorda de Bovinos a Pastoreo Beef Fattening Simulation Model for Different Grazing Systems
Giorgio Castellaro G,Germán Klee G,Jorge Chavarría R
Agricultura Técnica , 2007,
Abstract: Se elaboró un modelo de simulación de sistemas de producción de carne basado en utilización de pasturas, cuyo objetivo fue evaluar diferentes alternativas pratenses bajo distintas modalidades de manejo, tipos de bovinos, densidades de carga, estrategias de suplementación y precios de insumos. El modelo se estructuró sobre la base de un programa computacional, cuyo módulo principal maneja archivos de datos de manejo y genera archivos de resultados. La sección dinámica está estructurada en subrutinas orientadas a resolver ecuaciones que simulan los procesos biológicos, siendo los más importantes el consumo de energía metabolizable y el cambio de peso vivo. El crecimiento y valor nutritivo de los pastizales fue simulado empíricamente a partir de la interpolación de datos mensuales de tasas de crecimiento y digestibilidad de diferentes tipo de pasturas. El modelo también calcula los procesos relacionados con el manejo del pastoreo, conservación de forrajes y aspectos bioeconómicos. Para la validación del subsistema animal, se utilizaron los datos de peso vivo de toretes Hereford obtenidos de los experimentos físicos de pastoreo realizados durante la temporada 1979-1980. Al relacionar mediante un análisis de regresión los valores simulados con los medidos en los experimentos, se obtuvo un coeficiente de determinación superior al 95%, confirmándose la inexistencia de sesgo en la estimación. La raíz del error cuadrático medio (RMSE) no superó el 6%, lo que indicaría que este modelo es realista y tiene un alto grado de precisión. A simulation model of beef cattle fattening systems based on grazing pastures was developed. The objective was to evaluate different pasture options under different management strategies, types of beef cattle, stocking densities, supplementation strategies and input prices. This model was structured based on a program, whose main module drives management input and generates result files. The dynamic section uses biological subroutines to solve equations simulating biological processes, the most important being the metabolizable energy intake and live weight change. Pasture growth and nutritive value were simulated empirically from the interpolation of monthly data of pasture growth and digestibility of different pasture types. The model also calculates processes related to pasture management, forage conservation and bioeconomic aspects. The physical grazing experiment, carried out during the 1979-1980 seasons was utilized to validate the animal sub-system, A coefficient of determination higher than 95% was obtained when simulated and r
A Simulation Model of Mesophytic Perennial Grasslands Un Modelo de Simulación de Pradera Perenne Mesofítica
Giorgio Castellaro G,Claudio Aguilar G,Raul Vera I,Luis Morales S
Chilean Journal of Agricultural Research , 2012,
Abstract: Grasslands are complex ecosystems and their processes are affected by soil, meteorological, and management variables. In this context, dynamic simulation models are useful to understand these processes and to design grassland use strategies. The aim of this study was to develop and validate a simulation model of perennial pasture growth based on soil and climate variables. A first approach considered that soil fertility levels were adequate; therefore, soil water availability and phytomass level were the main variables affecting pasture growth. The subroutines considered were water balance, pasture growth, and root biomass dynamics. The hypotheses regarding the functioning of the system were formulated as a group of equations which were solved numerically with a program written in Visual Basic . Model validation was performed by statistical comparison between simulated DM and DM obtained from experiments conducted in Valdivia (39°47' S., 73°15' W; 9 m a.s.l.). In these experiments we measured DM accumulation on naturalized grassland and ryegrass (Lolium perenne L.)-white clover (Trifolium repens L.) pastures under frequent defoliation. Soil data, temperature, solar radiation, and rainfall were obtained from a meteorological station located in Valdivia. The coefficient of determination between simulated values and those measured in the experiments were higher in the DM accumulation (R2 = 98%) simulations. When pasture was subjected to frequent defoliation, the degree of fit of the model was lower (R2 = 60%); however, the model was able to predict the trend in the data. Los pastizales son ecosistemas complejos y sus procesos se ven afectados por variables edáficas, meteorológicas y de manejo. En este contexto, los modelos dinámicos de simulación son utiles para la comprensión de estos procesos y disenar estrategias de utilización de las praderas. El objetivo de este trabajo fue elaborar y validar un modelo de simulación de crecimiento de pastizales perennes, basado en variables de suelo y clima. En una primera aproximación se consideró que el suelo tenia adecuados niveles de fertilidad, por lo cual la disponibilidad de agua y el nivel de fitomasa fueron las principales variables que inciden sobre el crecimiento del pastizal. Se consideraron subrutinas de balance hídrico, crecimiento del pastizal y dinámica de biomasa radical. Las hipótesis referidas al funcionamiento del sistema fueron formuladas en un sistema de ecuaciones, el cual se resolvió numéricamente mediante un programa escrito en Visual Basic . La validación del modelo se efectuó a través de la
Composición botánica de la dieta de alpacas (Lama pacos L.) y llamas (Lama glama L.) en dos estaciones del a?o, en praderas altiplánicas de un sector de la Provincia de Parinacota, Chile
Castellaro G.,Giorgio; Ullrich R.,Tamara; Wackwitz,Birgit; Raggi S.,Alberto;
Agricultura Técnica , 2004, DOI: 10.4067/S0365-28072004000400004
Abstract: the botanical composition of alpaca (lama pacos l.) and llama (lama glama l.) diets was determined, grazing on a highland range of parinacota, chile (18°12' s lat; 69°16' w long; 4390 m.o.s.l.), using microhistological analysis of feces. the evaluations were carried out in dry-winter and rainy-summer seasons. the availability of dry matter (ms) and botanical composition (bc) of the main grassland, the "bofedal," was measured. the availability of dm varied between 1860 and 2940 kg ha-1, and the bc was dominated by oxychloe andina (cyperaceae) and festuca nardifolia (poaceae). diets were dominated by species of the bofedal, especially by the grasses (f. nardifolia, deschampsia caespitosa and agrostis tolucensis) and grass-like plants (o. andina), also being prominent, the "pajonal" and "tholar" species, festuca orthophylla and parastrephia lucida, respectively, especially in winter and in llama diets. diets differed in their composition and diversity, there being an interaction between the type of herbivore and the season of the year, with a significant overlapping between 61.4% in summer and 73.6%, in winter, that suggests a differentiated grazing management of these camelids to avoid eventual competition. the ivlev?s selectivity index, highlighted the grass species a. tolucensis, d. caespitosa and the ranunculaceae ranunculus uniflorus, which obtained positive values close to one, indicating a high preference by the herbivores. whereas, the dominant species of bofedal, o. andina, obtained a negative value (rejection), and consequently, tended to dominate in the bc of grassland, having a negative effect on the grassland?s condition.
Algunas Técnicas Microhistolóigcas Utilizadas en la Determinación de la Composición Botánica de Dietas de Herbívoros
Castellaro G,Giorgio?; Squella N,Fernando?; Ullrich R,Tamara? ?; León C,Felipe?; Raggi S,Alberto?;
Agricultura Técnica , 2007, DOI: 10.4067/S0365-28072007000100011
Abstract: this work describes different microhistological techniques, to study wild and domestic herbivore diets. the methods to obtain epidermal tissue were applied to the main vegetal species of the mediterranean and high plain pastures, to evaluate the degree of resolution in their identification and characterization. in most grasses and grass-like species, the epidermal tissue was obtained easily by scraping without complications, identifying species based on specific characteristics of the cellular wall, cell size and shape, presence and shape of cork and silica cells, and presence and shape of trichomes. in some poaceas with very hard epidermis, prior treatment with ether and nitric acid was necessary before scraping. in wood and wide leaf herbaceous species, the diafanization method was the most efficient way to obtain the epidermis, and species identification was based on cell and trichome shape, and in some cases, on stomas shape, but, in some genera, species differentiation was not possible. the microhistological technique proved to be a useful tool to obtain epidermis of plant species, being an accurate method to identify and characterize this structure. some wide leaf herbaceous species showed a strong sensitivity to diafanization, so this technique should be developed.
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