South Texas Cabrito Recipes.

20 p

Estimating of actual vineyard evapotranspiration using the multilayer models

120 p.En estos días el agua se ha convertido en un recurso clave para la sustentavilidad de la agricultura debido a su disminución por efecto del uso indiscriminado de este recurso y el cambio climático. En Chile a la disminución hídrica se suman cambios en la intensidad y frecuencia de anomalías climáticas “El Niño” y “La Niña” (oscilación ENOS). Una forma de enfrentar esta problemática a nivel agrícola consiste en mejorar las técnicas de programación del riego, para realizar un uso más racional del recurso hídrico. Para obtener una programación de riego óptima es necesaria una buena aproximación a las necesidades hídricas reales de las plantas, es decir la evapotranspiración actual (ETa). Tradicionalmente, la evapotranspiración actual es obtenida por medio de la evapotranspiración de referencia (ETo) y los coeficientes de cultivo (Kc) (FAO-56). Sin embrago, el principal problema de esta metodología es que los coeficientes de cultivos obtenidos de literatura no están adaptados a las condiciones locales. Otro problema, relacionado a esta metodología es que en Chile muchas de las estaciones automáticas están instadas en el propio viñedo, lo cual no corresponde a una superpie en condiciones de referencia. En este contexto los modelos multicapa (dos y tres capas) son una alternativa para estimar directamente ETa en el viñedo, sin utilizar coeficientes de cultivo. Para la cuantificación de ETa en viñedos es necesario considerar la existencia de una cubierta es estratificada debido a la estructura impuesta por los sistemas de conducción, por lo se plantea el uso de modelos tipo multi-capa que consideran 2 o más superficies evaporantes para la estimación de ETa. La presente tesis aborda la problemática de la estimación de la ETa en un viñedo comercial regado por goteo y conducido en espaldera vertical simple bajo condiciones de manejo convencionales por medio de dos modelos de simulación multicapa (1) Modelo de Shuttleworth y Wallace SW (Capitulo 2) y Modelo de Brenner y Incoll 1997 Clumped (Capitulo 3). Finalmente, cabe destacar que gracias a los avances en el modelamiento matemático e instrumentación meteorológica, es posible proyectar una clara posibilidad para estimar el consumo de agua (ETa) de forma práctica permitiendo gestionar de mejor forma el recurso hídrico potenciales escenarios de cambio climático y escasez hídrica. Palabras claves: Viñedo, evapotranspiración actual, escasez hídrica, cambio climático, modelos multicapa./ ABSTRACT: These days water has turned into a key resource for sustainable agriculture due to the fact it is decreasing because of its indiscriminate use and climatic change. In Chile water scarcity is aggravated by the increase of the intensity and frequency of climatic anomalies (oscillation ENSO). A way to deal with this problem at the agricultural level is to improbé irrigation scheduling, with the objective of providing a more rational use of the water resource. To obtain optimal irrigation scheduling it is necessary to have a good approach to the water consumption of plants, i.e. actual evapotranspiración (ETa). Traditionally, values of ETa have been calculated using a reference evapotranspiration (ETo) and crop coefficients (Kc) (FAO- 56). However, the main problem of this method is that the crop coefficients reported in literature are not adapted to the local conditions. Another problem is that in Chile many automatic weather stations are installed within vineyards where vine canopies do not correspond to a surface in the reference conditions. In this context the multilayer models (two and three layer) are a real alternative to directly estimate ETa in vineyards, without Kc values. To estimate ETa in vineyards it is necessary to consider the existence of a partial covering due to the structure imposed by the trellis systems; for this reason we considered the use of multilayer models that consider 2 or more evaporative surfaces to estimate ETa. The present thesis considers the problem of estimating ETa in a commercial vineyard, drip irrigated and trained on a vertical shoot positioned system (VSP) under conventional agronomic Management practices by means of two multilayer models: (1) Shuttleworth and Wallace (SW) two-layer model (Chapter 2), and Brenner and Incoll 1997 (Clumped) three-layer model (Chapter 3). Finally, it is necessary to emphasize that the advances in mathematical modeling and meteorological instrumentation, provide the opportunity to project a clear estimation of water consumption (ETa) in a practical form, allowing better management of the water resource considering potential stages of climatic change and water scarcity. Keywords: Vineyard, actual evapotranspiration, water scarcity, climatic change, multilayer models, spatial variabilit

Effects of Water Deficits on Prosopis tamarugo Growth, Water Status and Stomata Functioning

The effect of water deficit on growth, water status and stomatal functioning of Prosopis tamarugo was investigated under controlled water conditions. The study was done at the Antumapu Experiment Station of the University of Chile. Three levels of water stress were tested: (i) well-watered (WW), (ii) medium stress intensity (low-watered (LW)) and (iii) intense stress (non-watered (NW)), with 10 replicates each level. All growth parameters evaluated, such as twig growth, specific leaf area and apical dominance index, were significantly decreased under water deficit. Tamarugo twig growth decreased along with twig water potential. The stomatal conductance and CO2 assimilation decreased significantly under the water deficit condition. Tamarugo maintained a high stomatal conductance at low leaf water potential. In addition, tamarugo reduced its leaf area as a strategy to diminish the water demand. These results suggest that, despite a significant decrease in water status, tamarugo can maintain its growth at low leaf water potential and can tolerate intense water deficit due to a partial stomatal closing strategy that allows the sustaining of CO2 assimilation in the condition of reduced water availability

Anatomía del tejido fotosintético de diez taxa de Opuntia establecidos en el secano árido mediterráneo de Chile Anatomy of the photosynthetic tissue in ten taxa of Opuntia established to the mediterranean arid zone of Chile

Se evaluó el efecto de la exposición de cladodios a la radiación en la anatomía del tejido fotosintético de 10 taxa de Opuntia, (plantas con metabolismo ácido crasuláceo, CAM) establecidos en al secano árido de la IV Región de Chile. A nivel del tejido epidérmico se evaluó el grosor de la cutícula, la densidad de estomas y las dimensiones de células oclusivas. En el tejido fotosintetico, se evaluo las dimensiones celulares con el objeto de estimar la superficie de paredes celulares expuestas al intercambio gaseoso por unidad de tejido fotosintético, relación conocida como Ames/A. Los resultados señalan grandes dimensiones celulares y baja densidad estomática, lo que determina un número reducido de estomas por unidad de superficie en relación a especies de otras vías metabólicas (C3 y C4). La comparación entre taxones, muestra diferencias significativas en la relación de áreas Ames/A, parámetro estrechamente relacionado a la capacidad fotosintética. Estas características anatómicas y sus modificaciones en combinación con el metabolismo CAM, contribuyen a su adaptación a condiciones de pluviometría limitadaThe anatomy of the photosynthetic tissue and the effect of cladode exposure to radiation was studied in ten taxa of Opuntia, plants with crassulacean acid metabolism (CAM), established in the dry lands of the IV Region of Chile. At the epidermic level the cuticle thickness, stomatal frequency, and dimension of guard cells were evaluated. In the photosynthetic tissue, cell dimensions were determined in order to estimate the area of cell walls exposed to gaseous exchange per unit of photosynthetic tissue (A mes/ A). The results indicate large cell dimensions and low stomata frequency which results in a reduced number of stomata per unit area in relation to species with other metabolic pathways (C3 and C4), The comparison between taxa shows significant differences in the relation of Ames/A areas, a parameter closely associated to the photosynthetic capacity and water use efficiency. The above anatomic characteristics of these plants in combination with pathway CAM contribute to their adaptation to limited rainfall condition

Agronomía de la cero labranza

El extracto expone algunas observaciones al agricultor que recién se inicia en este sistema, y muestra los efectos que éste produce en las propiedades del suelo; posteriormente revisa el tema de rastrojos, incluyendo el manejo y sus efectos aleopáticos. También da una reseña a la maquinaria a utilizarse, la fertilización, y control de malezas, terminándose en un breve resumen, y algunas consideraciones económicas.FIA. Proyecto FIA-PR-V-2002-1A-026 FONDEF. Proyecto D99I1081 DID 2002-I-0215-

Evaluation for fresh consumption of new broad bean genotypes with a determinate growth habit in central Chile

Broad bean (Vicia faba L. [unranked] major (Harz) Beck) is usually consumed dry. In Chile, however, broad bean is grown as a vegetable crop with indeterminate genotypes. The new 'Alarga', 'Retaca' and 'Verde Bonita' broad bean genotypes, which have a determinate growth habit, were evaluated in six irrigated environments in central Chile at three locations (Rancagua, Talca, and Talagante) and on two planting dates (F1 and F2; 1-mo apart). The aim was to characterize their yield and select the best-yielding genotypes in terms of pod yield (PY) and fresh grain yield (GY). The best location(s) to produce fresh pods and fresh grain were also identified and described. Fresh grain yield and components were measured and the genotype x environment interaction (GxE) was analyzed. Pod yield differed among genotypes; 'Verde Bonita' and 'Retaca' had the highest PY (15 500 kg ha-1, 8% higher than 'Alarga'). There was a GxE interaction for GY and 'Retaca' had its highest yield in Talca on the two planting dates and in Rancagua when planted late (F2). Mean GY of 'Retaca' was 3900 kg ha-1 with the highest number of grains per 1 m² (NG). The best GY was related to a higher seasonal photothermal quotient (ranging from 1.15 to 1.82 MJ m-2 d-1 °C-1, r = 0.90, P d" 0.001). The lowest GY was in Talagante on F1. Genotypes differed in yield composition; 'Retaca' had many small pods giving many seeds per unit area and 'Verde Bonita' had large pods yielding fewer grains per unit area. The 'Retaca' genotype is preferred by the frozen broad bean industry, whereas 'Verde Bonita' is preferred by the fresh broad bean market