Influencia de portainjertos sobre el contenido peciolar de nitrógeno, fósforo y potasio en cuatro variedades de uva de mesa

Four field trials were conducted at Vicuña Experimental Center (30°02' S, 70°44' W) located in the Coquimbo Region, Chile, over four seasons, 2002-2003 to 2005-2006, to determine the influence of 10 rootstocks (Freedom, Harmony, Saint George, Salt Creek, SO4, 1613C, 1103P, 99R, 110R, 140Ru, as well as own roots vines) on nutrient content in petioles of vars. Flame Seedless, Thompson Seedless, Superior Seedless and Red Globe grapevines ( Vitis vinifera L.). The trials took place at a site that had previously planted to vineyard. The experimental design was a randomized complete block with four replicates. Petioles opposite to clusters were taken at bloom as samples and analyzed for total N, P and K content. Significant differences in nutrient levels due to rootstocks were found in all varieties. Rootstocks increased the levels of petiole nutrients (except P) over the values usually reported in literature for table grapes. Vines grafted onto the rootstock 'Salt Creek' had significantly higher petiole N and P content than those on their own roots vines. Total N level increased 67% in 'Flame Seedless', 77% in 'Red Globe', 33% in 'Thompson Seedless' and 8.5% in 'Superior Seedless'. On the other hand, the petiole P level doubled in all varieties by using 'Salt Creek' as rootstock. Potassium status was also affected by rootstocks. 'Harmony' and '1613C' showed higher K levels by at least 60% in vars. Flame Seedless, Red Globe and Thompson Seedless as compared to plants grown on their own roots. The present investigation demonstrates that rootstocks may have a considerable effect on grapevine nutrition.Se realizaron cuatro ensayos en Vicuña (30°02' S, 70°44' O), Región de Coquimbo, Chile, durante cuatro temporadas, 2002-2003 a 2005-2006 para determinar la influencia de 10 portainjertos de vid ( Vitis vinifera L.) (Freedom, Harmony, Saint George, Salt Creek, SO4, 1613C, 1103P, 99R, 110R, 140Ru, además de plantas sobre sus propias raíces) sobre el contenido de nutrientes en pecíolos de las vars. Flame Seedless, Thompson Seedless, Superior Seedless y Red Globe. Los ensayos se establecieron en un terreno previamente plantado con vides y el diseño experimental fue de bloques completos al azar con cuatro repeticiones. Se colectaron muestras de pecíolos opuestos al racimo en el estado fenológico de floración, para determinar los contenidos de N total, P y K. En las cuatro variedades se encontraron diferencias significativas en los niveles de nutrientes debido al uso de portainjertos. Los portainjertos incrementaron los niveles de nutrientes en pecíolos (excepto P) por sobre los valores reportados generalmente en la literatura para vides de mesa. Las plantas injertadas sobre el portainjerto 'Salt Creek' tuvieron contenidos de N y P en pecíolos significativamente más altos que las plantas sobre sus propias raíces. El nivel de N total aumentó 67% en 'Flame Seedless', 77% en 'Red Globe', 33% en 'Thompson Seedless' y 8,5% en 'Superior Seedless'. Por otro lado, el nivel de P en los pecíolos se duplicó en todas las variedades con el portainjerto 'Salt Creek'. El contenido de K también fue influenciado por los portainjertos. 'Harmony' y '1613C' mostraron valores de K al menos 60% mayores en las vars. Flame Seedless, Red Globe y Thompson Seedless en comparación con las plantas sobre sus propias raíces. La presente investigación demuestra que los portainjertos pueden tener un efecto considerable en la nutrición de las vides

Irrigation Performance Assessment in Table Grape Using the Reflectance-Based Crop Coefficient

In this paper, we present the results of our study on the operational application of the reflectance-based crop coefficient for assessing table grape irrigation requirements. The methodology was applied to provide irrigation advice and to assess the irrigation performance. The net irrigation water requirements (NIWR) simulated using the reflectance-based basal crop coefficient were provided to the farmer during the growing season and compared with the actual irrigation volumes applied. Two treatments were implemented in the field, increasing and reducing the irrigation doses by 25%, respectively, compared to the regular management. The experiment was carried out in a commercial orchard during three consecutive growing seasons in Northern Chile. The NIWR based on the model was approximately 900 mm per season for the orchard at tree maturity. The experimental results demonstrate that the regular irrigation applied covered only 76% of the NIWR for the whole season, and the analysis of monthly and weekly accumulated values indicates several periods of water shortage. The regular management system tended to underestimate the water requirements from October to January and overestimate the water requirements after harvest from February to April. The level of the deficit of water was quantified using such plant physiological parameters as stem water potential, vegetative development (coverage), and fruit productivity. The estimated NIWR was roughly covered in the treatment where the irrigation dose was increased, and the analyses of the crop production and fruit quality point to the relative advantage of this treatment. Finally, we conclude that the proposed approach allows the analysis of irrigation performance on the scale of commercial fields. These analytic capabilities are based on the well-demonstrated relationship of the crop evapotranspiration with the information provided by satellite images, and provide valuable information for irrigation management by identifying periods of water shortage and over-irrigation

Modifications Induced by Rootstocks on Yield, Vigor and Nutritional Status on Vitis vinifera Cv Syrah under Hyper-Arid Conditions in Northern Chile

Hyper-arid regions are characterized by extreme conditions for growing and lack of water (<100 mm annual rainfall average), where desertification renders human activities almost impossible. In addition to the use of irrigation, different viticultural strategies should be taken into account to face the adverse effects of these conditions in which rootstocks may play a crucial role. The research aim was to evaluate the effects of the rootstock on yield, vigor, and petiole nutrient content in Syrah grapevines growing under hyper-arid conditions during five seasons and compare them to ungrafted ones. St. George induced lower yield than 1103 Paulsen. Salt Creek induced higher plant growth vigor and Cu petiole content than ungrafted vines in Syrah, which was correlated to P petiole content. However, Salt Creek and St. George rootstocks induced an excess of vigor in Syrah according to Ravaz Index. Rootstocks with V. berlandieri genetic background should be used in Syrah growing under hyper-arid conditions to maintain adequate levels of plant vigor and to avoid deficiencies or toxicity of macro and micronutrients

Reliability of lumped hydrological modeling in a semi-arid mountainous catchment facing water-use changes

This paper explores the reliability of a hydrological modeling framework in a mesoscale (1515 km(2)) catchment of the dry Andes (30 degrees S) where irrigation water use and snow sublimation represent a significant part of the annual water balance. To this end, a 20-year simulation period encompassing a wide range of climate and water-use conditions was selected to evaluate three types of integrated models referred to as A, B and C. These models share the same runoff generation and routing module but differ in their approach to snowmelt modeling and irrigation water use. Model A relies on a simple degree-day approach to estimate snowmelt rates and assumes that irrigation impacts can be neglected at the catchment scale. Model B ignores irrigation impacts just as Model A but uses an enhanced degree-day approach to account for the effects of net radiation and sublimation on melt rates. Model C relies on the same snowmelt routine as Model B but incorporates irrigation impacts on natural streamflow using a conceptual irrigation module. Overall, the reliability of probabilistic streamflow predictions was greatly improved with Model C, resulting in narrow uncertainty bands and reduced structural errors, notably during dry years. This model-based analysis also stressed the importance of considering sublimation in empirical snowmelt models used in the subtropics, and provided evidence that water abstractions from the unregulated river are impacting on the hydrological response of the system. This work also highlighted areas requiring additional research, including the need for a better conceptualization of runoff generation processes in the dry Andes

Early performance of Olea europaea cv. Arbequina, Picual and Frantoio in the southern Atacama Desert

The cultivars Arbequina, Picual and Frantoio of Olea europaea are cultivated in severalMediterranean countries. In 1999, these cultivars were planted at three locations in the region of Coquimbo,an arid, Mediterranean-like area in Chile. A generalized linear modeling approach was used in view of thenon-normal distribution of the agronomic data sets. Fruit yield (harvests of 2002-2003), precocity (2002) andtree survival (after four growing seasons) differed significantly between the cultivars. Arbequina and Picualhad a positive effect on the yield. Picual was the earliest cultivar at two sites. The survival rate of Frantoio washigh at the three sites (90-100%), as opposed to Picual (56-83%). The approach of Generalized Linear Modelswas particularly useful where the assumption of normality was not satisfied. The selection of cultivars ispromising in this arid region of Chile, while the success will depend on the selection of well-adapted genotypesto a particular location

Effect of Shading Nets on Yield, Leaf Biomass and Petiole Nutrients of a Muscat of Alexandria Vineyard Growing under Hyper-Arid Conditions

Background: Currently, viticulture is exposed to extreme weather fluctuations and global warming, thus the implementation of short-term adaptation strategies to mitigate climate change impacts will be of a wide importance for the sustainability and competitiveness of wine industry. This research aimed to study the effect of shading nets on the viticultural performance of a Muscat of Alexandria vineyard growing under hyper-arid conditions. Methods: Three treatments were randomly arranged in the vineyard: (i) a control (without shading), (ii) a white shading net (25% of shading), and (iii) a black shading net (40% of shading). Subsequently, yield, vine vigor, berry composition, leaf biomass and petiole nutrient content were assessed. Results: Both shading nets decreased the incidence of solar radiation in vines. The application of white shading nets induced a high bunch weight and a higher number of berries per bunch than the black shading nets. Black shading nets increased pruning weight, decreased Ravaz index and induced a considerably accumulation of soluble solids in grapes. This treatment also decreased bunch weight and the number of berries per bunch, and increased rachis length compared to control. Black shading nets decreased Mg petiole content, leaf dry weight and leaf biomass at flowering compared to uncovered vines. Conclusions: Shading considerably affected the viticultural performance of Muscat of Alexandria vines growing under hyper-arid conditions, modifying yield, leaf biomass and petiole nutrients

Evaluación formativa reflexión y acción

Tesis (Profesor de Educación General Básica, Licenciado en Educación)Antes de la Reforma Educacional de 1996, en Chile, se veía el concepto evaluación como una exigencia oficial de calificar a los alumnos y como una herramienta pedagógica interna. "El propósito de la evaluación como se la usa mas frecuentemente en los sistemas educacionales es, ante todo el clasificar y catalogar a los alumnos" (Bloom, 1973) El éxito o fracaso era sólo responsabilidad del alumno. Durante muchos años la evaluación era sinónima de control, sanción y castigo cuando el alumno tenía malas calificaciones y cuando tenía buenas notas, era felicitado, destacado y muchas veces premiado. "Se suponía que la gran parte del éxito o fracaso en el aprendizaje, tenían sus raíces en problemas ajenos a la Escuela y el Profesor estaba libre de cualquier responsabilidad (Bloom, 1973).- Los alumnos comprendían que toda evaluación de su trabajo debía ser reflejada en notas que eran dadas a conocer a terceros (padres o apoderados). Con la aplicación de la Reforma, los Profesores han tenido que enseñar a los alumnos, padres y apoderados a enfrentarse a nuevas estrategias de evaluación y dejar de lado los conceptos de las notas como un elemento esencial en la vida de los estudiantes. Ahora, ante una nueva propuesta pedagógica, que pone énfasis en el aprender más que en el enseñar, debemos reflexionar en que ésta puede tener éxito si se dan algunas condiciones importantes. En nuestro caso su éxito depende de la medida en que cada uno de los profesores de la Unidad Educativa se comprometa a someter a evaluación sus propias prácticas a partir de la evaluación formativa que los retroalimenta , sobre esta base, perfeccione las prácticas que estén acorde con la propuesta pedagógica en marcha o bien modifique algunas que pudieran ser aprendidas por directrices basadas en modelos pedagógicos que, por mucho tiempo orientaron la formación de Docentes y, por lo tanto, el quehacer educativo. Al hablar de someter las prácticas a evaluación , estamos refiriéndonos a la autoevaluación que cada Profesor haga de su labor y también a la evaluación grupal de su quehacer, no para controlar sino para mejorar y enriquecer estas prácticas , Eisnner al analizar los factores que pueden favorecer o dificultar las innovaciones educativas, entre otros menciona uno que denomina el aislamiento del Profesor con relación a sus otros colegas y expresa al respecto que la enseñanza, en general, es una actividad solitaria .(Eisnner, 1992) Si pretendemos que la evaluación se transforme en una ayuda efectiva al aprendizaje, ésta debe ser un desafío que estimule al alumno a dar lo mejor de sí en el proceso de aprendizaje y que no se torne en una angustia para el niño o en una especie de juicio o castigo. Las tendencias actuales apuntan a definir la evaluación como una actividad formadora centrada principalmente en el alumno y no en el producto de éste, por el contrario, la calificación reflejada en una nota, aunque necesaria, desde el punto de vista de la sociedad otorga una información muy restringida que no contribuye al proceso de aprendizaje de los niños

Derivación de la curva de demanda del cobre chileno en el mercado internacional (período 2001- 2012)

The objective of this research is to derive the demand curve of Chilean copper abroad, period 2001-2012, studying its variable factors, with the purpose of generating a mathematical economic model that explains the behavior of Chilean copper demand, for the period from 2001 to 2012, in the international market. Also expose strategies so that Chile can take shelter against external world shock. In accordance, the proposed model is expected to contribute to the fiscal planning capacity of the country and also contribute to the development of economic policies in harmony with those of a developed country, not dependent on a single item.La presente investigación tiene como objetivo derivar la curva de demanda del cobre chileno en el exterior, periodo 2001-2012, estudiando sus factores variables, con el propósito de generar un modelo económico matemático que, explique el comportamiento de la demanda de cobre chileno, para el período comprendido entre los años 2001-2012, en el mercado internacional. También exponer estrategias para que Chile, pueda guarecerse frente a shocks externos mundiales. En conformidad, se espera el modelo planteado aporte a la capacidad de presupuesto nacional y, asimismo, contribuir a elaborar políticas económicas consistentes con las del país desarrollado, no dependiente de un solo rubro