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Copyright of Revista Facultad de Medicina de la Universidad Nacional de Colombia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Innovar: Revista de Ciencias Administrativas y Sociales is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Innovar: Revista de Ciencias Administrativas y Sociales is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ensayos de Economia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents a review on hydrogels applied to agriculture emphasizing on the use of natural fibers. The objectives were to examine, trends in research addressed to identify natural fibers used in hydrogels development and methods for modifying natural fibers, understand factors which determine the water retention capacity of a hydrogel. Consequently, this paper shows some methodologies used to evaluate the hydrogels efficiency and to collect in tables, relevant information in relation to methods of natural fibers modification and hydrogel synthesis. It was found that previous research focused on hydrogels development processed with biodegradable polymers such as starch, chitosan and modified natural fibers, cross-linked with potassium acrylate and acrylamide, respectively. In addition, current researches aimed to obtaining hydrogels with improved properties, which have allowed a resistance to climatic variations and soil physicochemical changes, such as pH, presence of salts, temperature and composition. In fact, natural fibers such as sugarcane, agave fiber and kapok fiber, modified with maleic anhydride, are an alternative to obtain hydrogels due to an increasing of mechanical properties and chemically active sites. However, the use of natural nanofibers in hydrogels, has been a successful proposal to improve hydrogels mechanical and swelling properties, since they give to material an elasticity and rigidity properties. A hydrogel efficiency applied to soil, is measured throughout properties as swellability, mechanical strength, and soil water retention. It was concluded that hydrogels, are an alternative to the current needs for the agricultural sector.

In the majority of developing countries the research on the cellulolytic microorganisms has been scarcely oriented to the transformation of organic solid waste into compost, ignoring their enormous industrial potential. The main objective of the present investigation was to generate information on the capacity and diversity of the cellulolytic bacteria isolated from three different habitats. The study included soil samples from native forests and cereal producing farms as well as from compost piles. From each sample, a serial dilution until 10-4 was prepared and from each dilution test tubes containing liquid mineral medium and a strip of filter paper as a source of cellulose were inoculated. After three weeks of incubation, the population density of the cellulolytic microorganisms was estimated and from the filter paper strips streaks were made on nutrient agar medium and then on solid mineral medium, supplemented with cellulose. The bacterial growths were submitted to the Congo Red test and the ones with the greater potential were identified. In comparison to the soils the compost piles harbor a higher population density of cellulolytic microorganisms. In respect to the cellulolytic bacteria, in total were obtained 20 isolates, 19 from the native forests and 1 from a compost pile. Isolates 1, 2, 6, 7 and 14 showed a higher cellulolytic capacity with halos of hydrolysis between 0.65 and 0.30 cm. Isolate 1 was identified as Bacillus sp, isolate 7 as Pseudomonas sp, and isolate 6 as Erwinia sp. This information is useful to explore with confidence the potential of the cellulolytic bacteria in the industry.

Copyright of Cuadernos de Geografia: Revista Colombiana de Geografía is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Colombiana de Biotecnología is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In Soconusco, Chiapas, in spite of the high availability of surface water, it is resorting to the use of groundwater. Knowledge about the quality of surface or groundwater used to irrigate crops in that region is low. This paper aims to contribute to the knowledge of the quality of groundwater for agricultural use through the characterization of the spatial variability. Assuming a random spatial distribution of 45 samples which were collected in situ were determined: acidity and alkalinity (pH), electrical conductivity (EC), Total Dissolved Solids (TDS), cations and anions and trace elements; in addition to the agricultural index: Sodium Adsorption Ratio (SAR), Residual Sodium Carbonate (RSC), Soluble Sodium Percentage (SSP), Sodium Percentage (% Na), Kelly Ratio (KR), Magnesium Adsorption Ratio (MAR), Permeability Index (PI), Effective Salinity (ES), Salinity Potential (SP) and Osmotic Potential (OP). In general, SSP, % Na, KR, PI are low, there is only one anomalous point (9) with high values at W of the study area. Similarly, PS, ES, Cl, Na and SAR are low except point 16 and conversely, RSC and pH are high, except at this point located in the center of the study area. The results allow us to infer that the water in that aquifer presents no problems or sodicity toxic ions. In 27 sites sampled values above 250 µmhos/cm were found at 25°C, classified as medium to high risk of salinity, unsuitable for agricultural use. Analysis of the combined effect of the presence of sodium (SAR) and salinity (EC or TDS) shows that 27 of analyzing sites have restricted water medium at very high for use in irrigation. [ABSTRACT FROM AUTHOR]

This paper suggests a hybrid model to solve a distribution problem incorporating the impact of uncertainty in the solution. The model combines the deterministic approach and the simulation including stochastic variables such as harvest yield, loss risk and penalties/benefits to design a distribution network with the minimal cost. Through a case study that includes farmers, hubs and malt producers in the supplying chain of barley in Mexico, nine possible scenarios were analyzed to plan and distribute the harvested grain based on contract farming. This approach gets an optimal solution through an iterative process simulating the suggested solution by a mixed-integer linear programming model under uncertain conditions. The results show the convenience of maintaining the operation between four and five hubs depending on the possible scenario; besides, the variation of the levels of the barley producers’ capacities are key elements in the planning to minimize the distribution cost throughout the suggested chain

Harvesting palm oil crops involve different risk factors that decrease workers’ safety and physical integrity. This paper compares stress on the lower back when using the conventional tool and a new cutting system for cutting bunches. The biomechanical analysis is carried out using simulations generated by JACK Siemens software. The study found a 95.97% reduction of intradiscal compression (L4/L5) when cutting bunches and showed that pressure on all joints was reduced, in certain cases, such as the back and elbow, by up to 100%. That is, when cutting using the new system, the worker maintains a neutral posture of the spine. The new design comprises a point of support on which the tool rests and means that workers only have to direct the blade. Future studies should compare both tools in terms of productivity while preserving the ergonomic characteristics.

The aim of this study was to evaluate the chemical control of Asian soybean rust (Phakopsora pachyrhizi Syd. & P. Syd.) using different tips and spray nozzles under controlled conditions. Rooted trifolia placed inside an acrylic box containing macronutrients, micronutrients and vitamins were treated with epoxiconazol + pyraclostrobin, ciproconazol + azoxystrobin and tebuconazol fungicides. These fungicides were sprayed at a height of 0.5 m with two knapsack sprayers pressurized with CO2 gas (drop generator in four spray tips spaced by 0.5 m from each other) and another rotating nozzle (drop generator through a rotating nozzle). Untreated trifolia were controls. Water sensitive paper was placed next to each acrylic box to obtain median volume diameter (MVD), number of droplets.cm-2 and coverage (%). Trifolia were inoculated 24 hours after that these were treated with fungicide, using a spore concentration adjusted to 2 x 104 uredospores.mL-1. Then, the number of lesions and uredia.cm-2 in central leaflets were quantified. Lower number of lesions and uredia.cm-2 were observed in leaflets treated with two fungicide mixtures using an AIRMIX 11001 tip. A lower VMD was found in leaflets sprayed with the fungicides azoxystrobin + epoxiconazol and tebuconazol, when compared to the leaflets treated with another mixture. The Asian rust control, as well as the number of droplets.cm-2 and coverage, seems to be dependent on the interactions among fungicides and tips or nozzles.

The aim of this paper is to build a supervised intelligent classification model of food products such as Biscuits, Cereals, Vegetables, Edible nuts and etc., using digital images. The Correlation-based Feature Selection (CFS) algorithm and 2nd derivative pre-treatments of the Morphological, Colour and Texture features are used to train the models for classification and detection. The best prediction accuracy is obtained for the Multilayer Perceptron (MLP), Support Vector Machines (SVM), Random Forest (RF), Simple Logistic (SLOG) and Sequential Minimal Optimization (SMO) classifiers (more than 80% of the success rate for the training/test set and 80% for the validation set). The percentage of correctly classified instances is very high in these models and ranged from 80% to 96% for the training/test set and up to 95% for the validation set.

For each vegetable species, there is a specific environment conditions to occur the seed germination process. However, there is a little information regarding the necessary conditions for Niger (Guizotia abyssinica (L.f.) Cass.) seeds germination. The aim of this research was to evaluate the influence of different temperatures and types of light on Niger (Guizotia abyssinica (L.f.) Cass.) seeds germination. Seeds were sown on two sheets of “germitest” paper inside plastic box type “gerbox” and placed on B.O.D. Treatments were constituted of two constant temperatures (15 ºC and 25 ºC, respectively) and an alternating temperature (20-30 ºC) under 10 hours for the lowest temperature and 14 hours for the highest temperature and they were associated to the wavelengths as follows: blue (440 nm), green (560 nm), red (660 nm), extreme red (730 nm), white light and dark. The experiment was conducted in a completely randomized design with four replicates of 50 seeds. Effects of different temperatures and qualities of light were evaluated by seeds germination and vigor. Higher germination of Niger seeds is observed in temperatures of 25 and 20-30 ºC and they can be considered as non-photoblastic.

This paper presents the conceptualization, methodological adjustment and experimental application of the micrometeorological technique eddy covariance - EC, to measure energy, water vapor and CO2 fluxes in two coffee agroecosystems: the first under full sunlight, and the second under shade, both with equatorial Andean hillslope conditions. With a footprint and fetch calculation, the required distance from the edge of the field in the prevailing wind direction to the EC tower is three times higher under shade than full sun. The shaded agroecosystem reached maximum average carbon fixation rates of 21.26 ± 2.469 μmolCO2.m-2s-1 ( = 0.05) (61% higher than under 100% sunlight) which gives a high carbon sink capacity to the association of coffee plants with shading Pigeon peas (Cajanus cajan L). The average evapotranspiration rate was 2.33 ± 0.0102 mm.d-1 ( = 0.05) and 2.08 ± 0.00732 mm.d-1 under shade and 100% sunlight, respectively. The proportion of net radiation that reached the soil was 2% under shade and 4% under 100% sunlight. Likewise, the soil energy loss during the night was lower under shade, indicating less day-night temperature range in the latter agroecosystem. The methodological adjustment and the results of this first work using EC in Colombian coffee plantations, contribute to the development of reliable research regarding gas and energy exchanges between the atmosphere and ecosystems in conditions of the equatorial Andean hillslope.

Copyright of Agronomía Colombiana is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ensayos de Economia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Las redes neuronales artificiales, simuladoras del proceso de aprendizaje de las neuronas biológicas, han sido utilizadas con éxito en el cálculo de parámetros en diversos problemas de ingeniería en que las variables involucradas tienen una alta relación no lineal entre sí y la modelación no permite representar el problema mediante una función matemática de fácil deducción. En la ciencia del suelo la predicción de algunas propiedades involucra diversas variables que hacen de su estimación por medio de modelos matemáticos un proceso complejo, y trasladan la solución del problema al campo de la inteligencia artificial. En el presente artículo se reporta la elaboración de redes neuronales artificiales para la estimación de la resistencia a la penetración a diferentes profundidades de un suelo; se consideran como variables influyentes el contenido de humedad, la densidad, la carga estática y la presión de inflado. Los resultados muestran una mejor estimación para profundidades entre 20 cm y 30 cm.Artificial Neural Networks simulate the learning process of biological neurons, and these have been successfully used in the computation of parameters on several engineering problems where exist a strong nonlinear relation among the variables. In soil science, estimation of some properties involves variables that are complicated to estimate using mathematical models, so the solution for the problems fall into the field of Artificial Intelligence. The present paper reports the elaboration of an Artificial Neural Network for the estimation of penetration resistance of soil at different depths, considering as influential variables humidity, density, static load, and inflate pressure. The best estimation results were obtained at a depth of 20-30 cm.

Aunque los modelos climáticos globales muestran que cada vez son más altas las tasas de cambio de la temperatura y la precipitación, no proporcionan la información necesaria para que los actores del sistema producción-consumo puedan definir las medidas de adaptación a escala local. En el presente trabajo se demuestra de qué manera se pueden generar escenarios de cambio climático más locales, basados en el análisis de las tendencias de las series de tiempo de los elementos del clima. Se plantea la prueba de Mann-Kendall para determinar si existe tendencia en las series temporales de dos elementos climáticos y el análisis espectral singular para generar escenarios futuros de las variables climáticas analizadas. Los resultados mostraron que en dos municipios de Colombia (El Espinal, Tolima, y Mosquera, Cundinamarca) los pastos pará (Brachiaria mutica) y kikuyo (Pennisetum clandestinum), respectivamente, tienden a requerir más agua por aumento de la evapotranspiración, sin embargo, es la textura del suelo la que determina cambios drásticos entre escenarios climáticos, en términos de requerimientos de riego.Even though climate change simulation shows higher temperature and precipitation rate shift, it does not provide enough information to the definition of adaptation measures to climate change at local scale. This paper intends to show how climate change local scenarios could be generated by time series trend analysis of climatic factors. Mann-Kendall test was used to determine trends in time series of two climatic factors and spectrum singular analysis to generate future scenario of the analyzed factors. The outputs showed, in both localities (El Espinal, Tolima, y Mosquera, Cundinamarca) the pasture pasto pará, Brachiaria mutica, and kikuyo, Pennisetum clandestinum, respectible, tends to require more water due to higher evapotranspiration rate, although, soils texture determinates drastic changes between the two generated climatic change scenario, irrigation requirement related.

Laboratory tests with seed of Calendula officinalis and Anethum graveolens to describe morphology and anatomy components such as humidity content in balance (CHB) in different atmospheres to get appropriate conservation of the germsplasm to determine physiological behavior in short seed storage to evaluate and to stablish an appropriate methodology for germination, were carried out. The morphological and anatomical description allowed to specify and to illustrate the organs and internal structures of the seed in detail. Also this procedure was important to clarify certain aspects that were managed in wrong way with these species like to confuse the fruit with the seed. It was possible to reach CHB in different atmospheres with artificial drying using the methodology of drying curves with sílica gel in relations of weight-sílica- seed of 10:1, 7:1 and 5:1, besides recommending a method and appropriate relations to conserve the germplasm. The ortodoxal physiological behavior of the seeds of this species was determined. Germination tests were carried out under different methodologies and materials that statistically didn't show influence on the germination of the seeds. For practical purposes, the sowing methodology in Petri dishes with absorbing paper was recommended. Also this methodology was achieved to identify and to illustrate normal and abnormal plants and seeds of this species that died. .En semillas de caléndula Calendula officinalis y de eneldo Anethum graveolens, se realizaron la descripción morfológica y anatómica y mediciones del contenido de humedad en equilibrio (CHE). La descripción morfológica y anatómica permitió precisar e ilustrar detalladamente los órganos y tejidos internos de la semilla, además, clarificar aspectos en la definición de semilla pura de caléndula. Se elaboraron curvas de secado y se midió el CHE en diferentes ambientes de secamiento artificial, obtenidos con la metodología de curvas de secado con sílica gel en relaciones de peso sílica-semilla de 10:1, 7:1 y 5:1, además de identificar un método y una relación adecuados para la conservación del germoplasma. Se determinó el comportamiento fisiológico ortodoxo en almacenamiento a corto plazo de las semillas de estas especies. Las diferentes metodologías y sustratos no mostraron diferencia significativa sobre la germinación de las semillas; por facilidad se propone la siembra en cajas Petri con papel absorbente. Además, se logró tipificar e ilustrar plántulas normales, anormales y semillas muertas.

En semillas de caléndula Calendula officinalis y de eneldo Anethum graveolens , se realizaron la descripción morfológica y anatómica y mediciones del contenido de humedad en equilibrio (CHE). La descripción morfológica y anatómica permitió precisar e ilustrar detalladamente los órganos y tejidos internos de la semilla, además, clarificar aspectos en la definición de semilla pura de caléndula. Se elaboraron curvas de secado y se midió el CHE en diferentes ambientes de secamiento artificial, obtenidos con la metodología de curvas de secado con sílica gel en relaciones de peso sílica-semilla de 10:1, 7:1 y 5:1, además de identificar un método y una relación adecuados para la conservación del germoplasma. Se determinó el comportamiento fisiológico ortodoxo en almacenamiento a corto plazo de las semillas de estas especies. Las diferentes metodologías y sustratos no mostraron diferencia significativa sobre la germinación de las semillas; por facilidad se propone la siembra en cajas Petri con papel absorbente. Además, se logró tipificar e ilustrar plántulas normales, anormales y semillas muertas.Laboratory tests with seed of Calendula officinalis and Anethum graveolens to describe morphology and anatomy components such as humidity content in balance (CHB) in different atmospheres to get appropriate conservation of the germsplasm to determine physiological behavior in short seed storage to evaluate and to stablish an appropriate methodology for germination, were carried out. The morphological and anatomical description allowed to specify and to illustrate the organs and internal structures of the seed in detail. Also this procedure was important to clarify certain aspects that were managed in wrong way with these species like to confuse the fruit with the seed. It was possible to reach CHB in different atmospheres with artificial drying using the methodology of drying curves with sílica gel in relations of weight-sílica- seed of 10:1, 7:1 and 5:1, besides recommending a method and appropriate relations to conserve the germplasm. The ortodoxal physiological behavior of the seeds of this species was determined. Germination tests were carried out under different methodologies and materials that statistically didn't show influence on the germination of the seeds. For practical purposes, the sowing methodology in Petri dishes with absorbing paper was recommended. Also this methodology was achieved to identify and to illustrate normal and abnormal plants and seeds of this species that died.

Copyright of Cuadernos de Geografia: Revista Colombiana de Geografía is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Colombiana de Biotecnología is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The thyroid gland were reported in adaptation to climate variations, specially to dairy cows. The objetive of present paper is study thyroid function in the diversus breeds under tropical environmental conditions. The breeds were: Holstein Friesian, BON (White Ear-Black, native breed of Colombia), Gucerat, Holstein X Gucerat, BON x Gucerat, Brown Swiss x Gucerat. The Serie levels of T) and T4 were analized for RIA Technique; the interval partum-partum (IPP) is evaluated for individual breed. The relationships of the thyroids hormones levels with IPP showed statistical difference for BON and Holstein breeds. It is a adaptative conditions for native BON's breed.Se estudiaron los valores de T3 y T4 en seis grupos raciales, 5 de origen Bos taurus y uno Bos indicus, en simulares Condiciones de ecohabitat, nutrición y manejo con el fin de dilucidar los valores hormonales y su posible relación con el comportamiento reproductivo, medido como intervalo entre partos (lEP). Los valores séricos de T3 (1.39 ± 0.31 nmol/L) y T4 (41.84 ± 8.89 nmol/L), en 85 vacas multíparas se encuentran dentro de los valores de referencia reportados. El análisis estadístico mostró diferencias significativas (P4 y Holstein Friesian (1.628 ± 0.453 T3 y 43.353 ± 10.461 T4 lo cual permite plantear que la adaptación de animales productivos en condiciones tropicales se puede estudiar mediante la valoración endocrina de la actividad tiroidea. El intervalo entre partos (416.15 días), se puede considerar como aceptable para las condiciones del estudio.

This paper reports the results of a study on estimation of genetic parameters of yield, number of fruits per plant and average fruit weight characters in tomato, Lycopersicon esculentum, Mill. The experimental material consisted of four inbred lines and all possible F1's from these lines (not including reciprocals). Statistical and genetic analysis were made by model 2, method 2 proposed by Griffing (1956). Non-additive gene effects which considerable higher than the additive gene effects wich in turn were also significant for the characters yield and number of fruits per plant. Both non additive gene effects and additive gene effects were significant for the character average fruit weight. A positive correlation was found between yield and average fruit weight. Yield was negatively correlated with number of fruit per plant. The average fruit weight was negatively correlated with number of fruits per plant. In as much non-additive effects are important in yield and number of fruits per plant a program exploiting heterosis should prove effective in improvement these characters. A program designed for simultaneous improvement for both additive and non-additive gene action should provide improvement in average fruit weitht. En una población dialélica, compuesta por cuatro líneas endocriadas y todos los posibles híbridos F1, sin incluir los recíprocos, se estimaron los principales parámetros genéticos para el carácter rendimiento y sus componentes primarios. El análisis genético-estadístico se realizó utilizando el modelo 2, método 2 propuesto por Griffing (1956). Los efectos genéticos no aditivos fueron más importantes y significativos para los caracteres rendimiento y número de frutos por planta. Para el carácter peso promedio de fruto, tanto los efectos génicos no aditivos como aditivos fueron importantes y significativos. Se encontró correlación positiva entre rendimiento y peso promedio de fruto. El rendimiento estuvo correlacionado negativamente con el número de frutos por planta. El peso promedio de fruto estuvo correlacionado negativamente con el número de frutos por planta. Se discuten algunos métodos de mejoramiento que se pueden usar en esta especie con base en los parámetros genéticos obtenidos.

This paper reports the results of a study on genetic and environmental variability between 43 lines of "Chonto" tomato, Lycopersicon esculentum Mill, without using progeny offspring test. The experimental material were planted under field conditions using three randomized blocks. Data on individual plants were recorded for yield/plant, number of fruit/plant, average fruit weight, number of inflorescences/plant, number of fruits/inflorescence, number of locules/fruit, average locule weight, fruit shape index, pericarp thickness, days to flowering, harvest lenght, plant heigh, first inflorescence heigh, internode lenght, reaction to the presence of Scrobipalpula absoluta and Xanthomonas vesicatoria. The quantitative characters were subjeted to variance analysis in orden to evaluate the genetic and environmental variation. Heritability in the wide sense, genetic variability coeficient and the expected progress by selection were estimated. Fenotipic, environmental and genetic correlations among some evaluated characters were also carried out. Important genotipic differences, at 1% of probability, for the evaluated characters were found. Generally, in the most of the evaluated characters the largest contribution of the total variation correspond to the genetic variation. The contribution of the environmental variation was very low.Con el fin de analizar la variabilidad genética y ambiental, de algunos caracteres agronómicos importantes en tomate "chonto" se evaluaron 43 líneas, en condiciones de campo utilizando un diseño experimental de bloques al azar con tres repeticiones. Los datos experimentales se obtuvieron a partir de tres plantas individuales por repetición y en plena competencia. Se evaluaron los siguientes caracteres cuantitativos: producción por planta, número de frutos por planta, peso promedio de frutos, número de inflorescencias por planta, número de frutos por inflorescencias, número de lóculos por fruto, peso promedio de lóculos, formato de fruto, grosor de pericarpio, días a primera flor abierta, duración de la cosecha, altura de la planta en el momento de la cosecha, altura de la primera inflorescencia y longitud del primer entrenudo. Se realizó el análisis de varianza con miras a evaluar la varianza genética y la varianza ambiental, heredabilidad en el sentido amplio, coeficiente de varianza genética y progreso esperado por selección. También se efectuaron correlaciones fenotípicas, genotípicas y ambientales entre algunos caracteres evaluados. Se encontraron diferencias genotípicas al 1% de probabilidad, para todos los caracteres evaluados. Para la mayoría de los caracteres evaluados, la varianza genética obtuvo mayor contribución a la varianza fenotípica. El aporte de la varianza ambiental fue muy bajo.

En una población dialélica, compuesta por cuatro líneas endocriadas y todos los posibles híbridos F1 sin inc1uír los recíprocos, se estimaron los principales parámetros genéticos para el carácter rendimiento y sus componentes primarios. El análisis genético-estadístico se realizó utilizando el modelo 2, método 2 propuesto por Griffing (1956). Los efectos genéticos no aditivos fueron más importantes y significativos para los caracteres rendimiento y número de frutos por planta. Para el carácter peso promedio de fruto, tanto los efectos génicos no aditivos como aditivos fueron importantes y significativos. Se encontró correlación positiva entre rendimiento y peso promedio de fruto. El rendimiento y peso promedio estuvo correlacionado negativamente con el número de frutos por planta. Se discuten algunos métodos de mejoramiento que se pueden usar en esta especie con base en los parámetros genéticos obtenidos.This paper reports the results of a study on estimation of genetic parameters of yield, number of fruits per plant and average fruit weight characters in tomato, Lycopersicon esculentum, Mill. The experimental material consisted of tour inbred lines and all possible F,'s from these lines (not including reciprocals). Statistical and genetic analysis were made by model 2, method 2 proposed by Griffing (1956). Non-additive gene effects which considerable higher than the additive gene effects wich in turn were also significant for the characters yield and number of fruits per plant. Both non additive gene effects and additive gene effects were significant for the character average fruit weight. A positive correlation was found between yield and average fruit weight. Yield was negatively correlated with number of fruit per plant. The average fruit weight was negatively correlated with number of fruits per plant. In as much non-additive effects are important in yield and number of fruits per plant a programa exploiting heterosis should prove effective in improvement these characters. A programa designed for simultaneous improvement for both additive and non-additive gene action should provide improvement in average fruit weitht.

En la hacienda Los Andes, ubicada en el municipio de San Sebastián, departamento del Cauca, Colombia (2.700 m.s.n.m.), se adelantó un estudio acerca de las características hidráulicas de sus suelos, determinados por un alto contenido de materia orgánica (suelos orgánicos). Se encontró que a pesar de la alta porosidad que puede presentar un suelo orgánico, su permeabilidad no necesariamente, responde directamente a esta característica, porque está dominada esencialmente por microporos. El mal drenaje de estos suelos (encharcamiento), está determinado por la alta capacidad de almacenamiento de agua de su vegetación natural, el musgo, el cual a su vez tiene baja transmisibilidad. Se describen los procesos mediante los cuales los agricultores adecuan los suelos para el uso agrícola.A study about the hydraulic characteristics of the organic soil in a farm located at Paramo de Las Papas (2700 m.a.s.l.), Colombia, was carried out. It was found that permeability is not directly related with the high porosity of this type of soils. The present water logging is determined by the high water holding capacity of the surface vegetation, that is constitued by moss species, material that have a low transmisibility. In this paper, the proccess by which farmers reclaim the soils for cultivation, is described too.

Se localizaron poblaciones de la planta en los municipios de Santa Rosa-Cauca y de Mocoa-Putumayo y se hicieron observaciones fenológicas discontinuas entre abril de 1984 y agosto de 1986; simultáneamente se realizaron ensayos de propagación sexual y asexual (estacas y acodos). La floración, fructificación y emisión de follaje se presentaron con cierta periodicidad durante el período de observaciones, en tanto que la caída de follaje no ocurrió en volúmenes apreciables. Los ensayos de propagación sexual fracasaron, mientras que el enraizamiento de estacas, aún utilizando enraizadores, fue muy bajo (6.5 %); las únicas estacas que enraizaron fueron las terminales sembradas con yema foliar y hojas apicales. Todos los acodos formaron callo pero enraizaron más los tratados con enraizadores (75 %).This paper presents phenological, sexual and asexual propagation observations of Elaeagia pastoensis Mora, furthermore some botanic and ecology aspects of the plant were conssidered. The plant was found growing in Santa Rosa-Cauca and Mocoa-Putumayo municipalities where discontinual phenological observations were made; sexual and asexual (stem cutting and aereal layer) propagation experiments were made too. The field work carried out through april 1984 and august1986. Flowering, fruiting and leaf flushing appeared with some regularity during the observations period; the leaf fall was not observed in siqnificant quantyties. The sexual propagations was not sucesfully. The percentage of root setting taken from terminal of the branch with resinal bud leaves and apical leaves set roots. AII aerel layer formed callus, however the hi- ghest percentage of root setting (75%) was reached with treated ones with hormones.