V.12 (2) p. 14-20 | Sergio Rodríguez y Jorge Romero | 65767 | Dat. Num. | Temas Agrarios (Colombia) | (Jul - Dic 2007)

Frijol | V.5 (9) p. 61-72 | Arroz | Maíz | Dat. Num. | Jorge Romero F. y otros | 65768 | (Ene - Jun 2000) | Temas Agrarios (Colombia)

The Tahiti acid lime [Citrus latifolia (Yu Tanaka) Tanaka] is one of the citrus species with production potential for domestic consumption and export in the Eastern plains of Colombia. With purpose to evaluate the effects of the use of agricultural gypsum on the chemical properties, absorption of nutrients and production of fruits of Tahiti lime, was carried an experiment in an Oxisol soil of high terrace of the Llanero Foothills. The treatments consisted of five levels of gypsum (0.5 - 1.0 - 1.5 - 2.0 and 2.5 t ha-1). Was used a design random complete block with four repetitions. The fruit production was evaluated during five consecutive years and in the sixth year; the soil chemical analysis and foliar analysis were carried. A positive effect was found on the increase in the content and distribution of Ca, Mg, and S in the soil profile, decrease in interchangeable acidity and increase in pH with the increasing applications of agricultural gypsum. The gypsum applications increased the absorption of Ca and S and reduced the foliar levels of N, K, Mg and Zn, unchanged the productivity of the crop. The highest accumulated fruit production (141.41 t ha-1) was obtained with the application of 2.5 t ha-1 of gypsum. The positive effects of the agricultural gypsum in the distribution of bases in the soil, in the reduction of the acidity and the increase of the pH in depth were demonstrated, improving the productivity of Tahiti lime.

The root rot of avocado, is a devastating disease in all cultivated areas of Colombia and worldwide. In nurseries and during the first two years of establishment of the crop it is reported losses between 30 and 50% and in the field, incidences of the disease up to 75% are reported. The review is focused to propose alternatives of Integrated Management of the Disease, IDM, involving practices based on four basic principles: sanitation, cultural and biological management, use of resistant root stocks and chemical control. Sanitation, involves all the measures to reduce the possibility to introduce the disease in nurseries, such as: a) sterilization through vapor and use of fumigants in the substrate, b) good ventilation, c) good drainage, and d) seed treatment with hot water or systemic fungicides. The cultural and biological management, refer to development of cultural and biological practices to reduce the incidence of the disease, as planting of seedlings in mounds and application of fungi, such as Trichoderma harzianum, respectively. The use of resistant root stocks, such as Martín Grande G755a, G755b, and G755c, from Guatemala, NATU-001 and CANO-008 from Colombia, and Duke 6, Duke 7 and Thomas, from México, is the best alternative to control the disease, complemented with rational use of protectants fungicides before transplanting of the group of dithiocarbamates and systemics in the field of the groups acylalaninas and phosphonates, such as metalaxyl and fosetyl-Al, respectively. All these practices are focused into the logistic model of Van der Plank.

The objective of this research is to propose a model to articulate Colombian horticultural production chain as a mechanism for managing the interactions between actors for the flow of materials with the cold chain as a logistic-technological tool for the conservation of perishable foods. Based on a sequential construction methodology, a link and segment model is proposed for the Colombian horticultural sector. The model integrates the activities from the input suppliers to the final customer or consumer, identifying their descriptors. Consequently, the cold chain models proposed in the literature are conceptualized and characterized trough a critical control point’s analysis (exogenous and endogenous), based on the HACCP system, selecting the synchronized supply chain model. The joint and superimposed analysis of these two models becomes the articulated design, which allows directing the adaptation of technology in transportation and storage of products under appropriated cold chain conditions for fruits and vegetal products as a competitive advantage.

Potassium is a macronutrient that can improve the growth of crops. A randomized complete block design was used to evaluate the influence of four planting densities (50,000, 41,667, 33,333, 31,250 plants ha-1) and three potassium levels (300, 250, 200 kg of K2O ha-1) on leaf area (AF), leaf area index (LAI), crop growth index (CCI) and harvest index (CI) in potato Solanum tuberosum Phureja var. Criolla Guaneña grown in an area of Botana, Altiplano de Pasto, Nariño, Colombia. All evaluations were measured every 20 days until 120 days after sowing (das), except for the IC at the end of the cycle. Analysis of variance, comparison of Tukey means (P<0.05) and regression among the evaluated variables was performed. The physiological variables presented a significant adjustment to the polynomial models of third degree, quadratic and Hoerl, with coefficients of determination higher than 0.6, indicating that with 31,250 plants ha-1 and 250 kg K2O ha-1 increments were achieved in AF of 6000 cm2 and with 200 kg K2O ha-1 in IAF and ICC of 2.0 and 40 g m2 day-1 between 60 to 80 and 80 to 100 das, respectively; However, with 33,333 plants ha-1 and 250 kg K2O ha-1 the IC (0.70) was increased (P<0.05). Although the regressions showed a tendency to increase the LAI and ICC with the production management practices carried out by the farmers (41,667 plants ha-1 and 250 kg K2O ha-1) between 60 to 80 das, it is not recommended since a lower IC (0.60) was obtained at the end of the cycle.

Los sistemas de monocultivo degradan el suelo afectando sus propiedades físicas y químicas, y su regeneración es muy lenta. Con el objetivo de conocer cambios en las propiedades físicas del suelo de la Estación Experimental Tropical Pichilingue, por efecto del uso, se empleó un diseño de bloques completos al azar con tres repeticiones, en los suelos de bosque nativo y monocultivos de maíz (30 años), cacao (50 años), pasto (4 años) y palma aceitera (26 años) en diferentes profundidades cada 0,10 m hasta los 0,6 m. Se evaluaron propiedades físicas como conductividad hidráulica, densidad aparente, densidad real, porosidad total, porosidad de aireación, humedad volumétrica, textura, arcilla dispersa en agua, grado de floculación, materia orgánica e índice de materia orgánica/ limo+arcilla. Los datos fueron analizados estadísticamente y se realizó la prueba de Tuckey (P≤0,05). Se encontró que maíz, palma aceitera y pasto provocaron incrementos estadísticos significativos en la densidad aparente del suelo sin llegar a sobrepasar los niveles críticos de 1390 kg m-3 y no significativos en reducción de la porosidad total en la profundidad de 0,1-0,2 m. También, hubo alta concentración de arcillas en las primeras profundidades de los suelos cultivados, que provocó susceptibilidad a los procesos de erosión hídrica, concluyendo que el suelo bajo cultivo de palma aceitera mostró mayores diferencias estadísticas debido a la textura, afectando negativamente la densidad aparente del suelo, conductividad hidráulica, arcilla dispersa en agua, que en suma contribuyen a disminuir la estabilidad de agregados.

Monoculture systems degrade the soil, affecting its physical and chemical properties, and its regeneration is very slow. With the objective of knowing changes in the physical properties of the Pichilingue Tropical Experimental Station, due to the use effect, a randomized complete block design with three replications was used in native forest soils and corn monocultures (30 years ), cacao (50 years), pasture (4 years) and oil palm (26 years) at different depths every 0.10 m to 0.6 m. were evaluated physical properties such as hydraulic conductivity, bulk density, real density, total porosity, aeration porosity, volumetric moisture, texture, clay dispersed in water, degree of flocculation, organic matter and organic matter / silt + clay index, The data were statistically analyzed and Separation test Tukey (P≤0.05). It was found that corn, oil palm and grass caused significant statistical increases in the apparent density of the soil without exceeding the critical levels of 1390 kg m-3 and not significant in reducing the total porosity in the depth of 0.1-0.2 m. Also, there was a high concentration of clays in the first depths of the soils under monoculture that caused susceptibility to water erosion processes, concluding that the soil under oil palm cultivation showed greater statistical differences due to the texture, negatively affecting the apparent density of the soil , hydraulic conductivity, clay dispersed in water, which in sum contribute to decrease the stability of aggregates.

El potasio es un macronutriente que puede mejorar el crecimiento de los cultivos. Se empleó un diseño en bloques completos al azar con el objetivo de evaluarla influencia de cuatro densidades de siembra (50.000, 41.667, 33.333, 31.250 plantas ha-1) y tres niveles de potasio (300, 250, 200 kg de K2O ha-1), sobre el área foliar (AF), índice de área foliar (IAF), índice de crecimiento de cultivo (ICC) e índice de cosecha (IC) en papa Solanum tuberosum Grupo Phureja var. Criolla Guaneña cultivada en una zona de Botana, Altiplano de Pasto, Nariño, Colombia. Todas las evaluaciones se midieron cada 20 días hasta los 120 días después de la siembra (dds), menos el IC al final del ciclo. Se realizó análisis de varianza, comparación de medias Tukey (P<0,05) y regresión entre lasvariables evaluadas. Las variables fisiológicas presentaron un ajuste significativo a los modelos polinómico de tercer grado, cuadrático y de Hoerl, con coeficientes de determinación superiores a 0,6, indicando que con 31.250 plantas ha-1 y 250 kg K2O ha-1 se lograron incrementos en AF de 6000 cm2 y con 200 kg K2O ha-1 en IAF e ICC de 2,0 y 40 g m2 día-1 entre 60 a 80 y 80 a 100 dds, respectivamente; sin embargo, con 33.333 plantas ha-1y 250 kg K2O ha-1se incrementó el IC (0,70) (P<0,05). Aunque las regresiones mostraron tendencia a aumentos del IAF e ICC con las prácticas de manejo de producción realizada por los agricultores (41.667 plantas ha-1 y 250 kg K2O ha-1) entre 60 a 80 dds, no se recomienda ya quese obtuvo un menor IC (0,60) al final del ciclo.

El distrito de La Doctrina-Córdoba, aporta a la economía colombiana, con cultivos de arroz (1.230 ha), maíz (50 ha), palma africana (300 ha), papaya (10 ha), hortalizas (8 ha) y 400 ha de pastos. Estos cultivos utilizan plaguicidas ocasionando contaminación en los canales de riego, dichas aguas son utilizadas por los pobladores para uso doméstico y consumo humano. El objetivo de esta investigación fue evaluar las concentraciones de plaguicidas organoclorados (POCls), organofosforados (POFs) y cipermetrina (CP) en aguas de los canales de riego del distrito de La Doctrina en dos épocas del año (seca y lluviosa). Los análisis fueron realizados por Cromatografía de gases y Gases-Masas. La CP se detectó por monitoreo de masas SIM, los POCls y POFs se analizaron con detector de captura de electrones (ECD) y nitrógeno-fosforo (NPD) respectivamente. Los resultados mostraron que todas las concentraciones de CP (época-seca) están por encima del límite aceptado según la norma colombiana para agua potable, según la norma Argentina todos sobrepasan los límites permisibles. Entre los POCls solo el Endrín sobrepasó la norma colombiana, no se encontraron POFs. Los porcentajes de aparición individual de plaguicidas muestran el valor más alto para cipermetrina con un 73%. Las altas concentraciones de CP y POCls, en el agua de riego en el distrito La Doctrina, generan un alto interés por la detección de las concentraciones de estos contaminantes es alimentos como el arroz y un alto riesgo a la salud humana.