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<p>En el municipio de San Antonio del Tequendama (Cundinamarca, Colombia) se esta incentivando la siembra del cultivo de lulo, pero se desconocen muchos aspectos relacionados con la fisiologia y el manejo de la especie en estas condiciones agroecologicas. El objetivo fue realizar el estudio del crecimiento y desarrollo del fruto de lulo cultivar var. Septentrionale. Para lo cual se marcaron flores en antesis y se hicieron nueve muestreos de frutos del tercio medio de las plantas cada 20 dias. En cada muestreo se determinaron las siguientes variables: masa fresca y seca de los frutos, firmeza, solidos solubles totales, acidez total titulable e intensidad respiratoria. A los 180 dias, despues de la antesis (DDA), los frutos alcanzaron la madurez de cosecha con una coloracion naranja intensa y una masa promedio de 209 g. El comportamiento de la masa fresca y la masa seca del fruto fue sigmoideo simple lo cual se ajusta a un modelo no lineal de tipo logistico. La acidez total titulable y los solidos solubles totales se incrementaron con el desarrollo del fruto, mientras que la intensidad respiratoria disminuyo y la firmeza aumento hasta los 80 DDA para luego disminuir hasta la cosecha. La tasa absoluta de crecimiento (TAC) se incremento rapidamente y alcanzo su maximo valor</p>

The pitahaya or dragon fruit is one of the most representative exotic fruits that Colombia has, with an important, growing international market, but the cultivation and postharvest of this fruit lack sufficient technological support to be more competitive. Therefore, alternatives that provide good-quality products that meet market requirements are very important. Therefore, the objective of this research was to determine the effect of a ripening retardant and ethylene application on the conservation and quality of pitahaya fruits and the possible changes during ripening associated with ethylene, for which a completely randomized design with three treatments was used, corresponding to the application of ethylene (ethephon, 3 mL L-1), 1-methylcyclopropene (1-MCP, 600 mg L-1) and a control, with four replications, for a total of 12 experimental units. The fruits were stored at 18°C with 75% relative humidity. The 1-MCP application significantly decreased the loss of firmness, total soluble solids, loss of fresh mass and respiratory rate. Fruits from the control and ethylene treatment tended toward a climateric respiratory behavior. The total carotenoid content of the fruits was significantly higher in the ethylene application and the control treatment, which was consistent with the color change of the fruits. It can be concluded that the 1-MCP application reduced the ethylene action, slowing the ripening of the dragon fruits.

Oil palm (Elaeis guineensis Jacq) is an alternative for the development of productive systems in the tropics. By determining the spatial variability of physical characteristics of soil, specific recommendations for certain areas within a zone can be made. Geostatistical analysis can determine the existence and characteristics of the spatial distribution and is an appropriate tool for analyzing the spatial variability of soil properties. The aim of this study was to determine areas with homogeneous physical characteristics in order to establish agricultural management units, using geostatistical techniques. For this study, 62 samples were collected in 10.6 ha in the municipality of El Retén (Magdalena, Colombia). The properties analyzed were: content of sand, silt and clay, particle density, bulk density, total porosity, gravimetric and volumetric water content, hydraulic conductivity and infiltration rate. All properties showed spatial correlation, with adjustments to semivariograms theoretical models, mostly to the spherical model, with ranges between 84.87 and 218.60 m and moderate to strong spatial dependence. The contour maps obtained through ordinary kriging, allowed for the identification of the relationship between the different physical properties of the soil and subsequent classification to determine the Agronomic Management Units (AMU).

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