El experimento se realizó en el Centro Agropecuario Marengo de la Universidad Nacional de Colombia, ubicado en el kilómetro 12 vía Bogotá-Mosquera, coordenadas 4° 42’ N 74° 12’ W, a 2.516 msnm, temperatura media 13,7 ºC, precipitación 669,9 mm·año-1 y brillo solar 4,2 h diarias. En tres parcelas de 300 m² cada una, con 8,3 y 11,1 plantas/m² para brócoli y repollo respectivamente, regadas con aguas del distrito La Ramada, se realizaron muestreos cada ocho días, se midió el área foliar, el peso seco, la temperatura media y horas de brillo solar. Las horas de brillo solar se transformaron en radiación fotosintéticamente activa (PAR). Se usó un modelo matemático multiplicativo determinístico con los siguientes componentes: PAR, fracción de luz interceptada (FLINT), en función del índice de área foliar, del coeficiente de extinción (k) y uso eficiente de la luz (LUE). La masa seca total y su partición de acuerdo con los órganos de la planta, se simuló con el método de integración de Euler. Se estimó k igual a 0,5120 y 0,5052, LUE igual a 0,2289 y 0,1181 g·MJ-1 para brócoli y repollo, respectivamente. En brócoli, el 32,72% y 30% de la masa seca se distribuyó en el tallo; el 45,28% y el 30%, en las hojas; el 22% y el 17,83%, en la raíz en las etapas vegetativas y reproductiva, respectivamente. En repollo se distribuyó el 28,41% en el tallo; el 65,28%, en las hojas y el 6,31%, en la raíz.
The experiment was carried out in the Agricultural Center Marengo of the National University of Colombia located on the km 12 route Bogotá-Mosquera with coordinates 4° 42’ N 74° 12’ W, at 2,516 m a.s.l. 13.7 ºC average temperature, 669.9 mm/year precipitation, 4.2 h daily light. Three plots with 300 m² each one, with 8.3 and 11.1 plants/m² for broccoli and cabbage, respectively, were applied with water of the district The Ramada. The samplings were realized every 8 days with 7 and 8 samplings for broccoli and cabbage, respectively. Leaf area, dry weight, hours of light and average temperature were measured. The light hours were transformed in photosynthetically active radiation (PAR). Deterministic multiplicative mathematical model was used taking into account the following components: Photosynthetic active radiation (PAR), fraction of intercepted light (FLINT), which depends on the leaf area index and, the coefficient of extinction parameter k, and the parameter light use efficiency (LUE). The entire plant dry weight and its partition among the plant organs were simulated by the method of integration of Euler. Parameters k as 0.5120 and 0.5052, and LUE as 0.2289 and 0.1181 g·MJ-1 were estimated for broccoli and cabbage, respectively. The percentage of dry weight distributed during the vegetative and reproductive stages were 32.72 and 30% in the stem, 45.28 and 30% in the leaves, and 22 and 17.83% in the root. In cabbage, the dry weight distribution was 28.41% in the stem, 65.28% in the leaves, and 6.31% in the root.