Se utilizó el modelo regionalizado de lluvia Regionalisierte Niederschlage (Regnie) para interpolar la lluvia y temperatura media del aire de las regiones Andina, Caribe y Pacífica de Colombia. Este modelo integró los datos de la pendiente y exposición del terreno obtenidos del modelo digital de elevación, así como los promedios climatológicos de 1440 series de precipitación y 258 series de temperatura registradas en igual número de estaciones meteorológicas de superficie para cada variable. Se establecieron los modelos de regresión lineal múltiple de la precipitación media anual y temperatura media anual del aire, además se utilizaron herramientas de geoprocesamiento para la generación de las superficies interpoladas. Los estadísticos de prueba de las superficies Regnie fueron similares a los obtenidos con interpolaciones con los métodos Spline e IDW para precipitación (coeficiente de determinación 0.81 y error medio de 55.6 mm) y mejores para la temperatura media (coeficiente de determinación 0.99 y error medio de 0.02°C).
Potato farming is relevant for global carbon balances and greenhouse emissions, of which gross primary productivity (GPP) is one of the main drivers. In this study, the net carbon ecosystem exchange (NEE) was measured using the Eddy Covariance (EC) method in two potato crops, one of them with an irrigation system, the other under rainfed conditions. Accurate NEE partition into GPP and ecosystem respiration (RECO) was carried out by fitting a light response curve. Direct measurements of dry weight and leaf area were performed from sowing to the end of canopy life cycle and tuber bulking. Agricultural drought in the rainfed crop resulted in limited GPP rate, low leaf area index (LAI), and low canopy carbon assimilation response to the photosynthetically active radiation (PAR). Hence, in this crop, there was lower efficiency in tuber biomass gain and NEE sum indicated net carbon emissions to atmosphere (NEE = 154.7 g C m−2 ± 30.21). In contrast, the irrigated crop showed higher GPP rate and acted as a carbon sink (NEE = −366.6 g C m−2 ± 50.30). Our results show, the environmental and productive benefits of potato crops grown under optimal water supply.
This research sought to establish the response of the germination percentage (PG), synchrony index (E), mean germination time (MGT) and mean germination rate (MGR) of Annona squamosa L. seeds from Apulo (province of Cundinamarca) and Castilla (province of Tolima), Colombia, to treatments with 0, 50, 100, 200, 400, 600, or 800 mg L-1 of gibberellic acid (GA). All of the treatments with GA increased the PG at each point of time of seed incubation. The 600 mg L-1 GA treatment resulted in higher PGs (92.3% at 16 days for Apulo and 95% at 24 days for Castilla) and lower MGTs (8.75 and 5.38 days for Apulo and Castilla, respectively) than those found with the concentration of 0 mg L-1 GA (17.68 and 10.88 days for Apulo and Castilla, respectively). Also, treating the seeds with 600 mg L-1 GA generated higher MGRs (0.18 and 0.12 germinated seeds/day for Castilla and Apulo, respectively) than those obtained with 0 mg L-1 GA (Castilla = 0.09 and Apulo = 0.06 germinated seeds/ day). Likewise, the germination was synchronized with the application of any concentration of GA. The results evidenced a positive response to the GA application, which provided a tool for the characterization of the phenomenon of dormancy in the A. squamosa seeds.
The decoupling factor (Ω) reflects the leading mechanisms responsible for canopy transpiration and allows to know the relevance of the control of stomatal or canopy conductance on transpiration (T). The Ω is strongly dependent on water availability and can be a good approach to describe how plants minimize excessive water loss by increasing the dominance of biotic factors that controls evapotranspiration under water deficit conditions. We provided an overview of how the Ω concept can be broadly used and applied for studying the sensitivity of evapotranspiration and water conservation potential of canopies under water deficit conditions. A decoupling condition indicates that, under water deficit, the increase of canopy resistance will not have control over the transpiration. Therefore, a structural context of the canopy in which predominantly uncoupled regions will have a lower capacity to reduce evapotranspiration and avoid water losses. Furthermore, because of the water deficit, stomatal closure restricts photosynthesis more than transpiration, and water use efficiency can be lower in decoupled canopies compared to more coupled ones. Yet, we summarized the characteristics that depict structural context predisposing coupled or decoupled conditions that can indicate the capacity of canopy/crop to reduce excessive water losses and maintain a high assimilation/transpiration relation under water deficit.
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