RESUMEN
Coffee is a crop of global relevance. Indirect somatic embryogenesis has allowed plants of different coffee genotypes to be massively regenerated. The culture medium composition can affect the calli characteristics that are generated and their ability to form somatic embryos. This research aimed to determine the influence of the type of callus, growth regulators, and phytagel concentration on the embryogenic capacity of the Colombia variety. Leaf explants were cultured on Murashige and Skoog medium with 2,4-dichlorophenoxyacetic acid (2,4-D) (0.5-1.0 mg L-1), benzylaminopurine (BAP, 1.0 mg L-1), and phytagel (2.3-5.0 g L-1). The explants generated two types of calli: friable (beige, soft, watery, easy disintegration, polyhedral parenchyma cells) and compact (white, hard, low water content, difficult disintegration, elongated parenchyma cells). About 68% of the total callus generated was compact; this type of callus produced a greater number of embryos (71.3) than the friable one (29.2). The number of differentiated embryos was significantly affected by the concentration of phytagel; higher concentrations (5.0 g L-1) resulted in larger quantities (73.7). The highest number of embryos (127.47) was obtained by combining 1.0 mg L-1 2,4-D, 1.0 mg L-1 BAP, 5.0 g L-1 phytagel, and compact callus.
RESUMEN
Coffea arabica is one of the two most consumed coffee species in the world. Micropropagation through somatic embryogenesis has allowed the large-scale propagation of different coffee varieties. However, the regeneration of plants using this technique depends on the genotype. This study aimed to develop a protocol for the regeneration of C. arabica L. var. Colombia by somatic embryogenesis for its mass propagation. Foliar explants were cultured on Murashige and Skoog (MS) supplemented with different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BAP), and phytagel for inducing somatic embryogenesis. In total, 90% of the explants formed embryogenic calli with a culture medium containing 2 mg L-1 of 2,4-D, 0.2 mg L-1 BAP, and 2.3 g L-1 phytagel. The highest number of embryos per gram of callus (118.74) was obtained in a culture medium containing 0.5 mg L-1 2,4-D, 1.1 mg L-1 BAP, and 5.0 g L-1 phytagel. In total, 51% of the globular embryos reached the cotyledonary stage when they were cultured on the growth medium. This medium contained 0.25 mg L-1 BAP, 0.25 mg L-1 indoleacetic acid (IAA), and 5.0 g L-1 of phytagel. The mixture of vermiculite:perlite (3:1) allowed 21% of embryos to become plants.
RESUMEN
Objective. This paper presents extensions to the statistical validation method based on the procedure of Freese when a model shows constant bias (CB) in its predictions and illustrate the method with data from a new mechanistic model that predict weight gain in cattle. Materials and methods. The extensions were the hypothesis tests and maximum anticipated error for the alternative approach, and the confidence interval for a quantile of the distribution of errors. Results. The model evaluated showed CB, once the CB is removed and with a confidence level of 95%, the magnitude of the error does not exceed 0.575 kg. Therefore, the validated model can be used to predict the daily weight gain of cattle, although it will require an adjustment in its structure based on the presence of CB to increase the accuracy of its forecasts. Conclusions. The confidence interval for the 1-α quantile of the distribution of errors after correcting the constant bias, allows determining the top limit for the magnitude of the error of prediction and use it to evaluate the evolution of the model in the forecasting of the system. The confidence interval approach to validate a model is more informative than the hypothesis tests for the same purpose.
Objetivo. Presentar extensiones al método estadístico para validar modelos basado en el procedimiento de Freese cuando el modelo presenta sesgo constante (SC) en sus predicciones e ilustrar el método con datos provenientes de un modelo mecanístico inédito para la predicción de ganancia de peso de bovinos. Materiales y métodos. Las extensiones fueron la prueba de hipótesis y error máximo anticipado para el planteamiento alternativo y el intervalo de confianza para un cuantil de la distribución de los errores. Resultados. El modelo evaluado presentó SC, una vez eliminado y con un nivel de confianza del 95%, la magnitud del error no sobrepasa 0.575 kg. Por lo que el modelo validado puede usarse para predecir la ganancia de peso diaria de bovinos, aunque requerirá un ajuste en su estructura con base a la presencia de SC para incrementar la exactitud en sus pronósticos. Conclusiones. El intervalo de confianza para el cuantil 1-α de la distribución de los errores una vez que se corrige el sesgo constante, permite determinar una cota superior para la magnitud del error de predicción y usarla para evaluar la evolución del modelo en predicción del sistema. El enfoque de intervalos de confianza para validar un modelo es más informativo que las pruebas de hipótesis para el mismo propósito.
