Comparison of eight degree-days estimation methods in four agroecological regions in Colombia

Abstract

Eight methods were used to estimate degree-days in four Colombian localities. Four methods have been previously proposed in literature: Simple Sine, Double Sine, Simple Triangle, and Double Triangle methods. The other four methods are proposed in this research: Simple Logistic, Double Logistic, Simple Normal, and Double Normal. The estimation of the degree-days through hourly temperature values was used as the reference standard method, and the four localities from where the temperature values were taken were the municipalities of Cajicá (Cundinamarca), Santa Elena (Antioquia), Carepa (Urabá Antioqueño), and Ciudad Bolivar (Zona cafetera Antioqueña). Degree-days obtained by all methods under study were compared through linear regression to those obtained by the reference standard method. There were differences in the correlation of each method to the reference when compared within each region and among regions. The Simple Logistic and Double Logistic methods showed the best performance with acceptable R 2 values and considerably lower bias than the other methods. The poorest fit was found in Cajicá, where the average R 2 was 0.571. For the regions of Santa Elena and Carepa, the average R 2 was 0.756 and 0.733. The best fit was found in Ciudad Bolivar, with an average R 2 of 0.826.Key words: degree-days, thermal time, temperature threshold, statistical modeling. Comparação de oito métodos para calcular graus-dia em quatro regiões agroecológicas ResumoEstimativas de graus-dia foram obtidas pelos métodos de seno simples e duplo, triangulo simples e duplo, as quais são amplamente utilizadas. Quatro novos métodos foram propostos e avaliados nesta pesquisa: logística simples e dupla, normal simples e dupla, baseadas em regressão logística e distribuição normal. Registros horários de temperatura obtidos em Cajicá (Cundinamarca), Santa Elena (Antioquia), Carepa (Urabá Antioqueño) e Ciudad Bolivar (Região tradicional da cultura do café) foram utilizados para obter estimativas da soma térmica com maior precisão sendo, portanto, considerada como a referên-cia para comparação utilizando regressão linear. Foram constatadas diferenças entre o ajuste dos métodos dentro de cada região e entre regiões. Foram observados os maiores coeficientes de determinação (R 2 ), nos métodos de logística simples e logística dupla. O menor coeficiente de determinação, de 0,571, foi obtido em Cajicá enquanto nas regiões de Medellín e Carepa, o R 2 foi de 0,756 e 0,733 respectivamente. O melhor ajuste foi obtido em Ciudad Bolivar, com um R 2 igual a 0,826.Palavras-chave: graus-dia, tempo térmico, temperatura basal, modelagem estatística.

Effect of nitrogen, phosphorus and potassium fertilization on the yield of broccoli cultivars

“…The cumulative day degrees (dg) or thermal time, which are employed in agriculture to quantify and predict phenological events accurately during the chronological time based on the time of the year (McMaster and Wilhelm, 1997;Roltsch et al, 1999;Ramírez et al, 2015), were estimated using the free program Degree Day Utility (DDU) version 2.3 (Univ. of California, 1994).…”

Functional growth analysis of diploid potato cultivars (Solanum phureja Juz. et Buk.)

“…The developmental time was measured in terms of thermal time in accumulated degree-days (ADD). The methods followed to compute the thermal time were proposed by Rodríguez et al (2012) with a threshold temperature of 2 and 29°C (Struik, 2007) the focus is on the temperature range between the base temperature and the ceiling temperature as experienced by a plant in the field or in facilities of climatic control. Temperatures at which the plant can no longer function or is even directly damaged (for example, temperature at which the plant is killed by frost or scorched by heat.…”

Modelo de simulación del crecimiento y desarrollo de la papa criolla

“…El tiempo termal expresado en grados día (GD) o unidades calóricas acumuladas durante un día (i) se calculó utilizando el modelo logístico simple propuesto por [30] y, el total de grados día acumulados (GDA), en cada tiempo (t) del ciclo se expresa como Los umbrales de temperatura mínimo (T min ) y máximo (T max ) representan las temperaturas máxima y mínima entre las cuales la planta de papa acumula unidades calóricas y se produce el crecimiento, no obstante, si la temperatura del día excede el umbral superior o es inferior al mínimo, los procesos de crecimiento se detienen (ver Tabla 2).…”