Evaluation of four degree-day estimation methods  in eight Colombian coffee-growing areas

Carlos Andrés   Unigarro; Leidy Natalia   Bermúdez; Rubén Darío   Medina; Álvaro   Jaramillo; Claudia Patricia   Flórez

Evaluation of four degree-day estimation methods in eight Colombian coffee-growing areas

Autores

Carlos Andrés Unigarro

Leidy Natalia Bermúdez

Rubén Darío Medina

Álvaro Jaramillo

Claudia Patricia Flórez

Editor

Universidad Nacional de Colombia

Descripción

ethods to estimate the accumulation of degree-days based on maximum and minimum temperaturesare are commonly used to determine relationships or to adjust phenological models based on the “physiological time”. Degree-days are obtained indirectly by these methods, this information is not generally available on hourly or shorter time scales due to the type of equipment used to record data or a data loss in histori - cal time series. To compare the performance of such methods, degree-days were estimated with four indirect methods in eight Colombian locations during 1 year. Each indirect method was evaluated in comparison to the numerical integration method by the trapezoidal rule (reference method) using temperatures recorded every 5 min. Based on the percent bias error, the methods proposed by Arnold, Ometto and Snyder tend to overestimate thermal time, whereas the Villa-Nova method underestimates this time, but with a lower performance as regards to the previous ones.