PHENOLOGICAL PREDICTION OF POTATO CROP BY MEANS OF THERMAL TIME

Abstract

The objective of this research was to evaluate three methods to predict potato crop (Solanum tuberosum L.) phenology by means of thermal time, which were applied on 15 commercial plots sowed with the variety ‘Alpha’ in northern Sinaloa, México. The compared methods were: average temperature, degree days (°D) and potato days (P-days), all of them calculated with data obtained by field monitoring of each phenological stage during two crop seasons, Autumn-Winter seasons 2005-2006 and 2006-2007. Results showed that the best method to predict the phenology of this potato variety by means of thermal time was the P-days technique because it produced the lowest values of variation coefficient with 0.07 and of standard deviation with 18.03, for all the analyzed phenology stages. To compare the errors in thermal requirements obtained with each method in the plots, other plots were used for validation, and so it was confirmed that the P-days method showed the smallest errors, with 3.6 and 3.2 % for the root mean square error RMSE and the mean absolute error MAE, respectively.