U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


Document Type


Date of this Version

May 1993


Published in Agron. J. 85:758-763 (1993).


The Haun, Feekes, and Zadoks-ChanpKonzak developmental stage scales are often used to report phenological information for wheat (Triticum aestivum L.) development. Agronomists familiar with one of these scales may have only a passing acquaintance with developmental scales other than the one they consider most appropriate for their purposes. This makes review and interpretation of the literature more difficult. Although wheat development models often report phenological results, they generally use no more than one scale. For these reasons, and because there is not a simple numeric correspondence among the three scales, a computer program to convert among them is a useful tool. SCALES is a three-module FORTRAN program that relates the three scales based on published descriptions. The interactive user interface module requests an input scale value and minimal additional information, which the conversion module uses to determine values for the remaining two scales via a dichotomous key. The output module writes the conversion results to the monitor. SCALES may be used independently for comparing phenological data based on different developmental scales, or the conversion module may be incorporated into computer models to provide output of developmental stage information for the simulation.