DYNAMIC ONTOGENY MODEL FOR WINTER-WHEAT CONSIDERING WATER AND NITROGEN STATUS

A dynamic winter wheat ontogenesis model for the period from the end of tillering to harvest is presented. The controllable factors influencing ontogenesis, which are reproduced in the model via normalized stress factors, include not only temperature but also water and nitrogen. The model was fitted to cv. Alcedo grown at Muncheberg, a diluvial site, on the basis of observations of different water and nitrogen variants during 1980-1985 (total of 14 time series). The mean deviation between model and observed data was below 3.6 days, for the most important growth stages (DC31, DC51, DC61) even 3.0 or ess days. A possible use of the model for computer-aided crop management is pointed out.