MODEL OF CULTIVATION PLANNING IN ORNAMENT AL PRODUCTION EXEMPLIFIED WITH PELARGONIUM-ZONALE-HYBRIDS FROM CUTTINGS

An ornamental plant production model has been exemplified with cutting propagated Pelargonium-Zonale-Hybrids. The basic data were collected from several years experiments in daylight growth chambers. The main p urpose was to work out an empiric planning model at high abstraction l evel. It takes into consideration the most important parameters of pot plant production: period of cultivation, crop growth, and crop qualit y. Based on the concept of LIEBIG and KRUG (1979), the development of the model was adapted to the specific problems of ornamental plant pro duction. Important preliminary questions on the influence of temperatu re and radiation were elucidated with adequate statistical procedures. These reactions share the same tendencies for separate years, but the ir quantitative effects show essential differences. Thus a joint calcu lation of the different data to obtain an exactly predicting planning model was not possible. Therefore the model was worked out on the basi s of the most extensive experiment. The effect of the 24 hours mean te mperature (MT) on the period of cultivation has been exactly and physi ologically adequately described by a hyperbel function. The effect of diurnal thermoperiodism ((DELTA)T) in depending of the MT-level has be en taken into account with an additional-multiplicative extension of t he hyperbel function. The fresh and dry weight at anthesis could be qu antified in the same way. The fields of different ''quality assurance' ' were determined and considered in the model. Additionally a graphica l integration of the submodels was realized by relating the dependent values with similar factors (MT, (DELTA)T). Thus the integration offer s an extensive decision support to the cultivator to obtain long-term favorable temperature set points. Applicabilities and limits of the pr esented model have been discussed in comparison to other recently deve loped models.