H.-P. Liebig
Each production system of crop growth can be described by a model computing the effects of a defined input on the desired ouput. Depending on the purpose of the predicting system parts of the real system are modelled with different abstraction levels.

Therfore, a certain way of construction is preferred wether it serves more as a management tool, or for explanation of the biological process itself. For the management the models may be divided into planning models (they run before and have no feedback to real production) and control models (they run after crop growth was started and feedback may be established).

The Hannover approach is one way of developing a planning model with its possibilities and constraints. Data from several experiments conducted under conditions comparable to praxis were collected. From fitted growth functions mean growth rates were derived; mean data of temperature, radiation and CO2 were computed for the same period. Response surface could be estimated by using multiple regression technique or even better by a multiplicative model. The different approaches are discussed.

Results of the planning model are the estimation of the relative effect of growth factors which can be used for optimization of production and the crop growth duration with its energy demand. Preliminary comparisons between different models indicate the necessity of planning models to be as simple as possible.

Liebig, H.-P. (1989). MODELS TO PREDICT CROP GROWTH. Acta Hortic. 248, 55-68
DOI: 10.17660/ActaHortic.1989.248.4

Acta Horticulturae