H. Krug, H.-P. Liebig
The reaction of radish (Raphanus sativus var. sativus, cv. Hilmar) to radiation and temperature during the main growth period (emergence to harvest size) was tested in greenhouses, using successive plantings and different constant day and night set points for heating.

Growth curves, the growth function (Feldmann, fig. 1), the response surface calculated with the multiplicative regression function (fig. 2) and the planning model for timing the growth periods as well as energy demands are presented in figure 3. Model results are in good agreement with data derived from holdings, if the effects of the cultivars are considered (fig. 4).

By multiplying the number of plants harvested (fig. 5) with the prices, the financial output is calculated (fig. 6). The output minus energy cost is a useful criterion of profitability.

As already shown for radish, in the Hannover climate the energy demand of the cold tolerant species tested increases with increasing set points (fig. 7).

Krug, H. and Liebig, H.-P. (1989). PRODUCTION PLANNING - MAIN GROWTH PERIOD (RADISH). Acta Hortic. 248, 181-186
DOI: 10.17660/ActaHortic.1989.248.20

Acta Horticulturae