TEMPERATURE CONTROL TO AVOID BOLTING OF KOHLRABI USING A MODEL OF VERNALIZATION

H.-J. Wiebe, H.-P. Liebig
The development of flower stalks (bolting) reduces the market quality of kohlrabi. Bolting occurs as a result of low temperature (vernalization). At optimal temperatures for vernalization between 2 and 8°C the critical exposure time is 6 weeks. To avoid bolting the temperature after planting has to be higher than 12°C. But the temperature can be lower if strong devernalization effects are used. Daily or weekly interruptions of low temperature by some hours of higher temperature (>14°C) have a lower effect on bolting than the corresponding mean temperature.

For saving energy a model of the vernalization process as a basis for temperature control has been developed. The parameters used are the effects of the temperature of each hour on vernalization or devernalization. The program starts with 0% at planting date, then it adds the response values of each hour. For example: one hour 5°C has a vernalization effect of + 0.1% and one hour 18°C has a devernalization effect of - 0.6%. If the sum of + 20% is reached, the set point for the next day has to be higher than 14–16°C. Preliminary results are in general according with the model. For further refinement more experiments are needed. If periods of lower energy demand (e.g. wind related regimes) for heating are preferred additional energy saving is possible.

Wiebe, H.-J. and Liebig, H.-P. (1989). TEMPERATURE CONTROL TO AVOID BOLTING OF KOHLRABI USING A MODEL OF VERNALIZATION. Acta Hortic. 248, 349-354
DOI: 10.17660/ActaHortic.1989.248.43
https://doi.org/10.17660/ActaHortic.1989.248.43

Acta Horticulturae