THERMOMORPHOGENESIS IN POT PLANTS

Plant morphogenesis was influenced more by the difference (DIF) between day temperature (DT) and night temperature (NT) than absolute temperature in a wide range of pot plants, including Campanula isophylla, Euphorbia pulcherrima and Begonia x hiemalis. Plant height and plant diameter increased as DIF increased.
In Campanula DIF interacted with light quality in the following manner:

1. Day-extension with light from incandescent lamps (low R/FR ratio) eliminated the negative DIF response,

2. Day-extension with light from fluorescent lamps (high R/FR ratio) enhanced the negative DIF response.

Stem elongation in plants is sensitive to temperature fluctuations during the daily 24-hour cycle. Euphorbia and Begonia internode lengths (plant heights) were significantly reduced when plants received a cool temperature pulse during the first 2 hours of the day.
In Begonia the strongest response to cool temperature pulse was obtained during the last 2 hours of the night.
A possible involvement of an endogenous rhythm in temperature sensitivity during the photoperiod is suggested.

First European Workshop on Thermogenesis and Photomorphogenesis in the Cultivation of Ornamentals

R. Moe, L.M. Mortensen

Thermomorphogenesis, pot plants, endogenous rhythm, DIF, flowering

https://doi.org/10.17660/ActaHortic.1992.305.2