EFFECTS OF VARIOUS DAY AND NIGHT TEMPERATURE TREATMENTS ON THE MORPHOGENESIS AND GROWTH OF SOME GREENHOUSE AND BEDDING PLANT SPECIES

Leiv M. Mortensen, R. Moe
The effects of various day and night temperature treatments on plant growth and morphogenesis were studied in growth rooms at 80 μmolm-2s-1 photon flux density for 16 h day-1. The experiment included Begonia x hiemalis, Begonia x tuberhybrida pendula, Calceolaria x herbeohybrida, Fuchsia x hybrida, Impatiens walleriana, Kalanchoe blossfeldiana, Pelargonium x hortorum (from cuttings and seed), Petunia x hybrida. (3 cvs.), Rosa sp. (2 cut and 2 pot cvs.), Salvia splendens, Senecio cruentus, Sinningia speciosa, Tagetes patula nana and Verbena elegans var. asperata. The following day/night treatments were given: 19/19, 21/15 (positive DIF) and 17/23°C (negative DIF). In addition 1.5 and 3.0 h drops to 12°C starting 45 minutes and 1.5 h before day, and an increase to about 30°C for the last four hours of the day (EOD) or the night (EON). The mean 24-h temperature was adjusted to be the same in all treatments. Plant height was not affected by temperature treatments in Senecio, Pelargonium (from cuttings), Rosa (two cut flower and two pot rose cultivars), Tagetes and Verbena. Positive DIF caused an increase in plant height in Kalanchoe only, whilst a negative DIF decreased the plant heights of Begonia, Calceolaria, Impatiens, Pelargonium (from seeds), Petunia and Salvia compared to the constant temperature. A short drop to 12°C had no effect on plant height whilst a longer drop (3 h) caused increased stem elongation in Kalanchoe and Petunia.

A high temperature at EON reduced the plant height in two species whilst a high temperature at EOD decreased the height in three species and increased it in another three.

The dry weight was generally not affected by negative or positive DIF in those species which responded to these treatments in respect of plant height. Time to flowering was more or less affected by the temperature treatments, in the different species.

Mortensen, Leiv M. and Moe, R. (1992). EFFECTS OF VARIOUS DAY AND NIGHT TEMPERATURE TREATMENTS ON THE MORPHOGENESIS AND GROWTH OF SOME GREENHOUSE AND BEDDING PLANT SPECIES. Acta Hortic. 327, 77-86
DOI: 10.17660/ActaHortic.1992.327.9
https://doi.org/10.17660/ActaHortic.1992.327.9
bedding plants, day and night temperature, flowering, greenhouse species, thermomorphogenesis