THE EFFECTS OF DAY AND NIGHT TEMPERATURE ON FLOWER INITIATION AND DEVELOPMENT IN CHRYSANTHEMUM

Daylit, controlled-environment cabinets were used to examine the separate effects of day and night temperature on flower initiation and the early stages of flower development in ‘Elegance’, ‘Yellow Horim’, ‘Hurricane’, ‘Blue Marble’, ‘Robeam’, and ‘Snowdon’. The performance of plants grown at constant temperatures of 10, 15 and 20°C was compared with that of plants grown in either a 20°C day : 10°C night temperature combination or a 10°C day : 20°C night temperature.
As the day and night periods were each 12 h long the average temperature in the two combination treatments was 15°C.

The progress of flower formation was correlated with average temperature in four cultivars but was delayed by low day temperature in ‘Hurricane’ and ‘Elegance’ and promoted by the combination of 20°C day : 10°C night temperature in ‘Elegance’. The rate of leaf emergence was correlated with average temperature in all six cultivars.
Internode extension was not correlated with average temperature but was influenced mainly by the day temperature.
The longest internodes were produced at the highest day temperature (20°C) in all cultivars, a response which was accentuated in ‘Hurricane’, ‘Robeam’, and ‘Snowdon’ if the following night temperature was 10°C. The significance of these results is discussed in relation to fuel-saving regimes for the production of cut-flower chrysanthemums.

Symposium on Chrysanthemum

K.E. Cockshull, D.W. Hand, F.A. Langton

https://doi.org/10.17660/ActaHortic.1982.125.12