CONTROLLING PLANT HEIGHT AND UPPER LEAF NECROSIS IN ORIENTAL LILIES BY ‘NEGATIVE DIF’

Due to the low light levels during winter in greenhouses in The Netherlands, lily stems grow too tall and show a lack of firmness. ‘Negative DIF’, the negative difference between day and night temperatures (night temperature higher than day temperature), proved to be a simple and effective tool to reduce plant height and to enhance the firmness of the stems.
Five Oriental lily cultivars, ‘Star Gazer’, ‘Acapulco’, ‘Alliance’, ‘Casablanca’ and ‘Siberia’, were forced in a greenhouse with a day temperature of 14°C and a night temperature of 20°C (negative DIF 6°C). Because forcers use 16 h of supplementary lighting per day, the day/night period was 16/8 h.
The effects of negative DIF were compared with the effects of a constant greenhouse temperature with the same temperature sum.
The Longiflorum ‘Snow Queen’ was used as a reference cultivar, well known for its strong response to negative DIF. The negative DIF regime yielded a shorter crop with firmer stems than a constant temperature.
Other effects of negative DIF were a shorter forcing period and a reduction in upper leaf necrosis.

IX International Symposium on Flower Bulbs

H. Kok, H. van Aanholt, H. Gude

Oriental Lily, DIF, plant height, upper leaf necrosis

https://doi.org/10.17660/ActaHortic.2005.673.38