ISHS Acta Horticulturae 673: IX International Symposium on Flower Bulbs
CONTROLLING PLANT HEIGHT AND UPPER LEAF NECROSIS IN ORIENTAL LILIES BY 'NEGATIVE DIF' |
| Authors: | H. Kok, H. van Aanholt, H. Gude |
| Keywords: | Oriental Lily, DIF, plant height, upper leaf necrosis |
| Abstract:
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. | |
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