ISHS Acta Horticulturae 109: III International Symposium on Flower Bulbs
DAYLENGTH AND THE FLOWERING PERFORMANCE OF TULIPS |
| Authors: | Gordon R. Hanks, A.R. Rees |
| Abstract:
Bulbs of tulip cvs. 'Apeldoorn', 'Golden Apeldoorn', 'Paul Richter', 'Rose Copland' and 'Trance' were cooled outside on a standing-ground until 'ready to house'. They were then transferred to growth cabinets to examine the effects of daylength on stem extension and flowering at a growing temperature of 9°C. Four daylengths were tested (a) 8 h short day (SD); (b) 8 h SD with one hour tungsten light-break (LB); (c) 12 hour long day (LD) consisting of 8 h high-intensity light followed by 4 h low-intensity tungsten supplement, and (d) 16 h LD (8 h high plus 8 h low). In all 5 cultivars, stem length at anthesis was shortest in SD, and increased progressively under daylengths of 12 and 16 h. With 'Paul Richter', 'Rose Copland' and 'Trance' the effects of LB were about midway between those of SD and 12 h LD; with the 2 Darwin Hybrid cultivars, LB was less effective. Flowering date, flower size and flower quality were not significantly affected by daylength. Ways of incorporating this LD response into commercial forcing are discussed. | |
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