A.A. De Hertogh

Increases in ethylene and carbon dioxide production by Tulipa gesneriana L. ‘Prominence’ after completion of the cold-requirement

Abstract Bulbs of Tulipa gesneriana L. ‘Prominence’ were either specially pre-cooled at 5 ± 0.5°C or held at 17 ± 0.5°C in a flow-through system equipped for atmospheric sampling. Bulbs at 17°C had low CO2 and C2H4 production rates until January when they began to increase. An initial peak of C2H4 production occurred during the 2nd week of pre-cooling, followed by a major increase after 12 weeks. In addition, bulbs were specially pre-cooled for periods of 2–16 weeks (2-week increments). The bulbs were then transferred to 17 ± 0.5°C, where initial periods of special pre-cooling of greater than 12 weeks resulted in a dramatic increase in respiration rate over bulbs cooled for less than 12 weeks. These increases in C2H4 and CO2 liberation appeared to be related to completion of the bulb cold-requirement. However, no surge of shoot elongation occurred after 12 weeks of pre-cooling and transfer to 17°C.

The effects of scale wounding of tulip bulbs on ethylene evolution, plant growth and flowering

Abstract Scale wounding significantly accelerated flowering of Tulipa gesneriana L. bulbs that had been stored for 3,6 and 9 weeks at 2°C for ‘Apeldoorn’ and for 3 and 6 weeks for ‘Oxford’. In addition, final scape length was significantly longer in plants produced from wounded bulbs after 3 and 9 weeks of precooling for ‘Apeldoorn’ and after 3 weeks for ‘Oxford’. Wounding increased ethylene production in all treatments of both cultivars. ‘Oxford’ produced significantly more ethylene than ‘Apeldoorn’, however, the increased ethylene production did not produce floral abortions.