THE EFFECT OF WATER STRESS ON ETHYLENE PRODUCTION AND ETHYLENE SENSITIVITY OF FREESIA INFLORESCENCES

Author:	G. Spikman
Abstract: The Freesia is an important cut flower in the Netherlands. However, its keeping quality is moderate. From detached inflorescences held in water up to 40% of the buds does not grow out to give flowers. Malformation of buds and flowers also occurs. It is not yet understood which role ethylene plays in the inflorescence development of Freesia. A maximum production of about 8 nl.inflorescence^-1.h^-1 is measured. There is no evidence that senescences of individual florets is preceded or accompanied by a higher ethylene production. Ethylene production of waterstressed inflorescences is higher than that of non-stressed inflorescences. An ethylene peak is reached at day 3 after the stress period for waterstressed inflorescences, at day 4 for the non-stressed inflorescences. After the ethylene peak the production rapidly declines to a low level. Until then no difference in the rate of senescence of individual flowers of an inflorescence is observed when stressed and non-stressed flowers are compared. However, more malformation and dying of buds occurs in the waterstressed inflorescences. Freesia inflorescences are very sensitive to ethylene. Exposure to ethylene concentrations (ranging from 0.05 to 1.0 μ1.1^-1) causes considerable damage to buds (die or get malformed).
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