FLOWER AND BUD ABSCISSION OF STREPTOCARPUS AND THE USE OF ETHYLENE SENSITIVENESS INHIBITORS

In different experiments Streptocarpus plants possessing about 1, 5–10 or 15–20 flowers were exposed to air containing 0, 0.1, 0.4, 0.7 or 1.0 ppm ethylene during 22 hours.
Next they were held in the dark during 0, 2 or 6 days.
Plants stressed by exposure to ethylene (C2H4) plus dark were not marketable during one to two weeks.
The youngest plants were most sensitive.
By exposing the plants to higher concentrations of ethylene the abscission of flowers and buds increased.

In order to prevent flower and bud abscission plants were pretreated with ethylene sensitiveness inhibitors, 3 days before exposing them either to air containing 0.4 ppm ethylene plus darkness, or to darkness.
Foliar sprays of 0.3 mM and 0.6 mM silverthiosulfate (STS) suppressed almost completely the dropping of flowers and buds.
Necrotic lesions appeared on the leaves after spraying with 0.6 mM STS and sometimes with 0.3 mM STS. Gibberellic acid (GA3), used as a foliar spray in a concentration of 25 ppm, 50 ppm, 100 ppm and 200 ppm diminished abscission to some degree.
However the appearance of the plants changed a lot, leaves stood upright and leaves and peduncles increased in size.
An alternative, in development for cutflowers was also used.
With the double and triple concentration of the quantity prescribed for cutflowers the plants started to die.

III International Symposium on Postharvest Physiology of Ornamentals

M.J.H. Rewinkel-Jansen

https://doi.org/10.17660/ActaHortic.1986.181.57